Would it be possible to map boost against time? I'm working on a street legal FWD drag race car. And it would be nice to launch with a low boost setting. And get higher boost after a couple of seconds.
I think it should work like this.
- Press clutch. clutch switch is activated.
- Press button on dashboard. Now VEMS knows you want to use time based boost control
- When you release the clutch vems starts counting. And follows a map where you can set seconds and boost levels.
- so how would this work after a gear-switch ?
- easy way is to use steering wheel button to hold startline RPMs, then start timer (boost) sequence upon release. Another way is to use VSS (vehicle speed) to turn off rpm limit and turn on boost control. //KevinBlack
- so how would this work after a gear-switch ?
Is it possible to program this? Or do you guys have other ideas on how to control wheel spin on fwd cars?
- usually gearbox switch is applied, that is gear dependent boost instead of "time-based"
- note that you have a throttle, and properly configured TPS-based boost helps a lot in drivability (more predictable and adjustable TPS=>power). It makes no sense (really!) to configure TPS max independent max boost (even though we often see that).
- This is not need, the boost depends on TPS position if the boostcontrol is tuned properly. So if you to launch low boost, you have the launch lower TPS. -FERO Exactly!
- TPS power control is not always possible on tuned cars, Its very hard to control power, and you usually need to launch in full throttle, but with limited boost. It takes forever, if even possible to get boost on half throttle on a balanced engine. Only possible on a car with a ridiculous sized turbo. Time delay boost target is a good idea, and if easy it should be implemented. Also a special boost target with launch control active. //Emil
- I think the best solution would be if we could have vehicle speed sensor and boost dependent of vehicle speed. //Tonci
- isn't it best to (as originally planned and prepared) have boost-target table with multiple lines, based on input ? Gearbox input would be most useful, since gear + RPM => speed. 45km/h can be gear1, gear2 or gear3, with all different RPM and behaviour. While most can allocate a free analog channel, a trigger channel is often hard. (well, some can allocate trigger easier than analog in...)
- But how would you make a switch that's sees witch gear you have selected? Isn't this hard to do on a gearbox without this as standard?
- If you have a VSS (vehicle speed)input then the ecu uses RPM to know what gear the car is in. Good way to control boost for street FWD is 4 boost tables(one for each gear), RPM based to allow soft transitions. But time based boost is very easy and very good for drag racing. Regardless I'd very much like to have a front and rear wheel speed input to log vehicle speed and wheel slip. //KevinBlack
Lets say I want vems to hold my revs to 3500rpm with tps at 100% at the starting line. Why does he apply TPS=100% if he could simply do what he want with lower TPS (say, appr. 83..87%)? So boost builds up before I actually launch. But i want only 0,5 bar boost. And after a set period of time I want the boost to rise to 1 bar.
- Difficult to control and likely inconsistent. Best way is to be at WOT. //KevinBlack
This way I don't have to wait for the boost to kick in when doing my run. But I don't want full boost when starting to limit wheel spin.
There are a couple commercial products out there that offer time based boost control. But integrated in vems is much nicer ofcourse :)
Is it possible to program this?
yes, possible
http://www.innovativeturbo.com/pdfs/msbc12g-manual.pdf
This is what i mean. Real drag race boost control. I thinks i'm gonna buy this unit. But would be cool if vems can do the same in the future