Realisic Power Increase

[wrs 118]

I'm interested in what you think the realistic power increase you could achieve on a M50B25 engine. It's in an E36 1992 325i with a slushbox...

I'm told 40kW is fairly easy to add by doing the cams, porting, compression and rechiping the ecu. I have a quote for just under $2k (not including the rechip) to do all this and supply the head set up ready to go. This assumes I do the removal and refitting.

I see this as a good relatively cheap option as the engine doesn't look modified so easy to get a warrant... It's supposed to still be very drivable with increase low-rev torque, quite important with an auto. I don't want to change to a manual, - on a tight budget.

Any thoughts on what you'd do to get and extra 20-30%

[bmwsparkle 3]

uve really got to ask urself, is it worth it? and at the end of the day you still will have a 325i auto, why not sell and put that money towards a 328 manual or similar.

but yuh, dont leave out headers and exhaust, cheap and effective performance mod. would sound pretty ham with an auto, the porting wouldnt achieve a hell of a lot with the stock exhaust manifold im thinking.

[wrs 118]

Thanks for your thoughts.

The stock 325i is quoted to be 141kW. Achieving over 180kW with the mods listed is supposed to be easy. While adding headers should improve the performance, it's a lot of effort and cost for a very small gain plus it looks modified. It's always something to add later.

The auto in this car has recently been rebuilt and isn't at all bad. In sport mode and with the kicker switch you can pretty much get a manual type response...

My friend has a 328 and it's bugger all quicker. We're pretty much side by side off the mark with the 328 only just pulling away, - they're not that much quicker. His is a manual as well.

Other options like turbo and supercharging etc don't have the same appeal due to both cost and certification issues.

I suppose my question really is do you think +40kW is realistic doing only cams, porting, raising compression and rechipping?

[conrod 1]

I'd say whoever told you you could get 40kw from those mods is being rather optimistic.Get a guarantee in writing before handing over the readies.The 325 (NZ)touring car had much less power than this, with more mods.Also, it is unlikely you will increase torque by much, usually porting and cam changes REDUCE torque at the bottom end of the rev range.And as these engines already start with quite high compression ratio, you would be a brave man to go higher. Interesting to note, the 328 and early 325(yours) were both rated at 192 hp, only the torque was different.

[Guest Andrew]

in the states people have had luck doing such mods to the m52 2.8 - purely because that motor is so choked from the factory. Even then - they get around 30 hp increases.US "m3" cams - software etc

would expect a manual and auto 328 to get a good pull on you from a standing start - they have an awesomly flat torque curve which is nearly higher at all points than the 325s. Perhaps your friend can't drive?

Supercharge it.

[wrs 118]

Yeah, the 328 does have better torque at low RPM and mine is a bit flat until around 2500 rpm but considering you're in first gear for about 1 second and below 2500 rpm for less than 1/2 that it makes sod all difference off the mark... From 0-100k's the 328 is 2-3 car lengths in front - not that signifiacant in distance but very significant in effective HP... The cam change proposed is a combination of lift and duration change. It's supposed to increase low RPM torque with a larger increase at the top end.

Thanks for your thoughts, - I was a bit worried the kW claims were a bit inflated...

I will ask for a guarantee.

Supercharging would be great but it would shag the auto in about a second...

Yeah, I know - use a manual box... I've been driving auto's for a while now (since giving up racing) and unfortunately have started to like them. Must be getting lazy.

[Jimocles 0]

cheap and easy Fan Delete mod, I havent dyno'd it since I did it

but supposed to be worth 6hp. had no cooling problems since I did it either.

[*sic 1]

get a honda if you want power y0

[m325i 705]

get a honda if you want power y0

and to be seen!

[cainchapman 0]

2-3 car lengths over a 0-100 run is quite a bit.

From experience, I can tell you that a 2-3 car length lead as I change into 3rd (100kph approx) on the drag strip is being beaten by 2 secs at the other end.

The Scooby ran a 12.6. (N.B. *sic, I haven't been beaten by a Honda yet)

40kW sounds very do-able. As you can get 200+kW from an S42 if you chuck enough money at it. Conrod is right, for 2 grand, you are not much chance at all.

[Ghost 0]

Quick answer: No you wont get 40kw (not with cams that don't sacrifice bottom end anyway...). The 2.5 is quite efficient (unlike the 2.8, which like Andrew noted, is restricted and can easily make significant horses relatively inexpensively).

I'd start with airbox, chip and exhaust before I considered cams. While the breathing is ok, whats the point of new cams if you dont free up some more air first?

Ash

[Guest Andrew]

i would ditch the stock ECU also - but then again we are getting into large money.

[westy 614]

I agree with everything

(cept the bit about hondas)

[wrs 118]

Thanks everyone for your input.

I went back to the company promising the 40kW increase about a guarantee.

They said they would only offer a guarantee if they fitted the head and timed the cams themselves. I said great, how much. Their response was 'Sorry, we don't have time to do it for ages". Effectively looks like they're ducking for cover on a guarantee... I felt as if I never got a satisfactory answer to any of my questions to then anyway.

So, it looks like headers and air cleaner first then...

Next I'll look at cams, porting and ECU reprogramming.

Once it's completed I'll look for a manual box as I expect the Nissan slushbox to fall out on the road not long after it's all going!! It's already gone bang once.

Cheers.

[318 g ride 0]

I lick honda crack! and love it!!

(and how!)

Edited January 23, 2006 by *sic

[bumpstop325 0]

hondas lick crack!

easy noob. know how we roll before dissin honda's.