Advancement of fuel delivery?

[Alky V6]

What I'm thinking about for my own project is injecting a small amount of nitrous around the turbo compressor area. Position still to be determined. Maybe trying different positions, since it's only a matter of setting up 1/8 npt bosses. Still using the large system to spool the turbo via exhaust mass flow, but having the small system continually inject throughout the pass to give me just that little edge. Mainly, just enough to break into the 8s with a T76. Just like what Scott has done.

I'm talking about starting with a tiny 25 shot maybe, harmless really, and seeing what I get.

Small steps. Small steps.

 

[TurboTR]

It can work, but the small problem there is the compressor blades are not angled correctly for that (unlike the turbine side). We shot compressed air like that for spoolup assist on a turbo diesel truck efficiency enhancements project.

Be sure to have adequate timing retard (and fuel to match) for your small shots and there's no reason to be worried. You'll hardly even sense a 25 shot- it's tiny compared to your current power level. A 50 shot will just whet your appetite for more Plan to put a 100+ shot on it

TurboTR

What about injecting directly into the scroll. Directing the spray to help spool the turbo. Much like blowing on a pin wheel.

 

[Alky V6]

Thanks TurboTR. Your advice is reassuring. I see your point on the blade angle. I'm thinking that I'll inject the way Scott has. The shot size will only need to be enough to click off an 8.xx. That will satisfy me. If I don't feel it, that's fine. After the 8 is under my belt, I'll probably turn the knobs down and let the engine live a long life.

On another point. I noticed your sig. From your experience, have you been able to come up with a general max cylinder pressure limit with our engines?

Is this the same fellow from long ago that started tuning services using cylinder pressure measurements? King?

 

[TurboTR]

How much do you plan to retard the timing for your nitrous?

You probably remember me correctly; in fact you built a max effort 200R4 for me around the mid/late 90's. I worked at an engine research institute for several years around then as well.

Personally I'm comfy with about 1600 psi peak on my own engine. I don't know how much more it could take safely, but when I hold it ~ to that it shows no gasket damage, etc. It's probably on the very conservative side. But in general most engines would probably do well to stay below 2000 psi peak. Even for heavy duty diesel hardware- ours is not as strong.

Don't confuse what you get from BMEP calcs with real cylinder pressure (as we've mentioned before).

The good news is, a statement like "Nitrous works by drastically increasing cyclinder pressure...", which you see in any popular rag, etc is... dead wrong in fact. At least when done correctly- it can of course drastically increase the cyclinder pressure, but then you need to make sure to include a good quality engine parts broom in your tow rig too. That statement (and equivalent) is generally accepted because it seems to make intuitive sense at first, but the reality is that the engine simply cannot keep a lid on and withstand drastically increased cyclinder pressure (along with the drastically increased forces on everything). The real mechanism for increased power is not as obvious, but fortunately for all of us who love drastically increased power it's not via "drastically increased cylinder pressure".

TurboTR

 

[Alky V6]

Ahh. It is you. You even remembered that discussion we had. Hope everything is going well with you.

The amount of retard I'm presently using is 8 degrees. I have used as little as 4 degrees, but the circumstances that I used it in scared me a little so I added 4 more for a total of 8 until I was sure the fuel map was squared away. Actually, that is still an area that I can play with if I feel I need a quicker launch. As long as traction doesn't become a problem. The one time I tested it with just a 4 degree retard, traction wasn't a problem, but the fact the wheelie bars weren't on the car that time was. I was definitely caught off guard. The throttle pedal kinda jumped off my foot, if you know what I mean.

I just finished studying the latest datalogs and the nitrous is on for a total of .425 seconds from going WOT, to spooling the turbo to 16 psi @ 4,655 rpm. At .646 seconds from going WOT, the boost has reached 283.8 kPa @ 5,632 rpm.

 

[Alky V6]

Todd. I'd appreciate it if you could enlighten us a little more on your last statement about the circumstance in which nitrous gives us dependable, safe power.

 

[Chevota]

Thanks TurboTR. Your advice is reassuring. I see your point on the blade angle. I'm thinking that I'll inject the way Scott has. The shot size will only need to be enough to click off an 8.xx. That will satisfy me. If I don't feel it, that's fine. After the 8 is under my belt, I'll probably turn the knobs down and let the engine live a long life.

On another point. I noticed your sig. From your experience, have you been able to come up with a general max cylinder pressure limit with our engines?

Is this the same fellow from long ago that started tuning services using cylinder pressure measurements? King?

Can't wait for that video Don Don't care to much about what the time board says as much as studying the launch and 60ft mannerisms. Fortunately the majority of my runs are un-eventful as opposed to yours. Watching your runs that you posted on You Tube confirms just how tight you convertor is! I also think it might be negatively affecting your et's to a certain extent downtrack. I have several thoughts regarding your "new setup" as well as some new ideas you might want to look into. Not much of a typist so I'll be giving you a call tomorrow instead of posting if that's ok?

scott wile

 

[TurboTR]

BTW is that 284 kPa boost, or MAP?

As for the nitrous, and especially with our relatively small shots (like say < ~ 200 hp) it's probably safe to say that basially it's just another increase in air density. As long as it's all mixed well, there's plenty of matching fuel to support it, and the cylinder pressure is kept under control via adequate timing retard the it's pretty much just like increasing the air density any other way. My own experience with up to a 175 shot (so far) on top of ~ 30 psi boost (old 76 q-trim at the time) supports that- I haven't even seen a discolored spark plug with it, much less any hg damage or worse. But I did take great pains to make sure the gas mixing was good (sprayed well ahead of the tb, including several bends in the piping to help mixing), the fueling was good (via the port inj), the retard was good (via the FAST), the a/f control was good (via the FAST wb02 closed loop), etc. The guys that run 4 sec 1/8th miles with 3 big stages of gas on a huge BBC might have more to add about it though.

One thing to consider when planning your spark retard with the hose is that the relative amount of nitrous per intake stroke goes down as the rpm goes up. Is probably the main reason that it's 'known" to make midrange torque IMO- down at the lowest rpm where the spray turns on each cylinder is getting the biggest relative dose of nitrous, compared to the dose at higher rpm. IMO the retard can also be adjusted accordingly to better suit the effect, if you have a spark map rather than a distributor and straight MSD spark retard (like most of the carb'd nitrous guys for example). Speaking from a "street/strip" perspective- OTOH, if your race engine never sees like < 7000 rpm during a run it's likely a wash. But for example, at 6000 rpm there's 2x the number of intake strokes vs 3000 rpm, yet the amount of nitrous being injected has remained constant. So each cyinder is then only taking in half the amount of nitrous amount per stroke at 6000 rpm than it does at 3000 rpm. Hope that makes sense.

TurboTR

I just finished studying the latest datalogs and the nitrous is on for a total of .425 seconds from going WOT, to spooling the turbo to 16 psi @ 4,655 rpm. At .646 seconds from going WOT, the boost has reached 283.8 kPa @ 5,632 rpm.

 

[Alky V6]

Can't wait for that video Don Don't care to much about what the time board says as much as studying the launch and 60ft mannerisms. Fortunately the majority of my runs are un-eventful as opposed to yours. Watching your runs that you posted on You Tube confirms just how tight you convertor is! I also think it might be negatively affecting your et's to a certain extent downtrack. I have several thoughts regarding your "new setup" as well as some new ideas you might want to look into. Not much of a typist so I'll be giving you a call tomorrow instead of posting if that's ok?

scott wile

Scott. Check your email. I sent it earlier today. If it didn't get through, let me know. I look forward to talking to you. Thanks.

 

[Alky V6]

Sorry. That's map Todd.

 

[six shooter]

Donnie,
Any chance you can post up one of your data logs ?

 

[Alky V6]

Donnie,
Any chance you can post up one of your data logs ?

I'm not sure how I would do that. I have a better idea. Go to Electromotive's website. Download their latest WinTEC software. It's free. After you have it up and running, let me know and I'll email you the data file. That way, you can examine it much better.

 

[Alky V6]

BTW is that 284 kPa boost, or MAP?

As for the nitrous, and especially with our relatively small shots (like say < ~ 200 hp) it's probably safe to say that basially it's just another increase in air density. As long as it's all mixed well, there's plenty of matching fuel to support it, and the cylinder pressure is kept under control via adequate timing retard the it's pretty much just like increasing the air density any other way. My own experience with up to a 175 shot (so far) on top of ~ 30 psi boost (old 76 q-trim at the time) supports that- I haven't even seen a discolored spark plug with it, much less any hg damage or worse. But I did take great pains to make sure the gas mixing was good (sprayed well ahead of the tb, including several bends in the piping to help mixing), the fueling was good (via the port inj), the retard was good (via the FAST), the a/f control was good (via the FAST wb02 closed loop), etc. The guys that run 4 sec 1/8th miles with 3 big stages of gas on a huge BBC might have more to add about it though.

One thing to consider when planning your spark retard with the hose is that the relative amount of nitrous per intake stroke goes down as the rpm goes up. Is probably the main reason that it's 'known" to make midrange torque IMO- down at the lowest rpm where the spray turns on each cylinder is getting the biggest relative dose of nitrous, compared to the dose at higher rpm. IMO the retard can also be adjusted accordingly to better suit the effect, if you have a spark map rather than a distributor and straight MSD spark retard (like most of the carb'd nitrous guys for example). Speaking from a "street/strip" perspective- OTOH, if your race engine never sees like < 7000 rpm during a run it's likely a wash. But for example, at 6000 rpm there's 2x the number of intake strokes vs 3000 rpm, yet the amount of nitrous being injected has remained constant. So each cyinder is then only taking in half the amount of nitrous amount per stroke at 6000 rpm than it does at 3000 rpm. Hope that makes sense.

TurboTR

You bring to mind a very good point. Since the amount of nitrous that ends up in the cylinder changes with rpm of the engine, the amount of ignition retard can be changed relative to rpm. It does not have to be a straight ignition retard number across the board (rpm wise). If you're starting the injection at a very low rpm, say 2,000, which is the lowest rpm you should be spraying anyway, then you would most likely want the most, safest amount of retard, at that point. As rpm rises, you can start putting ignition lead back in. The thing to remember when putting lead back in is that as time builds from the starting point of nitrous injection, so does cylinder temperature. So, depending on the size of the hit will determine how fast and how much ignition lead you can start putting back in. Newbies to nitrous should stick with a safe, straight amount of retard during nitrous injection. But Todd is absolutely right. You can play with the hit intensity with the amount of retard. You just need to know where the limit is.

Another point that has been stewing in my head that I should bring up. When using nitrous with alcohol, the mixture is so cold that maybe a lot of retard is not necessary, even at initial injection at a very low rpm (2000 rpm).

 

[Hot Air]

Donnie,
Point is well taken on the charge temp due to the cooling effect of methanol and nitrous. Are you measuring air temp in the intake? If so, what temps are you seeing? Must be like the Artic!
Conrad

ps...Donnie and others, I really enjoy learning your though process. You guys know no boundaries. Most of us think 'inside the box'...ie what everyone else is doing. You guys have trampled the box and set it on fire! You are simply "over the top"!!!

 

[Alky V6]

Donnie,
Point is well taken on the charge temp due to the cooling effect of methanol and nitrous. Are you measuring air temp in the intake? If so, what temps are you seeing? Must be like the Artic!
Conrad

ps...Donnie and others, I really enjoy learning your though process. You guys know no boundaries. Most of us think 'inside the box'...ie what everyone else is doing. You guys have trampled the box and set it on fire! You are simply "over the top"!!!

Since I'm port injecting with very short runners, I haven't tried to measure the temp after the nitrous nozzle. The IAT is in the up pipe and temps are what you would expect from other similar setups.

I do know the temps after the injectors and nitrous nozzles must be well below freezing. After a cold startup of the engine on alcohol, I have to drain water out of my plenum. Right after startup, ice is forming inside the plenum, that melts as the engine warms up. Most intakes are designed so that this water will just run into a runner(s). My design does not. I wanted equal distribution and mixture and didn't want any trace elements running into just a few runners upsetting the power balance.

I appreciate your comment on the thinking outside the box. It surely is what I enjoy most about my project and my sharing is meant solely to encourage others to do the same.

I realize that some people may think that I'm doing this thread to show off. Nothing could be further from the truth. What I enjoy even more than my own creations is the out of the box creations of others. And there just isn't enough of it.

 

[Alky V6]

I was just studying my latest datalogs and realized that the elapsed time markers on the timeline aren't accurate. Ignore any reference I may have made to how long into the run certain events take place. It appears the numbers might be around half what they should be.
.5 seconds should be 1.0 seconds, etc.

 

[Alky V6]

I was just studying my latest datalogs and realized that the elapsed time markers on the timeline aren't accurate. Ignore any reference I may have made to how long into the run certain events take place. It appears the numbers might be around half what they should be.
.5 seconds should be 1.0 seconds, etc.

I was just turned on to this site! You have to check it out!

Data Log Lab

 

[Alky V6]

The Milestone Breakthrough with the Tuneup

This engine craves fuel. I'm presently at a mixture strength of 4.5 to one and I'm toying with the idea of increasing it. But first, I need to increase the size of the mechanical injector nozzles. I'm throwing all I presently have at it. Alcohol is an amazing fuel.
The present launch stradegy is going WOT on the second amber (from a staging rpm of 2300 rpm) and releasing the transbrake on the third amber. At the launch, the nitrous brings the boost to 16 psi @ 4654 rpm in about .8 seconds.
The nitrous is activated upon going WOT as long as rpm is at or above 2440 rpm and map is at or above 98 kPa.

 

[Alky V6]

The reason why the rpm is not higher by 16 psi is because the torque converter is tight. Stall is 2400 @ 0 boost.
The mixture during nitrous activation maintains 4.5 to one. After nitrous shut down at 16 psi, and as rpm increases, mixture strength decreases to 4.76 by shift point.

 

[Alky V6]

The main problem I have been fighting has been a lean spike as the nitrous turns off and the aux fuel comes on. I don't remember if I'd already discussed it, but I've added an auxiliary fuel rail inside the plenum of the intake with mechanical injector nozzles pointing down each intake runner. The aux fuel was first setup to activate at 16 psi.

So, the nitrous turns off at 16 psi and the aux fuel turns on at 16 psi also.

I started about solving this problem by tuning the systems separately to try and isolate which system was causing the most problem and it also made it easier to come to a solution for each system without another system muddying the pond.