Let's do some bench racing

97BambiBasherPSD · May 20, 2014

Now I'm just curious here but can the 7.3 break the 800hp fuel only barrier? I see thuglike is at 700 with 250/200s and a Garrett turbo yet mike o is at 717 with 400s and compound turbos. I get it's all tuning but can we go higher? Obviously there is something that I am not seeing as to why the setups are so different yet at same power level. Anyone care to elaborate for me? What's the limiting factor other then the heui is slow? What can be done to make more use of our fuel?

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backwoodsboy · May 20, 2014

Headflow is another knock against the 7.3 from a performance standpoint.
Even with all the porting/polishing in the world we are still at the mercy of having 2 valves per cylinder.

97BambiBasherPSD · May 20, 2014

How much will opening up the heads help? Anyone tried bigger valves?

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NyCowboy87 · May 20, 2014

backwoodsboy said:
Headflow is another knock against the 7.3 from a performance standpoint.
Even with all the porting/polishing in the world we are still at the mercy of having 2 valves per cylinder.

That is absolutely no excuse. The benchmark for light duty diesel performance, the almighty 12 valve cummins, only has 2 valves per cylinder and everyone knows what numbers they can lay down.

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bruce · May 20, 2014

I guess that's why swamps does so much r&d on heads and cams

Hotrodtractor · May 20, 2014

Its simple injection efficiency. Improve the quantity and the quality of the fuel and doors open, birds sing, you find your true love, etc....

Sure - there are other improvements that can always be made such as headflow.... but guess what:

YouTube Video

That has the inner runner restrictions that we do..... It just brings to home the issue even more. The problem is in the fuel side. Its great for what it was designed to do and it has been made to do a lot of things that it wasn't intended to do.... but that is the problem.

And yes - I do believe you can break 800 on fuel in a HEUI truck.

NyCowboy87 · May 20, 2014

Exactly, you never see or hear of someone with a 1,000hp cummins that is doing it on a stock cam and head, yet here in the 7.3 world it's common to see someone do a build and run a stock cam and heads or only a mild port job. A nicely ported 12v and 7.3 head flow dam close to each other. There is no reason, other than the injection system and electronics that a 7.3 has, as to why we can't make the same power as everything else does. I agree with hrt that a 7.3 is more than capable of breaking 800. I wish I had dynoed my triple setup, I truly think that was close or at 800.

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backwoodsboy · May 20, 2014

NyCowboy87 said:
That is absolutely no excuse. The benchmark for light duty diesel performance, the almighty 12 valve cummins, only has 2 valves per cylinder and everyone knows what numbers they can lay down.

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I'm aware that the 12v only have 2 valves per cylinder. They also have a much more efficient means of injection.
The OP asked what factors other than HEUI being slow is limiting power. I think comparing our heads to the heads of another HEUI engine (like the 6.0) is more apples-to-apples than comparing it to something with a p-pump (even if they still have a more efficient injection event than us).

Hotrodtractor · May 20, 2014

backwoodsboy said:
I'm aware that the 12v only have 2 valves per cylinder. They also have a much more efficient means of injection.
The OP asked what factors other than HEUI being slow is limiting power. I think comparing our heads to the heads of another HEUI engine (like the 6.0) is more apples-to-apples than comparing it to something with a p-pump (even if they still have a more efficient injection event than us).

That is kind of like buying a house that burned down to the studs and asking if a new coat of paint will make it livable. Ignoring the real problem doesn't do much good.

TyCorr · May 20, 2014

Hotrodtractor said:
That is kind of like buying a house that burned down to the studs and asking if a new coat of paint will make it livable. Ignoring the real problem doesn't do much good.

Arent the blocks a little iffy up over 600 hp?

Hotrodtractor · May 20, 2014

TyCorr said:
Arent the blocks a little iffy up over 600 hp?

While its true that there are casting issues that are not prefered for making power - I maintain that most of the issues with stressing out a block and watching it split apart, bending a rod, failing whatever.... is all related to a long and inefficient combustion event. Better combustion control of the amount of cylinder pressure and shape of the pressure curve can go a LONG ways to making ANYTHING live.

Look at some trucks that have made awesome power on stock bottom ends for awhile and yes, they ultimately failed.... but it took them a while. Think Scotty's old drag truck. Think Jelich's rig.

Actually I just installed 400/400s with an S400 based 2.6 pulling charger with a 96mm turbine wheel on a truck with a stock engine.... it lights like a dream. There are still some issues we are working through, but I feel it has the potential to last a season or two of hard hooks on power tracks here in central Ohio.

TyCorr · May 20, 2014

That makes sense Jason. That very point is recurring in discussions where damage to 7.3s occurs.

On that setup you just spoke of, im surprised its not hard to get the turbo spooled.

Hotrodtractor · May 20, 2014

TyCorr said:
That makes sense Jason. That very point is recurring in discussions where damage to 7.3s occurs.

On that setup you just spoke of, im surprised its not hard to get the turbo spooled.

So was I. I expected it to take a bit of work..... once we get a couple of other issues ironed out I will be doing some back pressure monitoring.... I think we need to loosen up the housing. I did err on the tight side to make things easier because its an automatic truck.... but still. lol

golfer · May 20, 2014

Hotrodtractor said:
Look at some trucks that have made awesome power on stock bottom ends for awhile and yes, they ultimately failed.... but it took them a while. Think Scotty's old drag truck. Think Jelich's rig.

just for the record...Scotty's HEUI engine is still in one piece...never had a failure. one cyl got down around 300psi so we yanked it...but it's still on a stand, completely assembled, LOL...

we have 7.3L's with CR inj & 7.3L's with HEUI injection...

annnd FWIW...we didn't recently invest in 5 axis CNC machining equipment for injection system improvements...

Hotrodtractor · May 20, 2014

golfer said:
just for the record...Scotty's HEUI engine is still in one piece...never had a failure. one cyl got down around 300psi so we yanked it...but it's still on a stand, completely assembled, LOL...

Oh - I was under the impression that there was an issue larger than lower compression. My mistake.

ja_cain · May 20, 2014

So it looks like the engine will live longer at higher cylinder pressures with a shorter pulse width when the rod angle is kept within some threshold. I guess it doesn't really need to be a step function but the pressures need to stay below this dynamic threshold as the piston progresses downward. Does anyone actually monitor cylinder pressure or is this something that is modeled or simulated?

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golfer · May 20, 2014

ja_cain said:
Does anyone actually monitor cylinder pressure or is this something that is modeled or simulated?

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we do on every performance engine dyno session, and have for years

ja_cain · May 20, 2014

What port do you use? Do you put a transducer in the glow plug port? Sorry if this seams like a dumb question. I love threads like this, btw.

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golfer · May 20, 2014

yes, the GP port.

We also have heads with port provisions for instantaneous flow/turbulence/pressure drop, etc...very close to the valve(s).

NyCowboy87 · May 20, 2014

TyCorr said:
On that setup you just spoke of, im surprised its not hard to get the turbo spooled.

Not to poke fun at you I'm just using your quote as an example, but this is a factor that has probably played into things as well. These engines ain't a 5.9 cummins, there is a lot more displacement to work with. Everyone in the performance world has based everything on a 5.9, what is a large charger on a cummins is nothing more than a modest sized charger on a 7.3. People need to think about it and put a charger on that is speced to work with the airflow requirements of a 7.3. Look at Travis's truck (moormph) hell 5 years ago he was running a hx82 as a single bushed down to 3.0 and lighting it with an auto. If in fact that had the smallest turbine available from holset it was a 130/94, quite a difference from the 96/88 borg wheel that everyone thinks is huge. Good friend of mine street drove a s469 with the 96 turbine for a few years with no problems whatsoever. Truck was "on" the charger by 2300rpm.

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