10:1 Compression and boost

[Rolltide1006]

Hello all, happy Friday. So today I had a sit down at my local performance shop to go over supercharger applications for my 97 GT. The motor has been rebuilt. I kept the stock block and stock crank. I added Mahle forged pistons, Scat forged rods, PI heads with Manley valves, PAC stage 2 valve springs and Cms 2.5 blower cams. The shop that built my shortblock didn’t mention compression to me. I just told them I want to put a blower on the car to make 500 at the wheels. Well I did the digging today and found out my compression is 10:1 I can’t get a Kenne Bell because of this, but what would be safe to reach my goal? I figure I will only run 12-15 pounds of boost. T-trim for the save? Any help or advice is appreciated!


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[03cobra#694]

Low boost turbo.

 

[Rolltide1006]

Low boost turbo.

I would if I didn’t have blower cams and long tubes installed


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[03cobra#694]

Any forged parts?

 

[03cobra#694]

Oops, missed a bunch of your post.

 

[03cobra#694]

Nice centrifugal blower for sure. I’m not well versed on those though.

 

[Rolltide1006]

Nice centrifugal blower for sure. I’m not well versed on those though.

Ya that is what it’s looking like. I want to stay on 93 pump gas too. I would imagine a T-trim but I don’t have any experience with centris.


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[DSG2003Mach1]

I don’t see why that would prevent using a PD blower, depending on how much boost ya gotta watch your timing but that’s gonna apply to any source of boost.

I don’t know 2 valves well...my Mach loved boost on a built 10:1 motor. Maybe look in the blower boost/power thread for similar builds?

 

[jaxbusa]

I agree with DSG2003Mach1. Where did you hear you can’t? You’re only, like what, .5 more than stock compression? New coyotes have higher compression with PD.


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[Rolltide1006]

I don’t see why that would prevent using a PD blower, depending on how much boost ya gotta watch your timing but that’s gonna apply to any source of boost.

I don’t know 2 valves well...my Mach loved boost on a built 10:1 motor. Maybe look in the blower boost/power thread for similar builds?

For sure, thank you. Your mach was cool on it because you had a forged crank lol.


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[DSG2003Mach1]

500 hp isn’t gonna hurt a non forged crank

 

[Rolltide1006]

500 hp isn’t gonna hurt a non forged crank

I know but with the compression being high, guys are telling me to run e85 or meth injection. Im am hoping to stay on pump gas.

 

[98 Saleen Cobra]

1st, you can't compare a Coyote engine to a pi headed GT engine. Variable cam timing plays a huge role with cylinder pressure lol.

2nd. T-trim will more than get you there, but if only 500rwhp is what you want you could go SI trim as well. I've had a S/T/and now JT trim.. Wishing I had a YSI. I made 670 with the T-trim on 17psi without even trying on my 4v engine..

Compression isn't high. 10:1 on 93 you need to keep boost around 12-13psi range to be safe.

 

[Rolltide1006]

1st, you can't compare a Coyote engine to a pi headed GT engine. Variable cam timing plays a huge role with cylinder pressure lol.

2nd. T-trim will more than get you there, but if only 500rwhp is what you want you could go SI trim as well. I've had a S/T/and now JT trim.. Wishing I had a YSI. I made 670 with the T-trim on 17psi without even trying on my 4v engine..

Compression isn't high. 10:1 on 93 you need to keep boost around 12-13psi range to be safe.

My performance shop I go to said I would need something bigger than a S-trim to get to 500. He mentioned a T-trim and that would be my choice at this point, but I am waiting for him to build me a setup to safely run. I am hoping to hear back around this coming Wednesday


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[DSG2003Mach1]

1st, you can't compare a Coyote engine to a pi headed GT engine. Variable cam timing plays a huge role with cylinder pressure lol.

2nd. T-trim will more than get you there, but if only 500rwhp is what you want you could go SI trim as well. I've had a S/T/and now JT trim.. Wishing I had a YSI. I made 670 with the T-trim on 17psi without even trying on my 4v engine..

Compression isn't high. 10:1 on 93 you need to keep boost around 12-13psi range to be safe.

What this guy said... I ran 15psi on 93 but my timing was set to 14 absolute max If air and coolant temps were in the correct range

 

[98 Saleen Cobra]

My performance shop I go to said I would need something bigger than a S-trim to get to 500. He mentioned a T-trim and that would be my choice at this point, but I am waiting for him to build me a setup to safely run. I am hoping to hear back around this coming Wednesday


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You can go with the T-trim.. BUT for what it's worth. AED built a 2V with a SC-trim.. 700rwhp lol. 9.5 compression, stg 3 patriot heads, stock intake, 105 octane. So it can be done.. Will it be easier with the new Ti-trim?? absolutely.

 

[Rolltide1006]

You can go with the T-trim.. BUT for what it's worth. AED built a 2V with a SC-trim.. 700rwhp lol. 9.5 compression, stg 3 patriot heads, stock intake, 105 octane. So it can be done.. Will it be easier with the new Ti-trim?? absolutely.

Impressive! But I would like to stay on pump 93. I just started looking into this methanol injection action.


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[98 Saleen Cobra]

You won't need meth if you have a good air to air intercooler.. The car on 91 octane made 600rwhp

 

[Zemedici]

And please don’t rely on meth as a safety net.

As added insurance, sure. As the main source of cooling....just makes me nervous.

 

[Rolltide1006]

You won't need meth if you have a good air to air intercooler.. The car on 91 octane made 600rwhp

I hope so. I go to Injected Engineering and am working with Eric. Talking with him, he says he is going to build me up a ticket on what I need to get in order to get 500. Once I have that info I will know if I have to go meth injection or not.


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