So I'm currently trying to figure out the best/cheapest way to build my 87' GTA to have 350-400rwhp. I eventually intend on putting in a procharger w/Intercooler. However, I want to do this after I achieve 350 hp with heads, cam, ect. My knowledge of modding out engines is limited so I decided to ask the good ol' boys here and see what they would do specifically. Links to parts are appriciated since most older post's links are broken. Last thing is I really want to keep that TPI look with them runners and plenum, but it doesnt have to be exactly TPI. I want to get to >350 with the least amount of modification possible (excluding nitro,turbo,SC). Any Ideas for dream builds?

 

Id shoot for similar TQ numbers not hp with the tpi. Supercharge from there

 

What is the rational? I'm not sure I follow what you mean

 

Vortec truck engine with a cam and a FIRST manifold. Probably the simplest way to get you into that neighborhood while keeping the TPI look.

GD

 

-Tq and hp always cross at 5252rpm
-Most stock bottom end, mostly OEM V8 engines like to stay 6000rpm or less for longevity and flow rate reasons
-Torque generally follows VE, Volumetric efficiency is the result of cam/valve behavior, therefore torque per RPM is purely a user-choice component.

couple conclusions:
1. every engine that exists, they all make more torque than power before 5252 rpm
2. with 6000rpm limit, the difference in power from torque will always be the same (about 15%) max

examples
350torque at 5252rpm = 350hp
350torque at 6000rpm = 400hp
difference of approx 15%

200torque at 5252rpm = 200hp
200torque at 6000rpm = 228hp
difference of approx 15%

Doesn't matter how much torque the engine produces, the result is purely percentage based when it comes to power

 

Well I don't want to swap the engine. It only has 12k miles on it. I assume you mean Vortec heads, so which would you recommend to go with the FIRST manifold. I have been looking in that direction. But I just want to know all the pieces I will need to make it all work. And what cam or what am I looking for in a cam to make these kind of numbers.

 

Vortec heads are relatively cheap and if you get them with an engine..... well ya already have em. It can easily cost $500+ to turn them into 350 wheel heads though. If you are keeping your stock bottom end then get a set of AFR 195's and have the FIRST manifold made for those (they are made to order).

You'll need to pick an EFI friendly cam and choose a tuning solution. Can't run 350 wheel on a stock tune. Definitely want to carefully consider what you skill level can support also.

What's the budget?

GD

 

Tpi will need a welded up aftermarket base and likely custom runners, but maybe could do it with heavily worked slp’s ifyou can find them but doesnt look like tpi. Big tube runners may work with the base opened up enough. The california guys have done this. Look at afr or equal 195-210 heads. Custom hyd roller 230 ish degs. Be nice to have a good shortblock 10.5:1 or so comp. next best option would be try a FIRST tpi

wouldnt be to concerned at all with na hp if you plan to supercharge

regular tpi bolt on parts plus similar cam and head will do 500-550 whp 8-12 psi with a strong shortblock depending your trans and rear end combo. Did a 383 with a 224 cam and did 550 thru a manual trans on 8 psi

 

So my budget for this is the least amount of money to achieve the goal. I'm trying to keep it in the 5k range by doing a good bit myself (short of machineing). I feel rather comfortable doing the work and not jacking it up because I am not in a rush, so I have time to figure things out. I definatly appriciate the specific info on #s though cause I get lost in all that jive, but I'm learning it. So far I have AFR 195s ($1750), Custom Cam ($350), FIRST TPI (??), Tuner (??). I need to do some more reasearch on the tuners, I'm not sure 1k+ from FIRST is reasonable. At this point what other odds and ends should I be worried about? Need a stronger fuel pump for the larger injectors and increased air induction? Any drivetrain mods needed at this level, or after SC?

 

If you want a tpi you get the best bang for buck with FIRST. It may sound expensive but price out a base runners and throttle body separately for normal tpi which not many make anymore so you are stuck trying to find old stock that ppl want big money for.

The first will likely be the easiest out the box solution to get you close to your goals.

Do you have a 350 stock shortblock? Getting that to make the power may be tougher depending on its condition. Plus if you want a blower i wouldnt spend time doing all the na bolt ons and stuff on stock cast internals. Just leave it mild and let the boost do the work. Ideally you rebuild the bottom end with forged stuff, but you have to make the decision what you want for ultimate goals. 10.5-11:1 comp for na power or go 9-9.5:1 or so for pump gas boost friendly power.

Your boosted goals if you have a 350 whp base plant, should be in the 550-700 whp range depending what blower. That will need 2 255 fuel pumps or one 400-450 lph pump. Might as wel upgrade now.

tuners? Nobody does these cars anymore. You’ll have to learn or maybe work with someone local or online which would be a long drawn out process doing burns over mail and emailing logs. When boost comes into play you WILL be on your own if you elect to do it with a map sensor on stock ecm using code $59 or boosted $8D. Its more for an advanced tuner imo

so may have to budget aftermarket ecm like holley hp. 2-3 grand there wth every thing

 

you are better off selling the 12,000 miles engine rather than opening it yourself and doing mechanic work to it without the necessary experience.
If you've never done these sorts of things or have no experience with atoms (literally a master's degree in a science field) then it will almost certainly end poorly or never be finished, historically this is the general outcome.

Or just leave it alone and drive it to 150k+ then swap it or something


--- bigger picture
The cost of an 02-06 LS truck engine from a junkyard which will support 700-800rwhp is $300.
And there is a large selection to choose from. They last 300k 400k 500k miles in trucks, high mileage potential is a hallmark of modern engine.
LS engines don't need head/intake upgrades, they don't need bottom end upgrades, they don't need extra parts to make a basic 500-800rwhp.
Just cam/spring, boost.

In comparison, many will spend $5000 just in parts for an older engine to get anywhere close, and still have the insufficient bottom end character (another 5 to 10k in upgrades), and still:
lack of oil pan girdle support,
no sequential EFI,
no coil per cylinder,
outdated difficult to deal with electronics,
outdated oiling and pcv system,
leaking seal character,
all of the modern amenities of a $300 LS truck engine are considered a 'standard' of high performance minimum will be missing from your 5 to $10,000 'built' version of an older engine.




I don't know you and I write with very little information to go on, but
-you said 5k is the budget and when it comes to cars and 500hp+ 5k is never the budget.
-you said 12k miles on an old (20 years old? ) engine which is very strange and possibly (numbers matching) worth more unmodified to somebody?
-from 02+ the Chevrolet engines got way better than anything prior, and they are very affordable. It costs more up front to use one but in the long run you will go farther, make more power, and save money if you kept the car and continue to actually drive it (and not just build it and let it sit like many do)

Finally if you are new to engines in general and modding, you want a cheap, disposable engine to work with first and learn one. That would be your run of the mill $300 LS

 

Keep in mind an ls swap involves alot more than just a 300$ engine which idk if you can find them that cheap anymore. Atleast around here they bring several hundred more cuz ppl know what they are now and why people want them lol the secrets been out. 500-700 may be more realistic, upwards of 1000+ for a good 6.0. But the 4.8-5.3 are better for turbo boost anyway. But you said blower so may want abit more cubes so you dont have to drive the blower as hard to make power

 

It can easily become 15k to 20k swap said and done. The engines are considered 'free' at that point, +/- ~$500 is negligible in the scope of the overall project.

On average the truck 4.8/5.3/6.0 handles what many modern engines handle, 200hp/liter if tuned properly with the right fuel(E85) is no issue
The aluminum L33 5.3L version is the superior of the bunch but costs more of course. The Aluminum L33 holds the world record iirc for stock bottom end something or other. It's as good as any iron block for boost 800rwhp easily, and weighs 100lbs less than typical iron engine.

I recommend start with an IRON "free" version and once tuned and done, swap over to the aluminum more expensive version.

Keep in mind blowers (belt driven FI) absorb power directly from the crankshaft, it can be as much as 80-120hp on mild setups (500-800hp)
That means if you got 700 with a turbo, you only get 600 with the blower, but the engine will see the same stress as 700.
The blower will be adding more heat, generally they beat the crank pulley (front bearings).
It's technology which is still available but not recommended for daily drivers or reliable vehicles.
Auto manufacturing has turned to turbocharging.

 

Thanks for the replies, I'll have to read over them again after this football game and get a better Idea of what is going on. It is an all original 87 GTA 5.7L (garage find) I want to keep as much original as possible and definatly maintain that TPI look. I don't want 700-800hp. I was thinking a procharger with intercooler to get around 500-600 when all is said and done. I want to be able to drive as a fun street car. Thanks for the recomendation on trying to work on a different motor first, to make sure I dont jack up my original. This is my first time doing something like this. Right now I'm just in the planning stage and trying to figure out what I need to get. I won't be breaking into it tomorrow.

 

If its an original stock bottom end forget the blower and just do your na heads cam stuff

or forget the heads cam stuff and just do the blower. Either way i wouldnt want to put too much power on stock bottom stuff. 400 whp maybe. Sure some guys have done more than that. But it will stress things on a stock rod 2 bolt main deal imo

ofcourse mild head cam package for 270-300 whp plus the blower on 5-6 psi would tune easy and be very safe and reliable and get you 400 whp or so maybe more. 7-9 psi on a stock motor would get you to near 280-300 whp most likely. I know my 305 tpi motor really came alive on 8 psi turbo

 

imo knowing the mileage and age,

1. focus on restoration components:
restore suspension, refresh rubbers, perfect control arm geometry for a high quality, lightweight set of forged wheels if applicable, finish alignment
add support and structure while not doing anything permanent like welding (brace the chassis to keep flexing to a minimum but don't weld anything in so it can be reverted back to original condition)


2. focus on maintenance:
-wash the engine and drivetrain, including under the car, by hand using variety of solvents varying in strength (degreaser, simple green, dish soap, etc)
this will help you find and keep track of leaks which may develop
An engine that old may need it's seals replaced (front main, rear main, etc..) to keep an eye on such things
-perform all maint (replace hoses, remove or replace outdated emission systems (such as cat and egr/air)
-inspect factory air intake tracts (they are very important) for any missing parts, damage, tampering, and finally carbon buildup/filth which should be washed out
-ensure the OEM paper filter system is in place to protect the engine, and achieve proper PCV (do not use any aftermarket cold air intake systems which improve power at the cost of oil and air quality)

3. once the engine health and suspension has been restored and the vehicle is deemed worthy of additional modification here are your most user friendly options in no order
a. light weight rotating parts are good in general, a good set of forged lightweight wheels is great for heavy vehicles with low power for a number of reasons
b. weight reduction anywhere is basically free and every bit improves everything: handling, acceleration, braking
c. transmission modifications (torque converter or superior clutch quality) shift kits, basic trans upgrades for longevity and lightweight, more well balanced parts if possible (aftermarket 9.5" converter is lighter and more well balanced and efficient than oem for example)
d. matching the rear tire size with differential gearing and vehicle application as limited slip performance

I would not modify the engine much if at all. The mileage is too low, the model is too old, the reward vs cost ratio is awful.
It can be done but thousands may be spent for very little in terms of performance. IMO the money:value is better spent in maintenance and 'free' mods such as porting (done by hand yourself to learn). A cam/spring would be considered normal 'performance' mod but due to the age of the engine (irreplaceable) plus the low mech experience of owner doing mods it is unwise to take that risk.

-in terms of forced induction
The engine is so old and irreplaceable, and the tuning difficulty is such that the use of forced induction is lunacy without an inane added expense(stand-alones, forged internals, complete overhaul type of mods) which is unnecessary for the LS (it has a computer for boost and decent tuning scaffold for the OEM ecu among other amenities) making the older pre-02 Chevrolet engines obsolete when it comes to any kind of forced induction IMO

 

It would be fine. The forseen issue isn't whether or not the engine will survive at 400bhp. The issue is low mechanical experience and no tuning experience of the owner which when added to the irreplacability of such an old, low mileage engine, make it a dangerous pathway, the car could quickly go from running fine to down, and stay down, for a very long time, over a very simple issue perhaps related to the age or tightening procedure or cleanliness.
Hes better off just driving it minus the 50hp or whatever and avoid the whole risk of uncertainty "it if ain't broke don't fix it"

If it was a worn out motor with good compression and clean oil, I would def say take it apart partially to clean it up (heads) replace the valvetrain hardware (cam/spring) port work or upgrade the top and go. But it's got 19k lol

 

stock ecm out of a 91-92 is fine for forced induction. I’ve been 9.70’s on it with no issue and had run my last combo on it at 15 psi which later went 9.40’s with a different ecu. Ls1 411 is good, maybe better, but not the end all be all. The timing in boost isnt as controllable as aftermarket. Not sure on the gen iv p38 or whatever it is

i like to cap stock ring gap cast bottom sbc ends in stock form at 400’s whp. That should live awhile like that. Totally depends tho but you just dont see nany guys doing that and higher on these L98’s. Rpm will hurt them abit but so will low rpm torque that tpi gives. Tpi plus boost can be hard on rods. Big torque at 2500-3000 rpm is not good idea lol. Lsx motors live by avoiding low rpm torque. If you are good with your boost curve and timing, you can avoid the issues. Centri car helps

 

I have a gen3 411 and the timing for boost is absolutely customizable, you just have to read it carefully.
There are many timing compensation maps which for some reason escape people on the hptuners forums until I keep pointing it out.

I'm not saying the stock ecm can't work with boost. In fact I can make any computer work with boost. Because we have the experience and know-how it is easy for us.
However, for a novice starting out, with no knowledge of either/any computer,
for this: I am saying that there is no up-side to learning how to use the old 'distributor' style computers when it is basically a dead tech and they should be or will eventually be moving on to the sequential EFI w/ coil-per-cylinder application at this point (2019) if you have the money to support a proper FI installation in the first place


This is a myth. While its true that lower rpm generally lowers acceptable window for timing, it would do so for all engines in the world (not just LS engines).
If the fuel quality and temperature is appropriate then there is no reason why torque at any RPM would be any different at any other RPM.
The critical stresses on rods at higher rpm are greater

A roots blower applies a full boost conditional immediately with wide open throttle. For a manual transmission car, this could be done at quite a low RPM, since the 60's. And the rods seem to do fine, if the engine is tuned properly since that 50 years ago time frame.

 

I guess you forget even GM put the LS computer on 350s. The trucks in Mexico and South America even had the Blue/Green connector LS PCM with a 5.7 Vortec. I used the engine tune from one doing a tune for a guy swapping a 383 into an 05 Astro van.
​​
350 parts are stupid easy to find and cheaper than LS.

I am actually finishing swapping the cam in my 11:1 383 this weekend. Should be around 550 hp at the crankshaft with the new cam.

With 1.7 rockers it specs out.

284/309 @ 0.006
232/244 @ 0.050
.627/.627 lift
108 LSA

It was degreed in on a 103 ICL. Calls for 104 ICL but I left it at the 1 degree advance it dropped in at. A little more low-end torque never hurt anyone pulling around 6,200 lbs with a small block.

Now I am only waiting on the 1200 cfm 4bbl throttle body to put on my intake manifold.
​​​​​

 

explain to me how to get around the cylinder air mass calcs in the timing table for a boosted 0411 car? You hit the max gram sec value of 1.2 at 4-7 psi on some combos. If your setup runs 20 psi or 30 like my car did you are stock with one timing value the entire way from 4 or so psi to 30 psia. Not ideal for best performance. Maybe later ecms can edit the range but i could not. The way we cheat it is to lie about your injector value flowrate to fudge the gram sec vaue thats calculated but that isnt right


second im not gonna argue with you on max power on stock bottom end ls stuff. Main issue is cyl pressure at lower rpms which will lift the 4 bolt heads and cause headgasket failures. Secondary issue is compression forces on the rods which is highest at peak torque and higher the lower the rpm is when making power. Those rods will hold alot of power if you control where the power is. Low rpm high hp is hard. Rpm is hard on rod bolts in tensile force, but thats not where most fail. The rods buckle and bend in ls motors pushed hard in boost. Concept applies to everything but a sbc rod is not an ls rod lol

 

The rods are usually less likely to fail from compressive load. They become weakened by it then high rpm finishes them off. The rod is weakest when the piston changes direction at the top of its travel. Every rod failure I have seen other than hydraulic lock is at high rpm.

The PM rods are also less likely to bend and more likely to shatter.

 

Has the op considered a complete sbc? Or used for that mater? The for sale section sees some pretty good deals. Consider a EBL flash. Works real good, and can often be found used. I built my whole engine second hand save for pistons, cam, lifters and gaskets. Roughly

 

thanks guys, for interesting continuation discussion

Actually, I never knew. I don't really know much about LS engine specifics (years, makes, models, compatibility, etc...) any info you can provide would surely be appreciated.
I saw my first LS in person (really LOOKED at it like I was going to use one) in a junkyard around 2017 right before doing my LS turbo 4l80e swap deal and kind of learning all at once, wired it up for what was needed, then quickly forgot everything (like an exam).
I only had time to learn the basics of comparative anatomy of the engine (by comparing LS engine to elder versions, and of course Toyota and Nissan for example, standout features are common)
Thread is here for that so you can see what I went through more or less (learning experience)
https://ls1tech.com/forums/generatio...x-details.html

iirc, blue/green is 04-06 range year? any engine after 02' is usually 'fine'. Doesn't matter what the displacement is unless we are talking the 5.7 (potentially weak for boost type of engines) but again I am not an expert on which is which. I just know that the L33 is a record holding aluminum 5.3L and ideal for 800rwhp with gen3 electronics using gen4 rods. The basics, always focus on the basics.

I am sure it will run great. However for a daily driver, such lift is generally inappropriate.
The valve springs for high lift and high rate camshafts generally wear and need replacement every 20,000 miles or so. I have read several places including spring manufacturer recommendation.
High lift also increases chances of dropping a valve, valve guide wear, and lends to instability in some cases (when mismatched, surely). It is an edge that street machines rarely require.
Whereas the low lift, slow ramp camshaft ("sloppy stage 1" for example which is what I used) will allow for 100,000+ miles of use while also supporting 800rwhp with turbocharging.

Which makes the high lift camshaft obsolete. There has been a recent resurgence in low lift, slow rate camshaft profiles due to the turbocharger 'phad' you may notice.

ah-ha ! I am so glad you asked.
The 2-bar OS for 411 ECU may contain a hidden table called "afr advance" which simply relates air fuel ratio to ignition timing. Here is an example of how I used it.


Heres the thread where I reveal the features of this table, and it shocks even those regular on the forums
https://forum.hptuners.com/showthrea...l=1#post540960

With this I can achieve any timing at any boost pressure, as it blends with the primary spark table and utilized RPM as the y-axis for discrete control.


We can't use power when discussing rod stress, at least not directly. There is much more to it than torque and power.

You can apply a torque to a (non) rotating object and hold it still. For example, standing on a lug wrench trying to turn a stuck lug nut. You can apply a LOT of torque and still not turn the lug nut.
So now imagine an engine in such a case. The engine is rotating and you are measuring torque, but if the pressure (force/area) in the combustion chamber occurs at the wrong time (early) the rod will experience a high internal stress, and possibly buckle, even though torque output is very low to nothing.
Thus it is possible to bend a rod at very low torque output, at any rpm.
Remember we can always use a negative timing advance, let the heat wash right out the exhaust if necessary. There is really no reason to trap it and bend the rod, this is purely a tuning error.

I've seen rods bend in all kinds of forced induction engines and the one thing that ties them all together is poor tuning or inappropriate use of fuel quality. For example E85 seems easy to over time the engine, generate a very large spike in rod stress without creating much torque, and now you have a bent rod.
It's a tuning issue, purely.
If it wasn't possible to make alot of torque at low RPMS blowers wouldn't work. Keep that in mind, they work just fine
Heres a 2L making 34psi on 93 octane 'tuned properly' notice the negative* of timing is necessary at 'low' rpm to keep the rods from bending.
most people would have used a positive timing number and then blamed the engine for having a weak rod when they bent
https://www.evolutionm.net/forums/ev...l#post11872882


To put this into perspective. A lets assume a random typical rod has a safety factor of perhaps 2 to 2.5 (reasonable range, almost all machines are made this way, each part gets its share of S.F.), thus the materials are designed to withstand far more stress than the engine can provide (for those rare situations where it does for some reason, such as abuse, bad gas, poor maintenance, etc...) which by force analysis alone means that if the factory designed the engine to withstand say 400ft*lbs of torque (we don't know the true rod stress but we could estimate it if we are ambitious), there is a great chance the true holding capability of the rods is near 1000ft*lbs of torque if conditions are ideal (regardless of the RPM). Doesn't matter what the displacement is. Although rod length(angle) will play a role.

another way to visualize this, speaking purely from a design and force analysis point of view, 500 ft*lbs of torque at 5,000rpm and the same torque at 1,000rpm require the exact same pressure to be exerted over the piston area (since piston area is constant, the only variable is pressure). that means torque at 5,000rpm is just as stressful as torque at 1,000rpm, if we neglect the differences due to rpm alone (rotating mass with an angular velocity induces its own stresses which are higher with RPM obviously but we are discounting those for a moment)

 

Another interesting tid bit.
Turbocharged engines typically exhibit high exhaust gas pressure.
This provides a cushion during exhaust stroke which holds the connecting rod to the crankshaft, which helps eliminate chances of rod cap failure in high rpm engines.
thus, a turbocharger applies an rod sparing effect which improves the effective RPM range of the engine, protects the rod.

Toyota 2jz-gte for example, famous inline 3L can do 8,000rpm easily with the turbo attached, 30psi and 800rwhp is no issue.
However if you strip the turbo and run the engine NA it will probably throw a rod at 8k with less than 300hp after a bit of work out
This shows us that rod stress/buckling has less to do with measured power/torque the engine is producing, and more to do with when it is produced and how (the angles and acceleration of the piston /rod at that moment for example).

 

So that is pretty much what I was thinking. It seems everyone has kind of gotten off topic. I maybe new, but I am not dumb. I'm pretty good at teaching myself so lets just take the whole experience thing out of it. I was thinking cam and new heads then SC around 9psi. I'm keeping the bottom end so all the talk of LS stuff is not really useful. I'm also keeping everything I am taking off this vehicle to restore back if I choose. However, I don't plan on selling this car. It is my first Firebird and I love her. I have already started replacing rubber and seals. the car is in amazing shape though and it was garage kept with no rust at all. Thanks again for everyone's interest on topic or not, it is all enlightening.

 

i still dont see how you are doing that. If the spark advance adder is equivalence ratio which is inverse lambda then How does it know what boost its at?

i run near same afr at 15 psi as i do at 30. Theres no compensation for boost or map mentioned anywhere in that thread

while thats true to a point, its not gonna eliminate all the stress from rpm. Some of our cars are running at 1:1 or less boost to backpressure. Some alittle more, closer to 2:1. Poor tuning will hurt parts no doubt but i have not hurt of rod bolt failures in turbo ls motors for those pushing stock bottom ends. Have seen and heard bent rods and broken rods. The guys going fastest on stock block internals and 4 bolt heads are turning 7000+ rpm. They dont run 6000 rpm and more boost, it just doesnt work

 

it is likely no doubt but i have seen the slightly bent rods in ls stuff. Seen them in aftermarket rods too, which can usually bend some before yielding. Its hard to determine how and when rods will break. The ls record is now something like 1400-1500 flywheel hp on stock rods, gen iv type i believe. They wont do that forever and maybe some of that is fatigue from tensile loads getting to it but i’m inclined to believe some of it is just too much compressive force applied to a rod not meant to handle it. Regardless this is all off topic.

honestly a fine plan. I would just do a simple deal for heads and cam, dont get caught up in making big na power. Set up for the blower in mind, let it do the work. You will be happy and it will be relatively easy to tune.

 

you gota use your tuning experience, use your brain. combine the ve map with the afr advance to achieve any timing you want.
say i want 30psi of boost but use the same a/f at 15psi of boost.

In that case simply adjust the VE map leaner and use PE to add an artificial amount of fuel, thereby generating a whole new 'line' of timing values for the increased boost pressure.
I've never had an issue doing this with any amount of boost.
And even if you didn't have that map you could still do it by using a creative implement of IAT or other related timing maps. For example add timing with temperature means you can use a variaster (variable resistor) to add or subtract timing in real time with a dial. I have one of those setup for when I want to throw a couple degrees into it or pull out a couple degrees, or compensate for heat soak, etc...
Simply recall that most automotive sensors work 0-5v or based on a resistance value (with some kind of voltage divider in the ECU) and through these efforts we can achieve any practical application approach.

 

After I said turbocharger allows for higher rpm (thus 7k 8k 9k 10k etc)
why do you say "they don't run 6k and more boost" when I just clearly stated that the higher rpm is desirable,
its like you mistook the significance of the statement? I was not saying to use less rpm, I was saying you can feel free to use more rpm with the turbocharger. ...
boost gives us torque, combined to rpm gives us power. So of course we want the highest angular frequency the engine will tolerate...

 

pretty sure can bend a stock LS rod at 5,000rpm with 6psi of boost pressure, ~400ft*lbs of torque, using E85 and say 32* of timing.
The engine won't detonate. The piston won't shatter. factory MLS gasket will hold.
But every rod may bend. And there isn't much torque, and a fairly high rpm.

It's not always the rpm, its not just the torque. Its the tuning. Pressure is rising well before spark occurs, a pressure spike ensues when high quality fuel is combined with too-early ignition event. The forward rotational momentum of the engine is 'crushing the rod' into the high pressure region, causing it to buckle. If we reduce the rotating assembly mass to zero the engine would spin backwards before spark occurs.
The pressure is much higher doing this than say 30psi of boost tuned properly would exert.

 

Im talking strictly properly tuned thngs. I dont do untuned

 

thats just another way to fudge programming but suppose it could work. Definitely not how i would want to do it. Seems like too much room for error in trying to change fuel to get a new timing value instead of just changing the timing value in a table. Also it would fudge again when iat fuel adder changes as iat increases as intercooler soaks with heat. Or if your water pump fails for air water cooler and temps go crazy, we use iat for safety

Interesting concept tho

i did not mistake anything. What you say here is what i have been telling you. Torque at higher rpm makes ls combos live. Not low rpm. There is some cushion effect with turbo car backpressure but its not necessarily the reason they live

 

lol but how do you know what is tuned? And when?

Dynometers can't tell you that. Driving it with a wideband can't tell you.
Track testing for vehicle acceleration is not a best 'tuned' situation either, its just the fastest setting to get down the track and rarely matches up with what a dynometer will tell us.

In short the only way I know of, to know whether the engine is 'tuned' or not is to use a combustion pressure analyzer in conjunction with gas analyzer and several individual EGT sensors. Or similar. And then to drive the 'vehicle' in many many many different situations (high altitude, low temp, high pressure, low speed, all variations within the scope of application) and compare it to both a physical scale down model (say, in a wind tunnel, or other environments, etc... like they do with planes and ships) and a computer model combined with the empirically generated data.


And none of us has any of that.
So none of us really knows when something is tuned or not.
For example you can't look at a timing map for a particular engine and 'know' whether or not the timing values stated are anywhere near proper unless you have precious experience with that engine's particular nuance behaviors. And even then its just a ballpark.

Which brings us to the idea of ballpark tuning, or tuning to fall within some scope of measurable outputs.
That is we are attempting with the dyno/track/wideband. We take what little data we have and make educated guesses.

guesses

 

First, its two graphs. PE and VE. They work together, naturally.
So if one goes lean, and one goes rich, its the same thing as if one goes rich and the other goes lean.
There is no 'fudge factor' using this technique.
It's not like a scale tune where every single ****ing table has to be compensated for.
There is no large scale, system wide draw back to using this method.
That you seem put off by it's deceivingly simple principle indicates a limited experience tuning a wide variety of computers, which is nothing to be ashamed of; nevertheless be aware that I have tuned around 10 different computers/engines from 10 different manufacturers and have come to use basic principles of how to best utilize such sensors in each case, and it is rarely the same method between them which yields ideal results.
The IAT sensor for example in this case, using a OEM Hptuners style ECU, is completely different from say a haltech or AEM style of iat tuning behaviors. The HPtuners ecu in particular seems better off without an IAT sensor most of the time lol. In fact I drove for many years without one. I also never use a closed loop on my own cars.

IAT: add some perspective
I get the feeling you think of a single IAT sensor, when in reality you need several, and to be able to switch between them instantly, or log them all at once somehow.
For a performance car has multiple stake points for IAT to be taken for measurement.
ex. Before intercooler, after intercooler, before intake, inside the intake, turbo outlet temp, engine bay temp
Furthermore, we often need a steady resistance value handy to clamp the IAT in certain situations.
It depends on the vehicle application, and flexibility of the ECU.
HP tuners(factory ECU) is the only computer I've ever used which does not allow the user to customize fueling based on IAT outside of an Power enrichment state.
And even then it's got a bug where you cannot fully control fuel adding property due to IAT.

This information is general. How you use it depends on necessity.

examples
The factory ECU pulls/removes fuel when IAT rises.
This is because it assumes that air density is decreasing with temp, naturally.
However in our performance applications, we generally do not want the fuel to be removed for high IAT.
Therefore it is useful to disable, or lock the IAT value for those instances. Since we cannot adjust the behavior of the ECU manually this is our only option.
for example I may lock out the IAT for normal driving at 80*F and hold it there. Especially for hot starts in the blinding sunlight when underhood and consequently instantaneous IAT is 150*F when in reality its more like 90*F with the engine running.




that is because you watched "100x tuners tune 100x engines" and those were the results. (sample population vs observation)
Of those 100, say 99 tuners didn't tune it properly and you have no idea which one was the 'correct' one.

Its all about perspective. My opinion is based on what I've seen (very high torque at very low RPM is quite possible using the correct procedure, such as with a blower which can make full torque at 1200rpm)
and I know of static forces within connecting rod, that is,
Force = Pressure / Area, If we know pressure and piston area we get force in the connecting rod given some range of angles (theta), thus an integral of force as the engine rotates exists inside the rod, and RPM has nothing to do with that except that it exaggerates the stress as RPM rises due to momentum being conserved.

RPM is a rod killer. If it was safer to use higher rpm why not 8k 9k 10k?
You make it sound like 7k is the only safe place to be, 5k and 6k is too low, 8k is too high? You have some kinda mental picture here which isn't seemingly represented in reality.
I think what is really happening is 'people'(tuners) are using too much timing at low rpms and the only way they can get away with using so much timing is by running the engine RPM up as high as it will go which helps the piston move out of the way of the expanding gasses that much sooner after a spark.
As simple as it sounds, take a look at the majority of timing maps; you will see several with 'locked out' timing after some specific RPM. like this: 12 13 14 15 15 15 15 15 15 15 16 16 17
When in reality it should be more like this: -2 1 3 6 7 9 11 13 14 13 12 14 15 16 16.5 17

So they both run the same for the last few cells; but if you make any torque before that, the first timing map will damage the engine. Which leads to the rumor of low rpm killing the rod.
Which is absolutely, intuitively incorrect for a mechanical engineer that understand statics, at least IMO

 

thats what majority of us and myself use these cars for. Short acceleration pulls. The tune for a drag race deal gives best performance at the track in mph and et. You can tell when motor is happy with that data and plugs. Peoplehavebeen doing it before computers and sensors lol

Longer term use needs different strategies. Endurance engines do different things. Tune for application. All the data monitoring and cylinder pressure monitoring the world can get you there faster but guys can get there without it with enough time and testing. In the end your parts and gaskets will determine how much it can hold and that is te unknown which has been the point of contention in this wayyy offtopic thread

im not going to booger up this anymore. Sorry to the OP

 

our entire discussion was for helping the op
that was the point of every single post so far

all of the things we discuss are important topics for the op to learn (he is new)
he seems intelligent enough to gain and learn from these discussions

I was never once thinking to myself during this discussion that it was going to change your ideals or thoughts
Only sharing other perspectives, different ways of looking at the same thing
IAT for example was a great topic because so much confusion over the important of IAT is common on every forum.
The meaning of the IAT, what it is you are trying to accomplish, is often very different from how the factory intended to use the same data.
So we take unique approach to similar concepts, we look at the basic installation and derive a new, superior system that is more adequate for our needs.

 

My point is its getting into details outside of the goals of the thread. Max effort will it live lsx stuff is not on his radar. Keeping car original or close to oem style seems to be. If he wants to change that plan then start a new tooic

 

Yeah we already kinda went over that stuff. I told him not to modify the engine wayyy up there.
We got that out of the way, thread is done, now he can enjoy topical discussion of performance, in general, for any who wish to partake.

This may help him learn or have new ideas, incentives, goals, whatever.
it certainly doesn't hurt.
It's not like he can't come back and ask questions or review for answers.
Some of this stuff he may not need for 5 or 10 years, but eventually one day he may remember that time there was this discussion about...

 

Perhaps someone may find it useful despite the title and first post being way different

 

Just the idea of 300-400whp on a stock bottom end, especially without balancing or clearancing, goes against my basic principles. I know it can be done, but with any assurance of longevity or reliability, I would say not. At 400whp, you're talking about 500 at the crank from a 2 bolt block with nodular crankshaft and factory rods and unknown oil clearances, no idea of out of round or taper. If this is just a game of let's see how fast it and go before it blows up? Then go ahead. But if you want this car to last and be reliable, you either need to rethink your strategy or your stated goals. Remember the old saying: "Speed is money. How fast do you want to go?"

 

I think we are overlooking some very important aspects for the power level.

What about the rest of the car? The transmission? The Rear End? how about Brakes?

If you have spent much time on the forum, you will find that the items listed above are all weak spots on these cars. I can attest that the brakes on these cars are, at best, inadequate. For perspective, my Firebird has the 2.8 V6 with 135 horsepower, and I am calling the brakes inadequate. A good 700R4 from Pro-Built with a torque converter to handle near 500 HP at the flywheel will set you back at least $3,000. Now we need to put that power to the ground, and everyone on here knows the stock 10 bolt is a grenade at anything over stock power levels without serious help. But by the time you have the rear end built with a limited slip, a new ring gear (2.XX is no fun with that much power), and at least an axle brace, you're not too far away from an aftermarket rear end from Strange, Hawks, or any other rear end company. For example, a Strange S60 is listed near $2,300 from a couple venders online. Lets tally up the costs of the driveline alone. With the base budget of $5,000 for the engine (this is a Very low estimate for 400 RWHP), over $3,000 for a quality built 700R4, and around $2,300 for a rear end, you are over $10,000 deep in a car that still cannot stop or turn safely. I'm not even going to start on suspension, brakes, tires, or chassis reinforcement, as the prices inflate to a staggering number very quickly. for reference, I am looking at a budget north of $35,000 for my final car, and that is with a 400 CID crate engine from Blueprint with minimal performance "Extras".

What I am getting at is that these cars were designed for stock power levels. Even with the advances over the gone-by muscle car era in areas of chassis and weight, 3rd Gen F-Body design is almost forty years old. I am sorry to disappoint, but if you want 350-400 RWHP, you are better off selling the car and buying an early 5th gen Camaro, These can be had for under $15,000 for an SS. If you really search and don't care about higher mileage, you can even find a manual for under $15,000. If you want to stretch the budget a little further, and closer to what you will realistically have in the Firebird, a C6 Corvette can be had for under $20,000.

Lets hope you lower your expatiation to what the car really is. It's a great cruiser and a fun analog car to drive on twisty back roads. However, it will not keep up with modern sports cars without serious consideration to all aspects of the car. I would replace all rubber components, swap all fluids, tune up the engine, and enjoy the car as is. They're not making any more of them, so enjoy the car and all of its '80s glory.

 

I f@#*& love your post
Spot on, good job

Just wana highlight some details and give some extra info for searchers in the future

This is absolutely the best transmission advice anyone could have given. I will highlight 3 small details
A. don't cheap on the trans, its the most important part of the car, do it right, do it once.
B. I lied, the most important part of the car is the torque converter. The NEXT most essential part is the trans.
C. Pro-built automatics is the ONLY place I would buy a 700R4/4l60e from, on the planet
D. if you get to this point, research 02-06' model 4l80e, a cheaper alternative with stronger internals, a fuel hog, 100lbs heavier, but it will do the job...

This is a major hurdle
most people forget about the suspension, rear, trans, and just focus on the power.
Those are the cars that sit, or break then sit. money pit
point is, plan everything, including what you will do when something breaks.
Plan the trans, susp, brakes, plan the rear... Get it done first, don't **** with the engine at all till its done. Or at least until you have it figured out.

It sucks to hear but its soooo true. Listen to this guy


moral: It's pretty easy to stash 50k in almost any car
keep that in mind novices, there is no end to it, the most you can hope for is to lay out a plan, and follow through to the end of that plan.
Show us your plan first (novices) and we will modify as seen fit, thats what a forum can be good for (collaboration? corroboration? one of those)

Ouch. Honestly, 400 is nothing nowadays. In a 3800lbs or 3500lbs vehicle, 400 is like 250hp compared to the Japanese sports cars (silvia, skyline, rx7, evo, whatever). I am not even joking, and, they come with more than that stock, all original. So if you spent all that money 10, 20k whatever to get 400 or even 500 you are still hundreds of HP and lbs in weight behind the competition of the 90's. Yes, in 1995 you could get a 350 horsepower 2.0L engine in a car that weighs 2800lbs and runs 11's with the stock turbo engine, gets 30mpg. Also those cars are like 5k to 10k to buy complete. So.... yeah do the math

Even if you get a later model with the LS platform, you still fight the weight aspect. And the natural aspiration aspect.
honestly the moral here is... I'm not even sure anymore. I think we all need turbochargers and jet fuels or something. @!#(*#@


This is a great summary and exactly what I had hoped would get posted, thank you

 

eh 5th gens are fat and ugly. Better off finding a ls1 4thgen and doing bolt ons. That will be 310-330 whp in an auto car depending. 330-350 capable in a manual. And 3450-3650 lbs which is much lighter than the 5th.

Even an lt1 4th gen cam only with bolt ons would be fine with 300-320 whp, more with ported heads

but we love our thirdgens. I still stay boost it and not worry about the na building power.

 

This is the absolute truth. I have at least 32K invested in my 87 IROC starting 20 years ago with the original ground up build. Since then, new brakes from Fly N Bye at $1850. Another 700R4 build, did it myself this time with help from Dana and it took 4 times through to really get it right $3,500. This last summer, a new 9" ford rear axle unit from Quick Performance $2,600. In the next two years,I'll be preparing to build another small block. A 550hp 400cid this time with a Dart SHP block and all forged internals, expect to spend $5,000 to have the short block built by Somer's Automotive Machine and another $1000 having my Trickflow G2s rebuilt and prepared to go on top. Like I said, speed is money. If you love your car, it's worth saving the pennies to do it right.

By the way, my car with its built TPI is .3 quicker in the 1/4 than my friend's 2010 with auto trans. With my suspension and chassis mods, my car will also run circles around the 5th gen. Once I have the new motor in, I'll put it up against the new Vette. For me, it's 3rd gen all the way, even though I could buy a new SS if I wanted. I work on them and all new GMs all the time. I personally think they are plastic junk.

 

My initial response to the 4th gens was excitement. The 4th gen Firebird was modeled after the Banshee and seemed like it could really be a great performance car. My son even bought a 2002 Ram Air. But then I started working on them. They are nothing like the 3rd gen with its body by Fisher Coach Works. The 4th gen, GM bragged, would be a leap forward in body design. What they should have said is that it was the start of their new effort to save money building their own cheap plastic bodies. The result is a bulky chunk of plastic crap. The 4th gen doors are totally plastic. Have you ever tried replacing a window regulator in one? What's also cool is when the outer door skin starts to separate from the door body. Then there's the interior trim that is all flimsy snap together plastic. I rarely see one of these cars that doesn't have switch bezels hanging loose with broken retainers. Real junk. Best part is, all that plastic and the 3rd gen with its all steel body and iron V8 is lighter. Swap on aluminum heads and water pump with headers and we are lighter yet. As far as the LT1 is concerned, have fun working on that Optispark ignition. I cringe anytime one of those shows up. All of this, and the 3rd gen, with adequate power added under the hood, outperforms the 4th gen in every way. Oh but the 4th gen does have a smoother ride. And yes, I'm done with my rant.

 

See, what you need is a 305. Everyone knows the 305 was sooper underrated.

 

lol i never had any issues with my 4th gen 99 TA. Thought it was a fantastic vehicle and one of the best meanest looking cars ever made. I cut my door to allow changing window motors in minutes so thats possible to do. They are a pain to work on motor wise as its best to drop the entire k member to do major engine work. But they ride nice handle well and ls power makes them fantastic. Never had a lt1 4th gen to compare but tuned several and rode in friends cars. I think they are decent too if you find one in good shape. Just replace opti with the 24x ls1 pcm system

 

LOL. Maybe I was a little harsh. I have a couple that come in that are pretty nice cars. These are the two that are really well cared for. If the LT1 in the 95 Z28 ever needs wires or distributor, I'll hand it off to one of the line techs, lol. My son's ram air was beautiful. He bought it from a middle aged woman with 22Kmi on the clock and in mint condition. He kept it that way for the years he owned it. With the ram air LS1 and T56 trans it was fun to drive. My built IROC would tear it a new one. We figured about 80hp difference between the two. The one mod we did to the TA was KONI yellow shocks and Eibach Proline springs. It did ride pretty nice after that. He sold it with 28Kmi for more than he bought it for. Sadly, he got a call from the cops about 4 months later. Seems the guy he sold it to had never transferred the title. He was a meth dealing con man who ended up in a high speed chase in the TA. It was torn up bad. I helped as much as I had time for to piece it back together but it was never the same. It broke my son's heart to see it and then have it sit in his garage like that. After spending $3,500 to have the broken T56 rebuilt and after I rebuilt the ripped apart engine harness, he sold it as a fixer upper, still needing body work and a rear diff rebuild. Very sad.

 

no joke, thats a terrible job to do on those cars with any shorty header and probably with manifolds too. One car i tuned had issues with breaking up due to e3 spark plugs. Took off dyno and got new ngk plugs with correct gap and had the shop tech do the job, took like 5 hrs lol