hey its the man himself. how about just the major mods such as air, fuel and oil and how you get it to the ground?

what about dyno numbers?

 

Greg youve got some catching up to do...6oh's are owning ya! LOL

 

You up and running again yet? Are you going to make it to the July Truck Fest in Colorado. I think I'm going to meet up with Tony and Luke in Kansas for the trip on out there. I'll try to meet up with Terry and Wanda here in Columbia on the way to Kansas though.

 

Mahle .010 lower comp. pistons
HPC Billit rods
Balanced rotating assembly
Main studs
Chrome molly pushrods
Fire ringed heads
Hypermax Hi Rev kit
Head studs
BD code true DT530 singles
BTS HPOP
JNB fuel system
SX fuel pump and modified pickup
Modified Hypermax H2E
Snow Perf. water/meth inj.
TS 2 stage nitrous
Custom tuning by D-P Tuner
BTS tranny
and lots of other misc. stuff!!

#2 only from last year..different motor...in the neighborhood of 560 now



With nitrous from over a year ago....should be 700+ now

http://www.northtexaspowerstrokes.com/users/dockboy/612dyno.jpg

 

Looking at that shopping cart of mods, it gives me pause, especially looking at the graph. It seems most items holding the PSD back have been addressed.

What I wonder is how far the 7.3 can be revved? It seems his is "built" but falls off at the 3500 mark. I guess I was just wondering what the dropoff is at 3500 on his truck. Valve float, fuel delivery, or just an inherent diesel specific design limitation on combustion that prevents really winding the beast? Or it could be a puter code preventing further madness.

I do think those are very impressive numbers, numbers I'll never attain (PMRs). Just wondering what the limits of this engine are.

 

Well, Greg did say that the graph is from last year's motor. Not sure how much of that stuff has been added since then though.

These motors, given the correct parts, can take quite a bit. Mech runs his to over 4000 RPM when pulling - and on stock internals. The chip is what sets the rev limit of the motor, and that can be set to whatever you want. I ask Jody what the rev limit was when I had my truck on the dyno, because it seemed to spin freely up to about 3400 RPM. Jody said he starts to cut fuel at about 3400 RPM and has the hard cutoff at 3800 RPM.

As far as how much power they can take. Well, it seems that the internal parts are the weak link. As long as they are upgraded, the block doesn't seem to be a problem. I've heard rumors that there's a PSD out there putting out over 1000 HP on a stock block. And we all know there are sever out there that are definately putting out around or over 700 HP on a stock block. All with upgraded internal parts of course.

 

It's called letting off the throttle!

I have my rev limiter set at 3800 rpm.

What is reving the motor higher going to get you?

 

I honestly didn't know if there was any benefit going any further. That's why I asked. You seem to be the person who would know so I took the opportunity to ask. Thanks for any insight.

 

I've often thought the same thing. In our motors, being diesel, it doesn't seem that more RPM gains you a whole lot.

 

No Problem

The pullers like more rpm for more wheel speed. Personally, I'm a drag racer. HP is what gets you down the track and higher rpms are not going to get you more HP

 

Thanks. That pretty much answered that. No need going there if there's no benefit. All the postulating in the world won't change that.

 

i have always been taught that RPM's is where the HP is at. a gas motor can turn more RPM's than similar diesel, and that is where they get the horsepower. a Diesel has more torque than a gasser because the stroke is longer, there is more time for the combustion to take place, so there is more force exerted on the crankshaft. that means torque. but when the RPM's increase, HP should increase in a different proportion. the way that so many guys get more HP is because they spin the engine over faster. like the race cummins that spin 5500+ RPMs, they get ALOT of horse power, but less torque because there is less time for the combustion to push on the piston. the formula for HP is torque*RPM/5252. so if you have 900lb ft at 3000 RPM, you'd have about 514hp, which you do. but if you could take and follow the torque curve to about 4250 rpm, you probably would have about 750-800 lbft right? so, you can see that it is about 650hp.

after all that mumbo jumbo, i think that if you wanted to run the engine faster on the dyno (say to 4100 rpm), you could have a lot higher HP number (albeit less torque, naturally) than the HP you have at only 3150 rpm. and, 511hp is incredibly impressive at that engine speed.

 

Well Kris, that's kinda what I was getting at with my post on this. I'm just not as knowledgeable with these diesels as the gassers. I know rules are rules but the math changes with the fuel type I believe. I was just wondering if there was a point of diminishing returns on the tach in the diesel without outside assistance due to it's low or I should say higher flash point. Is there enough time to efficiently burn the fuel at that higher RPM without additional assistance?

 

with enough air (boost) that enters the cylinder, it should. the more air you can stuff in, means that it will make more heat (more compressed air=heat) and it should burn the fuel that does get shot in. this is where (i believe) that HEUI has an advantage here, because injection timing can be electronically controlled. this means that the fuel is shot in sooner, so it has more time to burn. the cummins (that are PT, and are fired by the cam) means that they are fixed. the HEUI can be more efficient at burning the fuel, at the cost of higher cylinder pressures. that is the killer of PMR rods, the fuel actually starts burning before the piston reaches TDC, and the force exerted on the piston only raises cylinder pressures, because the combustion cannot push down on the rod, because the crankshaft is still being turned by the other cylinders firing, and instead of flexing, PMR's like to break. that is why the PMR's do not like to be overrevved. a good rod like a billet one or forged steel will flex some under increased cylinder pressures.

damn, i dont know how i got off topic there, but one thing led to another. sorry.

 

Kris, you are a treasure trove of unbridled information with the enthusiasm only youth can bring. I only wish you had the expense account to go with it because you may well end up with the most modded truck on this forum.

I look forward to your taking the 7.3 to new RPM levels and reporting back that information on the beast from the east.

I would do it but my wife would have me sleeping in the truck. Hmmm