engine and drivetrain How much power can the rear end take?

[lelio]

and what have people done when they needed to handle more than that? I've seen that you can do the 320 LSD swap which would be nice, but not necessarily stronger, especially since your still using the same cv joints on the outside of the axle.

the engine im putting in makes 200 hp but may get up to 300-350 in the next few years. There's gotta be people making that and more from m10's or various other swaps. What have you guys done?

Im gonna have to spend some money on a custom driveshaft and i don't wanna have to do it twice

[punchesdfw]

What engine are you putting in that makes 200hp?

[lelio]

nissan sr20.

keeping a journal with a little more info here: http://sil02.livejournal.com/

[ryanOC]

oh nooooooooo

[punchesdfw]

nissan sr20.

keeping a journal with a little more info here: http://sil02.livejournal.com/

My Mom says I can't be your friend anymore. LOL

[lelio]

yeah i figured there'd be some of that. after the response i got in this thread ;

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,271134/highlight,/

come on people, sacrilege can be fun! mother just doesn't understand me...

[BLUNT]

from reading your blog it doesnt appear youre scared of much. id think about fitting an e30 subframe with a medium case diff. it would have to be fabricated but youre going to need something different with those kind of numbers. a 320 lsd can take 200 if you dont get stupid but curtis breaks rear ends on a weekly basis with his turbo m20. i think hes upwards of 300???

[NickVyse]

I think the weakest links are the stub axles - you can buy billet replacements, but as Blunt said, you might be better off changing the whole back end if you're aiming for that kind of HP.

[wazzu70]

how much did the turbo M10s make? Im sure it really isnt a lot by todays standards. What do people with custom turbo M10s run? Do they just put up with the breaking? What breaks the internals, or the driveshafts? Sorry for all the questions.

[winstontj]

As I've been told by others when I asked similar tranny questions: It's not the HP that will break stuff it's the torque.

There are many factors that you've got to take into account when asking these questions. Tires and weight are the two single most important things you need to factor. #1 how heavy is your car? #2 do you have the grip / ability to really get those numbers to the road? Look at power to weight ratio theory. (this is exagerated) In theory, you can have 1,000,000 lbs of torque and HP and if your car weighs in at one pound you'll never break anything because you will be able to apply all of your power. You won't load things up because your car will accelerate, won't load up around corners, on hills, etc. This is how our cars race side by side many larger (both in displacement and weight) cars and are competitave. I encourage you to do some homework on this stuff before you go throwing a high HP BMW or Nissan motor in and start breaking things.

If you are breaking rear ends, driveshafts, axal splines, etc. think about this... If you lightened up your car the torque wouldn't load up as much and you wouldn't break stock parts, nevermind having to spend the dough on beefier stuff....

Just a theory

[wazzu70]

You can only remove so much weight....but yeah if you cant get that power to the ground what is the point of having it? Move the onset of torque higher up the rpm range so the car is moving before its heavily applied. Like mentioned this will apply more of the torque to scootin', rather than breakin' things.

Seriously, do people with turbo M10s continually break their diffs? if so at which point is the weak link. I ahvent really heard of this being a huge problem before? I guess I dont read enough .

[winstontj]

Nahh.... it's the turbo M20 dude that BLUNT was talking about. I've only read a few of the threads but that guy smoked like 5 2002 rear ends before he started looking at things like M5 or Ford/Chevy somethingorothers.... You BUILD and turbocharge an M20 you can put some numbers up. With the parts available you can easily have 300 at the wheels. 3.2L strokers (or more maybe) with a turbo or twin turbo now that's when you start breaking stuff!

The idea is to have the right balance of power for your car. Even if you were to bolt a chevy small block under the hood chances are you'd break everything under the sun because all you did is bolt in HP and torque, not design a system. Reality is that once you start digging into the 2002 as a serious project (unless you're Paul Cain... Paul Cain = AMAZING) you will find that there is a balance. Upgrade the powerplant evenly with the suspension, brakes and chasis and #1 there will be no need for a crazy HP bolt in forign-job motor, and #2 a properly designed M10/S14 (BMW 4-banger) will get you as far as your wallet will take you.

I promise this: It's a cost thing. You bolt in 300HP under the hood you're going to tear up your car - but you'll have 300HP for short money. If you want usable, drivable, functional power that you can put to the road and use, stick with an M10 or an S14 and go with suspension and brake upgrades. You'll run circles around any hacked up transplant with a broken rear end.

The 2002 turbo was 170hp out of the box better FI and bigger turbo gets you 230hp stock turbo motor. Now build a 2.3L stroker M10, add in headwork, intake, intercooler, today's FI and ignition systems and a massive turbo and in a year I'll tell you exactly what you'll have at the wheels without tearing up anything. (I'm expecting ~300 at the wheels)

[TJW]

A standard non lsd 2002 diff can take way over 200hp and can live with 300hp. but like anything else it can wear out.

If you hear somebody has stripped a diff then ask the question 'why' I think you will find that there is no history or possibly it has done a few miles down the road, a properly built 2002 diff will take more power than a m20 tubo can push.

If you are putting a Nissan turbo in then why not fit the rear end from the same car if you are worried about it,

[lelio]

thanks for your input guys.

so it sounds like the stock non-lsd diff might do ok with 200hp...

Probably only because the tires would spin before you could put that much force on it. and believe me im going to make the car as light as possible so yes that is a good point, less weight = less force, (sr20 is all aluminum block BTW) i could go the cheap route and have that just be my fusible link for the drivetrain.

the only thing im really risking is the price of having to make a different drive shaft if i find i need something different.

In the end i suspect ill have to put in something that ill have to custom fabricate everything on, I was just hoping to cheat on this one part of the car and maybe do something that someone else has trailblazed. I shouldve known better.

also i realize some of the points winstontj makes are valid, but i am going into it with my eyes open. Im bolting in a 200hp motor, not 300. its small and lightweight , it makes that hp stock so it should be reliable(ish ) fuel injected etc. . it seems like pretty "usable, drivable, functional power" to me . i threw out 300-350hp as something i wanna prepare for happening YEARS down the road because i realize the chassis will have a LOT of catching up to do before it's equal with even 200 hp. im working on brakes right now, and ill have to get new wheels and tires before its running and once it is running suspension will be the first thing i turn to , then there's a roll cage somewhere in the future for the usual reasons plus I dont know how much power the frame would take before twisting. im sure a billion other things im not thinking of, but ill deal with it, ive got time.

honestly im sure even the m10 could make more HP than the SR20 if you put enough work into it . For me its about playing to my skills, doing something fun and unique and saving some cash over what it would cost to get an m10 past 200hp . I have no background in tuning engine's like that , i dont have the cash or knowledge to start building that kind of power from scratch (I got much respect for you guys that have), but i do have a full machine shop at my disposal, i can make anything i might need, motor mounts, drivetain pieces, quite easily. So bolt in power just makes sense for me.

[NickVyse]

A standard non lsd 2002 diff can take way over 200hp and can live with 300hp. but like anything else it can wear out.

If you hear somebody has stripped a diff then ask the question 'why' I think you will find that there is no history or possibly it has done a few miles down the road, a properly built 2002 diff will take more power than a m20 tubo can push.

If you are putting a Nissan turbo in then why not fit the rear end from the same car if you are worried about it,

point well said. I seem to recall the m20 turbo that kept braking diffs was just chucking in any old knackered diff he had laying around as a stop gap for something in good condition. Let's hope he chimes in.

Good luck with the Nissan engine - should be a lot of fun. Out of curiosity do you know what it weighs? Be an interesting comparison with the iron block s14 and m10.