GO 4LO

Hey, guys,
I've seen on a few posts that it's not recommended to run any bigger than a Mach 4 with the HO VP44. Why is this? I understand the HO pump reaches its fueling limit in the 550hp range, but will running bigger injectors cause problems of some kind, or is it just not recommended because you get no more performance for your money with M6's than M4's? TIA.
Chris

Don M

It wont hurt anything at all using a 6 on the HO pump, but you wont gain any HP over a Mach 4 ON THE DYNO. Now, that being said..we have plenty of guys running 6's on the drag strip and the sled pulling track. The sled pulling trucks really seem to like the 6's and the HO pump combination.

If you dyno the truck with 4's and 6's...the result is the same HP. Perhaps more TQ though. The HO pump is simply out of fuel.

For a guy buying new injectors with an HO, I always say to use the 4's for high powered apps.

Don~

GO 4LO

Thanks for the info, Don! I'd bought some used Mach 6's awhile back and was hoping it would still be okay to drop 'em in once I've got the money for a turbo. Should be done by summer, I hope - I'll post dyno sheets .
Chris

PourinDiesel

So DON your saying there is more power to be gained on the SLED Pulling track that you won't see on the DYNO??

Don M

No Justin, I am talking about "PEAK" HP numbers on the dyno. Peak numbers dont tell you what is inside the power curve. Inside the power curve we can show more HP and more importantly like I said above, more TQ.

Peak will remain the same. Sled pullers that have gone from a 4 to a 5 and ultimately to a 6 report better performance pulling. Why? The power curve is fatter, broader, etc. Same peak power though. Most guys who drive on the street and dyno are looking for a peak number at a dyno day and may not understand why the 4's and 6's show the same HP and get upset when they paid for 6's and got the same peak number their buddy got with 4's.

Make sense?

Don~

PourinDiesel

I knew I would get a rise out of you!

Don M

HOHN

It's hard to say since so many people have different places where they draw the line of "need" for a turbo, and are content to run around ridiculously overfueled.

If by safe you mean "perfectly safe" then a Mach 2 is safe assuming that you aren't running around with the box on kill all the time.

jlh

Mike Holmen

Don, why doesn't the mach 6er's injectors show an improvement with a hot rod VP pump or a truck running a P pump. I could be off base but are you injectors designed to run lower injector tip pressure (stock VP pump trucks). Once you increase the injector tip pressure (volume) the spray pattern is must be changed enough so that you no longer get a clean efficent burn inside the cylinder???
Hopefully you have race injectors that are design to run on a P pump or a hot rod vp pump.

Don M

The hot-rod VP pumps work good with 6's. 617 HP uncorrected so far.
The non hot rod pumps make a bit more peak HP but is behind in lower rpm band power. Im certain that with some tuning the 617 HP truck could have made more.

P pumps can use a 6. Some other enhancements and parts are needed though. I am machining some parts for the conversion injectors in the next few weeks. Even though, I try to keep guys from the conversions. They drive like crap and need a too much timing to make big power and with high timing they drive like crap. Smokier too.

The nozzle design is not the problem. The design can be used with all the pumps, but is dialed to the SO VP-44.

Don~

Mike Holmen

Cool stuff. Don as long as get a set ready for my next engine that my next engine that I've been dreaming about. Another dumb question, does any body make a stroker crank for the 5.9 engine? If you can make 800rwhp out of 360inches imagine a 400inch motor with a killer P pump with a set of injector made for a 24v. I can see some 12v guys starting to give us 24v'ers a second look.

HOHN

Though it's OT, stroker cranks have been discussed on here before. Stroking such an undersquare engine probably won't give you much in the way of HP.

Try a search for a thread called "borin' and strokin' a Cummins". Don M and I discussed a bit in that one.

Now DE-stroking, hmm-- THAT might be a step in the right direction. Or maybe just longer rods?

Anyhow, there's a lot of improvement to me had in the airflow department (via ported heads, larger cams, better turbo(s), etc) that would give you more value added than messing with trying to stroke a CTD.

JMHO

jlh

trailrydr9

Can one gain more hp if they have an aftermarket pump to flow better pressure, (ie. FASS pump)?