Need Diesel Tech

[BlueCuda340]

Have you done the math on how fast the truck will go with its stock gearing? I had a 99 2wd quad cab short box that would do like 118mph which was max rpm in high gear(5speed). It had an edge ez on it which was like a 65hp boost. But I a. Sure it would have done that or very close bone stock as it was easy.

[DanStokes]

"Cuda - Don't know if you've read all of this thread. Was your truck a gasser or Diesel?

Anyhow - Mine ran 107 then 108 in stock configuration - this was actual speed in a timed mile not GPS or other approximate method. According to the Interwebs the truck has a speed limiter that is nominally set to 95 but I think mine's set a bit high - I don't know if your '99 has the speed limiter. The Edge will bypass the speed limiter as well as add HP.

Haven't done any math yet (I suck at math) but probably should. I need to be sure that I don't go too fast and get booted out of the track. The Edge Attitude readout has a speed display option which I'll compare to the time slip value and see how close it is. I'll use the readout to keep me out of trouble.

Dan

[Russell]

Dan, I will run the numbers for you if you like. Just need the inputs: max rpm, overdrive ratio, rear gear, tire size.

For example
3300 rpm
.80
3.54
265/75/16 about 31.6"
= 109.5 MPH

[DanStokes]

Thanks Russell. We may have to solve some of this backwards. I can measure the tire height and the axle ratio is known, also the MPH in a mile. But I didn't notice the RPM (too busy looking at the track at that point) and I'm not sure of the OD ratio but I bet that will be online somewhere - I'll go look.

A little more info:

The OD ratio is 0.69 (from the Internet).

Rear end seems to be 3.55 but I need to measure it to be sure.

Sitting on the pavement the tires measure right at 31"

Dan

[Russell]

I normally calculate the height of the tire based on tire size. Not sure how close it is.

3300, 0.69, 3.55, 31" = 124.24
3300, 0.69, 3.55. 31.6" =126.65

The rearend may have a tag, mine says 3.54
3300. 0.69, 3.54, 31" = 124.60

May have to up the rev limiter to hit 135
135mph, 31", 3.55 0.69 = 3586rpm

or change the rear gear
135mph, 31", 3.27, 0.69 = 3303rpm

or get bigger tires
135mph 33" 3.55, 0.69 = 3368rpm
135mph, 34", 3.55, 0.69 = 3269rpm

I have a programable calculater that I use. John has a very nice Excel spread sheet that he sent me that does the same thing only better if you use excel let me know I might be able to find it if not John will send it to you.

[Russell]

you can find them on line as well, this one is ok but only outputs every 500 rpms. http://www.wallaceracing.com/gear-speed.php

[DanStokes]

Thanks Russell. The Edge will let me tweak the rev limiter but I don't know if 3500 is safe for the Big Cummins - that's really wound up for a Diesel. Maybe I can borrow some tall tires for the September meet. Can you run 135 on mud & snows?

Dan

[TC]

Thanks Russell. The Edge will let me tweak the rev limiter but I don't know if 3500 is safe for the Big Cummins - that's really wound up for a Diesel. Maybe I can borrow some tall tires for the September meet. Can you run 135 on mud & snows?

Dan

Dan I know there are guys with Duramax's that spin them 6000rpm and higher, I've even heard of guys spinning the Cummins 6000rpm, but then I'm not sure how much machine work and parts that have in those motors to make them live.........

[TheSilverBuick]

I'm pretty sure it's injector limited, not bottom end strength. It'll eventually cap out on fuel delivered.

[Russell]

Thanks Russell. The Edge will let me tweak the rev limiter but I don't know if 3500 is safe for the Big Cummins - that's really wound up for a Diesel. Maybe I can borrow some tall tires for the September meet. Can you run 135 on mud & snows?

Dan

I thought M&S came from the tread design. I ran my old lincoln up to 138 with over sided used suv M&Ss on the back. I would think the load and speed rating would be more important than the tread design. Best to ask one of the Tech guys not me!

http://www.bangshift.com/forum/showthread.php/15169-Lincoln-Mark-VIII/page5

I really miss that car, was like driving a couch, if it had a 5-speed and got 40mpg it would have been perfect

[TC]

The Edge tech guy said that on the Dodge there's no advantage to big exhaust until I get to around 600 HP

That is an interesting statement, because I don't know of an single 3" exhaust system out there that will support 600HP.........

I've always understood that 3" pipe in a single exhaust application was good for 300-350hp depending on engine size.........

[dieselgeek]

I've always understood that 3" pipe in a single exhaust application was good for 300-350hp depending on engine size.........

I think the word is "misunderstood" because I've seen in person (tuned - not "read form a magazine" or "saw on the internet") 750+ whp on single 3" exhausts.

[TC]

I think the word is "misunderstood" because I've seen in person (tuned - not "read form a magazine" or "saw on the internet") 750+ whp on single 3" exhausts.

I'm not saying it can't be done, the question is how much more power would it have made if it had a bigger exhaust??... Also what kind of back pressures were you seeing......

Here's an exhaust pipe sizing chart...........

[dieselgeek]

That chart must be for N/A applications? what I was thinking was a 2.0 liter 120cid engine that made 750whp on a dynojet. 3" exhaust, single. We cut the muffler off and picked up +40hp.

What kind of backpressures was I seeing? this was a turbo engine. Drive pressure likely 2:1, so 50-60psi likely. We don't often measure drive pressure unless we know we're pushing the limits. And when's the last time any hotrodder measured backpressure on an N/A engine, LOL.

[DanStokes]

I'm wondering if that chart is for Diesel applications? Not saying it isn't, just that I didn't see it indicated. With a lack of throttle blade and a turbo I have to wonder if that chart applies.

Anyhow, I likely won't exceed 350HP anyway unless I hit the Lotto and can get the trans built and a nice removable cage installed.

Dan