The Sleeper

Been working on this 1985 GMC C2500. It was a totally bone stock truck when I got it. I pulled the 350 out and dropped a 1989 non intercooled 5.9 Cummins in. Drove it around some then blew up the turbo 400 when doing a burnout. I recently upgraded that to a 4L80E with a 1 piece driveshaft. The rear axle is a 14 bolt with 4.10 gears and posi, but it needs 3.54 gears. I just finished up adding a intercooler and a 4 headlight conversion. I still want to lower it and put some fat tires in the rear. Should be a fun truck when finished. Right now, it should be making 350HP, but I have another Cummins with the same VE injection pump that I am thinking of doing a P-pump swap on to get even more power out of.









Velocity ring tucked behind the grille in the existing air intake hole.

 

Good job Nate

 

nice install but where's the bug trap I mean air filter

 

There's a bulge in the piping by the corner of the battery, that's the air filter.

https://www.summitracing.com/parts/spe-9833

 

Took this truck racing a couple of times. I got the transmission tuned properly. Now I need some lower rear end gears! I was topping out at 68MPH.

 

What kind of racing?

 

Drag racing

 

At 68mph? I'm not sure it's a sleeper yet.

 

It's getting there. Like I said, I need lower rear axle gears. At the 1/8 mile, I was ran out of gearing.

 

That Cummins is a lot of weight. Is there a class that your running? What rules would there be.

 

I have seen a built 12v with 6speed drw do a burnout with a loaded gooseneck. They can do some work but you gotta pay to play.

 

I was just doing test and tune. If I was to do any class, it would be bracket racing.

 

I know there is limited space, but, that is a really small filter for a turbo'd diesel application. I suspect a power loss there at higher RPM's.

Can you do a switch to a 68RFE? Would give an added OD gear which would allow you retain the 4.10's. That would give the quickness off the line for racing while the added gear could compensate for the higher highway RPM's.

 

Small? It’s a 4” pipe and a 6” cone K&N. It flows plenty of air for it. I certainly know it’s not running out of power, it runs out of rpm. The engine is governed at 3200, and defuels at 3000rpm.

I mentioned that I’m running a 4l80e, so I already have overdrive. It just really needs gears and bigger tires. The 700ft-lbs of torque will get it going no problem.

 

Sure. Small surface area coupled with getting dirty can restrict flow. Compare to the Tymar 7.3 upgrade


I run a S&B cold air intake (not my choice) on my 6.7. The inlet is 7" with added surface area inside the nose

This runs in an open box with lots of flow.

The 69RFE is a double overdrive which came stock on the 6.7
68RFE Gear Ratio Chart
Gear Ratio
1st 3.23 : 1
2nd 1.83 : 1
3rd 1.41 : 1
4th 1.00 : 1
5th 0.81 : 1
6th 0.62 : 1
Reverse 4.44 : 1
but it doesn't look like it will run behind the 5.9 due to sensor issues.

 

4L80E has a .75 OD gear ratio, with 4.10's that's the equivalent to a 3.07 gear. Am i missing something?

 

Exactly.
Really needs a 6 or 8 speed transmission if he wants to really run fast.

 

As a fan of weird stuff and junkyard projects, I love it.. Bubba approved lol..

 

When I swap engines out to a 12 valve with a P-pump on it, I can boost the RPM up to 4000, which will help a little. The measly fueling capabilities of the VE pump really limit RPM and horsepower.