Advancement of fuel delivery?

[DonWG]

Sunday the race was cancelled due to high winds, which led to fires all over California. I packed up the car and when I got back to the shop, decided to do some tuning, since the wind was not bad at all at the shop. The car was still on methanol and I needed to work on the return road tuneup (light cruising up to 2800 rpm). After working on that in front of the shop, I pulled the car into the shop and started to play with the tuneup at converter stall on the transbrake.

After studying some recent datalogs and doing some experimenting I found that this engine really likes the a/f ratio under boost that I had assumed was too rich. My readout is set for gasoline and I guess I was thinking too much of what good a/f numbers would be for gasoline. I was assuming those lambda values would also work for methanol. I was wrong. During recent track testing, I was starting to realize that as I tried to lean the a/f ratio under boost to my target of 11.3 to one, my mph started to drop off or at the least was not getting any better. I always felt that as I leaned toward 11.3 the mph should increase. A sure sign that HP was coming up. It didn't.

In the garage, as an experiment, I setup the a/f table to target 12.4 at 2440 rpm, which is converter stall at 0 boost, and ramped the target a/f ratio to 10.2 to one by 135 kPa boost. The results of the test was interesting. After going WOT, the rpm would go to 2440 rpm as usual, but then slowly climbed to 3400 rpm, which is when I got out of the throttle. Not sure how high it would have continued to go. As a check, I went back to the a/f table and set the target a/f to 12.4 at converter stall at 0 boost, ramping it to a different value at 135 kPa. I used 12.4 for this test. The result was, the engine rpm stalled at 2440 rpm and did not increase as before. I couldn't go back and do a retest because I ran out of methanol. Grrr. More testing to continue. What would going richer still bring?

After getting this result I decided to look up some old notes that I had taken on safe best power and rich best power for gasoline versus methanol.

Safe best power for methanol is 5.5 to one.
Rich best power for methanol is 4.5 to one.

5.5 methanol = .85 lambda = 12.48 gasoline.
4.5 methanol = .70 lambda = 10.21 gasoline.

I guess it's a good idea to dig up old notes and read over them every once in awhile.

[DonWG]

Finally got the base fuel map finished. Settled in with a .73 to .74 lambda @ WOT. By the end of the day, I started adding the auxiliary fuel into the tuneup. Datalog looks good except for that aux fuel activation point. I'm getting that pesky lean spot before the fuel stream from the nozzles kick in. The map is increasing so quickly that the boost is pretty up there while this lean spot is still recovering. I'm working with keeping the electronic injectors on high pw through this transition, but it isn't helping much so far and I can only carry on this overlap for so long. I might end up having to use the nitrous fuel delay box to help supply extra fuel during this transition point. Maybe I should tune in the nitrous system first, without the aux fuel (limiting my rpm to 6000 rpm) and dial in the fuel delay to give me an extra rich spot right at the aux fuel transition point. Then throw the aux fuel into the tuneup. Yikes. What a mess.

[DonWG]

Well! Today was very interesting. I've read that methanol has a very rich burn limit. I just didn't know how far. From the results of the datalogs over the weekend, I decided to have the aux fuel come on and not throttle back the electronic injectors. Just let the injectors run at 85% duty cycle for the whole run and have the constant flow injectors come on at 16 psi. The dang thing ran about the same as it had when I was trying to throttle the injectors back over 50% after 16 psi. This throws a monkey wrench into my fuel strategy. I have to admit, it makes a few things easier now.

The lean spike was still there. Even without trying to throttle the injectors back. This is the conclusion I've come up with for this event. The volume of air that is between the aux fuel solenoid and the orificed nozzles is pushed out of the nozzles after the fuel solenoid has been activated with enough force to affect the air/fuel mixture. Momentarily, instead of injecting fuel, the nozzles are injecting air down the ports. A form of forced induction in itself. What I'm going to try to do to combat this is to reconstruct my fuel map so that I have enough range on the VE table to step up the pw during the window when the aux fuel is activated. How much % I'm going to need is the big question. If I can get the mixture right at this point, it should feel like a mild dose of nitrous right at 16 psi. So the regular nos system will turn off at 16 psi with a fraction of a second of fuel side turn off delay and the aux will turn on at 16 psi with a fraction of a second of increased pw to add to the short time of injected air from the constant flow nozzles. At least now, I won't have to worry about how much to throttle back the electronic injectors.

I feel like I'm building Frankenstein.

[DonWG]

It worked! Last night I did some test launches in front of the shop and the extra pulse width at the time of aux activation did the trick. There is still a slight and short lean spike toward the tail end of the transition, but no more lean pop and drastic engine rpm drop. RPM and map rise through the transition is smooth and rock solid. The slope of the rpm and map rise does actually increase at the transition point. This could be a sign that there is more room to richen the mixture in the cells before aux activation. But, that's the region that the nitrous is on and the nitrous system is set a tad bit on the rich side. More testing. What's new.
Looks good to go for adding nitrous for a better launch to the mix. With the nitrous system's fuel turn off delay, I may be able to work the duration of the time delay to further lower the slight lean spike that's still there in the datalog.

The fuel map ended up being sloped for 1050 hp (zero VE correction) with 312 kPa as the upper limit. Most of the cells of the VE table from 16 psi upwards to 312 kPa were topped to the max at +50%. Quite a bit of cells at the upper rpm and map corner had to be reduced so that an 85% duty cycle on the electronic injectors would not be surpassed. That's why the slight lean spike still in the datalog. Just ran out of extra duty cycle towards the end of the transition period.

The next thing to work out is going to be at what point I activate the nos during the countdown on the tree. Too early will lead to the need of the wheelie bars.

Oh, what fun!

[DonWG]

Testing up to this point has reached 28 psi. Sure wish I had some of that old CR back.

[DonWG]

The other day I realized something. If it proves that the engine starts to lean out at max rpm, I can increase the delay on the nos fuel solenoid to keep it on until the end of the run. That way I'll have three sources for fuel going on. The 160 lb/hr electronic injectors, the 80 lb/hr constant flow nozzles and 43 lb/hr from the fuel side of the nos system. Dang!
I may have to up the dial on the pump booster.

[J-B Racing]

Originally Posted by DonWG

The other day I realized something. If it proves that the engine starts to lean out at max rpm, I can increase the delay on the nos fuel solenoid to keep it on until the end of the run. That way I'll have three sources for fuel going on. The 160 lb/hr electronic injectors, the 80 lb/hr constant flow nozzles and 43 lb/hr from the fuel side of the nos system. Dang!
I may have to up the dial on the pump booster.

You are a Madd Scientist Don..
Interesting stuff...

[DonWG]

I'm glad you find it interesting. It's a trip to play around with the fueling and actually have something finally work out. I know this has got to be a very boring thread for the vast majority out there, but for some true blue tuners I'm sure there is something to pick out of all this or maybe use to confirm their own work. Today I thought about an application for some of this for the simple street/strip application. More later.

[DonWG]

Imagine this. A typical GN installs a nos system to help quicken spoolup. Just a 50 hp system, single nozzle will do. The nitrous turns off at 16 psi, but the fuel side stays on. The fuel used with the nitrous system is methanol. Starting to sound familiar?

The advantage of such a setup:

Use a large turbo if you wish, without the worry of turbo lag. Imagine no turbo lag. Wow.

Use a stock torque converter, if you wish. No more worries about matching the perfect torque converter to your setup. Take it from me. It is so nice not to have to worry about whether the torque converter is just right or not.

Use pump gas and get the performance you would expect with the use of alcohol injection with high boost.

Got some of you thinking yet?

[DonWG]

Originally Posted by DonWG

The other day I realized something. If it proves that the engine starts to lean out at max rpm, I can increase the delay on the nos fuel solenoid to keep it on until the end of the run. That way I'll have three sources for fuel going on. The 160 lb/hr electronic injectors, the 80 lb/hr constant flow nozzles and 43 lb/hr from the fuel side of the nos system. Dang!
I may have to up the dial on the pump booster.

The nitrous system fuel side might turn out to be a useful tool in determining how much I need to increase the orifice size of the constant flow nozzles. Before I think about changing the nozzle sizes, I need to work up to the max boost level for this engine. The way the engine is responding to the present boost levels as compared to the last engine configuration, it's looking like 32 will be a real target.

Alcohol likes compression. If you're low on your static CR, you need to plan on using a lot of boost to make up for it. The problem that fights you with that is you're having to heat the intake charge more with the higher boost. A give and take situation.

[Chevota]

Originally Posted by DonWG

The nitrous system fuel side might turn out to be a useful tool in determining how much I need to increase the orifice size of the constant flow nozzles. Before I think about changing the nozzle sizes, I need to work up to the max boost level for this engine. The way the engine is responding to the present boost levels as compared to the last engine configuration, it's looking like 32 will be a real target.

Alcohol likes compression. If you're low on your static CR, you need to plan on using a lot of boost to make up for it. The problem that fights you with that is you're having to heat the intake charge more with the higher boost. A give and take situation.

Looking forward to comparing fuel strategies with you this weekend at the WCN!

Scott Wile

[DonWG]

Originally Posted by Chevota

Looking forward to comparing fuel strategies with you this weekend at the WCN!

Scott Wile

Me too Scott. Should be fun.

[DonWG]

This last weekend was a milestone. I have finally reached a point with the tuneup that I can consider a good, rock solid base tuneup. I finally have something that I can start tweaking to squeeze out a little more.

Areas that have not even been explored yet:

Ignition timing table. It's still the start up table.
Wastegate spring tension to control the slope or sharpness of the boost curve just before max.
Room for more fueling at the upper rpm range. Forcing the need for larger mechanical injection nozzles.
The option to continue the nitrous system's fuel side for the duration of the run, even after the nitrous gas has been shut down.
The option to continue the nitrous injection system as a whole for the duration of the run. Although, I'll think long and hard on this one, because of the large shot I'm using.
More boost! Of course! I think the turbo is about lunged out though.

I had always referred to this engine as a detuned version of the previous engine build. I now have to say that this engine build is superior to the previous engine, all things considered. I had always calculated that if I were to be able to pump 30 psi out of the T76 I'm using, this engine would at least match the previous engine's performance level at just 22 psi. I was right on. Actually, the ET is better by a tenth. I'm feeling much more relaxed now that things are starting to fall into place. And might I add, in a big way. As you can probably tell, I'm a happy guy right now. It is so rewarding to be visualizing how a certain combination could actually work, have the idea be so contrary to popular opinion in so many areas in not just the engine, but other areas of the powertrain too, plug away at it for years and then have it proven to be correct. Wow. I wonder what my critics are talking about now.

And to think that I just stumbled onto this tuneup over the weekend and clicked off a new best for the car. What's still in it?

The write up on the car's new best is in the time slip section.

[DonWG]

Increased density before the turbo means increased density after the turbo with the same pressure ratio. A good method to get more HP range out of a relatively small turbo. I think I see, Scott. Nice.

[J-B Racing]

Don
I just want to say that you have a Clean and well organized Machine.
I envy your work, and the time you take to get the most of what you have.
I always read your posts and admire all the time your put into your car.
I just wish I had that time. Maybe one day...


"Look Forward"


JB

[DonWG]

Originally Posted by J-B Racing

Don
I just want to say that you have a Clean and well organized Machine.
I envy your work, and the time you take to get the most of what you have.
I always read your posts and admire all the time your put into your car.
I just wish I had that time. Maybe one day...


"Look Forward"


JB

Thanks for the kind words JB. It makes me feel good when someone can truly appreciate the effort made. I hope you find the time to move forward with your projects. Small steps. Small steps.

[Hot Air]

Donnie,
Way to go! Interesting reading to say the least. Keep it up.
Conrad