This is what I was thinking.....take a Edelbrock TPI baseplate and port it like MadMax did but make it Oval not Sunglasses shaped, The port some SLP Semi Runners to match and do the same at the Plenum. Then as a finishing touch make the 48mm TB into 52 and add an Airfoil and set up a RamAir Intake. Where do you think the Torque and hp peaks would be with some aftermarket heads and a full exhaust. Hummmm.....

 

About 330hp and 420ftlbs

------------------
1991 Z28 ZZ4 with LPE superram base, SLP runners, LPE 58mm T-body,Random Technology ramair,TES headers,24#svo injectors,and just about every other bolt on that there is. Just got a ZEX nitrous kit!

 

whoops sorry, ment where were they RPM wise? I just doing madmaxs job raised the hp peak to some were in the mids 5s IIRC.

 

Are ya plannin' on upgrading the valvetrain? Are ya plannin' on upgrading ignition system? Are ya plannin' on burnin' a new PROM to take advantage of all the new parts.

Don't take this the wrong way but, there's more to it than throwing on the latest mad mod or hot parts. Keep in mind MadMax is only modifying one part of the whole system. This makes it a lot easier to keep track of the gains and fix the losses.

Pick up the last 5 or 6 back issues of "GM High Tech Performance" and look for articles on "Magnum TPI". This will show what happens when you throw a bunch of mismatched parts together without a plan. And then pick up the latest GMHTP(bundled with "Popular Hot Rodding") to see what happens when you put too much emphasis on performance, and not enough on maintenance.

 

Yes as a matter of fact I will match everything to the higher flowing TPI thank you very much. I am about to completely rebuild the motor soon and upgrade to a more RPM friendly NEW VALVE TRAIN, this is why i ask where do you think the RPMs will go to so I won't overdo the Valve train and pend un neccissay money. I am also getting into PROM burning. The ignition system was going to be upgraded but I don't with what yet, since you seem to be so smart why don't you give reccomendations instead of just sitting there and and criticizing me like I am stupid, some people on this site are so Fn' useless. It will eather be a High Flow TPI or a RamJet if the TPI does not flow to where I want it to. And yes I know about the RamJet, go look who started the huge 110+ post on it.

[This message has been edited by camaro6spd (edited June 23, 2001).]

 

Ok, ok, calm down. I was not criticizing you.

I was simply asking if you were aware of the other systems that needed to be changed to take advantage of drastic changes in the intake system. And to point out how difficult it is to track down down a problem, when you've made multiple changes at once. Like I said(or inferred anyways) when you make too many changes at once, it's asking for trouble). Unless you have a clear plan in mind(i.e.,... someone else has done what you are proposing and you can learn from their experience and avoid their mistakes).

As for cam recommends: with the system you are asking about - I'd aim for a HP peak of around 5500 rpm, with the torque peak between 4000 and 4500. The system you suggest is untried(to the best of my knowledge) but a cam with duration(@ 0.050) of 218° to 224°(268 - 276° adv) on the intake lobe should get you close. On the exhaust side add about 8 - 14°(@ 0.050) more duration. If you get it on a dyno, and it lokes like it could take a bit more cam, you can always retard the cam moderately(2 - 4°) to raise the HP peak. TPI engines usually respond well to some moderate retardation anyways, but you'll want to check your valve clearances carefully when you do this(min. clearance should not be below 0.100"). TPI engines don't seem to like a lot of overlap, and consequently lobe seperation angles matter a lot(aim for LSA's between 112 and 114°).

As for a specific cam recommend: the CompCams CS-268AH-14(p/n 12-404-4) paired with 1.6 ratio rockers would work for a torque-biased engine, and the 276HR-14(p/n 08-305-8) for a HP biased engine. Both of these cams will want a fair amount of compression( >10:1 ), so you'll probably want to match aluminum heads to this combo.

As for output, I've got three engine analysers I could fake it on, but none of them seem to model TPI especially well. To be fair, I think this combo would act more like a single-plane manifold anyways. But for the money and effort involved with this system, you should expect at least 400 hp or 450 lbs/ft(depending on which way you bias it).

Cheers!

[This message has been edited by 88IROCs (edited June 23, 2001).]

 

I guess the big question trying to be asked, or should be asked, is with doing all of the port work suggested, what kind of intake system is it going to act like? Compairable to a mini-ram? a super-ram? dual plain manifold, or single plain? Whats is rpm range like (ie..2000-6000)?
Anyone know?

------------------
Rob
'86 TA 305 TPI
Gutted MAF, Ported Plenum
TB Bypass, Home made Cold Air Intake,
Edelbrock T.E.S.

 

The length of the runners dictates the peak rpm that hp will occur at. Shorter the runner, more rpm, higher the hp peak.

 

It's more than length. Our 21 inch TPI runners SHOULD have the strongest harmonic at 5600 to 6800. The TPI doesn't underperform so much because of length or size, it' mainly because of the curves. That being said, siamesing does buy you some high rpm flow.

 

the length of the runners has very little to do with peak horsepower rpm. rather it is the ability of the entire intake system, including the plenum, runners, base and heads which will have an impact on where peak horsepower falls. or more specifically, it will be the ability of the entire intake system to supply the engines increasing demand for air(as rpm rises) that will aid or restrict an increase in a higher rpm hp peak. but even more important than the intake(in terms of determining peak horsepower rpm) is the selection of camshaft. throw a rv cam on a mini-ram, and you'll have good low-end, some mid-range, and nothing above 4500.

if the runners should be tuned to any point, it should be near the torque peak. this is where the engine reaches it highest volumetric efficiency and you want the intake to move the maximum amount of air per intake cycle.

as for the limitations on the stock tpi,... pairing the stock intake componenets with good heads, exhaust and a cam can significantly raise the peak rpms. with a 350, the stock intake components can supply enough air to reach peak hp at 4800 rpm or higher. with a 305, 5000+ rpm is attainable. again, it comes down to the supporting cast.

want proof? pick up the latest edition of "Camaro Performers" magazine. on a lightly modified 305 tpi the numbers came in at 274 lbs/ft @ 3800 rpm and 215 hp @ 4500 rpm. not very amazing numbers but a good baseline, as it is almost identical to what early LB9's were capable of. for the second test, the only components that were changed were the cylinder heads(from stock 305 heads w/ valve job to bone-stock, "out of the box", World "305 Torquers"). the numbers climbed to 336 lbs/ft @ 3600 rpm and 266 hp @ 5000(the highest dyno rpm that was recorded). again it bears repeating, the entire intake was stock(plenum, runners and base) and even included the "retrictive" 48mm TB. for both combo's. it kind of goes to show that the runners do not limit upper rpm horsepower as much as a lot of folks believe. and it kind of points out the benefits of matching components to their intended use(though this combo was far from optimized).


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

 

Rpm wise I think it should pull to 6000 with the right cam (some thing in the mid 220s duration), some ported AFR heads and a 1 3/4" header. It should be similar to a good superram combo my 2 cent worth. I dont see y it couldnt make 450hp/450-500tq.

------------------
91 B4C 305 TPI - SOON TO BE 383
TREMEC 5-SP, STOCK 1-BOLT REAREAND w/342 GEARS, K&N, AIRFOIL
EDELBROCK HEADERS, DUAL CAT TO HOMEMADE Y-PIPE & 3.5" SINGLE PIPE W/ FLOWMASTER, CRANK PULLEY, MSD, FUEL PRESS REG, COWL HOOD, WELD WHEELS
14.1@ 98MPH
-------------
OTHER RIDE
67 CAMARO - STREET CAR, BIG BLOCK, PUMP GAS
350TH w/ATI 10", 12-BOLT w/373 GEARS
10.94@124.13 ON MOTOR - ET-STREETs w/MUFFLERS

 

There's enough folks in third gen's doing low and mid 12's to disprove the fallacy of the TPI's so-called rpm limitation. Hell, if ya look hard enough, you'll find some who've dipped into the 11's using long-runners(without boost or juice). Now mind ya, those kind of times usually involve writing a big check to someone like John Lingenfelter. But I guarantee, you don't go that fast with a motor that runs out of breath below 5000 rpm.

I'd say in general TPI is a very good starting point, with a lot of potential(which is probably why GM gave up on it). And though the execution was mediocre(weak heads, sucky exhaust and limp cams), the aftermarket and a lot of enthusiasts continue to redefine how far it can go.