More hp, less torque.

[Swamp Donkey]

I was wondering if there was a way to increase hp and not get all of the auto transmission shredding torque. Of course I realize that they are in a way interelated, and is a characteristic of an I-6, but if anyone has any ideas on how it is done, feel free to spread your wizdom... .

 

[Red Rocket]

more hp, less torque

I have an idea, get a powerstroke.



Just kidding, I would never seriously say that. I beleive that the only way to do what your saying is to just simply raise the rpms of the motor. I cant remember the formula, but torque, hp, and rpms are all related somehow. Since this engine is not designed to run much faster than it does, this won't gain you much.



Maybe someone else can enlighten both of us about this.

 

[SLang]

HP = (5252 * Torque) / RPM



All dyno charts have T and HP cross at 5252.



HP means nothing. Torque is a measure of moving the weight. HP is how fast the Torque can move the weight. If the truck has enough torque for your application don't worry about the HP number. Just drive it and love it.



WOW!!! Did I just say that



Edit: Sorry HP = (Torque * RPM)/5252



At low RPM the RPM/5252 ratio is less than 1 shown by low HP at start of Dyno. At 5252 RPM/5252 ratio is 1 so curves cross. At high RPM the RPM/5252 ratio is greater than 1 shown by high HP at high RPM on Dyno.

 

[WKener]

I wouldn't know why you would want to lower torque, but I can understand the craving for more hp. The way you can increase horsepower without affecting torque, is simply by increasing usable rpms, just as RedRocket stated. Go back and look at SLang's formula, which is correct, and just think of torque as low-rpm power. To me, torque is a kind of guage for potential power, assuming you can spin the motor fast enough. That is why you see those little rice rockets that can make 200 or so hp, but only 150ft-lb of torque... they are revving to 7000 or more rpms.

 

[Missouri Mule]

swamp donkey,

It would be easier to upgrade trans with after market components.

DTT or BD.

 

[Swamp Donkey]

I have a bd tc & vb right now, but my DTT stuff should be here later this week. All I was trying to get at, was if everyone was at 300 hp then everyone should be at 700 ft lbs. We know this is not the case, everyone is a little different. So who has a high hp/low torque engine, or fairly low hp/high torque and how did you achieve this? Just high rpms??????? Turbo size, injectors, timing, fuel plate. There is more to it than the answers I have gotten so far.....

 

[Joe G.]

John,



If everyone was producing 700 ft/lb at 1600 (91 HP) then they would show the same HP at that RPM. Now if the torque curve is so that one of these people is producing 600 ft/lb at 2200 (251 HP) and another was producing 650 ft/lb at 2200 (272 HP) their HP numbers at 2200 would be different even with the same max torque at 1600.



You might want to fool around with some numbers at:





http://www.ihonk.com/h/speedcalculators/engine1.html

 

[tmarti96]

HP v Torque

Slang, your command of the English language as it relates to Dodge Cummins continues to amaze me. Keep it up. I love it.

 

[SteveH]

So far no one has mentioned how the vehicle gets the horsepower to the wheels as being a factor. An auto transmission uses more of its flywheel HP to get power to the wheels than a manual does. Rear wheel HP is quite different than advertised flywheel HP. A badly designed torque converter could cost you dearly in HP and in torque. Some torque converters are designed for low end, some for high end torque. There are so many different factors to contend with, I'm confused now!!

 

[Swamp Donkey]

Back to my original question. A stock 24v has 235/460. A 12v with a TST 230/605 plate makes 145 more ft lbs of torque while producing 5 less hp. Even a stock 215 hp truck with about 460 ft lbs of torque can have an increase of 145ft lbs with only a 15 hp increase with a 230/605 plate.



How, or can it work in the opposite with big hp and not so much torque? I still think it can be done, maybe it is top secret and no one wants to tell!



I know how I can get the answer to this, call one of the venders on the TDR with my Visa!

 

[SlyBones]

I think they did give you an answer. The formula above holds true. This would be my guess.



While a 215/440 and a TST plate will give 230/605, you need to keep in mind RPM's. The TST plate took you from 215 to 230 at 2600 RPM's and from 440 to 605 at 1700 RPM's ( for example ). The formula holds true and you can reverse engineer the numbers. While you only got a 15hp increase at 2600, you probably got a much larger HP increase at 1700 resulting in the huge torgue gain. -- What the plate really did was give you more of a flatter, wider powerband and less of a narrow, peaky powerband. And a slight increase in the peak power level.



Maybe what you are asking for is a narrow, peaky powerband. Seems like you are asking for something that gives you an increase at 2600 rpms, and very little power increase down at 1700 rpms. Or maybe even something that helps reduce power down at 1700 rpm, while giving a boost at 2600.



Not sure of what you will buy to get these results. seems to go against the nature of the diesel and the general direction most here are headed. Seems like most want the mondo HP from idle to redline, with virtually no dip in between.

 

[SteveH]

Very well phrased slybones.

 

[Missouri Mule]

swamp donkey,

One thing that determines torgue is the lenght of the connecting rod (known as stroke). The longer stroke the more torgue.

You want less torque go to a shorter stroke ( shorter connecting rod). I know you don't want to do that!

You could retard your timming to reduce torque. Not that either!

But I believe that increasing fuel to cylinders creates more power(horse power) but also creates more torgue along with it.

I think you could increase horse power and not increase torque by not increasing fuel.

You should be able to open up exhaust which should increase HP but not torque. (less restricted exhaust system)



torque x rpm/5252 =horsepower as slang stated.



I'm going to try to find the torque equation.



I believe that the 12v and 24v have different strokes. I try to check that out too.

 

[Joe G.]

MM,



I would be very surprised if the 12V and 24V had different strokes. The displacement is the same so if the stroke was changed then the bore would also have to be changed to keep the same displacement.

 

[Strick-9]

Swamp Donkey,



I wasn't going to comment on this thread, but after reading all the above replies, I feel a little sorry for you. You are challenging the mainstream of ideas here, and you are not alone in your quest. I've been hard at work for several months to get what I call a linear power curve.



There are ways to limit that auto shredding torque while still keeping plenty of horsepower. The camplate profile and the spring packs in your governor are the secrets.



Here's another hidden secret: Not all governor spring kits are the same!



Governor spring kits of old caused a huge surge of power right off idle with very little throttle. This was great for selling spring kits because it was a very dramatic difference before to after. BUT, your engine would produce 80-90% of its full power with 1/2" of throttle travel. The TV circuit in your transmission controls line pressure and is positioned by throttle travel. With the spring kit and a bombed motor, the engine produces nearly all its torque while the transmission is performing soft, low RPM shifts. This leads to excessive clutch slippage.



For the people throwing numbers around, let's try this.



If your transmission can live under 750 ft-lbs of torque then why don't you carry that same torque level from 1600rpms all the way to 3000 rpms where you will be putting out 428hp!



There are vendors still doing research on governor spring kits.

A good vendor doesn't stop improving a product just because it sells.



I appreciate it when someone challenges the mainstream. It forces vendors to continually improve our products and helps everyone.



-Chris

 

[Missouri Mule]

Your probably right Joe.

I was actually thinking the difference in torque and the same horse power between my Dodge 12v and Freightliner 24v.

Dodge 440 tq@ 1600 HP 215 @ 2600

Freight 520 tq@ 1600 HP 215 @ 2500

Also could get the Freight with 215/650 engine.



I'll check out the bore and stroke on each them Saturday or Sunday.



I think that like cams, different configurations of crankshafts can be used to get desired results. I known quite a few hot rodders (power freaks) but have not kept up with them.



Checked out specs in Dodge and Freightliner they were the same for bore and stroke. Injector pump different naturally, turbo I think is different ans exhaust system definitely different( freight no cat, bigger exhaust pipe?).

 

[Swamp Donkey]

Thanks Strick-9,

I was begining to think I was crazy... ... . but common sence tells me it can be done to a certain extent, and it is pretty obvious by the post above by MM that there are ways of doing it, along with your post of course. I will see what else becomes of the thread.

 

[Joe G.]

MM,



I'll bet the difference is in the fueling allowed at different RPM. The governor may be getting into the act too and defueling sooner for the FL. As mentioned above a flatter torque curve would result in higher HP. I expect that the faster the engine turns the more power is used to just turn the engine so a linear torque curve may not be possible. Improvement would certainly be nice. I'll leave that discussion to the experts.

 

[Eric_77]

Okay connecting rod DOES NOT equal stroke. Connecting rod must be longer than stroke but has nothing to do with what the stroke is. The conecting rod length relates to where in the cylinder the piston rides. For the same deck heght a longer rod will result in more compression and piston coming closer to head. You can also use a long rod when you "destroke" (make a shorter stroke) a motor so piston squish is the same or a short rod when you "stroke" (make a longer stroke) to the motor.



In general terms you would use a short rod motor to produce more torque and long rod motor to produce more hp. But that is for same bore stroke the shorter connecting rod will have a greater angle of thrust on the crank and thus produce more torque the long rod has less angle and thus can be turned at higher RPM.

 

[Missouri Mule]

This is the only thing I found in the TDR about torgue, I should say in the publications I have. Several older publications have more on Torque. I 'll have to research thru other auto motive books.



This is from pub. 15 page 51 Technical topics last paragraph( the author was comparing torque between gas and diesel engines).



"The other factor that produces more torque is the length of the rod. An example of this is when you use ratchet to loosen a nut. If you hold the ratchet near the handle it's very difficult,but if you hold the ratchet at the end of the handle, it's very easy.

The longer the connecting rod the more force (torque) can be applied to the crankshaft. ... . " Dave Allemon Eclectronic Diagnostic Developer, DC.



Dave shows comparison between the different strokes of the 5. 9 diesel engine=4. 72 and 5. 9 HD gas= 3. 58. I think we all know which one has more toque.

Interesting enough the bore for the 3. 59 HD gas is slightly less than the B3. 59



Need to go and research some more.