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View Full Version : High Boost with Flat-Top Valves?



groovezog
03-25-2010, 08:36 PM
I'm currently boosted at 9psi, and planning to up the boost after I re-build my head.

I have a K24a1, and some Supertech flat-top valves. I'm wondering how much flat-top valves will increase the compression, and if it would be better to use these or the stock valves at about 18-20 psi, using 91 octane or E85. I'm also 5200' above sea level, and have a great K-Pro tuner.

Relevant mods to the head:
Cometic head gasket, .030 thickness
Skunk2 stage 1 turbo cams (will increase dynamic compression ratio???)
Supertech valvesprings, retainers
ARP head studs

Block internals are stock.

I tried some compression calculator online, but it was way off, so I was hoping that someone would have some insight and wisdom for me.

heyvortek
03-26-2010, 08:05 AM
im not sure about the valves but ditch the cometix head gasket and go OEM. i would do e85 since theres more potential in power. the only thing u would need is a fuel upgrade to handle more fuel since e85 is harder to burn. the k24a1 is that high in compression so i wouldnt worry about having somethin like a 12:1. stock block should b able to handle that much psi unless ur a noob and cant drive. im sure someone smarter will chime in. good luck and keep us posted on numbers

groovezog
03-26-2010, 04:32 PM
im not sure about the valves but ditch the cometix head gasket and go OEM. i would do e85 since theres more potential in power. the only thing u would need is a fuel upgrade to handle more fuel since e85 is harder to burn. the k24a1 is that high in compression so i wouldnt worry about having somethin like a 12:1. stock block should b able to handle that much psi unless ur a noob and cant drive. im sure someone smarter will chime in. good luck and keep us posted on numbers
Sweet. I've already bought the head gasket, but I think it will be fine. It's stock .030 so I don't think it will cause any problems. Why do you recommend against the Cometic; experience or research?
I didn't list my fuel setup, as I'm already boosted and have properly addressed that area. Walbro 255lph and Injector Dynamics 1000ccs should be plenty.
For the E85/91 octane, I'm not really debating between the two...I'm going to get a tune for both, and just upload the basemap for the fuel that I'm running, as well as the proper boost limit. I'm in Colorado, and E85 makes it hard to start an engine during the cold months, so I'll need the option to run 91 in the winter.

I think you're right. I probably don't have to worry too much about the compression ratio. I can't imagine that it will be that much higher than stock.
I will surely keep EPHatch current to my numbers.

talonXracer
03-26-2010, 04:47 PM
There is nothing wrong about using the cometic gasket with the K24A1 unless you plan on running a K24A2 or K20Z3 head, then you must use a oem gasket.

You should see approx a .2 point increase in compression from the flatface valves.

groovezog
03-26-2010, 10:24 PM
You should see approx a .2 point increase in compression from the flatface valves.
Awesome. Thanks for the info. I don't think a .2 point increase is much to worry about at all.