TPIi

I am researching upgrades to a stock speed density TPI system on a 5.7L 350 cid engine. I am wondering what is a better investment: a high quality set of aluminum heads or a Vortec compatible TPI intake(like the one being commissioned by sdpc) and Vortec heads? Thanks for your input.

DON 88T/A

How much money you got and how fast do you want to go....you can answer ths question yourself.

Vortec's are good out of the box...but what you see is what you get.
They don't respond a whole lot to porting nor bigger valves.(a little anyway)
They are iron so,yourlimited in compression a bid deal if you want to stay N/A. Remember its an extra 20hp or so for every poimt ofcompression

But they are cheap.

After market Aluminum heads are light, can run higher compression,and respond well to porting...they already have good valves in them.

I figure for the price of the vortec heads and the intake to run them,a little more money and you can get a nice set of aftermarket aluminums...

Remember as well,if you upgrade the heads on a tpi you will really need to upgrade every thing around them to get the full potential...i.e the stock tpi cam won't allow enough breathing to realize what a good set of aftermarket heads are capable of.
As well the intake manifold,exhaust etc.

88IROCs

I've seen numerous posts claiming the Vortec's offer the most bang for the buck but I wonder. Considering the extra machine work(bare Vortec's are notorious for the roughness of their castings), new valve seats(Vortec's are machined for 1.94/1.5 valves) and new pistons(Vortec's 64cc chamber would net 10:1 comp on typical L98's), and the Vortec don't seem quite the bargain. Add in the cost of $400 for a new base manifold(most other aftermarket heads offer a version for your stock base) and setting up a Vortec/TPI combo becomes downright expensive. By my accounting this combo could cost $1000 or more. By that time you could have bought a set of TFS or AFR heads that are ready to bolt on and probably will give you more power.

<--- (groaning because the Vortec faithfull will probably be forming a lynch mob when they read <u>my opinion</u>.)

DON 88T/A

Well don't worry 88irocs,I'm in this too LOL

Seriously,I agree the aluminums would be a better choice...and if you don't want to go that fast(mid/low 13's) the stock heads are fine.
Just do the fullintake/exhaust overhaul,converter,..slighty larger cam to allow for more breathing,and with great tractin who knows?Maybe a high 12..

TPIi

Hey, I greatly appreciate your opinions. That's what I thought too. Comparing the cost of the Vortec installation equals a good pair of aluminum heads. Do you know who has the best prices on the aforementioned heads. What cam can you recommend for high low to mid torque? This set up is actually going in a Chevy powered Toyota Landcruiser. Please don't shoot me! I'll take the blame and lynching.

88IROCs

Actually I'm not in favor of/or against any one particular head. Your intent and/or budget will determine which head is right for you. I'm not even necessarily in favour of aluminum vs cast iron(aluminum needs extra compression to make the same output as cast iron, due to lower thermal efficiency).

The heads I plan on upgrading to are 180cc or 200 cc Iron Eagles. They are the right head for the engine I am building, but compared to Vortec's they have less potential out of the box. But seeing as I can port the exhausts myself(I did 4 cast iron heads last spring - 2 for practice, 2 for real) and can get the intake seats replaced for cheap(beers and nachos), assembled Iron Eagles make sense to me(at about $750/pr). If I had to pay someone else to do this work, then I might be looking at a different set of heads.

As for your application I have a couple of thoughts:

1. The Landcruiser/TPI sounds like a cool combo(I have an LB9 in my S15 Jimmy).
2. If all-weather operation and long-term durability are concerns, I'd choose cast-iron heads for your motor.
3. If low-end grunt is very important and the motor will never see 4000 rpm(which is the case with my Jimmy), build the motor accordingly. Again I'd pick the cast-iron heads as their better thermal efficiency will help the low-end(180cc Iron Eagle's would be my choice). Pick a cam with short duration(max 212°/218° @ 0.050") and minimal overlap(30 - 36°; ) to maximize cylinder filling at low rpm's. For headers, I'd try to find a pair with 1 1/2" primaries and really long collectors(again to maximize low rpm cylinder filling at the expense of some mid-range and any upper rpm breathing.) The stock TPI intake should work well for this type of application(but port-matching won't hurt).


[This message has been edited by 88IROCs (edited January 21, 2001).]

85F-body

ok i know this is a very very very stupid question but what are heads (i ask some stupid questions i am reputable for it)

88IROCs

1. there are no stupid questions, but stupid mistakes happen mwhen you don't ask enough questions
2. "heads" are short form for cylinder heads. these join the intake and exhaust manifolds to the cylinder. the valves in the heads control how fast and how much air is allowed into the cylinder(intake valve), and how efficiently the burnt mixture is removed from the cylinder(exhaust valve). the valve's motion is controlled by eccentric lobes on a common shaft(the camshast or cam). this motion is transferred to the valves via tappets("lifters"), pushrods and a lever arm(rocker arms or "rockers").

JJ

vortec heads will retain same compression on a stock piston L98 - both are 64cc, so it is either 9.3 or 9.5 to 1, can't remember which right now. I noticed the stock vortec headed thirdgen in gmthp went 13.0 - granted it had the ram jet, but the cam did not seem to be anything special either.

------------------
87 IROC, 350/5 speed. gmpp 350, vortec heads w/some work, XE268, 1.5rr's, 650dp, rpm intake, MSD ing., ect.
89 formula, L98.

TPIi

Thanks again for all the input. About the Iron Eagles, you said that if you had to pay someone else to do the porting and the intake seats you'd be looking at other heads, right? Why? Would that increase the price to much? At this point I don't have the ability to port myself or by a friend. Say you were in the market to buy some heads and the only mods you could procure were what you could buy already assembled and machined, can you say what those would be?

As for exhaust on the Landcruiser, I am running Corvette ram horn manifolds with 2 1/2 in. pipes and dual 3 chamber Flowmasters. Will having this much open flow cut down on low end torque?

And as for port matching, you mean basically porting the heads, intake, and exhaust to matching measurements?