95' Junker Drag Truck

Drag testing update:

I made it to the track tonight and made 16 passes down the strip.

Best ET was 14.27 @ 102.39 MPH

60' - 2.356
330 - 6.392
1/8 - 9.458 @ 80.8 MPH
1000 - 12.069
ET - 14.270
MPH - 102.39

According to the CompD HP calculator, the best MPH with stock WH1C (HX-35) calculates to 382 rwhp.

According to the CompD HP calculator, the best MPH with GT4294 calculates to 400 rwhp or a gain of 18 HP. This is with identical fueling setup, zero changes.

Pulling up historical weather data from June 16th when I made the best stock turbo run, weather was 88*F, 29.61 barometer, 4% humidity, for a calculated density altitude of 4692 ft.

Tonight during the best run, the weather was 80.1*F, 29.54 barometer, 18% humidity for a calculated DA of 4351 ft.

If you factor in the weather difference, the GT4294 added 17 horsepower vs the stock turbo.


In closer comparison of my 13.68 run vs GT4294 14.27:

Difference at 330 ft .584
Difference in ET .582

The reason the GT4294 is slower is it takes longer to reach full boost.

In the Junker's current setup, there isn't enough traction to hold a 4-5psi boosted launch. When I left at 2-3 psi, it would bog and not spool till 2nd gear. If I left at 4-5psi, it would shake the tires and I'd have to pedal it to regain traction which would snuff out the turbo.

If the Junker had full blown race slicks and good enough track prep to hold a 10 psi launch, I really think it would run quicker with this turbo, somewhere in the 13.2 to 13.0 range.


Huge thanks to Phil Taylor at Diesel Performance Converters for the current torque converter. I removed the off-brand triple disk that was too tight to spool-up and replaced it with this converter from Phil. The converter daily drives almost identical to the older tight one except for at idle where it pushes the truck a little less and on the top end where it lets the truck turn about 200 more rpm.

It's amazing, when I'm at the line, it stalls right at 1700 rpm, and as I keep holding it, the rpm's slowly rise to 1800, 1900, and after about 5-6 seconds it hits 2300 where the turbo comes to life and really starts building boost. If I stay in it, it will make about 10 psi at 2400 rpm before it blows through the brakes.

Thanks Phil, awesome converter!
 
In my quest for more traction, I came across some used roadrace/nascar/asphalt oval type slicks. They obviously don't have super soft wrinkle wall type sidewalls but they do have a good soft rubber compound that should bite the track. Another benefit is these tires should be pretty stable at high speed since they are designed for 170+ MPH cornering and are designed to run without tubes.


Size is 27 x 10 x 15. I bought some cheap used 15"x10" steel wheels a year ago so I should have these mounted up and ready to test out at my next track outing.

Wheels, slicks, and mount/balance I'll have about $150 into the set of (2). Last time I checked, it's about $450 for a set of drag slicks plus wheels, mount & balance.
 

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Awesome comparison man! Glad to see you were able to get that thing spooled with the new converter. Hopefully those new tires and wheels will fit over the rear drum so you can get some good traction and leave with alitle more boost. What is your peak or average boost you were seeing while running down the strip?
 
TTR 21 said:
Awesome comparison man! Glad to see you were able to get that thing spooled with the new converter. Hopefully those new tires and wheels will fit over the rear drum so you can get some good traction and leave with alitle more boost. What is your peak or average boost you were seeing while running down the strip?
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Average boost running down the track is 40-42 psi with the wastegate line clamped shut. With the wastegate line open, it runs 36-38 psi. This Garrett GT4294 has a huge 1.28AR wastegated exhaust housing. I am satisfied with my back-to-back testing with identical fueling, next trip will have more fuel either 5 x.018's or possibly just try out full cut DV's. Depends on how the truck runs with with these untested 5x.018's I bought from Jerrod Glover about a year ago.


lextalionis said:
wont a 15 inch wheel be too smal to fit over the drums in the rear?
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I will have the grind the drums just a little bit. I tried to dry-fit the wheels a few weeks ago and they were really close to fitting, close enough that they would probably mount right up with a 1/4" spacer. One advantage of running a steel wheel is that the wheel itself has a larger inside opening for the drums than an aluminum wheel.
 
Big Blue24 said:
Average boost running down the track is 40-42 psi with the wastegate line clamped shut. With the wastegate line open, it runs 36-38 psi. This Garrett GT4294 has a huge 1.28AR wastegated exhaust housing. I am satisfied with my back-to-back testing with identical fueling, next trip will have more fuel either 5 x.018's or possibly just try out full cut DV's. Depends on how the truck runs with with these untested 5x.018's I bought from Jerrod Glover about a year ago.




I will have the grind the drums just a little bit. I tried to dry-fit the wheels a few weeks ago and they were really close to fitting, close enough that they would probably mount right up with a 1/4" spacer. One advantage of running a steel wheel is that the wheel itself has a larger inside opening for the drums than an aluminum wheel.
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Hmm that's interesting, I have 15x10 rims mounted on my truck as we speak... Those asphalt tires will help quite a bit, but they will still hop pretty good if you break them loose.

Can't you find a smaller housing for that GT4294???
 
I bought a smaller housing for off an S400, we'll see how much machining it will take to make it fit. I'm not terribly excited to spend $350 on a Garrett housing since this turbo is not the end goal setup, it's just bolted on cause I found it cheap and I wanted to do a little testing.
 
It took about 45 minutes of grinding with a small 4-1/2" grinder to trim the fins down on the rear drums to provide clearance for the 15"x10" steel wheels.

The used 27x10 road race slicks are really short but they seem to have great traction, even at 32 psi where I ran them last night.
 

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npe3484 said:
Those wheels look way to nice to go on the Junker! LOL
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It's just camera magic! They are old chromed steel wheels that were probably originally purchased for a rock crawler project. One of the wheels has a little white overspray probably from the garage it was stored in.

I paid $40 total for all (4) wheels or $10 per wheel for the mathematicians on the site.

When I say I've got $150 total into the "homemade" racing slicks, I mean it. $105 for the used tires shipped to my door
$20 for (2) wheels
$25 for the mount and balance.
 
I ran a little bit quicker tonight but nowhere close to where it should run with the current modifications.

First off, the new tires hook up ok, they are grippy enough that I can't spin them on dry pavement unless I build boost against the converter for 8-10 seconds and then let off the brakes. Best 60' of the night was 2.337 no horrible but no better than stock turbo with street tires and decent track prep. There was no track prep tonight and the first semi-boosted launch was after the track had been oiled down a couple times so there wasn't much traction available regardless of setup.

I installed the 5x.018 injectors before heading to the track and they run really well on the bottom end but sputter and pop right at 2800 rpm. Problem is, this turbo barely gets going till 2400 rpm so there isn't much of a useable RPM window.


I improved a little on my best ET that previously was 13.68 @ 100.8 with stock turbo and 215 injectors.

Tonight the best pass was:
13.54 @ 105.78 MPH The new MPH calculates to 442 RWHP and compared to stock turbo and 215 injectors, the truck is making an additional 60 HP.
 

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lextalionis said:
wont a 15 inch wheel be too smal to fit over the drums in the rear?
Click to expand...

Big Blue24 said:
It took about 45 minutes of grinding with a small 4-1/2" grinder to trim the fins down on the rear drums to provide clearance for the 15"x10" steel wheels.

The used 27x10 road race slicks are really short but they seem to have great traction, even at 32 psi where I ran them last night.
Click to expand...

They will fit in stock application....but you have to have a BIG screw driver and BFH to knock the drums back out of the wheel because they come off with them!LOL

[ame="http://www.youtube.com/watch?v=-YVPUnyn22I"]http://www.youtube.com/watch?v=-YVPUnyn22I[/ame]
 
Big Blue24 said:
As cheap as I'd like to be with this Drag Truck project, I couldn't stand driving 100 MPH at the track with 3-4 year old ratty mismatched front tires. I dropped $200 and bought a new set of front tires: General Grabber UHP 225/70/16 with a nice (H) 130 MPH speed rating. Over the previous 245/75/16's, the new tires dropped the truck 1.5" at the front bumper where I measure before and after.
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How are these tires treating you? I know you're using these on the steer axle, but can anybody tell me firsthand how they do traction wise? I'm thinking of buying a set of the same tread for my '94.
 
They steer fine, they ride nice. The old tires were so bad, it's hard to give fair feedback because almost any new tire would ride 100% better than the 5-10 year old heat cracked, cupped, unbalanced junk that came on the truck.
 
I had planned to attend the Wednesday night drags this week but the event was canceled due to rain. Imagine that, it hasn't rained in the northeast part of the Las Vegas Valley since February and it finally poured on Wednesday.

I replaced the old mechanical lift pump with a new genuine Cummins lift pump. While I had both pumps out and on the bench, I took a few pictures and measurements. The old pump that I pulled out was a Carter, not sure if it was the OEM part or if it's a replacement. The new pump actually has a Cummins logo molded into the pump.

Cummins on left, Carter on the right.

 
Once again Cummins on left, Carter on the right. This valve is a one-way valve at the top of the lift pump, basically the pump pushes fuel through those 9 small holes and when the pump resets for a another stroke, the neoprene/viton looking rubber flap does not allow fuel to come back through the holes so it maintains a somewhat constant pressure.

LiftPump010.jpg


LiftPump009.jpg
 
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