modified fuel rail kit???
22 November 2000, 02:53 AM
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In the book "Training WRX", I read about a modified fuel rail kit which is available in Australia.. Does anyone know what this kit consists of and how it works? Also, if anyone can tell me where I can buy this kit, it would be greatly appreciated.
22 November 2000, 01:14 PM
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JonH,
You can get the modified fuel rails from MRT from Australia.I believe the modified rails uses 2 fuel regulators.
I prefer to upgrade fuel injectors and fuel regulator and also fuel pump.This should be sufficient to give your engine an adequate supply of fuel but you need an aftermarket ECU (preferrably that can be adjusted) to control bigger cc injectors.The Japs tuners dont seems to be interested in upgrading fuel rails in the WRX/STi models.
Chan HT
You can get the modified fuel rails from MRT from Australia.I believe the modified rails uses 2 fuel regulators.
I prefer to upgrade fuel injectors and fuel regulator and also fuel pump.This should be sufficient to give your engine an adequate supply of fuel but you need an aftermarket ECU (preferrably that can be adjusted) to control bigger cc injectors.The Japs tuners dont seems to be interested in upgrading fuel rails in the WRX/STi models.
Chan HT
22 November 2000, 03:58 PM
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Chan HT,
Thanks for the help! Actually, I have a STI IV and I'm currently running a larger turbo on the car. As a matter of fact, I already have 550cc injectors and a Skyline GTR fuel pump installed. However, sometimes when I'm in 2rd or 3rd gear, with the engine revving at 5-6K rpm, if I let off the gas and get back on FULL throttle, sometimes there is a hesitation which feels like the injectors are not dumping fuel.
BTW, this happens even with a full tank of fuel.. I read in the "Training WRX" book that there may be a fuel delivery problem to cylinder 2 inherent in the design of the fuel system.. Hopefully, this may solve my problem!
[This message has been edited by JonH (edited 23 November 2000).]
[This message has been edited by JonH (edited 23 November 2000).]
Thanks for the help! Actually, I have a STI IV and I'm currently running a larger turbo on the car. As a matter of fact, I already have 550cc injectors and a Skyline GTR fuel pump installed. However, sometimes when I'm in 2rd or 3rd gear, with the engine revving at 5-6K rpm, if I let off the gas and get back on FULL throttle, sometimes there is a hesitation which feels like the injectors are not dumping fuel.
BTW, this happens even with a full tank of fuel.. I read in the "Training WRX" book that there may be a fuel delivery problem to cylinder 2 inherent in the design of the fuel system.. Hopefully, this may solve my problem!
[This message has been edited by JonH (edited 23 November 2000).]
[This message has been edited by JonH (edited 23 November 2000).]
22 November 2000, 07:14 PM
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Jon,
Personally, I "HATE" the idea of twin regs. Making sure they give identical fuel/pressure, is going to be a pain.
I suspect that the hesitation is not fuel system related. I would check the fuel pressure, and also check the map (I assume it's adjustable).
Our cars a pretty similar, in both mods, and power, but I'm still using the standard 440cc injectors (soon to go
). I have never had a fuel feed problem, and am only now starting to get very high injector %'s, but this only happens under full load, at higher revs. Injector %'s are never a problem under low load (trailing throttle) where on "lift off" you go into vacumm.
Standard fuel pressure is about 2.4bar, but some of us use an adjustable regulator, and increase this to about 3.2bar, but with 550cc injectors I would expect the car to run very rich at idle (until remapped).
On the Possum Link there are "fuel enrichment" zones, just for accelleration, and they make a massive difference.
I think it would be worth running the car with the mapping equipment attached/datalogging, or on a rolling road, to see exactly what is happening.
Mark.
[This message has been edited by R19KET (edited 22 November 2000).]
Personally, I "HATE" the idea of twin regs. Making sure they give identical fuel/pressure, is going to be a pain.
I suspect that the hesitation is not fuel system related. I would check the fuel pressure, and also check the map (I assume it's adjustable).
Our cars a pretty similar, in both mods, and power, but I'm still using the standard 440cc injectors (soon to go
). I have never had a fuel feed problem, and am only now starting to get very high injector %'s, but this only happens under full load, at higher revs. Injector %'s are never a problem under low load (trailing throttle) where on "lift off" you go into vacumm. Standard fuel pressure is about 2.4bar, but some of us use an adjustable regulator, and increase this to about 3.2bar, but with 550cc injectors I would expect the car to run very rich at idle (until remapped).
On the Possum Link there are "fuel enrichment" zones, just for accelleration, and they make a massive difference.
I think it would be worth running the car with the mapping equipment attached/datalogging, or on a rolling road, to see exactly what is happening.
Mark.
[This message has been edited by R19KET (edited 22 November 2000).]
23 November 2000, 04:06 AM
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R19KET,
Unfortunately, I'm situated out in Hong Kong and there are no rolling roads here. I'm using an HKS F-Con V-Pro which is remappable but the writing software is only available to several tuners in Japan. I definitely have enough fuel if I do full throttle runs (for eg. a 1/4 mile time trial) - it is only during the scenario I mentioned above that I have the fuel feed problem.
I did run my setup initally with the stock injectors/fuel pump (BTW, I'm running a TRUST/Greddy TD06-20G turbo kit) and even with a re-mapped ECU, I could not get safe A/F ratios running more than 1bar of boost.
Unfortunately, I'm situated out in Hong Kong and there are no rolling roads here. I'm using an HKS F-Con V-Pro which is remappable but the writing software is only available to several tuners in Japan. I definitely have enough fuel if I do full throttle runs (for eg. a 1/4 mile time trial) - it is only during the scenario I mentioned above that I have the fuel feed problem.
I did run my setup initally with the stock injectors/fuel pump (BTW, I'm running a TRUST/Greddy TD06-20G turbo kit) and even with a re-mapped ECU, I could not get safe A/F ratios running more than 1bar of boost.
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23 November 2000, 05:20 AM
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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by JonH:
<B>R19KET,
Unfortunately, I'm situated out in Hong Kong and there are no rolling roads here. I'm using an HKS F-Con V-Pro which is remappable but the writing software is only available to several tuners in Japan. I definitely have enough fuel if I do full throttle runs (for eg. a 1/4 mile time trial) - it is only during the scenario I mentioned above that I have the fuel feed problem.
I did run my setup initally with the stock injectors/fuel pump (BTW, I'm running a TRUST/Greddy TD06-20G turbo kit) and even with a re-mapped ECU, I could not get safe A/F ratios running more than 1bar of boost. [/quote]
slightly off topic here,
but I was wondering if I can fit any type of larger injector onto the std fuel rail in a MY99??
as I understand, the std injector for my99 is rated 480cc, which is safe for about 280ps at 90% injector duty cycle.
I'm planning to use the Supra fuel pump, and if possible, fitting the std supra fuel injectors as well.(since I can get them quite resonable when compare to HKS ones)
Will the injectors fit?? or what type of modification am I looking at?
thanks
<B>R19KET,
Unfortunately, I'm situated out in Hong Kong and there are no rolling roads here. I'm using an HKS F-Con V-Pro which is remappable but the writing software is only available to several tuners in Japan. I definitely have enough fuel if I do full throttle runs (for eg. a 1/4 mile time trial) - it is only during the scenario I mentioned above that I have the fuel feed problem.
I did run my setup initally with the stock injectors/fuel pump (BTW, I'm running a TRUST/Greddy TD06-20G turbo kit) and even with a re-mapped ECU, I could not get safe A/F ratios running more than 1bar of boost. [/quote]
slightly off topic here,
but I was wondering if I can fit any type of larger injector onto the std fuel rail in a MY99??
as I understand, the std injector for my99 is rated 480cc, which is safe for about 280ps at 90% injector duty cycle.
I'm planning to use the Supra fuel pump, and if possible, fitting the std supra fuel injectors as well.(since I can get them quite resonable when compare to HKS ones)
Will the injectors fit?? or what type of modification am I looking at?
thanks
23 November 2000, 09:28 AM
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Jon,
480cc's would be good for about 350bhp, with the correct set up.
97/98 STi's came with 440cc's as stock, and would happily do about 320bhp.
Mark.
480cc's would be good for about 350bhp, with the correct set up.
97/98 STi's came with 440cc's as stock, and would happily do about 320bhp.
Mark.
23 November 2000, 01:00 PM
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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by R19KET:
<B>Jon,
480cc's would be good for about 350bhp, with the correct set up.
97/98 STi's came with 440cc's as stock, and would happily do about 320bhp.
Mark.[/quote]
Mark,
are you sure about this??
The basic formula for calculating fuel requirements is (no. of cylinders x injector flow rate) / 6.75, this equals to about a 90% duty cycle.
so for a car with 4 cylinders and 480 cc/min injectors, would have enough fuel for (4 x 480) / 6.75 = 284.44 hp.
since I don't think it's good idea running the injectors static all the time, I like some safe margin. so with the target of 320, I think you are safer at 550cc...
<B>Jon,
480cc's would be good for about 350bhp, with the correct set up.
97/98 STi's came with 440cc's as stock, and would happily do about 320bhp.
Mark.[/quote]
Mark,
are you sure about this??
The basic formula for calculating fuel requirements is (no. of cylinders x injector flow rate) / 6.75, this equals to about a 90% duty cycle.
so for a car with 4 cylinders and 480 cc/min injectors, would have enough fuel for (4 x 480) / 6.75 = 284.44 hp.
since I don't think it's good idea running the injectors static all the time, I like some safe margin. so with the target of 320, I think you are safer at 550cc...
23 November 2000, 01:38 PM
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JonJon,
I have seen MY99 WRX wagon Jap spec rated at 250hp and has yellow coloured injectors but these injectors are different from MY98 STi injectors.The Jap spec MY99 injector has 4 spray nozzles holes at the tip as opposed to one spray nozzle hole of the MY98 STi injector.The MY99 fuel rail is also different from MY98.
JonH,
I agree with Mark,try increse your fuel pressure using an adjustable fuel pressure regulator.Upping the fuel pressure will improve throttle response and fuel pressure will increase about 1.5 times the second you full throttle the pedal thus ensuring enough fuel supply to your engine and possible no hesistation.
Does the GTR fuel pump a direct bolt on to our Rex??
I was also told that our Rex fuel filter is quite restrictive.
Hope this helps.
I have seen MY99 WRX wagon Jap spec rated at 250hp and has yellow coloured injectors but these injectors are different from MY98 STi injectors.The Jap spec MY99 injector has 4 spray nozzles holes at the tip as opposed to one spray nozzle hole of the MY98 STi injector.The MY99 fuel rail is also different from MY98.
JonH,
I agree with Mark,try increse your fuel pressure using an adjustable fuel pressure regulator.Upping the fuel pressure will improve throttle response and fuel pressure will increase about 1.5 times the second you full throttle the pedal thus ensuring enough fuel supply to your engine and possible no hesistation.
Does the GTR fuel pump a direct bolt on to our Rex??
I was also told that our Rex fuel filter is quite restrictive.
Hope this helps.
24 November 2000, 02:28 AM
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Chan,
from what I've gathered, all the Phase II engine has injectors that's multi nozzles design. and they will not fit the Phase I fuel rails.
but my question was that will I be able to fit any aftermarket injectors in the fuel rail? or is there a set of standard of design that I can follow?? I really want to get the supra injectors since they are 550cc and CHEAP.
I'm not sure about the GTR fuel pump, but the Supra TT fuel pump will fit w/o mods, and has higher capacity than the gtr pump.
one thing to concern is the NOISE that the gtr pump generate. my buddy fitted one and the noise was so loud that's unbearable for me.
also, many people will argue against using a regulator to bump up the fuel pressure, this is not the proper way to get more fuel. Use a better fuel pump instead.
as to the fuel filter, change them OFTEN.
from what I've gathered, all the Phase II engine has injectors that's multi nozzles design. and they will not fit the Phase I fuel rails.
but my question was that will I be able to fit any aftermarket injectors in the fuel rail? or is there a set of standard of design that I can follow?? I really want to get the supra injectors since they are 550cc and CHEAP.
I'm not sure about the GTR fuel pump, but the Supra TT fuel pump will fit w/o mods, and has higher capacity than the gtr pump.
one thing to concern is the NOISE that the gtr pump generate. my buddy fitted one and the noise was so loud that's unbearable for me.
also, many people will argue against using a regulator to bump up the fuel pressure, this is not the proper way to get more fuel. Use a better fuel pump instead.
as to the fuel filter, change them OFTEN.
24 November 2000, 08:54 AM
#13
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Flow thro'the injector is proportional to the pressure drop across it so increasing the fuel pressure will give more flow but ... the pump rating may not allow enough to be delivered to take advantage of that so thats when the pump needs to be uprated, increasing flow without increasing pressure will not do much except move the fuel around the car faster. Standard reg give approx a 1 bar differential across the injector. Fitting an adjustable aftermarket reg will enable the differential to be increased.
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