Hello. I am building a 454 with an 8.2 to 1 CR and intend to use a Vortech Ysi trim without an intercooler. I wondered if anyone knew approximately what the limit on boost would be with 93 octane fuel. Thanks
Printable View
Hello. I am building a 454 with an 8.2 to 1 CR and intend to use a Vortech Ysi trim without an intercooler. I wondered if anyone knew approximately what the limit on boost would be with 93 octane fuel. Thanks
Depends on the heads. Are these aftermarket or factory heads. What are the cam specs because this matters also not just compresssion. Since I take it this is a Carb motor your limited because of tuning under boost. Start with 6psi which will probably be the limit till you run the motor on a Wideband.
The heads are Brodix aluminum. I don't remember the part # offhand though. Comp recommended a .660/.680 110 LSA i think; maybe a 112. The cam is a hydraulic roller. I don't remember where I wrote everything down at the moment; only had about 45 minutes of sleep in the past 40 hours
When I input your cam specs I show you with a final compression of 9.25 based on a piston with a low dome. With 93 octane I just don't see you making over 6psi without retarding your timing so much to run 8-10 psi that you would make the same power at 6psi. So much to this but you really need to Dyno with a Carb and run a Wideband to shut it down if your getting lean between the primary and secondary opening. I had this problem on my Dual Paxton unit.
What would be the better carburetor to use with this setup; a mighty demon or a Holley 4150?
I had some well worked Holley 4150's on my dual setup and converted to EFI because I could not get the mixture stable between the primary and secondary opening. I was building this for a boat and carb is easier and better when out on the water but to much time invested when a Ford SB can be EFI so much easier. I have heard excellent results with the Procharger guys using the Demon.
Quote:
Originally Posted by silverss
Contact CSU for a carb that will work with a BLOW-THROUGH application....
its what i use & many others http://www.csucarbs.com
-Carm
Will the YSi be able to shift enough air for you to reach the limits with a low CR like that, a big cam, and a big engine ???
Im making 19psi at 7000rpm in my 382 LS1, Edelbrock 215cc heads, 224/230 on 115LSA cam, 8.5" crank, and 3.0" blower pulley
On 8.7:1 CR, mines fine on pump fuel.
Slippage aside, thats spinning the blower pretty damn hard ( 12 rib )
I'm not sure- I've never built a blower motor before. Vortech offers the Ysi as the universal big block kit. I actually decided to go with a Merlin block so it will be a 509 instead of a 454. I really just want to build something that I can drive anywhere and will last a reasonable amount of time. Vortech says the optimum compression ratio is 9:1 with the supercharger; should I stick with around an 8:1 or bump it up to a 9:1? I've been talking to Comp Cams about cams and what their recommendations are. There are too many decisions to make!