Some of you guys helped me out with some tough questions. Just wanted to give you an update.

Over the weekend we dialed the 540 in. Its a conservative tune, timing is not aggressive and the fuel is on the fat side. With 15 psi of intercooled boost we made 910 rwhp corrected to sea level through the mufflers at 6600 rpm. The torque reading was 880 ft lbs.

I did get to make it to the track and make one full throttle pass. The car ran out of gear way to early and managed a 9.36 at 141 mph. Nothing like bouncing the rev limiter for what seemed an enternity. At the 1/8 mile I was right at 120 mph, gained only 21 mph from then on to the end, not good. I need to get a license and have the chasis certified. The track elevation was 1200 feet and ambient air was over 100* at Speedworld in Phoenix AZ. Once the bugs are ironed out, proper gearing, better weather, and more seat time I should get into the high 8's. I can always step the tune up with race fuel and get more power if I fall short.

The car weighs in at 3,750 lbs, and is a street car that can cruise most anywhere as long as the tank is full of fuel.

One Tech question... I will be going over to 3.50 gears and I noticed that Richmond rates there street gears to 750 hp. The pro gear they offer starts at 4.10's on up, and its a softer gear usually only good for 30 passes or so. These pro gears have a high nickel content. This allows the gear to take the shock of drag racing.

Does anyone make a rear end gear that can handle this power and still be street driven?

I have Richmond 3.70's right now and they are hanging in there, just not sure how long they will though. May just get there 3.50 gears and see what happens. They both have 10 teeth on the pinon from what I read in Jegs, the 3.70's have 37 teeth on the gear and the 3.50's have 35 teeth.

Any help would be appreciated.

Chad

 

sorry i cant help with the gear thing, but congrats on gettin her running........8s should be no prob.

 

If you have 8 second potential, IMO you are going to need the 9310 "soft" gears sooner or later...probably sooner.

9310 is a high nickel content "impact" steel when carburized (or case hardened) and tempered so that the case is not as hard and wear resistant as street gears. The core of the tooth is very tough. IOW, the teeth will flex a little more under load without breaking off. The penalty is the short life of the surface of the teeth.

Because it's a 9 inch, how about having one pumpkin or drop out setup with street gears for cruising, and another with 9310s for the strip?

 

care to post some specs of the engine, cam, heads, etc.? Sounds like an awesome ride

What size tires are you running? Can you fit a taller diameter in the back?

 

Cam specs

668 intake
672 exhaust
@50 260 Intake, 270 exhaust 114* centerline Comp Cams

Cylinder heads Brodix BB2+ M2 Race System Heads 355 cfm

Dart Big M block
Callies Pro Mag 4.25" Crank
Oliver Billet Rods 6.385"
JE -20 CC 8:5:1 pistons

Tires used are Hoosier Slicks 29 tall by 12 wide, 12 inch contact patch.

If I go to a taller tire the circumfrence kills me. Hits the front of the fenderwell. I could tub the car and make it right but thats serious cash compared to a gear set. Car actually hooks up rather well, I am looking forward to launching at 4000 of the trans brake. This should get the car into the 1.30's in the 60 foot.

Chad

 

Nice!

 

Yep, the soft gears usually bend the teeth instead of breaking them off so at least you can finish a run.

I like the pumpkin swap idea OS proposed. Quick and easy swap.

-Mindgame

 

At your power level you will need to run a pro gear set..Keep an eye on backlash by setting a dail indicator against the case and working the pinion back and forth..Set the gear tight and replace them when they get towrds the max allowed tolerance..With a T brake and traction pro gears are almost mandatory..Id reccomend an alloy case..It will flex and absorb a little more shock than an iron unit and weighs less to boot..One time of unsprung weight is almost 3 times its amount in sprung weight.When your at the track dont forget to gently roll out of your burnout..Being that its a single digit car you have the luxury of crossing the line at any NHRA track so i suggest that you do that when you can..It will save the converter as well..When you line up and stage dont jerk the car by hitting the brakes, ease into the final beam and then hit the brake..Stabbing the brakes may cuase a very tiny amount of extra backlash in the drivetrain..Hitting the gears harder than need be but not helping out the car to get out of the hole better.

Whos axles and spline count do you have, alloy or steel spool?

Regular street gears will be okay while driving around but dont build up a boneyard caseing..A nodular iron unit with the gears set between midway and tight will help them hold up..Moroso max climbing lube is the way to go on the street case..Id run a synthetic gear lube on the race set..

 

I run a Currie rear end with 35 spline axles. They claim the setup I have is good up to 1300 hp. The center section is a Strange unit. I use a Detroit locker so I can drive this set up on the street.

Going from a 3.50 to a 3.70 gear how much difference will that be in mph? I am currently shifting at 6600 rpm, using a 29 tall slick. The 3.70's should have done 156 if I remember right? I really wonder if this even will be enough gear?

Talk to you all later,

Chad

 

this makes me real curious what rear end/gears monty uses on his 427tt vette, its the one thing on his great website that is not mentioned

 

If your tire is really 29 inches tall at 140+ mph, and you went 141 @ 6600 in 3rd gear of a THM400 with 3.70s, your TC was slipping about 600 rpm. Zero slip would be about 154.

Here's some good calculators.

http://murray.faithweb.com/formulas.htm

At any given rpm, speed is an inverse function of overall gear ratio. (or use the calculator)

3.70/3.50 x 141 = 149
3.70/3.30 x 141 = 158
3.70/3.00 x 141 = 174

 

monty's car is a street car.. no traction, so the gears don't really matter.

 

Gotta love it when you're out of gears just past the 1/8 mile mark. You got a bunch left in it, in my opinion. I was running only about 5 MPH slower than you through the traps in a car that ran a full second slower ET.

The "taller" gears will also probably help your rear end live under that strain bit longer, too. And depending on how much traction you've got it might launch just as quick or quicker. I found that my rear end "tuning" was quite different depending on how steep the rear gear was. Mine liked a softer "hit" to the tires with the milder gear which was just the opposite of what people told me to expect at the time. Go figure.