Stock rail, stock pump, stock injectors, almost stock power with this retune. I may have picked up some air in the fuel lines as I was running the car near empty but I've seen spikes before. I forgot to log all my runs so I'm not sure. Note to self, write down everything as close to real time as possible! A fuel pressure gauge at the rail is coming soon. At my power levels and boost levels no one believes I'm running out of fuel .... unless the fuel pump is going out.

Les

 

You are dumping so much fuel because of your high engine temps, that you are hitting the limitations of your fuel system. So why would you try to even fix that? So you can have plenty of fuel to run 9AFRs? You need more cooling not more fuel.

 

That would makes sense except I was in the 9's with the engine cold. The washer tank is dry now so pure water is going in. I didn't have a lot of meth mixed in but .5 AFR could be from the Meth. Normally I don't see the ECU dumping fuel until the ECT's reach 240º which I didn't reach this time. High IAT's and the ECU pulls timing. At least that's what I read in my logs. This is going to require some more trial and error and dyno tune. I'm close to hopping on the dyno tune or no tune wagon.

Les

 

unless you loop the rail the pressure readings will be inaccurate les. when i had a oem rail i read 57 psi at the schrader valve. then i looped the rail and read 55psi showing a 2 psi drop or rather a true reading as the flow is equalized. when i stacked the pulleys i went to 50 psi at wot showing the pump is dropping pressure due to demand from the injectors. without looping the rail the pressure reading would stay the same as the reading is at the end of the wall so to speak.
im dropping 6* of timing during my 1/4 mile runs due to high iat temps. 160* iat the ecu is shutting me down

 

I'm now spraying 100% water and the surge is the same. The installer thinks the spark is being blown out by the water when the throttle body abruptly (fly by wire) mostly closes. I'm still waiting for my replacement cable ..................... still waiting ............... still waiting .............

Les

 

Is this surge definitely caused by the injection? Have you run with the injection disabled to rule that out? It's all hearsay for me,because I haven't done it yet myself; but from what I've gathered, the 5gph nozzle(pre t.b.) is not at all exorbitant. And the SC is evaporating/vaporizing that spray(cooling). That's why it's hard to believe it would hinder the spark. Others have sprayed larger nozzles, as well as additional nozzles in the intake mani.'s without blowing the spark out. I'm totally rooting for you to get this figured out Les. That last tune you got certainly messed up the momentum.

 

I think it's tune related. My current tune is super rich, high 9's low 10's, and until I get the tune ironed out on gasoline I'm wasting my time playing with the injection system. Having said that, it doesn't "surge" when the injection system is off. When it happens it feels like the motor quits and then starts at wot. It only jolts hard once but it's a hard jolt or surge. The shop used the 5 gph nozzle but it's set to reach full pressure at 25 psi which it never reaches. On these tunes the throttle body opens and closes at an accelerated rate and perhaps the speed it's closing is contributing. IDK. The shop told me a car would drown out the spark at an AFR of around 9.4 which is the reason I mentioned it as a possibility. We shall see when all the apples fall off the tree.

Les

 

Hopefully the fuel pressure gauge will be on a hose so you can monitor it while at WOT. Or, maybe can find a pressure transducer and log it during a run to see if fuel pump is keeping up with demand.

 

Well, Les I was hoping for some good info. Rudy shipped me his Snow kit he never used, but it was lost in transit. So, I haven't been able to plumb anything so far. If he finds his, I will use it, if not, then I will have to order a new setup. Mani's are ready, and all I have left to do is mach up a plate to hold the battery, the pump, and tank. Well, I do have to mach up a fitting on the Y-pipe for a sensor, but won't take long. I should be ready in a week, 2 at the most to start wiring and plumbing. A lot of bung installs lol....

 

dont want to hyjack - but is the 160F (71C) AIT measured pre or post compressor + cooler or pre compressor?

 

Post, otherwise it would inaccurate data for the ECU. The IAT sensor is in the Y-pipe, which is after the supercharger.

 

yes thanks - the manual was a little confusing
So the MAP and AIT are post chager/cooler.

so its 160F (71C) at what pressure and flow after the cooler - psi? and cfm?

 

I participated in another 1/2 mile event on the 23rd of june and logged 4 of the runs. I haven't compared them to logs from the prior 1/2 mile event but I saw the IAT's reach 172º at 140 mph at the end of the run. I was spraying a 60/40 mix of water alcohol. It was 95º ambient air temperature and hotter on the runway. Starting IAT's were 115º, some runs a little more and some a little less. After the 3rd to 4th shift they were at 140º and seemed to pause a moment before continuing upward. Speaking plainly, the water injection isn't helping much, if at all. One observation of interest. I sat idling for at least 30 minutes with the air on while the photo cells and timing equipment were trouble fixed and my IAT's dropped to 10º over ambient. I never see less than 20º over in normal driving. What's it mean? I'm not sure. Knowledgeable speculation welcome.

Les

 

I would guess that the AC runs the fan at 50% and idleing for a while really does not produce much heat. The supercooler had a nice constant air flow throught it with little heat to reject.

 

That sounds precisely right. Regarding the Meth/Water injection; have you experimented with larger nozzle Les? I know that Rodney at AIS says to use a much larger nozzle (pre SC) than what you originally mentioned you were using. I know that some use dual and tri-nozzles in a cooler climate than where you're located. There are many variables I know, but I think the real question would be; how hot would it have been w/o the injection? It would be very disappointing to find out that all these MethKit manufacturers claims are BS.

 

I'm spraying before the throttle body and most of the cooling capacity is being used cooling the supercharger and then passing through the intercooler. My guess is the water from the intercooler is now heating up the air. From my information gathering it was clearly going to happen but I'd believed I would still see cooling benefits to the IAT's and ECT's. The nozzle and the settings I'm using were based on the dyno with a prior tune. We dialed it back because it was costing some HP set to 100%. With the current tune perhaps it would be beneficial to spray more volume. The bottom line is this isn't a bolt on and it'll work type modification. It's going to take some trial and error to get it dialed in. So far it's been error, error, fail. I'm not done with it yet.

Les

 

That is so true. Glad that you're not done w/ it yet. I wish I could be doing this right now, and comparing notes, but it just isn't a good time for me right now to be playing w/ it. I wish you success Les; good luck.

 

Noob to SRT6/SLK32's here

At 750cfm intake (@6200rpm) (excluding H2Ovap) and 14.5psi boost, I calculate to drop your AIT's by 50F (32C) you'd need 6ml/sec (about 1pint every minute and a half) of injection (water only at 2250kJ/kg Hvap), however as you probably know, this generates H2O vapour (32cfm) which dilutes your O2 down from 21vol% to the low 19vol% levels - with obvious consequences.

I havent analysed the reactions in the cylinder fire - but I think I recall the H2O is a power neutral addition to the fire, since whatever it gets involved in - it should end up as H2O out the exhaust - but not sure on any total gain in this regard.

How much water you adding for your dT on your AIT's?

 

les during your runs how often are you at wot? im having a killer chiller installed this week and hope to see 30* below ambient during normal driving. it should shutoff at wot as the a/c cuts out but my tuner is looking at allowing the ecu to keep the a/c on at all times when the switch is engaged

 

I'm preparing a 1/2 mile thread as we speak. I don't think I reached WOT in first but from 2nd gear up to 140 mph I was deforming the floor. My starting IAT's were around 112º, 140º after the 3rd to 4th gear change and then climbed to 172º at 140 mph.

Les