3DFORMULA

I'm putting together an automatic trans bracket car for the local 1/8 track. I would like to hear from some of the experienced fellas what they would think of a powerglide behind an LT1 for the 1/8. What would be needed torque number wise and gearing(tranny and diff.) wise for this to be a worthy combo.

I have:
CM 233/239, 569/577 lift cam 108 intake centerline 112 lobe sep.
GTP stage 1 heads with 2.00/1.56
Dry nitrious kit-gonna switch to a NX wet kit however 100shot/200shot if needed
12bolt 4.56
28" slicks

These parts can be handed down to the 'bird if needed replaced.

Tell me:
1. Torque convertor

2. Compression, pump gas preferred, or is it gonna need 12.5/higher to get the power needed

3. Rear diff. gearing and tranny gearing

4. 26" slicks?

What do I have to do for the 'glide to work for me.

kazman

What type of bracket racing are you doing? 400 or 500 Pro tree, sportsmast tree, heads up, index racing, or plain bracket racing. What's best doesn't mean the fastest. Bracket racing you just put a dial-in on the car and do it. I converted from a M6 to a turbo400. I should of put in a glide. The glide will launch softer and are more consistant due to only 1 shift. When not properly warmed up my turbo 400 is as much as a .10 slower. For brackets I would nix the spray and go motor only. Glide with 28" slicks and 4.56 gears sound right to me. With that setup you could go stock or use the upgraded heads and cam. The "best" setup for bracket racing is one that allows the car to hook on spit and still allows the car to launch hard enough for you to cut a good light.

3DFORMULA

Plain bracket racing. I believe .500 sportsman tree. More info: My '94 Z/28, a/c, p/s delete, many common weight reductions with continued indepth weight reductions. Race car only. 6.7-7.0 desired time range, however consistency is priority #1.
I just adjusted the nx shot, however I could just build the motor a little stronger to get the desired #'s. I still ? the power level and whole package needed to get there with an LT1/'glide combo.

Stephen 87 IROC

Torque converter required is based on the engine's powerband. What's the advertised duration of the camshaft. Is this for street/strip or strip only?

Before looking for a PG, pick up this book. It will tell you everything there is know and how to modify a PG transmission. Over the years there were lots of different versions of the PG. The 1.76 first gear V8 versions in the later years are the most popular but parts can be mixed and matched from different models to build a good PG.

http://www.amazon.com/Powerglide-Tra.../dp/1557883556

The first thing you should do is upgrade the input shaft to a turbo spline shaft. That way you can use a TH350/400 torque converter instead of a course spline PG converter.

There isn't a whole lot that needs to be done to improve the PG. New input shaft. Steel center clutch hub to replace the factory cast one. Dual seal piston servo. Kevlar band. Everything else is bells and whistles to make it even better.

Although they're not hard to work on, finding a good core is getting difficult. There are lots of better aftermarket versions available to suit all racing demands. You don't need a transmission capable of withstanding 2000hp in a bracket car.

I run a basic glide behind my 540 and it's pushing me into the low 9's.

3DFORMULA

Thanks for the book info Stephen 87 iroc. Advertised @ .050 is 233/239, racer only

jakesz28

I'm running a glide here. My car feels like it is leaving soft and doesn't pull the front very high. But I have been 60' low 1.3's. I've been leaving on a .075 nitrous jet and it is very controlled. I've seen other cars have problems leaving on less power and with slower sixty foot times. A few of them were standing their cars up but no problems here. I was trying to get in the 8's but pushed the the band adjusting bolt out of the caes while trying to leave on approx 275hp jet.


I would look for a 1.76 low gear and run a turbo spline. Your going to need a good stall to get you out of the hole if you decide not to spray the car.

AutoRoc

It'll work fine but your gear/converter/tire will depend on power/weight/powerband peaks, both TQ and HP. Guess one, you might as well guess the rest. 200hp worth of hose will need a different converter to work good vs. no hose. There's not a lot of middle ground like a 3 speed trans for both Nitrous/NA use. If you do a 4000 stall, it might be perfect on hose but N/A it will be .5 slower than a dedicated N/A converter running N/A.

1. custom converter...spill the details and nitrous use to the builder.
2. 11.5:1 is good with pump gas. Run VP113 for added power if you want another 25hp.
3. Have a 1.76 glide built with a protree T-brake, good input shaft..should be $900-1300.
4. Keep the gear/tire you have. A 26" tire will be needed only if you go thru the traps UNDER your shift point. Which I think you will. The long first gear needs ALL of the reargear it can get for acceleration. A bandaid is a smaller tire. it's a bandaid because the smaller tire will be less consistant in the traction department. Always put the tallest tire avaliable and gear the rearend accordingly. Goodluck!

Stephen 87 IROC

Advertised duration is the total, not the @ .050" duration. With the advertised duration, I can recommend a stall speed.

3DFORMULA

Here are the cam specs:

Part # 07-000-8
Engine LT1/LT4
Grind # LT1 3442/3442 HR112+1
Serial # A 3262
Gross valve lift .569/.577
Duration at .006 283/289
Valve timing at .050:
INT OPEN 8 BTDC CLOSE 44 ABDC
EXH OPEN 55 BBDC CLOSE 3 ATDC

These specs are for cam installed at 108 intake centerline:

Duration at .050 233/239
Lobe lift .3560/.3610
Lobe Seperation 112.0

Ken95Z28

I'm running a glide 1.76 first gear 4.10's on 29' tires.
Running an ATI Converter with there transmission. This will be my third season on this transmission and so far it has not let me down at all.

1.5's to low 1.6's in the heat of the summer here in Oklahoma.

AutoRoc

Hi Ken, any info on your shift point and also the rpm which you cross the line? What gear do you think 3D Formula should run for 1/8th mile?

Stephen 87 IROC

That camshaft is going to want a converter that stalls around 3500 when using nitrous. 4000 if NA.

Gearing and tire size will need to match the rpm range of the engine.

Don't expect a deep enough gear to use the full range of the gears in the transmission. If the diff gear is too deep, you'll have too much torque off the line and overpower the tires. Depending on the tire size, 4.10 - 4.86 is a good choice although I've seen some small tire cars go as deep as 5.13.

With 4.86 gears, 6000 stall and a 32" tall tire, I was shifting from low to high around the 330' mark then pulling all the way to the 1/4 mile in high gear. For consistency, you want to get out of low gear as quick as possible. It won't make the fastest run but fast doesn't win in bracket racing.

mdacton

I would not put a PG behind that....

your going to end up with a dead horse. get a 350.

jakesz28

I think it all comes down what your main intentions are. If you want to run on the motor it will require a differnent convertor. If your main thoughts are motor passes you will be able to run a lower first gear and not over power the tires as easily. But on the other hand if you want to come off the line on a 200 shot. The higher first gear in a glide will be easier to hook and more consistant. The problem of leaving under a lot of torque(power) is one time it might hook, another time you blow the tires away, and the third time it goes on the bumper and hurts alot of stuff on the landing.

One mans combo may not be right for another. But convertor technology has gone a long ways. I would talk to some good convertor companies about what your real intention s are.

My combo on motor is slow. I could easily put the car in the nines on the motor by changing convertor and gears. But I'm thinking of something else.

Ken95Z28

I shift around 6900, RPM currently on my 29's is about 6450. It really needs some 4.30's in it right now. A lot of people told me that it would be slower but it was not, it was quicker. If you miss the setup by choosing the wrong converter then I could see that. Get a good one, I talked to the ATI folks and they setup me up with a good one.

I can't wait see how my new setup is going to be this year, going to a Methonal Injection System. It should hit a little harder at the line this year, it should put me back in the low 1.5's to 1.4's.