How much power through a 70's 4.43 ring and pinion?

[gliding_serpent]

I have run into a bit of a curve-ball with my rebuild. 1984 911 3.2 - The beginning of the end

In short, I have found out that my 915 3.2 has a 76 7:31 (4.43) close ratio ring and pinion. This is a good thing... so long as it can handle my planned ~260hp 3.4L, mid-range torque heavy, SSI setup.

I did some searching to try to get reliability opinions, but get my own post in the search, and a number of posts copy/pasting info From S. Zimmerman comparing ratios and weights of the 915 vs G50.

My ring and pinion is ok I believe (no pitting of the hardening, but some mild scoring). I am fully aware of the cost of a good ring and pinion from Guard, and the cost of the labor to install. Options in my head are as follows...

1. Keep what I have so long as others have experience with reliability with the power levels I will be putting down. Could be "false economy" in a new engine/tranny rebuild.

2. Go for a standard used 3.88 which should be a bit more reliable.

3. Go for the full monty Guard unit.

Thoughts and experiences appreciated. My education would suggest that options two or three would be best.

[CBRacerX]

I ran one for years with a 300HP race 3.0. No issues. You should be just find, keep good oil in the trans.

[gliding_serpent]

Reassuring to hear.

[Flieger]

The power rating is more limited by the heat that the gears see, so coolers and pumps and spray bars can give you more power capacity. The killer is torque, since that is based on the pure strength of the gear shape and material. Even with all the cooling in the world gears won't gain much in torque capacity, but you can spin them faster.

[gliding_serpent]

3.6L sc conversions killed second in two of our local cars. Thus i will spring for something from guard for second.

When the poster above said 300hp from a 3.0, i figured that he gets that from rpm more than torque, but that we might be in a similar ballpark.

Good point on cooling... Yet another thing the euro cars of our era had that we do not.

[Bill Verburg]

I'm curious as to what 915 you have. Most '76 would have come through w/ 8:31 but there were a few 7:31

Sooooo, what model is it? 915.??

[Trackrash]

A reinforced or HD side plate and one piece bearing retainer should help.

If you are drag racing all bets are off.

[CBRacerX]

Originally Posted by gliding_serpent

3.6L sc conversions killed second in two of our local cars. Thus i will spring for something from guard for second.

When the poster above said 300hp from a 3.0, i figured that he gets that from rpm more than torque, but that we might be in a similar ballpark.

Good point on cooling... Yet another thing the euro cars of our era had that we do not.

Correct this was a 6-8K powerband motor. I did not cool the 915 Aluminum trans but did change the swepco often