bigchief

Hey i just wanted to know who's using these corvette heads on these forums, if there is anyone here that has them besides myself, please post your experience with them so that i know if i should use them, or toss them.

i've seen people get the following flow numbers out of them, i was wondering how much hp that could get me with a street legal camshaft:
140, 203, 239, 259, 256

i think the stock flow numberws of the heads are:
60, 115, 161, 184, 196, 199

right now i'm running my 305 TPI center bolt valve cover heads on my 355 which has been working out fine so far, the 113 casting heads also have 58cc chambers like the 305 heads.

sofakingdom

iTrader: (1)

That has WIDELY diffferent meanings to different people and in different places.

Flow numbers that people post on the Internet are highly suspect; not that they're lying or anything like that, it's more a case of difficulty in replicating them. For example, if you were to port a set of heads, I'd be willing to bet that your flow numbers would not equal mine; and I'd also bet that if somebody who actually knew what they were doing ported a set, theirs would be MUCH higher than mine.

Then there's the question of setup: did they flow them with a "cylinder" to replicate bore shrouding? With an exhaust pipe? What valves were in them: 8°? 12°? Undercut stems? What kind of valve job did they have?

In other words, don't read too much into "site X here says they got xxx CFM", because that may or may not be anything remotely attainable by YOU, and may or may not be measured the same way that site Y, which got different numbers, measured theirs. Same for magazine articles. Kind of like the articles where they build an engine and put it on a dyno: YOU will not build the same engine out of the same parts and get the same numbers, you can believe that. They don't write articles about motors that produced disappointing numbers, and they want to publish motors that produce higher numbers than their competing magazines do, built out of the same parts; so expect EVERY trick in the book to have been used, and every tweeek to the dyno setup to wring every last erg out of every motor, again very different from somebody who sets their dyno up to duplicate REAL-WORLD running conditions.

Taking all that into account, expect real-world flow numbers somewhere in the mid-high 220s on the intake side, and low-mid 180s on the exhaust, at their peaks. Which is good for mid 400s HP. In general, they will flow a little better than your 081s, especially on the exhaust side, once both are heavily ported. Stock, they are MUCH better than 081s; not least because of the intake valve size.

Also keep in mind, if you're going to run an ANYWHERE NEAR stock TPI on top of them, the heads aren't the limit to HP anyway; TPI is.

Aluminum heads require higher compression than iron heads to achieve the same power, because they allow more heat to escape into the cooling system. In other words, they're less efficient at the same compression. Ceramic-coating their chambers and exhaust ports helps quite a bit.

All in all, I doubt that changing to those heads will make a big difference in your setup, especially with TPI. As long as you have that and that crappy "RV cam" choking your motor, the heads aren't the limit to THE MOTOR'S flow; and so changing them will have relatively little effect. Likewise, having that grocery-cart rear gear slows the car down so much by pinning the motor's RPM permanently near idle, that to make your car go faster, you don't need to be working on the motor right now anyway, because THE MOTOR isn't the limit to THE CAR'S performance.

bigchief

well a little thing i forgot to add was that i would be going with an accel super ram intake manifold on this engine, i would never leave the stock tpi on it if i changed the heads/cam.

also, those flow numbers came off the TPIS website, i've called them before about the work, and they told me that they flowbench the heads before they ship them out to make sure that they match the numbers that they list on the page.

the cam i'd be going with would probably be in the upper 400 range for lift, around 230 duration, and probably 112 lobe.

Sonix

iTrader: (1)

If it's a roller cam, you'd be shooting for above .500" lift with 230* duration at .050".

How much would it cost you to ship your heads to TPIS to have them port it? I can't help but feel you're not getting your moneys worth on that one.

I'm sure Mwnova66 has run those heads on his (305 or 350 I can't remember...), and..... I forget who else. But as mentioned, don't even try to replicate someone else's numbers, especially mwnova.

Orr89RocZ

iTrader: (20)

yeah flow numbers is a crazy game. but for what its worth, LT1 heads are similar to the aluminum L98's and they flow 225 cfm or so stock and have been known to make over 400hp on motor.

so a mild port job on a set of L98's should yeild 220's cfm and be capable of 400hp or more on a nice 350 setup. thats a nice street car

bigchief

yeah well i havent been able to find someone else who has gone through TPIS with these heads, but i know that they are capable of making nice hp, so i think i'm gonna hold on to them since i got them for free, and use them on my street car. hopefully i can make nice power with them, but i know i'm gonna have to spend about a grand on port work first.

bigchief

anybody else have good experience with these baby's??!?!?!

Kevin91Z

iTrader: (1)

Now that the search is working you should find a shyt-ton of posts from people who are running these heads. I had them from 2001 to 2006 and have posted at least 500 times about my experiences.

bigchief

great thanks!