Supercharger compression ratio

Jayjayducky2001

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Well I bought my 94 GT 5 speed about a month ago and I've decided I want to put a stage 2 Intercooled procharger on her. Yes I will be doing forged internals and all of the needed supporting mods for the suspension, transmission,fuel management, heads, cam, and anything else needed. I'll be getting it tuned for 93 because it is still my daily. So I'm trying to figure out what compression ratio will be the best as the procharger kit runs 14-22 PSI. I was thinking something around 8.5 to 1. Yes I know 14-22 PSI is a bit nuts for a street car but eventually it's going to become a dedicated drag or track car.
 

Michael Plummer

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I would build it for 9:1 to 9.5:1 for 93 octane. If you have the option of using E85 or a properly setup Water/Methanol kit, I would build a 10:1 or 10.5:1 setup. The 8.5:1 compression ratio thing is old school and makes for a very lazy setup.

Good luck
Michael Plummer
 

Jayjayducky2001

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I would build it for 9:1 to 9.5:1 for 93 octane. If you have the option of using E85 or a properly setup Water/Methanol kit, I would build a 10:1 or 10.5:1 setup. The 8.5:1 compression ratio thing is old school and makes for a very lazy setup.

Good luck
Michael Plummer
Sadly no E85 access at this time, it's also my daily for the time being so 93 is my best option right now. Would the 9:1 0r 9.5:1 be better? Or does it really make much of a difference?
 

ttocs

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not a what but a who @96blak54 has played around with compression and is who I would ask but now mr plummer gives great info as well when he pops in.
 

96blak54

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I have had an impact on ttocs with my naturally aspirated 18:1 5.4l 2v build. Engine ran beautifully on e85. Touchy as hell tho.

4" + bore diameter, street daily driven car, pump gas, id stick to keeping compression low and simply managable at something like 8:1_ 9:1 for forced induction.

Youre going to get alot of mixed answers, but to narrow this down it all depends on your build as to how much compression it will handle before self destruct grenading.
 

ttocs

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I have had an impact on ttocs with my naturally aspirated 18:1 5.4l 2v build. Engine ran beautifully on e85. Touchy as hell tho.

4" + bore diameter, street daily driven car, pump gas, id stick to keeping compression low and simply managable at something like 8:1_ 9:1 for forced induction.

Youre going to get alot of mixed answers, but to narrow this down it all depends on your build as to how much compression it will handle before self destruct grenading.
I recognize that its little experiments like this that allow you to know as much as you do. I wasn't joking when I said you are one of the dudes I would ask.
 

Jayjayducky2001

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I have had an impact on ttocs with my naturally aspirated 18:1 5.4l 2v build. Engine ran beautifully on e85. Touchy as hell tho.

4" + bore diameter, street daily driven car, pump gas, id stick to keeping compression low and simply managable at something like 8:1_ 9:1 for forced induction.

Youre going to get alot of mixed answers, but to narrow this down it all depends on your build as to how much compression it will handle before self destruct grenading.
Well it'll be forced induction using Prochargers stage 2 intercooled kit which is used for 14-22 PSI applications, I'll probably run about 16 PSI using forged internals and sleeves and possibly a 331 stroker kit. Still trying to decide what heads and cam I want to use but I do know I'll be using a 75mm throttle body, 76mm mass air meter, a 255 lph fuel pump, not sure what size injectors I want to use quite yet. I do plan on putting pacesetter long tube headers connected to a bbk exhaust and mufflers along with doing the smog pump and egr delete if any of that information helps. I'd like to make around 600 rwhp and I think I should be able to do that with 93 using a 9:1 or 9.5:1 compression ratio with the procharger kit and proper tuning. This is just my first real build and I don't want to send a piston through the block or break my Crankshaft in half because my compression ratio was too high. The only other engine I built was a 2004 jetta 1.8 turbo which sadly didn't even make it into the car before it killed itself and I don't want a rerun of that
 

95opal

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Well it'll be forced induction using Prochargers stage 2 intercooled kit which is used for 14-22 PSI applications, I'll probably run about 16 PSI using forged internals and sleeves and possibly a 331 stroker kit. Still trying to decide what heads and cam I want to use but I do know I'll be using a 75mm throttle body, 76mm mass air meter, a 255 lph fuel pump, not sure what size injectors I want to use quite yet. I do plan on putting pacesetter long tube headers connected to a bbk exhaust and mufflers along with doing the smog pump and egr delete if any of that information helps. I'd like to make around 600 rwhp and I think I should be able to do that with 93 using a 9:1 or 9.5:1 compression ratio with the procharger kit and proper tuning. This is just my first real build and I don't want to send a piston through the block or break my Crankshaft in half because my compression ratio was too high. The only other engine I built was a 2004 jetta 1.8 turbo which sadly didn't even make it into the car before it killed itself and I don't want a rerun of that
Your build is similar to mine and im at 9:1. As for injectors i wouldn't go anything shy of 80s
 

96blak54

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From my understanding its the stock blocks that give up around 500hp. You may want to look into it. Im not versed enough on the prushrod stuff to positive with my info.
 

Rons95GT

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You will need more than a 255lph fuel pump. I know this from experience running 10-12lbs of boost. I spoke to a lot of tuners and fuel supply manufacturers after I found out I was running lean with a 255lph. I went with an Aeromotive 340lph and 60lb injectors but you will likely need more.
 

ttocs

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You will need more than a 255lph fuel pump. I know this from experience running 10-12lbs of boost. I spoke to a lot of tuners and fuel supply manufacturers after I found out I was running lean with a 255lph. I went with an Aeromotive 340lph and 60lb injectors but you will likely need more.
were you still running the stock fuel lines by this time or were they replaced?
 

tvsn95

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You SHOULD be no more than 9:1. thats a lot of boost for the combo you are thinking about. you WILL need way more fuel system. 60lb are fine up to 750hp but you should probably start with 80Lb,,,Don't buy junk get Siemens the real one's made in America ( Power adder solutions ) Tell Chris what you want, He's a national dist .
You will need Big fuel rails and a remote regulator. You will need -8 supply and -6 return, you will need BIG pump/pumps. ( Hotrod hoses) DON"T BUY EBAY HOSES, if it is not teflon inside don't use it you will regret. I run 2 external 255's. have installed a 400l intank on the last turbo car and the jury is still out on that one. The Areomotive 340 WILL run out at the top. you can get buy fine with the stock throttle body on a forced induction and its a bit easier to tune, might as well save the $$.
 

Rons95GT

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96blak54 is correct about the stock blocks also. Use a Dart or Ford Boss 5.0 block, and use 1/2” ARP head studs with a cometic gasket.
 

tvsn95

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you would be better off starting with a 351 or a coyote if you want those numbers.
I have done the 351 thing and it works well BUT yo need a COMPLETE assembly with accessories, But remember that it is 1" larger in all directions.
the Boss 302 is what I use and it has All the good parts .
 

95opal

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you would be better off starting with a 351 or a coyote if you want those numbers.
May hold true with the 351 but not a coyote swap especially a gen 1.
 

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