PC Makes VFR Run Cooler?

Okay, this is wierd...or maybe not. My red '07 ran in typical VFR fashion - meaning HOT. Here in San Antonio where it's been over 100 freakin degrees every day for almost two months, the temp guage would get up to 220-225 degrees pretty fast on the afternoon commute home, and the fans would come on, etc.

I installed 2-Bros exhaust about three months ago and finally had the Power Commander installed in early July. Aside from the obvious power gains and improved throttle response, I also notice (wonder of wonders!) the bike is running cooler! I'm only hitting that 220+ degree range momentarily when I'm at a traffic light, and as soon as I start moving, it cools back down to the 210 - 215 degree range, and UNDER 200 degrees out on the highway!

I'm thinking that the stock VFR mapping is pretty damn lean, which would cause it run hotter, and by adding the pipes and PC and changing the EFI mapping, it richens the mixture up a bit, thus causing the bike to run cooler.

Comments? My tech knowledge is quite a bit behind a lot of you guys. Am I on or off the mark here?

Thanks,
Dennis

 

hmmm stock tuning is very lean to meet emissions so it could be possible that PC lowered temp a bit.

 

Yep. Running lean means running hot. Gasoline burns cool, oxygen burns hot. Making the mixture a little richer lets it run a little cooler.

 

Doesn't it also mean you would be down on HP then? Engines usually runs its best on leanest fashion without detonation.

 

Your bike will run cooler for sure, if it is set up richer via the power commander,and I am
as sure about that as I am of anything.No, leaner is not better for performance,but it usually helps emissions standards and economy. The way it was told to me ,and I am sure some may disagree; For an engine to run its best,you want a rich fuel mixture,not overly rich so it runs black out the pipes or carbons up the spark plugs.In theory, you want a fuel charge
that has enough fuel so that all the fuel when mixed with all the oxygen in the charge
ignites without burning sooty out the exhausts or carboning up the plugs. Most of our bikes are probably not set up that rich,because its a very fine line between that and running overly rich,also that mixture does not allow for good fuel economy. ed

 

Basically its a reworded version of my answer, rich doesn't make power, yes it makes it run cooler but its not efficient. Like said earlier you will make the most power at its leanest you can run it without detonation or overheating. On a smaller scale, try toying with a 2 stroke RC car engine, they go the fastest running a little lean but it also overheats when you do so, so you have to find a stoichiometric ratio that borders lean enough to run without overheating or detonation. In a gasoline engines its generally 14.7:1, if you're air cooled like Harley then running slightly on the rich side will combat overheating better.

 

Viffer Rider, Oh no its not, if you run lean you run like crap. And this is the last thing I will say about this.Your example about R/C engines, yes they will rev higher when they are lean,but then they have absolutely no power. ed

 

Leaner generally does mean slightly more horsepower, up to a point. That's how a lot of the aftermarket exhaust manufacturers can claim a few extra ponies just from installing their systems. The exhaust is a little more efficient with less backpressure, scavenges a little better, lets the engine run a little leaner, and a few more horsepower mysteriously appear. Of course in most cases it also requires a richening of the mixture to overcome the lean condition and then the gains from the cans goes back down some.

Overly lean means more oxygen in the mix, and that means higher combustion temps. The heat in an oxy/acetylene torch comes from the oxygen, not the acetylene. In extreme conditions something in the cylinder can get hot enough, and stay hot enough between cycles, to cause pre-ignition. Not a good thing.

It's always a balancing act, and less harmful to err on the rich side than on the lean side. Rich means a little lost horsepower, a little less economy (whoopee), and a bit more emissions (oh, wow). Lean can mean detonation and broken upper engine parts.

 

Yea execpt you totally ignored the whole statement I made. I said it will make power to run the leanest WITHOUT detonation and overheating which there is a big difference between running lean and running it lean enough to function without problems.

 

Yea execpt you totally ignored the whole statement I made. I said it will make power to run the leanest WITHOUT detonation and overheating which there is a big difference between running lean and running it lean enough to function without problems. And who said anything about revving higher? The idea is to tune the rc car engine lean enough to run without overheating or detonation it will surely make more power then a rich rc car which typically bog or stalls when it's rich.

 

In the dim recesses of what remains of my memory, gasoline internal combustion motors TYPICALLY made their most power with an air-fuel ratio between 12.7-1 and 13.2-1, or thereabouts, depending on the particular engine. They were less efficient at that ratio, but that was where the most power was extracted. Anything above about 14.7-1 could be problematic in sustaining combustion, although I don't remember if that was under a heavy load or a minimal load. For some reason, 17-1 comes to mind as about the leanest the mixture could be and still spark ignite/combust, period.

That is dated information, however. Combustion chambers have changed a bunch, and microprocessor controlled ignition timing and fuel injection may have re-written those rules. And gasoline has changed, too.

In fact, it might be better to ignore what I just wrote altogether...

 

engine should make the most power when it is running cool and has found the happy medium between too rich and too lean.

 

+1 :thumbsup:

 

LGN yes and no. Idle and cruise is best,for mileage, around 14.7, one atmosphere. 15 is a better # for that with FI. The richer ratios of 13.7-12.7 are for top end under load conditions. Such as drag racing or pulling heavy loads. A lot of new vehicles run on the lean side at idle and cruise for the gas mileage and lower emissions. They can get away with it cause electronics will retard timing if detonation starts.

I worked on a Pro Top Alcohol Funny Car (IHRA) for seven years. We ran the motor right on the edge of detonation most of the time for max power. We used soft rod and main bearings as the sacrificial lambs. Checked them after every run and replaced what was needed. But then again the 40+ lbs of boost heated things up pretty well too. It only needed to last around six seconds though.

 

Back when i was working at a race shop we used lightweight aluminum Howard rods to build the drag motors. 1200hp+ on a 3.2L Nissan VG30DETT V6 does a number on those rods (stretch) though after about 8-9 races. Coupled with Lenco 5spd Airshifts and Mark Williams axles, it turned the best time of 7.44 @ 184mph.

 

Uhhhhhhhhh...wow. Maybe sometimes it's GOOD not to know certain stuff.

I'm just happy with the sound, the power and the cooler running temps. Thanks for all of your input. No, really. (But some of you guys really DO need to get out more often...)

Ride safe, fellas.
Dennis

 

"Be careful what you ask for..." Sorry, Dennis. Get a bunch of gearheads together, and the enthusiasm will rapidly overtake the original point of the discussion. That's a good thing, though. :smile:

And thanks, GreyVF. It used to be than carbureted engines idled fairly rich, like on the order of 10 or 11-1, partly due to poor atomization of the fuel, and partly due to low turbulence in the combustion chamber. Amazing how things have changed...

 

the exhuast with no pc leaned it out then you put on the map which richened it back up...

 

if you think that's something, you should try some slick 50, ur engine will run at no more than 50 degrees.

 

Wha? Why would anyone use PTFE in a engine? Im taking it you're joking?