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600 lbs of TQ possible ??

Mike K3500 said:
I think I have at least what is needed to produce in excess of 300 rear wheel hp without a "tune" of any sort.. I just want gobs of TQ without going to a Cummins.
Click to expand...

I hate to be the party pooper, but if that's you goal you're working on the wrong engine....unless 400 lb/ft counts as "gobs"....

FYI: 400lb/ft at 3400 rpm works out to 258 hp.

(400x3400)/5252 = 258

440 lb/ft gets you closer with 285 hp.

If you want to spin it a little higher:

(400x3600)/5252= 274 hp

How you calculate hp is just simple math.

Building torque is a function of displacement, stroke and cylinder pressures.

More of each or all gets you more torque.

Not much you can do about displacement or stroke in a 6.X.

Which leaves us with cylinder pressures, which is also a bit of a problem in a 6.X engine.

The principles are simple, getting there is not so simple....
 
turbonator said:
modify and run a fly wheel for a standard, its heavy=TQ.
Click to expand...

actaully i am quite serious about this, if the fly wheel was machined to accept the snub on the torque converter, and the holes to bolt the TC to it, a guy could have a 1" spacer cut to go between the tranny and block... the standard flywheel easily weighs 5x the flex plate..... inertia man!!!LOL
 
I would love to see a couple a 6.5s making in excess of 600 ftlb torque. Anything is possible but sometimes these things leave the wallet really flat!
 
L98TPI said:
You ever drop a TH400 torque converter on your foot? A 4L80E's is even heavier. Hopped around for days. OK it was a TH350 converter but my point is valid. :rolleyes5:
Click to expand...

I think he's talking about using an actual flywheel to drive the torque converter..
great white said:
I hate to be the party pooper, but if that's you goal you're working on the wrong engine....unless 400 lb/ft counts as "gobs"....

FYI: 400lb/ft at 3400 rpm works out to 258 hp.

(400x3400)/5252 = 258

440 lb/ft gets you closer with 285 hp.

If you want to spin it a little higher:

(400x3600)/5252= 274 hp

How you calculate hp is just simple math.

Building torque is a function of displacement, stroke and cylinder pressures.

More of each or all gets you more torque.

Not much you can do about displacement or stroke in a 6.X.

Which leaves us with cylinder pressures, which is also a bit of a problem in a 6.X engine.

The principles are simple, getting there is not so simple....
Click to expand...

I just find it hard to believe that 550+ isn't easily attainable... 400 definitely should be a walk in the park, but only a chassis dyno will tell, maybe I'll get to that someday.
 
Mike K3500 said:
I just find it hard to believe that 550+ isn't easily attainable... 400 definitely should be a walk in the park, but only a chassis dyno will tell, maybe I'll get to that someday.
Click to expand...

Well, if you want 550 hp you need to make more than a "gob" of torque.

First, a formula:

T = HP x 5252/ N

T = Torque (LbFt)
HP = Horsepower
N = Speed (rpm)

Lets plug in some numbers:

550x5252/3400 = 849 lb/ft

:eek:

Look at that number - 849 lb/ft!

That's a pretty decent number for even a hot Max/stroke/cummins!

That would be one helluva number from a 6.x, definitely not "easy".

I just can't see the design delivering that, being a tractable daily driver or surviving long if it did.

There's just too many thermodynamic limitations in it. Too much heat into the head, not enough into the piston.

So, lets spin it higher and see if it gets any better:

3600:

550x5252/3600 = 802 lb/ft

802 lb/ft, not much better there either....

4000:

550x5252/4000 = 722 lb/ft

Still a waaay too high a torque number and we're really bumping up against the rpm limits of the design. Especially if you want it to live.

Don't forget, to make these numbers, you're also moving your torque peak to the rpm you need for your HP goals which means you could be looking at some serious compromises lower down in the RPM range where you live every day....you just won't know that until you build it.

Engines keep building HP after the torque peak, but it's a loosing battle. More RPM = bigger HP numbers but your lb/ft are dropping off on the other side of the peak. You make the difference in rpm. But the higher you go, the more your torque drops off and then you're beginning to flirt with rpm limitations....

All Hp is a calculated value, even on a dynomometer. All dyno's measure torque and calculate HP.

The numbers can be worked backwards (as we have see here) to figure out what parameters you need to meet to achieve a desired HP or torque goal.

Big HP requires either big torque or lots of rpm......or a combination of both.

Heath's LSR can claim big HP numbers because the RPM he spins the engine at makes a difference in the formula:

500x5252/5000 = 525 lb/ft

Much more believable/attainable numbers from a "hot" 6.x.

Roughly 100-110 more lb/ft than claimed by GM at the end of the 6.x model run.

GEP now claims 440 from the Optimizers with their support system.

110-odd lb/ft more torque from a knowledgeable enthusiast like Bill (with the experience and resources he has at his disposal) it not unreasonable to believe.

High RPM is how those little 4 cylinder Hondas can make big HP numbers. They can only make so much torque, so they spin the bejesus out of the engine and alter the formula in their favour.

Remember HP is work, work is calculated. Torque is twisting force, force can be measured.

Don't get me wrong, I would like to see a 6.X throw down big numbers, but the ones we're looking at here (849 lb/ft) are just not going to happen without a budget equivalent to the space shuttle. Even with that kind of cash it would still be doubtful.

I'm not trying to be a bummer here, but the numbers are the reality. When they're starring you in the face, it's hard to deny the reality of it.

Figuring out your target is easy.

It's physics and math, nothing more. Those are the rules of the game.

That's why guys chucking out a HP or torque number for a 6.x and adamantly stating it's attainable or they will make it gives me a little internal giggle sometimes. They just don't fully understand the physics of what they are saying.

But as I said, the theory and figuring out the target is easy.

Building the hard parts and getting there is a very different story.....
 
hold on a tick, I may have made a mistake on the dyno and what it measures.

I'm thinking I remember some dyno's that measure the work at the roller and calculate the torque.

either way, one or other of the values is calculated.
 
I understand what you're saying GW, and I hope I'm not living pipe dreams... I was wanting to hit 500 + lbs of tq at the rear wheels, I think or I am hoping that is the fairly easily attainable part and meant surpassing the 400 lb rear mark.

I also thought that HP was just a fictional / calculated number, where as tq is the real deal.

I know there are some members whom have figured out ways to get some impressive fueling out of all the DB series pumps mostly the 2 plunger, but I don't think many have tried, let alone have seen a 4 plunger ( was recently informed about the 4 plunger possibly being able to put out a crazy amount of fuel ) and some are running 3 times the stock boost numbers with aftermarket / knock off turbo's... I was just hoping that all translates into some big tq numbers ( big for a 6.5 anyways ).

I was hoping that with all the components I have gathered / come across, and the combination of these components would work great together making for one impressive 6500 ..

Anyhow I am mostly concerned about making bigger tq numbers because I want to possibly get a 5th wheel and want to be able to haul it without a breeze.. and not have to consider a cummnis swap, to do it.

I appreciate your honest input,
Mike
 
Well, like I mentioned torque is a function of a few basic things:

Piston area, crank offset (stroke), Cylinder MEP.

The first two are, essentially, displacement.

Piston area is the amount of surface the cylinder pressure has to act upon. More area, more torque. Can't do much about piston area though.

Crank offset (stroke) is the amount of leverage the cylinder pressure through the piston area exerts on the crank. Bigger offset, more leverage. Again, fixed in our design.

Which leaves Mean Effective pressure (MEP), or average cylinder pressure if you prefer. Note that peak pressure and MEP are different things here. Peak is the high point, MEP is teh pressure the piston feels during the power stroke. Peak is instantaneous, MEP is over time. Peak/MEP is pretty much about all we can change in our design.

Effected by cramming more fuel in the engine. Which requires more oxygen. Which requires more mass. Which requires more density. Note I said "density", not "PSI" although there's a relationship there.

Problem is, our engines can only take so much peak pressure before they start popping head gaskets, cracking mains and pretzeling cranks.

Gale Banks Engineering recommends more air first, more fuel later. Those guys usually know what they're talking about and there's a logic in that approach. Most of the traditional engine tweaks work in a turbo engine as a NA gasser (or diesel). IE: bowl work, valve jobs, port blending/shaping, etc. It's all about VE. Then there's the standard Turbo diesel tweaks to throw on top of that. IE: turbo work, CAC, intake path, exhaust piping, etc.

Plus, there's benefits in a diesel over a gasser to working the airflow first. IE: egt benefits.

Other builders like to bring fuel up to the smoke point and then cram in more O2 mass. Then cram more fuel, then mass, then......

Both approaches work, it's just a different way of going about it.

How big a 5th wheel do you want to tow?

My TT is 8500 lbs, 34 feet long and 9 feet high at the airconditioner (about 8 ft at the roof). My modest 6500 has pulled it over 4th of july pass, up vantage highway, in and out of Butte Mt without breaking much of a sweat. Around 55 mph over all of that. Snuggled up to 210 ECT and 1050 F EGT. Lower if I was spraying water.

About all I ran across in my cross continent trip that gave it trouble was Lookout pass. Had to drop to 45-ish mph to keep the engine parameter listed above. But. traffic was moving slower than me anyways so no worries. Confused the heck out of a couple guys when the speed picked up and I could accelerate up look out. If I wanted to push the EGT/ect's higher, I could have gone faster (lots of pedal left) but I wasn't willing to risk the engine or turbo with higher temps.

Flat running with the TT is a larf. Runs the cruise with no issue. Anything else under 65 MPH is just in the way. Unless the winds really come up, then it just works harder but keeps speed.....

In order to reach 400 lb/ft at the rear wheels, you need to make about 10-15% more at the crank (4L80E losses, I thought it was more but Ferminator says that's about it).

So 440 lb ft at the crank.

500 is going to be closer to 550 lbft at the crank.

Those are some pretty high demands for a 6.x. It's going to take high peak and MEP's, a good dallop of fuel and lots of air mass.

The problem with chucking more fuel at the 6.X is the injection design. IE: IDI. Thermally inefficient past a certain point.

Has to do with the amount of heat retained in the head as opposed to being imparted to the piston area. Let's not forget that you also have to get more O2 in there to use that fuel, which brings us right back to the Peak/MEP issue.

There's also "throttling losses" associated with the precombustion chamber "mouth design".

This is a double edged sword; the flat of the piston face induced squish/turbulence to the piston "pocket", which forces the air at high velocity into the pre-cup mouth, which has to be sized smaller to keep the velocity/swirl/turbulence up, to mix the course fuel spray from our low pressure injection system, to aid faster burn, to get more power and cleaner emissions.

But:

Then it all reverses and the mouth that was so beneficial in velocity, turbulence and swirl becomes a hindrance in getting the fuel back out into the cylinder. Pressure builds in the pre-cup, which forces the charge out the mouth to combine with more O2 in the cylinder, but the mouth restricts the flow, which hinders the charge exiting, which soaks up heat, which goes into the cooling system and is not imparted to the piston area, which reduces MEP, which limits torque production.

Where's the balance point?

Dunno.

What's this mean for you?

Meh, keep going, see what you get.

Not much else you can do except get back in there and start blending, grinding, porting and matching.

I wouldn't want to pull it all apart again for that though, if I were you that is....plus, unless you know what you're doing with that stuff you can end up with a negative gain (IE: you "F" it up!)

I hope you reach your goals, but I'm a bit skeptical of 500-ish rwtrq in a dependable towing application. 400 lbft seems a more likely target.

(whew, my brain hurts now......)
 
Hi Mike, Check this out......Diesel Power magazine March 2007.

These are #'s from GM;
6.2L 143hp @ 257 ft/lbs(max from GM)
6.5L 215hp @ 440 ft/lbs(max from GM)
6.6L 365hp @ 660 ft/lbs(max from GM)

The Duramax (6.6L) introduction, was 300hp@520ft/lbs, these are very close to the exact #'s that John got on a dyno with his 304rwhp and 525 rwtq. Although the #'s from GM were at the crank, not at the wheels. A simple correlation can be used to see clearly that 600ft/lbs at the wheels is not that far off. All the calculating can be done to have an idea of the outcome, but it is real world data that will tell the story.

I am sure that this thread could also denigrate into an argument about the accuracy of the many different dynos avaiable too.
 
Here's another for you......228hp@376ft/lbs. This is another 6.5L dyno results, 95 truck with Heath tune and GM-X turbo. He is actually quite close to 400ft/lbs at the wheels.

With your set-up, when all dialed in, should give you over +300hp@+500ft/lbs. But what do we know any ways. Usually we take all the information and opinions on these sites, sit down with a couple of coffees and make our own decision anyways. Do not even desire to count all the times we thought the experts were full of it, then did it our own way and it works. Must be the sprinkling of the pixie dust combined with unicorn sh*t that we use.

This is not to say we do not make mistakes, but we do research, ask questions, and do our calculations to arrive at our decisions.

I hope that as you reflect on your past 4 or 5 threads, that you realize that you are going against the grain. Hats off to you man, get your truck up and running, we will take up a collection to insure that you go get the dyno done. On the site "Powerstrokenation", they have dedicated a thread specifically for IDI dyno run sheets. Would like to see your truck listed there.
 
GW, I'm curious to know all the upgrades you have on your Optimizer... turbo, injectors, exhaust, IP and not for any particular reason, just out of plain curiosity.

Both you Turbonators, I really appreciate all your enthusiasm and encouragement, I really wanna believe that I can, at the very least hit the a fore mentioned numbers 300 / 500+ but we all know it's gonna take some time at the pace I work on this thing.. LOL. Seems like sometimes I definitely spend more money then wrench on this thing, but I will get it done before next christmas, I promise. ( my boss and the guys I work with give me shit all the time about not having it done yet ), sometimes it's hard to work on it, I occasionally lose motivation.

I also appreciate the offers for dyno time, but I will have that covered when the time comes.

If my current, "in progress" set up doesn't hit the desired numbers, I have some other ideas that should make things interesting.... Just not ready to spend that much more money just yet. ;)
 
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