Dyno run resultls for '99 VFR

I heard there was a bike night and dyno runs are only 20 bucks so why the hell not.

Here's my bike getting ready for the run:


And here's the dyno printout:


Note that the blue line is from running the bike in 4th gear and the red line is in 6th gear. As you can see it tops out at 94.3 horsepower and 163.16 mph. I got to say I'm impressed, I was expecting 90ish horsepower and a 140ish top speed. The only mods done to this bike is an aftermarket exhaust (vance & hines stainless), performance air filter (BMC), and going down 1 tooth on the front sprocket.

 

Cool beans, thanks for posting up.


Though...the top speed data is trash for real world performance since it neglects air resistance. Nice to know what the max top speed is though in a near perfect conditions...

Was it a hot day, or just ridiculously hot in the trailer? 100F?

 

Yeah it was a pretty hot day, at least 90s and the trailer was warmer due to the bikes running and all. I know what you mean about the air resistance, I thought that with going down 1 tooth in the front the top speed would be reduced quite a bit. Oh, and from what I read about VFR stats it's supposed to have a rev limiter at 155 mph but as you can see it doesn't! :thumbsup:

 

That's in line with what mine pulled last summer. On my runs they shifted to 4th gear and wound her up...topped out around 128 mph.
*link* http://vfrworld.com/forums/fifth-generation-1998-2001/19313-dyno-run-scan.html?highlight=DYNO

I guess we can put to rest which is better K&N vs BMC as mine pulled 96.35 hp :flame:
Sorry I couldn't resist, the site needs a little spice!!

 

I would be willing to bet your bike would make at least another 5hp to 10hp
if the temp would have been in the 60-70F range. Small cc bikes and alot of heat
really hurt. The only thing that you had going for you was low humudity. So if that were my bike I would be pretty pleased . By the way how many miles on your bike? eddie

 

The only way to settle this is an official outrunning-the-po-po contest!!! :lol:

It's got 34K miles and I had the valves adjusted recently (8 of them were out of spec)

 

HAHAHA......ok, ok ya got me there Joey. I bow to the master po po runner. :biggrin:

 

I'll take that 5-10hp bet, Eddie. The humidity is more detrimental to making hp than the air temp.

 

NCB, But dont you think that 100F is a significantly high temp to run a dyno pull at? Also it has been my experience that small displacement motors are much more sensitive to high temps than larger ones. OK if you think my numbers are high and possibly they may be,what would you say would be releastic to see at say 65F with low humidity such as they had during this test? eddie

 

Hmm, I got to say I'm intriqued by this air temperature theory. I found this source: http://performancetrends.com/blog/?p=109

I'll have to wait until fall and hope there's gonna be another bike night with a dyno run

 

Standard rule number one, heat decreases the air density. A bigger problem with engines is the heat soak of the intake manifold. Heat soak happens when the the engines air charge slows down and the metal surrounding the intake absorbs this energy, slowing the actual air speed in the intake tract. This is more of a problem with cars, as the intake has actual metal to metal contact with the engine, increasing the heat transfer to the air charge. The use of rubber "insulators" between the engine and the carb or throttle body of a VFR decreases the effect of this.

Remember where the location of the airbox opening is on these bikes....it is inside the fairings. The air is already affected by the latent heat of the engine which is operating at 185 degrees, which is significantly higher than the 100 degree air temp during the dyno run. A bigger increase in hp would be seen from insulating the throttle bodies and the airbox from the heat soak effect of the engine compartment. A 35 degree drop in air temp would help, but it would not be on the order of 5-10 hp, because of where the engine is drawing the air to begin with. The latent heat from the engine is a bigger issue than the outside air temp.

I am actually working on this part of the equation right now :smile: and know that the ability to draw air into the airbox from a source other than the engine compartment is a bigger benefit to increasing hp than the outside air temp.

BTW, the dyno runs for JD's bike have been adjusted using the SAE method suggested in JD's later posts.

 

99.1 hp

75.11 degrees F, 28% humidity, 29.8 in HG

6/6/2009

 

OK, NCB - I figured if anyone would know that it would be you. I say you are the man when it comes to VFR HP and dynos. Anyway I agree with all that you said ,but what do you think about this? Yes, the engine is taking in air from an area that is approx 185F.
This is absolutly true at standstill,but when the bike is at speed dont you think that the air temp in the air box,snorkle area would be significantly lower? Have you ever taken any temp readings on you bike or elsewhere to see what the temp drop would be.?

 

Howdy vfourbear; Thanks for the data ,I presume that is from your machine?
And while I am at it, I just find it very difficult to take anyone seriously
dressed like the guy in your photo,although I must say its very creative,
cant you split your screen so that
we can see what the real you looks like?

 

No worries, Eddie, the photo isnt me, its meant as a joke, kind of like Scubalong has Jackie Chan as his avatar.......

I do get a kick out of people thinking its me, although I am pretty inked up with tats heehee I've mentioned in a few posts thats its a joke, but people keep thinking its me, so I am thinking about going to a costume shop and having an actual photo like it done.

Dont tell anyone its not me haaahaaahaa

No one takes me very seriously anyway. I dont worry about it too much, it is the interwebz after all.

Yeah, that was from my bike last month, and I threw it up there to tease Joey

Theres a pic of me on my public profile about 30 lbs ago at a restaurant with Wrestler having a beer last year, although I cant think why anyone would care what I really look like . HAAHAAA

Cheers.

 

If you notice in the picture, there is a high output blower being used during the runs.

A couple things to consider in thinking about this. The actual mass of the air in motion. The surface area of the heated surface (i.e. the engine). The actual temperature differential between the heated surface and the air mass flowing across it. Another factor is the friction of air flowing across the actual surfaces of the engine & body panels will also heat the air mass. Too many physics calculations for me, unless I really had to know exactly. The actual effects could be calculated, but dyno numbers would confirm the actual effect of the temperature differential.

I do have access to a bit of imperical information concerning this subject. I would not be working on my current path if I did not believe that having another source of air, outside the fairing/engine compartment, was beneficial.

 

Nice!!! This can be further proof that lower temps make for increased horsepower.

Also take into account global warming.

 

Let's just say for the sake of argument, you have your bike mapped at 90 degrees and 20% humidity, you take that same map and lower the temperature to 65 degress, how much extra hp would you make? not as much as you might think because the mixture would be leaned out and you wouldn't get the added benefit of being able to add more fuel and take advantage of the additional air density. Of course this brings in the open loop v. closed loop FI issue.

In practical theory, yes, cooler, more dense air makes more power, however, actually being able to utilize this increased air density is the issue.

 

What's the difference between those two?

Forgive me if I appear dense but what exactly do you mean by utilize? The bike generates more power at colder temperatures so it is gaining performance just from that.

 

Doesn't the program that prints out the curve take temp, humidity and barometric pressure into account before giving you a number? See where it says SAE 1.05..