M20b27 fuelling

[964russ]

Hi, trying to finish my e30 build.
But have hit a problem.

I think its overfuelling, its pinking at about 3k.

I'm on my 2nd chip now, neither has sorted it.

Before I pay £500 to wayne for rolling rd, any ideas?

M20b25 with ETA crank, 1.7mm decked from block. Schrick 288 cam.
M50 injectors, bbtb, 6 branch.

[964russ]

Think its piston slap!!!

Anyone ever had any experience?

[boiliebasher]

I'm genuinely intrigued by this question. I've not personally built a stroker engine, but it was definitely on the to do list in the future!

I have read somewhere that this supposed "piston slap" phenomenon was a known issue, in part due to the use of 130mm rods.

Your build specs seem like a winning combination imho, and I'd like to have a similar setup one day so I'd be interested to see if you get a definite answer to the problem you are experiencing at 3k

Good luck and all the best fella and please keep us posted with any updates!

[964russ]

Dont think its piston slap now.

Think it's over fuelling.
Had a read and apparently this cam needs better engine management, standalone to get the best from it.

Time for a standalone ecu.

[steve_k]

Dont think its piston slap now.

Think it's over fuelling.
Had a read and apparently this cam needs better engine management, standalone to get the best from it.

Time for a standalone ecu.

the last time i heard of piston slap was after using forged pistons in a 2.1 pinto, it has been known to happen in m20's if using forged piston's, normally when the engine is stone cold.

over fuelling? best get it on a rolling road & get it checked out & mapped, & fingers crossed the issue is then sorted.

[steve_k]

justa thought, you could always go with the DET3 piggyback ecu as its a fair bit cheaper.

[flybynite]

Personally I don't think it is piston slap. Depending on the cause you would mostly hear it at idle when cold not 3000rpm. Pinking is generally caused by running lean not over-fuelling

My thought is piston/valve contact

A 2.7 done with 130mm rods and head skim needs properly dialling in with a vernier as the head skim throws the cam timing out.

That is without putting a 288 in it.

What pistons did you use? Were piston/valve clearances checked when building it?

You will likely need a piggyback or standalone but best check the basics first

[964russ]

Yea it's on 130mm rods, 2.5 pistons, all lightened and balanced.
Theres no contact, checked during the build, and removed the head again to fit a better head gasket.
It's on a katcam verbier, and we have adjusted it for hours. It now starts first turn, ticks over (lumpy due to cam). Flys when revved, sounds like a super bike!
You can smell fuel, we adjusted the afm, got it better.
Swoped the chip again, and the rattle noise is definitely less.
Making me think its 100% fueling issue.
And a standalone is looking like the best way to get it right, can remove the dizzy then as well.

Only had the car 5 year! Need to get it finished.

[964russ]

Det3 very interesting.

I'll have a read up on that, cheers

[964russ]

Another thing, its miss firing from tickover.

Fine when revved up.

Plugs are fine, new everything

Possibly due to fueling issue?

[964russ]

Ordered standalone

[steve_k]

Ordered standalone

let us know how you get on with it.

[964russ]

Update.

Had the standalone fitted, they spent 4 hours getting it right.
Got the fuelling spot on.
But wont go any further with a map, due to the rattle.

The engine rattle is still there!

The tuner reckons piston slap, said change the pistons.
He allso noticed sum very fine metal in the oil, like glitter.
Suggests sumthink goin wrong inside.

[964russ]

Looks like something went wrong with the build.

Wont know till it's back out!

Heard about the possible 130mm rod problems, so think I'll fit the original 135mm rods with custom pistons.

Allso been offered a m54b30 crank, rods & pistons, dunno anything about that setup.
Will it fit in m20b25 block?

Allso does anyone know wot crank the sctnizer 2.7 used?

[reggid]

metal in the oil filter/oil is not piston slap, something else is fubar unless you figure out what the same mistake may be made on the next.

m54b30 crank custom pistons and 135mm rods will with a couple of mods for clearance/interface
the m54b30 rods/pistons/crank wont directly as the stack height is too high for the m20 block without some mods.

most of the name brand 2.7 e.g. Alpina would have got special Mahle/KS slugs made with the 135 rods

[steve_k]

I dont know about the ACS 2.7 but my hartge 2.7 has the TD (forged) crank, 135mm rods & custom pistons,

Some say alpina/hartge/ACS used the ETA crank in some of their strokers & the TD crank in others,

Doesn't seem to be any rhyme or reason as to why they used either.

[flybynite]

Some say alpina/hartge/ACS used the ETA crank in some of their strokers & the TD crank in others,

I think there is a bit of confusion because there are two different M21 cranks, one lighter than the other, The lighter one was generally used for OEM Alpina strokers

The problem is it has a similar weight to the cast eta crank and because the weight circulating on the net people think it is an eta crank not knowing what they were looking at.

[steve_k]

Some say alpina/hartge/ACS used the ETA crank in some of their strokers & the TD crank in others,

I think there is a bit of confusion because there are two different M21 cranks, one lighter than the other, The lighter one was generally used for OEM Alpina strokers

The problem is it has a similar weight to the cast eta crank and because the weight circulating on the net people think it is an eta crank not knowing what they were looking at.

I'll hold my hands up & admit I didn't know there were two versions of the m21 crank.

I couldnt tell younwhich mine was as it has had extensive work done too it before i rebuilt the engine.

Learn something new everyday