Air Temperature And Hp

I went for a nice ride today and was really having a good time. I noticed something that I have been trying to figure out and wonder about the correlation.

Twice today, I took off from stopped or near stopped, smoothly rolled on the throttle to the stop and when the bike hit vtec, the front wheel went skyward. :wheel:

These were not 'pops' but nice smooth continue to pull power wheelies. So, the question is, what is the relationship between HP and air temperature? I seem to notice this occurs much more frequently in cooler weather, but not sure if it matters that much. Most of the time, I cannot get the bike to wheelie even if I hammer the throttle.

One note, is I have a PCIII w/ coyze's map, no 02's and 5th gen headers if any of that matters.

I am no expert...but I did sleep at a Holiday Inn last night.

My VERY layman's concept is any horsepower gains would have to do with air density.

Air density = air pressure/(gas constant * air temperature)

Colder air increases air density so you will see slight HP gains in colder air temperatures. You should also see slight HP losses as you increase elevation (air pressure decreases).

I would be surprised if either would make enough of a difference that you could feel it. But I don't know that for sure.

[image: View Post]turtlecreek, on Sep 23 2008, 04:30 PM, said:

I went for a nice ride today and was really having a good time. I noticed something that I have been trying to figure out and wonder about the correlation.

Twice today, I took off from stopped or near stopped, smoothly rolled on the throttle to the stop and when the bike hit vtec, the front wheel went skyward. :wheel:

These were not 'pops' but nice smooth continue to pull power wheelies. So, the question is, what is the relationship between HP and air temperature? I seem to notice this occurs much more frequently in cooler weather, but not sure if it matters that much. Most of the time, I cannot get the bike to wheelie even if I hammer the throttle.

One note, is I have a PCIII w/ coyze's map, no 02's and 5th gen headers if any of that matters.

Cooler Air = Denser Air = Mo Hospawah and better running! :fing02:

That is why turbo motors have intercoolers to cool the pressurized air charge.
And that's why the 4th gen has those big beautiful Naca ducts to lower under fairing temps = Mo Hospawah!! = fastest gen VFR!! :biggrin: ;p

Beck
95 VFR

[image: View Post]Slippin, on Sep 23 2008, 04:00 PM, said:

I am no expert...but I did sleep at a Holiday Inn last night.

My VERY layman's concept is any horsepower gains would have to do with air density.

Air density = air pressure/(gas constant * air temperature)

Colder air increases air density so you will see slight HP gains in colder air temperatures. You should also see slight HP losses as you increase elevation (air pressure decreases).

I would be surprised if either would make enough of a difference that you could feel it. But I don't know that for sure.


http://www.vfrdiscussion.com/forum/style_emoticons/default/%201.gif What he said, best power is with cool dense air! :fing02:

Now the power wheelie is a strange phenomena on a VFR! :unsure:
Many times I've had just a throttle setting at less than full and just letting the bike accelerate and the front end just comes up unexpectedly. :wheel:
Now that feels great so at the next stop I pin it full expecting better results and it won't even lift the wheel period??? :mellow:

There seems to be some ideal throttle opening that matches some other ideal settings and the bike just rips, try to repeat with full throttle and no go? :rolleyes:

http://www.zx11.info/zx11/aero.htm

Quote

Temperature: How does it effect Horsepower?
For every 11 degrees Fahrenheit or 6 degrees Celsius change at the carburetors, a 1 percents change in horsepower can be realize if jetting is also corrected for that temperature. Cooler air is more dense and therefore has more oxygen per cubic foot than warmer air. More oxygen allows for more fuel to be burnt, and therefore more power to be produced.

Example:

If the air ingested by the engine is 66 degrees Fahrenheit cooler than the surrounding air, (engine heat!?!) then a 6 percent increase in power can be realized with proper jetting.

Cooler, denser, damper.............you got the makins'........... :fing02:

Uh, Dale........you sometime scuff body panels without wheelies......might wanna' wait on a really hot, thin, dry day to ride...... :biggrin:

[image: View Post]skuuter trash, on Sep 23 2008, 05:36 PM, said:

Cooler, denser, damper.............you got the makins'........... :fing02:

Uh, Dale........you sometime scuff body panels without wheelies......might wanna' wait on a really hot, thin, dry day to ride...... :biggrin:



YEP!

i knew cool dense air is more, but didnt have a sense on how much. so basically, the cool temp today doesn't explain why i seemed to have more power.....

BR, must be the same thing we have talked about. something about certain situation, when you smoothly roll on, it seems to have better reponse. i will say on the best one, the throttle was ahead of the rpms...if that makes sense. i quickly, but smoothly rolled on to the stop in 2nd gear and the motor lagged, but when it hit vtec, its like i picked up 10hp as the wheel just pull right up very smoothly....


some japanese designer somewhere is laughing about how he put a random function generator in the cpu that bumps the hp every so often :huh:

[image: View Post]skuuter trash, on Sep 23 2008, 04:36 PM, said:

Cooler, denser, damper.............you got the makins'........... :fing02:

Uh, Dale........you sometime scuff body panels without wheelies......might wanna' wait on a really hot, thin, dry day to ride...... :biggrin:


i figured that its been so long since i've scraped paint, i need to start 'pushing the envelope' again :offtopic: :biggrin:

[image: View Post]skuuter trash, on Sep 23 2008, 02:36 PM, said:

Cooler, denser, damper drier.............you got the makins'........... :fing02:

Uh, Dale........you sometime scuff body panels without wheelies......might wanna' wait on a really hot, thin, dry day to ride...... :biggrin:

2 outta 3 ain't bad.........if your name is Meatloaf. You obviously didn't do the reading assignment I linked to in my last post. ;)

We are definitely on to something here; I've noticed a change (a very welcome one) in the bikes behaviour on some cooler mornings. Particularly when the air temp reads between 8 to 13C the bike runs even more smoothly than it already does but with a bit more poke in the 5-9k rpm range.

It's just nice to now know the science behind it. But with all that techno stuff going on in that 6th gen frame, there probably is a perfect set of parameter settings which makes our Vtec�s turn into a bit more of a hooligan :wheel:

More air=more power

Kinda like a torocharger :biggrin:

:offtopic: I'd like a toro charger. :blush: But then again I need to learn how to actually ride better...

THEN I CAN GET A TORO CHARGER!!!!

More air=more power=LEO problems=wife problems=sell motorcycle=no torocharger..DAM....

coupla things:

If you have ever tried to tune an old triumph twin, you will know that when the air is cold and damp, that thing just purrs with a descearnably different and more pleasing note. Notice this occurs both when the air is damper and more dense, but also when the weather is like England, where they were designed and built.

Also, I remember reading about a two stroke race tuner who was having problems jetting because half the track was in the sun and the other half in a cool damp shade. he couldnt get it perfect so he had to compromise.

Now, these two examples against modern fuel injection really has no cooralation, but the theory is the same.

[image: View Post]GGray, on Sep 24 2008, 11:16 AM, said:

More air=more power

Kinda like a torocharger :biggrin:

One issue with compressing more air into a engine viva Turbo/supercharger is that compressing air creates unwanted heat, this is where intercoolers come in. To a point the more you cool the charge the more Boost you can run w/o detonation! :fing02:

Yup...Got a few turbo cars hanging around :fing02: M3turbo, 535isturbo... NEED ONE! ALL are 4SALE!!!

I thought a good upgrade to the torocharger project would be to substitute a water to air intercooler since I think there is enough room on the bike to do it...Adds weight though...

Low boost is okay non intercooled..Larger oil cooler will do...

A flux capacitor would be even better but it might not have much range with the extension cord :goofy:

[image: View Post]GGray, on Sep 24 2008, 01:39 PM, said:

Yup...Got a few turbo cars hanging around :fing02: M3turbo, 535isturbo... NEED ONE! ALL are 4SALE!!!

I thought a good upgrade to the torocharger project would be to substitute a water to air intercooler since I think there is enough room on the bike to do it...Adds weight though...

Low boost is okay non intercooled..Larger oil cooler will do...

A flux capacitor would be even better but it might not have much range with the extension cord :goofy:

:biggrin: I think Toro is working/looking at a cooler of some type as a kit option in the future or even build on into that air plenum he has as part of the current kit! :fing02:

ps I use to do a lot of Turbo stuff on cars messing with different injectors, fuel reg.s, CPU's, water injection, intercoolers, compressor sizes, etc., now my only turbo is an older MB diesel. :fing02:

I think their is more involved then just pure HP. I too have experienced certain times the front end is light as can be, while others I have to force it if I want it to come up. Mid 70's and low humidity are where my bike runs the best, and it is a noticeable difference. But just dropping temp doesn't make it feel like it runs better. so when it is 50 out, it doesn't feel faster than 70. I think this is because of wheelspin. I've been told my wheel spins quite a bit, even though I don't notice it at times. So colder temps probably means more wheelspin and more hp. I guess mid 70's are where I get the best traction and hp.
That's what the temp is right now....man I wish I was out there.

Could it be a combination of sitting slightly farther back onthe seat and the cooler temps...A slight weight shift might cause it...

:+1: Similar story... I have noticed this with both the VFR and also my dirtbike. Accelerations seem MUCH more noticable when it is COOLER outside but not necessarily COLD. I was pulling away from a redlight in Murfreesboro about to head East on 24 to Puckett's one sunday morning and a Mustang GT was being obnoxious next to me and floored it and I just coasted thru 1st but after I shifted into second I just rolled on it 7/8 throttle on a cool morning to "show him who's boss for about 2.5 seconds" and out of NO WHERE the front wheel goes skyward to the balance point! :wheel: I have NEVER had a roll on 2nd gear power wheelie go that high with stock gearing. I rode it out longer than I thought I would and after I set it back down I had a grin from ear to ear and the thought, "I will just pretend like i TRIED to do that" :laugh:

Only thing that I could think of that made sense was the cool air density thing and that hot air expands.... so when that cool air gets ignited in the cylinder it expands more thus creating a little more power ????? very novice assumption here.

[image: View Post]Baileyrock, on Sep 23 2008, 04:16 PM, said:

[image: View Post]Slippin, on Sep 23 2008, 04:00 PM, said:

I am no expert...but I did sleep at a Holiday Inn last night.

My VERY layman's concept is any horsepower gains would have to do with air density.

Air density = air pressure/(gas constant * air temperature)

Colder air increases air density so you will see slight HP gains in colder air temperatures. You should also see slight HP losses as you increase elevation (air pressure decreases).

I would be surprised if either would make enough of a difference that you could feel it. But I don't know that for sure.


http://www.vfrdiscussion.com/forum/style_emoticons/default/%201.gif What he said, best power is with cool dense air! :fing02:

Now the power wheelie is a strange phenomena on a VFR! :unsure:
Many times I've had just a throttle setting at less than full and just letting the bike accelerate and the front end just comes up unexpectedly. :wheel:
Now that feels great so at the next stop I pin it full expecting better results and it won't even lift the wheel period??? :mellow:

There seems to be some ideal throttle opening that matches some other ideal settings and the bike just rips, try to repeat with full throttle and no go? :rolleyes:

Yeah, you just don't seem like the :squid: ly wheelie type, Kevin. I can't imagine you doing that on purpose!! :blink:

Oh, and Dale, I told you the answers this morning.....have a good trip! :fing02:

[image: View Post]Baileyrock, on Sep 24 2008, 08:00 PM, said:

One issue with compressing more air into a engine viva Turbo/supercharger is that compressing air creates unwanted heat, this is where intercoolers come in. To a point the more you cool the charge the more Boost you can run w/o detonation! :fing02:

Which sometimes leads to extreme hack jobs like this. Poor Duc :blink:
http://static.blogo.it/motoblog/999R_turbo_01_main.jpg

[image: View Post]Bent, on Sep 24 2008, 08:25 PM, said:

Yeah, you just don't seem like the :squid: ly wheelie type, Kevin. I can't imagine you doing that on purpose!! :blink:


You are correct, if my front wheel ever comes off the ground, it's purely by accident! :rolleyes:
I think it's that Vtec thingy.