pologreen1

I know that every body says 3.75 is way too steep to take on road course, but now I have a very well ported sr set up and I will atleast port! if not do heads and cam swap. But what I want to know has anyone ever used these gears on a track, one guy told me he had sr with stick and 3.90 gears on road america. I will only be doing it like one or two times a year.
should I get a stall or is that more for drag?

AU N EGL

Andrew?


There is one other forum member who uses an auto C4 on Road America too. He should chime in

pologreen1

yeah but he has 3.07 and he already thought that they are too steep but I have them so I would have to make do! I was hoping some one has done hpde with these could say how bad they are for long haul!

Aardwolf

You may want to confirm this with your own ratio calc and trans expert, in D at 130 MPH on a 3.73 you would be turning 6300 RPM. I think that is really pushing the stock bottom end and you would quickly have a failure. With a rebuilt bottom end OK, but I think 130 MPH may get exceeded. Then 140 MPH would be 6800 RPM. This is in third gear, 1to1 ratio. If you want to go into OD and drop the RPM, your putting a lot of strain on the trans as the 3/4 is notorious for failing. So if you'd like to use those different gears your best bet would be to have a trans rebuild that can withstand high speed, high RPM, shifting to OD.

By way of comparison this season I was turning 5200 at 130 MPH in D. This is all the car had, with upgrades this winter it will go faster but I don't plan to use OD. The 3.07 gear will allow 150 MPH at 6000 RPM. So I really have room to grow HP wise.

3.73 at 140 MPH in OD would be only 4800 RPM. I use the 130 and 140 MPH speeds because that is likely what your car will do. Depending on weight you may only get to 120 MPH. I don't really know a lot about your car so can only guess.

What events are you planning to attend?