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Boost Junkie
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12,613 Posts
Discussion Starter #1
I am having smoking problems that I attributed to my 2nd turbo being on the outs, but just to make sure we did a compression test tonight. Here were the results-2 high, 1 low, 3 medium:

1-178
2-150
3-170
4-165
5-162
6-180

Obviously 1 and 6 have a lot of carbon build up for some reason. 2-5 look okay, other then 2 being a little lower then I would like. My Supra has 103k miles on the clock and is BPU+++++. I have an SP63 kit, BL fuel system and built tranny just waiting to be put on. Now that my 2nd turbo is officially on the way out, it will be going on very soon.

Let me know what you think!

Steve K.
 

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Old School
Joined
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4,051 Posts
I think 30 psi difference from low to high would concern me. I'd also likely just live with it.

You might try a top end cleaner like GM or Mopar makes. You could also try Rislone or Auto RX to see if you could free up sticking rings.
 

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Boost Junkie
Joined
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12,613 Posts
Discussion Starter #3
Yes,

The 30psi difference is interesting, but I attribute it to the carbon build up mostly. I know that previous owners ran dyno oil and I run synthetic. I just changed the oil, but next time I may try the Rislone product to see if it helps. I guess considering I have only owned the car for the last 6000 miles, I can't get too upset. Hopefully the motor will last a bit longer. It did make great power last time out-425whp at only BPU+ through an automatic so it isn't hurting me too badly.

Steve K.
 

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Republican
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8,421 Posts
I dont know... 30 PSI is ALLOT. max variation is what... 14 psi? your 2 times the amount... i'd say your haveing some problems
 

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Shawn Davis
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1,662 Posts
I'd agree. You've got issues. Try doing a few top end runs (up hill if you can) to burn off any carbon and repeat the test. You might also want to run a leakdown test to see how that turns out.
 

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Will work for Supra parts
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624 Posts
I don't know, maybe it's me, but the 150 psi along with the 162 and 165 psi aren't so far out of line. Those numbers sound pretty normal. The carbon build up I might be concerned with, but when you consider your dyno results, I'd say you've got a pretty healthy engine there.
 

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Supra TT Senior
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1,887 Posts
All numbers are where they should be but the variance is way off. The max difference should be 15psi I believe. I just had my car tested about 2 weeks ago and it came out with a 5psi difference between low and high numbers.
 

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Boost Junkie
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12,613 Posts
Discussion Starter #8
Thanks guys,

I have some Torco additive in there and it was all over the pistons/sparkplugs. Not sure if that would make a difference or not, but I am going to run a full tank of good unleaded race gas through it, try that combustion chamber cleaner-since a couple of them are nasty, and see what I get. If I am not happy then I'll also try that Rislone additive when I change the oil next time. The car does make great power though-so I'll need to test this several times.... don't really want to spend the bux on a new short block just yet. I'll report back with my findings. This is the first time I've done a compression check so I am just getting into this.

Thanks for the replies.

Steve K.
 

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Super Moderator
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10,496 Posts
Evill Supra said:
Thanks guys,

I have some Torco additive in there and it was all over the pistons/sparkplugs. Not sure if that would make a difference or not, but I am going to run a full tank of good unleaded race gas through it, try that combustion chamber cleaner-since a couple of them are nasty, and see what I get. If I am not happy then I'll also try that Rislone additive when I change the oil next time. The car does make great power though-so I'll need to test this several times.... don't really want to spend the bux on a new short block just yet. I'll report back with my findings. This is the first time I've done a compression check so I am just getting into this.

Thanks for the replies.

Steve K.
Steve K.,

Your approach is the smart one. I don't think you have a problem and you won't know for sure if you do until you decarbonize (is that a word?) that thing and clean her up but good. I'm guessing you'll be okay after all is said and done.

P.S. When you get her all cleaned up, I'd include a leakdown test along with the compression check to eliminate any questions whatsoever. Good luck.

Ken.
 

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Banned
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3,794 Posts
those numbers are just fine, other than the carbon buildup. easiest/cheapest way to clean it up is to run water through the engine, just a MIST of water, kind of like alcohol injection.
 

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Boost Junkie
Joined
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12,613 Posts
Discussion Starter #11
Well fellas,

I think I jumped the gun a bit-perhaps out of worry. I took the car to the dyno today and made 417whp at just 19psi peak. Last time out it made 424whp at 23psi peak. Only changes were that I added the VPC and switched from the Thermal exhaust to the Boostlogic. To make nearly the same power, with 4 lbs less boost is good if you ask me. It was 85 degrees out today and I could only make 19psi due to my stock twins getting so weak. Last time out it was 65 degrees. Now-I'm going to redo the compression test later in the week and do a full leak down as well. After seeing today's numbers I think I am fine, but you can never be too safe.

Thanks for everyone's help and input.

Steve K.
 

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Registered
Joined
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294 Posts
Might try this too....

I believe Chevron Techron Concentrate would help you with the carbon issues. Just be sure to buy only the Techron, not the fuel system cleaner that is a blend of Techron and some other stuff.

Hope this helps.

Later,
 

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(overspooled)
Joined
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2,836 Posts
Evill Supra said:
Thanks guys,

I have some Torco additive in there and it was all over the pistons/sparkplugs. Not sure if that would make a difference or not, but I am going to run a full tank of good unleaded race gas through it, try that combustion chamber cleaner-since a couple of them are nasty, and see what I get. If I am not happy then I'll also try that Rislone additive when I change the oil next time. The car does make great power though-so I'll need to test this several times.... don't really want to spend the bux on a new short block just yet. I'll report back with my findings. This is the first time I've done a compression check so I am just getting into this.

Thanks for the replies.

Steve K.
30 psi could be difference between a cold test and a hot test.. Was the engine warm when you did the test? Those dyno numbers kinda say that things are good, ussually when things are about to go tits you'd see low compression not necessarily high...but :dunno: I just did one a couple weeks ago and had 161 to 169...
 
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