Need Some Ideas

[JAMIEZ71]

Hey Guys,

I've got the following mods on my 03 gmc w/5.3

 

S&B CAI, Diablo Sport Tuner

Helix Throttle Body Spacer

VR Velocity Stack

Magnaflow 3" Catback exhaust

 

I'm looking for something to add that will give me some more low end torque for pulling heavy trailers here in the hills of WV. I've thought about adding electric fans to boost a few HP and I've also thought about shorty headers but everyone seems to be against them. I don't want to get into major exhaust mods for long tubes. Let me here your ideas and opions. The mods I have now definately made a difference over stock. I installed them all in one day and there was a definate seat of the pants gain. Thanks ahead of time.

[dark knight]

Jamie,

 

I would recommend adding a set of headers. I added headers to my 2000 GMC and it was huge improvement. The headers I put on my truck came from Banks then I coupled it with monster exhaust system. They are not hard to install if you have a hoist and a wire feed welder.

[Stevens03]

Well if it was me, I'd loose the TB spacer, thats not doing anything but making your truck whistle. Since you have diablo, I'd ask diablew to write you a custom tune for your truck to help get all that you can from the tuner. Do some data logging and make sure your LTFT's are dailed in and you'll see a nice improvement from the cookie cutter tune diablo has in there now.

 

Gears.. What gears does your truck have now? Gears would be the next choice. Depending on what tires your running, 4.10s or 4.56's would get you some nice low end grunt.

[music]

What is the application? Pulling highway speeds with 7k lbs, or pulling back roads? WV is about the worst area for pulling on the highways. The interstate pulls aren't steep, but it's constantly up and down, up and down, up and... well, I guess that describes it... all at high speed.

[redvett]

Ditch the TB spacer its just a good paperweight. Go back to the stock exhaust for some back pressure and more bottom end torque.

 

Hey Guys,

I've got the following mods on my 03 gmc w/5.3

 

S&B CAI, Diablo Sport Tuner

Helix Throttle Body Spacer

VR Velocity Stack

Magnaflow 3" Catback exhaust

 

I'm looking for something to add that will give me some more low end torque for pulling heavy trailers here in the hills of WV. I've thought about adding electric fans to boost a few HP and I've also thought about shorty headers but everyone seems to be against them. I don't want to get into major exhaust mods for long tubes. Let me here your ideas and opions. The mods I have now definately made a difference over stock. I installed them all in one day and there was a definate seat of the pants gain. Thanks ahead of time.

[JAMIEZ71]

Most of my pulling is bettween 55-70mph. I'd say 3/4 of it is 2 lane mtn back roads with between 5000-6000 lbs. I already have factory 4.10 gears. I really shouldn't complain about the power that I have because I really don't struggle at all with all that I have and I still manage to get about 11-12mpg pulling that kind of weight. Just always wanting more. As for the TB spacer I don't have a whine or whistle. I've done a lot of mods to the fuel trims and such in my diablo to get everything dialed in where it should be. Everything I have on the truck except the exhaust I bought as a package deal for $500.

 

I don't think putting stock exhaust on would help any at all. Stock exhaust is 2.75" in diameter and the Magnaflow is only 3". That is very minimal difference.

[redvett]

Headers will raise the torque band and the stock exhaust will lower the band. The TB spacer was good on wet Carb or TBI systems to improve fuel atomization but on PFI the fuel is injected at the valve head so no improvement will result.

 

Most of my pulling is bettween 55-70mph. I'd say 3/4 of it is 2 lane mtn back roads with between 5000-6000 lbs. I already have factory 4.10 gears. I really shouldn't complain about the power that I have because I really don't struggle at all with all that I have and I still manage to get about 11-12mpg pulling that kind of weight. Just always wanting more. As for the TB spacer I don't have a whine or whistle. I've done a lot of mods to the fuel trims and such in my diablo to get everything dialed in where it should be. Everything I have on the truck except the exhaust I bought as a package deal for $500.

 

I don't think putting stock exhaust on would help any at all. Stock exhaust is 2.75" in diameter and the Magnaflow is only 3". That is very minimal difference.

[JAMIEZ71]

When you say raise the torque band do you mean raising it in the RPM range or just more torque thourghout the powerband? Shorty or Long Tube?

[Jennabear]

Torque converter....

[Mark_in_Tulsa]

Most of my pulling is bettween 55-70mph. I'd say 3/4 of it is 2 lane mtn back roads with between 5000-6000 lbs. I already have factory 4.10 gears. I really shouldn't complain about the power that I have because I really don't struggle at all with all that I have and I still manage to get about 11-12mpg pulling that kind of weight. Just always wanting more. As for the TB spacer I don't have a whine or whistle. I've done a lot of mods to the fuel trims and such in my diablo to get everything dialed in where it should be. Everything I have on the truck except the exhaust I bought as a package deal for $500.

I don't think putting stock exhaust on would help any at all. Stock exhaust is 2.75" in diameter and the Magnaflow is only 3". That is very minimal difference.

 

That's a 24% increase in volume. That is a huge amount. These engines have a large valve overlap. And because of that they need some backpressure to produce low end torque. Don't think of back pressure as a clog in the system, think of it as more of the exhaust is shooting out faster.

 

Just imagine the same amount of water coming out of a big hose, verses one that has a pointed nozzle.

[JAMIEZ71]

"That's a 24% increase in volume. That is a huge amount. These engines have a large valve overlap. And because of that they need some backpressure to produce low end torque. Don't think of back pressure as a clog in the system, think of it as more of the exhaust is shooting out faster.

 

Just imagine the same amount of water coming out of a big hose, verses one that has a pointed nozzle."

 

Not to question the above but just about every company that designs, test and sell exhaust all seem to have 3" and they usually have dyno runs to prove the gains. Some of the companys that offer single in and dual out even have dual 2.5. That's a lot of flow and they get gains. But anyhow the exhaust isn't something that's going to be changed. I seen a huge difference with all the mods added during one days time. I don't have dyno anywhere near to be able to prove those gains. My truck shifts far less than my buddy's stock truck when pulling the same loaded trailer.

 

Are high performance plugs/wires/ignition something that will help or too much money for the power?

[nickvrebel]

if you want a noticeable difference then do a motor swap. go from the 5.3L to a 6.0L. I'm serious. it's a simple bolt in application, it will even run on a stock tune just fine (although I'd get a custom tune to dial it in correctly). Been there, done that. It's the cheapest way to get the power you are looking for. The only other way to get a noticeable power gain would be to supercharge it, but that's some serious $$$. The motor swap can be done with a low mileage salvage yard long block in one weekend with a buddy and easily for under $1,200.

[JAMIEZ71]

if you want a noticeable difference then do a motor swap. go from the 5.3L to a 6.0L. I'm serious. it's a simple bolt in application, it will even run on a stock tune just fine (although I'd get a custom tune to dial it in correctly). Been there, done that. It's the cheapest way to get the power you are looking for. The only other way to get a noticeable power gain would be to supercharge it, but that's some serious $$$. The motor swap can be done with a low mileage salvage yard long block in one weekend with a buddy and easily for under $1,200.

 

That sounds more along the lines of my funding and such. I may have to check into the 6.0L that my uncle has setting in his basement. I just figured it would be too costly to purchase the parts that would make it work with my tranny and so on.

[Z'06]

I may have to check into the 6.0L that my uncle has setting in his basement. I just figured it would be too costly to purchase the parts that would make it work with my tranny and so on.

 

By all means, use it! There's no replacement for displacement. It should drop in fairly easily. Meanwhile, sell the Velocity Stack and the TB spacer.

 

If you decide not to, however, Jenna mentioned that a torque converter swap would help - you should look into a TrailBlazer converter or a modified one from Circle D. I'm using their 3K-3.2K stall, but to keep your low end with a stock or *very* mild cam you may want to use their 2.6K-2.8K stall. For a cam that will work well on your stock converter, you should look into a cam like Comp's popular 212/218 low-lift cam.

[nickvrebel]

as long as the 6.0L motor has aluminum heads and NOT iron heads it is a direct bolt in replacement.

the cost of $1,200 I mentioned was roughly:

$1,000.00 salvage yard long block motor (reuse your intake manifold, fuel rails and accessories)

~$200 to cover fluids, one or tools you might not have had and beer

 

the 6.0L that was originally bolted to a 4L80e transmissions (HD), but has aluminum heads will have a spacer on the crank shaft behind the flywheel/ flexplate. Take that off and throw it away, reuse your flexplate from the original motor. Re-use the oil cooler block off plate from the original motor. If it was originally in a 1/2 ton truck it's good to go as is.

 

if the 6.0L has iron heads (some 2001 and older) then the crank shaft is the incorrect length and will not work for this application.

 

I've had my hands in 3 motor swaps, one on a 2000, 2002 and a 2004. It should take two competent people no more than a day and a half to get it complete taking their time. I did one with two guys helping that couldn't even pull a water pump before we started and we did it in about a day and 3/4.