280whp+ Borg Warner turbo set up

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08-27-2018, 10:54 PM

04MiataNoobster

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280whp+ Borg Warner turbo set up

I’m looking to build my 04 Mazdaspeed Miata to its true form. I want run a Borg Warner 6258 .80 Twin Scroll and 9.5:1 on pump gas 91-93 is the best octane I’m able to get as of my current location. I want to know if this is remotely possible or is this me chasing a dream?

08-27-2018, 10:58 PM

nitrodann

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It will work fine but you are going to be knock limited around 280-290 whp.

Dann

08-27-2018, 11:03 PM

borka

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Im running a standard T25 6258, and make about 300whp at 17-18 psi. on 93 pump gas.
rods only motor build with pistons out of a 94 miata. these supposedly have lower compression 8.8:1 or so.

280-300hp should be doable for you with proper dyno tuning.

08-27-2018, 11:20 PM

04MiataNoobster

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What would possibly help reduce knock? Stronger coils? Lower C.R.?

08-27-2018, 11:23 PM

borka

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Quote:

Originally Posted by 04MiataNoobster

What would possibly help reduce knock? Stronger coils? Lower C.R.?

lower compression pistons. 8.6:1 is ideal for high boost pump gas motors. pistons are pricey though ~$500 plus you need to bore out block.

08-27-2018, 11:25 PM

04MiataNoobster

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@borka
i want to run the stock compression ratio which is 9.5:1 and I like it for the fact it has a bit more acceleration before the turbo kicks up

08-27-2018, 11:32 PM

Savington

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I, too, choose to sacrifice performance from 2200rpm-7500rpm in order for a small bit of extra pickup between 1200rpm and 1800rpm

08-27-2018, 11:33 PM

04MiataNoobster

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@borka
i want to still stay at 83mm bore. I know staying at 83mm with 9.5:1 CR is going to require custom pistons and I wouldn’t mind the extra money spent

08-27-2018, 11:34 PM

borka

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Quote:

Originally Posted by 04MiataNoobster

@borka
i want to run the stock compression ratio which is 9.5:1 and I like it for the fact it has a bit more acceleration before the turbo kicks up

then your max hp ceiling will be knock limited. how much limited? no one knows. but you will find out when dyno tuning and listening for knock.
another way to reduce knock is methanol/water injection. i've never done it, so dont have much info about this.

im pretty sure you should be able to hit around 300hp with 9.5:1 pistons. on pump gas.

08-27-2018, 11:35 PM

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04MiataNoobster

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@savington
well what would you choose as a C.R.?

08-27-2018, 11:38 PM

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Savington

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Quote:

Originally Posted by 04MiataNoobster

@savington
well what would you choose as a C.R.?

8.6:1. I also build engines and sell the best Borg Warner turbo systems on the market for these cars, FYI, so I have a bit of experience doing exactly what you want to do.

08-27-2018, 11:40 PM

#12

04MiataNoobster

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@borka
Im not trying to run insane boost e10-15psi if possible is nice in my opinion. Would lowering the C.R. to 9:1 be any different in possible reducing knock?

08-27-2018, 11:45 PM

#13

04MiataNoobster

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Quote:

Originally Posted by Savington

8.6:1. I also build engines and sell the best Borg Warner turbo systems on the market for these cars, FYI, so I have a bit of experience doing exactly what you want to do.

From 8.6:1 to 9:1 would the difference in spool be a notice able difference at same psi or non at all?

-1

08-27-2018, 11:48 PM

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borka

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Quote:

Originally Posted by 04MiataNoobster

@borka
Im not trying to run insane boost e10-15psi if possible is nice in my opinion. Would lowering the C.R. to 9:1 be any different in possible reducing knock?

10-15psi will get you 220-280ish whp.
you can do that on stock pistons. Just install stronger rods.

or get forged pistons if money is no issue. With 8.6:1 CR.

9.5:1 pistons is for e85

08-27-2018, 11:51 PM

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Savington

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Quote:

Originally Posted by 04MiataNoobster

From 8.6:1 to 9:1 would the difference in spool be a notice able difference at same psi or non at all?

You will never notice, and you would be hard-pressed to measure the difference.

08-27-2018, 11:52 PM

#16

04MiataNoobster

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Quote:

Originally Posted by nitrodann

It will work fine but you are going to be knock limited around 280-290 whp.

Dann

what would be a better suited C.R. for my goal for power?

08-28-2018, 12:02 AM

#17

04MiataNoobster

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Quote:

Originally Posted by borka

10-15psi will get you 220-280ish whp.
you can do that on stock pistons. Just install stronger rods.

or get forged pistons if money is no issue. With 8.6:1 CR.

9.5:1 pistons is for e85

money is not an issue and thanks for the info.