Cam and headwork

[DCColegrove]

An M20 (NA) Putting 220 HP to the ground is a lot...

Really, really a lot.

[z31maniac]

An M20 (NA) Putting 220 HP to the ground is a lot...

Really, really a lot.

Didn't you say when you added the eBay header yours put down 188, with stock displacement? I know you've done alot of other things, but seems if you applied those same techniques to a 3.1L you could near that number.

[DCColegrove]

Didn't you say when you added the eBay header yours put down 188, with stock displacement? I know you've done alot of other things, but seems if you applied those same techniques to a 3.1L you could near that number.

Yes, I wasn't so much disbelieving the number (even though I did miss the 3.1l on that) and didn't mean it to come off that way...

Just that that is a lot of RWHP...

The ebay header (like I said in that thread) is of very sound design... Just knocked off with cheap non magnetic rice alloy...

It is on a "stock displacement" M20B25... but that's about all that wasn't tweaked.

[z31maniac]

No, I got ya, it didn't come off wrong, I'm just curious based on the power numbers you were able to acheive with stock displacement, what you think is possible with it stroked to 3.1L. Which is a pretty healthy increase in displacement. ~approx 20%.

Taking a motor from ~167 crank to ~265 crank (guessing on like 19% drivetrain loss), is a pretty healthy bump without forced induction.

[nando]

An M20 (NA) Putting 220 HP to the ground is a lot...

Really, really a lot.

go look at the chart. it's a legit build up - 11:1 CR, S52 crank, aggressive cam, B2B headers (best there is for the M20 and $$$$), wolf V500 EMS and a worked over head. None of this $2500 stroker "kit" bullshit running motronic and an adjustable FPR to "tune" it.

[nando]

A 220 whp M20 would be insane and EXACTLY what I want!

Although I would think a well planned and well built M20 should be able to hit 200whp, which would be more than enough to have some fun in.

you could always talk to digger and try to copy his setup as closely as possible. It seems very well put together, but probably on the expensive side (the MM head and pistons weren't cheap!). On the other hand, budget strokers seem to be pretty much a waste.

nothing wrong with building a head and sticking it on your stock engine for now - that's what i did. I built the head first and built the bottom end later. Of course now I want to redo the head but I have no real need to. if it isn't broke.. :p

[nando]

No, I got ya, it didn't come off wrong, I'm just curious based on the power numbers you were able to acheive with stock displacement, what you think is possible with it stroked to 3.1L. Which is a pretty healthy increase in displacement. ~approx 20%.

Taking a motor from ~167 crank to ~265 crank (guessing on like 19% drivetrain loss), is a pretty healthy bump without forced induction.

19% is a bit optimistic. I'd conservatively estimate 12-15%. Of course crank HP doesn't really matter unless you've measured it on an engine dyno directly.

[z31maniac]

19% is a bit optimistic. I'd conservatively estimate 12-15%. Of course crank HP doesn't really matter unless you've measured it on an engine dyno directly.

less than I would have though on the parasitic loss

[TwoJ's]

Wow, a successful discussion in General discussion.

I too am torn about what to do motor wise. I am leaning towards staying m20 as well.

That is strange that they changed the bearings between early and late models. Any idea why they would do that? Production cost?

[TwoJ's]

Another question: I'm trying to find dyno graphs for real stroker m20's, and I'm not having much luck. I'd like to see what the curves actually look like rather than hearing the peak numbers.

Am I stupid, or just looking in the wrong place?

[nando]

less than I would have though on the parasitic loss

dyno operators will always quote you a bigger parasitic loss because the reverse calculated crank HP will be larger, making you feel better about the actual amount of power at the crank VS the wheels and thus more likely to come back for another pull..

[z31maniac]

dyno operators will always quote you a bigger parasitic loss because the reverse calculated crank HP will be larger, making you feel better about the actual amount of power at the crank VS the wheels and thus more likely to come back for another pull..

I was going off what I thought I remembered reading somewhere that healthy M20s put down in the 130-135whp range, vs 168 stock at the crank, which puts you at around ~20% drivetrain loss, right?

Or are the numbers off?

[z31maniac]

you could always talk to digger and try to copy his setup as closely as possible. It seems very well put together, but probably on the expensive side (the MM head and pistons weren't cheap!). On the other hand, budget strokers seem to be pretty much a waste.

nothing wrong with building a head and sticking it on your stock engine for now - that's what i did. I built the head first and built the bottom end later. Of course now I want to redo the head but I have no real need to. if it isn't broke.. :p

Hmmmm, wonder if there are any local guys worth trusting with a head to work on.

[nando]

I was going off what I thought I remembered reading somewhere that healthy M20s put down in the 130-135whp range, vs 168 stock at the crank, which puts you at around ~20% drivetrain loss, right?

Or are the numbers off?

dynos vary so much between each other that's pretty much an invalid statement. what dyno did they get 138whp on? what were the correction factors used, ambient conditions, tire pressures, fuel quality, maintenance?

Not only that, but there have been plenty of 150whp+ dynos of stock M20s, just follow the SpecE30 guys a bit (I'd say 145whp would be on the weaker side). But again, the same questions above apply here. And lots of them will use a big correction factor (like 20%) and say they are making 190 at the crank, stock.

Taking the quoted stock HP and using your latest dyno results to figure drivetrain loss, and then using that number to blanket quote crank HP from WHP measured on another machine with different variables is pretty useless.

The only thing that truely matters is getting a baseline of your engine as it is, and then going back to the same dyno later after you've done upgrades to measure the difference. Dyno plots from other engines are still useful, but mostly for the shape of their curve, not for the absolute peak numbers.

[z31maniac]

^I'm with you completely. My R6 saw extensive dyno time and tuning, so I know all that.

I was basically throwing those numbers out for "discussion's sake."