Forum Discussion
158 Replies
Huntindog wrote:
4x4ord wrote:
I kind of doubt the GMs fan ran all the time.
^^^ Its really hard to say. Maybe GM is wanting cooler temps so the cooling fan never shut off. My Ford runs up to 205 *F in minus 5*F weather cruising down the level highway without a trailer. The GM ran in its peak hp range the whole way up the hill and yet put less power to the pavement than the Ford did running at 2200 rpm. If that big cooling fan was running continuous it may have robbed an awful lot of HP.
In the Ford, when it came on, it was VERY loud.
The GM was quiet inside.
And if that huge fan had been running, it should have made some noise, and I would think that they would have talked about it like they did with the Ford.
The low trans temp doesn't suprise me, as my 2011 also runs cool even towing in AZ in the summer.
In my experience, Ford fans have always been loud.- From what I have read and what I have scene in past reviews, the L5P Duramax normally runs at 210F coolant temps even unloaded which is where it was at in the video the whole way up. I zoomed in on the second gauge from the left which is coolant temp. The Cummins fan kicks on at 219F so if it kicks on when they do that run then you know it at least got as hot as the PSD. Although, since the coolant does not cool down hot air coming from the turbocharger and going into your engine, it would not have any effect on EGT's.
- ^^^ I think if the fan on the GM was cutting in and out we would have heard it. I kind of think it was either always on or always off. The thing that is hard for me to understand is this: The Ford is supposed to make 1050 lbft of torque at 1600 rpm which is 320 hp. It is rated at 475 hp at 2800 rpm. The power very likely builds quite uniformly over the power band which means it likely gains about 13 hp per 100 rpm. This means the Ford should be capable of making around 398 hp at the 2200 rpm it ran at.
The GM is supposed to make 445 hp at 2800 and 279 hp at 1600. Therefore the Duramax builds about 14 HP per 100 engine rpm. If we say the Duramax ran at about 2600 rpm it should have been able to generate about 420 hp at that rpm. The time difference up the mountain between the two trucks indicates the Ford was putting out about 63 more hp than was the Duramax. If the Ford was making 398 HP the Duramax was only making 335 ..... yet it should have been capable of making 420. 4x4ord wrote:
I kind of doubt the GMs fan ran all the time.
^^^ Its really hard to say. Maybe GM is wanting cooler temps so the cooling fan never shut off. My Ford runs up to 205 *F in minus 5*F weather cruising down the level highway without a trailer. The GM ran in its peak hp range the whole way up the hill and yet put less power to the pavement than the Ford did running at 2200 rpm. If that big cooling fan was running continuous it may have robbed an awful lot of HP.
In the Ford, when it came on, it was VERY loud.
The GM was quiet inside.
And if that huge fan had been running, it should have made some noise, and I would think that they would have talked about it like they did with the Ford.
The low trans temp doesn't suprise me, as my 2011 also runs cool even towing in AZ in the summer.- ^^^ Its really hard to say. Maybe GM is wanting cooler temps so the cooling fan never shut off. My Ford runs up to 205 *F in minus 5*F weather cruising down the level highway without a trailer. The GM ran in its peak hp range the whole way up the hill and yet put less power to the pavement than the Ford did running at 2200 rpm. If that big cooling fan was running continuous it may have robbed an awful lot of HP.
- I just watched the behind the scenes footage, which I thougt was more informative than the original release.
Some things stood out:
It was colder than I thought at 25 degrees.
And at those temps, the Ford was working to maintain safe operating temps. The cooling fan ran a lot. Yet the coolant was said to be 219, and the trans 220.
By contrast the GMs trans was 185.I did not catch what the coolant was, but I never heard the fan come on.
My takeaway is that the Ford will NOT dominate in hot temps. Cummins12V98 wrote:
Thanks for the reply!
Just looked at a video I did right after getting current 15 DRW and 16 DRV heading South I-5 coming up the last 4 miles to Ashland pass. The RV and truck were I would guess 32,500# or so. The whole time I was in 4th at 49-51mph. In that situation I bet a gear in-between 3 n 4 may have made a couple mile per our difference. Not sure what RPM I was going but it sounded like it was not very high.
It was probably running about 2150 rpm in 4th. Even if downshifting at 50 mph into third with the Aisin would have put you at an rpm where the Cummins makes more power it wouldn't provide any gain in speed because the engine would be revving some where around 2900 rpm which is already beyond the rpm of its peak power level. The other thing with the Cummins is that at 2800 rpm it makes 400 HP and at 1800 rpm it makes 343 HP, so it's likely making about 367 HP at 2150 rpm. If it had a gear half way between 3rd and 4th, the engine would run at 2475 rpm in that new gear. 2475 rpm might gain you about 16 additional HP. 16 more ponies isn't really going to buy you a whole lot of speed anyway ... probably would be about 2 mph.
Edit : Oops I was thinking about the 2019 Cummins. Your 2015 would gain quite a bit with an in between gear .... probably 6 or 7 mph.- Thanks for the reply!
Just looked at a video I did right after getting current 15 DRW and 16 DRV heading South I-5 coming up the last 4 miles to Ashland pass. The RV and truck were I would guess 32,500# or so. The whole time I was in 4th at 49-51mph. In that situation I bet a gear in-between 3 n 4 may have made a couple mile per our difference. Not sure what RPM I was going but it sounded like it was not very high. Cummins12V98 wrote:
4X, how much do you think these 10 speeds help with the Diesel engines compared to their previous 6 speeds? Lets say the Ford with todays HP/TQ with 6 speed would it do as well as the 10 speed or???
On this last Ike run the Ford's 10 speed did nothing for it. The truck ran at 2200 rpm. Had it downshifted it would have jumped to 2600 where it would have had an additional 52 HP. That additional power would have allowed it to accelerate up to over 2800 rpm where the power starts dropping off again. So down shifting could have brought the rpm to 2600. Then, even had it accelerated to only 2800 rpm, it would have taken about 20 seconds off the time up the mountain. The Ram with the Aisin transmission should have enough powe to pull the hill in 3rd gear. 3rd gear at 42 - 48 mph will have the engine revving between 24500 and 2800 rpm .... so that should be pretty ideal. The 6R140 with a 4.10 rear end could have been in 3rd gear running at 2540 and accelerating instead of 2200 rpm in 5th with the 10 speed/3.55 gears. Then on the lower less steep part of the grade the 6r140/4.10 could have been running at 2268 rpm in 4th instead of 2200 in 6th with the 10 speed.
So like I said the 10 speed in manual mode could have been an asset but in drive it was a disadvantage over a properly shifted 6 speed.
Edit: Although the above is all true, I am not going to be racing anyone up a mountain so I like the idea of the Ford running at a lower rpm even though it takes a little longer up the hill. If I really felt the need to get to the top of the hill as fast as possible I wouldn't mind manually shifting.Cummins12V98 wrote:
mich800 wrote:
Cummins12V98 wrote:
4X, how much do you think these 10 speeds help with the Diesel engines compared to their previous 6 speeds? Lets say the Ford with todays HP/TQ with 6 speed would it do as well as the 10 speed or???
It will do better in a variety of situations compared to the previous version. This does not equal better in any one or every specific test.
If you focus on one test as a proxy for usefulness you are missing the bigger picture of technological advancements.
I agree, I was curious his opinion on that specific situation.
I guess my thinking is how much of the time are we using all these gears, do they make much of a difference?
Cruising down the highway in high gear 6 or 10 speeds any difference?
Pulling a 6% grade for 5 miles make much difference? Once you are in your gear at a given grade that does not change.
To me the fact we have/had 6 equally spaced gears was the most improvement we all have seen. Now "I" think most of it is advertising and not that much is to be gained.
I think where the 10 speed will benefit is more steady stuff and lower throttle accelerations where it does not have to make big gear jumps. I am thinking any test that involves pedal to the floor HP shootouts will probable be fairly competitive to any other transmissions unless you seek out a hill that just suits a particular trucks relative strength.
