I <3 the TPI motor!!!!!!


Outdated, yes...

Cool factor of 10!!!!

 

It sounds AWESOME at full tilt.... Like an erotic quartet of tuned explosions inside a cube of iron.

True Story!

 

Having run a CCC Q-jet on an L69 and TPI on the same engine in the same car, I preferred the powerband & fun of the Q-jet with a stick. The TPI is entirely tractable and torquey, but it gives up speed and overall powerband. And with a stock cam, the Q-jet pulled 25mpg going well over 70mph, so that wasn't a gain when going TPI.

 

Dude they sh*t talk everything that isn't an LS1. And in ten years they'll add the LS1 to the list.

 

TPI's problem (and strength) is the "T"; "tuning".

Think of a musical instrument; a flute, guitar string, etc. You pluck it, or blow it, and it makes a particular pitch. Doesn't too much matter how hard you pluck or blow it, you still get pretty much the same pitch. If you don't believe me, go play a beer bottle. If you're a flute player, you shouldn't have any problem getting it to play a 12-oz note. It'll play roughly the concert G right below middle C at roughly 200 Hz. The frequency is determined by the dimensions of the vibrating column of air. Got the picture?

That's what TPI is. A musical instrument: "tuned" acoustically.

It works by way of the intake charge rushing down that ginormous long runner while a cyl is getting its gulp of air; at the end of this intake "event", the valve closes; meanwhile all this stuff is still barreling down the runner. It slams into the back of the just-now-closed intake valve. This produces a pulse of POSITIVE pressure. The pulse travels BACK UP the runner, bounces around in the plenum a little bit maybe, and part of it finds its way down into the NEXT runner that's filling a cyl, AUGMENTING the cyl fill... which is to say, PACKING that next cyl a little bit more full than it could fill itself on its own.

This pulse, a compression/rarefaction wave in air, travels at ... the speed of SOUND, because, THAT'S WHAT IT IS; in essence, it's a SOUND.

The speed of sound is a little less than 1100 feet per second at room temperature and pressure; a little slower in air at lower pressure, a little faster at higher temperature. Let's round that number off just to make it easy to handle, let's call it 1000 feet per second. That's one foot per millisecond. Got that number FIRMLY in your head? Don't let it fall out .... one foot per millisecond.

So. This pulse is generated by the whole intake valve thing; it travels BACK UP the runner, which is about 22" long, to the plenum; rattles around in the plenum a bit maybe, or maybe not, maybe it just directly finds the next cyl. Let's give it the benefit of the doubt and say it doesn't waste any time, but it takes 4" from the top (plenum) end of one runner, to the end of the NEXT ONE IN THE FIRING ORDER. OK fine, now the pulse from say #1, pressurizes the #8 runner a bit, and aids cylinder fill. But.... BUT... that runner is 22" long TOO. So now we're up to 22", + 4", + 22" MORE that the pulse has to travel from one cyl to the next, means 4' from one intake valve to the next.

4'. Got it?

At one foot per millisecond, 4' = 4 milliseconds. That's 1/250 of a second. That means TPI's reinforcement effect PEAKS at ONE FIRING every 4 milliseconds, or, 250 firings per second. Got it?

OK fine. 4 cyls fire per revolution of the crank. That means, there's ¼ as many revolutions per second, as there are firing events. That means, if a cyl fires every 4 milliseconds AT PEAK TUNING, then the crank turns once every 16 milliseconds. Got it? 4 x 4 = 16.

If you'll allow the liberty of another roundoff, just to keep the numbers SUPER EEEEEEEZY to handle, let's call that 240 firing events per second; which works out to exactly 60 crank revolutions per second. Got it? Are we OK with that so far? Any questions? Have I made any mistakes ANYWHERE?

OK fine: there's 60 seconds in most minutes. (some have more like when you're waiting for something TERRIFIC to happen, some have less like when you're already having a REALLY good time, but by and large, most minutes have right about 60 seconds in them) Got it? We're all still good here?

60 x 60 = 3600. 60 per second = 3600 per minute.

That's the RPM TPI works at. 3600 RPM. A good RPM for the street; if you're at a traffic light and you kinda stomp on the gas, like, as if there was a cockroach under it, that's about the RPM where the engine kinda starts to "sing" and you expect things to be happening. Right? So far so good. Advantage: TPI.

Problem is, that pulse is SOUND. Just plain, common, ordinary, garden-variety, everyday, SOUND. And as such, there's a NEGATIVE pulse right behind the POSITIVE one, as the air rushes the other way to try to equalize itself. So what do you suppose a NEGATIVE pulse is going to do when it finds itself in the plenum there, affecting THE NEXT cyl in the firing order?

You guessed it: instead of CONstructively interfering with the next cyl's fill and ADDING to it and producing MORE power, it's going to DEstructively interfere, thereby SUBTRACTING from that cyl's fill and making it produce LESS power.

This NEGATIVE effect is MAXIMIZED at 5400 RPM (1.5 times the CONstructive interference RPM), right about where HP begins to need to be made if you're going to win a race.

In other words, you SACRIFICED anything resembling "power", in favor of this huge seat-of-the-pants blast at 3600 RPM. Which is kinda cool from traffic light to traffic light in the suburbs, but isn't worth CRAP trying to pass a semi on the freeway, or at the track. You get this "Mount Everest" rush of toque (that's what it looks like on a dyno graph), but the torque falls off afterwards like a cliff. And since HP = torque x RPM x a constant, then if torque falls off as RPM increases, you don't get HP.

Notice that we didn't talk about head flow; plenum size; throttle body diameter; "chips"; or ANYTHING ELSE. THE INTAKE DESIGN, and its TUNING, dictates this behavior. As long as those 22" runners are on top of that motor, THIS IS WHAT IT'S GOING TO DO.

In a nutshell, that's why TPI SUCKS. It's a masterful design for what it does, but that's IT. It inherently defeats anything and everything beyond that. There is no upgrade path. What it came with is what you get.

Any questions? Anything I didn't explain fully enough? Anything I should repeat in a different way to make it clearer? Let me know and I'll do what I can to help you understand.

 

LS1, yes. "LS" series...I'm gonna disagree.

I was a doubter once too, but once you experience the "LS" series, there's not much going back. (Unless of course the new LT1 is absolutely amazing, then count me in for the LT series!)

 

the TPI design was full of compromises, and in the end you wound up with a 350" engine that could only hope to run even with a Mustang that had a 302" engine...
yeah, the TPI 350 would do better burnouts, and felt snappier, but the 5.0 Mustangs could keep up with them.
everything that has come after the TPI- LT1, LS1, etc- has been an improvement in every way.

 

Typical hot rod stuff, headers, better exhaust, better cam, and optimizing the tpi set up (port match the intake, flow the plenum etc per article in tech section) are the bang for buck bolt-ons. Then you start getting into headwork (porting, bigger valves or diff heads etc.) It's really best to figure out your end goal and develop a plan to get there. If you really want to spend any kind of real money on performance, better to start with a newer/better motor.

 

Sofa, I agree with most everything you just wrote on its general theory in how TPI acts.

But I also gotta say this, if GM had actually built the TPI system with a 350ci motor in mind and shoved say a big mouth base, larger ID runners matched the plenum for that TPI would have been making more power up than in what we know as stock trim. Look at the effects of the First TPI intake. The massive runners feed larger cube / higher revving' engines easier.

I agree that TPI's downfall compared to other stock induction systems GM used is its highly specialized nature and the expense of upgrading it. But it can be made to work well in different form (such as the First Intake.)

 

Im talking about engines with TPI's on them. Im never going to say a 305 is better than a 350, just saying to the other guy that the difference between L98 and LB9 is very small when both got the same cam. The reason that 305 was so pathetic was because it got the gas mileage cam.

FIRST intake is awesome, sure, but I will still avoid any long-tuned runner system like the plague thanks. It doesn't go NEARLY far enough IMO.

The LS1 intake uses some sort of tuned runner length system too, I think, but it's much better executed. Not sure if the FAST systems replicate this or get rid of it altogether, as I dont look into that stuff much. Way outside of my cost window and too far in the future right now. The only TPI I would run is 1989GTATransAms super behemoth TPI. THAT is how it's done.

 

You seriously never cease to amaze me

 

So how can i get hp out of my tpi


Seriously excellent response that should be a cut and paste link on EVERY stinking thread like that.

ya only get so much on avg by messing with these yet everyone that wants to build one is hoping they willmagically get 50hp more. Argh...


Insanity=doing the same thing and expecting different results.



The wheel was invented already

 

@ this entire thread...

 

Are you talking about the TTA? Its a GN motored thirdgen. What the heck is a Super Behemoth TPI?

 

Can you take a stab at explaining the meaning of life now?
Lol.

 

He has given us the gospel of Acoustics.
Good translation. Still, I like to hear it from Matthew, Mark, and John.

 

As a professional tuba player I have an issue with the concept that pitch is not affected by the intensity of the attack, other elements have to be compensated to keep pitch centered.

But if it works for the illustration, roll with it.

 

^I was thinking a better analogy might have been lungs, for volumetric efficiency, but it was a great post. He basically summed up a multi-part article in GMHTP into one easy to read post.

 

91 firehawk at 350 hp was sorta tpi behemoth

 

If you want to make a TPI car go fast in the quarter, do a full exhaust system with 1 3/4in headers, 3in cat back and open up the air intake. You will be in the mid to low 13's depending on the year of the car. The speed will be 101-105mph. DO NOT OVER GEAR THE CAR. 3.73 is an overkill because you will be going through the traps at 5300. The power cut off is 4800. 3.42 would be the best gear for the L98 automatic. The stock 3.23's will work also. When my car was stock except for the exhaust, I stayed side by side with a LS1 auto Camaro with exhaust from 50-110mph because I was still in the power band with 3.23 gears.

 

SOOOOOO TRUE!!!

 

Your 100% right. Lt1 owners touted it over the l98, then lsx owners tout them over everything chevy ever made. Youd think the l98s were horse drawn carriges the way some of these guys talk about them. Lol.

 

Stock lsx vs stock l98 yes big difference. Modded l98 (any efi variety for our years,second gen block) vs modded lsx same cubes not so much.

 

I think the TPI is a great piece of history and I'm happy that some are preserving that.
Just like the John Deere 2 cyl tractors. You don't see em winning pulling contests, but they ARE cool to see.

Seriously, take them for what they are, not race motors, and they're fun in a car for just tooling around and staying out of trouble Good show car motors.

 

True dat...

However bad a stock LS1 will humiliate a stock L98, it does nothing but get even more humilitating as the 2 engines are modded. The LS1 RESPONDS to mods, whereas the L98 (unless you're on one or 2 certain specific "friendly" SoCal chassis dynos whose #s don't always agree with track times) DOESN'T. The L98 in fact might even GO SLOWER from modding, as people who have jammed the LT4 HOT cam into one can tell you. (if they're honest and not suffering from cognitive dissonance http://en.wikipedia.org/wiki/Cognitive_dissonance or effort justification http://en.wikipedia.org/wiki/Effort_justification)

 

Us SoCal people have a hard time trying to go to a track when all the tracks are close down. Yes we love the dyno too but from what we been doing we can see the difference in performance with the mods we have made. It a feedback to tell you guys what works and what doesn't. It the only way we could tune our cars without getting a speeding ticket. Hopely this new found problem of tuning is solved with the manual cars. We may have been doing something wrong because the manual cars are not making power past 5600. But we are getting it together.

The TPI's can make some good power and good e.t's with lots of torque and mid range power.just gear the car for torque and mid range, not for above 6000rpm. Like I said before 3.73 are not for a stock or even mild modded L98. You will not stay in front of a LSX car. But you can with the stock gears and lots of torque and midrange power.

 

Yeah I know; I lived within earshot of the Carlsbad track (at the very top of the hill overlooking Shadowridge golf course from the south... you could see the back side of the house a couple of doors down the street from Melrose at the track entrance) right before it got turned into an office park. That's a tough part of the world to be a car enthusiast these days.

 

Vincent what are the track time? That should be an 11 sec car even at stock weight. So your pushing over 440hp at the crank on 360 cubes? thats pretty impressive for a tpi. Motor specs please.

 

I don't have any track times with the Miniram. The engine had a knock so I pull the engine and put the stock engine back in. It has gone in the low 13's on the stock motor.

 

Oh I thought it was a tpi or super ram motor. What cam with that miniram setup?

 

It was a Super Ram. Check the sig!

 

See a problem?
CFI intake ports top pic; reg SBC intake ( inc TPI ) underneath

 

Nice you have the same setup I do except I have SW long tubes, and lpe 219 cam and its an auto. I also have Holley HP ecu. Should be interesting if I ever get to dyno it.

 

No.

This is what Im talking about:

https://www.thirdgen.org/forums/tpi/...-runner-1.html





Its probably about as close to an "ideal" tuned runner system as you can get.

 

Way to much work when you can buy a first out of the box to do the same and use bigger heads. I read the whole thread and couldnt find one comparison to the first intake he had before on it. ?? Check out this thread

https://www.thirdgen.org/forums/alte...n-runners.html

That behemoth tpi is a good one off that is commendable, but practicle, unlikly. If you want to be stealthy I guess, but who worries about that anymore? Those CA guys sometimes, idk.

 

Probably because the first is barely an improvement over stock? I dont see any 500hp FIRST injected cars anywhere.

https://www.thirdgen.org/forums/post...9-post110.html

The TPI is a heavily modded one, but as you can see the HSR has far more potential because it isnt a tuned runner system and it doesnt cripple itself at higher RPMs. The HSR had a higher mph here too so its obvious it made more horsepower. The system above had, if I remember right, 2 inch diameter runners. MASSIVE airflow potential, way bigger than the tiny 1.75 inch FIRST runners.

 

That tpi isnt that heavily modded, 419 rwhp isnt 500hp. And thats a notorious CA dyno as some have pointed out here. The threads I posted have before and after times. This one doesnt. And nothing since. Not knocking the work he did, but I feel after using the first he felt he could do better than it modding stock type components. Ive seen super ram combos put down those kind of numbers with just port matching. Thats a one off you will never see production of. Hats off to the one who did it, but there are roads much easily traveled than that. I would understand if there was no aftermarket for this motor, like someone said before, why try to reinvent the wheel.

 

That TPI was using SLP siamesed runners that arent even available anymore. You'd be hard pressed to match that with currently available parts.

Im not a fan of TPI by any means, but I still think it has its place. I give my car a 50/50 shot of having TPI on it within the next two years. Or at least a factory TPI computer running a stealth ram or a FIRST intake. Tuned runners are always going to be a handicap in the higher RPM ranges, but at the end of the day if you can just make it work well enough to get to 6000 RPMs, through siamesing and larger tubes, some good heads and a roller cam could theoretically hit 450+ hp with it. But I've just never seen a long tube runner spin to 5500, much less 6000, except for 1989tramsamGTA's setup above, which was extensively modded for a specific runner tuning through length and diameter and a much larger plenum.

And apparently teh FIRST setup has a terrible throttle body:

https://www.thirdgen.org/forums/tpi/...onversion.html

 

Headers can help you some! Do not waste your money throwing a cam in the 305. I had a 305 tpi in my car originally and i put headers on it, bbk throttle body, completely ported intake system top to bottom. Just remeber with a 305 and 58cc heads they dont flow much. I really enjoyed mine and it was fast but i had the t-5 behind it also with 4.10 gears

 

I've seen his hp peeked at 6600 with the SLP runners but they were heavily modded and modded to work with the FIRST intake manifold. 420whp@6600

 

Interesting read sofa

 

The 419 # was from the motor you posted pics of. If you are looking for a HSR I have one for sale right now in the for sale section complete. Im wanting to go with a First because the application calls for it. Althought I love my super ram I thinks its the best of both worlds. But its such a pita to assemble. Hsr and miniram win there. Ive done them all and Super ram takes the cake. If I could get my hands on one at a decent price for my tahoe I would. But im shooting for at least 500ftlbs at the crank for around town driving. The first will get me in thay range maybe more accoring to ken at first. Its already put down 480 with a single plane.

3.23 or even a 3.08 would make a great street puller with a modded tpi or first. Im just not a fan of spinning my motors to the moon because rpms like to eat parts and a motor has to be built accordingly for it. On a budget you can build a good street strip witha tpi based intake and shift it under 6. With decent quality parts. I wouldnt spin a cast crank motor to 6500 making 425+. Your just asking for trouble. Why do you think tpi based motors are still so popular for the cruise scene? You can buy a zz based block and use tpi based components and have a stoplight terror. Great for the guy who doesnt visit the strip.

 

Finally someone is speaking my language. 3.73's is way too much for a mild TPI. 3.42 is the limit.

 

I beg to differ. I'm very happy with my 3,73. I have a very mild tpi motor with factory cam and heads and love my setup.

 

I can agree! I had 4.10s with a stock tpi 305 and loved it!

 

True dat...

The reason people dog the TPI engine is because it's compared to present day technology(LSx, Ford modular motors, hemi's, and turbo 4 cyl's). Definitely a fun engine for its time and price range.

 

wasnt too many cars that fast in that day! Good car in that era

 

I know how they feel with the stock motor behind a T5 but the E.T.'s are the same.

 

Here is an old bookmark I came across in terms of flow numbers different manifold. Thanks to the vette forum member vader:


First link to some super ram info and such:

http://temp.corvetteforum.net/c4/vader86/superram.html


Second link to flow info on various manifolds:

http://temp.corvetteforum.net/c4/vader86/flow.html

Enjoy!

 

Had to add this link, alot of good info and dyno stuff too, enjoy!

http://temp.corvetteforum.net/c4/vader86/


Search the performance link left side....