Ok got a few question's for people that know TPI and all its alternative intakes.

So is a stock tpi restrictive to hp/tq along with rpms or is it just restrictive to rpms?

say if i was to stick a completly stock tpi unit on a 406, and if say it put out 400hp 550tq, if i stick on a HSR will it bump up my power output along with how high my engine will be able to rev? assuming i have good flowing heads.

If you wanted the ultimate, tire burning street car and you arent doing any highway racing just pure dig stuff, would you be fine with a stock or mildly ported out tpi unit or would you still benifit from hsr even though the motor wont need to go up high?

Yes basically the same question but im trying to make a clear point. Thanks.

 

anyone?

 

I can tell you this, I had a LT1 intake on my 87 Trans AM and I thought it ran great, but it was a turd. I put the HSR on it and wow did it ever wake that motor up. When I punch it from a dead stop with the LT1 intake I would only get a chirp out of the tires. Now with the HSR I can annihilate the tires. It woke the car up completely in all rpms. So in my case it definitely was a benefit to my car with the LT1 intake, but as you have the TPI still it might be completely different.

 

This may help answer your questions:

http://www.compcams.com/Community/Ar...?ID=1737510521

 

i wish the link included price, im debating if its better for me to stick with tpi and get new base manifold/runners and port everything and extrune hone everything, if i should just port all the stock pieces an bit, or just get hsr. I know hsr technically isnt legal, but if i just have a sniffer test i WOULD pass emmisions correct, of course if everything else is good.

would there be a total diffrence of how much the intakes flowed if they were to of used a 400/406?

 

There's a thread I was just looking at the other day, comparing stock TPI, ACCEL Superram, TPIS Bigmouth and TPIS Miniram on a 383. The numbers they were getting were very impressive. Ill try to find the thread at post back with the name and board.

 

thanks, your not meaning the comps cam one are you? lol. btw how much did you spend on your intake? do you like it?

how high should the engine rev to if you are just going be doing stoplight to stoplight racing? or for when someone flys up to you trying to pass you?

 

Yeah, thats the one. LOL. Cool that watajob thought the same thing. My intake was pricey(Accel super ram base $700, TPIS runners $400) but you can probably find the same parts cheaper. The part of my system that really makes it work is my cyl heads. The twisted wedge design works very well with the my high flow TPI. These heads are pricey, about $1500. I also spent alot of time porting and port matching every part to make the system work at its best. The bottom end is also built to match the top end at $1500 on parts and machine work.

I probably went further with my cam than most would want to. The cam I originally used with this combo was an SLP part. The specs were something like 223/230 @ 050 503/512 112 LSA. That cam made this motor cook. The new cam made it alot stronger above 3,000 but cost me some low end torque. Since torque is the TPIs strong point, I wouldnt necessarily recommend this choice to others.

I built this motor to test the horsepower limits of the TPI system. I intentionally avoided such things as siamesed runners because that changes intake geometry so its not really TPI anymore, IMO. I am very pleased with the results of this experiment. I have kept it as is for 11 years because every time I think that maybe its not fast enough and that I should build a hotter motor, it scares the c**p out of me again and I am reminded of how fast this car really is.

As far as RPM limits and performance, remeber that HP is TQ x RPM / 5250. So high rev power makes a car quick just as much as low end torque does. All it takes is the gearing to get it to the ground. I find that my wide torque curve and high rev power work very well with my custom built 700R4. It holds very well to 7,000 so I can really make use of those high revs. Shifting at 6,800, it just misses the rev limiter and hits the next gear at about 4,500, right in the power band. I love it!

 

thank you, and wow that is pricy! I kinda want to stick to a stock tpi setup, just with some porting because its cheaper and you get plenty of torque, another thing though is that i know i want something that will also pull me fairly decent from a roll, so im thinking i might just go hsr. Arent they around 800 bucks? It seems like that will probaly be the best choice for me, but i can still pass emisions with a hsr if its just a sniffer correct?

Also when you install hsr, does the car need to be tuned then? I'll probaly end up putting a good chunk of mods on my 305 and then swap it over. Arent stroker kits about 1k? is it worth to stroke a 400 to a 406 for that much or is the money better spend else were?

 

FWIW, a 406 is achieved by engine bore, not stroking.

I'm no expert by any means, but one thing about a long tube runner system(stock or even aftermarket TPI), is it will always have a hard time breathing at higer RPMs than a shorter runner system such as the HSR mainly because of the lenght of the runners. Of course the aftermarket TPI components are going to help, but at the retarded expensive (IMO) cost for the base intake/runners, it sure makes other systems like the HSR look alot more practical.
I personally LOVE the long tube runner look though, and it's low end torque advantage seems to make it ideal for a street driven car (also, JMO).
That is mainly why I chose the FIRST fuel injection setup for vortec heads. I got a great deal on a basically new setup (cheaper than buying a new HSR or aftermarket TPI base/runner setup) although I haven't been able to install it yet on the 87 L98 w/vortec heads and ZZ4 cam that will eventually make it in my car (some day, shoulder surgery put everything on the back burner for this year ).

It should make for a fun street driven motor though, at least that is my plan

 

thanks, what exactly is the diffrence between boring/stroking? defintly, runners alone are like 400 bucks and it seems even when you replace nearly every part of the tpi unit with origional looking parts you still need to port them to have good results. I to also love the look of TPI, but ya hsr is a better deal i think lol. i wish i new the price of how much it would be to get everything port matched, extruded horned, and get the runners siamesed. it might change my mind then. sorry about the injury.

 

Ok I think to answer you question theres a few things I have to explain first. Now im sure youve heard a lot of talk about flow rates and TPI being restrictive above certain RPMs ect but I think you may be unclear on some points of what all that actually means. You see the objective is to get as much air into each cylinder as possible. Now ignoring a few factors lets say the most air you could get into a cylinder N/A is the volume of that cylinder (also known as 100% volumetric efficiency). Now lets look at the intake by itself and its flow rates. Flow rates are usually measured in CFMs under some specified pressure. The key word here is that it is a flow RATE. To get the actual amount of fuel and air that actually flows you have to multiply this flow rate by time. The amount of time the intake has to flow is determined primarily by the motors RPM. So assuming the intakes flow rate cant change as RPM increases the amount of air that could potentially flow into the motor decreases because there is less time to allow air to flow into the cylinder. Eventually there comes a point where there is no longer enough time to flow enough air in to fill the cylinders and power will flat line or just start to drop off. Now lets compare TPI on a 305 and a 400. The intakes flow rate is the same and the RPMs will be the same but because the 400's cylinders displacement is larger the 400 is going to hit the RPM where the intake can no longer flow enough air into the motor to fill the cylinders well before the 305 would. Can you rev beyond that point though? Sure. What would happen if you slapped a stealth ram on there in place of TPI? The intake would flow better and allow you to build power until even higher RPMs due to the higher flow rate at the expense of some low end torque. If you plan on remaining in the low RPMs this isnt a big deal and TPI still has an edge because it is tuned to the low RPMs though you would definitely benefit from aftermarket parts.

I know what your saying about how expensive it is but really a well worked stock base can perform as well as an aftermarket one the only thing that really should be replaced is the runners. Also yes theres a lot of talk about a ton of money and hours of welding/porting/siameseing to make TPI perform in the high RPMs but thats what happens when you try to make something do something it was never designed to do. If you only want to build up your low RPMs TPI is a great way to go and you could use all stock stuff but unless you truely only want low RPM performance the stealth ram may be better suited to match the 400 or at least a modded TPI set up.

 

A friend of mine is selling a VERY fresh complete 406 (less than 500 miles). It has a stealth-ram, aluminum PRO-Topline 200 cc heads, Comp cam -229/245, coated 2210 longtubes, computer/harness.... basically all the bolt-ons and goodies complete to drop into any thirdgen. He's doing a LS swap. If anyone is interested, I can get pics/prices etc...

 

Sounds like a good deal for you.

 

The MAF system can adapt to a certain extent because it manages fuel delivery based on the actual measurement of incoming air. Speed density systems must be retuned with any engine mod as they rely on a base fuel map written for a particular engine and VE.

Almost any engine can be made to pass a sniff test. A big enough catalytic converter or two or three can process the HC, NOX & CO. With a well tuned motor, CO shouldnt be a major issue and NOX will only be an problem if youre running too high cyl temps. HC is the problem with most performance builds because of cam overlap. If you stay with a milder cam, this can be managed as well.

 

I've got LS plans of my own, otherwise I would already have that motor.

 

... im still trying to decide between keeping tpi stock, keep tpi but do mild work, or just throw on hsr or similar intake.

I know i REALLY want low end torque, its an absolute must for me and i dont wanna lose any of that, but mid-high rpm range power would be nice to...

im going start working on the 305 and then sometime go to either an 406 or 383 and i assume, while making an boat load of torque, an stock tpi system wouldnt allow the engine to wind up worth squat on that big of an cube engine so im stuck then either maknig a bunch of torque or doing an aftermarket platform.

An question though, could the 700r4's shift points be lowered to right when the engine stops pulling so their's no worry about needing your engine to rev higher? Also could someone pull up the adverage pricing for everything to convert to hsr because im getting mixed prices on summit.

 

cant afford it, but how much would something like this combo usually cost?

 

so basically as long as you have enough air going thru your intake? to compensate what air is able to go thru your heads or the other way around, your going to make power? Keeping TPI seems like it would be the best way for me being that i want alot of low end torque and it would keep prices down compared to buying an aftermaket intake or modding tpi

 

Basically as long as you can flow air into the motor you will make power the question is how much? I dont really like to talk in terms of horsepower because it can be really misleading and isnt really a useful except when talking about the peak/average hp. This is because horsepower defines what it could potentially do how much work the motor can do in a given period of time. Talking about power at an RPM is better discussed in terms of torque. This is because torque is torque it is a force that can directly be translated into what it will do in terms of acceleration where as hp only means what its capable of doing not necessarily what it will do unless you first convert it back to torque. Further more its gets even more misleading because of the way torque and hp are related. Gaining 10 hp at 1000 RPMs and 10 hp at 7000 RPM mean very different things in terms of torque gains despite being the same gain in HP. 10 HP in the low RPM will equate to a much larger increase in torque than in the high RPMs. This also mean that gaining 10 hp in the low RPM will make a big deal in terms of how powerfull the car feels where as in the high RPMs may not even be noticeable. So being that that is the case lets talk torque. The more torque you have the greater the acceleration will be for a given gear ratio. Torque will be related to your VE. As RPM increases your VE will start to drop due to the restrictions be it the heads the intake or whatever and your torque will drop in turn. The car will still be able to accelerate until the aerodynamic drag equals the force your motor puts out but it will feel like its falling on its face because the acceleration will be considerably less in the high end than it was in the lower RPMs though again it will still accelerate again till you hit your aerodynamic limits. So TPI is great for the low end and you can use a factory TPI intake but it will feel like its falling on its face in the higher RPMs. If you truly only care about low end torque this is not a big deal but make sure you truly understand what that means first.

 

My car shreds the tires, if I want it to. Personally the cost of replacing tires prematurely really doesn't sit well with me, so I don't break it loose very often. My point is a good matched combo will make good power, mine does, untuned, and I'm still running a LTR combo. Anyone can shred tires, just get a line-lock. If you want to get that power to the ground, you'll need suspension, not a 600hp engine.

 

sorry forgot about the thread, i went over what rolling thunder said but didnt comprahnd very well, still tired so i'll read it later.

im not looking to shred tires, which my car can already do, Im just looking for killer torque that passangers wont expect. Im not into highway racing but more into stoplight stuff. Im just looking for torque that will set you back in your seat when you want it to.

 

so.... can the 700r4's shift points be lowered to right when tpi starts running out of air so you have the benifit's of tpi being torque and you dont have the negative of running out of air early?

 

Not exactly. Although you are sort of right you do want to keep in mind TPI motors dont like steeper rear gearing like most car but shift points get a little complicated. You see where it will feel like its falling on its face is once the torque starts to drop off or even flat line. Now although logically you would think ok just shift at that RPM where torque starts to drop off but the problem is gearing multiplies torque and shifting into a higher gear multiplies your motors torque by a smaller factor. For example the 700r4s gearing is i believe something like roughly 3 to 1 for first gear and roughly 1.5 to 1 for second gear. That means first gear is multiplying your motors torque by twice as much as your second gear. So mathematically you can see that you would want to drag your gears out past your peak torque (the point where it starts to feel like its falling on its face) because even though the motors torque is starting to drop off the torque at the output of the transmission is still greater than if you shifted into second which would cause an even larger drop in torque. You would actually want to drag your gears past your peak torque out untill torque drops to a point where your torque at RPM A X 3 is equal to torque at RPM B X 1.5 where RPM A is your RPM in first gear and RPM B is your RPM you will be at when you shift into second. So as you can see its sort of a complicated mess but even if you shifted earlier to avoid that running out of breath region you would still actually accelerate even slower due to the fact your engines torque is multiplied by less in higher gears.

 

Ok i see what you mean, so theres no way to work around tpi's negative basically stock wise. how would alumi vette heads affect torque? Or would i just basically be just loosing weight? Im thinking i might want to just do H/C, exhuast, big tube runners (mine are dented), and ram air. This would create (if good cam is picked/heads ported slightly) an decent tire burner? Could i expect low-mid 14's with this package?

 

Well being that I dont know what heads you have on there now its hard to say what effect adding corvette l98 heads would be. Doing the heads, cam, exhaust with the addition of aftermarket runners all parts chosen appropriately would deffinetly have to potential to get you into the mid low 14s more likely in the 13s or possibly even better. The one thing I will say is note how i said potential as you have 2 conflicting goals. You want to do some good burn outs and you want to get decent 1/4 mile times. Running the 1/4 mile your going to want to get as much traction as you can possibly get because the launch with TPI motors is its strong point. This should be taken advantage of to its fullest extent because you will not really be able to make up for in the top end however having lots of traction will reduce your burnout ideally to none. On the flip side having regular street tires with no work to the suspension will give you outstanding burn outs but on the track you'll go no where. If you were willing to have a set of good rear tires for track days and a cheap regular set for everything else then ide say your goals would be reasonable. Otherwise trying to compromise on something in between good 1/4 mile times and burn outs its really hard to say what it will do as it will be more dependent on your driving ability than anything. Besides It might be cheaper to have a set of cheap day to day tires that you burn up and save a set good rear tires for track days.

 

thanks, i wanna say my heads or 837 or 827 but im probaly just thinking that, i looked an few weeks ago and it seems like its 1 of those two numbers. What would the price be for the h/c with mild porting on the heads? Reason i say the alumi heads compared to something else is because i would like the weight reduction and it would let me get some stuff done while i have no heads on the engine.

Well what i mostly want is something that will pull hard from an dead stop but i like the ability to smoke them with just the tap of the throttle so i'll probaly run, if i dont have an chance to get new tires for daily use, my current old but like new tire for doing smoke shows and i'll get some good fat slicks for the strip.

What all suspension parts are we talking about to get all the power to the ground? i'll be replacing, with decent peformance shocks/struts and springs plus an front end rebuild kit but im guessing were more talking about sways bars and stuff like that right?

I mostly want to on the street be able to light up the tires quick and make an total smoke show to scare any opponent off. The car alreadys smokes the tires quick so with some good low end mods the tires will really light up.

 

As far as prices go it can be as much or as little as you could imagine. Depending on what parts you get and where you get them whos doing the porting work this could be really expensive or fairly cheap. For example you could probably find a set of aluminum vette heads fairly cheap do the port work yourself and toss in a budget cam that will install with no issues. Or you could go crazy convert to a roller cam (im assuming its not a roller block) send your aluminum vette heads in for some serious machine work and spend ungodly amounts of money. So pick a budget and we can discuss how much youll have to compromise to be in that budget. Reasonably speaking if you want aluminum heads i would save yourself the hassle and go with aftermarket heads. The problem with stock heads are they have clearance issues once you start to get to the high lift cams which youll want most if not all heads have pressed in studs that will pull out when using stiff valve springs ect. Also keep in mind if you get used heads it would be a good idea to have them rebuilt.

As far as suspension parts are concerned yea theres a bit more too it than just shocks. Next time your under the car take a look at all the components that make up your rear suspension. Youll notice pretty quickly that the stamped steel parts are pretty flimsy and not really up for the task. Even the torque arm which seems that it would be pretty solid will make a noticeable difference going to an aftermarket piece.

If you mostly want to do smoke shows than building the TPI system will accomplish that. TPI systems have been known to generate big block torque out of small block chevys and it does so in the low RPMs. The problem will be how do you take a car that wants to do break loose at every tap of the throttle and make it quick because again if theres not enough traction and you will go no where. Its like imagine driving your current car in the rain or snow you can peel out all day long but its hard to actually accelerate fast because you cant hook up. You can experiment with this as like I said with that much torque in a car thats not really built up to have maximum traction it will truly be a matter of your driving ability. Doing the suspension work and getting wider wheels and installing cheap or decent hard tires next time you need to buy tires should make it reasonable to drive while still being able to do outstanding burnouts.

 

my problem is i really cant just pick an budget being i cant do any of this for an bit anyhow, i think i mostly just want to get the vette heads, do an slight porting to clean them up, and then put on decent grade parts onto the heads. I dont want to make this project super expensive and i just want an good boost in peformance and i would imagine alumi vette heads with mild clean up could do that pretty effectively.

Sorry, im not much experienced with suspension/chassis and again, i dont really want to be spending an boat load of money to replace everything.

My problem with the tire idea is i live in oregon which is known for rain nearly all yr and i plan of DD the car so i just dont want some super cheap tires that would increase my chances of getting in an wreck in any weather, i love doing burnouts but i think i can keep myself from ruining good tires, maybe i'll just get some good all weather tires and then get an super cheap rear pair for an staged burnout.

 

those vette heads would do more harm then good on that 305

as far as heads for that motor....i just have some port work done on the ones you have...if you want to put money into the 305

besides you should take it slow man this is your first car and you dont have your license yet ...id just drive it as is ...youll love it ....and the sound of the v8 scares off high school kids

 

BTW didnt the 87 have an lb9 with 416's....those are great heads!

 

how would they do more harm then good? lower compression? I just want some cheaper priced, necent flowing alumi heads, is there anything car i could pick the heads off that will be good, i really want aluminium heads.

I know, but an little extra power would hurt, im not trying to run 12's, i just want an decent boost in peformance.

and it seems like my heads are 837's? but im probaly wrong.

 

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