Here is how much heat affects performance in the RX8
06-23-2004, 09:16 AM
#1
Whuumpha!!
Thread Starter
Join Date: Jan 2004
Location: New Jersey
Posts: 512
Likes: 0
Received 0 Likes
on
0 Posts
Here is how much heat affects performance in the RX8
In April I ran my 8 at the dragstrip and got a 14.8. The temp was 54 and low humidity. I ran again last night to test the CZ1.
My best run WITH the CZ1 was a 15.2. The temp was 107 and 100% humidity. I did some runs with the CZ1 turned off and got a 15.4.
My 60' were all very similar so I think this shows fairly accurately how the heat affects performance.
Anyway, I thought you guys would find this interesting. Here are the slips...
April run (car 202)
Last night...
My best run WITH the CZ1 was a 15.2. The temp was 107 and 100% humidity. I did some runs with the CZ1 turned off and got a 15.4.
My 60' were all very similar so I think this shows fairly accurately how the heat affects performance.
Anyway, I thought you guys would find this interesting. Here are the slips...
April run (car 202)
Last night...
Last edited by Velocity-8; 06-23-2004 at 10:28 AM.
06-23-2004, 09:20 AM
#3
Whuumpha!!
Thread Starter
Join Date: Jan 2004
Location: New Jersey
Posts: 512
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by RobDickinson
Heat will affect performance for sure.
You should be able to counter that some with higher octane fuel but cool/slightly humid air is where its at.
Heat will affect performance for sure.
You should be able to counter that some with higher octane fuel but cool/slightly humid air is where its at.
06-23-2004, 09:25 AM
#6
Human Being
Join Date: Aug 2003
Location: plains
Posts: 554
Likes: 0
Received 0 Likes
on
0 Posts
hmmmm it does seem like heat was the culprit. have you heard of the https://www.rx8club.com/showthread.p...ight=cryogenic at all>?
06-23-2004, 09:30 AM
#7
Registered User
Join Date: Feb 2004
Location: Belgique
Posts: 344
Likes: 0
Received 0 Likes
on
0 Posts
Heat affects WOT engine performances in 2 ways :
1) hotter intake air is less dense, hence less O2, therefore burning less fuel
2) hotter intake air = hotter combustion temperature = propension for knock = spark retarded by the ECU
Some of 2 can be recovered by using higher grade fuel.
1) hotter intake air is less dense, hence less O2, therefore burning less fuel
2) hotter intake air = hotter combustion temperature = propension for knock = spark retarded by the ECU
Some of 2 can be recovered by using higher grade fuel.
06-23-2004, 09:32 AM
#8
Whuumpha!!
Thread Starter
Join Date: Jan 2004
Location: New Jersey
Posts: 512
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by DreRX8
What were the cars that ran against you?
What were the cars that ran against you?
06-23-2004, 09:33 AM
#9
Originally posted by brillo
so how do you counter act this? better radiator? CAI? the intakes don' seem to do much for the car. what other ways can you cool the engine down?
so how do you counter act this? better radiator? CAI? the intakes don' seem to do much for the car. what other ways can you cool the engine down?
But warmer air is (a)warmer and (b)less dense.
(a) causes detonation earlier so timing has to be pinned back more, can be combated by higher octane which has less change of detonating.
(b) Nothing you can do about this. Less dense air has less oxygen in. Same for higher altitude. But does reduce detonation chances.
Its not about the engine being hot - the stock engine cooling will take care of that, its about what parameters the car is dealing with. Effects all cars, F1 whatever.
06-23-2004, 09:36 AM
#10
Whuumpha!!
Thread Starter
Join Date: Jan 2004
Location: New Jersey
Posts: 512
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by RobDickinson
Its not about the engine being hot - the stock engine cooling will take care of that, its about what parameters the car is dealing with.
Its not about the engine being hot - the stock engine cooling will take care of that, its about what parameters the car is dealing with.
06-23-2004, 10:00 AM
#12
Registered User
Join Date: Dec 2003
Location: Dallas, tx
Posts: 143
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by RobDickinson
A CAI may help some.
But warmer air is (a)warmer and (b)less dense.
(a) causes detonation earlier so timing has to be pinned back more, can be combated by higher octane which has less change of detonating.
(b) Nothing you can do about this. Less dense air has less oxygen in. Same for higher altitude. But does reduce detonation chances.
Its not about the engine being hot - the stock engine cooling will take care of that, its about what parameters the car is dealing with. Effects all cars, F1 whatever.
A CAI may help some.
But warmer air is (a)warmer and (b)less dense.
(a) causes detonation earlier so timing has to be pinned back more, can be combated by higher octane which has less change of detonating.
(b) Nothing you can do about this. Less dense air has less oxygen in. Same for higher altitude. But does reduce detonation chances.
Its not about the engine being hot - the stock engine cooling will take care of that, its about what parameters the car is dealing with. Effects all cars, F1 whatever.
Hotter air and a mixture detonates earlier, but less air and a mixture detonates later right? They counteract each other. That is why at higher altitudes you do not need high octane gas. I think that if the incoming air and coolant temp are too close not only timing is being retarded but the mixture is richer. That is why it is impossible to dyno rx8 properly without an incoming air.
06-23-2004, 10:40 AM
#14
Human Being
Join Date: Aug 2003
Location: plains
Posts: 554
Likes: 0
Received 0 Likes
on
0 Posts
https://www.rx8club.com/showthread.p...light=cryogenic
I AM A SHAMELESS BAST*RD- BUT CAN WE PLEASE GET MORE INPUT ON THIS>???????
I AM A SHAMELESS BAST*RD- BUT CAN WE PLEASE GET MORE INPUT ON THIS>???????
06-23-2004, 11:05 AM
#15
Registered User
Join Date: Feb 2004
Location: Belgique
Posts: 344
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Vrimmick
Well,
Hotter air and a mixture detonates earlier, but less air and a mixture detonates later right? They counteract each other. That is why at higher altitudes you do not need high octane gas. I think that if the incoming air and coolant temp are too close not only timing is being retarded but the mixture is richer. That is why it is impossible to dyno rx8 properly without an incoming air.
Well,
Hotter air and a mixture detonates earlier, but less air and a mixture detonates later right? They counteract each other. That is why at higher altitudes you do not need high octane gas. I think that if the incoming air and coolant temp are too close not only timing is being retarded but the mixture is richer. That is why it is impossible to dyno rx8 properly without an incoming air.
06-23-2004, 12:32 PM
#17
Overport
Join Date: Feb 2004
Location: Florida
Posts: 928
Likes: 0
Received 0 Likes
on
0 Posts
Yeah...heat definitely affects the performance. Im to scared to drive my 8 when the temp outside is more than 100 degrees. For some reason i just dont like driving it hard when the temp is so hot...its like im afraid of it overheating!
06-23-2004, 01:00 PM
#18
Whuumpha!!
Thread Starter
Join Date: Jan 2004
Location: New Jersey
Posts: 512
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by smrx8
a neon low 14 that some crap
a neon low 14 that some crap
06-23-2004, 01:04 PM
#19
Whuumpha!!
Thread Starter
Join Date: Jan 2004
Location: New Jersey
Posts: 512
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Doug McGill Jr.
Yeah...heat definitely affects the performance. Im to scared to drive my 8 when the temp outside is more than 100 degrees. For some reason i just dont like driving it hard when the temp is so hot...its like im afraid of it overheating!
Yeah...heat definitely affects the performance. Im to scared to drive my 8 when the temp outside is more than 100 degrees. For some reason i just dont like driving it hard when the temp is so hot...its like im afraid of it overheating!
06-23-2004, 02:01 PM
#21
Registered User
Join Date: Dec 2003
Location: South Florida
Posts: 490
Likes: 0
Received 0 Likes
on
0 Posts
Good stuff, Velocity 8. I knew heat affected performance, but now we know exactly how much, Thank You. Here in south Florida the heat and humidity is very intense and is a performance killer for any car. I do notice a noticeable performance increase at night when it is cooler. As for the SRT-4, they are not crap, if you like to drag, which is what the car was set up to do via Mopar. It is the best performance per dollar car period. They are very easy to get to run into the 12s while keeping some green in your wallet. The fact is high heat and humidity effects and intercooled turbo even more, especially after multiple runs and thus is the reason for the 14.5 1/4 mile time. I guess if anyone is going to figure something out that might overcome this is Jeff (MazdaManiac) Maurice (canzoomer) or Paul Yaw. I'd imagine the temp and airflow sensor would have to be tweeked and some preventive measure against detonation.
06-23-2004, 07:27 PM
#22
Senior Member
Join Date: Dec 2003
Location: So. California
Posts: 105
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by IKnowNot'ing
Heat affects WOT engine performances in 2 ways :
1) hotter intake air is less dense, hence less O2, therefore burning less fuel
2) hotter intake air = hotter combustion temperature = propension for knock = spark retarded by the ECU
Some of 2 can be recovered by using higher grade fuel.
Heat affects WOT engine performances in 2 ways :
1) hotter intake air is less dense, hence less O2, therefore burning less fuel
2) hotter intake air = hotter combustion temperature = propension for knock = spark retarded by the ECU
Some of 2 can be recovered by using higher grade fuel.
Okay now - quite often, when the air gets hot, it's an indication that the barometer (i.e. the amount of weight the air weighs which is indicative of how much air is above you) is higher. This then, means denser air, not “less dense” air.
Most of us know that if you are at sea level, or hey even better, below sea level like in Death Valley, that your car is going to run faster than it will at 10,000 Feet. The average atmospheric pressure at sea level is 29.92. Velocity’s best run with the CZ1 was at 30.83 (which is below sea level).
I suspect one of two things. Either the CZ1 modification slowed the car down (not likely, according to what I read on this board), or it is the humidity! At 100%, were you under water or something? Around my house in California, when it’s 87% humidity, there is a steady mist and the ground is wet. That said, I wonder if your tires had enough grip for a drag speed test.
06-23-2004, 07:40 PM
#23
Whuumpha!!
Thread Starter
Join Date: Jan 2004
Location: New Jersey
Posts: 512
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Zeltar
I suspect one of two things. Either the CZ1 modification slowed the car down (not likely, according to what I read on this board), or it is the humidity! At 100%, were you under water or something? Around my house in California, when it’s 87% humidity, there is a steady mist and the ground is wet. That said, I wonder if your tires had enough grip for a drag speed test.
I suspect one of two things. Either the CZ1 modification slowed the car down (not likely, according to what I read on this board), or it is the humidity! At 100%, were you under water or something? Around my house in California, when it’s 87% humidity, there is a steady mist and the ground is wet. That said, I wonder if your tires had enough grip for a drag speed test.
06-23-2004, 08:50 PM
#24
Registered
Join Date: Aug 2003
Posts: 589
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by IKnowNot'ing
Heat affects WOT engine performances in 2 ways :
1) hotter intake air is less dense, hence less O2, therefore burning less fuel
2) hotter intake air = hotter combustion temperature = propension for knock = spark retarded by the ECU
Some of 2 can be recovered by using higher grade fuel.
Heat affects WOT engine performances in 2 ways :
1) hotter intake air is less dense, hence less O2, therefore burning less fuel
2) hotter intake air = hotter combustion temperature = propension for knock = spark retarded by the ECU
Some of 2 can be recovered by using higher grade fuel.
06-23-2004, 08:59 PM
#25
Registered User
Join Date: Sep 2003
Location: Apex, North Carolina
Posts: 56
Likes: 0
Received 0 Likes
on
0 Posts
Did anyone other than me notice that the dates on the time slips showed June 23, 2004. Their date stamp must be off by one day. Maybe the effect of the 2004 leap year.