Hey guys, I'm going with a 9" ford for brute strength, however I do know they aren't the most efficient rear ends available. What kind of power loss (parasitic) can I expect going from a 10 bolt with 4.10's to a 9" with 4.10's? Thanks guys!

 

11.60's to 11.90's....an example from my buddy with a 3G. 11.60's on the 10bolt, and 11.90's on the 9".

chris

 

I stayed about the same because you can inflict harder launches and shifts on the 9".

Went from 10 bolt 4.10 to 9" 4.11 !!!

 

OUCH!!!! I could potentially lose 3 tenths because of the rear?!

 

The numbers I've seen published in a tech article in National Dragster indicated the losses were:

Dana 60 - 5%
GM 12-bolt - 7%
Ford 9-inch - 10%

I would assume the 10-bolt is close to the 12-bolt, since the relationship of the pinion shaft centerline to the axle centerline is similar. So, you could expect to see a 3% drop in rwHP. In a 500HP setup, that would cost you 15HP, which is about 0.10-second and 1.1 MPH.

 

You COULD ,,,but as I stated I didn't !!!!!

 

i did a swap in a 99 hugger and he picked up et, we went from a 10 bolt 4.10 and put a 9" 4.30, car actually hooked up better and 60' ed like a ****...
hi mike.....

 

lol hi scott! I'll call you later today, thanks for all your help with this. I babied the car back to my apartment, I'm sure I can at least drive it on to a trailer, I hope....

 

yeah that was just and example...he also swapped to a TH-350 around that time so we were still trying to figure out what killed us more. Only reason we think it was the rear is we lost weight on the trans swap but gained significantly on the rear. Car still hooks like a son of a gun. Just things to figure out.

Chris

 

yup, going from a 700r-4 to a t350 will definetly drop et, the 1st in the 700r-4 is 3.06 and the t350 is 2.48 big difference in torque multiplication.

 

yeah so that's probably where his et trouble came from, but I don't think he was thinking it would hurt him that much. He dropped half a second and it suprised the snot out of all of us...everyone was looking for other issues, then he decided to tell us the car runs really fat on the top end, and TPIS can't even lean it out right for him...loads of fun.

Chris

 

Hey MIke, i finished your 9" center and i got some pics, but i can not post here so hit MM and i'll post them up.

 

dam mike i can not get the file small enough to fit ,MM wont accept it , any ideas?

 

email them to me! Mike94ZLT1@yahoo.com. I'm gonna order the BMR stuff right now. Thanks scott!

 

On a 400rwhp car people are usually seeing 8-12hp loss from a 12 bolt and 15-20 from a 9 inch at the wheels.