Engine builders take a look

[whitehot84]

I have dual 340's.
Nick, I think you may have hit on something. I usually use high octane Renegade fuel but have had to put pump gas in it a couple of times when I was out on the road. I turn the boost down but pre-ignition could be the culprit.

 

[whitehot84]

what up with the 2 circles in the middle of the piston?looks like # 3 doesnt have them.Also the piston looks really clean,carbon build up differs from the others,coolant leak?

That is just the machining marks. The rest have carbon deposits so they don't show. No leaks. Used copper gaskets with o-rings.

 

[jasjamz]

When using copper gaskets and o-rings you really "make" the pistons and bearings the weak link.

 

[bison]

That would be the first piston to lean out. It's the last injector in the rail to get fuel.

Have to disagree with this logic. The fuel rail is pressurized with the same pressure from #2 to #1. The pressure is controlled by the reg. which is after #1. The fuel rail will have 40-50-60 or whatever psi @ all injectors @ all times. I've seen the same argument with air flow being more to the 2 back cyl.--have yet to agree with that one also.

The only way you would know this for sure is if you logged the pressure on both sides. when the injectors are large and the dc is high I really doubt the pressure is equal. I've hurt #1 at least 3 times in since I've owned these cars. It wasn't ever a problem till over 700hp especially when trying to wet flow the stock intake with alky. Over 700hp the statistics show #1 gets too hot more than any other hole. If the pressure at the rail inlet is 80 psi and it's 70psi at the regulator you are going to be in trouble.

+1, thats where all the cool kids hang out and smoke cigarettes



On the nissan site I go on, I always get a good laugh about everyones "build" threads , yeah a beat-up 240 with flat black paint and a dildo shift knob is a "build" thread. Whats even worse is some people tell them how cool it is

re of ex gas and correcting based on it. One side of the engine at 10.5:1 and the other at 11.5:1. Ouch. I figured out the solution.

 

[bison]

Looks like posting from my phone works like a bag of chit. Not even the person I was trying to quote and part of my post missing. Oh well

 

[GARY HARVEY]

Call Diamond

Get RA and let them determine what caused your situation.

I've been running a set of those with no issue..

It will be interesting to hear their results.

 

[tcgn]

repuatable engine rebuilder needed in or near San Francisco

Can anyone recommend a good and reputable engine rebuilder for these motors in or near San Francisco? I' m buying another block so I will need a rebuilder that I hope to trust.

 

[DCVING 6]

Can anyone recommend a good and reputable engine rebuilder for these motors in or near San Francisco? I' m buying another block so I will need a rebuilder that I hope to trust.

message John Wilde and see who he says... think he's in your area.

 

[quickt]

Had the engine out to do some detailing and decided to pull the heads and have them messaged a little more. What to my dismay do I find in number 1 hole . . . . . . . . . . . .



These are diamond pistons. My engine builder says no sense in replacing one piston. It will more than likely do it again. The top ring groove is cut to close to the top. There is only about 1/16th inch of material between the ring groove and the cup.
What do you guys think about this???
He also says this cylinder was running lean. Why only one cylinder???

Those pistons are quite simply junk. The other thread explains it all. Buy another set (not diamonds) and get back to racing.

 

[Chuck Leeper]

X2!

Wrong design for these engines. This is not the fist time weve seen this

looks to me as tho it's one of the we have all of our "popular designs" on the shelf.. Then, they made a turbo piston out of a shelf item.

 

[Chuck Leeper]

Was looking for a stock rail, fpr, and a set of injs, to set up on the bench, to see if #1 is really the problem position. The parts never showed up.....

 

[pacecarta]

bad design , once theres a fueling issue on #1 , much easier to do with 93 and alky that cant keep up either to leaks or simply volume setting or lonnies gravity theory , once its lit it sets of a chain reaction that will take out the piston and the gasket and if your lucky and on iron heads thats where it will stop , but with alum heads then the head starts to burn through and takes the head and the block with it

stock dish design like the oe is what i perfer , jE for me

heres a recent pic , not mine and i had no part of it till the damge was done.
big surprise... its #1 , wrinkled up and damaged the cometic on that cylinder as well which led to coolant push and overheat

and yeah some will say detonation caused it , yeah i agree but have to wonder if the piston design was the cause of the preignition that led to the detonation in a situtuation that with a dish design piston would have been able to see in the tune correct and move on rather than tear it down for damage like this

 

[turbofabricator]

Bison I'm posting from my phone too so bear with me. I think you figured out the #1 piston problem with out even knowing it. It is NOT the fuel rail being an issue but rather the wet flow alky being the problem now. Alcohol has mass and will follow the path of least resistance and will fill the back of the manifold with alcohol but miss the front with all but completely atomized alcohol. We use to blow the rear head gaskets but after experimenting with alcohol 15 yrs ago we started popping the front gaskets. We use a power plate and stock fuel rail and run 10.12@136 with no problems. Walbro 340 and dual nozzle Razor system. Now we just stepped up to a Stage II block and champion intake and rails. Well see how long it takes to sort out the issues with this combo.!

 

[Pronto]

Just thinking out the top of my head, would a different intake arrangment help that issue of alky distribution? Spraying after the throttle blade? Direct to the individual runners kind of like an NOS system?

 

[gntyDenver]

Thought it was just me...My last motor did that with the same piston THEN i CHECKED THE PART # AND THEY CAME BACK AS 3.8 NON TURBO PISTON BUT THEY WERE DISHED SAME AS YOURS....CHECK THE PART NUMBERS U MIGHT HAVE ALL THE WRONG PISTONS.

 

[whitehot84]

Thought it was just me...My last motor did that with the same piston THEN i CHECKED THE PART # AND THEY CAME BACK AS 3.8 NON TURBO PISTON BUT THEY WERE DISHED SAME AS YOURS....CHECK THE PART NUMBERS U MIGHT HAVE ALL THE WRONG PISTONS.

I'm thinking they took an NA piston and machined it to drop the compression. They just didn't realize how close they got to the ring land. It is just too thin and caused a hot spot.

 

[Mike Licht]

the reason that the dish is shaped the way it is, is because Diamond will map the chamber in the head to design the dish. Call Mike Pinella at Diamond 877-552-2112