can it be too cold to run the best?
Thread Starter
single digit dreamer
iTrader: (6)
Joined: Mar 2002
Posts: 9,757
Likes: 4
From: omaha ne
can it be too cold to run the best? check it out.
2 weeks ago it was 10deg, best i could run was 9psi before i started seeing knock and i actualy heard knock at 10psi once. with some good gas(98octane) i was able to turn it up to about 13psi before is showed KR.
today it is 50deg out, at 9psi i am running the same ET as before. i just turned it up to 13psi and still got no KR. this is on pump gas only. then to top it off i am running the same ET's at when it was 10deg. 50deg is what i might see on a good night at the track so i feel real good about the gtech numbers i am seeing.
best run of 10.91@128 on the gtech, add .3 for my std gtech corection and then drop about .3 for the extra 400lb's i had on board so that sugest i can pull some 10's on pump gas!!
so, is 10deg just too cold to run right? can it be that 50deg is better? is their an ideal temp?
2 weeks ago it was 10deg, best i could run was 9psi before i started seeing knock and i actualy heard knock at 10psi once. with some good gas(98octane) i was able to turn it up to about 13psi before is showed KR.
today it is 50deg out, at 9psi i am running the same ET as before. i just turned it up to 13psi and still got no KR. this is on pump gas only. then to top it off i am running the same ET's at when it was 10deg. 50deg is what i might see on a good night at the track so i feel real good about the gtech numbers i am seeing.
best run of 10.91@128 on the gtech, add .3 for my std gtech corection and then drop about .3 for the extra 400lb's i had on board so that sugest i can pull some 10's on pump gas!!
so, is 10deg just too cold to run right? can it be that 50deg is better? is their an ideal temp?
Thread Starter
single digit dreamer
iTrader: (6)
Joined: Mar 2002
Posts: 9,757
Likes: 4
From: omaha ne
Originally Posted by gator's 99TA
when it is so cold, the tires have just no chance to get soft.
my 60's are all similur. 1.75's or so, 4wd helps there.
TECH Enthusiast
Joined: Mar 2004
Posts: 697
Likes: 0
the way I understand it is that the colder air is, the denser it is. since boost is resistance to flow, 13 psi at 10* is actually more air than 13 psi at 50*. therefore, you dont need to run as high a boost level in really cold conditions to see the same results, someone educate me if Im wrong please...
Trending Topics
Thread Starter
single digit dreamer
iTrader: (6)
Joined: Mar 2002
Posts: 9,757
Likes: 4
From: omaha ne
yep, ~1.75's
about 1-2mph slower but the some everything else. i think by mid run(warm night) it is starting to fall of a hair on power compared to the cold night.
about 1-2mph slower but the some everything else. i think by mid run(warm night) it is starting to fall of a hair on power compared to the cold night.
Last edited by parish8; Jan 24, 2005 at 08:30 PM.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Thread Starter
single digit dreamer
iTrader: (6)
Joined: Mar 2002
Posts: 9,757
Likes: 4
From: omaha ne
Originally Posted by B18B1LS1
Once you started seeing KR did you tune it out and see what it ran with everything else the same?
You ever notice alot of people blowing there motor's when it starts to get cold out
In the colder weather you should back the timing down atleast 2-4 degree's.The car will make the same or more HP than it did in the hotter weather.I also like setting A/F to 11-1 for alittle safety.
Turbo cars for some reason are very touchy when the temp drops alot.I have to turn the boost on my GN from 19lbs down to 15lbs when the temp is under 50 degree's
In the colder weather you should back the timing down atleast 2-4 degree's.The car will make the same or more HP than it did in the hotter weather.I also like setting A/F to 11-1 for alittle safety.
Turbo cars for some reason are very touchy when the temp drops alot.I have to turn the boost on my GN from 19lbs down to 15lbs when the temp is under 50 degree's
Thread Starter
single digit dreamer
iTrader: (6)
Joined: Mar 2002
Posts: 9,757
Likes: 4
From: omaha ne
i am not complaining, actualy i am thrilled that it isn't slowing down form the days when it was real cold and infact is quicker now on pump gas than before. i was sure some of the good numbers i was seeing before was due to the cold but that doesn't seem to be true.
here is the best comparison gtech i can find. it was 20deg that day and 50deg today. almost identical i was running the same a/f ratio and the same timing.
edit >> that run on the cold day had some race fuel in it and would not run without knock retard at that boost on pump. the warm day run is on pump.
here is the best comparison gtech i can find. it was 20deg that day and 50deg today. almost identical i was running the same a/f ratio and the same timing.
edit >> that run on the cold day had some race fuel in it and would not run without knock retard at that boost on pump. the warm day run is on pump.
So your A/f was exactly same at 9 psi with both 10 and 50 degrees out? The only difference was the KR? That's a tuff one to call, obviously it wanted to make more power, but the ET's should reflect that. Tranny shifted a little later with the extra power maybe? Hmmmmm.........I've got nothing!
TECH Resident
Joined: Jan 2002
Posts: 956
Likes: 0
From: Phoenix, AZ
Take it for what it's worth, but when I first got my Incon kit I asked Dave Inall the same question . . . he alluded to the fact that air will reach a certain point getting colder where your returns will diminish. He did not say what that # was, if it's even possible to nail it down to a specific level.
- Dug
- Dug
Yes you have to pull the timing back. Theres more power in colder air but as that means more cylinder pressure, timing requirements will back off. Youll see it in NA cars, and its amplified in boost cars. Turbo cars especially because they are making max boost at torque peak where there is the max cylinder pressure
Remember more timing isnt always a good thing, if it makes same power with less timing.. its more effecient
Remember more timing isnt always a good thing, if it makes same power with less timing.. its more effecient
Is your MAF maxxed out, or is it truly seeing the increased airflow? On LT1's with high hp FI motors, the maf can get maxxed out. Then you'll need to set the A/F in PE mode on the dyno with a WB. Since the MAF gets maxxed out (lets say at 5000rpm), it cant read increased air at above 5000rpm. If running a summer tune in the car (based on a certain A/F at lets say 75degrees when it was tuned), when the temp drops to 30 degrees outside, the engine will lean out due to more airflow and a nonadjusted fuel delivery (due to MAF not being able to read the extra flow). Maybe your maf is maxing out and leaning out slightly which can cause knock or loss in power (low mph).
Its a matter of dense air and cylinder pressure. You need to have the timing knocked down when the IAT's get down there. Maybe you can do that when the mega starts controlling timing too. Its amazing what 10 degree air will do for power production.
Thread Starter
single digit dreamer
iTrader: (6)
Joined: Mar 2002
Posts: 9,757
Likes: 4
From: omaha ne
i am running megasquirt. right now all i am running if the fuel control. it has WOT a/f targeting and my a/f ratio is always real close to 11.8-1. i may turn that down a hair since i am geting that recomendation from a few people.
my maf maxes in the 3800rpm range sometimes but i can still see the frequency go up so i can get some idea of how much air i am flowing. i am not using the maf to control fueling anymore and should take it out but i just haven't got around to it yet.
the stock pcm is still controling the timing. i could use the temp vs timing tables to pull timing when it is below a certain IAT, that seems like a real good idea at this point.
i would like to play with my timing numbers more and try and dial them in but it is such a pain in the *** with edit. in my truck i actualy have to isolate the pcm from the truck. i wonder if they ever figured that out so i dont have to do that. i never even asked.
my maf maxes in the 3800rpm range sometimes but i can still see the frequency go up so i can get some idea of how much air i am flowing. i am not using the maf to control fueling anymore and should take it out but i just haven't got around to it yet.
the stock pcm is still controling the timing. i could use the temp vs timing tables to pull timing when it is below a certain IAT, that seems like a real good idea at this point.
i would like to play with my timing numbers more and try and dial them in but it is such a pain in the *** with edit. in my truck i actualy have to isolate the pcm from the truck. i wonder if they ever figured that out so i dont have to do that. i never even asked.
Originally Posted by parish8
i wonder if they ever figured that out so i dont have to do that. i never even asked.