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Non Member
2501
Wed Apr 14, 2004 10:26 pm
Cumbria
Non Member
5602
Thu Apr 15, 2004 12:33 pm
Fleet, Hampshire
stephendell wrote:Nitrous + boost + Renault clutch.........
= Slip, slip, slippery slip
Still worth a go though
Non Member
594
Thu Nov 17, 2005 5:35 pm
york
peterg wrote:
I suspect you are merely mulling things over anyway, as what youre proposing (cams, ECU and nitrous) is going to set you back several thousand pounds in all......no harm in asking the questions!!!
Non Member
594
Thu Nov 17, 2005 5:35 pm
york
peterg wrote:
As I proved on the Isle Of Man this week power isnt everything.....the Nissan Sunny GTI-R I was up against was a serious bit of kit with 400bhp and I beat him by a significant margin on the Jurby pursuit sprint. (got killed on the Lhergy Frissell hillclimb, but then it didnt really suit the GTA...or driver!! ) and the supercharged Viper was a 700bhp monster.....that couldnt be tamed!!!!! (slower than me on all 3 events!)
Non Member
2501
Wed Apr 14, 2004 10:26 pm
Cumbria
Non Member
3474
Thu Apr 15, 2004 8:10 am
Colchester, Essex
gt5 wrote:re; the ecu im confident the Dastek will do its job with everything else including controlling the Nitrous (If i go that route). :
Non Member
594
Thu Nov 17, 2005 5:35 pm
york
peterg wrote: The Dastek wont allow you to sort out the cams as it isnt controlling the ignition advance, you are gonna need a proper ECU with crank trigger wheel etc..
Non Member
594
Thu Nov 17, 2005 5:35 pm
york
David Gentleman wrote:gt5 wrote:re; the ecu im confident the Dastek will do its job with everything else including controlling the Nitrous (If i go that route). :
Right, Im going to explain this in detail about the fueling system on ANY type of piggyback unit, Perfect Power, Dastek etc...
On the factory ecu, depending on what voltage is received from the MAP sensor on inlet manifold pressure, it tells the ecu what amount of fuel to put in.
The map sensor has a range of 0-5v, 0v being idle and 5v being 14.7psi of boost (maximum), 4v is about where a standard GTA runs at 10psi of boost, so to make it simple, imagine 4v is 200bhp (standard), 0v is 0bhp (idle) and say 5v is 230bhp (to simplify things..)
Now the piggyback units work by intercepting the signal from the map sensor before it reaches the factory ecu, so for instance, if you were running 10psi (4v map), the piggy back could tell the ecu that the engine is running 4.5v map and thus put extra fuel in (the same amount of fuel required for say 12psi...)
BUT, and this is the problem..., if you are running 14.7psi, and the car needs more fuel, then there is nothing the piggy back can do. It can't make the ecu see '6v' for instance, as it doesnt exist, the ecu only sees 0-5v..., thus max it can do is 5v, which is what it currently is at already. On top of that, the factory ecu cuts out at 14.7psi (ecu seeing 5v, for safety), so all these piggy back units actually have to modify the map signal the other way, ie, when the car is at 14.7psi of boost, the piggyback is fooling the ecu into thinking its running say 13psi, so it won't cutout, but now we have the fueling of a 13psi setting, when we are running much more boost than this and thus lean..
Steve, this is why the RR firm you used left your car at 13psi. They probably found they could leave it at that boost, and map the Dastek a little rich, as there was still a little more voltage range on the map sensor left to richen it up (they could run it at nearly 5v). They probably found that 13psi with 15psi's worth of fuel was spot on on your car..
The only way you can get extra fuel on a turbo setup on a piggyback system( and it all says this on the specs) is to use their extra injector drivers that they have built in, but then the issues of placement, getting good position/atomisation etc are a problem..
The other way is to fit much larger injectors, but that involves completely mapping the piggyback unit from afresh, as the whole map is now overrich at every point, but then you have a problem at the other end of the scale.
Getting back to the voltage, imagine your car is at idle or very low load cruising, say 0 - 0.5v on the map sensor, but your larger injectors are overfueling. Now the piggy back could be used to modifiy the signal, so the original ecu sees a lower voltage to lean it out.....but if the sensor is nearly at 0, how can you lower the voltage any more?
You can't, so you end up running rich low down, fouling plugs, poor mpg, more lag and soggy response etc...
Then the other problem, like Ive mentioned before, is the air temp correction on a GTA. Now we all know that on a RR, the inlet air temps are high, and this causes the original ecu to richen up the mixture, and retard the ignition. So when you are mapping the piggyback, you are compensating for this and setting the fuel and ignition up correctly as you want it on the RR...
But then you go out on the road, where there is cooler air, the the fueling isnt richened or ignition retarded by the original ecu, and now your perfect fuel mixture is actually leaner than it was on the RR, and the ignition is now more advanced...
..your thoughts..?
Non Member
594
Thu Nov 17, 2005 5:35 pm
york
peterg wrote:Send Davids post to them then post the answer! Having seen all the posts about this subject I suspect you are alone in thinking your Dastek is doing the job of a programmable ECU. How is it mapping the ignition for starters????
Non Member
3474
Thu Apr 15, 2004 8:10 am
Colchester, Essex
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