Topic: 2024 BMST

[Old Scrambler]

Scott............I have 127.5s............THANKS for all the help

[BomberMann650]

I'll think about a switch to turn the AFR on for the 20+seconds at max speed    

May not wanna do that.
When ZLOCK racings mechanic helped me select a wideband setup.  He did warn me about exposing a cold sensor to hot exhaust.  And/or Vice Versa.

[Old Scrambler]

Thanks for the advice, Bomber   Will likely remove the AFR to run on the salt now that I will have a dyno-test...........or..........I have room for a second battery??

[dragracer]

Thanks for the advice, Bomber   Will likely remove the AFR to run on the salt now that I will have a dyno-test...........or..........I have room for a second battery??

I vote for the 2nd battery if you have room. Nothing better than real time data.

[BomberMann650]

Thanks for the advice, Bomber   Will likely remove the AFR to run on the salt now that I will have a dyno-test...........or..........I have room for a second battery??

I vote for the 2nd battery if you have room. Nothing better than real time data.

Never did get into the data logging feature of the innovate afr meter myself.  The tech doesn't have bluetooth to connect to my phone lol

[Jerry Rxman Griffin aka MuthaF'er]

My Bad............the 125s are already in

The onboard AFR device would be nice to monitor things but it draws power from the battery and is mounted below the oil-pan perpendicular to the side of the collector...........its going to be 'in the salt' from the front tire and the wires are not part of the original wire-harness.......but I'm debating leaving it on for the 1st run on Sunday with the new 'gas' and no fairing.............the header can be changed in less than an hour.

This year I plan to shut the bike down after each run and coast to a stop on a turn-out route to be picked up by my crew with the 'chase' vehicle. Other years a rode the bike back to the pits..........so, fresh batteries for my radios are needed

I will pack radios also. Just plugged them in to charge.

[BomberMann650]

Official Countdown

[Bill/BentON Racing]

Great, get em, bro. MR12 highly oxygenated.....
But, it makes the most power, N/A I've used....
But you gotta get it out, it's not your friend
just sitting there, lol. You can definitely go up
a jet size or so...I'm already looking forward
to a new record, c'mon, lol.

[Tracksnblades1]

Great, get em, bro. MR12 highly oxygenated.....
But, it makes the most power, N/A I've used....
But you gotta get it out, it's not your friend
just sitting there, lol. You can definitely go up
a jet size or so...I'm already looking forward
to a new record, c'mon, lol.

With a stoichiometric of 12.8***for the MR12, what af did you find the best power and torque at..?

[Don R]

 The second battery is a plus. I did that on my dragster to keep the racepak working going down track. I had a charging issue caused by increased load of the efi that took the car below 11 volts. That's where my data recorder turns itself off.
  Does the o2 sensor have an electric heater in it? My autometer wide band o2 wants to get hot before it sees exhaust.

[scottly]

New Info: I have a dyno appointment on Tuesday

More new info.......I will use VP MR12 for the dyno-tests and then plan to run that same gas in the FUEL classes before I switch to Sonoco EXO2 for GAS classes.

What class/fuel did you run when you went 148MPH? That is the fuel you should run on the dyno. Switching to a fuel class is a whole different thing!
Besides checking the jetting, the other thing to look at on the dyno is the peak HP RPM, as it may have changed with the new cam. Don't rev the engine past 10K this time.
I believe you may have been within 1 tooth less on the rear sprocket from breaking 150 the last time. After breaking that record, then go for a new record with fuel.

[scottly]

With a stoichiometric of 12.8***for the MR12, what af did you find the best power and torque at..?

I tried asking VP several years ago what the max power AFR should be for one of their fuels, but never got a good answer. I sent the following message to Sunoco today:
"The stoichiometric AFR for pump gas is around 14.7, but for maximum power the AFR is in the range of 12.8 to 13.2. If the stoichiometric of EX02 is 13.2, what should the maximum power AFR be?"
I got the following response:
"Great question.  The actual answer is easy, though it can get complicated…

 

A good rule of thumb is that maximum power can be obtained using an A/F mixture that is about 85% of stoichiometry.  So for EXO2, 85% of 13.2 is 11.2.

 

It gets complicated because almost all aftermarket devices measuring A/F ratios ASSUME a stoichiometric A/F ratio of 14.7:1, so they don’t report actual A/Fs.  How can you tell?  Well, if your device asks you to enter your fuel’s stoichiometric A/F ratio as part of a set-up or calibration procedure, it’s probably going to report actual A/F ratios when in use.  If your device does not require a stoichiometric A/F ratio to be entered, it cannot report actual A/F ratios when in use.  Sounds weird, but we run into this problem all the time.

 

There is a solution, albeit a patch of sorts.  If your A/F monitoring device does not have a provision to enter the fuel’s stoichiometric A/F ratio, it’s probably assuming a baseline of 14.7:1">14.7:1 (which is not really accurate either but that’s another story), so just tune for 85% of 14.7 which is about 12.5.  For power adder applications and when using oxygenated fuels like EXO2, you may find max power at A/Fs even richer than that.

 

Thanks for the inquiry – holler back if you need more info.

 

Mike / Sunoco Performance Products"

[Old Scrambler]

Thanks, Bill............have funnels and hoses to handle the 'quick drain' aspect.

Tracks.........I have never had a data-logger but pay close attention to inner-porcilin plug color.

Ron.......Yes, the Innovative unit needs to be heated for 10-15 seconds before running the motor.

Scott.......MR12 is still gasoline but not available at the salt........so it is considered fuel by the rules-writers. The boss at the local Honda dealer is supporting his son on the AMA Pro-MX circuit and tells me he has learned a few things about MR12.........enough that he stocks it at the dealership. He will be running the dyno and will use the bung on my header to gather AFR data.....hoping for a GOOD printout My dyno run is scheduled for 4PM.

[Old Scrambler]

Thanks for the info.........  13.2...........14.7............11.5............When a small cloud passes over the sun while measuring AFR on the salt, the effective altitude can go down by 1000-ft. or more.

The gas/fuel advisors are usually referring to fuel-injected AFRs ..........Carburetors will tend to have varying AFRs as you go through the rev-range. When I ran Best on 110 gas I was at the low range of what others thought was best.

I will listen carefully to the dyno-tech. Thankfully, my motor is not a super high-compression 'bomb' so I have some wiggle room to try and fine tune if not good out of the trailer. BTW.....this is a fast-burn gasoline and I've been advised to widden the gaps on my plugs.

[scottly]

MR12 max power AFR should be 10.94:1, while for Sunoco EX02 it's slightly different at 11.2:1, per the .85% rule. Don't know about widening spark plug gaps, but fast-burn fuel means you usually need less spark advance. Remember, DA is for aircraft pilots, as it deals with not only reduced power, but with reduced lift from the thinner air.
Will be waiting anxiously for the printout!

[Tracksnblades1]

MR12 max power AFR should be 10.94:1, while for Sunoco EX02 it's slightly different at 11.2:1, per the .85% rule. Don't know about widening spark plug gaps, but fast-burn fuel means you usually need less spark advance. Remember, DA is for aircraft pilots, as it deals with not only reduced power, but with reduced lift from the thinner air.
Will be waiting anxiously for the printout!

Good info and good to know the 85% rule extends to fuels other than ones with the ideal 14.7 : 1 stoichiometric mixture blend..

I’m pretty sure VP can provide the average flame front burn speed per application…

[Old Scrambler]

Dyno test is over...............and after 4 jet-changes............POWER

The graph will be emailed to me in the AM. Had issues with a bad plug on #2 and ignition timing is now at 44* advanced..........but all is good and it ran in the mid-10s......smooth and steady power that is somewhat MORE than ever Previous was 79 RWHP tested at 700-ft. Now I have more power at 4200-ft. I will email the graph to Scott so he can post in this thread.

[scottly]

44* advanced!?? What jet sizes did you end up with?? Need my email again?

[scottly]

[Tracksnblades1]

Dyno test is over...............and after 4 jet-changes............POWER

The graph will be emailed to me in the AM. Had issues with a bad plug on #2 and ignition timing is now at 44* advanced..........but all is good and it ran in the mid-10s......smooth and steady power that is somewhat MORE than ever Previous was 79 RWHP tested at 700-ft. Now I have more power at 4200-ft. I will email the graph to Scott so he can post in this thread.

44* 😳  sounds like an old 327 sbc with 10.25:1’s pistons down in the hole 0.020 that someone put a felpro blue 0.038 head gasket on that would fit up to 4.125 + 0.030 over bore…. Is it the fuel or just the head and squish/quench..?
Glad you’re making more power… “Scotty, I have to have More Power.!” 😁

[scottly]

44* 😳  sounds like an old 327 sbc with 10.25:1’s pistons down in the hole 0.020 that someone put a felpro blue 0.038 head gasket on that would fit up to 4.125 + 0.030 over bore…. Is it the fuel or just the head and squish/quench..?

We are not discussing a small block Chevy, we are talking about a project that a bunch of us have been involved with for some years now. Please try to stay on topic.

[scottly]

Wow, it was over two years ago when Dennis had the CBR on my dyno!!!

[Jerry Rxman Griffin aka MuthaF'er]

44* 😳  sounds like an old 327 sbc with 10.25:1’s pistons down in the hole 0.020 that someone put a felpro blue 0.038 head gasket on that would fit up to 4.125 + 0.030 over bore…. Is it the fuel or just the head and squish/quench..?

We are not discussing a small block Chevy, we are talking about a project that a bunch of us have been involved with for some years now. Please try to stay on topic.

Oh, it's not an RC327 cam? Got me for a second

[Old Scrambler]

I'm still waiting for the graf....................one run showed 81 and another showed 82-HP at the rear wheel. I don't recall the torque and at what RPM the peaks were at.

I ended up with 117.5 jets and the tech told me I was likely running quite rich on the 110 for maximum power. He suggested larger pilot jets would help at idle and mid-range..........but would also help on the top-end and might allow one size smaller mains to get the AFR under 12:1.  The graf will say for sure, but I think AFR is now 12.3:1

So I'm ready to start travelling in the AM...........

[scottly]

What was the fuel when you were at my place? It was way lean with 120 jets. What's the delay on the graph? Do you need to call them and remind them before they close for the day?