bottom end rebuild questions...

[BDK]

I still have this 3.8L crank and was wondering if I could just rebuild the bottom end??

The Motor,which has 84K on it, checked out and leak down/compression tests were very good and instead of rebuilding the entire motor, I was wondering If I could just rebuild the bottom end to accept this 3.8L crank....maybe bore it out abit but leave the head alone, maybe a refreshening but not complete rebuild....
what do you guys think??

Just wondering because I would love a little more grunt off the line ....

[m535is]

Sounds good. It is definitely possible to do that, but you also should realize that you will probably want to start upgrading things like the exhause and the intake to be able to get the most out of the 3.8L

[Duke]

Just wondering because I would love a little more grunt off the line ....

Sorry Bro, you got a S38 and it will never have the grunt you want. 300cc more displacement is really not that big a difference. Now if you had a 426 Hemi, you would have some grunt!

Just enjoy it for what it is and make TCD develop a FI kit for the S38.

FWIW - My little old untuned M30 on a rolling start will spin the 255 tires in 1st to redline, 2nd to RL and into 3rd. Its got grunt..........ahhhh, but you know this. FI my friend.........FI.

[BDK]

Well,
I figured it would be you or Todd to say TURBO IT but that is not what I want....
Just a little more bottom end torque,

I really think 90mm stroke and little more bore could help this abit....

Will it be up to turbo numbers??
NO, but that is fine...

I don't have to be the fastest, I just don't want to be the slowest....

I still bet once I get this thing where I want it that I'll still kick your butts in the twisties here.... .....

You can have the straights and I 'll take the twisties....

[Duke]

You can have the straights and I 'll take the twisties....

I'll take both, thank you.

Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST! Get BOOST!

No boost, no balls

[Adam W in MN]

I can't comment for sure on what options a 3.8 liter crank will give you into an M30, but I will say that a bone stock S38b38 motor makes 295 ft/lbs of torque which is very healthy for a 3.8 liter, naturally aspirated motor even by today's standards.

Duke, what kind of 255 tires were these that you were spinning through 1st, 2nd, and part of 3rd gear? Not sure that I believe this unless it was rock-hard, old rubber. Well, I guess if you were finessing the clutch for a burnout I could maybe believe it. I think the numbers you quoted were around 260 lb/ft before you did the turbo.

My E34 M5 3.8 liter will spin the rear tires in 1st gear by stabbing the gas hard after you get going, but that's usually only when temps are 40 degrees or less and the ZR rubber is harder. This is with Kuhmo ECSTA 275/40/17 rears. Also I'm not sure if that speaks more about HP or torque since they start breaking loose really when the engine has revved beyond 4K rpm (the car is making 360ish at the crank).

Paul Cain did something similar to this using a custom stroker crank in his M90 "L" block engine. His website is 38csi.com or something like that (his E9 has been on the cover of Roundel before).

[Duke]

Duke, what kind of 255 tires were these that you were spinning through 1st, 2nd, and part of 3rd gear? Not sure that I believe this unless it was rock-hard, old rubber. Well, I guess if you were finessing the clutch for a burnout I could maybe believe it. I think the numbers you quoted were around 260 lb/ft before you did the turbo.

Michelin Pilot Sport PS2 tires. Believe it. Was a rolling start, boost comes on, tires spin. The shift were fast and hard so the engine stayed on boost and thus tires never got a chance to grip until 3rd gear. Was mid day in the high 70's as far as temp. No brakeing or clutch dumping to get the tire to spin. Once car is tuned I bet I can spin them into 4th.

[Skeen]

Adam,

Looks like some miscommunication. Duke is saying he can spin up the tires easily post-turbo--not on his NA motor.

[Adam W in MN]

Yep, just realized that when I read his response. Duke, I can totally believe it with the turbo, I thought this was with your motor before forced induction.

One of my favorite stories from Rob Levinson of UUC Motorwerks was when he used to own that Dinan stroker E28 M5 Turbo. He told me some punk in a tacky VW Golf GTI or something was messing with him. They both were in some traffic so he let some space build in front of him in the M5, got along side the punk, and at about 30mph stabbed the throttle to the floor. He said the rear end completely broke loose and a huge amount of tire smoke was left behind him. The kid had a look of disbelief on his face and Rob's comment that "wheelspin while moving really got his attention". Gotta have tons of torque to do that.

[Philo]

The last person I recall was Suzy....., some of the old timer board members may remember her. I think Bruce in Canada pissed her off on a weekly basis if memory serves..., being the only girl ever to own the fastest E28 M5 ever. I have that car's original exhaust on my car right now...., when I purchased the exhaust from Suzy it had a single pipe that split into two before going into the resonator....., man that pipe must be 4" in dia.

Great story.

Philo.
-----------