E30 M3 engine rebuild - Options ??

[jb1]

I have an E30 M3 which I only use on the track and have managed to blow up the engine. Not sure exactly what, but I'm told that it will need a rebuild (Is at Racing technologies in SW London)

Have been given 3-4 options and not knowing a huge amount about M3's (as have only had it 3 months) or engines would appreciate some advice:

A - Rebuild engine as standard. 2.3, 215bhp, cost: 4k GBP

B - Buy a second hand engine. 2.3, 215bhp, cost: 2-3k GBP. (Cheaper but potentially less reliable? wouldn't want it to go pop again)

C - Rebuild with Motec ECU and stronger bits (as I said I don't know a huge amount about engines):2.3, 250-260 bhp, cost: 7-8k GBP. Am told that this will be reliable and good for 200hrs of track use or 100,000 miles.

D - Buy a 2.5 block and rebuild from this with Motec ECU. 280bhp with much more torque. 13k GBP. (Not sure I'm really considering this option due to cost)

Many thanks for any thoughts you guys have, Jason

[chippy17]

I am sorry to hear about this, unusual for an S14 to go bang, what happened?!
I have recently sold an M3 Cecotto, which was looked after by RT for almost 4 years and they are great with these cars so you have gone to the right place.
I had my timing chain changed and head rebuilt with them and the job they did was expensive but perfect, afterwards the car was running the same power and more torque than it did when it was new!!! That was 95k miles later!
As for what to do I honestly cannot say, IMO I would edge towards a standard rebuild as it is always better to have the engine number matching the car. I know they will do a good job there, get Illias to do the work as he is the expert!


>> Edited by chippy17 on Friday 26th August 09:24

[jb1]

I was just running round bedford and the engine cut out. Never a good sign when you are driving along. I pulled on to the grass and to my suprise it restarted but was down on power and made a clanking noise.

Am probably erring towards option C. Would the extra 40bhp make a big difference to this car?

Thx, Jason

[Sleep Envy]

jb1 said:

A - Rebuild engine as standard. 2.3, 215bhp, B - Buy a second hand engine. 2.3, 215bhp, C - Rebuild with Motec ECU and stronger bits :2.3, 250-260 bhp D - Buy a 2.5 block and rebuild from this with Motec ECU. 280bhp with much more torque.

I've edited your text to keep it simple but I doubt you'd get that much power from the tuned 2.3 or 2.5 engines as the standard power units are running pretty much at the edge of their capabilities. Motec is a good idea as it removes the AFM breathing restriction but it's really expensive method to gain an additional 25 bhp.

B maybe the cheapest option but who's to say it won't go pop 6 months down the line?

C or D does sound tempting but how long are you going to keep the car for bearing in mind the cash you spend on modifications is rarely recouped when you come to sell.

IMHO I'd combine options A & C, rebuild the original engine but do the simple things like port and polishing, get the balancing done, change the cams for slightly hotter versions and then get it properly re-mapped on a rolling road. You should be able to realise around 230/235 bhp and achieve it a cost far cheaper than option C. The additional benefit is that you'll be keeping original numbers too.

[chippy17]

Sleep Envy said:

jb1 said: A - Rebuild engine as standard. 2.3, 215bhp, B - Buy a second hand engine. 2.3, 215bhp, C - Rebuild with Motec ECU and stronger bits :2.3, 250-260 bhp D - Buy a 2.5 block and rebuild from this with Motec ECU. 280bhp with much more torque. I've edited your text to keep it simple but I doubt you'd get that much power from the tuned 2.3 or 2.5 engines as the standard power units are running pretty much at the edge of their capabilities. Motec is a good idea as it removes the AFM breathing restriction but it's really expensive method to gain an additional 25 bhp. B maybe the cheapest option but who's to say it won't go pop 6 months down the line? C or D does sound tempting but how long are you going to keep the car for bearing in mind the cash you spend on modifications is rarely recouped when you come to sell. IMHO I'd combine options A & C, rebuild the original engine but do the simple things like port and polishing, get the balancing done, change the cams for slightly hotter versions and then get it properly re-mapped on a rolling road. You should be able to realise around 230/235 bhp and achieve it a cost far cheaper than option C. The additional benefit is that you'll be keeping original numbers too.

wise words above, what he said, you can always do the mods at a later stage
my opinion on these caes has always been: you are never going to get the kind of power gains that are possible with say a turbo engine, why not concentrate on suspension and brakes, if you can brake and go round a corner faster it will equal power gains, these cars were never about straight line grunt.

>> Edited by chippy17 on Friday 26th August 15:08

[pentoman]

Perhaps a more 'out there' option, but are there any other (BMW?) more modern engines that can make similar/more power, perhaps with more torque, and weigh the same or less?


Russell

[shortshiftin]

You can get a 2.8 or even a 3.0 from an E36 M3 into an E30 engine bay... not sure about the 3.2 but then I wouldnt want the VAnos headache... Id go for the 3litre from an E36 m3 and eat everything alive on the road!!

[jb1]

Very good idea thanks but the racing tech guys are telling me this is a very expensive option and the E36 engines are heavier and will affect the balance of the car.

Don't supposed anyone knows of an engine for sale?

Prefably new / rebuilt 2.5?

Thx, Jason

[sharkfan]

I know you've said that sticking a larger engine in is not something you're considering but both Alpina and Hartge have done it to E30 M3's - both of whom know what they're doing when it comes to modding BMW's.

The Alpina B6 3.5S had the standard 3.5L engine from the 635, whilst the Hartge had a tuned version of the 3.5L engine from the M1/M5/M6 putting out 330bhp and 262lb/ft of torque!

I understand that both cars had uprated front suspension to deal with the extra weight and I would imagine that you could find out quite easily what sort of set up was used.

Anyway, just a thought...

[M3 Mitch]

Perhaps the most important thing is to figure out what exactly went wrong with your motor. I would vote for a stock-ish rebuild with no corners cut, add an oilpan baffle since you track the car, but otherwise stock, if you plan to keep the car a long time.

Otherwise the used motor, and you can go down a middle path here of at least looking at the rod bearings, put in the oil pan baffle, etc. The shop may be able to perform a leakdown test on a motor (not as informative when cold but maybe better than nothing) before you commit to buying it.

What commonly kills S14 motors, judging from what I read on S14.net, is 1 detonation and 2 oiling issues with the big end of the rods. Antidote to #1 is get best grade fuel, keep the cooling system up to snuff, avoid over-aggressive chips. Antidote to #2 is to use a good oil, (I think Mobil 1 is damn good cheap insurance for any S14 and would not consider Redline overkill at all in a track car) make dead certain your sump is full or maybe a bit over for track use, and avoid sustained RPM over 7000. The bretheren on S14.net seem to agree you are in the clear at 7000 or under, but somewhere between 7000 and 8000 the oiling issue is likely to raise it's ugly head...the problem is you only find out your engine's ultimate RPM tolerance by exceeding it...

The more I think about it, a used engine with careful inspection of the more critical components (big end rod bearings, cam chain, add the oil baffle) is likely your best bet.

Hardly need to mention that you will put in a new clutch (chance to upgrade here too, and for a track car I would) throwout bearing etc. (so if your clutch was half worn, you could deduct half the cost of a clutch job from your repair bill as maintenance you had to do anyway, if it makes you feel any better..)

[cptsideways]

Stick a 3.0 or 3.2 M sport lump in or even a combination of the tow apparently, delete the vanos & you'll have a reliable 300bhp+.

Speak to John or Ben at Zoom at motorsport in Northants, I'm sure Ben might even take you out in his Drift spec "M" 316 stripped out 4 door astonishingly fast!!.

[rlk500]

Personally I wouldn't contemplate sticking the "wrong" engine in the car. If you ever want to sell it, I think you will have problems. Additionally, one of the features of the E30 M3 is it's balance and it's razzy 4 pot screamer. Good suspension, tyres and setup are enough to embarass a lot of "quick" cars at track days.

I suspect you have suffered the dreaded spun bearing. Not uncommon, but certainly not a week spot of the engine. For track use you need to overfill to halfway up the first bend in the dipstick.

I terms of what to do, unless the block is toast I would salvage what you can from the engine and have it rebuilt. I would expect it to come with a guarantee if the company doing it are worth their salt so you will be far better off than going down the second hand route. Save your money on Motec, and spend it on cams and a good custom map and setup, with a fresh engine you should see around 230/240bhp which will be totally reliable and easily enough for good progress (remember you don't need to slow for corners with an e30....)

HTH

[chippy17]

rlk500 said:

Personally I wouldn't contemplate sticking the "wrong" engine in the car. If you ever want to sell it, I think you will have problems. Additionally, one of the features of the E30 M3 is it's balance and it's razzy 4 pot screamer. Good suspension, tyres and setup are enough to embarass a lot of "quick" cars at track days. I suspect you have suffered the dreaded spun bearing. Not uncommon, but certainly not a week spot of the engine. For track use you need to overfill to halfway up the first bend in the dipstick. I terms of what to do, unless the block is toast I would salvage what you can from the engine and have it rebuilt. I would expect it to come with a guarantee if the company doing it are worth their salt so you will be far better off than going down the second hand route. Save your money on Motec, and spend it on cams and a good custom map and setup, with a fresh engine you should see around 230/240bhp which will be totally reliable and easily enough for good progress (remember you don't need to slow for corners with an e30....) HTH

must reiterate and agree, you best option is to rebuild your original engine, also with RT it would certainly come with a guarantee.

[jb1]

Cheers guys

There seems to be a consensus forming here.

I think ideally I would find a newly rebuild 2.5 engine, but back in the real world I will be rebuilding my 2.3 with a bit more bhp (as it is rude not to, now that it is broke)