inlet valves / solid lifters etc

[tim_s]

hey guys, anyone on here fitted larger inl valves or solid lifters etc to their m42? am interested in peoples' experiences, am vaguely considering going to 34mm inls on mine.

[nickmpower]

how much good would that do with the exhuast already being a bit samller then the intake?

[bmwman91]

Revving beyond 7200RPM is not really possible for the M42. While swapping in solid lifters would take care of the over-pumping problem in the lifters, the crank damper is only good to like 8000RPM. Oversizing the valves could help a little I suppose. Once again, I would imagine that some software changes are necessary to fully realize the gains.

[asubimmer]

8k would be awsome

[kowalski]

is that gear thats on the balancer a part of the balancer?

[tim_s]

Revving beyond 7200RPM is not really possible for the M42.

rubbish!!!

the crank damper is only good to like 8000RPM

so why is 7,200 rpm your magic number?


Oversizing the valves could help a little I suppose

with the standard valves on a 1.8 you can rev over 7,200rpm.


I would imagine that some software changes are necessary to fully realize the gains.

I'm running megasquirt.


why do you think the vib damper is an issue? I've heard this rumour before, but find it hard to believe, especially as i know of e30 m42s with the standard damper running over 7,200 rpm consistently with no ill effects. there's a guy over here trying to push the limits of a spare m42 he has with a custom chip burned for it, so that he can find potential weaknesses for his turbo project. ok so he's being extreme, but the point is that his engine is still going, and will comfortably rev over 7,200rpm. btw a standard-ish car with the same map has achieved 170bhp at the flywheel on the rollers :D (its not exactly daily-driveable though!)

i've come to the conclusion that the condition of the rubber is probably more likely the issue than the damper design at such a specific rpm. do you have any pics of damaged engine and of the damage caused etc., or is it just speculation on your part? i have never heard of any damage caused this way, only rumours. my standard engine had a rev limit of 7k and was fine for ages too.
anyway, if it is proved to be a potential issue, its so easily sorted its just a complete non-issue to me. if you can give more details, i'll consider swapping the crank pulley for the revised one, until then i think it's staying. i've examined its condition quite carefully and its fine. in relation to all the trouble of changing inl valves, lifters, fuelling, bottom end, tbs etc, suggesting that the vib damper is a show stopper is mad!

also bear in mind that as i'm running a 2.1, its not just for v high rpm that i'm interested in increasing the inl valve area - i'll be moving a lot more air than standard anyway. i'm not sure that i'll t be going over 7k ultimately anyway - mb 7,2k, i'll just have to see how things go once its built.


how much good would that do with the exhuast already being a bit samller then the intake?

exh valves are frequently smaller than inlet valves (all bmw engines for example) as inl valves are much much more critical to power output so the trade-off is worthwhile, and the m42 exh valves are certainly plenty big enough (same size as s54, for example - s54 = 105bhp/litre).

so, anyone any useful info relating to this?

[hamann318is]

I'm pretty certain you'll get valve float after 7.2k. It happens in the M50s with the hydraulic lifters.

[Febi Guibo]

would improved valve springs help? say like a high-tech beehive valve?? (if this is a sadly uninformed question, fire away)

[2002maniac]

The problem with solid lifters is that you need special camshaft profiles. You could use Euro S50 cams as a grinding master though.

DO IT. Whats a few more bucks?

[tim_s]

I'm pretty certain you'll get valve float after 7.2k. It happens in the M50s with the hydraulic lifters.
yeah this is a prob, hence the interest in solid lifters. i've never run an m42 at a high enough rpm for this to be an issue, so am not sure how severely this happens, its supposed to be light (i.e. not piston hitting bad, just loss of power bad).

srtonger valve springs will definitely help prevent lifter over-pumping, how much i don't know. hadn't really thought about this route, is def a good idea.


The problem with solid lifters is that you need special camshaft profiles. You could use Euro S50 cams as a grinding master though.

oh, interesting! what's responsible for this? i wonder whether the stock cams could be reground.

[Febi Guibo]

DO IT. Whats a few more bucks?

until now, words never before uttered in the (american) E30 community... let's record this historic moment! :)