Cam question

[M20_TURBO]

I'm working on building a 2.9 liter m20 and was wondering which cam to go with. There is quite a difference in the price between a reground, new billet and Schrick cam.

I don't want to run anything more then a 272, just wondering about the disadvantages of the stock reground cam.

[NI_racing]

i have seen that a reground cam will lower your compression ratio, but at the same time i heard that the machinist should add material to the cam before regrinding it to prevent thast from occuring.... Oh and the regrinds are cheaper.... but thats all ive heard. Lemme know what you find out, i'll be traveling that road soon myself

[whodwho]

i have seen that a reground cam will lower your compression ratio, but at the same time i heard that the machinist should add material to the cam before regrinding it to prevent thast from occuring.... Oh and the regrinds are cheaper.... but thats all ive heard. Lemme know what you find out, i'll be traveling that road soon myself

I would change your source for information...

[NI_racing]

yeah you cant believe everything you read in a forum. If you know, id love to be corrected.

[asubimmer]

i have seen that a reground cam will lower your compression ratio, but at the same time i heard that the machinist should add material to the cam before regrinding it to prevent thast from occuring.... Oh and the regrinds are cheaper.... but thats all ive heard. Lemme know what you find out, i'll be traveling that road soon myself

cliff notes:

I heard something from someone. Idk if its true but I'll spread it anyway. Hope it works out for ya!!

[Mitch M]

I'm working on building a 2.9 liter m20 and was wondering which cam to go with. There is quite a difference in the price between a reground, new billet and Schrick cam.

I don't want to run anything more then a 272, just wondering about the disadvantages of the stock reground cam.

NA or turbo? NA 2.9 needs way more than a 272 for a hp peak much above 5K.

[Knockenwelle]

The cam is your last choice in the build. You need to determine what you're doing with the head, what you want the static compression to be (fuel availability...), where you want your power and torque peaks, how you want to use it and for how long (life expectancy), and your available budget before considering camshaft choices.

[M20_TURBO]

NA or turbo? NA 2.9 needs way more than a 272 for a hp peak much above 5K.

Well, my car is turbo already but not very reliable with the ETA bottom end so I decided to upgrade to 2.9 liter and forged internals.

[M20_TURBO]

The cam is your last choice in the build. You need to determine what you're doing with the head, what you want the static compression to be (fuel availability...), where you want your power and torque peaks, how you want to use it and for how long (life expectancy), and your available budget before considering camshaft choices.

The head is going to see a mild port job and gonna have the valve seats redone. Also running a short runner intake manifold.

The reason I want to go with a bit more lift and duration on the cam is just to let motor breath a little more especially since the displacement is more then stock. I don't want to go any more then 272 because it is a turbo motor and I don't want to have any over lap and since I'm looking to make no more then 450hp I don't think I need anything more then that.

This is the intake manifold I'm using


Here is a picture of the exhaust port that has been gasket matched, thinking about doing the same to the new head. The head I'm using now has got some score marks on the cam and cam bearings.

[Knockenwelle]

That's more like it. But still, how will the car be used?

As far as what type of cam to run:
Like with rods, get the best you can afford. Stock regrinds will have rocker pad geometry issues, which may or may not become mechanical problems but will always cost you in terms of accurate and correct valve motion. They will never attain the performance level of a better cam. You are also trusting a (unknown?) cam grinder to get the profile right and to make sure it's indexed correctly. Unless metal is added to the lobes, you will need larger eccentrics to make up for the smaller base circle. Worthless, unless you're on a Starving Student budget. But you're building a turbo M20, and thus can't be THAT broke. Stock regrinds are also not guaranteed to have perfect bearing journals.

Get a Schrick, and put all your fears to rest. 272 sounds appropriate for a drivable, mostly-sane turbo motor with a small bump in anger. Lemme guess, planning for about 15 psi? If it was stock displacement, I'd recommend you use a stock i cam (256 deg).

[digger]

The cam is your last choice in the build. You need to determine what you're doing with the head, what you want the static compression to be (fuel availability...), where you want your power and torque peaks, how you want to use it and for how long (life expectancy), and your available budget before considering camshaft choices.

Cam is not the last choice......... how can you possibly choose the static CR without knowing what cam you are using. The camshaft has a significant effect on the cylinder pressures the engine sees and you need to account for this.

[Knockenwelle]

Camshaft IS the last choice. You can put together a damn good idea of what you WANT to build, but until you have the finished head flowed and CC'd, do some math, check P-D clearance and pocket depth, and evaluate valvetrain parts, you better not place the order for a cam. Proper selection is far too dependent on other motor parameters to pick before anything else. You might have to change duration figures when the flow numbers come in, change split dependent on I/E flow ratio, add or subtract overlap to account for a tuned header or ITB/custom intake, or alter the lift to fit piston selection. And then degree it, of course.

[M20_TURBO]

That's more like it. But still, how will the car be used?

As far as what type of cam to run:
Like with rods, get the best you can afford. Stock regrinds will have rocker pad geometry issues, which may or may not become mechanical problems but will always cost you in terms of accurate and correct valve motion. They will never attain the performance level of a better cam. You are also trusting a (unknown?) cam grinder to get the profile right and to make sure it's indexed correctly. Unless metal is added to the lobes, you will need larger eccentrics to make up for the smaller base circle. Worthless, unless you're on a Starving Student budget. But you're building a turbo M20, and thus can't be THAT broke. Stock regrinds are also not guaranteed to have perfect bearing journals.

Get a Schrick, and put all your fears to rest. 272 sounds appropriate for a drivable, mostly-sane turbo motor with a small bump in anger. Lemme guess, planning for about 15 psi? If it was stock displacement, I'd recommend you use a stock i cam (256 deg).

Well the car is basically a summer toy. I want it to be reliable and make decent power.
I didn't want to pay for the Schrick name, if I could get the same results from a reground, which BTW IE claims then that for me was worth it.
I am putting quite a bit of money into the bottom end so I don't mind spending a bit on the head espesially when most of the power a motor makes is dependent on the head.

[nando]

stay away from regrinds

I would look for something from catcams, especially with the euro being so weak. I beleive their 284 is pretty similar to a schrick 272.