Ulysses
Enthusiast
Heat and humidity can contribute a lot to robbing your engine of power.
Question on loss of power when car gets hot
- Thread starter Ulysses
- Start date
Serious Eric
Enthusiast
Could be that where you live, and it's 100 below zero most of the time vipers DO make 550 Hp and that now that the permafrost has melted you're just experiencing normal paltry 450 Hp viper behavior?
Nahh, sounds like something is actually wrong. Take it in and have the A/F mixture checked.
I've found that my vipers have actually NOT been very sensitive to temperature ... not nearly so much as some other cars I've owned. Had a 5.0L cobra that was hugely sensitive to temp/press ... 50 Hp difference between 35F and 95F. The viper hardly seems to care. It's been over 100F for the last 25 days straight here and I can still smoke the tires in the first three gears.
I've found that my vipers have actually NOT been very sensitive to temperature ... not nearly so much as some other cars I've owned. Had a 5.0L cobra that was hugely sensitive to temp/press ... 50 Hp difference between 35F and 95F. The viper hardly seems to care. It's been over 100F for the last 25 days straight here and I can still smoke the tires in the first three gears.
Toronto_ACR
Enthusiast
Actally the average temperature here is always about 2 or 3 degrees below what New York city has in the winter. But you wouldnt know that since your brain got fried a long time ago. There are a lot of good Texans out there that are good friends of mine. But unfortunately a small minority of them are country hicks that eat grits and hamhocks and some of them make enough money selling the stuff to actually buy a Viper. nah it must be that you had your head punctured trying to hog tie a bull when you were small.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Eric Schieve:
Could be that where you live, and it's 100 below zero most of the time vipers DO make 550 Hp and that now that the permafrost has melted you're just experiencing normal paltry 450 Hp viper behavior?
Nahh, sounds like something is actually wrong. Take it in and have the A/F mixture checked.
I've found that my vipers have actually NOT been very sensitive to temperature ... not nearly so much as some other cars I've owned. Had a 5.0L cobra that was hugely sensitive to temp/press ... 50 Hp difference between 35F and 95F. The viper hardly seems to care. It's been over 100F for the last 25 days straight here and I can still smoke the tires in the first three gears.
<HR></BLOCKQUOTE>
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Eric Schieve:
Could be that where you live, and it's 100 below zero most of the time vipers DO make 550 Hp and that now that the permafrost has melted you're just experiencing normal paltry 450 Hp viper behavior?
I've found that my vipers have actually NOT been very sensitive to temperature ... not nearly so much as some other cars I've owned. Had a 5.0L cobra that was hugely sensitive to temp/press ... 50 Hp difference between 35F and 95F. The viper hardly seems to care. It's been over 100F for the last 25 days straight here and I can still smoke the tires in the first three gears.
<HR></BLOCKQUOTE>
Toronto_ACR
Enthusiast
No I am not edgy it is just when someone makes a sarcastic remark like that knowing full well that I am only a 3 hour car drive away from Detroit City. If he does not like anyone from outside the border then he should keep it to himslf and say nothing.
Anyway thanks for your reply. But if the car actually does not lose any power when it is hot then why does my and I am sure everyone elses car lose power when on a dynamometer. My first run on the dyno showed 422 rwhp completely stock. But my second run showed 414rwhp 5 minutes later. But I find that on very hot days the car is very lazy. If your car is ok then my problem must be partly caused by my service engine light being on since since I changed my headers and exhaust. Thanks Florida
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by impetuous Black viper:
Toronto ACR ever consider changing to Decaf? You sound a little edgy.
I would get the car check out. I live in the Florida heat and the car performs the same even when its cool out.
<HR></BLOCKQUOTE>
Anyway thanks for your reply. But if the car actually does not lose any power when it is hot then why does my and I am sure everyone elses car lose power when on a dynamometer. My first run on the dyno showed 422 rwhp completely stock. But my second run showed 414rwhp 5 minutes later. But I find that on very hot days the car is very lazy. If your car is ok then my problem must be partly caused by my service engine light being on since since I changed my headers and exhaust. Thanks Florida
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by impetuous Black viper:
Toronto ACR ever consider changing to Decaf? You sound a little edgy.
I would get the car check out. I live in the Florida heat and the car performs the same even when its cool out.
<HR></BLOCKQUOTE>
Serious Eric
Enthusiast
WOW!! In the interest of North American harmony let me say this: You have completely misunderstood my message. Yes a *slight* amount of sarcasm, albeit good-natured and only intended as an 'all-in-good-fun' jibe at a neighbor. Notice the
icon? It means 'just kidding'. If you had been from N. Dakota I probably would have said the same, since compared to where I live, that lattitude and yours see low temperature extremes that we never imagine.
Hidden (not too deeply I hope) in that very small joke was my POINT which I reiterate (I was actually trying to help you out). You DO see much lower temps through much of the year than I do, therefore while it's POSSIBLE that your car may experience Hp increases in the winter that I'm not familiar with, I kinda doubt it. I went on to state that all in all, my viper experience shows me that the car is NOT very sensitive to temp extremes, even in the (exageration coming) "brain-frying" heat of Texas.
Was just trying to tell you that I think there may be something actually wrong with your car ... the behavior does not sound normal. Point the howitzers somewhere else, we weren't planning to invade.
Hidden (not too deeply I hope) in that very small joke was my POINT which I reiterate (I was actually trying to help you out). You DO see much lower temps through much of the year than I do, therefore while it's POSSIBLE that your car may experience Hp increases in the winter that I'm not familiar with, I kinda doubt it. I went on to state that all in all, my viper experience shows me that the car is NOT very sensitive to temp extremes, even in the (exageration coming) "brain-frying" heat of Texas.
Was just trying to tell you that I think there may be something actually wrong with your car ... the behavior does not sound normal. Point the howitzers somewhere else, we weren't planning to invade.
treynor
Enthusiast
[all together now] Blame Canada, Blame Canada! Yad da dah da dah da dah...
Seriously though, I've found (on the dyno) that power is more affected by coolant temp than by air temp. Coolant <200F == power good, raspy exhaust note from advanced timing, etc. Coolant >210F == power bad, mellow exhaust note, -40 HP on the dyno. Air temps seem to lead to a 1-2% HP diff per 10 deg F.
Ben "Dyno ****(tm)" Treynor
Seriously though, I've found (on the dyno) that power is more affected by coolant temp than by air temp. Coolant <200F == power good, raspy exhaust note from advanced timing, etc. Coolant >210F == power bad, mellow exhaust note, -40 HP on the dyno. Air temps seem to lead to a 1-2% HP diff per 10 deg F.
Ben "Dyno ****(tm)" Treynor
hey toronto i've noticed the same thing here in wisconsin. this heat and humidity is rough. i've noticed a little trade off...when it gets cooler there's that little increase in power, but at the same time the tires also break a little easier. oh well.
8AVETTE
Enthusiast
I have a 01 ACR and today it was 94 outside and I sure felt like I was driving a Mustang, not the acceleration I normally get. But I recently got the dreaded check engine light from the BTR headers and exhaust I installed a few weeks back. Definitely down on power. Is there a fix yet?
Tim
Viper Owner
Just a note that all normally aspirated engines will loose 3% of their rated horsepower per 1000-ft increase in density altitude.
Those calculations are based on a standard barometric pressure of 29.92 inches of mercury and 15 deg Celsius at sea level. I will try and get the hand calculations to work this out and put on here.
There are also programmable calculators that can be programmed for this as well as small slide rules that Pilots use to determine density altitudes for performance. In a nutshell as temperatures climb performance will decrease
Those calculations are based on a standard barometric pressure of 29.92 inches of mercury and 15 deg Celsius at sea level. I will try and get the hand calculations to work this out and put on here.
There are also programmable calculators that can be programmed for this as well as small slide rules that Pilots use to determine density altitudes for performance. In a nutshell as temperatures climb performance will decrease
Toronto_ACR
Enthusiast
I apologize for my remark. Your right I was too quick to snap back and I apologize for taking it the wrong way. I quess we Torontonians have lost our sense of humour since we did not get the Olympics.
As for the power yes I do notice a different feel. Not a huge feel but maybe I might be making something out of nothing. One day I can burn the tires loose and the next day I cannot burn the tires even on a downshift. Is this normal or do I have a problem.
Thanks
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Eric Schieve:
WOW!! In the interest of North American harmony let me say this: You have completely misunderstood my message. Yes a *slight* amount of sarcasm, albeit good-natured and only intended as an 'all-in-good-fun' jibe at a neighbor. Notice the
icon? It means 'just kidding'. If you had been from N. Dakota I probably would have said the same, since compared to where I live, that lattitude and yours see low temperature extremes that we never imagine.
Hidden (not too deeply I hope) in that very small joke was my POINT which I reiterate (I was actually trying to help you out). You DO see much lower temps through much of the year than I do, therefore while it's POSSIBLE that your car may experience Hp increases in the winter that I'm not familiar with, I kinda doubt it. I went on to state that all in all, my viper experience shows me that the car is NOT very sensitive to temp extremes, even in the (exageration coming) "brain-frying" heat of Texas.
Was just trying to tell you that I think there may be something actually wrong with your car ... the behavior does not sound normal. Point the howitzers somewhere else, we weren't planning to invade.
<HR></BLOCKQUOTE>
As for the power yes I do notice a different feel. Not a huge feel but maybe I might be making something out of nothing. One day I can burn the tires loose and the next day I cannot burn the tires even on a downshift. Is this normal or do I have a problem.
Thanks
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Eric Schieve:
WOW!! In the interest of North American harmony let me say this: You have completely misunderstood my message. Yes a *slight* amount of sarcasm, albeit good-natured and only intended as an 'all-in-good-fun' jibe at a neighbor. Notice the
Hidden (not too deeply I hope) in that very small joke was my POINT which I reiterate (I was actually trying to help you out). You DO see much lower temps through much of the year than I do, therefore while it's POSSIBLE that your car may experience Hp increases in the winter that I'm not familiar with, I kinda doubt it. I went on to state that all in all, my viper experience shows me that the car is NOT very sensitive to temp extremes, even in the (exageration coming) "brain-frying" heat of Texas.
Was just trying to tell you that I think there may be something actually wrong with your car ... the behavior does not sound normal. Point the howitzers somewhere else, we weren't planning to invade.
<HR></BLOCKQUOTE>
99 GTS Snakeman
Enthusiast
Toronto ACR,
I have noticed a drop in HP the past few days.
The temperature in Ottawa has been very hot and humid.
My snake feels a lot more powerful when the air is cooler.
Less than 20 C is ideal for my machine.
I have a Roe Racing VEC1 and AF meter.
It looks like the mixture is running a little richer
during the past few days. I was reading AF ratio of 13.2:1 (optimal for maximum horsepower) under WOT when it was cooler.
I am now reading closer to 12.5:1 under WOT during these hot humid days - probably because the oxygen is thinner. The VEC1 settings haven't changed.
Do you ever make it up to Ottawa?
Cheers,
Brent
I have noticed a drop in HP the past few days.
The temperature in Ottawa has been very hot and humid.
My snake feels a lot more powerful when the air is cooler.
Less than 20 C is ideal for my machine.
I have a Roe Racing VEC1 and AF meter.
It looks like the mixture is running a little richer
during the past few days. I was reading AF ratio of 13.2:1 (optimal for maximum horsepower) under WOT when it was cooler.
I am now reading closer to 12.5:1 under WOT during these hot humid days - probably because the oxygen is thinner. The VEC1 settings haven't changed.
Do you ever make it up to Ottawa?
Cheers,
Brent
Toronto_ACR
Enthusiast
thanks for your answer Brent. Does your air fuel meter also allow you to add or remove fuel from your car. So your fuel meter is telling you that it is running richer when hot. Correct me if I am wrong but does a car not make not more power if running richer. I guess it is running richer because the air is not as dense.
To answer your question I don't make it to Ottawa to often but I am going there within the next 8 weeks once I get back from Michigan in late september. Email me your number and maybe I can hook up and check out your beast.
To answer your question I don't make it to Ottawa to often but I am going there within the next 8 weeks once I get back from Michigan in late september. Email me your number and maybe I can hook up and check out your beast.
Toronto_ACR
Enthusiast
Treynor what is the best way to get a better performing radiator. I would very much like to cool my coolant temp more because when driving in the city my feet are frying down there. Some days the heat is unbearable.
Thanks
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by treynor:
[all together now] Blame Canada, Blame Canada! Yad da dah da dah da dah...
Seriously though, I've found (on the dyno) that power is more affected by coolant temp than by air temp. Coolant <200F == power good, raspy exhaust note from advanced timing, etc. Coolant >210F == power bad, mellow exhaust note, -40 HP on the dyno. Air temps seem to lead to a 1-2% HP diff per 10 deg F.
Ben "Dyno ****(tm)" Treynor<HR></BLOCKQUOTE>
Thanks
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by treynor:
[all together now] Blame Canada, Blame Canada! Yad da dah da dah da dah...
Seriously though, I've found (on the dyno) that power is more affected by coolant temp than by air temp. Coolant <200F == power good, raspy exhaust note from advanced timing, etc. Coolant >210F == power bad, mellow exhaust note, -40 HP on the dyno. Air temps seem to lead to a 1-2% HP diff per 10 deg F.
Ben "Dyno ****(tm)" Treynor<HR></BLOCKQUOTE>
treynor
Enthusiast
If you aren't exceeding your cooling system's capacity -- and you're not when you're in traffic -- then the first thing to do is get Roe Racing's fan control kit and have him wire it up so it will turn on even when the car is running. This setup will turn on your fan when your coolant hits 200 degrees, and turn it off when it drops to 180. If you are getting above your thermostat's setting (190) while moving at any real speed, then you're best off getting an upgraded radiator. I put a Fluidyne radiator in my car (available at Parts Rack, of course) which was quite a bit larger than stock, and my car now sits at thermostat temp in everything but stop-n-go traffic.
FWIW, the heat you are feeling around your feet probably has everything to do with engine bay and road heat, and nothing to do with coolant temp. You could try putting additional insulation on the car's undercarriage to help shield it.
FWIW, the heat you are feeling around your feet probably has everything to do with engine bay and road heat, and nothing to do with coolant temp. You could try putting additional insulation on the car's undercarriage to help shield it.
Toronto_ACR
Enthusiast
Is anyone else having the same problem as i am. It seems to me that the power level of the car goes up and down like a yoyo. One day it feels very powerful and the next day it feels like a slug. The tires dont burn out and It feels like the car is down about a hundred horsepower. can someone tell me if they are having the same problem. Can heat effect it that much
Toronto_ACR
Enthusiast
dgeviper1 you have a very good point. In all this heat not only is their a small power loss but I bet the tires are a lot harder to spin out on . They are much stickier than they would be in even 60 degree weather.
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