Anti-lag...staging spool injection strategy.
 

Working with a stand alone, I've come across something pretty intriguing.

I had the idea of splitting the main event with the net effect of retarding a bulk of injection for spooling the chargers more quickly, and way harder at even a free rev.

What I did was bring in the first half of the fuel at the same initial timing, and the second half VERY late. (This could be done with the post event as well mapped against several variables)

At a free rev with normal injection strategy I might see 5-7 lbs boost.

With the split main, I was seeing 45-50 lbs boost free rev, not loading up with a clutch or converter, simply siting there with the chargers screaming ready to pounce.

Staging with really large turbos or wanting to absolutely punish your drive line could be taken to a whole new level.

Not burning down your converter or clutch for spool the obvious bonus.

taking a note from the old bang-bang technique in the gasser turbo world... retard the ignition and the fire continues to burn well into the manifold, which spools the turbo REALLY well :D

I remember that trick. We used to do that on a buddys twin turbo tempest

Everything seem ok doing that without adverse affect? Sounds interesting for sure.

It works amazingly well.

Retarding the timing helps with spool as well right, however the engine runs like crap, smokes more.

This way, the first half shot has good advance and establishes ignition, the second half comes in too late to contribute to combustion in the cylinder and burns up late driving the turbine.

Its the same reason the third gens spool better, thats when the post injection event is active, I've watched it in the scope and its amazing how well it helps.

Those with third gens, if you've done it enough, if you give it just a little too much throttle, the post event shuts off, and spool will drop at that point or you might not even spool if your trying to push a large turbine.

The one side effect of course is heat, it don't take long to reach 1400, this is what is driving the turbine. Would you want to sit there for ten mins doing this no....but for a short stint staging no problem.

I see no reason why you couldn't drive the heat up to say your max egt's on a full bore run.

With the stand alone, I could just tick off points of timing with a single click of the keyboard while at RPM on the fly.....so it was less than a few mins to maximize the effect.

I'm thinking this could be done with efi live, have zero experience with it....but sounds like they can manipulate most everything. Not sure if they could bring up the post shot volume enough or not.

Maintaining the post shot at RPM would be the first step.

the heat isn't going to hurt anything... it's 1400* EGT... the burn is so late, you're seeing a lot of heat at the turbine, but not nearly as much inside the chamber/on the piston

Man those electronics have their advantage in some instances as you've found out. I recently went from 18 to 24 timing on my daily driver and it's cleaned things up at part throttle excellently at the penalty of a bit of spool but that's not really even noticed given the small 62 I run. Pretty cool having your cake and eating it too. Cool deal!

but how long can that wheel take the heat before the metal starts to fatigue

I agree, no reason why you can't raise the heat to the point your comfortable driving the turbine at. 1400 isn't the limit though, wasn't hard to drive it way higher......something you'd still want to monitor.

Long long time if you keep it reasonable.

pulling trucks make 2000*+ going down the track... a bone stock truck will make 1500* pulling in the mountains

not sure what temps will burn what wheels, but I wouldn't worry much about 1400-1600* while staging

This discussion probably belongs in it's own thread, but high EGT's during staging does cause problems. The way the Cummings head is designed, the heat from the exhaust port is directly exposed to the water curiculating past the exhaust valve seats that normally drops. Ever notice it's the same valve seat that drops? The one between the cylinders. The MLS gasket already channels a lot more water to the back of the block, to help out cylinder 5 and 6. Super heating the remaining water is not a good idea.

Keeping the EGT's down to around 800-900 while staging is a good idea. Now if Chis could initially make the injection late, and once the boost is up get rid of the late injection to cool the EGT's back down. That would be way cool! It would probably be easier to maintain a steady boost, if the advance was put back in.

Paul

Paul

interesting...

also interesting that you have a couple highly modified trucks and don't know how to spell cummins :(

lol

Subscribing!!


I'm sure Paul did that on purpose ...."Cummings"....

oooo busted... dont worry Paul, I have caught myself doing that a couple times

I'm just ribbin' him ;)

it is a good/interesting point on the cylinder head layout

Yes, exactly. Thats the sweetest thing about this standalone, you can map the late fuel say against, RPM....Boost you name it.

Fuel could come in late until say 20lbs boost, then the injection strategy would go back to normal.

Egt's will naturally go higher the higher you boost to. The 50 psi example I gave was the highest I could boost to using this injection stratagy.

Likely you'd never leave the line at 50 psi, tran's would be hating life thats for sure. BUT if you could hang on to that...damn.


On the heat issue with the head, it makes sense. Staging with a converter your rpm's are fairly low....water pump output less. Limiting the time staging can't hurt.

Thing is, I've put more heat to this head than ever, pulled some crazy stuff with timing, buried the 2000 pyro several times.....no dropped seats as of yet.



I remember you posting on your runs you max out at 1250 or less, yet have had multiple seat issues? I'm still in the camp that cylinder heat that drops seats. Egt's might not be the best indicator.

Chris, with the boost advance your seeing, VS a stock tune, like your first post, what was the RPM, seems to me that CFM plays big part here.

Are you just stabing the throttle to see these #'s? or are you at a steady rpm?

in other words @ 3000 rpm stock tune what is the boost?

" " modded tune what is the boost?

Be very, very, very careful when adding heat after the exhaust valve opens. I've melted more than my share of turbines and exhaust housings with late fuel.

so are you basically making it have three injection events like a 600 motor but have the last comein late then when you reach your preset boost of say 20# and th eturbo is lit well having it go back to 1 event like a 12 valve? If so can you program to add the injection events back in say when its coming down in rpm so when the sled hits and its pulling down the rpm the other events would kick in and help keep the charger from snuffing out at the end of the track? Not for sure if i worded that correctly or not mainly just wondering if that is even possible or if there would be a benifit there?