Rb25/26 Serious Issues - Help/opinions

[Shockster0429]

I'm going to really need some ideas on this post here guys. This issue has completely bewildered both myself and my tuner. I cannot for the life of me figure out this problem.

My engine has repeated its almost same exact destruction as it did last year. Melted pistons on intake side, melted quench wells on my head past the fire ring, this time with a blown HG as well as very scored cylinder walls. This is bad VERY bad.

Old threads on the issue

http://www.skylinesaustralia.com/forums/Me...-S-t232311.html

http://www.skylinesaustralia.com/forums/Blow-By-t222021.html

Here is the worst. I have pictures of the damage as well as of my maps.

Main Setup

Rb25 with 26 crank, rods, 87mm wiesco pistons. 9:1 compression.

67mm Precision Turbo, .68 a/r exhaust.

740cc injectors, Dual pumps one 255 walbro and one 044 bosch. Running into a Y right before my fuel rail.

ECU microtech lt12s

Rotella T 15w40 oil used

BCPR7ES plugs gapped to .8mm

Dyno runs.

2 seperate widebands hooked up to my car. Both within .1 -.2 of another.

a/f's 11.2-11.6 from 1-2 psi to full boost.

boost pressure at 13 psi

pump gas 93 octane

timing set at 15 base ramping up to 22 max then backing down to 16 degrees fullboost. (13psi)

engine made no physical signs of issues besides starting to push coolant out, and slowly raising coolant temps.

Car made 380hp@6500 13psi boost first pull, then slowly HP started to fall off and engine began pushing out coolant. Engine had about 500 miles on it

Dyno Vid of the pull

These values are SO damn conservative it isn't even funny. But yet I a destroyed block for the second time now. Both times the damage is pointing to a lean condition/advanced timing issue. However with the values I have listed everything at this engine isnt even flexing its muscles.

Thoughts on this? I was just on the phone with my tuner for an hour. We are both engineers, he is an Aerospace Engineer, but also does cylinder head development and has tuned some crazy fast DSMs. We have talked and came to no solid solution or explanation for this event to have occurred.

Possible thoughts I have.

Bad CAS - from what I have read in the past a bad CAS generally just doesn't work, and if it does work the car runs like a POS, I have never come across an instance where a nissan one was bad, but still allowed the engine to run, and run pretty damn well. Is there ANY reason for my CAS to be occasionally sending wrong voltage/resistance outputs to my ECU telling it the engine is at a time that it really is not? So instead of being at 20 degrees its telling my ECU to be at like 30 or 40 degrees?

-boiling my fuel? (not sure if this could case this issue) The 255 pump uses standard feed, the 044 uses 3/8" line, the both Y together before the rail through a -6an line, then out into a -6an line into my FPR, then back into my stock return line to tank. Maybe this extra fuel temperature is enough for it to pre-ignite? If this is even a possible reason....

-thoughts/input on this id like to hear or see a situation where this has happened.

I cannot see how it would be my fueling since we have 2 separate widebands spitting out basically the same identical values.

This whole situation sucks big time, this final blow has been the worst by far.

Here are pictures and my ECU maps.

-thanks ahead of time for any input.

[zebra]

What intake manifold are you using?

[MrStabby]

So is that damage due to just two dyno runs? ie you were running it in on the dyno?

How did it sound? With that much damage i imagine it would have been rattling its head off with detonation, but could you hear that?

Have you double checked static compression? (IIRC the other thread states 8.5)

Has your builder/tuner done a lot of RBs?

[R31Nismoid]

Just because the AFR's are rich-ish, doesnt mean a thing

1) What intake manifold?

2) Injectors - what brand? Are they hi-flows?

a) Have they been flow tested

b) Have they been spray pattern tested

3) The fuel pump setup - honestly sounds like an abortion. Forget boiling of the fuel, thats not going to happen. To heat the fuel enough you'd need to be running the pumps for hours. I think for starters you should go back to a factory regulator, stock lines, single pump.

a) What is the fuel pressure like?

b) Have the pumps been independantly flow tested from one another?

4) As others have said... detonation... how on earth is it being tuned? Are you listening with 'ears' or whatever to ensure you cant here it knocking its brains out?

As stated on your other thread by RPMGTR...

"Super super conservative"

Um no.....you have detonated it to death.........

See the pic with the side of the piston eaten away....det does that, and yes generally on the intake side.

16 degs (altho it may sound low) can be way too much sometimes, it all depends on the individual engine/setup.

Some combos only cop single digits, while others love 25+…"

I think you've taken little of the advice or looked into the problems if its happened again

FYI - RPMGTR is one of the best builders for RB's in Australia - Ben speaks nothing but the truth.

Out of interest - have you done anything apart from build a new motor and installed it? Ie - ANY checking of parts, tune, and listening for detonation???

Sounds to me like you've done nothing...

[cactus]

380rwhp using 93 octane fuel ... wouldnt help your cause. My old RB20 used to ping its head off when I went from 98 - 95, but I guess if its tuned with 93 it might not be such a bid deal?

[blind_elk]

Bad CAS - from what I have read in the past a bad CAS generally just doesn't work, and if it does work the car runs like a POS, I have never come across an instance where a nissan one was bad, but still allowed the engine to run, and run pretty damn well. Is there ANY reason for my CAS to be occasionally sending wrong voltage/resistance outputs to my ECU telling it the engine is at a time that it really is not? So instead of being at 20 degrees its telling my ECU to be at like 30 or 40 degrees?

The CAS basically tells the ECU where #1 piston is - it doesn't send any particular voltage/resistance.

Have you cheked the valve stem seals. If you ingest oil, you will lower the effective octane rating, which will lead to detonation.

Using 93 octane, I'm guessing you are in N America. Otherwise 93 is waaayy too low.

[djr81]

Looking at the first photo (ie motor with head off) it would appear that all of the cylinders were affected. Which pretty muchs rules out a single dud injector or poor air distribution through the manifold.

[R31Nismoid]

I was thinking much the same

But then looked at a past thread where i think it was #6 only.

So the tune/setup/problem is appearing to be worse than previous... im just trying to cover all bases as it seems its just a case of bolt new motor together, check nothing, boom problem is even bigger

[Swiper the Fox]

looks to me like excessive timing at peak torque while using 93 unleaded.

[Shockster0429]

What intake manifold are you using?

CPC intake with 90mm Q45TB

So is that damage due to just two dyno runs? ie you were running it in on the dyno?

How did it sound? With that much damage i imagine it would have been rattling its head off with detonation, but could you hear that?

Have you double checked static compression? (IIRC the other thread states 8.5)

Has your builder/tuner done a lot of RBs?

Damage was done over the course of 4-5 pulls, it was steady state tuned till in 500-1000 rpm increments to 5000 rpms before this however.

Compression is 9:1 due to my head having to be shave quite a bit to clear up my old damage quench wells. I have quad-dropple checked this.

Listen to the video you hear nothing out of the ordinary, granted the car is very loud, there's no breaking up, no audible detonation.

No one does RB's anywhere near my location. Local engine builder builds V8's mainly, I do not think this is a mechanical issue.

Tuner firs time working with an RB, he has tuned plenty of v8's and 4g63's, very knowledgeable guy.

Just because the AFR's are rich-ish, doesnt mean a thing

1) What intake manifold?

2) Injectors - what brand? Are they hi-flows?

a) Have they been flow tested

b) Have they been spray pattern tested

3) The fuel pump setup - honestly sounds like an abortion. Forget boiling of the fuel, thats not going to happen. To heat the fuel enough you'd need to be running the pumps for hours. I think for starters you should go back to a factory regulator, stock lines, single pump.

a) What is the fuel pressure like?

b) Have the pumps been independantly flow tested from one another?

4) As others have said... detonation... how on earth is it being tuned? Are you listening with 'ears' or whatever to ensure you cant here it knocking its brains out?

As stated on your other thread by RPMGTR...

I think you've taken little of the advice or looked into the problems if its happened again

FYI - RPMGTR is one of the best builders for RB's in Australia - Ben speaks nothing but the truth.

Out of interest - have you done anything apart from build a new motor and installed it? Ie - ANY checking of parts, tune, and listening for detonation???

Sounds to me like you've done nothing...

Injectors have been flow tested I have the charts somewhere in my room, they are all within 2% of another.

Factory regulator wouldn't handle the flow of the new setup, How does it look like an abortion? I wanted to be safe for fuel on the dyno and not max my walbro out if the car made what it should have made. It was a safety thing. Using an Aeromotive 1000 reg, all steel braided lines, welded a -6an fitting to my stock rail to eliminate hoses. Running a dry FP gage for accurate readings. Static pressure was set to 45 psi, reg was working properly.

Last time the engine did this it was attributed to super high EGT's when my exhaust cam gear was rotated completely clockwise and driven on for a few weeks before discovering where my HP was going. (very embarrassing to say the least, however it was missed by over a dozen mechanics/car knowledgeable car enthusiasts, two of which were my old tuners)

Fresh build the bears were all changed out, although the old ones were still okay.

380rwhp using 93 octane fuel ... wouldnt help your cause. My old RB20 used to ping its head off when I went from 98 - 95, but I guess if its tuned with 93 it might not be such a bid deal?

People make high 500 hp through 2.0 liters on our 93 octane, 2jz's have made over 600 on 93 ocatane, a few RB's have made over 500 on 93. I don't see how how an build RB cannot if this is the case.

Also the microtech static timing is 15 degrees, now are you suggesting this value be changed to say 10 degrees or even 5 degrees so that we can retard to such a state? 15-16 degrees full boost at 13 psi just seems very conservative for a fat bore very short stroke motor. You could be right though, maybe it is on pump gas?

I was thinking much the same

But then looked at a past thread where i think it was #6 only.

So the tune/setup/problem is appearing to be worse than previous... im just trying to cover all bases as it seems its just a case of bolt new motor together, check nothing, boom problem is even bigger

Last destruction was all cylinders the first one looked the best. But I have 6 melted 700 mile JE pistons from the first time.

We checked plenty mechanically, new tuner this time as well.

What else would you have checked? Please enlighten me. The car was ran over for any leaks, everything was torqued properly, cams were at factory 0 degree setting base, ring gaps were not aligned, head was completely redone as far as valve seals and proper flatness/roughness, as well as the block. New bearings, new head gasket, new steel braided fuel lines.

Engine pic.

looks to me like excessive timing at peak torque while using 93 unleaded.

Peak torque was around 290 ish ftlbs at 6000 rpms. So timing at this point was 16 degrees.

Does anyone have a similar octane map with a decently large turbo on an RB motor? I'd really like too look at one.

I have a few details on a states rb20 build with a 30r, hes running 20-21 degrees advanced at 21-22 psi through it making 400whp on pump 93 American octane without issues.

I appreciate the responses thus far.

Anymore insight on the standard Nissan CAS? I saw the above post, I know it reads the #1 cylinders location, however its still sending a voltage/resistance signal (not sure of how Nissan has it setup internally) to the ECU, its not a mechanical signal...

[Tangles]

using the same head as before? same bottom end as before?

Id be using a totally new engine setup, different bottom end and head from a RB, rebuild it all again.

massive detonation going on.

93 ron fuel - do you have higher ron fuel available, or additives? 93r on a RB is a bit low, easier for the engine to detonate.

fuel delivery isnt right, somewhere. redo the lines as a single unit one fuel pump (bosch), use a nismo fpr if need be (NOT rising rate fpr)

bad bad luck. best of luck with the next project build. hope you are using a manual and setting the right tolerances for bolts etc.

[R31Nismoid]

Factory regulator wouldn't handle the flow of the new setup,

Sorry mate but that's just rubbish.

I went 370rwkw stock RB25 reg, i know MANY MANY a RB26 that has done near on 400rwkw, again stock reg

anyway...

As for the abortion part - i meant your entire fuel setup. Why have you modified so much, when all the factory gear (save for fuel pump and wiring) is beyond adequate...

Anyhow - you missed a few answers to the questions, please go back over them

[Mr. Oizo]

Guys, he is in America,

They use a different octane rating (AKI or PON)

USA 93 Octane is equivalent to our 98 Octane (MON)

[Shockster0429]

Just because the AFR's are rich-ish, doesnt mean a thing

1) What intake manifold?

2) Injectors - what brand? Are they hi-flows?

a) Have they been flow tested

b) Have they been spray pattern tested

3) The fuel pump setup - honestly sounds like an abortion. Forget boiling of the fuel, thats not going to happen. To heat the fuel enough you'd need to be running the pumps for hours. I think for starters you should go back to a factory regulator, stock lines, single pump.

a) What is the fuel pressure like?

b) Have the pumps been independantly flow tested from one another?

4) As others have said... detonation... how on earth is it being tuned? Are you listening with 'ears' or whatever to ensure you cant here it knocking its brains out?

As stated on your other thread by RPMGTR...

I think you've taken little of the advice or looked into the problems if its happened again

FYI - RPMGTR is one of the best builders for RB's in Australia - Ben speaks nothing but the truth.

Out of interest - have you done anything apart from build a new motor and installed it? Ie - ANY checking of parts, tune, and listening for detonation???

Sounds to me like you've done nothing...

I'll try to answer you again.

1. Manifold is a CPC Plenum from Ariel Banco. Stock flange/runners, new plenum, stacks and Q45 TB.

2. Injectors are 740cc's from Deautchwerks (factory modified injectors, all flow tested and spray tested, I have these results from them, these injectors have power high 800-900 hp cars, obviously with a different CC but same setup)

3. a. fuel pressure is 45 psi static vac off, ramping up one PSI per lb of boost. So was maxing at 57-58 psi.

b. no the pumps havent been tested independently. The 044 is 1200-1300 miles new, the walbro 255 is about 12,000 miles old.

This fuel system is not in series, its in parallel the pumps have separate lines and filters until right before the fuel rail. I wanted to run a dual feed rail with a middle return however to my knowledge there isn't one made to support factory style side feed injectors that I run.

When using this setup above with the nismo reg and not the A1000 reg, the nismo unit was not allowing the FP to rise properly and the fuel was off the map (engine was heading lean), it might been a faulty unit or it might not have been able to handle the flow of both pumps. The A1000 was put into place for the unit and that was the END of my fuel pressure problems. This was done last year while on tuning on the dyno.

4. There is no knock device on the ECU, Microtechs have never run them since they have been in existence. People have pumped out big power with this ECU w/o knock detection. From what I understand with aftermarket knock detectors half of them do not even work since they are detecting valve train noise, regular engine noise, injectors, open wastegate w/e it might be and not providing accurate knock detection. This motor sounded completely normal and healthy, there was no audible sound coming from it to draw any type of alarm.

The owner of the shop we are at builds 1000 hp high compression n/a v8's, he even stated how well the car sounded and how he heard no knocking. We pulled plugs and they looked okay. There was really no sign of detonation them them at all. I can post pics if you need me too.

Is there a reason for this? On our rb25 motors do the intake side quench wells on the head absorb all this energy and hide plug readings? If that is the case it makes a lot more sense to why the plugs werent showing a significantly bad problem.

using the same head as before? same bottom end as before?

Id be using a totally new engine setup, different bottom end and head from a RB, rebuild it all again.

massive detonation going on.

93 ron fuel - do you have higher ron fuel available, or additives? 93r on a RB is a bit low, easier for the engine to detonate.

fuel delivery isnt right, somewhere. redo the lines as a single unit one fuel pump (bosch), use a nismo fpr if need be (NOT rising rate fpr)

bad bad luck. best of luck with the next project build. hope you are using a manual and setting the right tolerances for bolts etc.

The head was the same as last years, just fixed and decked properly. The block was re-honed from last time for it wasnt damaged. This time I will need a new head for sure, and possible a new block.

As stated below our 93 octane is equivalent to your 98ron

Why do you suggest redoing the line into just one? To simply eliminate a possible issue? Cant go back to the nismo if I did this it would be with the A1000 which is a proven fuel pressure regulator.

I have the complete UK 7XX page manual for the R33 engines, I use it EVERY time I'm working on a anything engine. Items are torqued to specs noted in the manual for everything.

Thanks for the luck, I have no plans to rebuild until I've pinpointed the issue.

Sorry mate but that's just rubbish.

I went 370rwkw stock RB25 reg, i know MANY MANY a RB26 that has done near on 400rwkw, again stock reg

anyway...

As for the abortion part - i meant your entire fuel setup. Why have you modified so much, when all the factory gear (save for fuel pump and wiring) is beyond adequate...

Anyhow - you missed a few answers to the questions, please go back over them

Modified because the 255 pump will be on its max for the HP we were looking to get. They are only safely good for low 400's on their own. Sure people have gotten over 500whp with a single 255 pump with a rewire and 14-14.5 volts, but theres no need to take that risk. The 240sx has very limited options with fuel, the 044 is simply easier to mount outside the car instead of trying to jam into the factory tank. So I ran them in parallel and with a larger return this setup and a dual feed rail this should be good for 700 plus HP.

My pumps have been rewired as well and are seeing 14.0 volts. +-.2

Guys, he is in America,

They use a different octane rating (AKI or PON)

USA 93 Octane is equivalent to out 98 Octane (MON)

thank you for stating that for me.

Any ideas on the Mircotech unit itself displaying false readings? Or receiving the right signal from the CAS but executing the wrong timing for the engine? The ECU is throwing no codes, and seems to be working properly. Just another thought on the issue...

thank you everyone for replying and trying to help locate the exact case.

[FineLine]

That my friend is timing detonation. If you rebuild the same or similar setup use a thicker head gasket and get your cr down around 8.5 to 1.

My engine initially ran this cr and begged for more timing right up to around 25 degree.

Spat a welsh plug and warped the head slightly so we faced it and reassembled using the same thickness gasket which took cr to around 9 to 1 and the engine was knocking stupid at 15/16 degrees.

Replaced the gasket with a thicker one to get compression back to where it was and problem solved.

I was surprised at how much timing adjustment was required to prevent detonation going from 8.5 to 9 to 1 cr.

[Shockster0429]

That my friend is timing detonation. If you rebuild the same or similar setup use a thicker head gasket and get your cr down around 8.5 to 1.

My engine initially ran this cr and begged for more timing right up to around 25 degree.

Spat a welsh plug and warped the head slightly so we faced it and reassembled using the same thickness gasket which took cr to around 9 to 1 and the engine was knocking stupid at 15/16 degrees.

Replaced the gasket with a thicker one to get compression back to where it was and problem solved.

I was surprised at how much timing adjustment was required to prevent detonation going from 8.5 to 9 to 1 cr.

Interesting info, the first time. (last year when this same issue occured) The CR was 8.5:1 since the deck required a good deal of shaving to clean up my quench wells I went with a 1.5mm gasket to allow it to be at 9.0:1 compression.

Last year when the car did the same thing the timing was the same as it was now. 15-16 degrees@ full boost which includes peak torque.

Question would be now last years destruction be caused from running on a maxed retarded exhaust cam gear for a few hundred miles with crazy high EGT's or was it caused after I fixed the cam gear back to the zero position? At this time the compression was 8.5:1.

[psi]

interesting...

My freind bought his Skyline with a busted RB25 in it. We swapped it and I pulled the old unit apart. It looks the same as your engine..

Our busted engine was a complete stock engine, intercooler was stock, injectors, ecu.. the works.

I know that our busted engine was running very high boost with no mapping or anything else to support it. every piston is busted and all the damage in ours looks the same as yours.

My point: we all know that the standard ecu pumps WAY too much fuel into the engine at high boost, and the timing is very aggressive.

Our engine would have also been suffering from very high intake temps from the standard intercooler. Goodness only knows if the old owner even checked water and oil temps!

Apart from all the melting in the top end.. the rings were still complete and unbroken, bearings looked good and all else appeared fine.

I think fineline has pinned this one down for you...

[Wheezy]

Perhaps look into something like this next time: http://www.gizzmoelectronics.com/Product_KMON.html

You stated you were driving around last time with extermely high EGT's yet you kept on driving???? WTF?

You also stated that your tuners do not know RB's, and let them tune it like a carby V8. No care taken, but a little ignorance on both their \ your part.

Not trying have a personal attack here, it just sucks that you have had to learn for a 2nd time.

I would be looking at getting a new RB25 and a tuner that takes more care than this.

[blind_elk]

The Microtech is fully programmable. Have you actually checked the base (idle) timing with a timing light? Does the Microtech have a timing trigger offset setting?

Peak torque was around 290 ish ftlbs at 6000 rpms. So timing at this point was 16 degrees.

I have a RB25 running off a Wolf 3D, it's pretty stock (around 12psi) , but at full noise @6000, it runs around 8 degrees timing.

[Shockster0429]

Perhaps look into something like this next time: http://www.gizzmoelectronics.com/Product_KMON.html

You stated you were driving around last time with extermely high EGT's yet you kept on driving???? WTF?

You also stated that your tuners do not know RB's, and let them tune it like a carby V8. No care taken, but a little ignorance on both their \ your part.

Not trying have a personal attack here, it just sucks that you have had to learn for a 2nd time.

I would be looking at getting a new RB25 and a tuner that takes more care than this.

Thats not to case, EGT's were slightly ignorance, I do not have an EGT gauge, at the time it was driving tuners thought it was loosing power due to head issues, valve float. Not due to the fact my exhaust cam gear was clocked completel retarded. Its not easy to see this at a glance due to the CAS covering the gear. Turns out that might have not even been then issue, that's just speculation to a possibility to the engine dieing.

Tuner is VERY careful I just gave you all the maps, and a/f's in which the engine was running. You make is sound like we were just beating on this engine like a bunch of apes with no care that is totally not what was happening.

There is so much mismatch/incomplete information out there. I search this site for Microtech issues and all I see is majority of people just bashing it giving no solid explanation to reasons they do not like it. When no one really addresses CAS issues with other EMS's. I know AEM had to make their own trigger wheel to fix the issues they had with the nissan OEM CAS. People have had problems getting their Haltechs to work properly with the OEM CAS.

From more research this afternoon this is looking like a CAS/trigger wheel issue.

Do please read the last page or so of this thread. Also read the following link as well to a modification to the RB CAS with a Z31 wheel.

http://forums.nicoclub.com/zerothread?id=325824&page=9

http://forums.hybridz.org/showthread.php?t...p;highlight=cas

It seems that the stock CAS for aftermarket ECU's can cause timing issues, some cases are more severe than others. But from this information it seems that the varying windows on the trigger wheel at high RPM cause issues for the ECU to read properly causing improper timing that go unseen while logging/monitoring.

Food for thought but I'm starting to feel with a proper trigger wheel, with a non varying trigger wheel opening might solve this problem.