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Been On The Dyno Again (To Reduce Power)


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I have now got a car with dual identity, as you can see the boosted map ran 242bhp and 256ft lb of torque (same as before) which is great fun but hard to drive when trying to drive steady on a cruise up the motorway. so i have been trying to figure a way to hold the supercharger at bay which i have now designed and tested. so went to the the dyno again to get the 2nd map rewritten the car is is now truly awesome, i can have a normally aspirated easy to drive car with 130bhp then flick a switch on the move and have 242bhp making the car fast as feck !

 

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I always considered a switch supercharger set up lol more for a "Mother in the car" mode :rofl:

I can't see from those dyno curves that the cruising is an issue based on power/torque? In your cruising range (say 3k rpm +/- 250rpm) you only gain 15ish lb/ft over that range at full throttle, right? I reckon the issue is more in the map than the power. But when you say drive steady, how do you mean? As in you keep finding yourself jolting forward of feeling like it suddenly came off throttle i.e. maintaining 70mph? You could probably get that from a too sensitive throttle pedal or no smoothing factor in your map. Or simply cruising area on your map needs more work to refine it? Like I said, I can't imagine the drive-ability is so bad looking at that dyno curve, probably considering there are similar weight/power cars that aren't having these issues....?

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Nothing to do with mapping, it's to do with the twin throttle body set up and bypass valve, at cruising throttle the engine load is light keeping the bypass open meaning no boost. Slight change in load and plenum goes from vacuum to positive pressure closing the bypass and giving massive torque instantly. Meaning trying to cruise at 70mph is hard work. Thus the dual map and lo boost option. IE cold, damp, cruising, missis in the car mode.

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Ah yes I forgot Rich does the twin throttle body. Having not looked into it at all, is there not a way to ease it in? The charger used to have a clutched pulley did it not on the Mercs? I'm guessing there is a lot more electrical trickery involved bringing that in smoothly at 3k rpm (if I remember reading up on it a couple years ago lol)

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the merc clutch pulley is way to big, in order to use it would have required doubling the size of the crank pulley to get the right ratio. The thing with the car is on full power map the car is an animal and very tiring to drive, having the option of switching it off is great it makes the car more usable day to day and as far as i,m aware unique...

Edited by DanE
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The thing with the car is on full power map the car is an animal and very tiring to drive, having the option of switching it off is great it makes the car more usable day to day and as far as i,m aware unique...

 

I've got a switchable mapped ECU as well but mine just switches between a full power map and an emission-friendly map (for MOTs in the future). I've labelled the switch on the dashboard as 'Turbo ON/OFF' 8) (no, I don't have a turbo).

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