slickfx3

they tell me it is a bottle neck, I look at it and say not really, I have a cut lid, they say the MAF blows, I say the hole looks big to me.

I don't have a problem, they say I can gain HP, Who's trippin?

how much flow does it support? before it chokes?

has anyone rigged anything else?

87 vette 81 big girl

The TPI system sucks to 99.999% of people in stock form.
You are the only other person here on C4 that thinks like me.

It can be made to work.

Just have to remember that it will never make Big Horsepower.
Its impossible because of the very long total length runners to the backside of the Intake valve.

The TPI does one thing better than any other GM style EFI intake system.
Make tremendous low end and midrange torque.

Spending hundreds or thousands in the TPI system is crazy to me.

To make Big Horsepower numbers over 550- 900 HP normally aspirated you need the right combination of parts, knowledge, experience assembling and blueprinting an engine, degreeing a camshaft in, and the ability to spin the engine 7K rpm's and higher.
Its simple mathmatics and physics at work if you do research on your own.

Build around the low end and midrange torque of the TPI.
Or toss the entire system if you need Big Horsepower to satisfy your needs.

Doing the latter myself with a 410sbc engine transplant.

brian

slickfx3

I do have the built 383 230/236 xfi, AFR heads, and I still think it's fine, who's trippin?

87 vette 81 big girl

I don't know who is trippin on acid.

Its not me.

There are a few members here on C4 that have built up 383's with a GM TPI style system.

If you are seriously drag racing shooting for 10's or 9's in the 1/4 mile normally aspirated the GM TPI will be a hinderance.

There is a C4 member lurking behind the scenes here with a 1984 Vette with 2,500 + HP turbo car that has dipped into the 6's.

He will blow the doors off of all of us here on C4.

He rolled it 210 mph last year.

The car will be back I think this year sometime.

Brian

Sandpiper59

I'm in the boat with you guys as well. I've done a bunch of motor crap over the past 30 years and learned a lot about what works and what doesn't in carb land. Not turning out to be hard to translate that into TPI land.

Way too many people think HP is the only answer to speed. It isn't, it is required for flat out top speed. Torque is what we all actually crave, most just don't know it. That's why our 240hp TPI's will flat out smoke a 350hp LT1 from the early 70's. If peak HP is at 6200, you only hit it once per gear. If you build a high torque motor with a torque curve that starts just off idle and is pretty flat right up, you'll fly! TPI does that.

Pick a moderate cam, smooth the flow every where you can, (porting etc) let it breath in and out and tune the chip for mid RPM.. You won't win a dyno war but you will do a decent 1/4, destroy any stop light idiot and have a car that responds from just looking at the throttle.

Can't find it now but there was an article with a TPI that was ported, cam was I think only in the high 270's, heads were either well ported or non-stock (can't remember the heads). End result was (only) something like 340hp but torque was over 475 and was over 400 for more than 3000 rpm, that engine would haul azz in a 3700lb car and you'd probably be better not using 4.10's in the back!

87 vette 81 big girl

That is all very much true.
With the little GM L98 aluminum or cast iron TPI Vette engine.

But when you run against a properly built up turbo car, Supercharged street car, C6, modded up C5, or a Modern V12 Ferrari......... a 572+ci Big Block Chevy,

You are going to lose on the street.

Believe I know.
They are on the streets here in Illinois when the weather still turns nice.

I love the flexibility of a good running GM TPI Vette,
But its not enough anymore for me.

I am not to old to drive fast or race yet.
Give it 20 or 30 years and I will be.

Brian

Sandpiper59

Agreed 100%, I personally just get irked when I see the mind set of some 'others' who's immediate response is 'ditch the tpi, you can't do anything with them'.

There is a ton of room left in these TPI's, so much so that I believe you agreed with me in a way. If you really need that much more power, changing a bunch of stuff (intake, valves etc) on these motors is a waste, you need to step up _everything_. Bigger block, different heads etc etc, but then, tranny, rear end etc etc to match..

87 vette 81 big girl

There are a seemingly million different ways to build an engine and the rest of a car like a Corvette.
No one is right till they are proven wrong.
Or is that till they prove to others they are right? lol

My 410 motor swap may turn to out to be a big flop or failure.
Time will tell.

Its hard to hurt a Vette TPI engine in stock form.
Have to run it out of oil 1st then beat on it.
I ran my TPI ragged over and over.
It just keeps going and burning rubber in town and moves fairly fast above 120.

Brian

vetteoz

http://www.thirdgen.org/techboard/al...ctor-info.html

Sandpiper59

Excellent article!
So a MAF engine will be held to 517 min flow up till the actual TPI which they don't list but based on the early Firebird listed, 500cfm through the intake. While the tubes can only be port matched, there is room in the plenum and some room in the base for more..

NASCAR Busch is limited to 390cfm carbs and produce 575hp out of 355cu inches, imagine that! Wish I had the money needed to make 575hp through a 390cfm carb, but still proves the TPI smoothed out to say 550 cfm can allow for good HP if worked right.

87 vette 81 big girl

Nascar is using Finite Amplitude waves to get voumetric efficiency of a normally aspirated engine to well over 100% at peak torque.

It would confuse the CHIT out everyone if I discussed the theory in detail here on C4.

We will call it spacetalk tonight that actually works. lol

Finate Amplitude not a very well understood concept to most of the hotroding public.

NASCAR employs the best in business.
Have many resources and $$.
They make it work to their advantage.
How they get away making big power with a small cfm carb.

Brian

vetteoz

The misunderstood problem with MAF is not the physical air flow though the sensor but how the '165 ECM " calculates " airflow.

http://www.thirdgen.org/techboard/di...-5000-wot.html

tehcarguy

I want more of your knowledge!

slickfx3

so you say the ecm's ceiling is lower than the stock maf..

that's good bc, I don't run lean on top, everything runs right so in theory, the stock air ducting is up to the task

87 vette 81 big girl

yes...

I was taught by the best in Midwest, possibly the world in his day.
Hes gone now.
died in 2007.
I have a million stories to share and much knowledge to help.

It did not come easy for me.
Took most of my lifetime of learning the hard knocks of becoming the mechanic I am today.

I am not better than anyone else here.
I don't claim to be.

There are dozens of talented home mechanics, a few other professional mechanics here, craftsmen, innovators, pro engine builders,race car drivers, and so on here on C4.

My mind is a sponge for remembering things I want to.
And many I don't care too.

I have to let many of you figure problems out on your own here at times.
I know 1st hand the personal rewards that comes with an individual fixing their own cars and modding it for better performance.

Or restoring their car.

I just try and help.

Brian R.

Sandpiper59

Interesting.. Had no clue how it would have been applied to a motor, although thinking of it I think I can grasp a basic idea. I'd knew the term sounded familier. I work in the Telco and CATV industry and in cable have to deal with standing waves and modulation issues involving ingress of matching frequencies on non matching sync. A quick Google of finite amplitude is basically why the term sounded familier.

Then again, in a very basic starting point, that is where TPI was going with the design. Using "shock waves" (harmonics) with tuned length runners that would hopefully 'push' more air into a cylinder than that cylinder can draw on its own.

tequilaboy

The good news is that both limitations can be easily overcome with minor programming and hardware changes.

All it takes is a MAF with increased measurement range, a larger housing diameter to reduce the air flow restriction, programming changes to rescale the fueling calculation, and the know-how to do so.

slickfx3

if the range of the stock MAF is insufficient for a particular application, when is that threshold met?

when you can't enrichen it enough on the upper end of the rpm range?

what housing are you talking about, aft the maf? or fore the maf?

87 vette 81 big girl

The original team of C4 engineers were 1,000 times smarter than most here on C4 give them due credit for.

Finate amplitude waves don't work like most think it does.........drawing a vacuum.
Once you understand particle movement inside of an engine entirely it will make perfect sense to you.
You have to erase in your mind what you think actually happens inside of every internal combustion 4 cycle engine 1st.

It blows most every known hotrod theory out of the water and turns it upside down.

The technology in place dates back to WW2 when the USA had to go against the world with piston powered airplanes, Allison V12's, Rolls Royce Merlins V-12's, giant 18+ cylinder radial engines.

Roller Tappet cams, Roller Lifters, high octane gasoline were developed out of necessity to win against the enemies in the sky, water and on the ground.

Once you fully understand Finate Amplitude waves, you have to put it into real world use to make more power if that's what you desire.

Where I am exactly at with my 410 sbc prototype longblock my late friend built and left me to finish.

He said I had the knowledge and talent to finish it for him among other spoken words.

Brian

davenbocafl

yea, an edlebrock intake and a holley, that fi is pittiful when it comes to air flow, and the second is the cam if you go that far, you can pick up about 100 ponies and much more reliable and less expensive to maintain