E30 Zone

hi all, i have a 2.7 eta running with a 2.5 head. been great for a year but the head gasket has gone! ( now before ripping it apart, i have a 2.0 head kickin about. i have read the sticky but still like confomation. will my E30 have as much power as it did if i put the 2.0 head on??

From my limited knowledge there is very little in it power wise.
Daimlerman has a 2.7 with an eta bottom end and a 320i head and it makes about 175bhp? and 180+ftlb?
Cliffybabe is using a 325i head and his car puts out pretty much the same power.
The 325i head has larger ports and valves and I would assume a different cam whereas the 320i head has better matching combustion chambers to for the eta pistons.
I would imagine you'd get better low down torque with the 320i head and better midrange/topend power with the 325i head

I stand to be corrected though

oakey wrote:From my limited knowledge there is very little in it power wise.
Daimlerman has a 2.7 with an eta bottom end and a 320i head and it makes about 175bhp? and 180+ftlb?
Cliffybabe is using a 325i head and his car puts out pretty much the same power.
The 325i head has larger ports and valves and I would assume a different cam whereas the 320i head has better matching combustion chambers to for the eta pistons.
I would imagine you'd get better low down torque with the 320i head and better midrange/topend power with the 325i head

I stand to be corrected though

I'd say that answer is pretty much on the money.

Yes,the above is pretty much the correct thinking.The 320(731 casting) will match your pistons,the 325(885 casting) does not,but the larger valves compansate.As you have to pull the thing apart anyway,why not have the valve seats cut back and stick in the 325 valves? gives you the best of both worlds.Cam choice will dictate the power band and position,standard 325 cam will give exellent lowdown grunt,tailing off above 5000rpm,aftermarket cams will just destroy the low down power(below,say,2000rpm) but will give fantastic top end,still be going when the rev limiter cuts in.Best of the standard cams is the difficult to find 323i version.

323 cam is around 270/270? which is bang into the aftermarket cams

daimlerman wrote:Best of the standard cams is the difficult to find 323i version.

Simon13 wrote:323 cam is around 270/270

I see people keep banging on about the 323i cam being the best, but all the information I've ever seen says that all L-jet cams are 253/253 and Motronic ones (except the eta, of course) are 260/260.

spot on Oakey

I had a standard eta bottom end, a 320 head with 325i valves, a 272 cam and no other mods, I got 193bhp with an off the shelf chip.

chu346 wrote:I had a standard eta bottom end, a 320 head with 325i valves, a 272 cam and no other mods, I got 193bhp with an off the shelf chip.

That's about on the money,I have 178bhp with a stock 731 head with a 325 cam.How do you find drivability between idle and,say,3000rpm with the 272 cam,please?

Could be better between idle and 3000rpms but not bad though, it needed tuning, I could smell it overfueling sometimes at stand still, and the exhaust pipes were black. I say the most important thing when building an engine like is getting it tuned properly because very few 2.7 are the same spec and a generic chip won't do.

hi, thanks for all ur reply's, think ill throw the 2.0 head on with the 2.5 cam. and if im lucky gather the cash to get the valve seats ground bk to use the 2.5 valves. ive been dyin to turbo it, so ill probly pick ur brains soon

The 320 head will give a high c/r so it might be worth making it turbo spec now instead of throwing away money. So possibly 325 head to give slightly lower c/r or 320 head with decomplate or piston swap while the head is off, i think it can be done with the block in situe.

Holy shit! All these 2.7's and such small gains!

bss325i wrote:Holy shit! All these 2.7's and such small gains!

These are budget builds though! basicly built like a 325 engine with 0.2litre extra capacity. Yes I had a 272 cam but if i also had a 6 branch and a good remap I would have had some v.good figures.

bss325i wrote:Holy shit! All these 2.7's and such small gains!

Hey,the 2.7 is about torque,not bhp,it's torque that fires you out of a bend,or up a mountain,in a higher gear than a 325... using less fuel..

oakey wrote:Daimlerman has a 2.7 with an eta bottom end and a 320i head and it makes about 175bhp? and 180+ftlb? Cliffybabe is using a 325i head and his car puts out pretty much the same power.

180lbft?!

bss325i wrote:

oakey wrote:Daimlerman has a 2.7 with an eta bottom end and a 320i head and it makes about 175bhp? and 180+ftlb? Cliffybabe is using a 325i head and his car puts out pretty much the same power.

180lbft?!

thats at 2000rpm though, and peaks at just over 190lb-ft not too shabby for lugging around.

2.7/2.5 = 1.08 so a 2.7L in theory "only" provides an increase of 8% and in practice less at the topend if nothing is done to help breathing.

To the OP there is one way to find out and thats to try it......the 885 head outflows the 731 one but has bigger ports so in theory you might gain some low-mid and lose some top by using the 731 head but unless you have a baseline dyno you aren't really going to know for sure. Remember the biggest bottom end that the factory fit 731 head to was only 2.3L.

As for the 323i cam being bigger it may just be a myth until someone properly measures the two side by side. If i had one i would send it off to get done.

the squish given by the 731 head on a ETA makes alot of difference.
I´d run it on a ETA engine with a 320i, 323i or 325i cam.
It´s all going to be better then a 320i, ETA and will give favorable drivability over a 325i.

IIRC, when I bought my eta/731 2.7 from Iain, he said that it made over 180bhp/185lb.ft with the standard 731 head. It's now running 325i valves and the inlet ports have been increased to 325i size. TBH I'm not that bothered what it's making - what ever it is it's good enough for me.
At the end of the day it all depends on the accuracy of the dyno you run it on. Power and torque figures are just bragging rights down the pub, aren't they? It's the way the car drives that counts......

Gunni wrote:It´s all going to be better then a 320i, and will give favorable drivability over a 325i.

http://wp1016621.wp027.webpack.hosteuro ... f00080.htm

Use babelfish to translate it.
It´s a documentation of 2.7 setups using various means.

If it´s got 2,5 valves now I think it should be alot stronger then a 2.5, but the strangled exhaust port will always keep the powerband down unless if it was a Alpina head.

bss325i wrote:

oakey wrote:Daimlerman has a 2.7 with an eta bottom end and a 320i head and it makes about 175bhp? and 180+ftlb? Cliffybabe is using a 325i head and his car puts out pretty much the same power.

180lbft?!

mine made 194lbft

looking to go onto uniq soon though

bss325i wrote:Holy shit! All these 2.7's and such small gains!

thats what i was thinking barry...

e30bmlover wrote:

bss325i wrote:Holy shit! All these 2.7's and such small gains!

thats what i was thinking barry...

as already stated these are the cheaper 2.7 builds however im very pleased with my torq and responce of the car, The only reason i went 2.7 is due to blowing my bottom end

e30bmlover wrote:

bss325i wrote:Holy shit! All these 2.7's and such small gains!

thats what i was thinking barry...

Fair point considering they don't make much more than a good 2.5.
But how many 2.5's do you know that pull hard from less than 2k rpm? The useable torque is what an eta 2.7 is all about.

cliffybabe wrote:

e30bmlover wrote:

bss325i wrote:Holy shit! All these 2.7's and such small gains!

thats what i was thinking barry...

as already stated these are the cheaper 2.7 builds however im very pleased with my torq and responce of the car, The only reason i went 2.7 is due to blowing my bottom end

The reason I did it was because the 325 lump was knackered and the car was a motorsport convertible so wanted to keep it M20.

I think that unless you get the parts really cheap you would be better off doing an M50 conversion.

chu346 wrote:

cliffybabe wrote:

e30bmlover wrote: thats what i was thinking barry...

as already stated these are the cheaper 2.7 builds however im very pleased with my torq and responce of the car, The only reason i went 2.7 is due to blowing my bottom end

The reason I did it was because the 325 lump was knackered and the car was a motorsport convertible so wanted to keep it M20.

I think that unless you get the parts really cheap you would be better off doing an M50 conversion.

True. I think on Sports and Motorsports an M20 should remain though.

As you can see from the graph with before and after the BTB2 was fitted to my completely stock 325i, it now makes a shade under 170lbft @ 2500 rpm and a peak of 194lbft @ 4000 rpm.

Not bad for a B25 eh?

My 2.7 was built with a 731 head with a 288 schrick cam, 6 branch, bbtb and a custom map by AMD.

It made 204.3 horsepower(164 at whp) at 5729Rpm and 219.6lb ft at 3968Rpm. This was just after the previous owner had it built by BMW.

I would personally like to see how these figures would compare to a 2.5 with the same goodies.

288/288 or 288/272?

i cant wait to get my cam sorted

bss325i wrote:288/288 or 288/272?

288/272

geoffrey wrote:My 2.7 was built with a 731 head with a 288 schrick cam, 6 branch, bbtb and a custom map by AMD.

It made 204.3 horsepower(164 at whp) at 5729Rpm and 219.6lb ft at 3968Rpm. This was just after the previous owner had it built by BMW.

I would personally like to see how these figures would compare to a 2.5 with the same goodies.

Good results,any idea of the cost of building? Any usable power below 2000rpm?

geoffrey wrote:

bss325i wrote:288/288 or 288/272?

288/272

Cool. Is the AMD remap a proprer remap of the Motronic or just a chip for the Motronic?

daimlerman wrote:

geoffrey wrote:My 2.7 was built with a 731 head with a 288 schrick cam, 6 branch, bbtb and a custom map by AMD.

It made 204.3 horsepower(164 at whp) at 5729Rpm and 219.6lb ft at 3968Rpm. This was just after the previous owner had it built by BMW.

I would personally like to see how these figures would compare to a 2.5 with the same goodies.

Good results,any idea of the cost of building? Any usable power below 2000rpm?

Do you really need power below 2000rpm?

bss325i wrote: Cool. Is the AMD remap a proprer remap of the Motronic or just a chip for the Motronic?

Was a propper mapping session on the rollers I believe. Like I said all the work was done by the previous owner. It's scary looking through the receipts folder...

It would appear a lot of money has to be spent to get decent gains. Just glad I wasn't the one doing all the spending!