M43 valves in M20 head

[digger]

catcams seem to like some advance, i think they must have wide LCA and so need it to build some dynamic comrpession

[abit]

That's a pretty solid power number. What cam is that?

http://www.catcams.com/products/camshafts/datasheet.aspx?ENGINE_id=111&CAMSETUP_id=265

Dont forget this a euro dyno so crank estimation. Hp at wheel is 160

Jep, these are numbers on engine. But still, I think It's pretty ok for m20b28.

I will try to make some minor changes in exhaust/ adjustable cam sprocket, maybe engine will become more funny as It is :D

[digger]

Dont forget this a euro dyno so crank estimation. Hp at wheel is 160

[redlightpete]

That's a pretty solid power number. What cam is that?

[abit]

Anyone else do this?

I belive no :D

[mr2peak]

Anyone else do this?

[abit]

Cool bro. Keep us updated. Good job.

recently dyno'ed engine, don't know if these valves helped to gain more or even lose power :D but result is like this... about 6500 km's driven and all still looks good :)

[abit]

Its neat to see this done, but I don't see the value in all of this work? You add spacers which is more weight to lose 13 grams per valve.

wait, what? how these spacers can add moving mass for valve/spring if its at the bottom and does nothing to that :D

also modifying these valves and spacers was cheap as fck and easy to install, so why not?

[nando]

the spacers are on the bottom, they don't add to the valvetrain mass.

[downforce22]

Its neat to see this done, but I don't see the value in all of this work? You add spacers which is more weight to lose 13 grams per valve.

[Ether-D]

Cool bro. Keep us updated. Good job.

[abit]

ok, this mod is done, today was first drive with my fresly built engine, seems like its working fine :)
so... made spacers for valve springs (1,4mm), @ start


after some while :D


also valve stems were shortened, actually, talked about that with one local engine builder, he actually told that I maybe could not shorten them, because rocker eccentrics would compensate valve length, buuut then I checked this theory, and reality is that you just can't install rockers at all, becouse they wont slide on valve :D so removed 1,3mm


and there all together

[Northern]

you could run a fairly large profile reground cam with a reduced base circle and still get the eccentrics to be in range! The geometry would be quite good infact

I was waiting for someone to mention this.

There has to be a spring that would fit with these, although I still don't see a huge advantage. The cost of replacing more and more of the valvetrain to fit a valve that isn't supposed to be there is going to be close to just buying proper aftermarket valves or undercutting/back cutting the stock valve and living with the weight difference.

[Bullhead]

Actually,

this, IF everything else is stock. But if it's not, all bets are off. We muck up the
valve tip/rocker geometry all sorts of ways, and it doesn't seem to make a drastic
mess of the top end.

Ideally, the rocker is exactly perpendicular to the valve stem when the valve's half- way
open so that lateral forces on the guide are minimized. But if you're off a little bit,
forces don't go up much. Travel might, some, but since it's already sliding, it's not going
to be all that much different- since it's already sliding.
I think where you'd run into problems is if the sliding force wasn't initiated with movement-
as in, if the rocker was so far off that it was perpendicular to the stem when it initially contacted
it. THEN it might make a real difference.

But that's WAY off...

t

He is right on the money here imo, you would have to change the angle 20-30 degrees for it to impact where it settles on the valve tip and where it follows the camshaft.

[TobyB]

Actually,

will it tend to wear out the guides a bit more because the eccentric is not in the optimal location and causes higher lateral forces on the stem?

this, IF everything else is stock. But if it's not, all bets are off. We muck up the
valve tip/rocker geometry all sorts of ways, and it doesn't seem to make a drastic
mess of the top end.

Ideally, the rocker is exactly perpendicular to the valve stem when the valve's half- way
open so that lateral forces on the guide are minimized. But if you're off a little bit,
forces don't go up much. Travel might, some, but since it's already sliding, it's not going
to be all that much different- since it's already sliding.
I think where you'd run into problems is if the sliding force wasn't initiated with movement-
as in, if the rocker was so far off that it was perpendicular to the stem when it initially contacted
it. THEN it might make a real difference.

But that's WAY off...

t