TRex

iTrader: (3)

OK, looked through the old threads and I see that 9 inches cost about 20-30 hp on the chassis dyno. I'm wondering if anyone has any data on e.t./mph loss with the 9 inch ?

I've got a very mild 02 SS M6, 345 factory options, free mods, pulley, filter, synthetic fluids, on BFG DR's. Car is lowered for AX with AX suspension and brakes. I am thinking of upgrading the rear on it because I am scared to death of breaking the stocker. No clunking or whine yet, but I've read the breakage stories.

Looking at a 9 inch with 4:11's and a beefed up torque arm.

Anyone have any thoughts or data to offer ?

bigMAC

I would get a 12 bolt instead of a 9inch. It will cost you less power, its cheaper and it is plenty srong. You probablly wont need a 9 inch unless you are making like 700 horsepower.

2MuchRiceMakesMeSick

I have never seen the 9" lose that much hp. I have seen 15 hp at the WORST case. Im not sure where your getting 30 hp from. I think the differential makes a big difference in hp loss. With a spool you will loose the least.

ONGRNGO

I don't think your ET will drop at all you may gain, because you will be able to launch at 5500rpm, as long as you have stickies out back. But I will let ya know by spring, I have a 9" with detroit locker and 4.30 gears on the way

Dan

WAHUSKER

iTrader: (4)

Going from stock 3.42 gears to 4.10s should pick up 2-3/10ths (faster) and lose 10-15hp. At least that is what they did for my car, & I went from 3.23s to 4.10s. (-3/10ths & -14hp)

obe1 95Z28

If you plan on adding more HP later, the 4.11 gears will cause you to need to shift into 5th gear before the end of the quarter mile. Additionally, on the street 1st gear will be worthless as you'll just break the tires loose. You might want to review your gear selection (I found out the hard way).

2MuchRiceMakesMeSick

You hit 5th in the quarter with 4.11s? What was your trap speed? Im guessing you would have to hit at least 140+ in the quarter with a good set of drag tires

mcflyz28

I just raise my limiter to keep from shifting crossed at 118 MPH, that was a 5k clutch dump on slicks rear end is howling worse than the wife !!!!

ONGRNGO

Or you could just put on a taller tire too

Dan

TRex

iTrader: (3)

I plan to get up to about 400 rwhp max. I will raise rev limiter if need be. I plan to trap about 117-118, which would be 4th gear. I'm already in 4th stock, trapping about 109, so no big loss going to 4.10's, I'll just be at a little higher revs.

Thanks for the response WAHUSKER, I knew I would be quicker because of the 60 ft improvement, I should have asked how much mph I would lose with just the 9".

This was an old thread, I have already decided against the 9" and the 12 bolt because of weight and hp loss. I'm building an 8.8 hybrid this winter, launching off the limiter in the spring. YEEHAA

obe1 95Z28

I shift at 6,200 rpm with my Vortech S Trim blower, with my 26" tires that only gives me 115 mph trap speed. My best trap speed was 124.8 mph.

TRex

iTrader: (3)

Sounds about right obe1, 6300 would be 117, 6350 would be 118, right where I want to be. Thanks for the info ;-)

guadofreak

iTrader: (1)

I gained in the ET however lost a few mph with my 9" I am sure the gears(4.11's had something to do with it though)

badass 2002 z28

iTrader: (5)

I went to a TH400 and a 9inch and didn't really lose any MPH...well maybe 1mph if that

Bryan TTM

you dont need a 9"...and if you put one in you wouldnt see any loss...yes they are not as efficient...but i've seen plenty of 10 bolts takin slicks & 1000hp...nobody on this forum makes that kind of power...9" are nice...12 bolts are nice...believe it or not, your 10 bolt is tuff enuff...c-clip eliminator, brace/girdle, good posi unit, & dont weld the gears...it does help to weld the tubes to the housing tho...spend your money elsewhere, on something that will make a diff

matts22

iTrader: (2)

Are you saying that the 10 bolt is strong enough to handle any car on this board? Give me a break, there have been TONS of people break 10 bolts with a stock car, M6, and nittos (maybe even street tires). You seriously think they can handle 1000 hp with slicks? Please tell me you're joking.

If you drag race, have a 6 speed, and plan on any serious mods in the future (heads, cam, blower, nos, etc.) you will need an upgraded rear. No ifs, ands, or buts.

TRex

iTrader: (3)

Yeah, we've all seen lots of twisted axles. No good way to beef those up on a ten bolt.

2MuchRiceMakesMeSick

What are you talking about? I have seen 12 bolts break with 400 hp with m6 cars. If you did see someone dump the clutch with slicks with a 1000 hp and their 12 bolt didnt break, they were lucky. The 10 bolt is enought??? This is getting more and more rediculous.

ONGRNGO

There is no way that a 10bolt will hold up to a modded 6spd. My car with only 340RWHP and 350RWTQ broke the 10bolt on nittos And I have also herd that some 400RWHP M6s are breaking 12bolts and thats sad I think I would go the safe route get the 9" with the 4.11 or 4.30s with the locker

Dan

Orange Crush 408

iTrader: (-2)

420rwhp snapped the 10 bolt. Now I have a Moser 9" with 35 spline axles, 3.73's and a locker, this rear end is awsome. But with my 408 I can't get any traction.This is my only complaint. I still have not even used my 300 shot. Oh boy.