I have a 92 Z28 with a stock L98. How much of a gain can I expect if I have the stock heads worked on, or pull the stock heads in favor or Torquer S/R's?

 

thanks for the overwhelming response

 

https://www.thirdgen.org/forums/tbi/...-headflow.html

You'll have to look up what the Torquer S/Rs flow to compare them. The stock 083 L98 heads flow quite well when ported, and will make excellent power so it's a matter of choice between porting + rebuilding the heads you have vs buying new. I'd also suggest you search to find people that have bought/used/documented what they got with the Torquers..... because there's already enough info on what the ported 083s will do by following the links cited above.

HTH.

 

I can tell you that I know someone who flowed the stock S/R head not the torquers but that they couldnt even break the 200 cfm mark and flowed slightly less than that as cast. The torquers are probably not far off. The stock heads can probably flow just as much ported since the S/R heads were able to be ported to give it 250 cfm at .550. Should be able to get the same results with stock heads.

Heres is the actual graph from the heads.

 

thanks for the info, I'm leaning towards working on the stock heads

 

Even the worst pair of aftermarket heads are going to be (at least) competitive with a good set of ported stock heads, and they'll usually blow them right out of the water.

Personally, I saved my pennies for three years so that I could get my AFRs without going into debt for them, and I'd do it again if I had to. The design advantages (ports & combustion chambers) are just too much for a stock head to match...

Your best (performance/cost) option would probably be to look into the Vortec heads - yeah, you'd need a new intake, but they're still probably the best bargain out there...

Also, here's a comparison of budget (under $1000) cylinder heads.

EDIT: Here's a comparison between ported stock heads & a set of AFRs... (Not really a "fair fight", since AFRs are widely considered to be more or less "top-tier" heads, but it's instructive all the same...)

Good luck.

 

The 083 heads were used on early crate engines, they can support 300hp here are some flow numbers of World heads and others:
L98 aluminum $559. Each

Valvelift intake exhaust
0.100 56 49
0.200 120 96
0.300 160 123
0.400 186 140
0.500 196 155

World Iron S/R Torquer $374 Each
0.100 68 55
0.200 128 100
0.300 179 133
0.400 205 145
0.500 221 153

 

AFR heads are awesome, but alot. Trick Flow heads are very good. And now Patriot Performance makes heads for the L98 engine. You have alot of choices here. BTW, I would only buy aluminum heads and heads with about 64cc combustion chambers for the L98 350.

 

 

the Trick Flow and AFR heads both have large intake runners for a TPI set up. Going to a runner of 195cc or larger has to hurt velocity and low end torque, right?

 

Use the AFR 180s. Good flow and velocity. I just ordered mines

 

Well, what I looked at when I bought my AFR 195s was the flow requirements of a 350/383 ci engine. I also looked at the combinations used by some of the quicker cars I could find, & these heads seemed to work really well for the 350.

In a sense you're right, if you're using a TPI or LTR intake setup, it's going to be somewhat RPM-limited anyway, so a smaller port size wouldn't limit you as much as with a carb intake or the HSR that I'll be using.

BTW, I still think that you owe it to yourself to do a search on this site for the Vortec cylinder heads - I've even found a place that's advertised them for $475 a set (on p. 143 of Sept. '06 Chevy High Performance mag).

Hope this helps.

 

I was originally going put the vortec heads on, but with the added expenses of the intake manifold, bolts, gaskets, EGR adaptor, and other misc. stuff, it ended up being kind of pricey for me.