Apex w/Boondocker Nitrous Dyno results

[stoutner]

Air Fuel ratio

We talked about air/fuel meter briefly and it was gonna be a pain in the a$$ to hook it up....and dyno time costs me money!

Look at the BSFA-B lb/hph column. He used that measurement to calculate. I'm not sure exactly how it works or exactly what it means but I think it is lb's of fuel per hour per horsepower. As you can see on the stock chart, it was almost always between .45 and .55. I sorta assumed that we wanted above .50 with the nitrous. I asked Jim and he said that I was correct.

When I did my first test with the fuel adjustment set at 53, it was below .50 at certian rpm's. In fact, the data sheet that I posted is at the 53 setting.

He asked me to adjust it up to 63 and we ran it again. At 63, we were always above .50 and horsepower was only down 1 or 2 hp throughout the range. We agreed that the "rich" setting would be much safer and well worth giving up 1 or 2 HP.

What do your air/fuel ratio's look like stock without the nitrous? Do you see any rich spots that could be leaned out?

Also, on all of my tests, the lbs/hr was around .55 - .58 when the rpm range went above 10,500. That must be designed in by Yamaha for protection up at the top rpm range.

 

[stoutner]

The torque measuement was at the crank. I noticed that when he dyno's all Yamaha's for the Snodeo shootout, all of the Yamaha torque numbers come out low. I don't know if it is accurate or if it is a problem because of the gear reduction. He does input a formula to compensate for the RPM.

 

[dynotechjim]

torque/ rpm measurement is at engine output shaft, but we punch gear reduction ratio into dyno computer to give us crank torque and RPM (HP is the same either way, just RPM and torque are different)

 

[dynotechjim]

I Reread these posts, stoutner is correct. All data is at crankshaft speed/ torque. I confused the issue by talking about torque/ rpm at reduced speed Apex output shaft taper----forget all of that, all data discussed by WayneStoutner is crankshaft numbers he was correct. The SF901 dyno is smart enough to take reduced clutch shaft speed and bump it up to crankshaft speed just like Stoutner suggested. My mistake.

 

[Beerman]

I did talk to Kyle at Boondocker about the adjustable regulator. He led me to believe that if you adjust the regulator, you would have to adjust your fuel map every time. It would be possible to "guess" an approximate range and fuel # especially if you had a wideband o2 sensor and Air/Fuel Gauge.

Hmm, that's opposite of what they explained to me. The adjustable regulator has a pressure sensor on it and is wired into the harness (that much I can verify), so the box is supposed to know how much nitrous is flowing and automatically adjust the fuel. I'll be pissed if this isn't the case since I wanted this plug-and-play.

 

[stoutner]

Beerman

Art,

I may have misunderstood his e-mail. Here is his e-mail to me:

"The kit is available…and you can use an adjustable regulator but the box will need to be reprogrammed to utilize a regulator….so that it can adjust the fuel accurately.

I would highly recommend running an o2 sensor, it will save time and money in the tuning process.. and will help you to know that your tuned properly for the best performance….even from your slightly modified stock sled.


Dynotech research will do a good job and it will help to tune your sled…you may need to make some tuning changes once it see’s real world riding but the dyno will defiantly get you close..


D and D is a great bunch of guys and I would highly recommend getting your set up from them….

Thanks


Kyle"

I think that when you adjust the regulator, the controller would automatically adjust the fuel. I know that it adjusts it when bottle temperature changes (which means pressure changes). I don't see why I would have to change my fuel setting if I added the pressure regulator since the controller already does that for pressure changes in the bottle.

After re-reading his e-mail I think that he means that I would have to have my controller programmed from boondocker for use with the pressure regulator. So, If you ordered your kit with the controller and pressure regulator, it should already be programmed to run with it.


P.S. You still would need to add a third nozzle to get the 70HP.

P.P.S. Let me know how it works...Thanks

 

[Beerman]

That's how I read that too. I'll let you know how it works if I ever get the box. I don't plan (I say that now) on using more than the stock clutching can handle without over-revving, so probably 40 or so HP is my limit. I'll have to look but I thought the two nozzels in the kit had 5 holes each, will take a look this weekend.

 

[stoutner]

Art,

Yes, The kit should come with (2) 3 hole nozzles, (2) 4 hole nozzles, and (2) 5 hole nozzles. I think the 3 hole nozzles are installed in the manifolds from the factory.

Nozzles are good for 5 HP per hole. Believe me, 50HP is plenty. It's enough to beat your buddies...

You'll never have the fastest mod sled because there is always someone with more HP, more $$$, and more time. :ORC

 

[Beerman]

Yep, been involved in drag racing for enough years to know how accurate that statement is. I'm going to start at 20 HP and dial it up a little at a time from there. My self-imposed limitation is the stock clutching and I have no doubt that you're right in that 40HP will wreck havoc on the vast majority of trail sleds and that's all that matters to me, it's just to mess around with.

Now if only the Boondocker would get the darn box built and shipped out . . . Of course there's no snow to ride in the UP for at least the next week or two.

 

[suprfst]

BSFC or base specific fuel consumption is a calculation of HP vs. fuel useage, on my old two stroke twin it needs to be above .60 to be trail safe.Four strokes do not require as much fuel to be safe.

Im not exactly shure what BSFA-B is but the numbers seem to be right in line with the BSFC numbers.

 

[HAMMER]

In general (I'm sure Jim can get more specific)

4-Stroke:

0.40 -- 0.50 BSFC

2-Stroke:

0.55 -- 0.75 BSFC

For an engine producing 200 horsepower, while guzzling 100 pounds of gasoline per hour, the equation would yield 100/200 = 0.50 BSFC. Unlike AFR (Air/Fuel ratio) readings, which only reveal the mixture, BSFC data represents the power provided per fuel unit. AFR and BSFC are not equivalent.

 

[dynotechjim]

A few years ago BSFC number on nascar engines were in mid to high .30's (lb/hphr). Today they're probably lower than that due to advances in engine design and lubrication (better efficiency and lower friction).
Because fuel consuption is so important for their form of racing, that BSFC is a huge issue.
But for sled racers looking for max performance fuel consumption takes a back seat to reliability, so even if Stoutner's sled could have made more HP with fuel leaned down (lower BSFC possibly matching NASCAR engines' numbers) using extra cheap pump or race gas to cool combustion chamber temps is good insurance. If you detonate a piston on an Apex, you're looking at maybe 40 hours to replace the piston. And detonated nitrous or turbo engines sometimes require replacement of blocks and/ or complete engine cases (unlike early bike engines, the cylinders are an inegral part of the engine blocks). So it surely pays to play it safe.
Looking back nearly 20 years in the archives on DTR you can see where two-stroke advances have changed our views on BSFC numbers. Today I don't cringe nearly as much running the dyno when we see BSFC numbers on performance sleds in the .50s on pump gas. Improvements in engine design (lower BSAC= lower BSFC) including much better engine cooling and cooling systems (like Cat's "reverse" cooling of the engines) probably is the key to sleds achieving reliability with less fuel consumption on pump gas, all this while gas octane has dropped. Up intil the mid 70s we used buy excellent leaded pump gas (260 Sunoco was about 100 octane) for 38cents a gallon!

 

[fraser.911]

i see that your from sencia falls new york, thats prolly an hour er so drive from me, i'm just curious where you went to get your sled dyno'ed???

 

[dynotechjim]

DynoTech Research
8 Apollo Dr.
Batavia, NY 14020
585-993-2777

2 miles from exit 48 I-90 (the toll collectors can hear open pipe sled engines singing on the dyno on calm days)