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Discussion Starter · #1 ·
I have been doing some research and I want someone to double check my homework.

A little bakground.

I purchased a 94 TT with HKS twins and the following fuel mods.

- 2 Walboro in-tank fuel pumps running 12V on individuel relays straight from the battery
- Paxton fule filter.
- (-8) Line to the fueler and from teh fuel filter to a "Y" fitting.
- (-6) Lines from the "Y" split to both ends of the Power House Fuel rail.
- (-6) line from the middle of the fuel rail to the Aeromitve FPR.
- 8900cc RC injectors.
- EMS G-force ECU with MAP ECU

Currently, I have changed my turbo setup to a 76GTS and my power goal is 1000rwhp with a small shot of NOS.

Aside from the injectors, I am chooing 1600cc RC injectors to be manage by a HKS FCON-VPRO, what else sould I add in or change to my fuel system.

Would I need a 3rd Walboro pump for 1000rwhp?
 

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from a safety I would.

Each of the walbro is good to a bit higher than 600 hp at the CRANK! Take the loss of the drive train and you will be teetering one the edge of a dead motor ;)
 

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Alpine Hardtopper
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Yes, a 3rd Walbro would be good just for safety measure. You'll probably want to consider wiring them differently though. If you have all three come on with the key, that's a LOT of fuel that has to go through the regulator. A lot of people like to trigger the 2nd (and 3rd) relays based off boost pressure or throttle position. You can certainly run off one pump while idling ang cruising. But you'll want all three going when you get out near 1000 hp.

I guess one thing you could do before investing on the 3rd Walbro setup would be to monitor fuel pressure on your current system. You could add a pressure sensor and log that data on your FCON. If the system keeps up fine, then you won't have to worry about the 3rd pump.

So, did you already find a new home for the HKS twins?
 

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Alpine Hardtopper
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I've heard about a number of different ways it can be done. If you're running a programmable ECU, you can use one of the outputs to trigger the relay. It can be set to turn on (or ground relay to engage pump) when boost pressure is over 5 psi, or when throttle position is over 75%, or both. I know a lot of Supra owners with AEM EMS's are running this way.

If you don't have an ECU to program, you can do it with boost switches as well. Using a switch that closes at a set pressure (something over atmosphere, but less than what your single pump can supply easily), just use that boost switch to turn on the relay for the 2nd (or 3rd) pump.

Also, there's a big safety issue in running the pumps directly off the key (in case of accident). I believe a number of people are having the output of the stock fuel controller engage the relay for the fuel pumps (if they're being run with a relay direct to the battery.

Another alternative I didn't think about until just now is the option of over-volting the 2 Walbro fuel pumps. I thought one place did testing with several pumps up to the 19V range. Could be that getting a DC-DC converter and running 2 Walbro pumps in the 16-18V range would still be a very safe margin for 1000 rwhp.

I still haven't decided what route I'm going for fuel system. Lots of people complain about the noise of the Walbro pumps. I'm not looking for high HP...something in the mid 500 rwhp with great track manors is my goal. But I'm debating between 2 TT pumps or just getting one of the Skyline pumps. If I go with the 2 TT pumps, I'll definitely stage one so it isn't running all the time.
 

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Others have been covering the electrical changes that you need to make. I will cover some of the parts/mechanical pieces that need to be addressed.

First off, you have a -8 as a feed line and -6's to the rail. I would start by bumping that diameter up. A -10 feed into two dash -8's or -10's would ensure that you are not bottlenecking the situation. I don't know what rail you are using so that may pose further issues. Someone can correct me if I'm wrong, but the HKS rail is -6 inlets? So a different rail may be in order.

Secondly, you are desiring to using 1600cc injectors???? Why the overkill?

Other than those items, I don't see anything else to address.
 

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^^Be careful of what this guy has to say fellas, I'm not sure that he has much experience with supras. . .





:p
 

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:1poke: Hahaha fauker!! :bigthumb:

Well....in that case..... :) We'll just have to see how well you're fuel system holds up after I'm done ripping it apart!!!!! :1poke:
 

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Discussion Starter · #9 ·
NSANITY said:
Others have been covering the electrical changes that you need to make. I will cover some of the parts/mechanical pieces that need to be addressed.

First off, you have a -8 as a feed line and -6's to the rail. I would start by bumping that diameter up. A -10 feed into two dash -8's or -10's would ensure that you are not bottlenecking the situation. I don't know what rail you are using so that may pose further issues. Someone can correct me if I'm wrong, but the HKS rail is -6 inlets? So a different rail may be in order.

Secondly, you are desiring to using 1600cc injectors???? Why the overkill?

Other than those items, I don't see anything else to address.

The price between 1600cc injectors and 1200cc injectors are so small, that if I even wanted morepower and change turo setup, then I woudl not have to change injectors. As I have heard with the HKS-FCON, the only time the sytem needs to be reutned is if you change injector sizes. This is coming from MR> Obiwan himslef. Now, I might have a 1000rwhp goal now, but if I decied to go T6 with a GT47-80, then I woudl already have the injectors and fuel system in place. Ther eis no need for a Obiwan retune as he is the only one that comes to Dallas enough to tune teh HKS FCON.

I have PHR fuel rail which I htink is only limted to -6. I will have to re-investigate this. I will look at staggering the two fuel pumps. Currentl I have them come one full blast at 12V from start up by passing the fuel ECU. I will use the high voltage trigger to turn on the second pump, for those high boost applications for now. When teh HKS FCON pro goes in, then I will setup the 3rd pump on this as I will use it as a piggy back unit....I still want A/C managemnt from teh stock ECU.
 

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Discussion Starter · #10 · (Edited)
cord4530 said:
Yes, a 3rd Walbro would be good just for safety measure. You'll probably want to consider wiring them differently though. If you have all three come on with the key, that's a LOT of fuel that has to go through the regulator. A lot of people like to trigger the 2nd (and 3rd) relays based off boost pressure or throttle position. You can certainly run off one pump while idling ang cruising. But you'll want all three going when you get out near 1000 hp.

I guess one thing you could do before investing on the 3rd Walbro setup would be to monitor fuel pressure on your current system. You could add a pressure sensor and log that data on your FCON. If the system keeps up fine, then you won't have to worry about the 3rd pump.

So, did you already find a new home for the HKS twins?

The twins ahve a new home already. THey were great, but I wanted more power and I find the 76GTS to be my new drug. But who knows how long that will be. The GT42-76 and the GT47-80 might be my new drug next year. :)
 

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It's great that you're planning ahead for more power upgrades. The only bad thing I've heard about using really large injectors is potential idle problems. It's just really hard to meter small amounts of fuel with any precision when using super large injectors. But if you're not using the car to drive through city traffic every day, the idle may not bother you at all.

On the fuel rail side, the current PHR rail has an AN -10 internal diameter. It could be that your rail has a large inner diameter, but with AN -6 fittings on each end. Or it could be that the larger fuel rail is a new offering from them, and earlier ones had a smaller size. If you do have their larger one, it's supposed to support up to 1400 crank hp.

Sounds like a great plan for control of the three pumps.
 

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I would have to agree on the above post. However, I don't know how well the HKS FCON works in relation to everyday driveability in high horspower applications. I do know that the AEM is capable of taking care of this task, but that really doesn't help you for obvious reasons.
 

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Discussion Starter · #13 ·
Hmmm, maybe Mr. Henderson can chime in on that one. He's pushing over 1000rwhp on his stroker and has no issues with idle, stop and go traffic or cold start.
 

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Well, I have the F-CON V-Pro as everyone knows, eight (8) 1000 cc Denso injectors driven full time and two OEM Denso fuel pumps. I also believe it has, for the money, unmatched capability in everyday driving situations as my car and other V-Pro equipped cars continue to demonstrate. With this set-up, I have made over 1100 wheel. I have yet to see a street car with 1600 cc injectors idle well, start easily when warm or deal with normal, in my case, SoCali traffic conditions, including lots of bumper to bumper. I have also yet to see a street car need 1600 cc injectors. My set-up, or something similar will work for most situations and, at most, I would not go past 1200 cc injectors.

As big a fan as I am of the V-Pro, I do not believe it will be able to effectively handle 1600 cc injectors, similar to the AEM, on a street-biased car. Obiwan, of course, would know more about this than me, but I'm not aware of a V-Pro equipped car running 1600 cc injectors on the street. As implied, if 1000 wheel is your goal, 1600 cc injectors are not necessary.

With my set-up, and at a steady 80-85 mph on the way to Vegas last year, I got a tad over 24 mpg, about as good as it gets for cars making as much power as ours.

Ken.
 

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Discussion Starter · #15 · (Edited)
KenHenderson said:
Well, I have the F-CON V-Pro as everyone knows, eight (8) 1000 cc Denso injectors driven full time and two OEM Denso fuel pumps. I also believe it has, for the money, unmatched capability in everyday driving situations as my car and other V-Pro equipped cars continue to demonstrate. With this set-up, I have made over 1100 wheel. I have yet to see a street car with 1600 cc injectors idle well, start easily when warm or deal with normal, in my case, SoCali traffic conditions, including lots of bumper to bumper. I have also yet to see a street car need 1600 cc injectors. My set-up, or something similar will work for most situations and, at most, I would not go past 1200 cc injectors.

As big a fan as I am of the V-Pro, I do not believe it will be able to effectively handle 1600 cc injectors, similar to the AEM, on a street-biased car. Obiwan, of course, would know more about this than me, but I'm not aware of a V-Pro equipped car running 1600 cc injectors on the street. As implied, if 1000 wheel is your goal, 1600 cc injectors are not necessary.

With my set-up, and at a steady 80-85 mph on the way to Vegas last year, I got a tad over 24 mpg, about as good as it gets for cars making as much power as ours.

Ken.

Ken, now I am confused. The 1000cc injectors does break the 80% duty cycle, 1cc pr crank HP rule of thumb stated by RC engineering. Will the 1000cc x 8 equate to or more than 1200cc x 6? Although I have heard of people running the injectors pas this rule of thumb. I know you probably don't drive your car with 1100rwhp on the street much. I'm building a street/9s track hybrid here. This is why I want to go HKS FCON. I did recently purchase some 1000cc injectors but wasn't going to stick with them becuase of the 80% duty cycle rule of thumb. Now I do live in Dallas that is only 450-750ft above sea level which would a minor affect on the fuel system.

Would 1200cc injectors be a better choice then. Severely rounding off calculations, this ideally would put me at 1000rwhp with the 80% duty cycle. I hear from a lot of poeple that 1cc per hp, then I hear 1cc per crank hp, then I read from RC engineering calculations 1cc @ 180% duty cycle per crank hp.

So, which way do I go? What type of fuel rail are you using and I really don't understand how 8 injectors operate on a 6 cylinder car.

Thanks for everyones input.
 

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donkeypunch,

Clear you PM so I can send you a couple of pics. Thanks.

Ken.
 

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donkeypunch said:
Ken, now I am confused. The 1000cc injectors does break the 80% duty cycle, 1cc pr crank HP rule of thumb stated by RC engineering. Will the 1000cc x 8 equate to or more than 1200cc x 6? Although I have heard of people running the injectors pas this rule of thumb. I know you probably don't drive your car with 1100rwhp on the street much. I'm building a street/9s track hybrid here. This is why I want to go HKS FCON. I did recently purchase some 1000cc injectors but wasn't going to stick with them becuase of the 80% duty cycle rule of thumb. Now I do live in Dallas that is only 450-750ft above sea level which would a minor affect on the fuel system.

Would 1200cc injectors be a better choice then. Severely rounding off calculations, this ideally would put me at 1000rwhp with the 80% duty cycle. I hear from a lot of poeple that 1cc per hp, then I hear 1cc per crank hp, then I read from RC engineering calculations 1cc @ 180% duty cycle per crank hp.

So, which way do I go? What type of fuel rail are you using and I really don't understand how 8 injectors operate on a 6 cylinder car.

Thanks for everyones input.

If you want to closely adhere to the 80% duty cycle standard, and want to make 1000+wheel reliably, 1000 cc/min will not do it for you. Others have routinely ran 80-90% duty cycle with no apparent ill effects. I'm not recommending this. I'm just saying it has been done rather frequently.

In my case, we ran out of injector at 2.18 kg/cm^2 (30.9 psi) and 1,031 whp, so we installed an HKS mini fuel rail that accommodated two additional 1000 cc injectors and run them full time with the F-CON V-Pro. Now, theoretically, I have 1333 cc/min per cylinder. Some have argued additional injectors compromise your cylinder to cylinder fuel distribution and that is probably correct in some instances. In my case, it is important to note that cylinder to cylinder balance is a strength of the VeilSide intake and where we located the additional injectors, I feel, provides ample opportunity for fuel atomization and equal distribution. Even if I'm wrong and they're right, I know I am getting at least 1200 cc/min per cylinder.

The beauty of the eight 1000 cc Denso injectors is that, driven full time, you can go easier on the duty cycle, something of obvious importance to you, and retain excellent idle quality and all around driveability. For my money, the Denso 1000s, marketed under the Blitz name, are the best 1000 cc injectors available and also have the best idle quality which anyone having heard my car idle will attest to.

Check out post #60, IIRC, in Rsky's thread, a car that just made 1026 whp with an HKS 3.4L stroker and twin HKS 3037S turbos: http://www.supraforums.com/forum/showthread.php?t=364086&page=3. His set-up is the same as mine. I have a couple of pics I'd like to email you of my set-up if you want, as I have never been successful posting pics on SF. Hope this helps.

I have a VeilSide fuel rail, btw.

Ken.
 

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BTW, what BSFC assumption are you using?

Ken.
 

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FYI, The HKS rail is VERY large internally. The fittings that come with the kit are -6AN fittings. These fittings are basically a -6AN to Metric 16X1.5mm. Even though totally unnecessary, you can purchase -8AN to metric 16X1.5mm fittings from Earl's and install them onto your HKS rail and convert it to a -8AN. The HKs rail also has a 1/4" NPT port closer to the #6 injector that can be used to either install a fuel pressure guage and/or a fuel pulsation damper. You can even use this port for return with dual end inlets by using the correct adapter.

IMO, three walbros keep the fuel sender assembly very crowded. If your goal is around 750 WHP then 2 walbros are more than sufficient. If its about 1000 then 2 OEM denso pumps will do just fine. If you're shooting for more than that you really should be investing in 2 inline bosch race pumps or 2 aeromotive A1000 pumps.

Use the proper electronics to control these pumps or else your fuel system return will be over taxed and pressure will rise uncontrollably.

-Joe
 
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