Advancement of fuel delivery?

[Alky V6]

Donnie, whats the hp rating on that turbo your using now?

I'm told by the supplier, 1650hp.

Maximum PR is 5.5 @ 125 lbs/min. Fits the 224 cid nicely.
Maximum lbs/min is 165 @ 3.7 PR. 88,000 wheel speed.
Maximum compressor efficiency is at 2.8 PR @ 120 lbs/min (78%). Again, fits my hp target of 1230 nicely. Sweet!

 

[Alky V6]

It's been awhile since I've updated this thread. The last outing with the car was the one which netted the 1.66 60 foot time. On the next pass attempt, there was a small intake backfire experienced at the starting line. The run was aborted. We towed the car back to the pits and found that the number 6 cylinder spark plug had lost the porcelain during the previous run. The engine has since been pulled and checked out. Pieces of porcelain got between the valves and seats causing the valves to hang open slightly. That's what caused the small intake backfire when the nitrous activated at the launch during the last pass attempt.
Damage to the engine was slight. I had to re-ring the engine, brush the cylinders with a hone, pick embedded porcelain out of the combustion chamber and piston top, smooth the nicks in same, and replace the intake and exhaust valve in #6 cylinder. The number 3 main bearing also showed signs of overloading related to #6 cylinder. All other bearings were fine.
Why did number 6 loose the porcelain? The ground electrode was also burned back. Number 6 obviously went into preignition. I checked out the fuel system and nothing was plugged. All the other spark plugs looked perfect. I do recall that engine temp was at the upper limit at the start of the suspect run. For the a/f mixture I was running, the engine might have been too hot. The spark plug heat range was not the coldest either. The starter came up to me later and let me know that he noticed a white poof from my exhaust on the top end of the last run. So the preignition happened on the top end.

The long block is back together and the intake manifold is going through some upgrading. I'm adding more flange, runner to plenum fasteners in preparation for higher boost numbers. It's time. I'm also upgrading the fuel system. Removing any materials that may be corrosion factors and adding another fuel pump. Fuel mixtures and ignition timing will be adjusted.

Here's a link to the intake manifold upgrading:
http://www.turbobuick.com/forums/fabrication-no-solicitation/275644-intake-manifolds.html

 

[Alky V6]

Today I started testing with the 300hp nitrous shot. Some simple, short launches out in front of the shop. I have some good data logs to study. It definitely kicked that 91mm in the a**. New territory in the fuel map is being explored. I would even venture to say that the nitrous shot could be larger. I'll post more after I study the datalogs.

Nitrous bottle temp was only at 800 to 850F.

 

[charlief1]

You must have gotten the QA1 set up on then. Hows the car feel now on launch? Better or still light in the rear?

 

[Alky V6]

You must have gotten the QA1 set up on then. Hows the car feel now on launch? Better or still light in the rear?

The car feels solid and true. I haven't weighed the corners yet. I setup the ride heights with the left front 1/16" higher than the right front. Roll bar with the slightest preload favoring the right rear. I took some pics of the left front coil spring adjustment compared to the right front coil spring adjustment just to get that 1/16" difference in ride height. Quite a bit.

The spool up path through the fuel table is into new territory. I'm finding a good mixture in some parts while too lean in others. That caused a not so smooth rpm rise, while the map rise seemed fairly smooth. I also was using a nitrous retard of 30 degrees which netted me close to zero degrees advance. After I get the fueling more on target, I'll start increasing the timing to see what I'm missing out on.

 

[charlief1]

Get it weighed and then vid the launch. Just remember the rear trick I sent you if it doesn't get better. You should even improve your 60' some with it.

 

[Alky V6]

Playing with the fuel map in the area of the initial nitrous hit, I was able to smooth out the rpm rise up to converter stall. It sounds bitchin!

New converter stall on the 300hp nitrous hit is 3820 rpm. Achieved in .53 seconds.

Initially, the transbrake timer will be set to release at .34 seconds on the nitrous hit. That will be a stall speed of about 3300 to 3400 rpm when the car comes off the line. It will produce a mild launch. Small steps. Small steps.

Converter stall on the motor only, at 96 kPa manifold pressure is 2420 rpm.

There is a very interesting characteristic I learned about nitrous fueling at the start of the hit that scared the stuffing out of me. I'm starting to understand how intakes get blown apart at the starting line. During my playing around with the fueling at the start of the hit, I was going for the next level to top the perfectly smooth rpm rise to 3820 rpm stall on the converter. The rpm rose quicker on this particular test and was at a little over 3500 rpm when a couple nasty intake backfires occurred. My home-made intake pop-off valve saved me again! The datalog showed that the kPa value of the backfires were actually pretty mild. Still, It scared the holy stuffing out of me and I quickly decided to settle for the smooth 3820 stall test and quickly added in a couple more degrees of ign retard. The retard is now at 27 degrees on the hit, netting 5 to 6 degrees of advance at the initial hit of the nitrous.

The intake backfires occurred as I attempted to "richen" the a/f ratio at the initial hit of the nitrous. Is that interesting or what.

 

[Alky V6]

Map at 3820 stall on the nitrous read 98 kPa. There was no boost assistance. It was all nitrous.
Boost starts building at about 4,000 rpm. Keep in mind this is a 224 cid engine spooling up a 91mm.
The a/f ratio at 4,000 rpm appears to be very critical inorder to get the smoothest and quickest boost rise. Further tuning is going to require launch testing with a properly prepped track.

 

[Alky V6]

The intake backfires occurred as I attempted to "richen" the a/f ratio at the initial hit of the nitrous. Is that interesting or what.

It seems I was reaching a combustion temperature and cylinder pressure threshold for the fuel for that particular mixture strength. I feel that leaner or richer of this particular threshold is OK. In either case, combustion temps are down. Since I was running out of room in my fuel map to add anymore fuel, I decided to lean back down away from this preignition threshold. This causes a slower rise in rpm on the hit, but it's safer and it allows time for the fuel side of the nitrous system to catch up and start controlling combustion temps.

On this failed test, this occurred .35 seconds into the hit. That is a fair amount of rpm rise in that short of a time span. Too fast for the fuel side of the nitrous system to catch up and get combustion temps under control. If the nitrous fuel side didn't have so far to travel after the activation of the solenoid, it would be a completely different story.

With the 3820 tune, the engine rpm reaches 3500+ rpm in a little more than .5 seconds. A little more than 3300 in .34 seconds.

Bottle pressure with this last few series of tests was 1050 to 1100 psi. This is a worst case scenario working pressure.

Back to setting up the suspension for the upcoming launch tests, although they will start out as being mild launches.

 

[Alky V6]

I think I'm going increase the length of hose from the nitrous solenoid to the distribution block to hopefully delay the time it takes for the nitrous gas to get to the nozzles. I need to create a delay of .16 seconds, or at least, take a big bite out of the nitrous/fuel feed stagger that's occurring.

 

[Dusty Bradford]

The retard is now at 27 degrees on the hit, netting 5 to 6 degrees of advance at the initial hit of the nitrous.

The intake backfires occurred as I attempted to "richen" the a/f ratio at the initial hit of the nitrous. Is that interesting or what.

Why so much nitrous and so low timing? I can't possibly imagine needing 300hp worth of n2o to spool a turbo. The backfires can also be from excessively retarded timing that you need with the large shot of n2o. More timing will help make the engine much more responsive and should reduce the need for that large of a hit.

Most nitrous backfires that blow the hoodscoops off the cars is from excessive timing retard while on the transbrake.

 

[Alky V6]

Why so much nitrous and so low timing? I can't possibly imagine needing 300hp worth of n2o to spool a turbo. The backfires can also be from excessively retarded timing that you need with the large shot of n2o. More timing will help make the engine much more responsive and should reduce the need for that large of a hit.

Most nitrous backfires that blow the hoodscoops off the cars is from excessive timing retard while on the transbrake.

Keep in mind that I'm pairing nitrous with alcohol. A 300 shot on gasoline is not the same as a 300 shot on alcohol. You kinda have to learn to ignore the 300 number with my setup. It's the resulting spoolup that's important.

What would you think a safe retard would be with a 300 shot on alcohol with a tight torque converter? I'm only trying to start out safe with this 300 shot and work up on the timing, but if you say that excessive retard can be just as bad, I'd like to hear more advice. Thanks Dusty.

I did a total of 8 tests. Only the last one gave me a backfire, and only after richening the initial hit area in the map. I was trying to lessen a lean spike that was occurring for a duration of .16 seconds on initial hit of the system that was showing up on the datalog. In the beginning, there were also dips in the rpm rise after the initial lean spike. Rpm rise during the first .16 seconds was actually quite good up to 3300 rpm. The lean spike would start to recover after that point and rpm rise looked like a roller coaster up to 4000 rpm. As I richen the 2800-3800 rpm spread, the roller coaster smoothed out more and more until I reached a point where the rise was perfectly smooth and the sound of the engine was even noticeably 'bitchin'. Since I was now up to 3820 stall at about .55 seconds, I thought I'd try to hit the magic 4000 mark. Understand that up to this point adding more fuel to that 2800 to 3800 rpm spread was working big magic for me. I thought, heck 4% more fuel throughout that rpm spread just might be the ticket to move it up to a 4000 stall in .5 to .6 seconds.

25 degrees retard was what was used for all but I think the first test, which was 30 degrees retard. During the first test with the 30 degrees of retard, I noticed a rather large rpm dip on initial hit. 2410 to 2332 rpm. It recovered in less than .1 seconds. When I stepped up the 25 degrees retard, the dip was still there. The same degree of dip and the same duration. I decided to leave the retard there until I thought I had the fueling more under control. The only thing I changed throughout most of the tests was small increases in fueling in the map at the initial hit area from 2800 to 3800 rpm, 3 to 4% at a time. kPa staying between 95 to 97 kPa through the initial hit, up to just before 4,000 rpm. kPa actually dropped to a small degree on initial hit, 1 to 2 kPa. The engine creating slightly better vacuum from the increase in power from the nitrous. The turbo caught up to the engine by 3587 rpm reading 0 vacuum, 0 boost. 98 kPa with my system. First tiny sign of boost at 3804 rpm, 99 kPa.

This is some data from the test before the 3820 test and the 3820 test.

datalog#17n (test before the 3820 test)
rpm at .529 sec. into the hit: 3690

datalog#17o (3820 test)
rpm at .549 sec. into the hit: 3804
rpm at .496 sec. into the hit: 3757

So you can see that some big power was being gained from just small fueling increases in that 2800 to 3800 rpm range. It was too tempting to see what another 3 to 4 percent of fueling might net.

What I really think happened was, as I increased fueling, engine power increased and rpm rise quickened, putting the engine on the torque converter sooner and harder with each step up of fueling. The engine was not recovering fast enough after the initial lean spike to deal with the higher engine load, and increased combustion temps that were coming sooner with each fueling change.

The lean spike has become a larger problem with the step up of the nitrous system jets. The nitrous gas is getting to the nozzles much quicker than the nitrous system fuel (alcohol). The fuel solenoid is mounted directly to the distribution manifold. the nitrous gas solenoid presently has a one foot hose between it and the distribution manifold. I've ordered a 3 foot and a 2 foot hose to try out. I'll try the 3 foot first to see if I can gauge any change in the staggered feeding problem. It will also mean that I may need to increase the delay time that the fuel solenoid shuts down after the nitrous gas solenoid to allow time for the nitrous gas to blow down out of the longer line.

I don't plan on the timing retard staying at 25 degrees. I've just started this testing and the last thing I want to do is move too quickly and hurt something. After the fueling problem is addressed I'll start bringing in the timing,... a little at a time. Small steps. Small steps.

 

[Alky V6]

Now imagine a VSC system on top of this.

 

[lazaris]

Now imagine a VSC system on top of this.

Or the correct converter. :biggrin:

 

[Alky V6]

Or the correct converter. :biggrin:

Yes, that option is there too. I just can't resist seeing what I can get out of this converter. The further I push this converter, the more I realize how little of a stall increase I may ultimately need. If I had to guess last year how much more stall I needed to spool this 91mm, I would have guessed maybe 1,000 to 1,500 more rpm. Now, it looks like I could do well with only a 300 to 700 rpm increase in stall. That's quite a big difference. And all I had to do was change some simple jets to find out. I'm not done working on this quite yet.

The things that can be learned if only the effort is put forth.

 

[Dusty Bradford]

The lean spike could also be a false reading. When you hit the brake, the timing drops immediately. The lean spike could be from the unburnt mixture making it's way into the exhaust and burning which would show lean.

My friend is sponsored by NOS and my neighbor is the the field rep for NOS. I think you may have even been at the track when they were filming the Barona episode of drag race high. On long trips I hear plenty of NOS tech and 9 times out of 10, it's too rich of a mixture that takes out the piston. The backfire in the intake is a sign of that. With too little timing and a rich mixture, the fuel will pool on top of the rings until it ignites, when it ignites it can take the rings or pistons out. The nitrous backfire you see all to often on the starting line is caused by nitrous retard combined with launch retard. When a lot of timing is pulled from the engine, it gets into the same category as anti-lag on the clutch cars. Those cars run from 10* BTDC total timing to as much as 10* ATDC in the ignition map while on the clutch. This is what causes the backfiring out the exhaust you see. If a N20 racer pulls to much timing from the engine, it greatly increases the chance of the backfire.

I have no clue about combining n2o with alky and how it effects the engine.

 

[Alky V6]

The lean spike could also be a false reading. When you hit the brake, the timing drops immediately. The lean spike could be from the unburnt mixture making it's way into the exhaust and burning which would show lean.

My friend is sponsored by NOS and my neighbor is the the field rep for NOS. I think you may have even been at the track when they were filming the Barona episode of drag race high. On long trips I hear plenty of NOS tech and 9 times out of 10, it's too rich of a mixture that takes out the piston. The backfire in the intake is a sign of that. With too little timing and a rich mixture, the fuel will pool on top of the rings until it ignites, when it ignites it can take the rings or pistons out. The nitrous backfire you see all to often on the starting line is caused by nitrous retard combined with launch retard. When a lot of timing is pulled from the engine, it gets into the same category as anti-lag on the clutch cars. Those cars run from 10* BTDC total timing to as much as 10* ATDC in the ignition map while on the clutch. This is what causes the backfiring out the exhaust you see. If a N20 racer pulls to much timing from the engine, it greatly increases the chance of the backfire.

I have no clue about combining n2o with alky and how it effects the engine.

You're right. I was there one of the days. The Chevelle was being tested on that day. I was doing some fuel map tuning off the nitrous. This was soon after installing the 91mm.
Maybe your neighbor can give us a clue as to how much retard I should be using. I really have no idea, other than the standard 2 degrees per 50 shot. But nitrous being different with alcohol, I'm just trying to play it safe at the beginning.
Thanks for the tech, Dusty. Very much appreciated. I've heard the same thing from other nitrous users at the track about too rich a mixture causing the kind of problem you described. Of course, that's with using gasoline. Don't know if it's different with alcohol. The excessive timing retard is completely new to me.
Let me get this clear. Those racers you mentioned were stacking the retard numbers? So much rev control retard '+' so much nitrous retard?

I'm wondering if I had reached the rich limit. Maybe that's the main cause of the backfire?

My timing doesn't retard until the nitrous system is activated. When I go on the transbrake, timing stays at 30 degrees. The tight T/C does the rev control for me. No need to retard timing for staging rev control. The rpm stops dead in its tracks at a tad over 2400 rpm waiting for the nitrous. Total delay in the box until transbrake release is around .980 seconds. I have the nitrous activate at any time I choose within that .980 seconds before the transbrake releases. For now, I have the nitrous activate .340 seconds before transbrake release. That nets me a 3300+ rpm launch. Mild to start out with. The lean spike I'm recording only occurs just as the nitrous system activates and timing retards. Timing at activation with the failed test was 8 degrees BTDC with a mixture that was 4% richer than the previous best test that happened to look very good. I was just searching the fine line to see if there was more.
The last best test actually looked and felt so good, I knew I was probably grasping at straws to expect that last 4% increase of fuel to do much better. I'm completely happy with the 3820 test result. I'm going to work with that tune and see if the lean spike can be lessened. With the 200 shot, the lean spike was not as severe.

 

[Dusty Bradford]

I tried calling his cell. I'll try again later to see if he has input on the alky. He was there, tuning the Chevelle.

I would expect too much fuel to cause the same results, regardless of the fuel type.

Yes, the timing retards can be stacked. Remember, these guys are trying to launch 600+ci engines with tons of torque, so they utilize launch retard on top of the n2o retard. When they release the transbrake and the n2o activates. it goes to the timing map of that kit. At the same time some use launch retard that pulls X amount of timing at launch and puts it back in over a set amount of time. If these 2 numbers pull too much timing out, it will backfire.

There are different ways of launching the cars with this set-up. Some use launch retard and turn the 1st kit on at the release of the brake. Others turn the kit on x amount of time after the launch and use a gear retard turned on by rpm to lessen the tire shock at the hit of the n2o.

I'm guessing you found the point where you had too much fuel and not enough timing and that is what caused the back fire.

 

[Alky V6]

I agree. I'll step the nitrous retard back up from the planned 27 to 25 and start working up from there on the 3820 tune.

 

[Dusty Bradford]

I agree. I'll step the nitrous retard back up from the planned 27 to 25 and start working up from there on the 3820 tune.

What size n2o pill are you using and how many of them? What pressure are you flowing at? I assume your using the ecm for all fuel enrichment for the nitrous but if your using a fuel pill. What size pill, how many and what is the flowing pressure on the fuel??? I'm going to do a little research.

From my understanding so far. The hp of the shot will depend solely on the amount of nitrous you inject. If your injecting 300hp worth of nitrous, it's really a 300 hit. The only difference will be the amount of fuel added. I'll know more when I get the jetting info.