AFR 305s vs 781 oval ports

[Pat]

Well I got a chance to run my car this weekend but only on a crappy 1/8 mile track. The track is at 3000+ ft an has a DA in the 5000 to 6000ft range most of the time.

The car picked up 2 tenths an around 3mph in the 1/8 mile from last year with nealy identical conditions. I don't have time to post the actual results in the differences from the time slips but the above is what it comes out to.

I had posted early about the change under the "Real world results" post so this is to let you guys know what the results were for the fist time out. I will let you know how it does in the 1/4 when I get to run again.

[Pat]

Hi Guys,
Sorry I didn't get back sooner but our weather has been horrible this summer. Every weekend we have raced its been 95 to 100+ degrees with DAs in the 5000 to 6000 range.

The car ran 10.30s @ 131 to 132 in the heat with the 305 AFRs. Where it used to run 10.60s @ 127 an 128 with the oval ports.

This weekend it was high 60s an low 70s with DAs in the 3400 to 3700 range an the car ran its best of 10.10 @ 133.9 So I am happy with the change an I belive the small rectangle ports work great for a 468 an a 3400lb car. These heads were unported but do have the chamber CNCed.

I am still a beliver in the oval ports but think for a full out race car the small rectangle ports will make more HP.

[67RS502]

Looks like you picked up around 4mph, so far.
That means around 50+hp or so. Please keep us posted, and let us know when you hit them single digets. ;D
Whats the comp?
Sorry Pat its been too long I dont remember your combo too well. And were the 781 ported or just cleaned up bowls?
Thanks
Rafel

[Pat]

I have a backhalved 85 camaro with a 468, full cage all steel, weighs in at 3400 with me in it. Its got 12.5 to 1 pistons with a Lunati roller .685x695 an 269x276 on a 110LS. I run a HP 1000, turbo 400 with a 8" converter, 5000 stall(Needs to be higher) 14x32s with 4.56s.

Last year the car was the same other than it was a 460 with the oval ports. The heads were "781's" I had put the bigger 2.19s an 1.88 valves in an did pocket porting an a good multi angle valve job on them then back cut the valves for better low lift numbers. It ran 10.40s in the cool air of the fall an 10.60s to 10.70s in the summer heat.

I was very pleased with how it ran for what I had in it at the time. I do all my own work including building the car. The only thing I don't do is the machine work an painting.

I wanted to run in the low 10.30s in the heat an 10.1s to 10.0s in the cool air so thats why I went with the AFR 305s. I nearly went with a 496 an kept the ovals but I didn't want to go into the 9s because of the extra cost of upgrading all the safety stuff an the heavy suit in the heat. I also needed to take weight off the nose since its 58% nose heavy with the steel heads. It may still hit the 9s in some 1000ft air if we ever get any.(HA)

[FC]

What are rpm you shifting at and crossing the finish line at?

[Pat]

Shifting at 6800 going across at 7000 to 7200.