Torque of S50B30US vs S52???

[Overlord475]

I've searched for a while and there seems to be very little information on the net about the S50B30US.

Can't seem to find the torque numbers.

What's the torque rating of the S50US and those of the S52?

Also, what HP and Torque gains are to be expected from an OBD1 swapped S52?

[e30s50dan]

dude....ur goin'a get the "SEARCH" thingy

[Mr Two]

Torque doesn't matter, just look at the area under the horsepower curve when comparing things.

[nando]

Torque doesn't matter, just look at the area under the horsepower curve when comparing things.

it does matter, because the torque curve of the S52 is deeper and wider - where do you think that extra HP area comes from? :)

[99em1]

No brainer. S52.

[JGood]

20 pages of answers for you:

http://forums.bimmerforums.com/forum/showthread.php?t=454142

I'm sure there's a few s50's in there.

[Overlord475]

Torque doesn't matter, just look at the area under the horsepower curve when comparing things.

Torque is what matters.

Torque is your 0-60 time while HP is you top speed.

And Torque..... is what puts the smile on your face and the kick in the ass.


The reason I am asking is because I have the opportunity to buy either a rebuilt S50US or a rebuilt OBD1 S52. There is a decent price difference and I am trying to decide whither or not the deference in performance is worth the extra money.

They are both rated at 240HP stock with 225ftlb of torque for the S50 and ~236ftlb for the S52.

HP is the same because the heads are relatively identical. But the torque is increased slightly by the extra stroke of the S52 (89.6mm vs 86mm).

Torque comes from stroke and bore only.... and has nothing to do with the head.

But, when the S52 is swapped over to OBD1 the HP is increased due to the M50 Intake plenum.

If I'm thinking correctly the torque numbers of the S52 will not change once converted to OBD1, but the HP will increase due to better intake flow.

[Overlord475]

20 pages of answers for you:

http://forums.bimmerforums.com/forum/showthread.php?t=454142

I'm sure there's a few s50's in there.

Nice!

That thread is awesome.

There's a 1995 S50 on the first page

[nando]

Torque comes from stroke and bore only.... and has nothing to do with the head.

But, when the S52 is swapped over to OBD1 the HP is increased due to the M50 Intake plenum.

If I'm thinking correctly the torque numbers of the S52 will not change once converted to OBD1, but the HP will increase due to better intake flow.

That's not right either. Your torque curve is very closely related to the VE of the engine, which is developed in the head. Yes, increasing displacement will increase torque - but VE is basically your effective displacement. If you plotted them next to each other the torque and VE curves would be shaped nearly the same. The S52 has better overall VE and increased displacement, so the torque curve is wider as well as deeper.

You can't gain HP without increasing torque, other than simply spinning the motor faster (which doesn't really work either, as torque usually drops off past a certain point). An OBD1 conversion effectively increases the VE of the engine, which increases torque output, which in turn increases HP..

[Overlord475]

^ You're right, sorry... Wasn't thinking about volumetric efficiency.

What kind of HP and TQ numbers are we talking with a stock S52 that has been converted to OBD1?