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how much power....roughly

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I have a new head coming my way with a schrick 289 cam, the casing is off of a 76 e21. I have a 38/38 carb but everything else is stock oem including the springs and valves on the new head. Can I expect a horsepower or torque increase with the new head?

thanks,

chet

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As I have learned so far on the M10, head/cam work usually does more for your higher rpm performance...helps it rev higher and breath better at higher RPM's. To get more torque usually you need to mod the block, and/or pistons. So you should see similar torque, but be freer revving and more higher RPM power. For example..before my new engine, I hit a wall about 4k RPM...it would continue to rev, but slow....Now my new engine revs all the way to 6500 fast....new top end...cam, 38/38 and headers.

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sounds good

what cam do you have?

do you have the wider intake inlet head?

thanks,

chet

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Chet, do you have flat top pistons? If so, you'll wind up with about an 8:1 CR. Not optimal for a performance cam. What head do you have right now, an E12 or the old 121? I think you won't lower your compression ratio by going from the E12 to the E21, but you will by going from the 121 to the E21

Do you mean a 284 cam? I haven't heard of a 289.

I don't think you're going to get too much increase. I've heard that the 284 in itself will give a very mild increase in top end performance, but certainly nothing that will cause you to say "oh wow!". In my opinion, I wouldn't go through the trouble unless you upgrade the pistons also, unless you need to pull the head for another reason.

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sounds good

what cam do you have?

do you have the wider intake inlet head?

thanks,

chet

I have a 284 cam and a e21 head. 9.5:1 compression ratio.

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Purely as a reference point, my old motor used a 38/38, a 292 cam, 10:1 CR, and a ported E12 head. It was dyno'd at 100hp at the wheels and 100 ft/lb torque. Given what you've listed, I'd guess you'd be a bit lower than this.

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Here is a second reference. I have a 2.5 M3 block, E12 head ported, stock cast-iron header, 304 cam. 10.5:1 compression with 48 DCOE's and on the dyno did 149 at the rear wheels. With more carb work I should have another 10+ hp.

I feel that this is all the power I or even you really need.

Norm

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Is your car a track or street car Norm??

Curious is to how it idles with that 304 cam....

(I'm thinking about building an m10 stroker instead of an m20 swap :))

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Here is a second reference. I have a 2.5 M3 block, E12 head ported, stock cast-iron header, 304 cam. 10.5:1 compression with 48 DCOE's and on the dyno did 149 at the rear wheels. With more carb work I should have another 10+ hp.

I feel that this is all the power I or even you really need.

Norm

Blasphemer.

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I use my car more for the weekend rally/auto-X, however this motor could be used as a daily driver. In addition to the mods to the motor there is also an aluminum flywheel and sport clutch. As for idle, I think it idles great.

But most importantly, it did not just throw a bunch of parts together. I spent $$$ at a machine shop having everything balanced together. Such as the clutch on the flywheel spun together on the crank. My motor is so smooth that when I rev up to 6500, I cant even feel it. I must look at the tach to remind me to shift.

Norm

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