Stroker 731 Head Specs Question

[g323]

I know strokers have been covered in length in the various e21/e30 forums. However, I have found very little info on people running strokers with 1) 731 heads, and 2) K-jet.

Please bare with me as these are not general stroker questions, I understand the concept and the advantages, Im wondering about the numbers of this specific setup.

My idea is to do all stock-ETA bottom end, 731 Head, K-jet.

I would like to know:

Probable horsepower/torque?

Compression ratio?

How would this affect my timing (Right now I have it at 22degree btdc)?

I have a newer ignition distributor(I believe from an l-jet 323i), should I use it with this setup

How would this effect the preferential octane gas to be used-compression will be lowered, so lower octane? or not lowered enough?

[m20powered]

The compression ratio will stay the same as with a 200 head, so if you use the usual 9:1 eta block then that's what you'll get. 87 octane will probably be fine.

22 deg... what RPM is that at again?

Should gain a lot of torque, with a modest HP gain if you're sticking with the old intake.

[AlaskaBimmer]

well my 2.7 bottom with a 200 series head with a hot cam (don't know what cam unfortuanatly, it woun't idle well under 1200 rpms with it) on kjet was 140 rwhp 161 torque. so you can expect somewhere in that range with that setup.

I have since ported the head and added larger intake valves so I might have a few more hp now, need to go redyno it....I posted a thread a couple of years ago with the graphs in it.

[g323]

m20powered
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The compression ratio will stay the same as with a 200 head, so if you use the usual 9:1 eta block then that's what you'll get. 87 octane will probably be fine.

22 deg... what RPM is that at again?

Should gain a lot of torque, with a modest HP gain if you're sticking with the old [COLOR=blue ! important][COLOR=blue ! important]intake[/COLOR][/COLOR]
.

1500 RPM

So the head doesnt effect the compression ratio? or your just saying that the 731 is the same size as the 200 and so it will be the same-that makes sense.

AlaskaBimmer
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well my 2.7 bottom with a 200 series head with a hot cam (don't know what cam unfortuanatly, it woun't idle well under 1200 rpms with it) on kjet was 140 rwhp 161 torque. so you can expect somewhere in that range with that setup.

I have since ported the head and added larger intake [COLOR=blue ! important][COLOR=blue ! important]valves[/COLOR][/COLOR] so I might have a few more hp now, need to go redyno it....I posted a thread a couple of years ago with the graphs in it.

You have the eta 200 head and you custom drilled some stuff right? did you change out the softer springs too? Ive heard that the ETA stock setup got 120rwhp and the 323i e21 stock setup got 140-maybe change out your springs? Do you have a website on your work? What kind of gas mileage do you get?

[joel323]

I have owned a car with this set up, the low end torque over the stock 323i is huge. I thought mine was about 170 hp with about 180 ft lb of torque. . which is in line with those rwhp numbers above. It had better low end torque than my 323i with a 2.5 i motor.

[m20powered]

Yeah the 200 and 731 heads have the same combustion chamber volume. 885 is bigger.

22deg at 1500RPM sounds like a lot to me (assuming I know anything haha), might need to back off a little.

Ive heard that the ETA stock setup got 120rwhp and the 323i e21 stock setup got 140

The stock eta is 121hp at the crank not at the wheels. rwhp is lower by roughly 15% because of drivetrain losses.

[AlaskaBimmer]

1500 RPM

So the head doesnt effect the compression ratio? or your just saying that the 731 is the same size as the 200 and so it will be the same-that makes sense.



You have the eta 200 head and you custom drilled some stuff right? did you change out the softer springs too? Ive heard that the ETA stock setup got 120rwhp and the 323i e21 stock setup got 140-maybe change out your springs? Do you have a website on your work? What kind of gas mileage do you get?

I have had extra oil holes drilled for the non eta cam since I'm using a 200 eta head. if you have a 323 head to start with you don't have the cam/spring issue. I have no idea if the springs were changed, bt I'm going to have to assume they were at some point. I got the car already modded as the motor swap was done in the early 90s...

on the Highway i clocked it at 20 mpg using a gps since my odometer has the broken gear problem I need to fix.

My 140 hp is rear wheel as stated, at the crank that would be around 170ish give or take a few, which is well over stock, and on par with the 325i motor, but with loads more torque.

[bam2002]

It looks like this thread has been quiet for a while. I see the terms 200 and 200 eta head being used.
I have 2 Euro 320, 6 cyl engines. I just had one of the 200 heads rebuilt stock. But I want to use the ETA bottom end. Rather than rebuilding the stock 2.0 engine, the parts are harder to get. I would rather use a ETA engine- bottom end. But I want to use the side Euro Distributer and a carb on the car.
WHy because I am building a e21 for the 24 hours of Lemons. I have a american e21 body with the correct 323 front crossmember. But I want to keep it really simple to work on - repair. So no Ecu. or FI.

Any suggestions.
thanks

[Henriquesbruno]

It looks like this thread has been quiet for a while. I see the terms 200 and 200 eta head being used.
I have 2 Euro 320, 6 cyl engines. I just had one of the 200 heads rebuilt stock. But I want to use the ETA bottom end. Rather than rebuilding the stock 2.0 engine, the parts are harder to get. I would rather use a ETA engine- bottom end. But I want to use the side Euro Distributer and a carb on the car.
WHy because I am building a e21 for the 24 hours of Lemons. I have a american e21 body with the correct 323 front crossmember. But I want to keep it really simple to work on - repair. So no Ecu. or FI.

Any suggestions.
thanks

Hey bro!!
I know its been 11years lol but did you end up thrying this setup?
Because I also have a 2.7 bottom end and a m20b20 carbed. So im wondering how the solex carb handles the extra displacement?