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Discussion Starter #21
You've got room off the front if you need it. You won't want to go too big on the wastegate as that makes it harder to control boost up top. A 60mm is a bad idea. I'd try a single (Tial 46mm would be my choice) and see how it goes. Then add a second one if needed. I'll send you a picture of mine for reference.

Steve
I've decided to go twin 46mm wastegates and will have a new wastegate inlet tube fabricated in the front of my manifold, what spring should I run if I only plan on running 20psi? I was thinking 15psi spring? can you send me pics of your dual setup? thanks
 

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If this is a dynojet then I feel something is wrong. It's' definitely low on power by at least 15% imho. If this was a Mustang dyno or another adjustable dyno then it could be that the dyno reads low. I would verify that everything is mechanically ok, boost leak checks, etc. 6766 at 19psi shouldn't be making that power regardless of compression being stock and it being on pump gas.

It's been a month maybe the OP has since figured it out.
 

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Boost Junkie
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If this is a dynojet then I feel something is wrong. It's' definitely low on power by at least 15% imho. If this was a Mustang dyno or another adjustable dyno then it could be that the dyno reads low. I would verify that everything is mechanically ok, boost leak checks, etc. 6766 at 19psi shouldn't be making that power regardless of compression being stock and it being on pump gas.

It's been a month maybe the OP has since figured it out.
Sure has. Hopefully. To me it looks like massive lag and boost creep.

STeve
 

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adammackintosh.net
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I might also recommend meth injection if you are stuck on 93. I am stuck on 94 up here in Canada because no E85 around here. Meth has been a saving grace allowing me to run 25-29psi with fairly retarded timing, but for me the difference between pump and pump+meth is very significant. I don't run water in mine, just 114 octane methanol which is about $1.60 CAD per litre, and she only takes about 4 litres per month.

I have GSC S2 cams, so perhaps quite similar to your HKS 272s, and my car pulls very hard past 6k. It makes a huge difference in 3rd/4th gear to go from 19 to 25+ PSI at 6k+ RPM (with meth vs. not).

On my car I have two 550ml/min meth nozzles installed around 6" upstream of the throttle body. They work fantastic, but of course there is arguably some risk associated with fogging meth rather than direct port. In practice it works fine on my car, and I would hate to run less than 25psi. My opinion is that 6766 should turn over a brutal hand at 25psi compared to 19.

It's been a few years since I looked at maths here, but I recall the Precision turbos make something like 10hp per 1psi until around 25psi and then they start making 20-40hp per 1psi because it's right in optimal turbine efficiency part of the map.

Also I dunno for sure but I might venture a guess that the 0.84AR hotside is limiting your peak a bit, and I'd be curious to see your seat of the pants observation about how fast it spools because you are probably trading peak power for mid-range power, so the car may put down very good numbers at the 1/4 mile even though it "only has 499whp".
 
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