Discussion
Am I right to say that a very common way to gain bhp, especially with japanese turbo cars, is to fit larger injectors/raise fuel pressure and basically crudely overfuel to match increased demands/boost and not detonate.
I know a SLIGHTLY richer than stoichometric fuel/air mix gains more power, but just how much of a compromise is this in comparison to proper fuel remapping?
I know a SLIGHTLY richer than stoichometric fuel/air mix gains more power, but just how much of a compromise is this in comparison to proper fuel remapping?
Hmmmmmmm so many questions in one..
Jap cars are no different to any other with respect to raising boost/fuel levels etc.
The use of larger injectors allows more fuel for the same open open duration at the same fuel pressure.
But more fuel on its own is useless without the extra air to mix it with.
Higher boost levels can be compensated for by most management systems (to a degree) but you have to be a little careful about "too much".
Basically if you overdo it with just turning up the boost, the injectors will run out of capacity and cause a lean condition, not good at full throttle and full load.
The management can compensate with fuelling up to a finite point before the injectors run out of flow capacity, by lengthening the duration of the "on" time of the injector (duty cycle) but if your not careful here, the injectors could end up with a 100% duty cycle, leading to a burn out of an injector.
Hence the need for larger injectors, if you gonna do the job right.
The other way is to raise the fuel pressure to get more injector flow for the same open time.
Really, the best, safest way is to get the new engine set up with the components it will run with on the dyno, and get it mapped that way.
Ive done a few experiments on the GT4 which has all manner of safety overides to prevent us modders from upping the boost at will.
Basically i managed to raise the boost from 7psi (factory standard) to 13 psi.
Goes like a rocket but its not sustainable, due to intercooler inefficiency and topping out on injector flow, although i have changed the pump to get higher fuel pressures later on.
Hope some of this is helpful.
Jap cars are no different to any other with respect to raising boost/fuel levels etc.
The use of larger injectors allows more fuel for the same open open duration at the same fuel pressure.
But more fuel on its own is useless without the extra air to mix it with.
Higher boost levels can be compensated for by most management systems (to a degree) but you have to be a little careful about "too much".
Basically if you overdo it with just turning up the boost, the injectors will run out of capacity and cause a lean condition, not good at full throttle and full load.
The management can compensate with fuelling up to a finite point before the injectors run out of flow capacity, by lengthening the duration of the "on" time of the injector (duty cycle) but if your not careful here, the injectors could end up with a 100% duty cycle, leading to a burn out of an injector.
Hence the need for larger injectors, if you gonna do the job right.
The other way is to raise the fuel pressure to get more injector flow for the same open time.
Really, the best, safest way is to get the new engine set up with the components it will run with on the dyno, and get it mapped that way.
Ive done a few experiments on the GT4 which has all manner of safety overides to prevent us modders from upping the boost at will.
Basically i managed to raise the boost from 7psi (factory standard) to 13 psi.
Goes like a rocket but its not sustainable, due to intercooler inefficiency and topping out on injector flow, although i have changed the pump to get higher fuel pressures later on.
Hope some of this is helpful.
More of curiosity really. I've just noticed that a lot of DIY modding on turbos is to wack in an enormous turbo, run boost at 25psi and chuck in loads of fuel (larger injectors, no remap) to prevent leanout. Overfuelling? Yes but apparently flames coming out of your tailpipe on overrun is a good thing apparently.
I'm going to be spending rather a lot of time and money in the presence of a lumenition EMS for my car. I just wondered just how much better a proper remap is over using OE engine management and kludging higher fuel supply across the board.
I'm going to be spending rather a lot of time and money in the presence of a lumenition EMS for my car. I just wondered just how much better a proper remap is over using OE engine management and kludging higher fuel supply across the board.
Flames coming out of the exhaust......hmmm you not having a Max moment there mate? lololol
A properly mapped system as opposed to attempting to bypass the safety features is the best way to go for sure.
All the parameters will be correct, so youll have peace of mind when you boot it too...last thing a PHer wants is his valves spilling outa the tailpipe...lol you know it makes sense!
A properly mapped system as opposed to attempting to bypass the safety features is the best way to go for sure.
All the parameters will be correct, so youll have peace of mind when you boot it too...last thing a PHer wants is his valves spilling outa the tailpipe...lol you know it makes sense!
A slightly rich ~12:1 mixture yields more power, but richer still leads to stumbling, plug and chamber fouling and generally less power.
Therefore a properly matched and mapped fuelling supply will always give better results. Its not just a case of wasting a bit of fuel 'out the tailpipe'.
Therefore a properly matched and mapped fuelling supply will always give better results. Its not just a case of wasting a bit of fuel 'out the tailpipe'.
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