Building a hybrid M42/M44 engine?

[Brian28]

I'm going to be sticking a race engine together over the next month or so, will be more a basic freshen up rather than taking everything to the limits due to budget. Rather than a straight M42 rebuild, does anybody know if an M44 mix and match combination of rods block pistons etc will give me a capacity increase or other power advantage? The crank must be the M42 one (series regs) but everything else can be swapped. I've not found a lot of specific info on these engines. Are the heads the same? I was hoping the M44 may have bigger valve diameter but it looks like they are the same. Any other advantages/disadvantages to using different bits, eg would M44 cams be better than M42 ones? They are a different part number, but I can't find any info on lift/duration. I can get heads skimmed and blocks decked if needed, otherwise everything will need to be swapped as is rather than being machined.

I've built M20 and M40 engines before, this is the first M42 I've worked with.
Thanks
Brian

[Brian28]

Ok ignore that, I've had a re-read of the regs and the block has to be standard as well (factory overbore only allowed) so looks like all M42 bottom end. If anybody has the info on the M42/M44 camshafts though that would be handy.

Cheers
Brian

[Royalratch]

I think M44 has revised valve gear but only for smoother operation and reliability and also has better torque.The only difference is the capacity increase of 100cc, otherwise the M42 has better bits as standard.

I would just bung a remapped M44 in and save the hassle - quickest route to cheap power and stay in regs.

[Brian28]

The engine block and crank has to be M42, pity as would be a very easy capacity increase. Paul (ShepsEvo3) will be doing a bit of RR mapping once I get the engine done, hoping to get down there this week for a "before" run on the rollers.

[appletree]

what race series is this for?

will be nice to see hat figures you get in the end

wish i'd have done a before and after dyno run

[Brian28]

TTRS, racing in class D with the likes of Golf Gti, Astra GTE, E30 325i etc, shares most meetings with PBMW where I have been racing until now. www.racingsaloons.com . The engine regs are pretty free so aftermarket cams, reworked heads etc are all Ok. Downside for me is that crank has to be original stroke and block is factory overbore only, otherwise would have been a cheap and easy capacity increase with M44 parts. Would love to go the whole hog with everything permitted in the regs but I'm looking on it as a budget build, half personal motivation to do more with less (great feeling to beat more expensive cars), half finance as business has really slowed down over the last six months so spending a lot extra on a hobby can't be a priority for me. Feel free to pass on any budget tuning tips