BertP
Edmonton, Alberta, Canada
Senior Member
Joined: 11/07/2003
View Profile
|
Joe - That's OK. I didn't really expect you to provide any data to support your position, but I thought I'd try.
On your Cat C15 vs the V10 in the SRT-10, I was unable to find out what rpm the V10 developed its max HP. It's not really that critical, so let's just assume it is at 5400 rpm, OK?
According to this site, the Cat makes its max torque at 1200 rpm and it stays flat up to 1500 rpm and then drops up to 2200 rpm with max HP ocurring at 1800 rpm. In that article, they talk about the Cat developing 625 HP, but to make our comparison with the V10 a little easier, let's assume that it develops 500 HP at 1800 rpm. That works out to about 1459 lb ft of torque at that rpm. The V10 develops 500 HP at 5400 rpm which works out to about 486 lb ft at that rpm. Looks kinda bad for the V10, doesn't it? But, the tranny of our big rig expects max HP at 1800 rpm, so we will bolt an under drive unit to the V10 with a 3:1 ratio. That means that the output of our power pack (the V10 plus the reduction gear) is 500 HP and 486 * 3 or 1458 lb ft of torque at 1800 rpm. The Cat and the V10 power pack have exactly the same HP and torque output. No magic here, Joe, just plain old physics.
topless - I understand what you are saying. It certainly is easier to boost the output of a diesel than it is to boost the output of a gasser. My only concern - and this is not limited to diesels by any strech of the imagination- is what you are doing to the engine. If you take an engine that is rated at 300 HP from the factory and boost that to 400, 500 or even 600 HP, you are putting an awful lot of strain on that engine and it will reduce the life expectancy of the engine. In some ways, it is more critical now than it used to be. Back in the 60's and 70's, we knew that the engine we were trying to soup up would not withstand the increased power if we were to leave the innerds stock. We at least replaced the conn rods and pistons, but more often than not we were looking at new cranks, heads and head bolts. Sometimes we even added gussets to the inside of the block to stiffen it up a bit. But with the diesels today, you just add a chip. Everything else is stock. That's scary.
Bert
|
PSDExcursion
Millstone NJ
Senior Member
Joined: 08/17/2001
View Profile
 Offline
|
Quote:Joe - That's OK. I didn't really expect you to provide any data to support your position, but I thought I'd try.
On your Cat C15 vs the V10 in the SRT-10, I was unable to find out what rpm the V10 developed its max HP. It's not really that critical, so let's just assume it is at 5400 rpm, OK?
According to this site, the Cat makes its max torque at 1200 rpm and it stays flat up to 1500 rpm and then drops up to 2200 rpm with max HP ocurring at 1800 rpm. In that article, they talk about the Cat developing 625 HP, but to make our comparison with the V10 a little easier, let's assume that it develops 500 HP at 1800 rpm. That works out to about 1459 lb ft of torque at that rpm. The V10 develops 500 HP at 5400 rpm which works out to about 486 lb ft at that rpm. Looks kinda bad for the V10, doesn't it? But, the tranny of our big rig expects max HP at 1800 rpm, so we will bolt an under drive unit to the V10 with a 3:1 ratio. That means that the output of our power pack (the V10 plus the reduction gear) is 500 HP and 486 * 3 or 1458 lb ft of torque at 1800 rpm. The Cat and the V10 power pack have exactly the same HP and torque output. No magic here, Joe, just plain old physics
Bert, screw your data, there is no friggin way in the real world the engine in a 1/2 ton pickup is going to do the same thing as a C15 500HP Cat diesel with 2050 ft lb tq pulling 80,000 lbs up a grade on I-70 west of Denver at over 8,000 ft elevation. There is a reason why no trucking company on the planet would even dream of putting in a gas engine with 25% of the torque of a diesel in a HD truck. Look at any tow rating chart from Dodge,GM or Ford and all diesels with the same or less HP than a gasser will have the highest tow ratings. Why would Ford rate a 255HP gasser at 13,000 lbs GCWR and a 235HP diesel at 20,000 lbs ? With your fuzzy math the 255HP gasser should have a higher rating than the diesel but it is rated 7,000 lbs less. I think you just like to yank my chain.
2002 Chevy Express 3500 8.1 155" WB passenger van
41 Ft 2003 Thor Citation 41-ZBSR TT w/ Hensley Arrow
|
All4fun
Calgary, Alberta
Full Member
Joined: 11/12/2002
View Profile
Offline
|
The gasser would have to be run at 5500 RPM almost everywhere if it were towing 80,000lbs, how long do you think an engine would last driving everywhere at 5500RPM and what kind of mileage do you think they'd get? I think the gasser would be much harder to drive as well, if you fell off the peak HP RPM, you would have a struggle to get it back up there without the monster torque, you would have to have a very closely geared gear box. The diesel on the other hand with it's massive torque would be better able to climb back up to it's peak HP RPM but once they are both there they should be equally capable.
My analogy for HP and Torque is the difference between sticking your finger in vise and closing it and having you finger pinched against a wall by a baseball at 60MPH. Both have equal force and will really hurt but one is because of speed, the other is just sheer force but the end result is the same.
An interesting comparison would be an F1 type race engine that develops over 1200 HP but only has 200 ftlbs of torque (or something like that, I know it's not much) If they had it geared so it could harness it's max HP at 17,000 RPM it would out pull the diesel but try and even get one of these cars moving when it's not at it's peak HP RPM.
My two bits.
JD
'07 GMC Sierra 2500HD CC SLT 4x4 Duramax
'05 24FB Thor Fury
|
PSDExcursion
Millstone NJ
Senior Member
Joined: 08/17/2001
View Profile
Offline
|
Quote:An interesting comparison would be an F1 type race engine that develops over 1200 HP but only has 200 ftlbs of torque (or something like that, I know it's not much) If they had it geared so it could harness it's max HP at 17,000 RPM it would out pull the diesel but try and even get one of these cars moving when it's not at it's peak HP RPM.
I am sure a 1200HP F1 engine would not out pull a 1000HP diesel like in the Cat 777D dump truck that weighs 360,000 lbs loaded and has 3476 lb ft tq.
![[image]](http://cmms.cat.com/cmms/servlet/cat.dcs.cmms.servlet.ImageServlet?imageid=C046094&imageType=2)
|
BertP
Edmonton, Alberta, Canada
Senior Member
Joined: 11/07/2003
View Profile
|
Quote:The gasser would have to be run at 5500 RPM almost everywhere if it were towing 80,000lbs, how long do you think an engine would last driving everywhere at 5500RPM and what kind of mileage do you think they'd get?
Whether that is true or not (it is) isn't the issue. Joe said that the gasser could not perform the same as the diesel pulling 80,000 up a hill and I showed how it could. Even if the V10 was completely worn out and had to be replaced by the time the truck got to the top isn't the issue here.
Quote:I think the gasser would be much harder to drive as well, if you fell off the peak HP RPM, you would have a struggle to get it back up there without the monster torque, you would have to have a very closely geared gear box. The diesel on the other hand with it's massive torque would be better able to climb back up to it's peak HP RPM but once they are both there they should be equally capable.
I am inclined to disagree with you here. Most big diesels (the Cat C15 included) have a fairly narrow operating rpm range. In the case of the Cat, it is from around 1000 ro 2200 rom. That's only a 1200 rpm spread. The V10 OTOH can operate from around 1000 to 6000 (this is a guess) rpm. That is a 5000 rpm spread. So, it would seem to me that, if the V10 has a fairly flat torque cruve, it would beable to re attain its max HP point easier than the Cat.
Quote:My analogy for HP and Torque is the difference between sticking your finger in vise and closing it and having you finger pinched against a wall by a baseball at 60MPH. Both have equal force and will really hurt but one is because of speed, the other is just sheer force but the end result is the same.
Pretty good analogy, I'd say.
Quote:An interesting comparison would be an F1 type race engine that develops over 1200 HP but only has 200 ftlbs of torque (or something like that, I know it's not much) If they had it geared so it could harness it's max HP at 17,000 RPM it would out pull the diesel but try and even get one of these cars moving when it's not at it's peak HP RPM.
My two bits.
The torque of the F1 can be calculated. If the 1200 HP is generated at 10,000 rpm (I think that's fairly accurate), then Torque = 1200 * 5252 / 10,000 = 630 lb ft. I don't know what the torque curve looks like on that engine, but as long as it is not too peaky, it should get the load moving just fine as long as it has the correct gearing, just like the V10 above.
Bert
* This post was
last
edited 08/15/04 12:37pm by BertP *
View edit history
|
|
|
BertP
Edmonton, Alberta, Canada
Senior Member
Joined: 11/07/2003
View Profile
|
Quote:Bert, screw your data, there is no friggin way in the real world the engine in a 1/2 ton pickup is going to do the same thing as a C15 500HP Cat diesel with 2050 ft lb tq pulling 80,000 lbs up a grade on I-70 west of Denver at over 8,000 ft elevation. There is a reason why no trucking company on the planet would even dream of putting in a gas engine with 25% of the torque of a diesel in a HD truck. Look at any tow rating chart from Dodge,GM or Ford and all diesels with the same or less HP than a gasser will have the highest tow ratings. Why would Ford rate a 255HP gasser at 13,000 lbs GCWR and a 235HP diesel at 20,000 lbs ? With your fuzzy math the 255HP gasser should have a higher rating than the diesel but it is rated 7,000 lbs less. I think you just like to yank my chain.
No, I am not trying to jerk your chain. Others have shown how two engines with dramatically different troque characteristics can behave exactly the same if given the proper gearing. That's all I have done. Try to look at it from the tranny's perspective. Will it be able to detect when the V10 is providing the power vs when the Cat is up there? No, it will not because it will see exactly the same amount of HP and torque regardless of which engine is there.
As far as what kind of engine you will find in the big rigs, how many of the people who actually buy these truck (usually the bean counters) have ever heard of torque? If they come across the word in a report, most of them will probably think the report was written by some bonehead who doesn't know how to use a spell checker and he was actually referring to one of those wollen hats truckers wear in the winter. What they are interested in is a) How much does it cost to buy this engine? b) How much does it cost to operate this engine? and c) How much does it cost to maintain this engine? That's it. The engine that costs the least wins.
Consider: You and I have competing transport companies doing exactly the same work. Your trucks, fully loaded, will get around 4 mpg on the highway. Mine, fully loaded with the same size load, will get around 10 mpg. If everything else is the same, who do you think will stay in business longer? You won't be able to compete with me because your fuel bills will be twice mine. It all comes down to $'s
We have already addresses, many times, that there is more to determining the GCVW of a vehicle than just HP and/or torque.
Bert
|
BertP
Edmonton, Alberta, Canada
Senior Member
Joined: 11/07/2003
View Profile
|
Quote:I am sure a 1200HP F1 engine would not out pull a 1000HP diesel like in the Cat 777D dump truck that weighs 360,000 lbs loaded and has 3476 lb ft tq.
Yes, it would, if it is geared properly. The truck would probably require an engine change at every fuel up, but it would out pull the diesel without a problem.
Bert
|
PSDExcursion
Millstone NJ
Senior Member
Joined: 08/17/2001
View Profile
Offline
|
Quote:Quote:I am sure a 1200HP F1 engine would not out pull a 1000HP diesel like in the Cat 777D dump truck that weighs 360,000 lbs loaded and has 3476 lb ft tq.
Yes, it would, if it is geared properly. The truck would probably require an engine change at every fuel up, but it would out pull the diesel without a problem.
Bert
Maybe I could get one of John Force's engines and put it in a locomotive to pull a 250 car train over the Rockies.![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/rolleyes.gif "rolleyes")
|
BertP
Edmonton, Alberta, Canada
Senior Member
Joined: 11/07/2003
View Profile
|
Quote:Maybe I could get one of John Force's engines and put it in a locomotive to pull a 250 car train over the Rockies.
I see you have resorted to sarcasm again. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/frown.gif "frown")
Joe, the truth of the matter is that, if you could get Mr. Force's engines to last long enough (as designed, they will last a matter of seconds between rebuilds. You don't need longevity when drag racing), then, yes, those engines would work just fine. The diesels in most of the locomotives are 3000 HP and Mr. Force's engines are, last time I checked, around 3500 HP.
Bert
|
wkdelsol
sun city,ca. usa
New Member
Joined: 06/29/2004
View Profile
|
PSDExcursion
I guess your reply means you idel for a half hour befor pulling out of the camp ground??????.
|
|
|
|
