Getting over 4k RPM on a 12 valve

12valve

12valve

Diesel Boy
Joined
Aug 4, 2006
Messages
576
Hello, everyone, long time no posting here.

We will have our first sled pulling event here on may 17th. Most everyone is a beginner, so we will se how it goes.
So we went with a 96 manual dually.
Mods are

Fuel:
Raptor lift pump at 40 psi, 215 pump with 10 Plate and a CDS 5k gsk running
20 degrees timing, spraying through 5x.016 injectors
Air:
II silverbullet at 48 psi boost (filter and 4" exhaust)
Supporting mods:
HD valve springs, DD southbend,

since its a manual transmission, we need to pull in one gear, and im needing more rpms, but its only pulling up to 3200

Ehat am i missing?
 
We where practicing pulling yesterday,

4.10 gears in a dana 80
4th gear low range
yes factory cam
31" tires
 
Last edited:
It will need more timing, diesel is slow to burn your going to have to get it in there earlier. 3200 sounds about right with only 20 degrees.
 
95cummins5.9: you think the fuel plate is limiting RPMs?

how much timing is recommended for daily driving and ocassional pulling?
 
If you want it to pull at 4000, more than a food daily driver tune. Bump it to 28 for the pulls then back it down after. An adjustable pump gear would make it a 5minute job.
 
18 degrees will rev to 4k in neutral without popping under no load, wont make any power there though. Also agree on removing the fuel plate.
 
To get and hold the rpms your after a gear change is what your really going to need. To make the power to turn the rpm your after you will also need more air via a cam swap, ported head, or a combo of both.
 
Don't underestimate what a "stock" 12valve will make on the cheaper side tuned well. Cam and head work is not your best bang for buck where your at. What delivery valves are you running.
 
Stock delivery valves, and stock AFC.

We are at 7000 feet elevation and I want to avoid too much smoke and heat at WOT.

From the video you can see that it's not smoking badly, except at the end where the sled buggs down the rpm... I might need more fuel to have the tires spinning rather than stopping
 
12valve said:
Stock delivery valves, and stock AFC.

We are at 7000 feet elevation and I want to avoid too much smoke and heat at WOT.

From the video you can see that it's not smoking badly, except at the end where the sled buggs down the rpm... I might need more fuel to have the tires spinning rather than stopping
Click to expand...

Like stated before bump timing to 28+ it will be a whole new truck. I wouldn't worry about heat during a sled pull and with that charger its never going to run cool with your fueling.
 
He hasn't said anything about headstuds. If you run at 28deg, you're definitely going to pop the head gasket with stock torqued head bolts.

I'd be very surprised if you didn't.

And I agree on taking out the fuel plate.
AFC mods are free and easy, I would suggest you go through them and get it tuned a bit before the first pull.
 
Bumped timing to 28 today, it doesn't pop anymore on free rev, and goes easy over 4200.
It also pulls harder on top. Thanks for that suggestion!
One thing that's noticeable is that turbo lost about 2 psi boost. Is that a possibility?

The fuel plate has been taken out, and I flipped the washer in the afc and cut the afc arm on the front to alow more travel. what else is suggested to do on the pump?

Cornelius, I later remembered that I forgot to post that mod, so yeah it's got ARP head studs, and traction bars, drive shaft loop, and a lowered bump stop. Boost n pyro Gauges I think that's about it.
 
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