Originally Posted by
oldford
You are contradicting your self. Only the 2nd statement is correct. When running closed loop there's only 1 possible setting for the lower half of the fuel map.
I had a customer that was running one of my stage 1 chips in his 2wd Sierra.
I claimed 261 bhp and 360 Nm for that, which was measured on a very professional engine bench. The specific fuel usage was measured at 320 grams/Kw at WOT, more than enough, maybe even a little bit too much, so I saw no problems with the injectors.
At that time I had no stage 2 available and the customer ordered a 280 bhp set from the UK.
803's, 3-bar map sensor, the works. He drove around with it for a couple of days and then went back to my stage 1 chip. His explanation was that the car was simply faster with my chip with the added advantage of being more fuel efficient.
No im not mate,You just dont understand.
On a big turbo it wont be making boost where a smaller T3 will be. So there is less fuel in the map there.
Compare a T3 fuel map with one from a T4 and you will see the fuel map is totally different (As you would expect!).
The low down part of a T4 map has much less fuel in it as the car is always off boost down there because the turbo is more lathargic, where as the T3 wants to make boost early.
The breakpoints are even shifted around low down as the T4 map will not need as many load sites, and can make better use of them higher up in the table.
Scenario 1 was a swap to a bigger turbo.(they will have less fuel low down in the map, thats a fact Because the turbo makes its boost Higher!)
Scenario 2 was with both cars on a T3. (running bigger injectors doesnt mean it will use more fuel at cruise and idle, infact it will be the same if the same target AFR is used.)
The chip you used must have been terible then, as its almost impossible to make the same engine, with the same turbocharger slower by allowing it to run more boost, All i can say is the fuelling must have been horrific, as a good 803s T3 car is actually pretty fast, and would kill any stage 1 car as you would imagen because it can hold higher boost levels. Combined with the way the T3 makes boost really early and low down, they are a great road car.
But hey, what do i know, i do this and map these cars for a living.
From reading your replies, it sounds like you have never been in a T4 powered car, to see they are off boost far more often than a little T3.
I wasnt saying your original comment about more power meaning more fuel was wrong, im just saying it totally depends how the car is used and driven, so its not as clear cut as you made it out to be.