m110 bigger valves
 

good day

what are stock valve sizes for the m110 motor. How big can i go?

dont go for larger valves, go for larger pistons and cam retard ;)

im not really a fan of top end power jay. there arent very extensive roads in durban. its a mini town.

i really like quick acceleration.

take a look at this cylinder head. doesnt look like there is much room for improvement.

maybe the exhaust side. i wonder if it will be worth it. i dont plan on porting the head. just machine new seats for the bigger valves. dont want to kill the torque. what do you guys think

We need a more close-up view of one of the combustion chambers please.
Regards, Eric

my appologies. those pictures were of a US version. mine is a euro. i think the pistons are domed. i guess i will only know what room i have to work with when i take it apart and DO IT!

just want to know your opinion on my theory though. if i had to use the bigger exhaust valves and retard the exhaust cam timing by 2 degrees. will i lose the overlap? the only way i see the bigger exhaust valves being of benefit is a better scavenge effect with the cam overlap. but i have to retard the exhaust cam timing or else im going to be wasting gas at low speeds. is 2 degrees retard on the exhaust cam enough to lose the overlap effect? but then im just going to push the power band a tiny bit higher. agh to heck with it. might as well just work on a blower

We need to know what the stock valve sizes are to begin with. I know that on my M103 the exhaust valves are already too big in relation to what the intakes are. On my engine I would rather enlarge the intake valve as it is the limitation. (I think we talked about this when you were still a M102 man.)

As far as you messing with the overlap, again we need to know how much overlap you have to begin with before we can decide if you should be messing with it. I feel though it should probably be left alone and you should focus your attention on keeping your exhaust valve size approx 80% of your intake valve size. By doing that you won't have to worry about upsetting things so much that you'd have to mess with the overlap.

I agree that a turbo is a great option!
Regards, Eric

why do i have such a greed for speed anyway?

If you like quick accel and bottom end oomph, why do you want to increase valve size? If you increase valve size you'll just reduce intake air velocity and reduce your bottom end.

That very well may be the case but we don't know anything for sure until we know what his stock valve sizes are.
Regards, Eric

I believe the best upgrade for these engines is a free flowing exhaust. Much like the CIS injected Porsche engines of the same time period.

Make sure you have a nice clean exhaust flow and it should pay dividends at the top-end...but like MAG58 says it will hurt that low end torque.

Attached is a picture of the CIS heads and the spark plug location.
Only thing I could find was:
IN: 45.2
EX: 39.1

Engine Bore: 86.0mm
Engine Stroke:78.8mm

FYI, those are larger valves than a Porsche 911 3.2 engine had.

PS: Sorry for digging up an old thread, I saw it on a search.

It's OK! Dig away!
We needed those valve sizes!
Regards, Eric

thanks for that. the car came with dual 40mm exhaust.

i have removed the cat, upgraded to dual 50mm with an x pipe in place of the cat. yes, you are right, it comes alive in the top end. like crazy. hasnt lost too much low end torque, in fact it feels more powerful in the low end. doesnt pull through the revs like it used to, but feels more powerful. dont know if i sound funny,but some people will know what i mean.

working on the eaton m45 that i bought. just need a dump valve and intercooler. i have a friend that can fabricate the brackets and piping for me. rising rate fuel regulator already on there. cant wait.

cams are straight up. no overlap. perfect for supercharger.

Sounds good, so the CIS tricks for Porsche 911 engines seem to work on the M110 too.

I'm sure it doesn't feel like as much of a 'pull' through the revs because the curve is flatter.

Yep, the non-overlap of the CIS cams takes well to supercharging...just look at those Porsche 930 engines that ran CIS.

Do you have any links to any of those CIS tricks for Porsche 911 engines? I'd like to see if some of them can be applied to CIS-E engines too.
Regards, Eric

Here's what is typically done on a 911 engine:
Pelican Technical Article: Extracting Power from CIS 911s...

However they have the ability to use a lot of different cam profiles and pistons with different compression ratios.

First step would be to open-up or backdate the exhaust (if you don't have to smog the car). A free-er flowing exhaust does wonder on a 911 engine and may do the same with the M110.

Second would be a cam swap, but I've been unable to find a performance cam for the M110. I even wrote AMG to see about getting the specs for their performance M110 cam, but they didn't have documents on it (or didn't want to share...)

Third would be a compression ratio boost, but the M110 with euro pistons has good compression as-is.

Finally would be an ITB EFI system running on megasquirt controller or something. This could be done with wasted-spark ignition too. This would be the ultimate, but I have yet to see one on an M110.