Would like some thoughts about improving the power in my truck.

[tyoneal]

Hello:

I have a 1997 Suburban 2500 4X4, L-29 Vortec 7.4, 4L80e, 4:10 posi. "Banks" complete truck kit with headers, 3 inch exhaust muffler, high flow air intake.

It has very heavy steel bumpers on it for wenching, holding extra fuel cans, or pushing another car or truck out of the way, 34 inch tires, 4 inch lift, Spring Helpers/Cheater in the rear. Nerf bars with steps under the doors. Nice rack mounted to the top with 2 wide beam and 2 spot,"Daylighters". Compressor on board 30 ft of Air line and assorted air tools, invertor and on and on.

This is my farm and roadtrip vehicle and has 210,000 miles on it. I have got the box to re-program the engine and the tranny depending on what I'm doing or where I'm going. I also tow a 22 ft trailor to haul my Tractor with a front loader and backhoe or mower.

I think you get the picture.

With the drive train set up I have it is a real struggle to get the truck moving under load, or to get the truck moving at high altitudes.

Should I be loolking for a Eaton style SC, they don't make them anymore that I know of but maybe find a used roots with a intercooler, Procharger, STS Twin Turbo's, or a cam, intake and heads?

Or?

Truck stock was 290hp/410tq I'm guessing now with the improvemnts maybe 380-400hp/525-550tq.

Would like to get torque up to 650-700 ft pounds. HP really doesn't matter. What is the best bang for the buck, given this information?

I look forward to hearing from you.

Thanks in advance,

Ty O'Neal

[Randy67]

With your tire height, a bit more gear would be quite a help. A Eaton would be a good choice to me, should give the most low rpm grunt. Turbos would be my next choice, but I would prefer the turbos up front, not in back STS style.

The heads on the L29 are decent, but you may gain more going to a larger oval port head, either aftermarket or early Mark IV heads (supposed to work on Gen VI engines, just not Gen V ones). Just my $.02 worth.

[tyoneal]

Randy:

Thanks for the input. Where would be the best place to get a supercharger or turbo charging syatem that had an inter cooler for an engine of this vintage?

Thanks,

Ty

[1966longroof]

pro-charger

[Randy67]

Not sure of anyone that has a system per se, Whipple used to make a supercharger for the L29, but it doesn't look like it had an intercooler. Pro-charger is another way to go.

A turbo setup may have to be a custom one, doesn't seem to be any kits out there that I can find offhand.

[tyoneal]

Yes I understand, I haven't seen much in the way of anything current other than a Pro-Charger which is bad = 60-65% increase in Power.

Factory:
L-29-7.4L, 454 ci
Hp = 290 + 29 (10%) + 2.9 (1%) = 322 hp +ProCharger @ 60% increase = 515 hp
Tq = 410 + 41 (10%) + 4.1 (1%) = 455 tq + ProCharger @ 60% increase = 728 tq
Headers and high flow exhaust = +10%
Cool air intake = (WAG) 1-2% maybe
Transmission 4L80e
Rear diff = 4.10 posi
============================
If my math is decent I think those numbers would take care of it. If I needed more I could use a gear splitter or see about going to a 6L80e. I think those are avalable now where you can program. (Source if you have one?) The lower gearing I have heard they have now would really get things moving, but the splitter would probably be cheaper.

I know those number seem really high, but with a 7000 lb Truck + a 11,000 lb Trailer it really takes a lot of grunt to get things moving.

From your understanding is the math correct?

.... and if necessary a 4.56 rear gear would certainly launch the truck faster. I have tried to keep the RPM's down just to see if I can get 9 mpg.;)

Any additional thoughts?

I had originally thought about going with a corvette LS3 with a good torquey Cam, then SC it, just because it is so much more efficient than the Big Blocks. Might be able to buy the complete drive train and get the 6L80e for cheap and programed.

Thoughts?

Ty O'Neal

[Zspoiler]

Check at your local speed shop or 4 x 4 shop for access for those kinds of parts.

[Randy67]

Supercharger numbers look good, it will definitely help out. Getting that much load moving is tough, gearing helps out quite a bit. Supercharger will help more once rolling. The granny gear (6.55 ratio) in my 79 Dually helps out a bunch taking off, and I only have 3.73 gears. It originally had 4.56, not much fun on the highway without OD.

I would stay with the BBC, it will tow better than a LS3, displacement is better, especially with the weight you are pulling. Of course a Diesel would be the best choice.