| NSR21L |
Posted
Thursday, Jun 5th 5:38am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 75
Sydney NSW
BMW E21 323i |
Hi Guys, this question has probably been thrown up a few times in the past.
would anyone know how much power an open 3.45:1 diff take before it gives up?
will greatly appreciate your feedback
thanks |
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| JDBeyer |
Posted
Thursday, Jun 12th 5:03pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 235
N. Humboldt county Ca.
82 323i on steroids |
I have sure hammered mine with the stock engine.
But I have been running a 3.91 LSD with the stroker and am putting 197H.P. to the wheels, Has not blown up, but there is no spinning wheels till the clutch is engaged anymore.
I have found that these diffs. will last a little better with LSD in that the side gears are a weak point and with LSD they don't spin so wildly and come apart, then go though the ring and pinion.
Jeff |
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| MayanArch |
Posted
Saturday, Jun 14th 2:07am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 1573
Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978 |
| JDBeyer wrote: | I have sure hammered mine with the stock engine.
But I have been running a 3.91 LSD with the stroker and am putting 197H.P. to the wheels, Has not blown up, but there is no spinning wheels till the clutch is engaged anymore.
I have found that these diffs. will last a little better with LSD in that the side gears are a weak point and with LSD they don't spin so wildly and come apart, then go though the ring and pinion.
Jeff |
JD,
How did you determine this? Did you dyno your car? What is in it. I am dying to find out what I am pushing.
What goodies did you do to your engine, aside from the 2.7L stroker?
have you measured 0-60 times yet? I have a 3.91 with my stroker as well, and would love to get accurate times on 0-60 and other times. |
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| JDBeyer |
Posted
Saturday, Jun 14th 5:22pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 236
N. Humboldt county Ca.
82 323i on steroids |
Veiw my car,it is all there except:
Extrude honed intake, High presure water/alcohol injection. different brakes and wheels.
And I did run it on a chassis dyno.
To get those H.P. readings with kjet injection I was running way to rich, so megasquirt will be going on this car next.
Jeff |
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| MayanArch |
Posted
Saturday, Jun 14th 9:22pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 1577
Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978 |
But I have heard that the 2.7 gets you up to 195 or 200 hp. How can a 3.0 get you to the same place?
Did you free up the exhaust side at all, or just the intake?
A stock 325i was 189 hp according to BMW. You should be able to achieve more than that with a free flowing system (input and output) , megasquirt, and a 3.0 block. |
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| melloh |
Posted
Saturday, Jun 14th 10:32pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 672
California, USA (San Jose)
1980 320is, 1991 318is |
I think much of the discrepancy may be HP output at the wheels vs crank. His readings are 197 at the wheel, meaning something like 226-236 crank (assuming 15-20% drivetrain loss). Also, we don't know his torque numbers, either... I'll bet he has some good gains over stock there as well. |
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| MayanArch |
Posted
Saturday, Jun 14th 11:42pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 1579
Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978 |
wow....that much. What is this due to? flex of the tires and drive shaft? |
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| melloh |
Posted
Sunday, Jun 15th 11:03pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 673
California, USA (San Jose)
1980 320is, 1991 318is |
Good question! Wish I could answer that 
I just know it happens, but that estimate I gave is pretty hypothetical b/c the % loss is different for every car.
I did find this website but I haven't read through it. Even if I did, I wouldn't be qualified to verify its efficacy, validity, or reliability.
http://www.superstang.com/horsepower.htm |
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| NSR21L |
Posted
Monday, Jun 16th 3:06am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 76
Sydney NSW
BMW E21 323i |
Reason why i ask this, is I'm performing an engine transplant and shoe horning a LS400 v8. With the current ratio 3.45:1, i really don't want to change anything on the final drive. |
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| NSR21L |
Posted
Monday, Jun 16th 3:09am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 77
Sydney NSW
BMW E21 323i |
I forgot to mention i only have at the moment the 3.45:1 open diff not the LSD |
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| TJ |
Posted
Monday, Jun 16th 6:22am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 62
NY, USA
82 528e2i 84 320i/4 80 320i |
if you're putting in a V8 maybe should try converting to an e12 diff like I saw here http://www.bmwe21.net/forum/viewtopic.php?t=4788
BTW, the e36 325i (24 valve M50 engine) is rated 189hp. The e30 325i is 168-171hp stock. So 195hp at the crank even would be pretty good for a 2.7 M20. |
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| NSR21L |
Posted
Monday, Jun 16th 2:16pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 78
Sydney NSW
BMW E21 323i |
would any one know the different diff ratio that were fitted to the 5ser models just to get a fair idea. i thinking any ratio near 3.45 or lower would be ideal for me. |
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| MayanArch |
Posted
Monday, Jun 16th 3:05pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 1580
Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978 |
The BMW 3-Series book by Jeremy Walton lists:
E21 323i - 143bhp @ 6,000 rpm
E30 325i - 171bhp @ 5,800 rpm
Alpina C2 2.7 - 210 hp @ 5,800rpm
The C2 was naturally aspirated, right?
I also remember Ray posting an article on strokers that said you could get to 200 hp by doing the 2.7 conversion.....but I cant find that article now.
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| MayanArch |
Posted
Monday, Jun 16th 3:28pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 1581
Florida, USA
Baur E21 2.7 1982, Baur E30 318i 1985, 323i 1978 |
2,623lbs to 198hp is 13.24 pph |
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| TJ |
Posted
Tuesday, Jun 17th 1:54am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 63
NY, USA
82 528e2i 84 320i/4 80 320i |
looks like any e12 528i should have a 3.45:1, 525s have a 3.64:1, and an M535i or other model with the optional close-ratio tranny would have 3.07:1
I think the 2.7 strokers that are just a mix-and-match of stock BMW parts probably won't see 200hp, but it's definitely possible with aftermarket or custom performance parts. I would consider anything with a higher hp/liter and torque/liter compared to a stock 2.5 to be a pretty good setup. |
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| NSR21L |
Posted
Tuesday, Jun 24th 10:44am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 79
Sydney NSW
BMW E21 323i |
I'll start modifying the rear subframe to fit a e12 diff and let you all know how it goes with some pics thanks guys for all your help |
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| ArnZ |
Posted
Tuesday, Jul 1st 9:50am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 135
Qld, Australia
BMW 323i |
i snaped the spider gear housing with my stock 323i with 3.45 ratio diff.
so yeh your better off getting something stronger |
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