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

[LJ851]

This engine needs ITBs

[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 :)

[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]

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*

[digger]

Just referencing the cam gear index marks while at the dyno.

I'm not sure i think the schrick had more duration on the intake lobe than the mm sport. I wish i would have played with the timing on the sport cam while at the dyno just to see how it would react to changes.

I don't have it anymore but i did plot it. I'll have to look at my notes. I think we've had this conversation on another forum...

Thanks! It's doing well. Leaks oil like a pig though.

http://www.metricmechanic.com/pdf/M20-Cam-Comparison-Chart.gif

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

looking at only part of the picture (duration only) on paper can be very misleading

[tinkerputzer]

when you say advanced or retarded was the cam dialed in originally correct as per schrick specs? or was it just advanced or retarded from however it was first installed what ever that may have been?

Just referencing the cam gear index marks while at the dyno.

the MM sport probably more torque because the inlet lobe is alot bigger (more area).

I'm not sure i think the schrick had more duration on the intake lobe than the mm sport. I wish i would have played with the timing on the sport cam while at the dyno just to see how it would react to changes.

do you have the MM sport cam still? plot it out. i'm interested to see the LSA. the MM rally is very wide and wonder if the sport is the same

I don't have it anymore but i did plot it. I'll have to look at my notes. I think we've had this conversation on another forum...

Nice thread and car! I envy your skills.
Hows your wife's car doing?

Thanks! It's doing well. Leaks oil like a pig though.

[tak7]

Nice thread and car! I envy your skills.
Hows your wife's car doing?

[digger]

when you say advanced or retarded was the cam dialed in originally correct as per schrick specs? or was it just advanced or retarded from however it was first installed what ever that may have been?

the MM sport probably more torque because the inlet lobe is alot bigger (more area).

do you have the MM sport cam still? plot it out. i'm interested to see the LSA. the MM rally is very wide and wonder if the sport is the same

[dirtbag30]

i love reading threads like this. great job!

[tinkerputzer]

Thanks man! I wish i would have but i didn't know there was another option until it was too late.

[deutschman]

Great build! I love all the pictures and detail. I cant wait till I get to work on my next m20. I have only ever built an m20 head, but haven't had the chance to build a block yet. My next m20 will be a stroker, I already of the crank spacer lol
Why didnt you go for a brass pivot in the bell housing? Lasts a bit longer.

[nando]

The schrick curve looks better to me. The torque peak isnt as high but the power band is broader, and it makes more power overall.

Last time i did my timing belt, i put the cam back on too advanced, yeah, it was a slug!

[tinkerputzer]

Engine is still going strong. Have had a few issues but no show stoppers. This thread needs some updates i just need to take the time. Here are the dyno charts to hold you over.


Numbers in green are the MM sport cam. Numbers in yellow are the schrick 284/272.


This chart compares the schrick 284/272 to the mm sport cam

-blue dotted line is the mm sport cam
-aqua line is the schrick 4 degrees retarded
-orange line is the schrick 3 degrees retarded
-purple dashed line is the schrick 4 degrees advanced lol

It's amazing the difference a few of degrees of cam timing can make.

I'm really supprised the schrick didn't out do the mm cam in peak torque.

One thing to keep in mind is this is the same dyno shop as before with the same type of dyno but in a different bay and different dyno then before. Also the day the mm cam was dyno'd was about 30 degrees cooler than when the schrick was dyno'd.

[nando]

What did the cam and cam gear adjustment do to the torque curve?

[MR 325]

How she runnin'?!