new turbo, should i rebuild?

[90240sxca18]

so i compression tested my motor when it was out of my car

#1-140#2-135#3-135#4-145#5-135#6-140

the motor in my car ran extremely rich. it was stock rb20 with rb25 turbo, untuned. ran rich as ****t!! black smoke stained on the walls in the shop, fireballs all the time. completely black sparkplugs.. shooting liguid out the exhaust. with previous owner on a tune with a safc it made 232whp n 216 lb-ft of torque.

yesterday i trade my rb25 turbo, stock manifold, smic,intake manifold. for a top mount xs power manifold with a t3 flange, hks fmic with piping, log intake plenum manifold, sc61 precession turbo, and a safc. i was wonder if my rings possible shoudl be replaced or should i do a rebuild before i put the turbo on n run 12lbs 280 whp + i was juts going to order arp headstuds and a head gasket and rb26 cams. but people on my local forum said that the rings are about to go and i need a rebuild.. hellppp

[kumasan616]

compression is just a hair on the low side, but not bad at all. Does it blow blue smoke when running? if not, rings might be okay, it could be valve seals starting to let go. Then again, in addition to the new rings you should buy new bearings/seals and get the block align/honed/cleaned. Or, if you don't care about all that, just slap a new HG with new HW and run it until it lets go. Its your call...
Modified by kumasan616 at 8:11 PM 1/13/2009

[WhatsADSM]

You compression checked it with it out of the car? Those numbers look actually pretty good then. You were supposed to do the compression check with the throttle WOT and the engine up to normal temp. Which would bump those numbers up quite a bit.

So..... "if it ain't broke don't fix it". Spend your money on something else.

[BoostFab]

so i compression tested my motor when it was out of my car

#1-140#2-135#3-135#4-145#5-135#6-140

the motor in my car ran extremely rich. it was stock rb20 with rb25 turbo, untuned. ran rich as ****t!! black smoke stained on the walls in the shop, fireballs all the time. completely black sparkplugs.. shooting liguid out the exhaust. with previous owner on a tune with a safc it made 232whp n 216 lb-ft of torque.

yesterday i trade my rb25 turbo, stock manifold, smic,intake manifold. for a top mount xs power manifold with a t3 flange, hks fmic with piping, log intake plenum manifold, sc61 precession turbo, and a safc. i was wonder if my rings possible shoudl be replaced or should i do a rebuild before i put the turbo on n run 12lbs 280 whp + i was juts going to order arp headstuds and a head gasket and rb26 cams. but people on my local forum said that the rings are about to go and i need a rebuild.. hellppp

you are more concern when there's a drastic difference between the cylinders. but yours are pretty even on all 6, so wouldn't worry about a rebuild. are you still running on the stock headgasket? some aftermarket headgasket will lower your base/static compression.

it is proper to run the engine to operating temperature, and then do the compression test while WOT

[Neejay]

Cullen, I didn't know the test was done out of the car. lol

I'd say the engine is fine then. Those numbers would probably be at least 150 if it were warmed up + WOT.

[Darius]

Sounds like a horribly rich tune to me...

[90240sxca18]

Cullen, I didn't know the test was done out of the car. lol

I'd say the engine is fine then. Those numbers would probably be at least 150 if it were warmed up + WOT.

whats the difference with it being out of the car? i dont recall blue smoke. maybe at idle a little. i just dont want to put this turbo on, get a smaller wastegate spring and set it to 7lbs n then blow the motor while its getting tuned. its my daily driver and hafta have it back on the road by saturday at midnight. one of the guys at the shop says my rings are fine and everyones an idiot for assuming without a leakdown test. i really just dont want to blow it, and run it at 250 hp for as long as possible. so no rings n rebuild should be needed? yes compression test was without the car being warmed up, and no throttle.