Please help! 2.7 engine build spec, i'm confused!

[Simon13]

Rat are u pissed that post made no sense.

Look i'm not a millionaire nor am i the best. But i know what will help make a 2.7 tick

Neil i know i get on your tits and there is nothing wrong with 2.0 M20's theres just no point to them.

There are high power 2.7's with ETA cranks, stories of them breaking are not made up. It's just no one on here has suffered a failure yet! There is some truth in there i'm sure.

It's not about following the crowd! it's about going the route that works, theres nothing wrong with following a method that works. These engines are old and ways of getting good power out of them are well documented.
There is nothing wrong with going this way. Do VeeDub boys get bored of bbs split rims? Proper 2.7's are a hoot to drive and still a quick car even now.

The difference between a 2.5 and a sorted 2.7 is like night and day no lie

If u follow what the hartge, alpina and racing dynamics did fairly closely u can't go far wrong. with a few modern bits like standalone ECU's,MAF and proper synthetic oils youre just helping the cause.

[rat]

He, He,

Yes Simon, I was ever so slightly pissed.


What I ment to say was I'm not an engine builder by trade although I have built a few.

My first one - I fitted the scraper rings upside down on the pistons and I clipped the oil control rings because they seemed to big.

It was quite interesting on start up cue immediate rebuild.

I also applied for a job with Mountune (Dave Mountain's business) as a tech but was turned down - probably for the best

It's not about following the crowd! it's about going the route that works

You're not wrong there - It really depends on what you want from an engine

[M5pilot]

A standard 2.5 vs a well tuned 2.7 - massive difference, you wont want to drive the 2.5 ever again.

Highly modded 2.5 -

MAF Conversion/Stand Alone
284/272 Schrick Cam
BBTB
BTB/Racing Dynamics 6 branch Manifold

This lot has shown to give 190+ BHP and up against a well tuned 2.7 the gap is closed considerably.

A 2.5 with this spec will start pulling away from a st 2.5 quite easily.

After this lot, if you feel you want more then do a 2.7. Atleast you'll have all the expensive tuning bits sorted.

[M5pilot]

If you guys want something to aim for, aim for around 180-200bhp at the wheels. That at the Flywheel would be between 215-235bhp.

Now that kind of figure makes an E30 damn good fun to drive!

The Silver C2 will be making an appearance again at Aces soon. That had 180bhp at the wheels last time it was dynoed. Just as a comparison, a 215bhp model M3 makes around 170bhp at the wheels. That doesnt imply the C2 has 225bhp before anyone starts!

(Sorry for quoting BHP at the wheels, it just makes more sense as this is the power actually transmitted to the road/wheels)

[Ant]

2.7 is so old school it hurts

[M5pilot]

The 2.7 vs 2.5 turbo challenge is yet to be done!

[M5pilot]

Does make alot more sense to stick a much better engine in rather than piss about with an M20.

S38 is also a very good way of getting monster power into your E30. A typical 3.6 engine will only cost around £1500 now. 315bhp to play with!

Its apparently lighter than the S52 aswell.

[Chaos]

For £1000:

-A 325i or 525e block. It doesn't matter a toss which you use.
-Six 325i pistons - buy some used ones or a cheap short engine from JonB.
-The standard 525e crank and rods.
-A 325i head. Don't bother with gasflowing.
-A decent cam kit. Piper are excellent, Schrick is similar but with a designer label and price tag your £1000 budget won't afford. Go for either a 270.......or a 285 if you can stand a slightly ragged idle. Neither require piston machining. The cam is the single most important part of your engine build. You can't imagine how tame the standard BMW cam is.

andy, what about the eta block (as it comes out of the car) and a 2.5 head.
how will that compare to the other 2 options u mentioned
and will there be a difference in compression between phase one and phase 2 heads?

[Ziggy]

andy, what about the eta block (as it comes out of the car) and a 2.5 head.
how will that compare to the other 2 options u mentioned
and will t here be a differencei n compression between phase one and phase 2 heads?

Bttt!
I cannae believe it'd be that simple, but if it is, I'm doing it!

[Ziggy]

You can screw a 325i head straight onto a 525e short engine and use Eta pistons. With a later Eta engine with the 10.2:1 compression you'll get a CR of @9.2:1. I've done just this and it works fine.

Nice one Late '85 on?
Current plan's to get another 325 head & a 525e (either to break or just the lump), slap em together with a new cam between, & then just swap lumps over a weekend! Well that or chop the whole thing in for an e34 m5 / 540i, but it's a bit sunny for that at the mo...

[DORAS]

hello everyone!

[u]the latest on the engine build!![/u]

what i have done so far:

sent eta crank 325 flywheel to be lightened and balanced.

block skimmed 1.5mm

head been skimmed.

bores checked and honed.

got hold of a set of m50 2.0l rods (apparently stronger and lighter)

325 pistons from a 89 model (checked the skirts clear)

I will be porting the head slightly and fitting a 272 cam. (do i need new springs etc??)

i have just bought a new 6 branch manifold. (need a cheap stainless centre box if you know where i can get one?)

fitted m50 24v 2.5 injectors (told they higher flow rate and can cope with up to 240 bhp)

all engine parts powder coated.

does this all sound correct??

I went down to fritz's bits yesterday to get manifold and they said i would have problems running standard 325 injection system?? told me i would need a stand alone system £Â£Ã‚£'s something about the timing etc due to the longer stroke. can you throw any light on this as i am struggling with the budget know?

regards rich

[Martinaston]

I've heard that before but if it's a longer throw on the crank it just means the pistons travel faster but 6k rpm is still 6k rpm

[Templ8e30]

I've heard that before but if it's a longer throw on the crank it just means the pistons travel faster but 6k rpm is still 6k rpm

True but if you think about it like this:

The mixture needs to ignite at a specific point in the stroke, say 5 degrees btdc. If the same timing is used on an engine with a longer stroke the piston will be in a different position in the stroke at that specific point resulting in incomplete or inefficient combustion.

Cheers,

Iain T