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Old 02-01-2014, 02:47 PM
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Big HP but what about TQ?

I'm curious to know what combinations have been tried to produce big torque numbers. I see a lot of people posting about running 175s, 190s, non VGTs, Stage 4s, etc... These combinations are usually accompanied by HP numbers, but very rarely TQ numbers. For you guys making 500-800 HP what are your torque numbers? Also can certain parts be selected differently to achieve a higher torque number than horsepower, for example bigger injectors but a moderate sized turbo. That was just an example for better clarification of what I was trying to ask. I know that horsepower is derived from torque, but I've seen guys on here with horsepower numbers in the 600s and torque in the 900s. In my mind it seems there might have been something's done differently to achieve a higher torque number at the cost of some of that horsepower. All input is appreciated.
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Old 02-01-2014, 03:13 PM
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Generally speaking, for a diesel, tq is twice the hp.
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Old 02-01-2014, 03:32 PM
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Originally Posted by powerstrokeshellback View Post
Generally speaking, for a diesel, tq is twice the hp.
That was my impression too, but it's not holding true with the few big HP numbers I've seen that did include torque numbers. For example:

Adrian: 769 hp and 1299 ft/lbs
Oliver: 618 hp and 978 ft/lbs
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Old 02-01-2014, 03:38 PM
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Originally Posted by 6literdiesel View Post
That was my impression too, but it's not holding true with the few big HP numbers I've seen that did include torque numbers. For example:

Adrian: 769 hp and 1299 ft/lbs
Oliver: 618 hp and 978 ft/lbs
IMO I think you lose some tq when you go up on nozzle size because the fuel doesn't atomize as well.
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Old 02-01-2014, 04:42 PM
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I want to point out a few things before I explain my theories on tq numbers. This is also going to bring up many of the reasons that peak hp and peak tq numbers should not be used to compare 2 different numbers from 2 different trucks run on different dynos at different times. Also why dyno numbers should not be used to promote or sell products. When used correctly dynos are better off used to measure changes made to a certain setup on a truck.

Something that affects peak tq will be how the dynos are run and work. I know I run my truck on a dyno very similar to oliver/odawg. All you do to dyno the truck is stick the truck in Drive, get to a certain gear (usually OD), and then roll into the pedal without letting the truck downshift. If you just floor it then sometimes it downshifts and that dyno run wont count. This is a very accurate representation of what kind of true torque you are making when driving your truck. But this usually produces a lower peak tq number measurement because you are starting your dyno run at like 1800rpms and don't reach max boost til 2500-2900 rpms. Also the load is lighter. The other factor is that you cannot load up the dyno to put more load on the engine to produce more boost ealier in the rpms range.

Here is a picture of a dyno run that was done on a roller dyno like Oliver and I. You can see how late the dyno starts (2000rpms) because that is actually how we drive our trucks on the rollers.


Another type of dyno is an inertia/mustag dyno like the one that adrian ran. This is different because you can get the truck in Direct drive (5th gear, not OD) and actually lock it in that gear. Then you can floor it from a very low speed and not worry about the truck downshifting. Also you can apply a huge load to the truck also to help produces more boost earlier. All this will equal out to showing a huge tq number that is not possible during any actual driving experience.

Here is a picture of adrians dyno. You can actually see that the truck was locked in gear for a long while before the turbo even starts to spool or create power. This is because he is able to start the dyno run so early and mash the pedal to the floor without having to worry about the truck downshifing.


Not bashing or saying that anyones number are incorrect... just pointing out the different ways that dynos are run.



Now to answer your questions more directly.

You do lose a little bit of tq if you go too big on nozzles because of less atomization. The difference between larger and smaller nozzles would be like pouring a cup of water on a fire vs spraying a huge fine mist on a fire. The fine mist will burn hotter, quicker, and more efficiently.


Something to note is that in some cases you will lose tq and gain hp with certain setups. Oliver/Odawg saw this when he switched from his billet pmax to his barder stage 3. That is because the smaller turbos spool faster and operate more efficiently earlier in the rpms. You need bigger turbos to produce more air but a bigger turbo will usually push your peak torque number farther in the rpm range. There is nothing wrong with this but it does happen. Now if you run on a mustag dyno and lock the truck into gear like Adrian than you are still able to measure that peak tq area even though you would never achieve that scenario while driving.

Here is a dyno graph showing a truck with bigger injectors running a stock turbo vs a stage 3 turbo. You can see that the stage 3 makes tons more hp and only a little more tq. You can also see that the torque curved moves to the right because a smaller turbo (especially with the 13 blade turbine) will operate more efficiently and spool up faster at lower rpms. With the change of a turbo the truck gain about 30tq and 130hp. You can also see what I mean by the dyno starting at about 2000rpms... if you were to run this truck on a mustang dyno then it would have produces a much higher tq number with the bigger turbo... but that bigger tq number would not be realistic for any possible driving scenario. Also something else you can see is that even though the peak tq is only 30tq higher, once the smaller turbo gets out of its efficiency range and the bigger turbo starts producing way more air you can see that there is about a 200tq increase throughout the rest of the rpm band. The hp and tq from the smaller turbo drops like a rock after about 2500rpms while the bigger turbo has a flatter tq curve and continues to make hp all the way to the end of the rpm band.




Under actual driving condition without locking your truck in gear for the dyno run... Huge injectors with great ICP and a smaller to mid sized vgt turbo will produce the most torque. Compounds would theoretically produce really good tq depending on how small the high pressure charger is... but I have not been able to test that theory yet.

Last edited by peixinho; 02-01-2014 at 06:03 PM.
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Old 02-01-2014, 04:44 PM
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Also I forgot to add that IMO having a good healthy flat torque curve is much more advantageous than having a monster peak tq that dies off quickly.
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Old 02-01-2014, 06:36 PM
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Quote:
Originally Posted by peixinho View Post
I want to point out a few things before I explain my theories on tq numbers. This is also going to bring up many of the reasons that peak hp and peak tq numbers should not be used to compare 2 different numbers from 2 different trucks run on different dynos at different times. Also why dyno numbers should not be used to promote or sell products. When used correctly dynos are better off used to measure changes made to a certain setup on a truck.

Something that affects peak tq will be how the dynos are run and work. I know I run my truck on a dyno very similar to oliver/odawg. All you do to dyno the truck is stick the truck in Drive, get to a certain gear (usually OD), and then roll into the pedal without letting the truck downshift. If you just floor it then sometimes it downshifts and that dyno run wont count. This is a very accurate representation of what kind of true torque you are making when driving your truck. But this usually produces a lower peak tq number measurement because you are starting your dyno run at like 1800rpms and don't reach max boost til 2500-2900 rpms. Also the load is lighter. The other factor is that you cannot load up the dyno to put more load on the engine to produce more boost ealier in the rpms range.

Here is a picture of a dyno run that was done on a roller dyno like Oliver and I. You can see how late the dyno starts (2000rpms) because that is actually how we drive our trucks on the rollers.


Another type of dyno is an inertia/mustag dyno like the one that adrian ran. This is different because you can get the truck in Direct drive (5th gear, not OD) and actually lock it in that gear. Then you can floor it from a very low speed and not worry about the truck downshifting. Also you can apply a huge load to the truck also to help produces more boost earlier. All this will equal out to showing a huge tq number that is not possible during any actual driving experience.

Here is a picture of adrians dyno. You can actually see that the truck was locked in gear for a long while before the turbo even starts to spool or create power. This is because he is able to start the dyno run so early and mash the pedal to the floor without having to worry about the truck downshifing.


Not bashing or saying that anyones number are incorrect... just pointing out the different ways that dynos are run.



Now to answer your questions more directly.

You do lose a little bit of tq if you go too big on nozzles because of less atomization. The difference between larger and smaller nozzles would be like pouring a cup of water on a fire vs spraying a huge fine mist on a fire. The fine mist will burn hotter, quicker, and more efficiently.


Something to note is that in some cases you will lose tq and gain hp with certain setups. Oliver/Odawg saw this when he switched from his billet pmax to his barder stage 3. That is because the smaller turbos spool faster and operate more efficiently earlier in the rpms. You need bigger turbos to produce more air but a bigger turbo will usually push your peak torque number farther in the rpm range. There is nothing wrong with this but it does happen. Now if you run on a mustag dyno and lock the truck into gear like Adrian than you are still able to measure that peak tq area even though you would never achieve that scenario while driving.

Here is a dyno graph showing a truck with bigger injectors running a stock turbo vs a stage 3 turbo. You can see that the stage 3 makes tons more hp and only a little more tq. You can also see that the torque curved moves to the right because a smaller turbo (especially with the 13 blade turbine) will operate more efficiently and spool up faster at lower rpms. With the change of a turbo the truck gain about 30tq and 130hp. You can also see what I mean by the dyno starting at about 2000rpms... if you were to run this truck on a mustang dyno then it would have produces a much higher tq number with the bigger turbo... but that bigger tq number would not be realistic for any possible driving scenario. Also something else you can see is that even though the peak tq is only 30tq higher, once the smaller turbo gets out of its efficiency range and the bigger turbo starts producing way more air you can see that there is about a 200tq increase throughout the rest of the rpm band. The hp and tq from the smaller turbo drops like a rock after about 2500rpms while the bigger turbo has a flatter tq curve and continues to make hp all the way to the end of the rpm band.




Under actual driving condition without locking your truck in gear for the dyno run... Huge injectors with great ICP and a smaller to mid sized vgt turbo will produce the most torque. Compounds would theoretically produce really good tq depending on how small the high pressure charger is... but I have not been able to test that theory yet.
Excellent post!!

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Old 02-01-2014, 07:32 PM
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Horsepower isn't a real measurement, it's simply a calculation derived from torque X rpm / 5252. Extending where you make peak torque higher into the rpm band increases hp even if you made the same torque (think about ricers making 500+ hp at 8,000rpm but very little torque). horsepower is a speed equation basically and torque is true power.
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Old 02-01-2014, 08:10 PM
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Good info for sure. That is always how I have understood the differences in dyno types and the dynos affects of a turbo on an engine. One thing to point out as well is that if a turbo is way oversized it will adversely affect torque down low to an even larger degree. This is simply due to the fact that it spool much later. It all comes down to what a person wants in their setup and where they want their boost at.

One thing I am curious about though is your comment about how a dyno starting at 2000rpm is more closely related to how we drive. What you said is more than true if say we were driving at highway speeds but there are also instances where a mustang dyno could hold true as well. One such instance would be entering a freeway after a stop or maybe even a slow roll race. IMO this would produce numbers more similar to that dyno type. What is your opinion on this? And again thank you for the informative post!
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Old 02-02-2014, 07:39 AM
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Originally Posted by 88 Ford View Post
Good info for sure. That is always how I have understood the differences in dyno types and the dynos affects of a turbo on an engine. One thing to point out as well is that if a turbo is way oversized it will adversely affect torque down low to an even larger degree. This is simply due to the fact that it spool much later. It all comes down to what a person wants in their setup and where they want their boost at.

One thing I am curious about though is your comment about how a dyno starting at 2000rpm is more closely related to how we drive. What you said is more than true if say we were driving at highway speeds but there are also instances where a mustang dyno could hold true as well. One such instance would be entering a freeway after a stop or maybe even a slow roll race. IMO this would produce numbers more similar to that dyno type. What is your opinion on this? And again thank you for the informative post!


I see exactly what you are saying and I will explain the two differences. Most of the time when we are driving our trucks you only see below 1500rpms for the first few seconds in 1st gear and the tq converter is not locked, and then you stay above 1500-2000rpms for the rest of the drive until you stop again. For 5th gear or OD would venture to say that most of us stay between 1600-1800 rpms. If you are at 1200rpms and floor it then 90% of the time your truck will downshift into a lower gear.


So on a typical roller dyno like dynojet. You simply get going and bring yourself up to whatever gear you want to run in. Then you roll into the throttle just like you would on the street. This is pretty realistic driving characteristic of what you would actually be doing on the street.


On a dyno like a mustang... you can put the truck in 5th gear, lock the tq converter, slow down to 600rpms, and then mash the pedal without worrying about downshifting at all. The only way I see this being an actual scenario is if you had a stick shift truck, stick the truck in whatever gear is direct drive (probably 4th or 5th) slow the truck down to about 20mph so it is lugging the motor like crazy at 600rpms and then floor the truck. It would smoke like crazy and be super slow for like 10 seconds and then when the turbo lights it would take off. Oh and if they are putting a big heavy load on the truck then it would be like doing this same test with a trailer behind the truck.




Once again not saying which is right or wrong... just explaining the differences and why some dynos read higher than others
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