Tinkerputzer's 3.1L m20 stroker and e30 build (Update on post 64)

[tinkerputzer]

I checked my notes and MM sport cam came out around 110-111 LSA.

the sport lobe is supposed to be bigger than shrick 284 (rally and sport apparently have same inlet lobe) but measurements you did dont match up with this chart so who knows. short of having both cams side by side and plotting them out its a lottery really. i didnt like my MM rally cam except that it was smooth idle and excellent fuel economy

Yeah i spent a lot of time measuring the cams and got repeatable results for every checking height. I came to the conclusion what you get doesn't always match what the manufacturer claims or advertises.

So say my numbers don't match MM's exactly but since i measured both with the same method with repeatable numbers i think it's safe to compare them to each other.

Here are the numbers i came up with.

MM sport Intake:
Lift / Open / Close / Duration
.012 / 19 btdc / 66 abdc / 265*
.050 / -2 atdc / 47 abdc / 225*
.200 / -35 atdc / 20 abdc / 165*

Schrick 284/272 Intake:
Lift / Open / Close / Duration
.011 / 32 btdc / 72 / abdc / 284*
.012 / 30 btdc / 66 abdc / 276*
.050 / 11 btdc / 46 abdc / 237*
.200 / -21 atdc / 16 abdc / 175*

MM sport Exhaust:
Lift / Open / Close / Duration
.012 / 63 bbdc / 26 atdc / 269*
.050 / 35 bbdc / 4 atdc / 219*
.200 / 2 bbdc / 23 btdc / 154*

Schrick 284/272 Exhaust:
Lift / Open / Close / Duration
.011 / 70 bbdc / 22 atdc / 272*
.012 / 69 bbdc / 23 atdc / 272*
.050 / 48 bbdc / 1 btdc / 227*
.200 / 17 bbdc / 33 btdc / 164*

[nando]

what's the peak valve lift on the MM cam?

looks like what you'd expect - the schrick has more overlap and closes the intake valve much later (why it makes more top end power), and the MM cam has a typical wide LSA (better emissions).

personally I don't see that a 3.1l needs a lot more additional low end grunt - your motor makes more torque at 2000rpm than mine does at peak. the MM cam seems to fall pretty well flat on it's face which is too bad because there's no reason to be afraid to rev the engine to at least 7k.

[tinkerputzer]

what's the peak valve lift on the MM cam?

Intake / Exhaust
MM Sport: 11.86mm / 10.5mm
Schrick 284/272: 11.81mm / 11.25mm

personally I don't see that a 3.1l needs a lot more additional low end grunt - your motor makes more torque at 2000rpm than mine does at peak. the MM cam seems to fall pretty well flat on it's face which is too bad because there's no reason to be afraid to rev the engine to at least 7k.

Agreed, i have the revlimiter set at 6950/7000 :)

[LJ851]

This engine needs ITBs

[tinkerputzer]

Some day

[digger]

what's the peak valve lift on the MM cam?

looks like what you'd expect - the schrick has more overlap and closes the intake valve much later (why it makes more top end power), and the MM cam has a typical wide LSA (better emissions).

personally I don't see that a 3.1l needs a lot more additional low end grunt - your motor makes more torque at 2000rpm than mine does at peak. the MM cam seems to fall pretty well flat on it's face which is too bad because there's no reason to be afraid to rev the engine to at least 7k.

you cant tell which closes later from those numbers they have the same closing point at 0.012" and 0.050". its almost like the closing part is the same and the added duration comes from opening sooner which just increases overlap but usually you would get a midrange boost. i think the exhaust duration gives the topend gain. split duration cams are never going to make good hp unless the head is ported in a way that suits this. the exhaust port on the m20 is just not good enough out of the box to get away with low exhaust duration even with a good low back pressure and tuned exhaust.

in anycase from memory the rally cam was about 120 degree separation if not slightly more

i don't trust much MM says these days.....even when i had my head flow tested in 2008/09 it didn't live upto what they they claimed....i need to try and find the numbers several harddrive crashes mean i am not sure where it is. my next head flows atleast 20% more both inlet and exhaust and flow keeps going upto all the way to 0.700" so should be good for quite a bit more than 300bhp

[nando]

I'm pretty certain Schrick published their LSA figures for all the M20 cams, don't remember what it was off the top of my head though.

[digger]

I'm pretty certain Schrick published their LSA figures for all the M20 cams, don't remember what it was off the top of my head though.

they 284/272 is 110 iirc which is a good area to be in for that cam.
when you start adding duration you want to tighten it up unless you have alot more compression to avoid bleeding off too much pressure (DCR effect).

you need good headflow with a wide lSA and alot of duration since the operating rpm of the engine goes up and the head needs to flow well to match the higher rpm.

with the MM rally cam the power was biased to the topend but not really any higher than a traditional cam would provide and midrange suffered. even now my engine is extremely sensitive to exhaust changes and i feel it the exhaust port on the MM head which has less work done and small duration are the cause

[tinkerputzer]

Schrick advertises it as 284/272/110. The 110 refers to peak timing. Their definition of peak timing is this: Peak timing is shown as °Crankshaft and defines the angle between the gas exchange TDC and the lobe center line of the inlet or exhaust valves.

Back when i installed the cam for some reason i interpreted this as LSA which makes no sense because LSA is built into the cam and tells you nothing on how the cam should be installed. What it really means is um "lobe center" like it says. Don't know how i misinterpreted that but oh well.

Lets take my numbers from .050" to find lobe centers (they should be 110).

Intake: 11+46+180=237/2=118.5-11=107.5
Exhaust: 48+(-1)+180=227/2=113.5+1=114.5

Retard the cam by 3 degrees

Intake: 8+49+180=237/2=118.5-8=110.5
Exhaust: 45+2+180=227/2=113.5-2=111.5

The conclusion i draw from this is the cam was 3-4 degrees advanced when i installed it. So i guess when i dialed the cam in at the dyno i put back to where it should have been installed in the first place.

Digger you make me want to try a schrick 288/288. I wish schrick made a 284/284 though. So what is the actual advantage of a split duration cam?

[digger]

it gets more complicated with asymmetric lobes;) well a split cam should have slightly better idle, emissions perhaps bottom end etc due to less overlap but empirical data suggests that you choke the engine and end up with too much residual exhaust cause when it comes around to the inlet part of the cycle. usually you look at intake to exhaust flow %. its alot more complicated though anything to do with the exhaust is

i would look at a set of ITB that will give probably 20whp peak and give a much more useable rpm before adding anymore duration to the stock manifold

[dustyperez]

hey are the oil pan gaskets you used cork or rubber? if rubber where did you get them

[tinkerputzer]

i would look at a set of ITB that will give probably 20whp peak and give a much more useable rpm before adding anymore duration to the stock manifold

Makes perfect sense. Looking forward to seeing the dyno sheet that compares stock intake vs itb's on your old engine ;)

hey are the oil pan gaskets you used cork or rubber? if rubber where did you get them

Paper

http://www.rmeuropean.com/Part-Number/Oil-Pan-Gasket-__11131730234_MTC_CB4144DE.aspx

[digger]

my baseline was down on what it was at its best due to various reasons but it is apples to apples comparison. My stock intake is along way from stock to and was still alot better.

my PC died so will do it in next few days when i am up and running properly

[digger]

hope nobody gets their panties in a bunch over linking to the bad forum

http://www.e30tech.com/forum/showpost.php?p=1376852&postcount=111

[LJ851]

hope nobody gets their panties in a bunch over linking to the bad forum

http://www.e30tech.com/forum/showpos...&postcount=111

Awesome, digger. I would love to do the same on a built M30.