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Rb25/26 Serious Issues - Help/opinions

Shockster0429
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femno Grand Master

femno

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Posted

Why do you keep comparing your setup to other setups?

With such a high CR how can you? It is directly related to knocking issues, saying this car runs X amount timing up top and yours is less is no comparison.

And no knock detection? Standing by the car doesnt cut it! With exhaust noise, gate noise, spool noise, how would you hear anything at all?

Why would you run 2 different pumps and Y-Piece them together?!

I had my first engine built but a guy who did mostly V8's. It lasted 8,000kms.

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Guilt-Toy Grand Master

Guilt-Toy

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Posted

give the guy a break.

The guy is running very low timing in the ecu, its weird how these microtechs work, i will explain.

The timing map you see with the timing sitting on 21deg is the rpm timing, then when it hits boost the ecu retards the timing as the boost comes on.

at 16psi the guy has 9deg of timing being removed from the base timing, so its really running about 12deg. thats pretty retarded, so for a high compression engine it should be ok.

I do think there is a inconsistency with the ECU and that the engine is not actually seeing 12deg, it might be seeing 24 for all we know or it could be bouncing up and down like a yo-yo.

upgrade the ecu and try again. long live the third engine! ohhhh also please get rid of those injectors. that is a must too.

Shockster0429 Enthusiast

Shockster0429

Posted
  • Author
Posted
give the guy a break.

The guy is running very low timing in the ecu, its weird how these microtechs work, i will explain.

The timing map you see with the timing sitting on 21deg is the rpm timing, then when it hits boost the ecu retards the timing as the boost comes on.

at 16psi the guy has 9deg of timing being removed from the base timing, so its really running about 12deg. thats pretty retarded, so for a high compression engine it should be ok.

I do think there is a inconsistency with the ECU and that the engine is not actually seeing 12deg, it might be seeing 24 for all we know or it could be bouncing up and down like a yo-yo.

upgrade the ecu and try again. long live the third engine! ohhhh also please get rid of those injectors. that is a must too.

Thanks for looking it over Guilt-Toy whats exactly how both my tuner and myself felt about the tune.

It sucks however having conflicting reasons for this. Where as I'm on the side that this is microtech/cas related issue. Where on the microtech forum they are disagreeing, posting an rb26/30 vid reving to 9500 with a big single with no issues running a Nissan CAS.

The guy blamed my wiring, I posted up how I wired it, then he says its correct, and if it wasn't the engine wouldn't have ran at all... contradiction much? Then he goes back to blaming the tune.

I wish I could back track two weeks here, and physically free rev the engine through the entire band with a timing light on the balancer and compare physically timing at the crank to what the microtech is actually reading. That is no longer possible however...

If I do redo this for the 3rd time I will look into another standalone. The vipec system is something new to me I'll have to read more about it. I'd like to stay on a standalone side for sure since my factory harness is gone. Any more suggestions of what works with NO issues?

As for the injectors if I do what I want to do, they will be gone, and precision top feeds will be in place, along with a dual feed rail to get rid of the dreaded "Y"....

James_03 Mentor

James_03

Posted
Posted (edited)

Looks to me like a killer combo of:

1. Shit fuel (This is a contributor but I don't think would have been the overall cause)

2. Raised compression due to running the same cylinder head from before

3. A fuel setup that sounds questionable (What lift pump is it using as you mention both the walbro and 044 using a Y very close to the rail, so what's back in the tank?). Either way you can illiminate the walbro alltogether I think as it's just not a requirement, 044 intank should see you get there easy.

4. Listening for knock? I don't think so. Proper mircophones on the engine is what is usually required

I doubt the microtech has anything much to do with this at all. I ran the shittiest mt8 with wasted spark on an rb25/30 combo and it ran fine with a nissan CAS. Injectors are also questionable, drop them and go for some nismo's or SARDS etc.

I was running hi flowed JECS rb25 injectors for a bit, very nasty. Spray pattern ends up like a garden hose basically. (Yes I read the part where you got them flow tested, drop them anyway but)

Hope you get it sorted but.

Edited by James_03
Shockster0429 Enthusiast

Shockster0429

Posted
  • Author
Posted
Looks to me like a killer combo of:

1. Shit fuel (This is a contributor but I don't think would have been the overall cause)

2. Raised compression due to running the same cylinder head from before

3. A fuel setup that sounds questionable (What lift pump is it using as you mention both the walbro and 044 using a Y very close to the rail, so what's back in the tank?). Either way you can illiminate the walbro alltogether I think as it's just not a requirement, 044 intank should see you get there easy.

4. Listening for knock? I don't think so. Proper mircophones on the engine is what is usually required

I doubt the microtech has anything much to do with this at all. I ran the shittiest mt8 with wasted spark on an rb25/30 combo and it ran fine with a nissan CAS. Injectors are also questionable, drop them and go for some nismo's or SARDS etc.

I was running hi flowed JECS rb25 injectors for a bit, very nasty. Spray pattern ends up like a garden hose basically. (Yes I read the part where you got them flow tested, drop them anyway but)

Hope you get it sorted but.

1. Idea I've considered it, however its the same exact gas station I run in my WRX. Which is tuned for 93 octane (US) the WRX has no issues. Ideas on testing the octane level? I could siphon some out and give it a try I suppose. I just have no idea where to take it.

2. Raised compression? You mean 9:1 which is what a stock RB25 is anyway? That is not raised that is factory level. People have made high HP on pump gas with a factory bottom end with stock compression.

3. Fuel system: Look in the background of this picture.

IMG_0056.jpg

You see the blue 90 degree fitting? This is coming off an inline filter, below the filter is the Y for the dual pump setup. There is about 2 feet of fuel line before the rail where its just one line.

IMG_0239.jpg

Look at the top view and you can see the line running behind my coil packs. The end of the fuel rail has the stock line welded shut, and a -6 steel fitting welded to the end of the rail. This setup is less restrictive than factory. Its not the problem with my issues, period.

4. This is not looking like a knocking issue, this a looking like a pre-ignition issue. Lets take your example - Okay you use those det-cans. Whose to say there was enough time to even distinguish between regular engine noise and knock (if there was any) before destruction? This damaged happened over a matter of a few pulls.

Shockster0429 Enthusiast

Shockster0429

Posted
  • Author
Posted
Can you be sure?

You never can be sure no. However the power it made on the first pull was ballpark where it should have been based on others setups the motor pushed out a bit of coolant. Then the limiter was raised 500 rpms higher and every pull after that the power dropped off as the engine pissed more coolant. Until finally the HG let go. This is over I believe it was 4 total passes.

I guess a better way to state it is. "This damage was only evident over the course of a few pulls."

blind_elk Grand Master

blind_elk

Posted
Posted
This is not looking like a knocking issue, this a looking like a pre-ignition issue.
They are variants of the same condition. And the condition is an uncontrolled burn of the fuel/air mixture.

And, if you can hear detonation, then it's already too late - the damage has been done.

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