ncmudbug

Back at you, Cobra! I hope everybody here has a Merry Christmas and a hugely happy New Year!

splinter

It’s probably reasonable in this instance to set aside conversion errors owing to language differences. I’d wager a round at the local watering hole that your standalone ECU shouldn’t be commanding “13 af, 40 deg total timing at 6000 rpm.” Running ‘em too lean with too much spark advance is a quick way to destroy an otherwise sound engine.

Don’t follow Canadian touring car racing, although I certainly admire your willingness to get after it in a M271-equipped coupé. Not going to disagree with your forensic metallurgist's findings. Note MBUSA’s policy is that the head never be surfaced in the event of measurable warping or other deck irregularities. Its casting is already woefully thin as delivered. Tossing it into the nearest recycling bin is warranted should it prove defective; it’s merely another consumable.


Nonsense. Know you mean well in spite of your hellacious advice. You’re aware that the 1.8-liter M271 has a nominal compression ratio of 8.7:1, yes?

Several here have successfully utilized artificial aspiration of 17+ psi with their OE pistons and long-block fully intact. Barring manufacturing and operational defects, judicious tuning is imperative to help ensure reasonable service life. Machining a cast piston’s crown -save for minimal relieving to accommodate higher lift and/or longer duration camshaft timing events- is an invitation to disaster. Did you notice 427cobra’s pistons have already proven to be too weak for his circumstance? Additional peripheral deck height clearance often counterintuitively increases detonation by reducing swirl-induced quench properties.
Trust you’ll someday share the nuances behind your “10-second” E55 transplant. :y

C230 Sport Coup

Well, just catching up on this thread.
Had to laugh, so many haters.
Reminded me of a guy who posted he'd made his own crank pulley,
removed the SC muffler, posted a nice vid of his red 02 C230 coupe,
and before we could find out how to remove the
SC muffler or what it was, he was banned for merely suggesting that
he might make more pullies and maybe he might sell them.
He never did.
That pulley eventually turned up for sale, I think here maybe.
Oh the irony.

There are some vids out there of a C230 sedan race car.
I've only seen other C230 coupe racecar, and that was the Autohauz guys car,
w/ the 2.3L. Much more robust engine.
BTW. they were selling some carbon fiber bits they had custom mfg'd and
a special racing diff and tranny, not to mention the whole car.

Nice to see someone campaigning an Orion Blue coupe!

edgarinho10

Amazing piece of machine.

edgarinho10

I thought the title was just a figure of speech.

W203E35

I want my car to be that fast (I'm sure the tranny won't be up for the challenge). The supra is 800rwhp

edgarinho10

Off Topic:

What's better a Supra Or Skyline?

Ausmbtech

What is the top piston ring gap?
Are there any score marks in the cylinder bore?
Can you post a top and side picture of one of the other pistons.
What spark plugs (temperature) are you using? they would need to be 1 to 2 ranges colder than standard.
Which side did the piston break? intake or exhaust side?


Have a look at this link http://www.kolbenschmidt.com.tr/pdf/...-02_en_web.pdf

yvanlavoie20

http://www.kolbenschmidt.com.tr/pdf/...-02_en_web.pdf

WOW

good info here


thanks

yvan

fookoo303

That's very relative. Both are good but depends on what your trying to do. Supra is RWD and Skyline is AWD.

They both have potential to produce 4-digit horsepower and torque.

427cobra

Thanks for the advice, after the engine is back together I plan on doing more dyno work and start with something like 11 af and 25 deg timing and go from there

427cobra

What is the top piston ring gap?
12 thou

Are there any score marks in the cylinder bore?
No score marks

Can you post a top and side picture of one of the other pistons.
Tomorrow I’ll have some picks for you
\
What spark plugs (temperature) are you using? they would need to be 1 to 2 ranges colder than standard.
I’ll check that to night.
Which side did the piston break? intake or exhaust side?
Peace missing on intake side, some melting on exhaust side

edgarinho10

For some reason I want to get an R34. Just wondering if it would be something worth investing in.....

Considering we do live in the states.

yvanlavoie20

12.5 af is perfect for power, anything richer is bad for power.
if it was my engine, i will try around 20-25 deg... checking egt...not enough timing = egt high, too much timing = egt high, you will see a sweet spot between too high and too low, thats the best point for reliability.

wich fuel you run un your engine ?

yvan

Ausmbtech

Based on that info I would open the top ring gap slightly to 15thou, this will reduce the chance of the piston rings binding and adding pressure the the piston ring lands. I would also fit colder spark plugs (start 2 ranges colder than standard, if they foul then move to 1 range colder. std plugs are too hot for you application and will cause detonation.

Have you considered getting the tops of the pistons coated with a ceramic coating. I don't think you have a tuning problem because the center of the piston has no damage. I think it's just a heat problem.

Glyn M Ruck

+1

427cobra

Ausmbtech; here are the picture,
Pics 1 to 3, piston # 1
4 to 6, # 2
7 to 9, #3
10 to 12 # 4

sparh plugs: Bosch, #F6mpp332

427cobra

The other 6 pictures.

427cobra

93-octane pump gas.

427cobra

Have you considered getting the tops of the pistons coated with a ceramic coating. I don't think you have a tuning problem because the center of the piston has no damage. I think it's just a heat problem.[/quote]

Yes I have and I more then likely will, I’m going to put all the + on mi side.

yvanlavoie20

can you use some racing fuel ?
If yes , buy some high octane fuel
if not, add 15% of toluene, it is a component of the fuel

search for rocket fuel in google...lol

in my opinion your pistons are burned from too much heat... timing too high and-or too lean.

i ran my engine with this and have GREAT result.like :

9.2 cr 21 psi of boost and too many parts of transmission broken...too much wheel spin...lost traction ... broke a rod but piston are ok

but anyway you need octane to prevent preignition and piston melting.

Hypereutectic pistons are very sensitive to preignition.

Yvan

427cobra

I tried alcohol but I get those terrible headache lol.

The rules say (commercially available pump fuel) what ever that means.

yvanlavoie20

http://www.2phast.com/500e/techdocs/toluene.htm

LOL this is an ingredient of normal fuel !!!

premium fuel contain 10 to 30% of this

Yvan

PS : this is THE solution hihihi

Ausmbtech

After looking at the photos it's definately a heat problem and not detonation. If you look at the first photo of the undamaged piston, the RHS is clean of carbon whilst the LHS has cabon on it. The RHS of the piston is running MUCH hotter and burning the carbon away. The spark plug is located in the center of the chamber so it's a fairly even distributuion of heat in the chamber with the usual addtional heat on the exhaust side.
I would beconsidering custom forged pistons if the rules/budget allows, otherwise definately get the piston crowns coating with a heat reflective coating.

Ths std pistons can take heat, but the extra heat you're geneating and for the long periods of time they just can't take it.

Glyn M Ruck

Do not add toluene ***** nilly to pump gas. It is a very poor octane booster & slows down flame front propogation. Try & get some AVGAS. The fuel must have a balanced distillation curve. Extra anti knock resistance is only of any benefit if you run more advanced timing. You need to run the most dense fuel the engine can fully combust. Higher density = greater energy. Remember AVGAS is still leaded so it will destroy your Cat but I don't know your rules. You probably don't give a damn about the Cat - can you remove it?

You are not suffering detonation so octane is not your problem (although the timing might be retarding itself at the onset of knock.) so you might not be running as advanced as you wish if you still have the knock sensor in circuit.

BTW - Are you running a decent oil cooler? The oil can only cool the underside of piston crowns if it, itself is being adequately cooled. Watch bulk oil temperature & fit an oil temp gauge.