400Eric said:
Why not post the "more info" here so that all can share in the knowledge?
Well, I didn't want to say "Gerry, you are totally wrong" in public, but oh well - Gerry, you're wrong!
Copy/paste of emails follows, edited slightly for clarity:
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Hi Gerry,
I didn't want to put this on the forum, but there is no freakin' way the E500E changes 0.1 second per 10° air temp change. Never. Doesn't do it. I have over five hundred runs of data on the E500 and another couple hundred (yes, hundred) from both the 500E and E420 proving this. I've seen 20-30 degree swings in ambient temp on the same day change ET's less than a tenth total, less than one MPH. It's not fair to compare different days as the pressure / humidity etc can be drastically different (although it can change a lot the same day, it's usually minor changes on the same day within a 4-6 hour period). I've watched other cars (especially carbureted muscle cars) go faster or slower as temp changes 10-20 degrees, but the M119 simply does not follow ambient temps like many other cars do. You can go over the data on my site and see for yourself.
I suspect that humidity level has much more effect than temp, but I don't yet have enough data to prove this. I also found that the DA has relatively little effect as well (based on data collection in 2010), the car didn't go faster as DA dropped, or slower as DA increased. There was a tech article about this exact topic in National Dragster last year; basically confirming the same thing about DA - each car can react to different things in a different way. But a cold day does not automatically produce superfast runs, nor does a wam day always produce slow ones. Very cold or very hot will usually make the worst numbers but for different reasons: when very cold, there is wheelspin due to cold pavement - can't hook up. When very hot, the computers spoil the party and the engine makes less power. There's a happy medium in the middle. I prefer 60-75F for optimum conditions.
Please note that this only applies with non-NOS runs; with NOS there could be a totally different reaction as the laughing gas cools the intake and the car could behave very differently. When I eventually get NOS on my car I'll be curious to see how it reacts.
BTW - this is assuming normal cool-down time. In late rounds where there may only be 10-15 minutes between runs, I have to increase my dial (slower time) as it's not possible to cool the engine. The car can slow as much as two tenths when hot compared to a "cool" run (but it doesn't always!). It almost never runs faster when hot-lapped but belive it or not, that has happened to me once or twice. Very, very rare though and it's only by a couple hundredths.
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Dave,
Well, I've probably had 300+ drag runs under my belt with my E500 (normal and NOS aspiration), 560SEC, 300SEL 6.3 and 450SEL 6.9 and across all of these cars (all at Portland International Raceway and Seattle International Raceway) it's what I observed as a rule of thumb -- that for each 10-degree drop in temp, there is a corresponding 0.1 second drop in ET. You can as a rule of thumb say the same for each ~100 lbs you remove from the car.
Sure as you say there are likely other factors, but my observation has always been that the E500 is MUCH happier in colder temperatures (winter) than at the height of summer heat, all other things being the same. Though my car handles summer temps quite well here in Houston, it mirrors my experience in Portland in liking colder temps better.
My data / observations are very unscientific and of course each car, not to mention track, climate and so forth are different. But it's what I've seen in very general terms. The big variable is technique -- each run is different. But I can tell you with EVERY car I've owned and drag raced that I have my very best (lowest times) runs when the weather is coldest - at the very beginning or more likely very END of the season -- October time frame.
I don't know you why didn't post your response to the board. I don't mind as it's a good discussion -- wouldn't make me upset in the least. My observations are just different, not as studied and scientific as yours (I've never competed so not had to estimate times) but I do in a general sense stand behind my statements.
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Hi Gerry,
I forgot to mention - my data is using a '92 LH module almost exclusively, which goes open-loop at WOT. The '94 LH could change more... hadn't thought of that. Also, the M117 and older engines could vary more based on ambient temp. I cannot make any statements about engines other than the 119.97x series.
But in the .036 there is just nothing near a 0.1 ET change per 10°, shoot, I don't even seen 0.1 with 20°+ change (warmer OR colder). I do see that ~0.1 change in ET / ~1 mph based on weight though, 100 lbs makes a very clear difference in performance, every time.
By comparison, ambient temp absolutely does not. If I run the car at 60F and then the next day at 85F, with no other change, the performance will be nearly identical (within a few hundreths ET, few tenths MPH). But if I pull 100lbs of weight out of the car and run the next day at the identical ambient temp, THAT will improve performance every time.
Yes it's true that in general the car will run quicker in spring/fall, but not by a drastic margin; and I've never ever ever had my peak/best numbers in very cool temps.
I basically have no data out of 700+ runs that supports the theory of an .036/.034 (specifically M119.97x) always running quicker in low ambient temps (say, 45-55F) compared to medium temps of 70-85F. At least not with a '92 LH module. Maybe with the '94 module that is true...?
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Dave,
I didn't note that -- ALL of my E500 data was using the stock 1994 LH module. I didn't install the brand-new 1992 LH unit I got in the UK with Talbir until after my drag racing days were over (lo about 2005).
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End of off-forum discussion. Group hugs all around now!
Imagine being able to spank the Sauceman with a kanppy Volvo station wagon!
Nothing drastically new in my data; just more of the same as I described above. I'm tracking pressure this year instead of DA, initial results (from two days) seem to indicate that is more useful than DA, but I'll need a lot more days to prove that trend. Sorry, don't know anything about Volvos. Boosted cars are still affected by atmospheric conditions at launch, before boost builds; and to a lesser extent otherwise... but you are right, it's far less than with non-boosted cars.
