How much HP & Nm through Berg 5-speed trans and SSC late model case?

[TexasTom]

If he's making the power & torque he claims, it'll push it ...

[-Alex-]

But the R&P makes it almost as same as beetle box with 3,88 R&P and 3,78 first gear. Engine doesnt make that power yet, its not assembled yet, only parts have been collected. What do you mean, it will push it? Can't 915 handle that power?

[Bruce]

This topic is about a Berg 5 in a late SSC case.

Not about 915 transmissions.

[team97]

This topic is about a Berg 5 in a late SSC case.

Not about 915 transmissions.

Like I said before, you drag race it you WILL BREAK it! Ask ANY qualified transaxle builder, type 1 cases are not strong enough for a lot of HP with slicks on a tacky track. Gussets, girdles, whatever....the case is not strong enough period. Better yet, ask ANY FAST drag racer, and I'm sure he will show you a stack of broken type 1 cases and R/P's

[Zach Gomulka]

This topic is about a Berg 5 in a late SSC case.

Not about 915 transmissions.

It's his thread...

But the R&P makes it almost as same as beetle box with 3,88 R&P and 3,78 first gear. Engine doesnt make that power yet, its not assembled yet, only parts have been collected. What do you mean, it will push it? Can't 915 handle that power?

It's a ways off from a 3.875 & 3.78- which is already tall. You would need to change out the 3.18 for a 3.64 with the 4.43 r&p to match the 3.88/3.78... And then that would of course mess with the rest of the gear ratios, you'd have to change them as well.

He means that you should be making enough power to overcome the tall first gear.

[-Alex-]

Yeah, it is my thread, so stop whining    And its not exactly about what R&P or 1th gear what is there inside, more means the  final ratio. 1st 3.18 gear  +  4.43 R&P is very close to 1st 3.78 + 3.88 R&P, where did you get the 3,64 first gear to match? I calculated the speeds with Glenn Rings calculator and with this calculator:

http://www.et-studios.com/motorsports/gears/gears.html

Calculate again and you see that early 915 box has very similar ratios as this planned berg-5, here are also speeds at  mph@4000rpm


Berg-5


R&P: 3,88

1st 3,78    20

2nd 2,06   39

3rd 1,48    52

4th 1,08   72

5th 0,82   95





Porsche 915/43


R&P: 4,43

1st 3,18    21

2nd 1,83   37

3rd 1,26   54

4th 0,96  71

5th 0,72  94



I have seen broken type 1 cases and R&P, thats not new to me    

[Zach Gomulka]

3.875 x 3.78 = 14.6475

4.43 x 3.18 = 14.0874

4.43 x 3.31 = 14.6475

I made a slip on my math earlier. You'd need a 3.31 first with the 4.43 r&p to match the 3.875 x 3.78

[-Alex-]

Yeah, but it is pretty close overall.  Just too bad that 915 is not the fastest shifting transaxle, or as good as T1.

<a href="http://www.youtube.com/v/UHQ7oMOEj6M" target="_blank">http://www.youtube.com/v/UHQ7oMOEj6M</a>

[Bruce]

Like I said before, you drag race it you WILL BREAK it! Ask ANY qualified transaxle builder, type 1 cases are not strong enough for a lot of HP with slicks on a tacky track. Gussets, girdles, whatever....the case is not strong enough period. Better yet, ask ANY FAST drag racer, and I'm sure he will show you a stack of broken type 1 cases and R/P's

Since this topic is in the street car section, your drag racing experience doesn't apply.

Besides, the pic posted above of the busted case shows it took 450hp to break it.  If you've got less hp than that........

[-Alex-]

Wonder how well would survive todays OEM transmissions with amount the torque that they are rated for by using SLICKS?     

[-Alex-]

I chose and bought Berg-5 speed kit for bus box, Rancho is going to build me it.

I want quick acceleration through gears, but there is no point to make supershort 1-4 gears and then long 5 gear.

There isnt so much gears to choose for berg 5, so these three ratios i have been thinking:


Choice 1

R+P 4.13

1. 3.11= 28.28 km/h

2. 1.93 = 45.57 km/h

3. 1.3 = 67.66 km/h

4. 0.93 = 94.58 km/h

5. 0.77 = 114.23 km/h



Choice 2

R+P 4.13

1. 3.11 = 28.28 km/h

2. 1.93 = 45.57 km/h

3. 1.35 = 65.15 km/h

4. 1.04 = 84.57 km/h

5. 0.77 = 114.23 km/h



Choice 3

R+P 4.13

1. 2.90 = 30.33 km/h

2. 1.86 = 47.29 km/

3. 1.26 = 69.81 km/

4. 0.93 = 94.58 km/h

5. 0.77 = 114.23 km/h

[Tomi]

With those ratios there will be no drag racing, just tire spin or bogging with your 300 hp. I wouldn't call that quick acceleration. Even with 4.57 final ratio the 3.11 1st is really tall, so why 4.13? For circuit racing I suppose you need even closer gears and probably much shorter 5th to get there. With so much effort thrown into your car, please do not make it a compromise.

[-Alex-]

Rancho recommended these ratios for my usage, which is mostly compromise between street and track and high topspeed. For dragracing these ratios are too long, i know.

But with 3.11 1st gear and 4.57 rp, its quite close to 3.78 1st gear  and 3.88 combination.  I have chosen now 3.11-1.86 mainshaft but the rest of the gears are not yet decided, they will be no superlow, but lower than stock 1303s 3-4 gear ratios and evenly spaced including 5th gear.


I could put 3-4-5 gears tightly together, like 1.48 - 1.14 - 0.89   but then would autobahn performance hurt. Or possibly leaving 5th as a long overdrive like Glenn Ring (3.88rp 3.78-2.06-1.58-1.21-0.82).