Oh no I think I have a 3.09 4-speed, help!!
Hang on they only give me 420 characters in the profile page, so I'll have to rearrange stuff and put it here.
I am assuming this is a direct 4th no overdrive trans.
Here are the ratios and splits;
3.09-1.92-1.40-1.00 splits of . 62-.73-.71
2.66-1.91-1.39-1.00 splits of .72-.73-.71
So the splits tell you that at whatever rpm you outshift, the inshift will be at those percents. So in your case outshifting 1st at 6500,it will drop in at .62 x 6500=4030 vs 4680 with the 2.66 low. This should load up the turbo nicely. All other splits are the same.
So I don't see a downside here.
But getting back to your question in my profile page;
Your question was;
Hi AJ, I hope you can help me understand what I'm dealing with.
I've got a Hemi 265 straight 6 from Australia, EFI setup, turbo, about 500hp. The cam is very streetable. Rear will be 3.54
NOW...I got a 4 speed box from the USA but it looks like a 3.09 input and cluster.
The car will be a tough daily drive
any ideas?
That's a tuff one for me,never having had a turbo anything. I can tell you tho that 3.09 x 3.54 =a 10.94 starter gear, which is a very nice starter gear for a NA 367 cuber with about 400 hp....like mine. I could go with a little less starter gear, but since I have an overdrive, I just leave it. Besides I like the 1-2 split which is 1.92/3.09= 62%. That split lets me blast out of the gate, and then get down to business, in second gear. If you are making 500 with that little 265, I'm betting it's gonna be spinning some to make it, or running a lottof boost, or some combination of that. The point being that a big turbo to make 500 with a little engine, is usually a little soft on take off. Now the very streetable cam, kindof tells me its a small duration, perhaps 265 to 275 advertised,unless it's a roller than it could be 10 or 15 degrees bigger. That will steal a little torque off the bottom as well. So I don't see a 3.09 low as a problem.
Look at it this way, you can always short shift it and let the boost take over. Then when not getting on it, you can depend on the starter gear to get you moving.
Another way to look at it is the 3.09 is only 3.09/2.66= plus 16% TM. So you can launch at 16% less torque. This might be a couple of hundred rpm lower.
Or if the chassis can take it, you can launch with that extra 16% TM, and be quicker.
I don't see a downside to the 3.09 low gear. I knew as soon as I put it in , that it was exactly right for my 3.55s. The rest of the ratios are very nearly the same as the ratios in the 2.66low box.
And the low gear itself is the very same gear as what's in the 2.66. They just changed the cluster drive ratio up front, and re-engineered the other ratios to match.
For a tough DD I think you will like it; probably a lot.
Getting back to post #14, whoever told you the Rs would drop so far, needs a lesson in math. To drop from 6500 to 2100 is a split of 2100/6500=.32 or to 32 %. That would make 1st a Granny gear, something like a grain truck would have or a cement truck,lol! I have never heard of a P-car trans having a split that deep.
In the Mopar line-up, one of the biggest splits can be found in the OD box.The ratios are 3.09-1.67-1.00-.71, and the splits are; .54-.60-.71.. Even in this box the Rs would only drop from 6500 to .54 x 6500= 3510
Hope I've been helpful
BTW; those cam specs; are those numbers at .050?
