Can anyone give RWHP gains going from 1.6 RR to 1.7 RR OR
the difference in HP gains going to 1.7's vs. the 1.6's? Please let me know what mods you have as well. I realize the gains will be greater the more "work" has been done to the motor.

I'm wanting to install some RR in the near future and would like to see some results from what you all have seen. Stock, bolt-ons, cam-only, heads, etc.
Also, discuss which ones you have found to be the best to work with as far as changing out, adjustment(s), and durability!

Thanks,
Eric

 

The 1.7s might give you more power but I have heard there are valvetrain geometry issues with running them. Id stick with the 1.6s or wait till you find a cam just incase you need to run 1.5s.

Nice track times btw... thats bolt-ons only right?

 

Thanks and the geometry issue is something I was wondering about as well. Would you say 1.6's for most cam installs and 1.5's only for say the really big cams or solid rollers?

Oh, yes, bolt-ons only. I want to install the upgraded springs and RRs along with suspension work as everything is stock and getting mighty old and loose.

 

On this car 1.7 worth 14 RWHP over 1.6:

http://www.wku.edu/~nathan.plemons/h..._corvette.html

He also tried 1.8s and lost HP vs the 1.7s, but he didn't bother checking geometry and people were surmising that pushrod length was an issue (he used same pushrods with 1.6/1.7/1.8)

[edit]I should add that his flow sheet indicated that the heads should support the lift with 1.8s.[/edit]

 

The 14hp gain had help from the cam and especially the heads. I feel I need some 1.6's because of the amount of low backpressure I now have with the hooker longtubes and huge y-pipe. I did gain power and speed however not as much as I had expected to. I only gained 1-1-1/2 mph going to long tubes and 4" y-pipe vs. my manifolds. I believe if I wish to really be able to use and gain the power the Hookers can give me, I must up the RR's and maybe even a cam but at least the RR's.
When I raced before with just manifolds it was like my car would suddenly go into another gear when I reached a certain rpm and take off and now it doesn't.

Anyone else experienced this surge at higher rpms with your stock exhaust system before the header install?