Lost some ponies on the dyno...
06-04-2007, 11:01 AM
#16
Rennlist Member
Since your HP & torque match, but your AF ratios do not, I would suspect that the issue is related to temperature or gas quality. What was the temp difference between the two runs?
I am not going to ask what kind of gas you got, because even if you filled up at the same station, there is no chance in hell that the gas is anywhere near the same as it was 1 or 2 years ago.
I am not going to ask what kind of gas you got, because even if you filled up at the same station, there is no chance in hell that the gas is anywhere near the same as it was 1 or 2 years ago.
06-04-2007, 12:11 PM
#17
Legacy Flounder
Rennlist Member
Rennlist Member
Thread Starter
Join Date: Nov 2004
Location: Cumberland, RI
Posts: 3,439
Likes: 0
Received 0 Likes
on
0 Posts
EXCELLENT Point Murph, DUH! I just proved this out on the minivan coming back from Florida (Smacks head!).
11/04 & 6/05 were before the Ethanol changeover here in New England. We're now running 10% Ethanol. Last year I got about 27mpg on the highway with the van, now I'm getting 24mpg or so. I knew Ethanol-added gasoline had less energy than MTBE-added, I even posted about it when it happened around April '06. (Smacks head again!)
Thanks for the feedback guys. Makes much more sense now. Damn, now I need to re-test with all the mufflers again to get accurate comparisons again.
11/04 & 6/05 were before the Ethanol changeover here in New England. We're now running 10% Ethanol. Last year I got about 27mpg on the highway with the van, now I'm getting 24mpg or so. I knew Ethanol-added gasoline had less energy than MTBE-added, I even posted about it when it happened around April '06. (Smacks head again!)
Thanks for the feedback guys. Makes much more sense now. Damn, now I need to re-test with all the mufflers again to get accurate comparisons again.
06-04-2007, 05:00 PM
#18
Rennlist Member
Originally Posted by 84_Carrera
EXCELLENT Point Murph, DUH! I just proved this out on the minivan coming back from Florida (Smacks head!).
11/04 & 6/05 were before the Ethanol changeover here in New England. We're now running 10% Ethanol. Last year I got about 27mpg on the highway with the van, now I'm getting 24mpg or so. I knew Ethanol-added gasoline had less energy than MTBE-added, I even posted about it when it happened around April '06. (Smacks head again!)
Thanks for the feedback guys. Makes much more sense now. Damn, now I need to re-test with all the mufflers again to get accurate comparisons again.
11/04 & 6/05 were before the Ethanol changeover here in New England. We're now running 10% Ethanol. Last year I got about 27mpg on the highway with the van, now I'm getting 24mpg or so. I knew Ethanol-added gasoline had less energy than MTBE-added, I even posted about it when it happened around April '06. (Smacks head again!)
Thanks for the feedback guys. Makes much more sense now. Damn, now I need to re-test with all the mufflers again to get accurate comparisons again.
06-04-2007, 08:00 PM
#20
Legacy Flounder
Rennlist Member
Rennlist Member
Thread Starter
Join Date: Nov 2004
Location: Cumberland, RI
Posts: 3,439
Likes: 0
Received 0 Likes
on
0 Posts
Jeremy -
When I read your post (and I did read it, btw), I was thinking water in gas, cheapo brand, etc.
When I read Murph's, he mentioned, "there is no chance in hell that the gas is anywhere near the same as it was 1 or 2 years ago." - this just triggered the "what's different about gas now vs. 2 years ago" thought in my head, which instantaneously screamed "CORN!".
I do appreciate everyone's input - thanks to all!
When I read your post (and I did read it, btw), I was thinking water in gas, cheapo brand, etc.
When I read Murph's, he mentioned, "there is no chance in hell that the gas is anywhere near the same as it was 1 or 2 years ago." - this just triggered the "what's different about gas now vs. 2 years ago" thought in my head, which instantaneously screamed "CORN!".
I do appreciate everyone's input - thanks to all!
06-04-2007, 10:11 PM
#21
Drifting
No problem Fred - just busting your chops/// But really for dyno's unless they are back to back - the end number can be pretty misleading.
I am a little concerned about all this ethanol though.
I am a little concerned about all this ethanol though.
06-04-2007, 11:08 PM
#22
Legacy Flounder
Rennlist Member
Rennlist Member
Thread Starter
Join Date: Nov 2004
Location: Cumberland, RI
Posts: 3,439
Likes: 0
Received 0 Likes
on
0 Posts
Well while I was waiting in the walk-in tonight (yay, I have strep, but no ear infection despite the pain), I read an article on the Ethanol / BioDiesel / other alternative fuels in the pipeline. The article quoted as much as 30% lower energy for Ethanol vs. traditional Gasoline. I would imagine this is E85 they're referring to, NOT 10% Ethanol gas.
So, if 10% of my fuel is Ethanol, and it has 30% less energy than the gas it's added to, that'd be a 3% drop in power? Assuming 15% driveline losses consistent between the runs, the 203.5hp pull would be about 240hp at the wheels. A 3% loss in crank hp would lower me to... 232.8 crank hp, then 85% of that is 197.8 - right where my runs were. Of course this is all BS falling out of my butt, however it seems to make some kind of sense to me.
Anyway, I think I'll sleep a little better now.
So, if 10% of my fuel is Ethanol, and it has 30% less energy than the gas it's added to, that'd be a 3% drop in power? Assuming 15% driveline losses consistent between the runs, the 203.5hp pull would be about 240hp at the wheels. A 3% loss in crank hp would lower me to... 232.8 crank hp, then 85% of that is 197.8 - right where my runs were. Of course this is all BS falling out of my butt, however it seems to make some kind of sense to me.
Anyway, I think I'll sleep a little better now.