Author Topic: Cam swap - Intake cam on exhaust side (Read 12720 times)

Leo_328i · « **on:** October 24, 2010, 05:59:05 AM »

Hey guys,

After doing a lot of trawling through bimmerforums, a common mod for M50NV engines is to get a spare intake cam and replace the exhaust cam with it.

Apparently its a good performance mod despite the fact that the cam specs are the same for both intake and exhaust - perhaps the specs are wrong?

Does anyone know if this is possible or has been done before on an M42?

Would be pretty awesome if this was a cheap cam upgrade mod for M42s!

Cheers.

deekay · « **Reply #1 on:** October 24, 2010, 06:19:11 PM »

i looked into this as well, but abandoned the idea when someone reported to me that the specs were the same.

if you feel like it, you could get a regrind for the intake side and then let us know if swapping it over to the exhaust made any further difference... but you'd have to do it in 2 parts for the results to be meaningful.

Leo_328i · « **Reply #2 on:** October 25, 2010, 08:25:29 AM »

The thing is that the cam specs for both intake and exhaust are the same for M50NV too yet there seems to be some sort of benefit in doing it.

Wouldn't be up to getting my intake cam reground - I had a mate put cat-cams on and it didn't ran really shit with his stock chip. It obviously needs a retune but the costs just add up too much and its not worth it for me as the 318iS is my DD and an E36 328i is my weekender!

If I could get an M42 intake cam for cheap somewhere and give it a go, that would certainly be worth a try!

deekay · « **Reply #3 on:** October 25, 2010, 02:12:18 PM »

another thing i never thought to look into when i was researching this the first time-

the e30 and e36 versions of the M42 intake cam have different part numbers.

e30 part: 11311727137
e36 part: 11311734118

(i also used realoem to check euro vs US, because the euro m20b25 cam is "sportier" than the one we got here in the states... however, for the m42 they are the same on both sides of the pond.)

unfortunately, without having someone sitting down and manually degree all 4 available cams (intake and exhaust side for e30 & e36 versions), it's pretty much a shot in the dark as to which would have the most aggressive profile- the e36 version could be "improved", or it could just as easily be a "torquier" grind spec'd for the heavier car. and yeah, just because the internet says the cams are the same specs doesn't make it necessarily so... this applies to both M50 and M42.

swapping the intake cam over to the exhaust side works on some VW and Nissan engines as well, which is why i started wondering if it'd work on the m42.

& yeah, you'd definitely want a chip remap to go with a regrind, if you were to go that route. i've got a 91-oct MarkD chip, as well as the dbilas ITB setup, and i've got a 4-1 header coming soon, so it could be worth it for me to try a regrind on the intake side...

i'm guessing you're in the UK? you could try asking around e30zone to see if anyone has/knows of a spare m42, or has upgraded their cams already... would love to hear results if you try it.

1998ccc · « **Reply #4 on:** October 25, 2010, 03:16:09 PM »

This site show the M50NV cams to be different In vs. Ex. Don't know if it is accurate.

http://www.usautoparts.net/bmw/engines/m50.htm

deekay · « **Reply #5 on:** October 25, 2010, 05:04:49 PM »

wish that site had a similar page for the M4X engines...

http://www.esatclear.ie/~bpurcell/318isengine.html#techinfo_engine
reports inlet 252 exhaust 252 Lift: inlet 10.2 exhaust 10.2

http://www.jannousiainen.net/hobbies/bmw/e36_318is/year_2006.htm
reports "242 degree / 9,2 mm lift" for his e36

all i've been able to find, but from above it looks like i guessed right... e36s have both more conservative cam grinds and the DISA system to haul around the heavier chassis.

also found this with a google search, which contradicts the above...

http://m42club.com/forums/showthread.php?t=5652

apparently Boyracer found lift to be identical, and couldn't tell a naked-eye difference on duration. i was hoping we'd dig up something i hadn't discovered before, but it really doesn't look like there are any gains to be had playing with stock camshaft combinations.

1998ccc · « **Reply #6 on:** October 25, 2010, 05:49:33 PM »

I "think" the information below is factory literature. The M42 240 deg / 9.7 data is the same as the M50 NV intake cam which makes sense since the engines are so simular.

http://www.motortraders.net/groups/group.asp?group=1&menu=89

The camshafts rotate in five bearing journals and are lubricated from internal cylinder head oil passages. The relatively short opening duration of 2400 combined with high valve lift (9.7mm) ensure good torque characteristics. The camshafts are of a hollow cast design for weight reduction.

flyinglizard · « **Reply #7 on:** October 25, 2010, 08:04:51 PM »

I found them to be the same specs. I dont have any later cams . But the 91 cams are the same to each other. The VW 16 cams are not the same.
MM

Leo_328i · « **Reply #8 on:** October 25, 2010, 08:35:31 PM »

Cool research guys,

I found this on M50NVs which claims that its a load of BS:

http://forums.bimmerforums.com/forum/showthread.php?t=1116523&page=9

Apparently the cams cant actually be swapped in an M50NV? Maybe it will apply to M42s too seeing that the engines are basically from the same family.

Haha mate, I'm actually from Australia, not England. Spent 6 months in the USA earlier this year and I'm yearning to go back ASAP. Loved Cali!

Leo_328i · « **Reply #9 on:** October 25, 2010, 08:45:31 PM »

Quote from: 1998ccc;97924

I "think" the information below is factory literature. The M42 240 deg / 9.7 data is the same as the M50 NV intake cam which makes sense since the engines are so simular.

http://www.motortraders.net/groups/group.asp?group=1&menu=89

The camshafts rotate in five bearing journals and are lubricated from internal cylinder head oil passages. The relatively short opening duration of 2400 combined with high valve lift (9.7mm) ensure good torque characteristics. The camshafts are of a hollow cast design for weight reduction.

I think this is definitely the most credible piece of literature out there on the M42 cams.

Funny that when the M50NV became the M50TU (VANOS) in 1993 they switched from the 240 / 9.7mm cam to a 228 / 9.0 cam as the VANOS could compensate for the loss in duration and the engine was able to produce the same peak power and have a fatter torque curve.

dude8383 · « **Reply #10 on:** January 10, 2011, 09:48:23 AM »

Curious if anyone has tried this...

dsm2002 · « **Reply #11 on:** January 11, 2011, 02:07:34 AM »

While this does not actually answer the question, I had some discussions with catcams about swapping inlet and exhaust cams. The specific issue I was chasing, assuming a start point of a 290/275� setup, it is possible to later buy a 298� inlet cam and move the 290� from inlet to exhaust.

Catcams advised that the only difference is the angular position of the cam lobes. This means that the factory tool cannot be used during the installation. If you time the camshafts using a dial gauge / lift at TDC, the swap should be no problem.

Boyracer · « **Reply #12 on:** January 12, 2011, 03:00:10 AM »

Quote from: dsm2002;100342

Catcams advised that the only difference is the angular position of the cam lobes. This means that the factory tool cannot be used during the installation. If you time the camshafts using a dial gauge / lift at TDC, the swap should be no problem.

I can confirm that factory tool or similar method is no good with non-original cams... I had shrick copies (256/10.2mm) timed just like originals and car did not run very well on low revs, it stalled a lot while reversing etc.

I think reason was because there was too much overlap, works a treat on high revs but kills bottom end power. So anything else than originals and you should time the cams with dial gauge etc.

I have measured E30/E36 M42 intake/exhaust cams and lifts are identical on all and I suspect so are cam profiles.

e30guydownunder · « **Reply #13 on:** January 12, 2011, 06:39:38 PM »

Any chance of you setting all the cams up in an engine with a degree wheel on the crank and measuring them boyracer? That is the only true way to determine whether any / all the cams are the same.

pdxmotorhead · « **Reply #14 on:** January 13, 2011, 01:33:23 AM »

Call around to local machine shops and find one with a gadget called a Cam-Doctor. Way faster than using a head. Last time I had a cam checked it was like 25 bucks.

Lift and duration are not everything, ramp time and lobe shape matter too.

Dave