Author Topic: What is the best factory inlet manifold? (Read 5531 times)

martin347 · « **on:** April 15, 2009, 01:58:52 AM »

There have been various inlet manifolds come out the factory on the m42 and m44. Which do you all think is the better flowing?
Also what size throttle body is best for a highly tuned m42?
Interesting to see everyones views on this!
Cheers, Martin.

xwill112x · « **Reply #1 on:** April 15, 2009, 06:36:22 AM »

best throttle body?
oem

second best?
ITB's!

JoeDellio · « **Reply #2 on:** April 19, 2009, 02:19:56 AM »

Howd this get three stars?!? I have noticed with the various M42 intake manifolds that they are all designed the way they are to fit around/work with the way the rest of the engine is layed out.

martin347 · « **Reply #3 on:** April 20, 2009, 01:53:45 AM »

Quote from: JoeDellio;70374

Howd this get three stars?!? I have noticed with the various M42 intake manifolds that they are all designed the way they are to fit around/work with the way the rest of the engine is layed out.

But do you think they all flow the same? I doubt it! So which one is the best? They may have been shaped originally to suit that models engine bay, but that doesn't mean they can't be retro fitted between the models.

1991 E30 M42 · « **Reply #4 on:** April 20, 2009, 11:26:33 AM »

the intake and exhaust manifolds flow fine, the big airflow limitation limitation on these engines are the cams, get you a set of Cat or Schick cams, and if you want to save some money, Delta does regrinds for $85 a cam i think

martin347 · « **Reply #5 on:** April 20, 2009, 12:19:27 PM »

Quote from: 1991 E30 M42;70426

the intake and exhaust manifolds flow fine, the big airflow limitation limitation on these engines are the cams, get you a set of Cat or Schick cams, and if you want to save some money, Delta does regrinds for $85 a cam i think

Yes, I agree with everything you say. I have a set of regrinds in and its made a load of difference.
This is 'by the way' though, there must be someone out there who has tried more than one inlet manifold and has an opinion on which one flows best!!

xwill112x · « **Reply #6 on:** April 20, 2009, 01:40:01 PM »

the stock one, thats which one.

martin347 · « **Reply #7 on:** April 20, 2009, 02:05:41 PM »

Quote from: xwill112x;70433

the stock one, thats which one.

Which one? Stock e30? What makes you say that? Have you tried any others and not seen an improvement?
Thanks for your reply's.

xwill112x · « **Reply #8 on:** April 20, 2009, 03:54:17 PM »

Stock e30, but it you just want more low end, An e36 manifold will help there. Some people use them in boosted applications.

What makes me say that?

Because what company in their right mind would take the time to R&D a new manifold for a older, out of date car? On top of that a 4 cylinder, it's like putting a fart can on a honda in many people's opinions.
If i were you, i'd spend my cash where it counted, not on a manifold that costs out the ass, for not even 5bhp.
If you want more power, and you've done all the basic mods, and don't want to do serious motor work, save your cash for a m50 swap.

1991 E30 M42 · « **Reply #9 on:** April 20, 2009, 05:16:18 PM »

get the manifold extrude honed, port match the upper to the lower and the lower to the head, cut your valve guides, polish the ports, knife edge and polish the tb, put a big set of cams in it and call it a day

martin347 · « **Reply #10 on:** April 21, 2009, 02:02:05 AM »

Quote from: 1991 E30 M42;70449

get the manifold extrude honed, port match the upper to the lower and the lower to the head, cut your valve guides, polish the ports, knife edge and polish the tb, put a big set of cams in it and call it a day

Yes, this is what I am planning, I am just trying to find out which manifold is best before I go to all that trouble.
I already have a 1960cc bottom end with 12:1 compression, running DTA, pushing out 172 BHP, with a set of mild road cams. I'm now building the top end to suit and have already ported the head and had the valves three angled.
The rally regs I run under say I can only use standard throttle body/plenum chamber. So that rules out ITB's. But what is the best inlet manifold made for the m42/m44?!

1991 E30 M42 · « **Reply #11 on:** April 22, 2009, 01:58:21 AM »

i don't think there is anyone on here that has tried the different ones, you ought to go to the junk yard and pick up one from an e30 and e36 and experiment, then report back with your findings

martin347 · « **Reply #12 on:** April 22, 2009, 02:00:26 AM »

Quote from: 1991 E30 M42;70555

i don't think there is anyone on here that has tried the different ones, you ought to go to the junk yard and pick up one from an e30 and e36 and experiment, then report back with your findings

Sounds like a good idea. I'll post up here what I find.

kowalski · « **Reply #13 on:** April 25, 2009, 01:37:45 AM »

the e36 m42 one is variable length, so i would want to say that that is better because it is built for low end and top end.

however, i do not believe that the e36 m42 manifold will fit under an e30 hood.

1991 E30 M42 · « **Reply #14 on:** April 25, 2009, 09:53:53 AM »

lower the engine a bit