hybrid901

I did a compression test a few days ago and my numbers were roughly 1 thru 4 185, 170, 170, 130 so we did a leak down test tonight. With a 100 psi pressure I had 93, 93, 90, 39. I have no idea how long its been low since this is my first leak down ever and first compression test in about 6 months. It might have something to do with me driving on 14+ psi everyday. I'll be going to the track tuesday to see if my mph has dropped since my last run 2 weeks ago.

B20LS-T

does the car feel any different? slower? Is this on a stock motor or built up?

hybrid901

It doesn't feel any slower to me but I'll see what my mph is at the track. Its on a b18c1 with 9:5:1 srp's.

boostaholic

If your numbers are correct then your number 4 piston rings are probably toast. Is your car burning any oil?

hybrid901

It will smoke a slight bit at full boost. I might go through a qt every 3000 miles. It is the ring. I'm hoping I can just drive it until I finish my other motor.

hybrid901

up

hatchy

You should be fine if you take it easy on your car. It'll just burn a little oil and smoke a little.

abid@sfp

I know exactly what's wrong. The SRP's are not designed for anything above 10psi. They are made of a high silicone base material which compresses the ring lands at anything above 10psi. Out of all the turbocharged engines we've built everyone that had SRP's always compressed after 10psi, this is why we no longer use them. I spoke to a tech at JE and he even said that those pistons are not designed for that kind of boost because of the material they're made from. You're much better of spending an extra $100 bucks, and going the JE route. Hope that helps.

abid@sfp.net
(Tech Dept)

hybrid901

Damn that sucks I ran 10psi on the stock pistons without ever having a problem. Do any other pistons besides the SRP's have this problem? JE, Weisco, Ross, Aries?

CovertFI

do you have alot of blow by?

abid@sfp

To be honest with you, once we had that problem with the SRP's, we just switched over to the JE's and we've never had a problem since. Wiseco is also a good piston, nothing like an SRP.

abid@sfp.net
Tech Dept

ion_four

I'm not completely up on my metallurgy, but how would the piston have a high content of silicone? Or do you mean something else?

abid@sfp

The SRP is made of a 4032 alloy which is made of a high silicone base. This keeps the piston from having a high threshold for boost, approximately 10psi limit before the ring lands begin to compress. These pistons are fine for naturally aspirated road race applications and maybe even a descent amount of nos such as about a 100hp shot, but that's about it. Hope that helps shed a little light on the subject.

abid@sfp.net
Tech Dept

hybrid901

I went to the track last night and never got a clean run but my best mph was 113.7. The weather was a little worse that my runs at 115.5 but I was suprised that my mph didn't fall off more than this with my shitty compression/leak down #'s.

memphiss13

the run where the boost pipe came off looked like it was going to be an 11 sec run. it seemed like you got off the line really good. maybe next time.

hybrid901

Yeah my 1/8 time was .38 faster than my 12.3 run. It felt like I ran into a wall when the pipe blew off.

memphiss13

it looked like it, the car lunged forward when it lost power like you just lifted the gas or something