2.0 head on the early eta block? (cr too high!)

[liam012]

Has anyone else done the 2.7 conversion using eta block crank rods and pistons and just a 2.0 head? (2.5 intake and fuel delivery).

Therre must be a few of you?

What issues if any did you have with timing/fueling/pinking

or was it plug and play?

The reason is i suffer from what i dont know is Pinking/pre igntion or detonation - tbh i havent a clue all i know that it makes a (bean can with two or three dried peas rattling" sort of sound under medium to full throttle under load especially up hills . i have got a vernier to install to try and help with it but my problem is that i dont know what the general rule of thumb is - i thought in my case retarding the timing would be the way forward? what have you guys done?

Thanks

[chu346]

My car runs fine, no issues whatsoever.

Have you got a chip from ant? that's what i'm running.

Have you tried using superunleaded?

[chu346]

Also what cam do you have and what do you think the c/r is?

[liam012]

268/268 cam
i have no idea exactly what the comp is but others have estimated it to be 11.0 : 1

[liam012]

chu did you use the 2.0 head?

[Ant]

11:1 is very high Liam

O/T Ms arrived today dude

[jaistanley]

11/1 isn't that high for a head that produces so much swirl and (I assume) has a large area of squish surely? Also, the higher duration should reduce the dynamic compression ratio at lower rpm too? I'm no m20 expert by any means though!!

Perhaps its time to upgrade to MS?

Jai

[liam012]

oh its definately time for that - but now curiosity has me as no one else seems to have had problems with their 2.7 conversions and i can find a million threads where people say "oh yeah slap the 2.0 head on the e block" but i cant seem to find people who have actually done it-
i know andymagicdid it ages ago but he's of the forum now and sold up i beleive, i remember him having pinking over 5000 but he nver mentioned the under load problems i am having. and in fact the higher i rev the more my problem goes away.

[jaistanley]

Sounds like a squiffy advance curve then? Or perhaps under-fuelling.

Megasquirt it beeeatch.

Jai

[Ant]

The chip is sound Jai , 2.7 specific advance curve and fuelling

Liam has an LM-1 WB meter, and the fuelling was reported to be spot on in a previous post.

[jaistanley]

Not slating the chpi dude... You guys know more about the details of this stuff than I ever will! Is the chip 2.7 eta/2.0 head specific BTW?

Just trying to work out what the pinking is about.. I've thought about this engine due to the high comp ratio

[chu346]

chu did you use the 2.0 head?

yes for about 8000miles now and my c/r is more like 10.2:1 the later block.

No problem at 5000rpms only when I get to 7000rpms, darn limiter

What about using a thicker oem headgasket to drop the c/r slightly?

Have you tried superunleaded.

[liam012]

YEEEEEEHAAAAAAAA!!!!!!!!!!!!!!!
i tried a different brand of octane booster on the way home - as i had exhausted all avenues od testing known to me, and you would not beleive it - it actually bloody worked!!!! no more horrible sound - i added enough to raise the octane rating 4 points and that all but cleared it in any gear - unless i am really cruel up a hill in 5th i can barely make out a whisp of it.
THIS IS EXCELLENT NEWS FOR ME!!!!!!
I have been troubleshooting this for so long was begining to give up and it ended up being the fiorst thing i tried just that the silkolene pro boost was crap compared to the clp i got.
SO what does this mean about my engine if i need to add octane booster to avoid that horrible sound?

[chu346]

c/r is too high, you need to lower the c/r with either a thicker head gasket or decomplate

maybe tescos 99octane would do as a temporary fix.

[hairydave]

As above, also keep using the octane booster until you find a more permanent fix.

[Templ8e30]

I've built my 2.7 with a 2 litre head, skimmed to raise the CR to 10.5:1.

I'd never had trouble with it pinking until the Mrs put a full tank of ASDA unleaded in it at the weekend, pinks like a mutha now and drives like a 320i. It missfires at idle too. Fecking cheap shit petrol

Cheers,

Iain T

[daimlerman]

I try to always use superunleaded or BP ultimate,I have had no pinking issues at all.Has your head been skimmed to the point of no return?

[liam012]

i think the problem may be the early e block gives a comp ratio of 11.0:1
still researching that

[Ant]

11:1 with the 731 head should still gaive a static CR of 11:1

the cam will reduce that a little when running, but shes still too high IMHO Liam.

see what MS can do to reduce it, but I can feel a fatter H/G on the cards.

[liam012]

fit this engine in my new shell after resting it up for a year!
4.1 diff as i retired the 3.46 and the 3.64 is being rebuilt.

would you beleive, no octane booster , no vernier , and even so no pinking!!

this means quite simply the 3.46 was the cause of the pinking - or more accuarately; longer duration and more load in a given gear than what it was meant/mapped for.

the car is a real mover with this diff,

ironicly i started the day by doing a compression test (which was 230.225.225.225.225.230)
and on a down side finished the day with a blown headgasket i think.

bit of a kick in the guts but getting to know this engine well again, it's a real bugger!