I have an '85 IROC-Z and I want to know if I can get 400 to 500 horse power out of my 305 TPI. if I can what do I need to do it. If i can I want to eventually run 10's in the 1/4 mile. Any suggestions would be good.

 

get a bottle of NOS, that would be the only way to reach those HP numbers with a 305 TPI.

 

Uh wrong!
You can easily get 400 horsepower, check out the article called "305 bulidup".You could also add a supercharger along with some other mods,heads,cam,etc.

 

The key part of the original question is "TPI". The 400 hp 305 build-up, Rob, was carbed. There's a big difference there.

In order to get 400+ ponies out of a 305, you have to spin it up pretty tight. TPI doesn't lend itself to that without major changes.

Power-adder is your best choice to accomplish that objective. 10's - well, that takes a lot of work, and not just in the power department.

 

Some other things i know of that you'll probably need to make your IROC 10-second capable: new tranny, 12-bolt rear, wheels/tires, heavy duty clutch if this is a manual car, and lots of engine work and a power adder. Unfortunately, not enough R/D has been done on the 3rdgen platform to make 10-second cars cheap or easy.

 

no way in hell the stock pistons and rods could handle getting a 305 into the 10's you would have to go carb, no way in hell with a TPI. plus you'd need to spin that engine to the moon and have like a 3,500 stall and TONS of NOS inother words its not realistic. 350 is a COMPLETLY diffrent story tho.

 

It's MORE expensive to get a 305 bottom end to hold up to 400+ ponies than building a 350. It would actually be cheaper and easier to get a 350 to make that power and the power adder wouldnt have to be as severe to make that power, hence, your motor would last longer. I'm building a naturally asperated TPI long tube runner motor that will put 400+ to the back wheels / 475hp at the crank and about 500+ ft lbs of torque at the crank. If you want the specs to my combo, look at my post "What are your opinions on my new combo" in this section.

 

I know it can be done. I want to know how. I want to stay with the 305 and if I can't do it I will go to a 350 but that will be the last resort because I want to stay original engine.

 

No way in hell with a tpi? I've seen it done. Infact, there's a guy running in the 9s with his 305. Anything's possible. It's just a matter of how deep are your pockets? Also, the 9sec 305 IROC generates a lot of attention when mentioned for obvious reasons, that's a plus for doing it.

http://www.tta89.com/videos/smitty/305Iroc.mpg

download that. That link should still work. I also have another but I'll have to get round to putting it up somewhere.

I'm in the process of building my 305 up. I'm adding a procharger at the end of the year and it should be in the high 11s. I'll keep everyone posted on that one.

Regards

Robert

 

It can be done. a 'charger would be a good idea, 305's like lotsa boost.

 

Didn't work for me

 

you can stroke it to 335 cu.in with the 400 crank.
but still, not worth it..
you could get a 302.. witch has different bore characteristics..
that would be worth it and rare.

 

I know it can be done to a 305, but I don't know how. I have the time and the money I just don't know where to start. I need to know what parts or work needs to be done so I can start. I have the money and the time, I just don't have the Information I need to start.

what are the best heads for a 305 TPI?

what is the best cam?

what is the best exhaust system(headers, muffler, pipes, and catalytic)?

What is the best charger for a 305 TPI?

Anything would be helpful!

 

originally posted by TempesT68:
That could be debated, there are "go'round" racing classes that require cheepo parts, stock rods, two bolt mains etc, that are making major power. There are also lots of Buick turbo Regals with smaller displacment (231 CID) going 11s and 10s with stock shortblocks. There is no reason a 305 couldn't do it as long as it isn't over revved or detonated. "Good" parts will of course last longer.
WRONG! The 9 sec 305 P Smith ownes (and plenty of other quick cars) is not only using TPI but he used a ported stock TPI base, ported stock plenum and long tube runners to go not only 10s, but 9s.
Wrong again! The 305s small bore and long stroke naturally lends itself to lower RPM power (and better drivability) instead of high RPM power. You build long stroke/small bore engines to make power down low, and large bore/short stroke engines to make power up high. He used a relatively mild 2500 RPM stall converter, and no NOS or any other brand of n2o (nitrous).
The moral of the story is that just because you haven't done it or seen it done doesn't mean that it can't or hasn't been done.


The 9 sec TPI 305 mentioned above is always evolving. I hear now that he is using a turbo system.


When going 10s he was using this:

Vortech R trim supercharger 16 PSI boost.
Custom liquid to air intercooler.
A S & M 52mm throttle body with airfoil, Stock ported plenum, A S & M long tube runners, extrude honed stock manifold base.
30 lb/hr injectors.
Stock in-tank fuel pump, Bosch in-line booster pump.
Stock ECM with Accel Power Processor.
MSD 6AL with boost retard, stock indexed distributor, heliwound plug wires.
Lingenfelter 272 hydraulic roller cam.
AFR stage one heads, ceramic coated valves, stainless roller rockers.
1990 305 block with splayed four bolt mains.
Ceramic coated JE hypereutectic pistons, .030" over.
Mechart stainless boxed rods.
Forged crank.
Headman 1 5/8" headers, dual 2.5" pipes, Sonic Turbo mufflers.
Modified th700r4 with B&M guts, Art Carr 10" non lockup converter (2500 RPM stall).
Dana 44 rear, 3.54:1 gears.
Boxed rear control arms and torque arm, tubular panhard rod.
Koni adjustable shocks & struts, aftermarket springs, 1.5" spring spacers in rear springs.
Polyurethane bushings.
Global West subframe connectors.
Removed front swaybar at the track.
Dot legal drag tires.
Weight with driver 3745 pounds.

********************
On his way to running 9s he changed to the following:

Vortech T trim, eight rib belt, custom tensioner, 24 PSI boost.
Forged Crower 6" rods.
Wiseco forged pistons.
Comp Cams hydraulic roller cam, 0.530" lift, 215°/222° duration @ 0.050".
Extrude honed Trick Flow Twisted Wedge heads.
A S & M 58mm throttlebody.
52 lb/hr injectors.
Stock in-tank fuel pump with SX booster pump, SX fuel pressure regulator.
Electromotive Tec II computer.
Hooker 1 3/4" long tube headers, Dr Gas X pipe, Flowmaster crossflow muffler.
Art Carr guts in an 88 700r4.
Dennys Carbon Fiber Drive shaft.
9" rear end, 3.50:1 gears, Moser axles.
10" X 28" ET Drags.
Weight with driver 3648 pounds.
Plus lots of little custom tricks, mods and fabrication not mentioned above.

 

A friends pointed out that the link no longer worked. I'll have to get round to putting them up somewhere. It's a pretty awesome car.

What compression ratio is he running? Anyone know?

Rob

 

I don't know what he is running now with the turbo setup, but at the time of the 9 sec combo above it was 8.8:1

 

Let's get one thing straight: Dave, are you willing to go with a power adder like supercharger (I assume you are, by your last post), or do you want to stay NA? Either way, it's gonna cost ya.

This "305 Wonderboy" you all seem ga-ga over is hardly running 9's on a stock engine. About the only thing factory about his combo is the block, plenum & base - everything else is upgrade, and he spent some signficant coin on the parts that are stock! He probably has more than 15 grand in that engine (the coated parts alone probably cost more than most guys have in their entire engine).

And you're trying to save money by staying with the 305, Dave?

Face the music, guys: There's no replacement for displacement - including power adders. If you want the cheapest power, increase the displacement. Any other route will end up costing you more money sooner or later.

 

Well excuse someone for trying to be a little different. If someone wants to do something that's a little different from the norm let them do it, it's no sweat off your sack.

As for superchargers. I would go with ATIs D1sc with the 3 core intercooler. You'll be able to run a good amount of boost with that. Remember also that if you do decide to get a bigger engine that you can still use it so it's hardly money wasted.

My engines just getting put back in the car as we speak and I'll let you know what sort of improvement I got with what I have done to it.

Regards

Robert

 

originally posted by five7kid:
No one said he was! but he is doing it with stock displacement and a production block which was his plan in the first place.
That is true for most 9 second cars, 305 CID or 505 CID.
Again, that is true for most guys running 9s.
Those guys (the ones with less than $800 {approximate cost of ceramic coated pistons and valves} in their engines) are not running 9s. They are probably going 12s or 13s at best.
I think I can answer that in his own words, "I know it can be done to a 305, but I don't know how. I have the time and the money I just don't know where to start. I need to know what parts or work needs to be done so I can start. I have the money and the time, I just don't have the Information I need to start.
what are the best heads for a 305 TPI?
what is the best cam?
what is the best exhaust system(headers, muffler, pipes, and catalytic)?
What is the best charger for a 305 TPI?
Anything would be helpful
"
hhhmmmmm, Do you run 9s with your five7 A little five0 can. Maybe there is a replacement after all. It gets old when people slam what others are succesfully doing. It also gets old when people slam what others want to do just because it is different than the way they would choose to do it.
By the way, Dave was only seeking to make 400 - 500 horsepower. This "305 wonderboy" was making closer to 600+. Dave has some room to grow.

 

Here I have the Video of Prestons Car up on Lastgen

http://www.lastgen.com/videos/9seciroc.mov

 

there is no replacement for displacement. proven time and time again. take that 305 and do everything he has, do it to a 350, it will be faster. plain and simple fact, that is all five7 was pointing out. five7's 396 runs I think 13's with a smooth idle, if he wanted to run 9's I am willing to bet with the right amount of money he could do it, and definately better than a 305, because of the mere fact that he has more cubic inches.

i think your way out of line irockz4me picking apart five7's post because he has helped A LOT of people on this board, he has been there done that and was offering his opinion on making 400-500 hp cheapest.

 

I carburated 350 with vortec heads and a victor jr. intake is the cheapest way to make that power Naturally Aspirated. For a little more dough, I will make that power all motor with a TPI setup. Check my combo in the topic I posted. Theres all the specs you need to make that kind of power NA with a TPI.

 

originally posted by zerogauge:
So it's ok for him to pick other peoples posts apart using statements no one even made?
Last time I looked at this post I was one of the very few to actually provide what Dave was
asking. Maybe I'm just wrong
He asked a specific question with specific requirements that he wanted to make 400-500 HP/run 10s with a 305 He didn't ask "what is the cheapest way to make 400-500 HP".
I didn't try to talk him out of it, or lie to him and tell him it can't be done or that it would be cheep or done with all stock parts. I didn't tell him it could not be done with certain parts when it can and has been. I didn't tell him a way to make power with a larger displacement than he specifically requested.
I gave him a somewhat complete rundown of what it could/did take to meet or exceed his goal within his stated requirements. He specifically said he knew it could be done with a larger displacement motor, but he did not want to go that route.
I stand by my posts accuracy(all of them) but since I'm "way out out of line" I appologize and I'm outa here!

PS By the way you are correct about doing identical types of mods to a larger displacement motor making more power all other things being equall, but that isn't what this thread was about. Also displacement is only a small part of the equation as this 9 second 305 we are "all... ga ga" about proves. By the way it idles like a stocker too.
If there really is no replacement for displacement then how come an 800 CID mountain motored car doesn't beat a 400-500 CID supercharged topfuel, nitro funny car, alki funny car, or promod? hhmmmm. Maybe there are other things to consider besides just CID.

 

VERY DOABLE...

http://www.angelfire.com/nb/thirdgen/400hp305.htm

 

i thought i read cheap in there somewhere, and that 305 is not by any means cheap...we all agree on that. we also all agree a larger engine could probaly do it cheaper, but if he wants to use a 305....then so be it. I SWEAR I read cheap up there somewhere....so I apologize. I believe i was still thinking about the post about getting in the 12's for cheap.

Later.

 

and just so you know, I'm not just trying to kick five7kid in the *****.

I agree with a lot of what he said in his first post, with a few qualifiers...
Originally posted by five7kid: I agree this will make a big difference in the rest of the combo needed. Long tube manifolds function differently than short runner manifolds. This is not as critical if using a centifugal supercharger as it is when running naturally aspirated though. It is still important to consider however.

I guess that (spin it up tight) is a relative term. Naturally apirated, you would probably have to go 7000-7500 RPM to get 400+ HP from a 305. From a performance stand point that isn't unusually high. I once built a '69 302 with similar CID (but the opposite bore stroke relationship) that made 400+ HP but at well over 8500 RPM. As long as you fill the cylinders effectively, a long stroke small bore engine is more powerful at a lower RPM while the large bore short stroke combo is more powerfull at a higher RPM. This considered a 305 doesn't have to be spun as tight as some other combos. A 305 has much lighter pistons than a 302 or a 350 so that is a small help too (not as much stress given the same RPM). Something to keep in mind, because the 305 has a long stroke and small bore and therefor will be more naturally suited to lower RPM, and less naturally efficient at higher RPM than most engines, is the formula that expresses horsepower. Basicaly it states that a given amount of torque at a higher RPM = more horspower than it would at a lower RPM, and that increased torque at a given RPM will increase horsepower at that RPM. So you can increase torque at any RPM and horsepower at that RPM increases, or you can increase the RPM where that torque is made to increase horsepower. If you try to increase the RPM (to a very high level) where a 305 makes power you are fighting against the natural tendancies of the motor. You are better to increase the torque as much as possible through out the usable RPM range. A stock runner length TPI most deffinately does not lend itself to high RPM. This is mostly an issue when naturally aspirated and is not much of an issue when using a centifugal supercharger.
I agree completely.

 

Okay, let's all take a deep breath...

Any attempt at flaming me for not wanting somebody to be "different" can only be ignorance. Read my sig, for pete's sake.

As for nobody saying it was a stock engine - well, Tempest said you aren't going to make 400 hp with TPI and stock cast pistons, and RMK replied quoting him and started all the Wonderboy talk as if that proved Tempest wrong.

I'll back off on the "saving money" part. I probably confused that with a similar question on another post.

Look, there's "different" (and Wonderboy qualifies), and there's "smart" (Smokey Yunick qualified on both counts). You don't see a lot of 10-second daily drivers out there, and I'm fairly sure none of them are NA 305's (Even Wonderboy isn't NA). Most of us start out with lofty goals and are slammed back to earth by the laws of physics - some learn from that, others try to spend more money to get those laws repealed. It don't work.

10's are expensive (12's are, for that matter). There's proven ways to get there, and "different" ways. "Different" will cost you more money. When I see an '85 Camaro with a Buick 455 at Bandimere that's slower than my '57, I tend to revert back to "proven".

I'm not trying to flame or bust anybody's manhood, just trying to keep things realistic.

Besides, people who think they know it all really annoy those of us who do...

 

It's just hard to keep quiet when someone says that something can't ("no way in hell") be done, when it has and you've done it or seen it your self.

 

That post was referring directly to using stock pistons and rods. It could probably be done with stock rotating parts, but certainly wouldn't last long. I inadvertantly took mine to 6300 a couple of weeks ago, thought sure I had killed it. But, it's still running fine.

Like Zero, I'm sure I read something about keeping it cheap. It must have been edited out.

You should also be careful of what you have "seen". People don't always tell you everything, especially in the pit area.

 

well... the point to understand about everything is that anything can be done. I've read about a few guys that reached the 9s with a 305. it takes a lot of freakin work, and after a certain 1/4 time, it gets freakin expensive... for instance from now-12s is expensive, 12s-10s is insane.. anything lower requires sponsoring. 305s love boost, but the problem with the TPI is if you're using MAF.. the sensor isn't big enough, so after you reach a certain cfm, the sensor doesn't know what to do. It's really limited and they don't make aftermarket ones i don't think.

 

Actually it was the "you would have to go carb, no way in hell with a TPI." statement that was refered to mostly. I do beleive it could be done with a stock pistons and rods as long as no detonation was present. The small bore 305 pistons are much lighter than 350 pistons and thus the pistons, rods and crank are less stressed at the same RPM. A supercharged/turbocharged engine also tends to be less brutal to the crank and rods than a naturally aspirated engine of the same power level at the same RPM. Detonation is the big issue, and if you're detonating you are already screwing up, stock pistons or not. Forged will just take it longer, but will eventually fail too. As I've mentioned before many Buick turbo cars (231 CID) are going 12s, 11s, and even 10s, with stock short blocks. The smaller internals allow more abuse on stock parts than stock larger internals can handle.

There very well may have been a request for a "cheep" way to do it in the thread before I read it that had been edited out. I never saw a request for "cheep" in it though. May have been, or may have been in another thread, seems like theres always a "newbie" wanting 500 HP out of his stock engine for $500 or less

When I use the word "seen" I mean just that. What I have seen first hand, not just what the car owner or someone else said. I agree completely with your statement that you can't always go by what you are told especially in the pits. I have been guilty of not being totaly honest in the pits in the past just for fun. I had set up a 406 in an 83 TA back when they were fairly new. I used all of the stock externals (valve covers, air cleaner, etc.) It still had AC and all emmisions equip in place. It even still had the CCC carb (although slightly modified and tuned). The only way any one could easily tell that it was a 406 was the harmonic damper, and no one noticed that. The car had been lowered and had subframe connectors, other than that the chassis and body were all stock (other than a little unseen lightening) with stock wheels and tires. I ran it at the local 1/8th mile going right at 8.0 @87MPH It got lots of attention after a pass, and when someone asked I always said it was just a hopped up 5.0 HO. Most bought it. Some just scratched there heads A few of the more "worldly" didn't belive it for a second., they were the only ones that I told what it really was.
But these days I pretty much share everything. It's more interesting that way. As far as the other guys ride, I take what he sais lightly then look for myself if/when I can. I especially like talking to the pony guys (that haven't met me yet) in the pits. They don't know that I've spent about as many hours wrenching on Stangs as anything else. They are used to telling "fibs" to "camaro/firebird only guys", ricers, or others that don't know much about the blue oval. They love to say "it's all stock except a Flowmaster". (yeah right, and it's running low/mid 8s or so) Then I start asking them questions about all the aftermarket parts I see on their car, like "what did you do to compensate for those Motorsport 30 lb/hr injectors?...Matched MAF?... MAF signal interceptor?... custom chip module?

 

Originally posted by White Ninja:
You are correct, the MAF is an issue, but not a big deal. The sensor, as calibrated from the factory, can only measure up to 255 grams/second. There are many ways to compensate for this though. Bosch at least used to make a 4"" hotwire MAF. Stock is 3" I haven't seen any for a while, but then I haven't been looking either. You can also modify a stock 3" unit to enlarge the duct. I have done this to a few in the past. The way the MAF measures air, it is easy to increase the flow ability of the meter while spreading the airflow measuring range. All of the air flowing through the MAF is not directly measured. Only the air passing through the venturi in the center of the meter is measured. The air flowing through the main duct but around the outside of the venturi is not measured. The meter is thus calibrated to that ratio of airflow through and around the venturi. You can cut the outer duct off of the meter and epoxy a larger duct (like 3¼",3½",3¾",4" etc.) in place. This will change the ratio of air flowing through and around the inner venturi, while effectively "leaning out" the calibration (to compenstate use larger injectors and/or custom PROM). It increases the total amount of air that can pass through the meter before it electricaly tops out, and reduces restriction in the intake path. The down side is that it reduces the meters resolution, so if you go too big it will harm idle quality and mixture accuracy at lower RPM.

Another fix is one that a lot of Buick turbo guys have used for years. Their stock meters also measure only up to 255 g/s. They simply over compensate for the air/fuel mix in the PROM calibration. If they really want a 12:1 fuel mix they just program the PROM table at the highest air measure possible(255 g/s) richer, like for 10.5:1.

Another similar but mechanicaly based fix used by many turbo and supercharger guys is the FMU. It increases fuel pressure at a rate based on boost level to add the addition fuel needed.

Another fix is an "auxilary fuel injector system" That turns on additional injectors as needed based on boost, or boost and RPM.

Another fix (that I am using on my supercharged 86 IROC) is a programable "piggyback" computer. It retains the stock computer and all of it's ancillary devices (like emissions controls). It uses a 2 bar(up to 15 PSI) or 3 bar(up to 30 PSI) map sensor and has programable tables for additional fuel and timing retard or advance based on load, RPM and boost.

Another fix is to install an ECM from a stock forced induction vehicle, like a Buick turbo car, or better yet a typhoon/syclone.

You can also install an aftermarket stand alone system like DFI, F.A.S.T., Electomotive, Haltech, etc.

 

I never actually said that it would be cheap to get over 400 horsepower out of a 305. I am not one of those "newbies" that thinks it is cheap. And if you think I wont do it, just wait till you hear of a guy named david running his 305 TPI down in the 9's from Texas!

 

The guy that used to be on here named TheFormula has a 305 TPI with about 450hp that run 12's. He has no NOS, its mainly all the supercharger.

 

Updated Video Link

 

After reading ALL of that, I went back and re-read the OP.
"I want to know if I can get 400 to 500 horse power out of my 305 TPI."
YES.
"if I can what do I need to do it"
Key words here are 305 TPI and NEED. Short answer is: power adder, more fuel, strong spark, and more exhaust flow.
"If i can I want to eventually run 10's in the 1/4 mile."
Since this doesn't say "ten flat", we'll go with a 10.999.
In addition to the power, you need a stronger transmission, a custom driveshaft, some rear axle strengthening, probably via replacement, a bunch of suspension changes, some chassis stiffening, and some sticky rear tires, with skinnies up front.
"Any suggestions would be good."
You might get there with your stock axle if you thoroughly beef it and stay with an auto trans, but an auto will eat 9% more power than a stick, but will be more consistent.
The engine will live longer with forged pistons.
The power goal will be easier to meet on pump gas if you stroke it and get some Edelbrock E-Tec heads.
I suggest you use boost instead of nitrous.
I 100% back five7kid on everything he's typed in this thread. All others can step off. Permanently.

 

Wow a very old thread.

Boost is your friend. Stronger tranny will help but some guys have pushed stockish trannys into the 10's for a few seasons without breaking them. A mild rebuilt 700r4 will easily last 10 second power if the launch isnt that brutal. That will stress the tranny and drivetrain alot more.
Stock rear will hold the power, that is 10 bolt with the later style 28 spline axles. I"ve been 9.7's with my stock 2.73 gear 10 bolt and i've been well into the 10's for a good many passes with the 3.42 10 bolt i had. Alot of mid high 11 second passes on motor as well. Its held 1.41-1.45 60 foots but most of mine range in the 1.5-1.6 range.

10's is near 450-500whp which isnt all that much to get out of a nice boosted setup.

 

 

Orr, where's your IROC kills a Coyote 5.0 vid??!! I think it's over due for a post!

 

I understand your attitude. I saw a guy recently drag racing a turbo V6 C4 corvette. It was interesting to say the least. My dad also built a mazda truck with a 327 cu inch 4.3 litre v6 block which is faster than most cars ive driven.

If you're gonna go about this engine build seriously the cost difference between a 305-350-383 is not very large. You don't get into the real expensive stuff until you are doing 391+inch 350's or 421+inch 400's. 434's and larger especially. Its hard to feed em. Heads are exotic$$.
The first thing that comes to mind is build a 421 small block but that has been beat to death so.....

You need to find a good machinist. Tell him what you are after.

Your cam and heads are gonna depend on your application namely;
displacement, Powerband rpm, NA/blown/N02, intake, gearing.

I think your goals will require good parts. Forged crank, H beam forged rods, forged pistons, aluminum heads, roller cam, etc.

Do you care at all about streetability. Be serious now. If you are gonna drive this on the street with any kind of frequency the answer should be yes. There aren't many crazies like me who will put up with driving crazy cars daily.

 

Is it me or is that camaro's ET 10.89 in the video? It's hard to see but certainly looks like 10 seconds.

 

yeah its 10 something. That thing has got some wicked hook! At first I thought "bullshit" this was speed up like knight rider" but after watching it a couple times it seems legit.