RB27 Tuning Update! Need Help.... Issues stilll...

[Shocker]

Are those MT drag radials?

Yes sir ET Streets 275/40/17's. Having a little bit of a rub issue since there is not really any negative camber in the rear. The GT-R wheel offsets are a bit to far out for the rear. The car is getting aligned Wednesday.

Carl I'm going to try one last thing tonight, I've got a 1.75" pipe I'm going to weld on instead of the current 1.25" one I believe it is.. its small. TOO small IMO. I feel it might be creating to much back pressure on the gate.(I bought it being ready for use its what the kid welded on) I'll see what that does, my wastegate outlet is basically identical to those who on the 6 boost manifold. In fact my manifold is almost identical to theirs.

If I run out of options I will have to try and recirc to see if that solves my issues.

I appreciate the support, it has been really hard not to quit, but having my car run really puts a smile on my face.

[Darius]

Those are only 9-inch wide wheels, right?

Damn 265/40/18s are going to be stretched on 10's. I'll have to put together a winter project 08-09 thread and post pics of what I've been up to.

[Shocker]

Those are only 9-inch wide wheels, right?

Damn 265/40/18s are going to be stretched on 10's. I'll have to put together a winter project 08-09 thread and post pics of what I've been up to.

Yeah 9's all around.

They will be stretched, honestly aside for a tiny bit of rub I'm LOVING this combo right now. It is so nice to have traction. It really only spins 1st a bit then the rest is all hook and go. Granted I'm only at 12ish PSI. But I cant imagine how much you will be spinning with the 18's.

Yeah get a thread up, its nice to see what some of the old time members are up to lol.

[Darius]

I'm busy as F#$@ thru Thursday of this week and I need Friday to catch up on other work stuff too. This weekend I might be able to work on the car, snap some more pics, and start a thread.

I'm not familiar with how the tires will seat on the new wheels but I'm guessing they won't be nearly as wide as the 10" stang wheels. I swear those wheels at the lips are like 12" wide. If the 265s don't fit or I can't get enough traction, I'll just jump up to the 295s BTW the new wheels arrive Thursday!!

[gawdzilla]

nice wheels. This happened to mine on Sunday

[Shocker]

nice wheels. This happened to mine on Sunday

Oh no! That sucks man. You seeing if the 240 could fly and came down to hard?

That is not good at all. For OEM wheels they are pretty expensive used.

Matt what kinda of thread wear are the tires?

[l0nestar]

nice wheels. This happened to mine on Sunday

AutoX / HPDE damage?

[Darius]

Cmon live dangerously! There are 2 perfectly good spokes left on that wheel hahaha

I bought brand new 265 MT DRs and haven't even installed them yet. 100% tread.

[Shocker]

Cmon live dangerously! There are 2 perfectly good spokes left on that wheel hahaha

I bought brand new 265 MT DRs and haven't even installed them yet. 100% tread.

Oh good, you should be alright with those! You will love the softness for traction.

Got my car aligned today she is driving very nice and straight as an arrow.

I'm really worried about my spec stg 3 clutch. On my 2nd to 3rd shift, when I pound it hard with a passenger (shifting at 7200). It doesn't instantly grab, it has a very slight delay occasionally... However when the weight is removed and its just me in the car it doesn't do this.

The clutch is rated to 515 ftlbs. I'm definitively not at that... I already adjusted my clutch pedal down in engagement hoping that would help. Clutch has around 12k miles on it but a TON of 1/4 mile passes(50+) in BPU form. I'm going to contact spec tomorrow and see if they recommend just a new disk, or an entire package. Bc I know at 20 psi this thing might be giving me issues...

I got laid off 2 weeks ago so money is also gotten tighter... ohhh yeah.

[Shocker]

Well was on the rollers yesterday (mustang dyno), was doing some decent things early at low boost. Car made some decent power (380@6500 on 13 psi), then we began to run into a headgasket issue, which it ended up popping by the end. Engine was blowing compression into the coolant passages under boost, which started as just a little bit of overflow, and progressively raised coolant temps while boosting, as well as dragging the power down with it. I'll upload the video of the runs once I receive them from my buddy Andrew.

Headgasket issue is most likely something to do with the surface finish on the head/block. Its a 5 layer Cosworth Gasket held down by ARP headstuds. The headstuds had been re torqued two days before this happened per ARP specs. Motor had about 450-500 miles on it.

Plans are to remove the head/inspect, hopefully all is alright. I'll check the head for straightness, and she then will hopefully be getting a stock organic gasket with fresh ARP studs. I'll know more once I take a good peak inside, the plugs all looked pretty good, not really any signs of pre-det. A/F's were 11.2's-11.4's.

Compression will rise to 9.3 doing this however..

I'll see, depressing times for sure. This car has fought me every step of the way after going to an APU setup. I'm trying hard not to just give up.

[mott6904]

Damn man i feel for you. It is always something break on that thing. good luck

[Darius]

Jeez this sucks!

[gawdzilla]

wow, that's horrible. hopefully the fix wont be too bad

[Shocker]

Definitely a major bummer for sure. I'll be getting my car towed home tomorrow morning and wednesday I plan to pull her back apart. I'll update with some pics of what it looks like. I have plenty of free time now so I suppose this gives me something constructive to do...

[l0nestar]

Oh Geeze. You have wonderful luck! Where _did_ you work previously? What was your CR with the 5-layer gasket?

[mott6904]

was this installation error? did you not have the block and head check for straightness when it was being built by the machine shop the first time?

[Shocker]

Oh Geeze. You have wonderful luck! Where _did_ you work previously? What was your CR with the 5-layer gasket?

I know I do it follows me everywhere.

I worked for Kasgro Rail Corp as an engineer my plant closed and the company is about to go under water...

CR was 9.0:1 with the 1.5 mm HG

The head and block were assembled by the machine shop, both were supposidly straight, and had the proper roughness for a MHG.

A local high HP DSM buddy of mine suggested more torque than what ARP recommends. Which was 80 ftlbs over the phone according to an ARP tech for the rb25 with the moly lube, and 85 with 10w30 oil. I did retorque these studs per their specs friday before tuning.

My buddy said he needed 105 ftlbs on his 12mm ARP's for his 4g63 to prevent sealing issues... I do not think our 11mm rb25 studs can take 105 ftlbs. I can ask ARP and do some of my own calcs to compare to their materials yeild to verify. I will also be measuring my studs length in comparrison to the new ones to see if they streched.

[mott6904]

man that sucks. Did you by chance spray any copper sealant spray on the gasket before install. It is a good idea to use this stuff on metal head gaskets

[Carryl]

Not sure what its worth but, i run FET sports 6 layer gasket on m 20.. with factory headbolts.. torqued to 100ft.lbs

[Shocker]

Heres a vid of one of the pulls to 6500, if you check out my account there is also the whole video of this with a bunch of f***ing around before hand.

http://s27.photobucket.com/alb...7.pbr

thanks for some of the suggestions guys. My builder doesn't like copper spray and it was not used.

I got the car home this morning, plans to tear into her tomorrow.

I'll keep this updated as I do.

[USMCgetsome]

nice 240sx tramp stamp shocker!!!! lol!

[l0nestar]

nice 240sx tramp stamp shocker!!!! lol!

I saw that and sincerely hoped it wasn't real, or on you...

[GTRs13]

I do not think our 11mm rb25 studs can take 105ftlbs

Of course they can!

Later 7-bolt 4g63's have a smaller head bolt then the 6-bolt 4g63's.

12mm on the 89-92' 6-bolt, and 11-mm on the Late 92-99' 7bolt.

I have built (Headgasket, Balance shaft removal, if you call that "building") 7-bolt's that go high 11's in the 1/4 mile on ARP 11mm studs, so this should not be your issue.

Like the RB, stock 4g63 torque is only 85, but I usually torque to 95-100, but they can definately do 105ftlbs easily.

And as far as "Roughness" of your deck surfaces, MHG's require a Mirror-like finish on both sides.

I am just referencing this, as you mentioned the surfaces had the right "Roughness" for the MHG. Just trying to clear that up as well.

I missed the total timing used on your 11.2 AFR run as well, what was it again?

[Shocker]

I saw that and sincerely hoped it wasn't real, or on you...

Photoshopped, we have a few local ***s with giant Firebird tats on their bodies. I figured I'd share in their gheyness.

Timing was 16 or 17 degrees on 13 psi 11.2's-11.4's a/fs. I'd have to go back and look at the ECU map.

[Shocker]

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.

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

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

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 psipump gas 93 octanetiming 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.

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.

[RustspecS13]

Wow that really sucks.

Possible ideas. Are you running the same injectors as before?

It kinda looks like hot spots. IE the injector shoots down the intake valves and misses the two hot spots you see now.

I got the idea from diesels, as a guy at work has one and we've been talking high performance stuff for the last couple weeks, and they have weird piston designs made to cope with 1000FT-LBs+ and high EGTs.

Im not saying your using the wrong pistons, but maybe something in your setup is causing the fuel/air mix not to fill the chamber properly causing hot spots

Second maybe it is too lean. My buddy has a stock VG30E in his maxima running 400whp on all stock internals. He used to run ~11:1 afr and kinda conservative timing. Now he runs ~10:1 afr and much more timing making more WHP per PSI then before, hes just using more injector to do it.

Since you are running a microtech maybe you have the injection timing set wrong. Thats a big thing with diesels is getting that right to make the most power and not REALLY destroy the engine.

IIRC injection event timing (or w/e they call it) is adjustable on the microtech, so when your running a small engine on meduim boost it stands to reason the fuel timing needs to be right. Maybe yours is different for what ever reason, maybe you need to check that.

Now these are just ideas, kinda different applications that might apply to you but Im not really sure.

~Alex

[Carl H]

is the micro tech possibly effin up and causing distortion in the cas signal?the stock ecu has 2 processors dedicated to decoding the cas signal as well as queuing it for processing.that damage looks alot like damage similar to when my engine went...afrs were fine and timing wasnt TOO insane but i suspect it had high egts.

also rustspec might be on to something...bad lag time values can definately cause distruction due to the injectors not pulsing correctly.

[l0nestar]

Holy crap! Is that (the remains??) of your quench-pad?

[GTRs13]

It looks like you are rich on spool-up and at your torque peak.

When you said 11.1 AFR from 0psi to 16, was that to keep everything cool?

Or to make an impressive curve?

It seems to me that your timing is wild as well.

Since it ramps up to 21 degrees around your torque peak, with the Rich AFR you may be creating extremely high cylinder pressures before spooling.

Then it spools and continues the Spike in cylinder pressure.

I'm sure you've heard richness kills rings. Its not that rich, pretty safe IMO.

However, its your timing that is erratic, and spiking the cylinder pressure around torque peak, a very vulnerable time in an engines power curve.

Do you have any knock going on? Or can you not tell?

[Darius]

Injector lag was a question I was going to ask too. My car idled fine, but not good until I adjusted the lag settings per Deatchwerks specs and now the engine idles great and runs fine with EGTs in the 1400s at max.

How are you running the fuel pumps? In series or parallel? It sounds like you're running them in parallel which might cause issue especially necking down into a -6AN line. I'm going to do some pump research here and look into that some more. I'm wondering if that walbro is even doing anything with the 044 pushing against it.