Heavy E body maximum HP for 8 3/4 rear axle

Posted By: PHJ426

Heavy E body maximum HP for 8 3/4 rear axle - 08/28/14 04:06 AM

In a big block E body for street and some high speed driving events what is the maximum HP you would toss at an 8 3/4 rear end.

This should be a lot more than an all out drag car leaving the line of a dragstrip treated with VHT and slicks on the car.

Currently there is a Dana in the car and shedding it for an 8 3/4 will save some weight but is the trade off in HP capability worth the extra weight in the rear of the car?

Attached picture 8253529-SCAN0035.JPG

Posted By: brads70

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/28/14 02:29 PM

I don't know the answer to your question but I went with DrDiff (strange S60) because it was lighter than an original Dana and I get everything new , upgraded taper roller bearings, truetrac etc...
Sold the 8 3/4 before I owned 2 of them....

Posted By: jcc

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/28/14 03:14 PM

I don't think anybody posting here can exceed the power capability of a well built 8.75 in a road race environment, and if they did, they would be at the top of the list for bragging rights.

The original twin turbo Cuda in "projects" forum would be an exception. Big Sticky tires, upgrade/optimized suspension, some aero, and big motor for salt falt runs would IMO start to reach the limits. And a 8.75 vs most others saves a few hp in friction losses and at that level might be important.

Posted By: Viol8r

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/28/14 03:25 PM

Quote:

I don't think anybody posting here can exceed the power capability of a well built 8.75 in a road race environment, and if they did, they would be at the top of the list for bragging rights.

The original twin turbo Cuda in "projects" forum would be an exception. Big Sticky tires, upgrade/optimized suspension, some aero, and big motor for salt falt runs would IMO start to reach the limits. And a 8.75 vs most others saves a few hp in friction losses and at that level might be important.

I am at 550hp+ with plenty of road course and autocross time. Stock everything, taper bearings. No issues in 5 years of hard running.

Posted By: TC@HP2

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/28/14 06:30 PM

My drag car was 400+ hp, launching at 4200 rpm with slicks, 4:30 spool rear in an 8.75 rear. No issues in the decade I ran it.

For a higher powered engine on a road course, it should be no big deal as the shock loading of dumping a clutch is whats hard on them.

Way back when, dragster were pushing 800+ horsepower through them and the Olds equivilent. Of course they were cut down to be no wider than a few feet, and they smoked the tires the entire quarter mile.

IMO, the 8.75 Banjo rear is pretty stout for most applications. Even the maligned 741 units have a larger pinion shaft than a number of other brands rear ends.

Posted By: PHJ426

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/28/14 07:11 PM

The current engine I have currently built for the Challenger is 512 RB stroker 4.25" crank 13.5 cr B1BS cylinder heads mechanical cam from my friend Scott Brown. Engine was built by the late Kenny Stafford funny car driver. I still remember when he called me with the dyno results from breaking the engine in. It made 700 flywheel hp.

Granted I have become bored with drag racing. I enjoy driving the cars and not waiting around all day.

Ill probably pull some compression out of the engine and knock a little power out of it. Might get it down to 650?

Posted By: PHJ426

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/29/14 02:44 AM

Talked with Scott Brown today about pulling the CR down to pump gas levels around 10.75....he says with the correct combination of parts this engine will be still around 700HP.....guess I will keep the Dana rear end in the car.

Next thing I need to figure out is if I will keep that 727 or go with a T56 so I can then calculate what rear axle ratio to run in this heavy barge....

Posted By: TC@HP2

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/29/14 07:47 PM

Don't overlook the possibility of using methanol injection. Snow Performance makes a nice unit that can use windshield washer fluid.

Posted By: PHJ426

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/29/14 08:16 PM

I was also hashing over the idea of running E85 since there is so much of it here in Illinois. It appears problems arise if the car sits for long periods of time.

I am going to get Scott the build number for the pistons and we will see if there is enough to give the pistons a haircut to drop the compression down a few points.

The head gaskets are Cometic and a thicker gasket can be used but its $$$$.

Who knows maybe a 200TW tire will hold the power coming out of a corner? If not there are stickier tires out there to allow for more throttle.

Posted By: brads70

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/30/14 04:27 AM

Quote:

Who knows maybe a 200TW tire will hold the power coming out of a corner? If not there are stickier tires out there to allow for more throttle.

Don't count on that. I have a somewhat healthy 451"(550ish HP) and 615k's and I can still steer with the throttle if I want.

I've run water injection before, works great. In the winter I added in isopropyl alcohol to keep it from freezing. There was no doubt when the water tank was empty.

Posted By: PHJ426

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/30/14 04:43 AM

I prefer not to rely on alcohol and water injection to keep the engine from pinging and knocking.

It's going to be a blast that is for certain.

Posted By: TC@HP2

Re: Heavy E body maximum HP for 8 3/4 rear axle - 08/31/14 12:34 AM

Quote:

I was also hashing over the idea of running E85 since there is so much of it here in Illinois. It appears problems arise if the car sits for long periods of time.

I thought about the E85 route, but...if I drive much outside of my immediate geographic area, I run the risk of not being able to find it or getting diluted mixes down around E75. Its much easier to find washer fluid anywhere you drive than it is to nail down good E85, so I went injection instead. Then again my engine was all together and swapping out pistons was not a consideration I would make.