.............. I am also thinking of running a 9 inch in the bird as opposed to the quick change in the roadster if I think I can get the gear ratio were I want it.................
If it was me and you wanted to try and run in the 240-250 range I would get rid of the quick change unless you had one with a real high (low number) ring and pinion.
Let's say you had a circle track quick change that had a 4.11 ring and pinion. Right now at 206 mph the pinion is spinning at 10,169 rpm if you have 28 inch tires if I did my math right. Now take it to 240 and that pinon will be spinning at almost 12,000 rpm (11,848 rpm). If you ran a 2.47 Ford the pinion would be turning about 7100 rpm and so would your motor which seems to be a good rpm based on what you said you were turning in your post.
Sparky will try and get you into a GM 2.28, right sparky
, and the pinion speed would be great at 6600, but the engine speed will also be 6600 assuming a 1 to 1 high gear which might be low on your power band. Up at the 300+ he is running along with the gear vendors overdrive it is just the ticket and I think he might even be running a higher (lower number) GM than the 2.28.
For what it is worth we also make our best power in the 6900-7000 rpm range and ran the 243 in '06 with a 2.47 rear and 28 inch tires and a muncie. This year we ran the 250+ at about the same rpm, but with a g-force transmission using a .93 overdrive 4th that would have given us a little under 7500 rpm pinion speed with the same 2.47 gears.
There is a land speed quick change made with I think a 2.09 ring and pinion, but I believe it is close to $5000. We will look at one of those if Hooley builds a true comp coupe car to replace the stude.
I have a spreadsheet for the pinion speeds that I made, but it isn't on my site, but could be if there was interest in it.
Good luck,
Sum
