Disappointed in my gear ratio choice.

[Ziegelsteinfaust]

In my C10 I have a pretty close to 475hp 383 LT1 gen 1.5 or 2 depending on whom you ask backed by a TH700 with a 2500 rpm stall converter, and 30x9.5x15 tires.

I just had 4.88 gears, and a Detroit locker installed. To be honest I have been disappointed in my choice this weekend. Driving it around is fine. A little hard core, but not bad.

The problem is going for distance. I can start a burn out, but carrying it for distance my engine doesn't rpm hard enough.

I know my carb still needs tuning, but with the old 3.42's. It would carry the one tire fire for a easy 150 foot till my truck got out of shape. Now it is hard to get past 50 foot. Alot of that is due to the locker I know. As I have twice the traction to overcome.

Is this a normal issue where deeper gears do not burnout better due to greater need for rpm gain? Where my 383 could push the burn out with a decent amount of torque. It can not rpm hard enough to carry anymore.

I am trying to figure out where I went wrong or where I need to go right to bring my combo back togather. I have gone fairly extreme on the choices with a smogger spec motor as it is what I had. It is a damn fine motor, and I don't want to detract from it's builder. I am trying to come up with a concept of where I need to look. To bring everything back in line.

What makes a engine rpm hard throughout its rev range?
Let's stick with a 350 sbc as it is what I am most familiar with. The power band range I am looking at is 2000 to 6500 rpm. It helps keeps parts cost in check.

[b454rat]

Too much gear. Need alot of RPMs to spin the tires fast enough in all the gears farther down the road. Steeper gears isn't always the key. Not for burn outs, but my old car had 3.08s in it. Chipped a couple teeth, so swapped to 3.42s. I hated it. It didn't pull as hard, sucked on the highway, only thing that was marginally better was taking off in 1st on a incline. 461 big block 4-speed 79 Malibu....

[mongocanfly]

4.88 and a 30in tire...4.88 is really low for that dia tire..be good in the 1/8 or1/4
3.50-3.73 would be a better choice

[cadillac_al]

Those are some low gears. Can't you just shift it and burn through 3 gears? You'll probably be changing gears in the near future. It doesn't sound like a pleasant ride with the short gears. Those gears would be fun with a 283 or 305.

[Ziegelsteinfaust]

Originally Posted by cadillac_al

Those are some low gears. Can't you just shift it and burn through 3 gears? You'll probably be changing gears in the near future. It doesn't sound like a pleasant ride with the short gears. Those gears would be fun with a 283 or 305.

It doesn't bother me as a sbc at 3000rpm is perfect to me, and I always have passing power.

I have parts for a hot 302 sbc with a forged crank, and virgin 327 block. It is looking like I may go this way now. Or a comparable 4.8 LS way

[Ziegelsteinfaust]

Forgot to mention.

I blame David Frieburger for this. 5.13's???

No wonder you let us all down, and went to 3.73's.

And I thought I was not extreme enough

[burnin oil]

A little more tire hieght may help. We have 4.88s in the jeep with a 5spd on 32s and love them for its use crawling around the property and going into town. It's not to bad other than faster speeds. 60MPH is about 2500RPM. Perfect for a cruiser that does local runs. It would not be my first choice for the interstate though.

My K20 has 4.10s with a detroit and really doesn't spin the tires without trying. When I want them to churn I turn the wheel a little and stomp it. Once they are spinning you can correct it to go straight or exaggerate the correction and let the detroit keep pushing in the wrong direction. This may help. You may try a harder tire since they don't hook as well. As I got older I spend more time trying to make them hook. Tire smoke is impressive but it's slower and tires get expensive.

[Steeveedee]

It's well known to drag racers that lower gears help with traction control. It's easier to modulate the throttle to keep accelerating without spinning. That's the opposite of what you're after, though.

[Ziegelsteinfaust]

Originally Posted by Steeveedee

It's well known to drag racers that lower gears help with traction control. It's easier to modulate the throttle to keep accelerating without spinning. That's the opposite of what you're after, though.

Damn, that is what I figured.

[mattfranklin]

As I started reading, I thought I'd add a comment about how I'd seen a Freiburger (Roadkill or, more likely, Roadkill Garage) episode discussing that. And now it looks like we've probably seen the same discussion. :-)

[mattfranklin]

At what road speed do the tires stop spinning? That might just be the top end of the engine that you reach more quickly with the 4.88 gears. So either a higher rear gear or higher revving engine. It might be interesting to just keep a spare axle with the 4.88 and one with a 3.73. I'm assuming you still have the stock 12-bolt.

OR... Can you have a manual shift body installed in your tranny (or go in and adjust automatic shift points)? That might give you a chance to have some fun optimizing shift points for max burnout distance.

[Ziegelsteinfaust]

Originally Posted by mattfranklin

At what road speed do the tires stop spinning? That might just be the top end of the engine that you reach more quickly with the 4.88 gears. So either a higher rear gear or higher revving engine. It might be interesting to just keep a spare axle with the 4.88 and one with a 3.73. I'm assuming you still have the stock 12-bolt.

OR... Can you have a manual shift body installed in your tranny (or go in and adjust automatic shift points)? That might give you a chance to have some fun optimizing shift points for max burnout distance.

I do not know the road speed since I have not adjusted the speedometer gears to match the rear. But my guess is around 35 mph.

The 383 torques well with the 116 lsa on the cam, but I think it rev speed is not up to the gear ratio. It would be deadly with 3.73's, and I would of backed the combo with a th400.

I used the stock 12 bolt. My original plan was for a 14 bolt sf, but the 12 bolt is strong enough when built for my shenanigans. This is probably the point where a brand F 9" would pay dividends.

The trans needs a little tuning, but is really close. The trans guy is stupid busy, and I have been busy too. So dialing it in will take some time to get a spot.

The trans was built for the engine in a 2800 pound car before my most recent bout of insanity. So it is on the short list for replacement, and I will be getting a 4L80E soon to inflict my insanity henceforth onto. So I want to save the TH700 for the car again, and not destroy or modify it. So the 4L80 will be built to survive my needs.

I had decided on replacing the motor when I went with the 4.88's, but I thought with the 383 it would be a go to Jesus combo. Meaning my epic death was in short order, and all while unlocking GTA life points.

Right now I am leaning towards a 302 with AFR 185 heads, Victor Jr intake, and a Holley stealth terminator system to also run the 4L80. I have quite a few parts to start, and a good set of solid roller lifters. I have Dart 205cc aluminum eagles, but they are a touch big. The 302 will be more stable at 3000 rpm cruising in OD, and with the right cam. Combined with the gears I do have. Should be more then adequate for my needs. Plus be a touch easier on the pocket book with gas prices right now.

My outside choice is a 350 LT1 with a narrower LSA cam to rpm a bit harder then what a smog legal 383 would use.

The LS is still in the mix, but I can not piece meal it like I can a SBC. So it's all of the way or non of the way. Which changes options in my mind.

[kwmech]

Burnouts with a 700r4?? when the trans gives out post up the carnage

[Ziegelsteinfaust]

Originally Posted by kwmech

Burnouts with a 700r4?? when the trans gives out post up the carnage

It's a level 2 with Corvette servo's, and the stall of the converter buys it a bit of time.

I am hoping to get the 4L80 before I am sweeping it up.

[kwmech]

Originally Posted by Ziegelsteinfaust

It's a level 2 with Corvette servo's, and the stall of the converter buys it a bit of time.

I am hoping to get the 4L80 before I am sweeping it up.

Good choice

[burnin oil]

I love short stroke motors that wind out but I will tell you to forget it right now. Without spending stupid money the pistons are gonna be 11:1 high octane lovers. The heads will work great up top but will suck down low. The combo will need a cam that breaths to use those heads. Total picture is a fun motor that idles miserably and fouls plugs. Running WOT will be a blast but anything else will suffer along with the MPG. It's up to you but I wouldn't do it especially considering the low torque and the weight of our trucks.

No offense on this if it sounds wrong. I think you want a style and truck that roasts tires. Mess up the rear suspension and see what happens. Pull the shocks and drive it. If it spins then add a soft shock that you can tune enoughnto limit axle wrap. If nothing changes add stiffer shock and see if traction is lost. Drag racers spend countless hours reducing wheelnspin so an on doing the same ad you reduce the process. Have you tried raising the tire pressure? Let's be honest, rehearing again is cheaper than another motor.

[Ziegelsteinfaust]

Originally Posted by burnin oil

I love short stroke motors that wind out but I will tell you to forget it right now. Without spending stupid money the pistons are gonna be 11:1 high octane lovers. The heads will work great up top but will suck down low. The combo will need a cam that breaths to use those heads. Total picture is a fun motor that idles miserably and fouls plugs. Running WOT will be a blast but anything else will suffer along with the MPG. It's up to you but I wouldn't do it especially considering the low torque and the weight of our trucks.

No offense on this if it sounds wrong. I think you want a style and truck that roasts tires. Mess up the rear suspension and see what happens. Pull the shocks and drive it. If it spins then add a soft shock that you can tune enoughnto limit axle wrap. If nothing changes add stiffer shock and see if traction is lost. Drag racers spend countless hours reducing wheelnspin so an on doing the same ad you reduce the process. Have you tried raising the tire pressure? Let's be honest, rehearing again is cheaper than another motor.

Yes I want a tire roaster, but the truck is supposed to be rally cross like. They don't have truck classes usually, but more of a way for me to have fun. Plus there are lots of dirt roads over the mountains I can play on.

The 4.88 gears were chosen because I intend to go with a low cubic inch short stroke engine, and rely on rpm more then torque for speed. I was very surprised that with the 383 it would not kill the tires.

I don't need 8000rpm, and I intend to keep redline around 6500rpm as it keeps part cost reasonably low. The 302 I am leaning towards would work great with 4.88's, and play nicer at 3000-3500rpm then a 350 especially a 383. At cruising speed, and not effect speed to much.

I am fully aware regearing is cheaper, but like I said in other post atleast. The engine was a stop gap when I killed the original motor. The 383 will be replaced with a engine I decide compliments my 4.88's best with the tire combo I eventually buy when I do the suspension build. Other parts of the build namely tire height, and suspension mods are in flux. So I need to decide on where I want to go next, and gather some parts. Then engine will likely be after all other planned mods so I have an analog to judge where I want to take the engine combo first.

To understand what I am trying to do look up rally cross races. Or if you watch Roadkill. The Muscle truck shoot out first 1/2 is what I am aiming at. It is not about monster power as your ability to slide the rear end around faster then you can control on dirt is alot easier.

[68Gold/white]

Yeah,Frybuurger spends other folks’ money, way easier for him, than all of us.

All the comments about what you see on TV, used to be all the stuff you read in magazines.
Fryburger came from the magazine world, go figure.

I am envious of him and Finnigan, living out Hot Rod dreams!!

Fryburger just bought a late model Mopar of some kind. My interest in Mopars is a ZERO!!!

[burnin oil]

Funny. I am a chevy guy through and through except for the diesels. Most of the cars I would buy are mopars from the 60s. Guess it's a good thing that I am a truck guy.

[SunSoaked]

This will fix it.

[kwmech]

That'll certainly scatter a 700r4 in nano seconds

[Ziegelsteinfaust]

Originally Posted by SunSoaked

This will fix it.

I am not to keen on selling a kidney for the engine.

Plus if I had that engine.

I would definitely alone.
In a firey crash.
Going backwards.
Into a gas truck.

I am fairly sure I still want to live. As a mere 475hp makes me feel 35 again.