This is going to be common knowledge and as expected to most of you. I thought I would share some real-world results of adding more water/meth without tuning for it. Keep in mind that I had a size 6 nozzle and was tuned for it then added a size 8 with no tuning. Meth is on at 4 psi full on no progressive ramp. I did not notice any bogging.

Opening day at the local small town drag strip first pass. Car is a 2004 Pontiac GTO with a race weight of just over 3900 lbs and independent rear suspension. Heavy car with IRS terrible combination for drag racing. Fuel is 50% ethanol and the meth is a pieced together setup I did using windshield washer fluid with 3 bottles of heet in it.

Sitting at the line staged idling like I would in traffic at a stop light. Jumped into it about half throttle and rolled into it from there. Clean pass for data essentially my first dyno pull after the changes.



Holy cow my mph was way down from prior which was last year. I had added a bit more boost which was tuned for with the previous 6 nozzle but hadn't made a pass at that boost level yet. That along with the larger meth nozzle I was expecting to trap higher not way lower.

Screen shot from the run showing my AFR. 10.15 holy fat pig batman.


It was opening day with well over 100 cars and there was a massive full track oil down after this run. They also had some issues with rubber coming up from the surface. We sat in the stands waiting for over an hour before the lanes were reopened. I took some fuel out of the tune as my only change then got back in line. Another oil down delayed the action further.

On my next pass The AFR was closer to 10.8 and I picked up 3 mph and trapped over 113 mph with no other changes to the tune. I made another change to take some more fuel out and also raised the 1-2 shift a bit. I was shifting to 2nd at 6850 rpm and 3rd at 7300 so I raised the 1-2 up to 7000 rpm.




After the second pass the wife and I decided to drive her home as it was a long day. We have time off so we can hit each of the next several test and tunes if needed to get her dialed in. I should be trapping close to 120 mph when it's dialed. Once the AFR is dialed in I will see how the plugs look and determine if I can add any more timing. Right now, they show that I could obviously but it's so rich I need to get the AFR closer before I can make an accurate determination.

Check out the IAT. It was a cool day about 67 degrees but even with the metal btr intake sitting in a lot of stop and go in the lanes for a very long time no ect or iat issues at all. Of course, this was driven to and from the track it's nearly being driven daily currently.

With the tune dialed and getting more aggressive on the launch 5.9x consistently is the goal. Stock ls3 block, stock ls1 heads, btr equalizer intake, ls7 lifters, ws6store rockers, cam motion custom cam, stock throttle body, forged rods/pistons. Long block has been together for over 5 years now. Ls9 gaskets with ARP head studs.

 

 

Your post reminds me of some old dyno tuning I was doing on the original rear mount kit on my 2004 GTO. Running 50/50 produced a VERY noticeable bog when the meth spray activated. I don't remember the nozzle size on that Devil's own kit, but I was spraying enough to bandaid a weak fuel system. I tried to find a sheet with 100% meth, but I only found ones from the 50/50 mix.

 

Even though I was down a bunch of mph/power I felt no bogging or any change by seat of the pants. I feel that at higher power levels seat of the pants is not a good measuring tool at all.

 

Pretty small volume of fluid for the motor size and amount of air you are flowing. Shows how much water limits the kits. If you were injecting 100% meth, a 2gph change in nozzle size would likely not even be noticeable. You could max the pump out easily at 30gph+ and get larger gains in charge temp reduction and additional octane. Then again… if ya don’t need it, no reason to complicate things w upgraded lines/fittings/etc. For simplicity I spray 8gph on my non intercooled E85 5.3 with 50/50. Already hit my goal, no reason to push harder with more meth.

Spray 100% meth @12gph on my supercharged wave runner with 91 octane. 1.5 liter that turns 8900rpm and makes 15lbs. It picks up RPM and boost on the meth by retaining an NA style timing map. 4mph difference with vs without on the water. Quite a bit of meth flow for such a tiny motor. Would be like hitting an LS3 with 50gph. It absolutely loves it.

 

If you're running upwards of 20 lbs. of boost, why have the meth come on at 4lbs.?
My plan was to have mine come on at 10lbs. or so, perhaps less but not more because my thought process is that pump fuel is perfectly fine at 10 lbs. and would give enough time for the meth to get rolling by the time it was really needed up into the 14+ lbs. range and beyond.
Is my thinking wrong on this?

 

I’m on 50 percent ethanol so I don’t even “need” the meth. I was maxed on my magnafuel 4303 but ok I just added the meth to take some pressure off the fuel system. Once I used it I liked it so I added more. I’m right at 20 psi at 7200-7300 rpm. I want it coming on as early as possible and it doesn’t bog so I just need to dialin the tune to get the afr back to 11.5 then I’ll be good. Rhe sooner it’s on the more cooling I get.

 

Ah I see, so if you're not after the cooling effects like I am, just the octane benefits, I can probably bring it later.

 

Just don’t want it coming on during the launch or it will really bog you down.

 

I use it for both. My opinion is bring it in as soon as you can as long as it doesn’t cause a bog effect. Since I’m only using a size 8 nozzle I can bring it all in at 4 psi with no ramp I just need to finish dialing in the tune to get the afr right. .

 

At this point I'm just sitting there idling with one foot on the brake and one foot on the gas then stab it about half throttle and roll into it as I feel traction. I come into boost immediately as soon as I get on the gas and don't have any bogging. I could see this changing if I was building boost on the line and launching properly. As I get farther along, I will adjust how I use the meth if necessary. I think I had to much tire pressure also at 18 in the slicks so I will start with 16 psi at this weekend's test and tune if the weather allows.

 

Sammy?

 

Sorry I missed the joke ?

 

Sammy Hagar "I can't drive 55".

 

lol...

 

I think part of my issue was in addition to the bigger nozzle I had forgotten that I mixed my methanol content to a little higher percentage as well. Hopefully the weather cooperates so I can get back to the track tomorrow night to see what she can do with rhe correct afr and then possibly more timing.

 

You can damn near garden hose pure meth in without losing significant power from being too rich. That water mix, however....

edit-- I wish I could find those old dyno sheets from switching to pure meth, but they probably got tossed out years ago. I only kept ones that showed something unusual, and they showed no noticeable bog at all.

 

Wanna say those “full boost” Youtube guys debunked that w back to back dyno pulls. They def lost a healthy amount of power until they leaned the AFR back out within reason on 100% meth.

My waverunner was tuned to 12.5:1 AFR and def lost lots of power with 12gph of 100% meth kicking on. Had to pull a ton of fuel to get her dialed in. 50/50 is a different animal. Not even in the same category IMO. Any water in the mix drowns out spark at decent volumes. More of a CC cooler to be run at baby volumes. While methanol is aux fueling w no real limit.

 

To be fair, 12 gph of meth on a waverunner motor might be more akin to firehosing it in, lol. Even going down to where a gas-scale wideband is showing 10.5:1 rich should not drop too much power, and I would consider that pig rich hosing fuel in. Then again, he is using around an e50 mix to begin with, and I have never experimented with meth on a motor with anything over e10 for a base fuel. That could make a difference I have not even thought about.

 

Yea enough meth to supplement about 38hp on a 275hp ski. Or 14% of my total fueling. Not tooo crazy volume wise. 30% plus is where huge gains come in.

Think the math works out to this approximately.

One gallon of methanol weighs 6.3 lbs so a BSFC of 2 equates to .0053 GPM.

Multiply .0053 into the amount of HP you are trying to make with 100% meth. That will give you the approximate GPM required. Multiply that by 60 for gph.

So when you hear guys talking about spraying 8gph of 50/50 (4gph worth of methanol) Its only supplementing 12-13hp w methanol. Or 2% of a 600hp setup.... so not doing a whole lot. Also shouldn't require much tuning change.

Also gotta factor in 50/50 blends aren't 50/50 by weight, they are 50/50 by volume. So they aren't super accurate and are usually less than 50% meth. (some a lot less)





Here was the old video I was thinking. Pretty sure they did straight meth and mixes? Don't 100% recall. I can't watch it at work.