SLAMMER Posted March 20, 2015 Author Share Posted March 20, 2015 8.61:1 compression ratio SLAMMER Link to comment Share on other sites More sharing options...
joe@cpr.com Posted March 20, 2015 Share Posted March 20, 2015 why on earth is it so low? I get your pump gas but still a mid 9 would be more than safe. Link to comment Share on other sites More sharing options...
HOXXOH Posted March 20, 2015 Share Posted March 20, 2015 You can easily go up to 15 psi at 8.6-1 safely. On my old blower, I was cranking the impeller to 60,000 to get 16 psi on 8.8-1 and that was with the old tech in the 70's. Link to comment Share on other sites More sharing options...
Unreal Posted March 20, 2015 Share Posted March 20, 2015 Holy crap. That is sadly low. Even a twin car shouldn't be that low. Ysi I would shoot for 10-10.3:1. Even my 9.8:1 is low for centri standards. There is zero reason to go that low. I would be pulling heads right now and swapping them to the smallest chamber you can find. Link to comment Share on other sites More sharing options...
HOXXOH Posted March 21, 2015 Share Posted March 21, 2015 Holy crap. That is sadly low. Even a twin car shouldn't be that low. Ysi I would shoot for 10-10.3:1. Even my 9.8:1 is low for centri standards. There is zero reason to go that low. I would be pulling heads right now and swapping them to the smallest chamber you can find. At 10.2 I blew a hole through the top of the combustion chamber. At 9.8 I blew through a piston. Forged were not available. I was already physically restricted on cam size and it was flat tappet too. Not a lot of choices back in the late 60's and early 70's. I did hold 3 National records with that car, so it's not like I was holding back a bunch. Link to comment Share on other sites More sharing options...
Unreal Posted March 21, 2015 Share Posted March 21, 2015 Technology has come a long way. A lot more control of timing, fuel, and piston/cam/head design/etc. Most vettes making decent power with centris are running low 10s. Talk to any of the big name fast shops. Point is, 8.6:1 is way too low and motor should never have been built like that unless it was getting a carb and a flat tappet. 9.8:1 here and 24psi with a Ysi, no knock, never hurt a plug, no issues. Only ~18k miles on that setup so far. Link to comment Share on other sites More sharing options...
Chameleon Posted March 21, 2015 Share Posted March 21, 2015 Wow, this thread has been totally hijacked. Link to comment Share on other sites More sharing options...
Unreal Posted March 21, 2015 Share Posted March 21, 2015 Into trying to help him get a better performing car and a setup that makes power? Just did a bone stock auto l99 car the other day, 12psi, made 660rwhp. TB to pan bone stock, never off the car, and that is an l99 motor, not a ls3 so starts less. No reason a Ysi built motor car should be <600, hell no reason it should be less than 900. Link to comment Share on other sites More sharing options...
Two Fangs Posted March 28, 2015 Share Posted March 28, 2015 For a small cam, low compression build, I think the numbers look good. I am not certain what SLAMMER's end power goals are (possibly 650?), I also do not know why nor who spec'ed the engine in the fashion that it was, but as long as he is happy, all's good in the 'hood. Regardless, I am sure you can understand folks coming in here and critiquing something that he obviously has a lot of time and money into could be perceived as more than just helpful advice. Especially since the whole thing just started as a guess the numbers thread. Let's all, myself included, hold the "things we would do differently" banter until that advice is asked for. Link to comment Share on other sites More sharing options...
Desertdawg Posted March 28, 2015 Share Posted March 28, 2015 Well said Mr. Snails ... Link to comment Share on other sites More sharing options...
Chameleon Posted March 28, 2015 Share Posted March 28, 2015 ^^^ X3 Link to comment Share on other sites More sharing options...
2thorth Posted March 28, 2015 Share Posted March 28, 2015 - 2 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now