Rb25 help!

[josh350gt]

I have a 93 sil80 with a rb25 several bolton mods.
Issue: this is the second rb25 that ive had the EXACT same issue with.
Problem is ring failure in the #5 and or #6 piston Combined with turbo seal failure BOTH times.

i KNow that RB 20/25 have weak ring lands and i konw that the stock t28 turbos are crap, but what are the chances that the same thing happens 2 times on 2 different motors?

I recently bought another rb25 complete bottom end and decided i would replace the rings and bearings and install it. i have yet to coplete the bottom end when i found that i am plagued with a blown turbo seal AGAIN as well. i never run the turbo over 13 pounds.

i plan to go with a top mounted gt35 turbo and 550cc or 770cc injectors.

i have an AEM afr and an apexi safc to tune with.

stock turbo, injectors, and internals what is causing this?!?!?

boltons are greedy intake manifold, q45 Throttle Body, Fuel Pressure Regulator, GTR fmic, greedy bov, hks intake, electric fan, and manual boost controller.

Help me out!

[Yellow4g63]

The 20 doesn't suffer that weakness. Its the piston design on the rb25. You might be running too much timing. Look into some supertech pistons they might be cheaper than cp pistons. Ditch safc and look into a stand alone or a z32 ecu with a nistune board to get better command of your motor.

[josh350gt]

ill check on the timing issue but its the exact same thing on both the motors. i was looking into emanage ultimate. i thought about the nistune but it seemed like too much of a hassle. ive got another full bottom end im replacing the rings and bearings just for now and rebuilding the current bottom end.

[Yellow4g63]

The emange/piggy back systems are more of a hassle because of the wiring. My friends rb25 when it had stock turbo put down 275whp with bolt on parts @ 12psi. We tried more boost but the only gain was down low but no gain up top. It started to run a little lean too.

[josh350gt]

yea, i was only at 13 lbs and with all the mods listed above. i saw a little bit of oil in my bov outlet, could the messed up compression ring cause oil in the bov or is this strictly from a blown turbo seal?

[Yellow4g63]

Originally Posted by josh350gt

yea, i was only at 13 lbs and with all the mods listed above. i saw a little bit of oil in my bov outlet, could the messed up compression ring cause oil in the bov or is this strictly from a blown turbo seal?

Do you have the breather from the valve cover going back into the intake tube on the turbo? If so that will cause oil to get into the bov/intercooler.

[OutToWinPAHC]

shame your so far away I have a healthy short block. But I would want to see your AFR numbers on a dyno under load im not a piggy back fan at all

[mewantkouki]

I think it's time to find the rotating assembly from a rb26... Gotta be cheaper than replacing bottom ends. lol

[josh350gt]

my breather goes out to the catch can and the can is vented to atmosphere instead of recirculated. will an rb26 crank/pistons/rods fit a 25 block?

[Bnr32gtr]

I think its the greddy intake manifold I've seen it a ton of times where cylinders 5 and 6 lean way out because of the manifold! Not say that's what happens just putting it out there I think its a mush to have it tuned per cylinder! Just my 2 cents

[josh350gt]

spend 1300$ on an intake mani just to have it blow up my motors!!!!!!!!! well poop!

[josh350gt]

Originally Posted by mewantkouki

I think it's time to find the rotating assembly from a rb26... Gotta be cheaper than replacing bottom ends. lol

Will it fit the 25 block?

[smoked240]

From what I read the rb26 crank will work in the block but you need the rods also.

[Yellow4g63]

Cheaper to buy another 25 block. Rb parts are gold, so are good rb26 cranks.

[OutToWinPAHC]

Selling a 26 crank, rods, block, head.... lol

[josh350gt]

Originally Posted by OutToWinPAHC

Selling a 26 crank, rods, block, head.... lol

haha well the pistons ringlands are whats bad on the 25 so id need the pistons too. would i be ok with getting the 26 crank and then doing aftermarket 26 rods and pistons?

[zerodameaon]

This is to back up the previous post about emanage being garbage, they are. Buy a proper ECU system or build yourself a Nistune off a Z32 ECU. I had nothing but issues and in the end had to take mine off. As for the ringland issue I still had my stock intake and my ringlands went as well.

[josh350gt]

ok so my plan at the moment is 26 crank, aftermarket 26 rods and pistons........WAIT will a 26 bottom end fit on a 25 head?

[EvilRB]

Yes

The 25 and 26 are basically the same block just a few minor differences

Read this: question rb26 internals into rb25 ??? - GT-R Register - Official Nissan Skyline and GTR Owners Club forum

Do your research but you can do alot and since you have the spare block you can play around with a few different set ups.

Good luck!

[OutToWinPAHC]

Im pretty sure the 26 crank does not fit the 25 block.... fits a 20, they share the same size rod journals but the main journals are different 20/26 to 25. You can put a 25 head on a 26, 26 head on a 25. 26 rods aka 25 neo rods in a 25.

I think what you need is better management and a fresh bottom end. if your on a budget 26 rods in a 25 with forged pistons and call it a day.

[josh350gt]

if i get a 26 bottom end i need bigger injectors. sweet.

[double zero]

so pretty much your turbo killed your engine??

[josh350gt]

Originally Posted by double zero

so pretty much your turbo killed your engine??

i think so, is it possible that a blown turbo seal can cause your compression rings to fail?

[naCAnItIhS]

Shouldn't.. A bad ring land is not the rings themselves going bad its the groove in which they sit that cracks and breaks off. Typically pre-detonation causes this. Timing issues and/or not enough octane in your fuel for the amount of timing you are running.

All a blown turbo seal is going to do is spit excess oil everywhere. (intercooler, intake, etc)

[josh350gt]

Originally Posted by naCAnItIhS

Shouldn't.. A bad ring land is not the rings themselves going bad its the groove in which they sit that cracks and breaks off. Typically pre-detonation causes this. Timing issues and/or not enough octane in your fuel for the amount of timing you are running.

All a blown turbo seal is going to do is spit excess oil everywhere. (intercooler, intake, etc)

i definatly have a blown turbo seal and my compression ring is bad in my #5 because compression is down to 30 lol

[josh350gt]

i always run 93 octane so its got to be a timing issue,causing the engine failure. the car idles super high like 1700-2000 rpm and the afr is all over the place. i blow oil out of the tail pipe and excess out of the bov and in the intercooler and what not. not to mention it smokes like nonstop when in any load at all.