Todd91SS

Hey guys. This has been about 4 months in the making more or less. It is mainly the complation of my personal experince, but is also combined with others' as well in the FI performance community.


This is the best way that I could come up with to try and explain to the TPI and FI community in general how to make power and also why so many cars do not. Especially modified TPI cars.

I honestly hope that this helps many of you out there. That is the purpose. There is a word file and an adobe file. The adobe file is much smaller, but if you get errors, then the graphics most likely won't come up, and then try the word file.

Happy reading and I hope this file finds its way to your hard drives for future reference!

http://fox.vet.purdue.edu/media/TPI.pdf

http://fox.vet.purdue.edu/media/TPI.doc

breathment

hey, thats pretty awsome, good job.

------------------
- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16

89 Iroc Z

Very Very Nice!

------------------
1989 Iroc-Z 5.7 350, Blue, T-Tops

Lightly Moded:
Edelbrock Headers, Rebuilt B&M 700R-4 Tranny, Higher Stall Torque Converter, Airfoil, 3.4 w\posi, K&N's, Ported & Polished Plenum
-- Blue LED Bakelite Dash & Climate Control
- I am just some 17 Year old spending every dollar I make on my car.

88IROCs

What a load of CR@P!!!

With all the good info on TPI(and other intake methods) to be found at 'thirdgen.org', why would anyone attempt to pass off trash like this?

Tom Simpson

I was getting depressed there until the end.....phew.....thank you vortech

Todd91SS

88Iroc, I'll have to apologize to you. I have learned that it's very difficult to teach people who already know everything. But thanks for your well thought out fact based response.


This is written for the people who actually want to think about what they're doing to their cars instead of just listen to what TPiS or RKSport tells them to use.

You know, it's replies like yours that keep the older members off this board nowadays.

88IROCs

Gathering information from outside sources is by far the easiest method to building knowledge. However, gathered information has no usefullness if you don't undertand the information or how it can be utilized. If you can't comprehend the gathered information and don't make an effort to comprehend it, the exercise becomes nothing more than collecting trivia. Compounding the mistake by repeating information you do not understand, will not enlighten your audience. Rather it will lead to confusion and showcase your own lack of understanding.

Todd, you repeatedly try to simplify your subject, or describes the details as meaningless, in attempt to cover-up your lack of understanding. You enlarge the scope of your error by constantly straying from the core subject; trying to draw correlations from themes that have no relation to that core subject. All the while, impressing us not with the depth of your understanding of one tricky subject but rather conveying that you know litle or nothing about many things.

Simplifying can be a good device to quickly make a point, without explaining a lot of details. However, it's success is predicated upon two assumptions:
a. the author knows his subject matter and could explain the details if clarification is needed.
b. the reader can see a logical progression in the author's argument, without getting confused(or irritated) by the omitted details.

Sadly neither is true in this article. Hopefully, Todd will realize that he has wasted his allotted 15 seconds of fame, and will turn his attention back to his collection of oversized Lego's.

Originally posted by Todd91SS:
88Iroc, I'll have to apologize to you. I have learned that it's very difficult to teach people who already know everything. But thanks for your well thought out fact based response.
I'd be the first to tell you there are aspects of TPI I don't fully understand. That's why I wouldn't author an article with the presumptious title "Making Power With GM Tuned Port Injection". Further if I was to make a statement such as "This guide will serve as an investigation into the world of tuned port injection", I'd back it up by doing some actual investigation rather than repeating rumours I'd heard at the local hamburger stand. You want a fact-based response? I'll be happy to send you one that explains the error of almost every statement you made in your article. I read that entire article, and was left in awe of the amount of misinformation you possess.

This is written for the people who actually want to think about what they're doing to their cars instead of just listen to what TPiS or RKSport tells them to use.
Too bad it wasn't written by someone who could think about what he is doing, before he does it! Too bad it wasn't written by someone who could think for himself in an attempt to seperate fact from fiction. Too bad it wasn't written by someone who could see the limited knowledge he possesses, before he tried to confuse others with his fantasy!

You know, it's replies like yours that keep the older members off this board nowadays.
What an absolutely lame excuse for a rebuke. Do you have the name of any "older members" that are kept off of this board? Or is this another attempt to pass your ill-informed opinion off as the truth?

Or do older members respond less to a question because it has been asked and answered 100 times before. Or maybe they respond less because there's a know-nothing expert, like you, repeating some blarney that's been tried(and failed)100 times before.

Btw, does the fact that I originally joined this board in June '98(under a different username) qualifiy me as an older member. Or is this honour only based on the number of posts a member has made? Do you consider yourself an older member, and if not, why did you try to use this trite device to belittle me?


For the record, I have yet to contact anyone at TPiS(I have read their first book though) or RKSport(whom I didn't know was a supplier of parts for thirdgens). However, if I did have that contact, I'd extend the same courtesy as I used when I read your article: I'd approach with an open mind. If there was something I didn't understand, I'd seek clarification from the source or from one of the many knowledgeable "older members" at thirdgen.org. But you can be damned sure I wouldn't blindly repeat something about which I didn't have the barest clue.

Honestly, your entire response shows how much contempt you have for making an effort to convey something meaningfull. A 14 year old could compose a more cohesive and factual article in four hours, compared to the one you claimed to have spent four months investigating and producing.

crucial

So esentially you're telling us WE NEED a Miniram to make any power and hang with LS1s and LT1s. Well I disagree.

I can smoke a stock LS1/LT1 fbody anytime I want to with my TPI. I even went up a few modified LS1s and I can still eat them alive. TPI has GREAT potential if you choose your parts carefully.

------------------
1992 Z28 5.7 TPI

ZZ4 longblock
Harland Sharp roller rockers
Accel base and SLP siamesed runners,
52MM SLP Throttle Body
Hooker Headers & Flowmaster catback
MSD6A ignition
aluminum driveshaft
World Class 5-speed

86Tra/maro

The MAIN POINT is to buy matched parts, meaning. If your buying Upper RPM cams, cylinder heads, ETC. You really need a short runner intake to take advantage of the rpms of your new setup! If you ever noticed, the torque type carb intake manifolds always seems to start on either the left or right side of the intake & feeds the opposite head. That creates more runner length causing more velocity,making more torque example (Edel's Performer intake)
Most high RPM motors usually have some type of Victor Jr. short runner intake manifold. With this in mind, doesnt it make sense that short vs. long runners would apply to TPI the way that it applies to carbs?
I'll bet that if u had 2 identical 383 long blocks with AFR heads & a decent 224 or better cam with at least 525 lift on a 112 :
1. With a big mouth intake , TPis's runners and ecm programming.
2. Performer Rpm Intake, 650 Holley carb Dist. recurved
I think that the carb would win because of the better breathing shorter runner design. Mini Ram is the way to go If u want to increase your horsepower!


------------------
86 Tramaro 90% Trans Am/ 10% IROC/Z (nose, hood,& fenders)
Trans Am Mods as of 1/10/01
3inch
T.E.S/Flowmaster setup,gutted cat,gutted maf,relocated mat,373 gears,upgraded factory chip,255 lph walpro f/pump & throttle body coolant bypass
njdaewoo@excite.com
New mods as of 6/10/01:
383sb engine
Comp Cam Xteme XR264hr-12
smog pump by-pass

88IROCs

86Tra/maro,

I'd definitely agree with you that buying matched parts -meaning those that work towards a common goal- is very important. But buying into old myth's -such as: the stock TPI intake cannot make power above 4500 rpm- without investigating the source does not improve the knowledge base. I have seen numerous examples where the stock intake components yielded hp peaks above 4800 rpm, all the while increasing torque at all rpm points below.

Here is the results of one of a number of recent article supporting my claim(you'll note that Todd didn't cite even one verifiable example to support his claims):



The engine was a rebuilt 305, with aftermarket cam and exhaust, a stock tpi intake and stock heads treated to a multi-angle valve job(stock hp and torque curves). The heads were then swapped for World Products "305 Torquer" units. This test, and others like it, prove the TPI intake is not as rpm limited as the naysayers would have you believe. Nor does extending the peak hp value necessarily cause a decrease in lower rpm torque. On a 305, the heads are so restrictive that they limit power throughout the rpm range. Unfortunately, some folks blame the wrong components(the intake in this case) for the limited powerband, and then wonder why replacing them does not yield the expected result.

Keep in mind though that: the OEM TPI intake was designed for a 305. Using it on a 350 makes it an undersized cludge, and you couldn't really expect the same results. Unless you bought long runners that had the volume to support the increased displacement.

This is just one example of the kind of false claims Todd makes throughout his article, without showing any supporting data or investigations of his own to verify his claims. In essence, he heard it from a friend, who heard it from a friend, who heard it from a friend,..... Unfortunately, by the time the information makes it's way to Todd, it has been completely distorted. Then his own complete lack of understanding distorts it some more.

The pity is he could of consulted with people here for clarification and understanding. That appears to be too much effort for someone who seems content to parrot opinions which he doesn't comprehend.

Todd91SS

88Iroc, you have completely succeded in missing the entire point and direction of this document. This is not intended to be an in-depth document that requires a PHD to get any benefit out of. If you would like, you can feel free to email me or drop by Mich. sometime and we can talk about the details of engine building theory all you want, as well as my qualifications and where this information comes from. That's no problem. I have all the facts (an especially real world experience) that you could possibly wish for.

The idea here was to present factual information in an easy to read format for newer people just getting into it.

This is what works. You are free to go on whatever path you wish to take, but you will eventually come to the same conclusions based on experience.

You posting one dyno sheet from one engine is more meaningless than you can imagine. I could post five hundred dyno sheets claiming to show whatever vague fact I was trying to prove at any given day.

You're absolutely right about simplifying my subject. Because it is simple. That's the point. This is the summary of all the numbers and data and testing. Written in a form that everybody can understand. If I would have gone more in-depth, half of the readers would have gotten no useful information out of it. Isn't it long enough already?

I absolutely love people like you who try to label others as trying to cover up our lack of understanding without having one single bit of background on us or the real situation. How in the hell do you profess to know my level of understanding?

You would do the world much more of a service by either putting all your obvious superior knowledge to paper and helping others in acheive their goals or stay in your corner and don't get in the way of others trying to.

I am not going for my 15 seconds of fame and anyone who would accuse me of that is showing their lack of intelligence. I am not trying to convince anyone of my qualifications, nor do I want to have to.

Quote: Honestly, your entire response shows how much contempt you have for making an effort to convey something meaningfull.

You're right. I have no desire to make a meaningful point. I have a great deal of contempt for all of this. That's why I spent time on it.

How in the world did you read in that document that I wanted to argue about anything? I was simply making available the information that I have found works. And I assure you, it does work. I have no time or effort to argue with you guys. I just wanted to make it available to the new people with open ears and minds.

And honestly, the only people who would get offensive to this document are those who have put much money and effort into aftermarket TPI components and have not reached the indended power levels.

And I am surprised by the amount of time and effort you would spend to try and discredit this when I was simply trying to help.

One last comment. If you knew me personally, or knew my background, or knew the kind people at GM who helped with this information, you may not be so quick with your misguided negative comments.

In kindergarten, I remember something about if you can't say something nice.........

Ed Maher

I have to agree that this document is basically crap. I don't have the time, or the desire, to tear into every error, but any article that discounts the effects of turbulence in the plenum, and also says that a 48mm TB must be enough for us since a crate 502 can make so much power through one is obviously completely lacking any real understanding of basic physics, let alone the ability to look at the system as a whole.

In other words, while i am sure this was not geared for people with any level of understanding about their cars, i could not even recomend this as good reading for a complete newbie. It is simply too flawed to be of any value IMHO.

------------------
Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.7 @ 93.6
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

Todd91SS

I never claimed that the information wasn't contraversial. I know that much of it goes against the "commonly accepted" view of TPI power.

So why is it that TPI cars are so underpowered? Can't you guys open your minds up to the possibility that the commonly accepted methods are wrong?

This was supposed to get you thinking. I guess it has. But I will also say that none of this is new information. In fact, most of it is a compilation of widely known facts. And the effects of physics? I believe that I have a pretty decent grasp on physics.

Ed, have you really sat down and thought about the process of the intake system and what the components truly do? You should. Forget what you've read and think about it. Why did they use what they did?

To say the information is crap IMO is poorly placed. Once again, I'd love the chance to sit down with everybody and talk face to face but I doubt that's going to happen. This was my best attempt at providing what works to truly be happy with your cars.

This information can't be helpful if you're not willing to think about your motor in a new light, different from what you've come to believe in the past.

What possible reason would I have to take all the time to write that only to provide false information to strangers? What would that gain me? I have been through every aftermarket combination possible and I feel that I honestly can help people out there. If they are willing to listen that is.

Ed, hopefully we can discuss it sometime. I'd like to.

Ed Maher

Look, i don't have the time to go into detail about why your information is so poor. If i did, i would be writing an article of my own.

I mean, cmoin, you discount plenty of theory that does work in practice (and has physics behind it), and make completely unbelievebale claims, with no physics behind them, that DO NOT work in practice.

For example, you discount porting a stock base, and/or anything that enlarges the runner diamter. Your argument is that increasing diamter kills velocity, which kills torque and the whole point of the TPI intake. While this is a collection of theories that would seem to make sense (if you had a hole in your head and no grasp of the concept of 'system') This completely ignores that TPI makes it's low-end torque through the INERTIAL effects of long runners, coupled w/ RESONANCE effects through the long runners. Yes, inertia is affected by velocity, and yes velocity will decreain a larger orifice given the same volume, but to make torque you still need to move air and create cylinder pressure, and to move more air you need a bigger runner.

Look, it was an admirable gesture for you to try to put together a basic guide to making TPI fast. However to do so is actually a very large and complicated topic, well outside the scope of a 10 page word document. In trying to abbreviate the subject you've only served to confuse things worse.
In closing, LTR TPI cars have run well into the 12s. Obviously the intake can make some power. The question you seem to be trying to address 'So why is it that TPI cars are so underpowered?' is better answered as follows... cuz people don't bother doing their homework, or tuning, and they expect they can throw some money at it and it will go faster. Your document is another example of someone who just isn't doing their homework (yeah, the secret to making a TPI fast is leaving the turbulence in the plenum and run a small TB, right :rolleyes

I'm sorry if i'm coming off short, but like i said, i don't have the time for this right now. In fact this will prolly be the only post i respond in all day, but after reading your article, i felt it was so misguided that i had to offer my 0.02 before anyone took it seriously.

Todd91SS

I never pretended to say that understanding the design and principles of the systems was simple or could be done in 10 pages! Of course there is more that's involved. The utter numbers of calculations that go into figuring runner diameter alone would be astounding.

So you don't like my TB thoughts. That's fine. I feel that they're founded, but to say there is no usable information there is pretty short-sided. I think that anybody who has worked around FI systems long enough would agree with most of the information.

And what is the point of writing an article like this if it just restates what everybody else already knows? Wouldn't it be much more helpful if it explained what's flawed with what everybody already knows?

And I'm not seeing a whole lot of OTHER TPI solutions manuals floating around out there. Instead of discounting it, how about contributing to it to create the "perfect" document?

85transamtpi

I have to agree that the article presents a lot of information that is questionable at best. I would rename the article "My thoughts on tpi" by todd91ss and view it as opinion only. Im not trying to start an argument but you did say a lot without backing anything up. Todd91ss, I would say you may want to sit down and rethink some of your theories. Basic physics and common knowledge should point you in the right direction.

*VIEWER DISCRETION ADVISED*

Ed Maher

The whole purpose to this board/site is to build the perfect resource to understand and modify thirdgens to be the best they can be. And at that purpose it is performing admirably. If you go back just a few years ago, the concept of PROM burning was black magic, only a handful of people had build strong running NA TPI cars, etc. t makes me shudder to think of some of the things we used to believe and practice commonly.

I only posted to add negatives about your article because it contains blatant inaccuracies. Just because the RJ 502 makes whatever power it does with a 48mm TB does not mean even 13 second TPI cars have seen consistent repeatable gains with a bigger TB. Just because air doesn't flow in a perfectly straight path in the plenum does not mean that reducing turbulence won't have any effect, especially when even stock TPI cars have seen gains from porting the plenum.

There are just too many paths to take when it comes to modding a thirdgen to write a comprehensive document. Depending on your goals there are many ways to make a TPI car respectably fast on different budgets and with different end results. Don't you think all the books on TPI and injection over the years have tried to touch on these topics, and yet they still all fall short and contain flaws (TPIS insider hints, lol, bwahahaha, roflmao, bwahaha, etc)

If you want to truly add something to the body of knowledge here, the best you can really do is learn and document your own experience. After i get a little further with my vert i plan on making a new tech article on basic mods for TPI cars to update the old version we have here. It will be limited in scope to basic mods, and i will hopefully try to explain thge things that should go into the decision process when you get into modding. This way the reader comes out with a better picture of what to start with and where you can go from there, and then decide the best way to get what they want.
I wish i could tell you how to make your paper better, but i just can't. From the outset you make weird generalizations, and write TPI off as useless. Why doesn't TPI perform like an LT1? Well thats obvious, but then you go on to say that adding better flowing aluminum heads and more compression that an L98 won't run in LT1 territory. That is just not true. How can you write a paper about making TPI perform when you're raising the white flag from jump street?

88IROCs

Ed,

I'm not even going to bother discussion with Todd any further on the subject. With every response he makes, he further contradicts something he has said previously in his article or on this thread.

However, the subject of plenum air flow real get my juices flowing. I've never been able to visualize how the plenum can evenly and efficiently direct air to all eight runners. Lots of research and product has been brought forth promoting improvements in the base and runners, but it seems the plenum has gone by without scrutiny. Towards that end, I'm am currently in the process of building a crude home flowbench(it always amazes me at the depth of knowledge available on the 'net) and have acquired two spare TPI intakes(how did I ever manage to get by before eBay ). However, in the interest of not reinventing the wheel, do you(or anyone else reading this) have knowledge of any previous research that has been done on plenum improvement?

My basic plan is to chop the 'lid' from one plenum and replace it with a piece of clear glass, to allow me to do smoke traces. Then I can 'see' actual airflow inside the plenum and can also test some ideas I have regarding improvements. The main problem I anticipate, will be devising a method to simulate the uneven pull during normal engine operation(all eight cylinders never exert the same amount of pull on the plenum simultaneously). However, I do have some crude workarounds in mind that should give an approximate simulation of this condition.

Any other thoughts you might have, on the subject of the plenum, would be quite welcome by me.

[This message has been edited by 88IROCs (edited November 27, 2001).]

Todd91SS

TPI is FAR from useless. However, it is far from a well-performing high RPM intake. It is perfect for mid range flat broad fun torque. The problem comes when most of us try to force them to make power at 6 grand. But if you realize your intentions of the motor, like for instance if you were building a marine motor, or truck towing motor, TPI would be a match made in heaven.

In addition, I hope that my article didn't come off with the impression that an L98 won't benefit from a good set of aftermarket heads. It certainly will! The question is, how much more potential does the motor have with a different intake design that supports power higher? I can definitely say that I have seen great gains with my cars with stock TPI and aluminum heads. But you know what? The gains were paled in comparison when the switch to the MR was made.

Add to that the work and progress we've made on LT1 motors and LS1's and it starts coming into focus. At least from my perspective.

If I had a million bucks, I'd get all your addresses of those of you with heavily modded motors and still running a LTR, plenum, upper/lower setup and I'd put on a big Santa suit and drop a MR down all your chimneys.

Ask the guys running them! Because few people went directly from the stock TPI to the MR. They tried the aftermarket stuff first.

Once again, I'm not seeing many other sources of information of this nature. Which surprises me considering how important it is to engine building.

Look at it from my perspective. And true, these are my opinions. Obviously. I experiment with just about every intake part made over a few years and finally come to what I think is the solution for many and sure as hell is the solution for my configuration. Wouldn't it make sense for me to try and share that information in the best way I could come up with?

Grim Reaper

That is not what TPI does to the torque curve. It makes it have a high peak and then quickly drop off. A Miniram promotes a flat torque curve.

I can't remember if it was Bob Wooten or Greg Westphal, but one of them built a large tube runner TPI and posted a dyno result. I recall that the torque line looked like Mount Everest. What was flat was the HP line from 4,500 rpm to 6,000 rpm. That (HP Line) looked like the horizon of Nebraska.

Todd91SS

I didn't double post. Really, I didn't. ;-)


[This message has been edited by Todd91SS (edited November 27, 2001).]

Todd91SS

TPI is great for mid-range. The main point is that it starts building great torque around 2 grand. Then all the way through 4500 or so. That's what makes it great for engines that spend most of their time in the lower ranges. And also why it makes a fun daily driver.

305sbc

iTrader: (3)

i read all your article but most of the details don't agree with things i've read other places that make more sense. i do agree that tpi is no good for performance and is why i got rid of mine.
yes i see where you mention the carb for performance. i realize the article is about tuned port though.
i think the larger tube runners are still tuned to the same waves but just move more air volume. it makes sense to use those on larger motors.
i think a good test would be to put a larger throttlebody on that 502 and see what the dyno says. that should tell you right there if it is a restriction. i think you can also tell by measuring vacuum in the plenum or something like that.
by the way the ls1 intake is much easier to remove and install than even a miniram. there is no distributor and you reuse the gasket without any sealer so it only takes minutes.
i wonder why ls1 is so much more faster. they say it has a much smarter computer.


------------------
1986 Iroc 305 small block chevy: ported heads, 1 3/4 slp headers, rpm intake(ported), 1.6 roller rockers, performance valvejob, titanium retainers, compcams conical valvesprings looking for cam.

[This message has been edited by 305sbc (edited November 27, 2001).]

305sbc

iTrader: (3)

maybe someone will come up with an ls1 intake system to fit on older smallblocks and the fuelinjected lovers will finally be happy because the ls1 has the best of everything and is easy to work on too.



------------------
1986 Iroc 305 small block chevy: ported heads, 1 3/4 slp headers, rpm intake(ported), 1.6 roller rockers, performance valvejob, titanium retainers, compcams conical valvesprings looking for cam.

Todd91SS

If you did in fact read my report, then you surely read the section on carbs and how they did work great for higher rpm usage. They are a perfectly acceptable replacement for performance purposes. Some though, like myself, prefer to stay fuel injected for whatever variety of reasons.

And as far as ease of working on it, the MR is definitely the easiest intake I have ever worked on including LS1's and carbed motors.

breathment

whoa man, i knew i shouldn't of replied to this topic and brought it up to the top in the beginnig, was just trying to be nice too.



------------------
- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16

Todd91SS

No, hell, I think it's great. At least it means that people are thinking about it. And that was the point after all.

irocbsa

Personally, I've enjoyed the discussion.
bsa

305sbc

iTrader: (3)

yes i saw it. i changed my post above.




------------------
1986 Iroc 305 small block chevy: ported heads, 1 3/4 slp headers, rpm intake(ported), 1.6 roller rockers, performance valvejob, titanium retainers, compcams conical valvesprings looking for cam.

Enkil

Well, it's just a start, but you can drop just one down my chimney for a lot less than a million.

------------------
89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

Todd91SS

305, the LS1's are much more powerful for a number of reasons. Saying the computer is "smarter" is true, but that's not the only source of added power. It's just a better way to manage the efficiency of the engine. The LS1's have better closed-loop control than in the past, meaning that the engine takes the sensors more into consideration when calculating fuel and spark curves. Our engines (TPI) are much more open loop, or relying on tables that are pre-programmed in the PROM chip, with limited ability to "learn" new curves based on sensor input.

A tremendous part of the LS1's power comes from its' mechanical internals.

Some of the main features are the use of 1.7 ratio roller rockers, the completely revised cylinder head design, with raised roof intake ports for a more direct inlet charge with higher velocity. This also gives a direct fuel injector firing path right into the combustion chamber.

The rod to stroke ratio is improved over the LT1's and L98's from 1.6361 to 1.6828. This provides quicker acceleration of the rotating assembly of the motor, and also leads to longer piston/ring/bore life.

The fact that the block is aluminum with iron cylinder liners certainly helps the weight factor.

This is also the first Chevrolet V8 to deviate from the conventional firing order, which puts excessive strain on the 5-7 main bearing cap and improving cylinder air starvation problems. The LS1 firing order is 1-8-7-2-6-5-4-3.

That any help? Even that's just brushing the surface.

88IROCs

The whole argument that the TPI intake is great for low-end but has limited top-end is flawed, because it assumes the intake is the only part of the motor that governs those operating characteristics. In actual fact, the restrictiveness of the factory heads and exhaust do more to choke-off the top-end(and ironically they also have a negative effect on the low and middle). Replace these components and you gain not only top-end but you will fatten the torque curve through the low and middle rpms also. Even beyond those components the stock camshaft will hinder the top-end capability more than the intake. The factory bumpsticks need short-duration and minimal overlap to maximize efficiency in the low and middle rpms to meet emissions and fuel economy regs. Unfortunately, using the cam to maximize the low and middle usually means you give something up at the top. Conversely, picking a cam with greater duration and overlap will help the top-end, at the expense of the bottom.

And then we get to the whole argument about how much low-end is usefull. Advocating the modification of a TPI motor to increase the already prodigious amounts of low-end torque seems silly, especially when it comes at the expense of not improving the top-end because you believe the intake is rpm-limited. With both of my L98s, I was able to spin the tires well into second(and occasionaly even able to get a chirp on the 2-3 upshift) on completely stock motors. What is the point of a ton of torque if you can't hook? Even with a stock motor, substantial suspension mods are needed to get traction on a consistent basis.

If you are building a motor for a C3500 C/C dually which is meant to tow a 35 ft 5th-wheel, go ahead and build the motor with a limited operating range and ***** of torque. You'll need it! But if you're building a motor for a daily-driver with attitude and the legs to back it up, a more balanced approach will pay dividends.

witchdr

Wow.

giovanhalen

The 502 will make good power with a 48mm TB because it is a 502!

TPI Guy

Todd, I read your report, and it isn't very good ... but it did have some cool looking pictures. Try looking here:
www.grapeaperacing.com
His tech articles are pretty good.

I think you spread yourself way too thin on this one. You didn't even mention the harmonics of the tpi, you very very breifly touched on the cam and made a lot of claims about the TB that you can't back up, plus you tried to say that John Lingenfelter expanded the plenum volume of the TPI for the sole purpose of meeting the new revised entry of the runners. Your report lacks technical information and concrete information to back it up ... but you did have some cool pictures, so I give you a 'D'.

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355 c.i.
Dart 180 Heads
Lunati 224/224 cam
Harland Sharp 1.5 rockers
Performer RPM Manifold
Holley 600 cfm double pumper
Hooker Super Competition Headers
Flowmaster Exhaust
Competition Engineering Sub-frame connectors
Tremec TKO
Pro 5.0 Shifter
GM posi 3.42 rear
Hurst Roll Control
13.9@102
http://www.geocities.com/thetpiguy/index.html
chemjoker@aol.com

Ed Maher

Damn, for once me and TPI guy are on the completely same page

Todd91SS

Well, at least it's not very good. I appreciate the comments.

I'll sure be looking forward to all your tech articles in the future relating to this topic. Next time I write one, I'll be sure to summarize what everybody else already knows to make sure no-one disagrees. It would be a shame to actually accomplish something with a tech article that is of any use.

All I can say is good luck trying to make modded TPI work and someday maybe we can get together and drive each others cars and talk about the reality of things.

Guest

Another thing that affects the flow much more than anything you stated is all the direction changes of the air from the air filter to the valve, and the complete lack of transitions between each part in the system. Someone mentioned the LS1 intake, and if you notice on that and the LT1 (and the miniram BTW) the crap transition from intake to head is completely gone. No fluid likes to change direction, and when you want it to more likely than not turbulence is introduced. When you ignore the transition (read:TPI) it makes matters 10x worse.

Todd91SS

Madmax, I definitely agree. I touched a little bit on that with the statement:

"Let's think again about the long runner design. It's rather obvious that taking the air and forcing it to turn corners and change direction would be much less efficient and less effective than a straight 4" shot directly into the combustion chamber."

There is definitely more involved than that. I was forced in this whole thing to minimize the amount of detail to keep it short and not bore readers.

88IROCs

Max,

I'm on the same tip as you on this one. At least once the air makes it into the runners, until it makes it's way past the intake valves, the moving air has walls to 'coax' it in the right direction. But before that, it has to move from a high-pressure(front of the TB) to low-pressure(back of the TB), do some tumbling and than make an abrupt turn towards a runner(aided to an extent by engine vacuum). At least that is what I visualize is happening(could be wrong, wouldn't be the first time). So once I get the jerry-rigged flowbench hooked-up, I want to experiment with some ideas I have about 'coaxing' the flow of air to the runners. Seems to me there has to a more efficient way of feeding the runners at higher engine speeds(could be wrong again(wouldn't be the second or fifth time ).

Also, after having pulled the plugs a few times this summer(oh joy, oh bliss!) it seems to me that 2 and 7 are running just a little richer than the rest. I'm not sure if this is an anomaly with this engine, or if it is a typical LTR TPI symptom. Either way, curing any flow imbalances should pay-off at the big-end of the track. To be fair, I switched to SLP runners and Iron Eagles(180cc) this past year so, I'll have to track down all the variables they might have introduced before I look for a cure.