3500 RPM shut off

[Outlaw]

I'm new to the diesel world. Ive got a 2006 2500 4wd that I use for towing a race car. The truck is all stock. I noticed that the engine shuts off at 3500 rpm, and the shift points are at 3100. I was wondering if anyone has Tried moving the full throttle shift points up, and the rev limiter accordingly. It doesn't need this for towing, but the occasional full throttle romp feels like it would like a little more rpm. I'd like to hear pro's & con's. Deffinatly don't want to hurt anything.

Thanks in advance,
Roger

[GeneralTJI]

I rev mine to 4000 in 4th gear (to avoid beating 5th/6th, the stock Allison doesn't like doing WOT 4-5 5-6 6-5 or 5-4 shifts with a hot tune)

The stock cam and heads are actually pretty decent and will flow and make power at a higher rpm, but not with the stock turbo.

I setup mine to shift at 3500 in other gears to keep the torque down some.. I can hold my airflow up that high, but after it starts dropping off (turbo won't hold boost).

With the right turbo setup you could rev beyond 3500 and make big power (this could require better valve springs though). You have to change a handful of maps to get proper fueling at higher rpms over stock, you might experiment with shifting it at 3300 and fueling out to say 3500. Torque numbers will be slightly down, but should be able to maintain HP (slightly easier on the trans). Defueling might take some tweaking to get right again.

[turbo4.5]

the truck stops making power at 3000 to 3100 why would you want to go any higher?

[GeneralTJI]

the truck stops making power at 3000 to 3100 why would you want to go any higher?

Mine flows more air at 3300 and holds it to 3500 before starting to fall off. Butt dyno agrees. Could be an error in the MAF scaling but the power feels strong until 3500. Even though boost is dropping, actual airflow can still maintain or be higher.

You can change the power around with the tuning... because I'm not pushing my turbo for all it's worth (stock trans) I can hold good power up higher. When pushing the turbo to its limits I can see where power may peak lower. So it depends on the setup and what your looking for.

Many guys running twins or bigger singles make peak power much higher than 3000-3100... so there is another reason to rev further.

Also, if you can make your HP at a higher RPM, your TQ numbers stay lower which is slightly easier on the driveline. Just depends on what your after.

Something else to consider... when I launch in 4x4, even at 10psi... the truck is climbing in boost as it revs through 1st gear, so I rev mine a little higher. Does this actually make it faster through the 1/4 to get the boost up before shifting? I don't have any data to say one way or the other, but I do prefer it this way.... just some thoughts on the subject.

[turbo4.5]

i have a 04 duramax that i tuned on my dyno with stock turbo. It has the stock air box with a 5 inch exhaust. i built the trans with 5 disc lockup convter. when i dynoed the truck made 407.3@2896 hp 865.7@2208 the boost fell off at 3050rpm. the boost was 24psi i see no reason to go any higher than 3200rpm WITH STOCK TURBO. when you upgrade turbo or run twins your talking about a whole nother beast. when boost fell off WITH STOCK TURBO egts went thru the roof.

[mecanicman]

There are other things to consider. A good CAI and exhuast will increase the rpm you can make/hold boost. Altitude you live at also has an effect. The duramax model you are using also has a bearing, the variable vane turbo models are capable of more. Based on turbo4.5 results, I would guess he is running a LB7. At my altitude with good supporting mods I have been able to hold boost till a little past 3400 rpm on an lb7. While this may not sould like a lot, you sure feel the differance of the extended rpms when passing! As stated, you do not want to shift past 4th gear like this as 5/6 will not take it. It is probably harder on the trans period, but the ones I have done are still alive and kicking(with an initial warning to the owners that their foot controled their transmissions life).

[GeneralTJI]

Speaking of revving to 3500... here is a video of my truck shifting at 3500.

Open in youtube, it has 720p and you can see the speedo better.

http://www.youtube.com/watch?v=2JQZAO2z0N0

[ajamesbond007]

Nice video bud! I have to say I also enjoy the amount of gauges, the radar detector, and gps. I am surprised you dont have a CB in there as well

Have you dynoed that tune?

[GeneralTJI]

Nice video bud! I have to say I also enjoy the amount of gauges, the radar detector, and gps. I am surprised you dont have a CB in there as well

Have you dynoed that tune?

LOL!!! Actually I do have a CB.. just mounted down lower and somewhat out of site (unlike everything else )

Thanks for the comments... never dyno'd

Guessing 430 or so (Mustang dyno) whp based on weight (a little weight reduction) ...Maybe more... Educated guess would be that it would trap 100-101mph IF I let it shift itself into 5th instead of letting off completely, then getting back in it.

[ajamesbond007]

Especially for being high altitude, pretty sweet acceleration

I made a high horse tune using efi live, and am going to convert it to HP here sometime. Do mind if I shoot you the tune to look over and give me some feedback??? I am pretty excited about it as it has done well on my buddy's LBZ. And I am glad there are at least some diesel fanatics on HP tuners... I am anxiously awaiting support for the Powerstrokes as it will help us HP guys out considerably in the diesel market.


Let me know!

[GeneralTJI]

Be glad to!