Suggestions on built short block and compression ratio?

[SoCal80six]

Looking into getting a built short block not to sure on the cr though. I have a maperformance turbo kit with a precision 5858 turbo. I've had a few people tell me to stick to stock cr and a few others tell to go for around 9:1 or around a 10 not to sure what to do any help would be appreciated thanks

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[go_a_way1]

Originally Posted by SoCal80six

Looking into getting a built short block not to sure on the cr though. I have a maperformance turbo kit with a precision 5858 turbo. I've had a few people tell me to stick to stock cr and a few others tell to go for around 9:1 or around a 10 not to sure what to do any help would be appreciated thanks

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Do like 5:1 and run 80 PSI
JK

How much boost are you going to run and what are you using the car for?

[SoCal80six]

Originally Posted by go_a_way1

Do like 5:1 and run 80 PSI
JK

How much boost are you going to run and what are you using the car for?

Don't want to run anything in the 20psi area really. I was just running 11.5 on e85 and I'd say around 390,400whp so not looking to run insane boost just to hit those numbers again. And I'd mostly be using it as a street car occasionally drag, but more of a little drift car.

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[go_a_way1]

Originally Posted by SoCal80six

Don't want to run anything in the 20psi area really. I was just running 11.5 on e85 and I'd say around 390,400whp so not looking to run insane boost just to hit those numbers again. And I'd mostly be using it as a street car occasionally drag, but more of a little drift car.

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Go with the 10:1 then as you get more response and off boost power. You should beable to hit your 400whp easy with that, and still have a streetable car.

[spitfire481]

on e85, my 10:1 ran great with a 5858 and a 6262. ran out of fuel at 525whp on the 5858 with 1000cc's. with the 6262 we upgraded to a walbro 485 and a return fuel system and maxed the 1000's at 590whp. for what you want, id stick around 10:1. a lot more room for error and headroom than 12.5:1 in my opinion. the spool on the 5858 was great for the power it can produce at 10:1

[SoCal80six]

Originally Posted by spitfire481

on e85, my 10:1 ran great with a 5858 and a 6262. ran out of fuel at 525whp on the 5858 with 1000cc's. with the 6262 we upgraded to a walbro 485 and a return fuel system and maxed the 1000's at 590whp. for what you want, id stick around 10:1. a lot more room for error and headroom than 12.5:1 in my opinion. the spool on the 5858 was great for the power it can produce at 10:1

Do you recommend any company's that offer built short blocks? Been taking to full blown and they offer a built short block but their cr is a 9:1 I believe.

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[SoCal80six]

Originally Posted by spitfire481

on e85, my 10:1 ran great with a 5858 and a 6262. ran out of fuel at 525whp on the 5858 with 1000cc's. with the 6262 we upgraded to a walbro 485 and a return fuel system and maxed the 1000's at 590whp. for what you want, id stick around 10:1. a lot more room for error and headroom than 12.5:1 in my opinion. the spool on the 5858 was great for the power it can produce at 10:1

And are you still running that 10:1 cr ? If so what kind of internals?

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[spitfire481]

Originally Posted by SoCal80six

Do you recommend any company's that offer built short blocks? Been taking to full blown and they offer a built short block but their cr is a 9:1 I believe.

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i have a full blown motor. they offered 10:1 originally then just offered 9.5:1 as a standard package. they can do any ratio you want, just have to wait until the pistons come in. we did a few 9.5:1 full blown motors and they do really well on pump gas as well as e85. i guess that's why he offers it as the basic "go to" piston now for people who do not know enough about it to choose their own ratio. their built motor works great, just be sure to upgrade the valve springs/retainers during the build

[SoCal80six]

Originally Posted by spitfire481

i have a full blown motor. they offered 10:1 originally then just offered 9.5:1 as a standard package. they can do any ratio you want, just have to wait until the pistons come in. we did a few 9.5:1 full blown motors and they do really well on pump gas as well as e85. i guess that's why he offers it as the basic "go to" piston now for people who do not know enough about it to choose their own ratio. their built motor works great, just be sure to upgrade the valve springs/retainers during the build

What would you recommend the 9.5:1 or 10:1 how has yours been holding up hp,tq,miles?

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[Sportsguy83]

If you plan on truly staying with E85 and not going over 20 psi, I fully recommend you keep the 12.5:1 stock ratio. Only reason to lower comp. is if you're going for the big power (25+ psi) and/or need to get off E85 and run just pumpgas.

[350matt]

sorry but 20 psi is quite a lot of boost E85 or not and there's not a manufacturer out there running CR over 11:1 on a boosted engine
drop the ratio to 10.5:1 and you'll have far more headroom against detonation and not have to swing the cams out to lower the dynamic ratio

look at the rest of the industry and consider that the hundreds of engineers and talent applied to those engines and ask yourself why none of the comtemparies are running high ratio and high boost

[86drift]

Stay with 12.5:1 if you plan on running E85. Detonation isn't really a problem unless you're pushing big boost. All the engine really needs is stronger rods.

[stevo585]

Originally Posted by 350matt

sorry but 20 psi is quite a lot of boost E85 or not and there's not a manufacturer out there running CR over 11:1 on a boosted engine
drop the ratio to 10.5:1 and you'll have far more headroom against detonation and not have to swing the cams out to lower the dynamic ratio

look at the rest of the industry and consider that the hundreds of engineers and talent applied to those engines and ask yourself why none of the comtemparies are running high ratio and high boost

While true, OEM's also do not design for all out power. They have other considerations like emissions and long term reliability.

I'd stick with 12.5 as well if your going to run e85. Better response off boost and quicker spool.

[strat61caster]

dafuq

Talk to your tuner. You're in SoCal, I'd be on the phone to Delicious and whoever they recommend, whether it's MAP, Moto East, Element Tuning or whatever you decide.

Coming on here to figure out what you want and then dropping it off at your tuners shop going 'figure out how to make this work' is complicating the process.