Im also curious if there has been any word on haltechs progress with this.. Im going to be running meth inj on my project so the idea of fuel cut under boost with meth has disaster written all over it..think it would still be worth writing them or would it not make a difference at this point?

 

I'll actually follow up and see.

 

i was doing some open loop Wastegate tuning a month ago and entered an overboost situation with my ViPEC V88. i was looking for the control curve in relation to RPM around boost initiation from zero boost at the 5000 area rolling in. i found as you enter boost from a higher rpm initiation the duty cycle need to be reduced.

i revisited my log just to get an idea as to how ViPEC deals w overboost. BTW, no harm to the motor from this event.

here's what occurred:

last data before ViPEC overboost

time: 4 minutes, 39 seconds 540 milliseconds

Wastegate Duty Cycle 94.5%
Lead ignition 15.2 (11 trail)
Injector Duty Cycle 29%
Boost 12.4 psi
TPS 28.3
RPM 5175

next logged data point is 4:39:642 a tenth of a second later (i was logging at 10 Hz, am now logging at 50, what a difference)

Wastegate Duty Cycle 10%
Lead Ignition 6.1 (11 trail)
Injector Duty Cycle 41.4
Boost 21.4 PSI
AFR 10.7
TPS 60.9 (i was rolling into the throttle)
RPM 4962

looking at the above it is clear that the ViPEC overboost program includes ignition retard, boost cut and modest fuel reduction. ViPEC generally is excellent as to full disclosure but does not disclose the details here. they do use a rotary specific response.

 

Thanks Howard. Excellent info as always. I'm going to go back through my logs where I was hitting the fuel cut on the haltech and see if I can find some comparable data to see if it does anything else along with the actual fuel cut.

In other news, I got a response from Haltech Matt today on the request for ignition cut and his thoughts on the effects of spraying methanol during the fuel cut. Apparently nothing has been decided on the addition of the ignition cut feature yet.

I would not be too concerned about combustion occurring. You would have to have a considerable amount of methanol in the spray to allow the mixture to be rich enough to allow combustion. Especially so with a rotary engine which has a very low lean tolerance for combustion. Even if the methanol was half of the fuel being provided I doubt any combustion would take place.

I'm not sure how much I believe that story, but maybe one of the combustion experts like Howard or arghx can weigh in there. I feel like between a full flowing methanol spray, residual fuel in the runners and firing coils a lean combustion cycle would for sure be possible. Matt suggested that in the meantime as a temporary workaround you can map your RPM Limit against MAP so that if the MAP exceeds a certain amount you will trigger a lower rpm limit, which is an ignition cut. You would simply set the overboost fuel cut above this threshold or turn it off in the software altogether.

I'm thinking something like this would work for a 24PSI rpm limiter based overboost cut



-Skeese

 

Nice work Seth! #TeamNoSponsors I'm definitely copying this!

 

Here's how I'm implementing mine in regards to Flex Fuel usage. I value boost vs. flex fuel > boost vs. engine temperature. I hardly even move my cars without getting them to 140F+ anyways, so I don't think I'll need that feature.





This effectively does the same thing but limits via Ethanol Content, not temperature. Love it. Thanks again Seth.

 

Also, check out your ESP Software version. I was on 2.00.27 using 2.23.0 release files. Now I'm on 2.00.29 w/ 2.24.0 (or rather need to convert my map over to that). There has to be an easy way of doing the conversion...

 

Just FYI to all, this happened a few months back. There is now a drop down in the overboost cut tab that gives you the option of fuel, ignition, or fuel and ignition cut for an over boost condition.



Skeese

 

This is just a question but do a lean mixture burn faster in the combustion chamber and that's why we have this problem?
Even if you cut ignition and a lean mixture of gasoline or meth enters wouldn't you get knock/detonation problems anyway if the mixture pre-ignites?