Engine swap weight distribution

[96cali]

That's the motor I contacted you about back in April. If you're serious I'll see if they still have it. Does not have the cams or intake which you sound more than capable of doing. I'd love to have it but realistically ain't gonna happen for me soon and this one is practically at your back door.

[xxxJohnBoyxxx]

Originally Posted by 96cali

That's the motor I contacted you about back in April. If you're serious I'll see if they still have it. Does not have the cams or intake which you sound more than capable of doing. I'd love to have it but realistically ain't gonna happen for me soon and this one is practically at your back door.

Don't need the cams since I would want turbo cams with no overlap. PM me how to contact them. I think they were in Tampa right?

[campaiar]

Speaking from experience, upgrade the front struts, springs and (optional) sway bar to M3 components when you do the swap and drive the thing around all the curves you can find.

< 2 minutes later you won't care about weight distributions.

(I can't comment on changes for the track since my TI will never see one while I own it)

[xxxJohnBoyxxx]

Originally Posted by campaiar

Speaking from experience, upgrade the front struts, springs and (optional) sway bar to M3 components when you do the swap and drive the thing around all the curves you can find.

< 2 minutes later you won't care about weight distributions.

(I can't comment on changes for the track since my TI will never see one while I own it)

Already have a canidate for this motor: a light E36 318is model so it's all set up ZF trans, Medium LSD 3.23, 9# flywheel and LTW pressure plate. Suspension is alligned for drag racing but it still corners like on rails. This one would get the a turbo...

Option #2 ~ Purchase another BMW coupe of the 318 version and install the Metric with turbo in that car or just find a light E36 I-6 coupe with blown motor and good body and make that the donor car for the alloy motor with big Garrett GT40 on it, and leave the Metric car alone

Decissions...decissions

[pnosker]

I recommend the ti. The semi-trailing arm suspension, once effectively trained, can be killer on a track. That's why Z3M coupes always dominate in the same class on a track. There's a ti in NJ for ~$1000, needs a lot of tlc (some dings in the body and stuff) but it would be a killer track car. Has a good motor too.

[96cali]

Originally Posted by pnosker

I recommend the ti.

Plus then he would actually be cool like us. Ti or ban John!

There are cheap e36's all over. Tomorrow morning there's a 96 318i in the Goodwill auction.

[J!m]

Hey guys.

Just thought I'd chime in here on a few weight distribution and handling items that have been brought up.

I want to break it into two seperate items, necause the lines are being blurred a bit (which is reality of the situation, but bear with me).

1) Weight increase (overall) and it's placement.
2) Handling charecteristics of a "nose heavy" car.

When you do the engine swap, you are installing a heavier engine. However, what no one here has mentioned is that the I-6 sits further back in the chassis than the I-4 does. Some weight is already moved backward. Remember our basic machine: the lever. A small change in position changes the dynamics more significantly that you might think.

Also covered in my swap manual that no one mentioned is that the front wheels can be moved forward about an inch. Now we have a longer, more stable wheel base and essentially reduced weight on the front wheels because it is transferred to the rear wheels. (we changed the lever again)

The M3 front suspension includes 'caster tops' which increase caster quite a bit. Pushing the wheels forward using my method also increases caster further. More caster is more stable at speed. My suspension is VERY stable over 100 for extended periods. You don't do this on track, but I'm just mentioning it for thoroughness.

Relocating the battery is not essential to good handling. in a more powerful car, 50-50 static is NOT ideal. You want to be a bit nose heavy because the weight transfers under acceleration. This is why you spin if you lift going into a corner too fast. The weight transfers forward and you loose traction in the rear, so it comes around. Everyone had done this in driving school 101 day one...

The lightweight flywheel (strongly suggested) easily offsets the bulk of the rotational mass increase of the "two extra cylinders" of the six over the four. And I do understand the concept; however the M engines (really all BMW engines) are very well balanced for factory engines that the increase in piston reversal inertia is not so significant at the relitively low RPMS these cars operate at. For every piston at TDC there is one at BDC as well- balance. At 8K+, you certainly have to watch it closely, if for no other reason to keep the pistons from flying apart. It is a gyro, that is true, but the impact of the 6 gyro over the 4 gyro is small. You don't notice it in my car.

Weight of brake upgrades is a concern; however it is UNSPRUNG weight. Which, is bad in general (and I will not go there right now), but does not come into the chassis dynamics because (if your suspension is good) the brakes, spindles etc. stay on the road while the body (sprung weight) is listing side to side. Overall weight of the car will be higher; however dynamic weight does not increase so much when it is in perspective. Bottom line: you need to stop, so you need better brakes. Keep the weight you have/must have LOW in the car. Take out the passenger seat and mount the battery there if you are loosing sleep over it.

In summary, the problem is not as 'bad' as some have made it out to be. If the suspension and braking systems are upgraded as strongly suggested in my manual, you will have a very fun, safe and easy to drive car that will carve corners with the best in the world. Ask anyone who has one that is set up properly- they'll tell you the same story. Just get in and drive. You won't be at all concerned with these trivial arguments!

[xxxJohnBoyxxx]

^^Well said Jim. I have a new view on the subject now. Thanks for the insite

[J!m]

No problem John.

This is just the tip of the iceberg but I hope it put a few basics into perspective.

Also if you do happen to over-steer a bit, you can now apply gentle pressure with your right foot and square up the car with ease. The 1.9 is not so good at pulling off that trick...

[campaiar]

Originally Posted by J!m

In summary, the problem is not as 'bad' as some have made it out to be. If the suspension and braking systems are upgraded as strongly suggested in my manual, you will have a very fun, safe and easy to drive car that will carve corners with the best in the world. Ask anyone who has one that is set up properly- they'll tell you the same story. Just get in and drive. You won't be at all concerned with these trivial arguments!

Sounds oddly familiar.....

[J!m]

The dude abides.

[ti3]

Another question... I scanned through and I don;t think it was covered... whats the weight difference of the S50 vs the others? I assume its similar to the M50 but I dunno, if anyone has info on that I would appreciate it. THanks

[J!m]

I don't have exact numbers; however I beleive them to be within 100 lbs or less of one another. It depends on accessories attached more than anything else; the block is the same, the heads are the same, most of the components are similar (I think even the 2.5 and 2.8 have hollow cams as the M3 does).

So, the only huge advantage is the aluminum block Z3 motor. If that was built up with an M3 top end and a re-map of the DME it would be a pretty serious motor... (it cannot be bored to 3.2 due to bore coating)

[stevenwrichards]

Just re-read this thread for some reason and, as always, J!m is awesome.

Except now I want an aluminum block Z3 motor ...

[dynagroove]

Great read! I wish I could comment on handling with a stock ti vs. one with a swapped motor, but I've only driven the latter. The suspension on my car is stock and absolutely clapped out. In the coming months, I plan on doing a complete refresh of the front and rear plus new shocks and struts. I don't think I have the need or desire to go with a full coil over system. My plan was to go with the Bilstein sport suspension with the H&R sport springs (Turner package).

After reading the difference in weight & rotating mass, I'm questioning this. Will the H&R sport springs for the ti be enough, or should I look to get M3 H&R springs up front? I don't have the M3 brakes up front, but it is painfully obvious that this is a must for this car, so I will be going that route in the future.