I'm having a tough time wrapping my head around all of this cause I'm very new to forced induction applications. So if I shoot for lower compression I can run more boost, but how much? At first for my build I was only wanting to run about 12 psi. But I have the chance to get some 95cc combustion chambered heads that would drop my compression to 8:1. I guess what I'm looking for is a way to find out with compression ratio+boost what would be my new compression ratio under a different psi. Also was wondering if the information I put into the compression calculator looks correct. I have no heads for my engine. So that's why the combustion chamber for the heads change.

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https://www.theturboforums.com/threads/best-compression-ratio.299658/

Decent discussion from an older thread.

 

Thank you @ss496

 

https://www.theturboforums.com/thre...ally-give-you-more-cubic-inches.374031/page-2

 

https://www.rbracing-rsr.com/compression.htm

With your cubes it probably doesn't matter too much, if you've got good heads and some stall you will make plenty of power off boost unless the car is really heavy. Turbocharging largely negates the need for a quench zone so your good there too. Your not at a high altitude, so your not paying a major penalty for the moderate CR. The 460's absolutely chug gas, a little more compression might help this but in the grand scheme of things going up a few percent at 8 MPG isn't going to matter much.

Cam selection is going to play a big part in compression ratio selection as well. Most turbo friendly cams don't bleed of a lot of cylinder pressure in low RPM so that will keep it from being too doggy out of boost. And if I remember correctly your planning on running intercooled and to shift at 5500 so with a baby cam and careful turbo selection you could be making power very early in the rev range.

Based on my experience I would still tell you to hold out for a set of c8/c9/d0 heads, or even better quality aluminum ones. But I don't know your schedule or budget. If the 8:1 (d3?) get you up and running and that's what you need then do it, will be fine.

 

Car is probably just at 4000 lbs it has a 2800 stall in it currently. I dont really have much of a schedule for it needing to be done at a certain time. I'm very stable with money so if necessary I would be fine with buying heads on credit if it's necessary for the best outcome I dont mind that to much. Thank you for the calculator that seemed very helpful. I'm still on the fence with the cam I have .599 lift 248/248 @.050 112 lsa.

 

When I see those 050 duration numbers I don't think of a 5500rpm stock rod engine. I think that cam is rated 3400-7k RPM. Which means more stall, forged rods, more head and big turbo.

 

^x2

 

You're the second person to say it was a bit to much, I'm not a whole lot interested in going above 6k of rpms after my last engine blew up.

 

if you want to know compression ratio based on boost
Wallace racing has calculator you want and more.

http://www.wallaceracing.com/Calculators.htm

 

Hot damn that's alot of calculators! Thanks @tbird

 

Currently building a twin turbo LS 403 stroker. C/R is 8.5:1. All forged internals. Here is an article that I always go back to reading and is the basis of my engine.

https://www.xcceleration.com › cr-b...
CR & Boost 101