Top End Rebuild
Pro
Joined: Jul 2008
Posts: 699
Likes: 3
From: Millersville, MD
Considering the flow of the AFRs, I'd spend the money for a retrofit roller. Not cheap...but it allows us to get into a lift range to fully exploit the capabilities of the head while still retaining good street manners.
The AFR streets deliver 260/207 CFM flow at .500...so I certainly wouldn't do anything less than that for lift. A .500 lift cam in a flat-tappet is fairly radical, but a roller hydraulic is just getting started
What trans and gears do you have? That helps with the other aspects of the cam choice. I would also call AFR and the cam vendors to get their takes...and of course a lot of smart folks here with good guidance.
The AFR streets deliver 260/207 CFM flow at .500...so I certainly wouldn't do anything less than that for lift. A .500 lift cam in a flat-tappet is fairly radical, but a roller hydraulic is just getting started
What trans and gears do you have? That helps with the other aspects of the cam choice. I would also call AFR and the cam vendors to get their takes...and of course a lot of smart folks here with good guidance.
Look at this DYNO Tested Street Package. Very similar to what I have.
http://www.airflowresearch.com/chevy_dyno.php
Last edited by Vette79C3; Jun 10, 2010 at 02:53 PM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
You didn't do anything "wrong", the parts just aren't well-matched to what you want from the engine. I agree that it's not easy, and I get a fair number of "rescue" engines into my personal shop that suffer from nothing more than good parts, right parts...but not the right parts matched to each other.
For the AFR dyno run, they were clearly shooting for peak HP on the dyno. The torque peak is at 4500 RPM and peak HP at 5500; ask yourself exactly how much time you in those RPM ranges. The underlying issue here is that we all love to talk about HP, when in reality for most street engines it's torque we want, and we want it in the operating range we spend the most time in...typically off-idle to around 4500 RPM or so. Not true for everyone, and less so in a manual trans 'Vette for sure, but fairly common.
In the end, it's important during design to clearly understand the RPM range you want power in, and design for that range.
There may be other issues in play - remote troubleshooting is problematic - but yeah, my take is great heads, not the right cam.
For the AFR dyno run, they were clearly shooting for peak HP on the dyno. The torque peak is at 4500 RPM and peak HP at 5500; ask yourself exactly how much time you in those RPM ranges. The underlying issue here is that we all love to talk about HP, when in reality for most street engines it's torque we want, and we want it in the operating range we spend the most time in...typically off-idle to around 4500 RPM or so. Not true for everyone, and less so in a manual trans 'Vette for sure, but fairly common.
In the end, it's important during design to clearly understand the RPM range you want power in, and design for that range.
There may be other issues in play - remote troubleshooting is problematic
- but yeah, my take is great heads, not the right cam.
Pro
Joined: Jul 2008
Posts: 699
Likes: 3
From: Millersville, MD
You didn't do anything "wrong", the parts just aren't well-matched to what you want from the engine. I agree that it's not easy, and I get a fair number of "rescue" engines into my personal shop that suffer from nothing more than good parts, right parts...but not the right parts matched to each other.
For the AFR dyno run, they were clearly shooting for peak HP on the dyno. The torque peak is at 4500 RPM and peak HP at 5500; ask yourself exactly how much time you in those RPM ranges. The underlying issue here is that we all love to talk about HP, when in reality for most street engines it's torque we want, and we want it in the operating range we spend the most time in...typically off-idle to around 4500 RPM or so. Not true for everyone, and less so in a manual trans 'Vette for sure, but fairly common.
In the end, it's important during design to clearly understand the RPM range you want power in, and design for that range.
There may be other issues in play - remote troubleshooting is problematic - but yeah, my take is great heads, not the right cam.
For the AFR dyno run, they were clearly shooting for peak HP on the dyno. The torque peak is at 4500 RPM and peak HP at 5500; ask yourself exactly how much time you in those RPM ranges. The underlying issue here is that we all love to talk about HP, when in reality for most street engines it's torque we want, and we want it in the operating range we spend the most time in...typically off-idle to around 4500 RPM or so. Not true for everyone, and less so in a manual trans 'Vette for sure, but fairly common.
In the end, it's important during design to clearly understand the RPM range you want power in, and design for that range.
There may be other issues in play - remote troubleshooting is problematic
- but yeah, my take is great heads, not the right cam.
Thread Starter
Advanced
Joined: Sep 2001
Posts: 63
Likes: 0
I got to take the 81 out for a test drive over the weekend, and I haven't stopped smiling, man those STS baffles sound good.
The Hooker side pipes didn't fit very well, I'm not sure if that was due to having poly motor mounts, the raised ports on the AFR heads, or hookers horrible QC.
Here is what we did to install the pipes:
The pipes all installed:
I still have to cut the bolts down so the rocker molding fits, but I think they came out pretty well.
