what cam and mods to tow

[Don Baker]

have a gmt400 c3500/2 wheel drive/4 door/dually//eng in the 7.4l TBI.it has the vortec supercharger on it with stock exhaust Y pipe into 3" pipe to a flowmaster 3" inlet and duel 2 1/2" outlets[converter has been removed]4l80e trans with a gear vendor overdrive behind it to a 4;10 rear end../225/75rx16 tires;;;need to use truck for towing only but my race car trailer is 7500 lbs empty;;
what be my best cam choice and what other mods and things needed to get my truck to tow better?do not want to remove eng and do a full build;;already done the major tune up with upgraded wires/dist/msd coil..this truck can not tow my trailer over the hills I have to tow over;;real big pig//I did noticed that I can not find a 02 sensor anywhere on truck and having not found a wire plug for it except on driver side in harness going down firewall behind brake hydrobooster to rear of truck I did find a single wire but has no plugin on it but could have been burnt off or cut off..not sure it is the 02 sensor wire or not;;best I found out was the 02 sensor goes in left side exhaust manifold;;mine has a hole in it but past owner plugged it;;took plug out to install 02 sensor but hole in manifold is way to large for the 02 sensor;;only thing I can think of is maybe past owner changed out the exhaust manifold for one that had a egr tube that went into that hole;;i'm guessing because with no 02 sensor could be some of my no power to tow issue also...even if it is I still want to do what ever upgrades[mods]to get truck to tow better;;

 

[RDF1]

Is the supercharger intercooled?
headers would help a good bit if they are available. Ive never looked into options for the 454.
Know what tune it has?
Wideband?
How much boost?
What year is it?

 

[90halfton]

Stock it should have adequate power to pull 7500 over a hill, unless you're climbing the side of a building. You should have an 02 sensor on drivers side manifold. I would rule out systematic flaws before throwing parts at a blown big block that can't pull a "light weight" trailer.

 

[Don Baker]

supercharger is not intercooled;;
as fare as I know it is still stock tune;
not sure on boost..haven't floor the truck to see how much boost it has;;I know it has a vacum operated boost dump between the outlet of supercharger and TBI hat;;when it has vacum it dumps air[boost]out of it;;if you get on truck where you loose vacum the dump valve closes and sends full boost to TBI hat;;it has a brain box under dash that sends signal to 2 extra fuel injectors mounted on spacer between TBI and intake and has a inline electric fuel pump that also turns on to provide more fuel;;
as to wideband;not sure what you mean on it but i'm thinking you talking about a wide band 02 sensor;;if so..as I stated in post I can not find a 02 sensor so they must had removed it;
year is a 1993

 

[RDF1]

Non intercooled and towing can't be good. Intake air temps rise fast and if it is a stock tune I don't see how it doesn't grenade.

You run 93 octane?
Yea wide band oxygen sensor to see what it's doing.
Should be mandatory on any boosted setup.

I'd bet it's silly rich and very low timing = no power.

Sent from my SAMSUNG-SM-G870A using Tapatalk

 

[Don Baker]

I went on the supercharger web page and they said there superchargers are set up where they don't need intercoolers..yes I run 93 octane;;as of right now there is no 02 sensor on truck at all;;I have a bosh 4-wire I was going install but hole in manifold is way to large so going need to find correct exhaust manifold or do headers that has the 02 sensor bung in header;;
yes running very rich and has no power at all;;when I removed plugs to remove left side exhaust manifold they rank with gas smell

 

[RDF1]

They might not "Need" a intercooler. But when IATs get so high your not making any more power than N/A. That and running Pig rich, your going to have problems.
I would get a oxygen sensor bung welded in the exhaust somewhere. It doesn't have to be at the manifold, anywhere that is convenient.
Once you get an idea what your fuel is doing, then you can go from there.
Ive worked on poor setups that would peg a wideband gauge past 8s and made no power. Tuned them correctly and made a huge difference.
Im not sure how the older 454s are setup but on a LS engine i always shoot for 11.2 AFR for boost. If it pegs the guage then your going to need to do something.

what is the brain box under the dash? does it have any hoses going to it from the supercharger?

 

[Elroy]

ditch the stock Y pipe, magnaflow makes a stainless replacement with the O2 sensor mount and its bigger dia. i think stock is 1.75 in at the manifolds and MF is 2.5 to the muffler, or go custom

 

[Supercharged111]

ditch the stock Y pipe, magnaflow makes a stainless replacement with the O2 sensor mount and its bigger dia. i think stock is 1.75 in at the manifolds and MF is 2.5 to the muffler, or go custom

He has a 454, I assure you his head pipes are not 1.75". OP if you have stock manifolds and exhaust that is hurting you, but not as badly as the tune. That centrifugal of yours is not ideal for towing as it requires some RPM before it'll start helping. TBI heads also suck donkey balls.

 

[Iowan]

Mid tube headers, maybe a straight through muffler, cross over, and a dump that shortens up the exhust some. With the O2 about a foot past the manifold or header is what I heard. A intercooler will help a great deal. Porting the heads to flow more.