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Old 11-20-2017, 03:12 PM   #1
pcampbell
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Default 253 with 100 octane

Anyone tried pushing an EJ253 to say 10 or 11 psi or so with 100 octane gas or E85...
These guys seem to think it'll hold/

http://www.cgperformance.com/subaru_turn-key_motors.htm

I was thinking of this as an interim to 257 block which I'm not quite ready for...
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Last edited by pcampbell; 11-21-2017 at 02:49 PM.
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Old 11-27-2017, 06:50 PM   #2
PA-Outback2000
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100 octane is not needed, ever. please stick to your original plan.
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Old 11-30-2017, 03:09 PM   #3
pcampbell
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I decided I want to bump up the boost on stock motor for now. If that means only 8 psi that is OK, but I think we can go higher with more octane to prevent detonation.
Raptor says 8 psi intercooled on 93 is fine.
Others , more but not a lot out there documented ...

Last edited by pcampbell; 11-30-2017 at 03:40 PM.
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Old 12-07-2017, 04:45 PM   #4
PA-Outback2000
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7psi is the safe amount with 93. no need to change anything. bring it to a tuner who know how to tune so you don't blow it up.
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Old 05-15-2018, 07:59 PM   #5
pcampbell
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I have been running 10 psi for a while now, no problems.
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Old 05-17-2018, 04:52 AM   #6
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Quote:
Originally Posted by pcampbell View Post
Anyone tried pushing an EJ253 to say 10 or 11 psi or so with 100 octane gas or E85...
These guys seem to think it'll hold/

http://www.cgperformance.com/subaru_turn-key_motors.htm

I was thinking of this as an interim to 257 block which I'm not quite ready for...
if you are using a 257 you should be fine. I dont think you need the 100 octane if you are using the stock 8 to 1 pistons
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Old 05-17-2018, 07:49 AM   #7
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send it
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Old 05-17-2018, 02:00 PM   #8
pcampbell
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Bone stock 200k mile old EJ253.

Right now I'm running 10 psi with 93+torco and a very conservative street tune. It is not even close to detonating - I am sure it has quite a bit more in it , and noticeably more power than 7 psi on 93. I will plan on switching to 93+meth when I get some better gauges installed, maybe exhaust, I am not sure.

Note this is a centrifugal supercharger not turbo, so the boost is high up, I think it is quite a bit easier on the motor than turbo with say 5 psi at like 3000 rpm. I don't hit 5 psi until 4500 rpm.

All the sandrail guys say you can do 10 psi on a stock 253 with race gas, but that is a turbo, not centrifugal supercharger. So I figure 10psi with 93+meth and a centri will be fine all day. It might even be good for 11psi @ ~6400rpm.

Last edited by pcampbell; 05-17-2018 at 02:15 PM.
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Old 11-10-2018, 10:12 PM   #9
pcampbell
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Default 253 with 100 octane

Now running 93 plus water meth. With 11 plus psi from raptor SC hitting 300 g/s and maxing out 565 cc injectors. Iím thinking 300 whp is achievable . Some more tuning them will dyno it.

What injectors should I go with to get my duty cycle back to say 80% so I have some room to grow?

Last edited by pcampbell; 11-11-2018 at 07:34 AM.
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Old 11-11-2018, 08:20 PM   #10
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Quote:
Originally Posted by pcampbell View Post
I decided I want to bump up the boost on stock motor for now. If that means only 8 psi that is OK, but I think we can go higher with more octane to prevent detonation.
Raptor says 8 psi intercooled on 93 is fine.
Others , more but not a lot out there documented ...
yeah but what about the ringlands
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Old 11-12-2018, 07:43 AM   #11
pcampbell
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Default 253 with 100 octane

No problems so far. 185 psi compression on 4 Cylinders. 4% leakdown. Btw motor is 200,000 miles old. Burns lots of oil though.

I am running water meth and I think that is the key. If we had Lower CR pistons we could run some more timing. I havenít been on dyno since 6 psi.

If I were to rebuild Iím not sure what I would do. The obvious choice would just be sti rods and pistons, Lower CR and run more timing. I donít know if that gets me any more power than I have now. I suppose it gives me the option to run more boost.

If I rebuild Iím going for 400whp lol.

Last edited by pcampbell; 11-12-2018 at 07:53 AM.
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