1990 E32 Engine

Reiu1

Newbie
Points
51
Location
Germany
Car
90 BMW 735i E32 EU
So I have the luxury style E32 EU spec only BMW 735i. Its an inline 6 NA Fuel Injected. The engine in it is depressing. I did some research on the car and this one website said its supposed to have 210 hp and 305 torque. My parent's sienna has more get up and go than this thing, and its twice as efficient. This thing is chugging 30+ liters/100km while accelerating at a snails pace. The scale only goes up to 30.

I did notice a huge improvement of about 5 seconds with my thermostat though, but even then 0-60 is still 14 seconds. I replaced the broken one with an aftermarket 75C as opposed to stock 80C, Autobahn speeds driving and an old car, overheating. There is also an aftermarket K&N box filter. New spark plugs last summer. I did have to run the engine without a thermo for two weeks if that could do any dirtying.

I think there is a rattling tappet or valve on one of the forward cylinders, but the engine runs fine at al speeds, no quirks pop up at certain rpms. its kind of like a clicking sound. Could a loose tappet or valve be that detrimental to efficiency?

What I am wondering is how much of a difference new injectors would make for their cost, if I should get those fancy spark plugs that are 40$ a pop that promise a larger spark, replace pistons with high compression, maybe just spend some for a turbo or super?

Im even thinking about an engine swap, the bay is so huge I could fit almost anything in there, but I am reluctant to do so, inexperienced for one, but it does have a nice roar when it gets up to 6000 rpm, even if it does chug half the tank of gas.
 
Last edited:

billyo

Track Warrior
Points
167
Is it the long gearing and really heavy bodyweight holding it back. You should get more power out of an engine that size. The guys on here will have some tips for you but it would be worth exhaust, induction kit and a remap. Is it serviced and running well?
 

Reiu1

Newbie
Points
51
Location
Germany
Car
90 BMW 735i E32 EU
I dont know what remap means, but as exhaust and induction kit goes, what should I look for? bigger, smaller?

Anything I can do about gearing?

If it comes down to putting in new transmissions, would one of the newer (92) trnasmissions work for just fitting into place? even if its used? (german autodumps are bountiful in used bmw parts)

You know, I dont think a timing check has been done on it for awhile. Its never stalled on me for the 8 months Ive owned it.
 
Last edited:

Sid447

Torque Junkie
Points
272
Location
TRNC
Car
VX-Series 2 V8 M6
This is the old M30 straight-six.

They are a very strong (as in durable) engine and ceased production about a year or so after this model.
They were rated at around 210hp and 230lb-ft tq.
A very low state of tune and they last forever if they are looked after.
They were replaced by the M60 V8 engines of 3.0 and 4.0 litres which eventually grew to 3.6 and 4.4L The 4.4 was subsequently enlarged to 4.6 and more recently 4.8L


Yours sounds like it has a serious problem. You would be better having it checked out and a (cranking) compression or leak-down check should put a finger on it as it shouldn't be burning that much fuel.
An injector clean wouldn't do any harm but get the engine running properly on all six cylinders before doing anything.
Magic claims for spark-plugs are just that. All you need are a set of good Bosch or NGK's.
Ignore wild claims for some branded spark-plugs or spark-plug wires. It's B/S.
Trawl the net and look for a company that has experience in BMW tuning they will show you the way to go with this.


e.g.] http://www.fritzsbits.co.uk/
 
Last edited:

Reiu1

Newbie
Points
51
Location
Germany
Car
90 BMW 735i E32 EU
Im doing a compression check and timing tomorrow, but what do you mean leakdown check? I believe there is an oil leak in the pan, but it hasnt been a serious problem, I find little beads of oil every once in awhile. The exhaust looks thick like I am leaking oil, but it doesnt have the smell. The coolant is not diluted at all either. Maybe a compression ring went and thats why I am leaking oil out of the pan?

The plugs are bosch, got them last summer, but I wouldn't doubt that they need to be cleaned and adjusted. What I recently found out was that the camshaft that is in there can be adjusted fairly easily, how I dont know. Is it just a screw behind each lobe? If it can be adjusted, would having the exhaust port remain open longer benefit? And any sure way of measuring how much larger to make the lobe without opening up the block?

Speaking of which, you said the engine is pretty sturdy, could it handle high compression pistons? And the ones it was replaced by, can those be easily retrofitted?

And another random question, I was looking through the car gravelot, and I saw the same cars, same components, but the engine and main components were mounted reverse. Actually, my car was the only one with the filter on the right instead of left, so maybe mine is flipped. Were those the newer engines that replaced mine? If so, what do I need to do to retro fit the used or lightly used ones?
 
Last edited:

Sid447

Torque Junkie
Points
272
Location
TRNC
Car
VX-Series 2 V8 M6
A leak-down check,

is done by pressurising a cylinder with air and checking how long it takes to "leak-down" (or hold compression) It's a more sophisticated way of doing a compression test.

Small oil leaks around an engine aren't necessarily a problem.

The only thing you can do to a camshaft to improve or change anything is take it out and replace it with one that has more duration or lift or both. They are not adjustable in any way.
The other six-cylinder engines you saw were a most likely a different series. M20 for example is a sohc six, much smaller and slanted to the right side. These were used in 3-series and 5-series from '84 to around 1992.
If it was a dohc six then this would be what replaced the M20. These were known as the M50 series which then became M52 then later M54.
The biggest of these engines were the M54 3.0 which would still leave you short of grunt in a big heavy 7-series.
The M20 and M50's are a different design entirely to your M30 series engine.

As an option the early M5's (up to 1988) used an engine very similar to yours, though it was 3543cc and not 3430cc like yours. Also it was a twin-cam (dohc) six that was rated at 286hp. If you can find one of those in good working order this would fit pretty much straight in. But they are very rare now.

Fitting any other six-cylinder engine would take a lot of work (time) and money to fit and get running properly and would probably cost you more than the car is worth.
You'd be better off getting your M30 3.5 engine running 100% properly. Once it is you'll be pleasantly surprised. It isn't the best for economy but it will perform a good bit better than it is at the moment, I think.

If you are struck on the 735i for a good reason then fine. But for better performance (and economy) than what the M30 engine offers you in this car, it might be worth looking for a 3 or 5-series car which would be a lot lighter than a 7-series by 100-300kgs.
In which case the 540i V8 would be the sort of thing to go for if you want lots of go and a nice comfortable interior.
 
Similar threads
Thread starter Title Forum Replies Date
A Engine Conversions BMW forums 0

Similar threads


Please watch this on my YouTube channel & Subscribe.


Top