Supra Forums banner

1 - 20 of 23 Posts

·
Registered
Joined
·
342 Posts
Discussion Starter #1
for those who installed your own fuel system, how does your fuel system laid out? Direct...with the fuel feeding line on one end of the rail and the FPR on the other end or did your make a loop using a couple of tees? Is one way better over the other ?Thanks.
 

·
Registered
Joined
·
2,124 Posts
I'm getting ready to do mine. Either dual pumps in the tank or the big external aeromotive. -8 line coming out of the tank from a 90 degree -8 bulkhead connector to an aeromotive filter. Then up to the rail. Probably the HKS with 720cc injectors. -6 out the other end to an aeromotive fuel pressure regulator then -6 either all the way back or I might connect into the stock feed line at the factory fuel filter to save on some line and install time. This is speculation, but I don't see the need of feeding both ends and complicating the system unless you are going for 800+. I've seen singles at the track running 10s routing the fuel the normal way. In one end, out the other. I'm sticking to that. My only problem so far has been finding the right an connectors. HKS rail uses -6 and I want to connect -8. Stillen is trying to get a reducer from Goodridge so hopefully they will come through. I'm also doing this in stages and will connect the -8 to the stock rail for a while. Trying to get a -8 banjo fitting for that. Again Goodridge. Everything else you can get from Aeroquip, Russels or Earls. I'm buying most of my stuff from summit racing.
 
J

·
Guest
Joined
·
0 Posts
Hmm..

With a HKS Fuel rail, does anyone know if there is a fitting that goes to a AN-8? I'm looking at the Japanese manual, and they say the part number is 90445-065100, but HKS USA has no clue.

Anyone else using the HKS Fuel Rail with a AN8 Fitting attached to it without a reducer? If yes, Where did you get the AN8 to M16 connector?

j0.
 

·
Registered
Joined
·
342 Posts
Discussion Starter #5
hey guys, do you know if the -8 bulkhead will fit without clearance problems? I am running the Y in the tank using NOS' -8 to 2x-6. I think you get better fuel flow with the Y instead of the Tee.
 

·
Registered
Joined
·
2,913 Posts
I fed each end of the SP rail with a -6 AN

line, one from each in-tank pump. IMO, nothing larger than -6 AN is called for unless you're going to be making more than 1000 RWHP (the smaller-than--6 factory line supplies enough fuel for more than 500 RWHP, so why would you need more than 2 -6 lines to supply fuel for, say, 800 RWHP?). IMO, larger than -6 may even be a disadvantage because upon hard acceleration you have all that extra fuel weight in the line that must be accelerated. It's pressing backwards toward the pumps and could serve to reduce fuel pressure at the injectors. Not a good thing.

I installed a center-rail return on the SP rail. From the center return a -6 line goes to the Aeromotive regulator, then from the regulator to a fuel cooler mounted behind the driver's side turn signal, and from the cooler back to the tank.

Even though a lot of successful installers have done it, I don't like the idea of using Ts at the rail ends. If you do it that way, once the fuel goes into the rail it stays there until it's injected into the engine. I have no proof that it's a disadvantage on the typical Supra to inject high temperature fuel, but I know that certain fuel injected race cars have been proven to make more power with fuel from a cool can (containing ice) versus "engine ambient" temperature fuel. With my setup, fuel is constantly flowing through the rail and out through the cooler, so it should be a bit lower in temperature.

Steve
 

·
Registered
Joined
·
54 Posts
I tried getting the fitting from HKS as well... And found them to be equally clueless. You could probably retap the hole with 3/8NPT(I think thats the correct size), but I'm not sure how good of seal you'd get) or you could do what I did. Take it down to a good machine/fabrication shop and have them weld a -8 on the feed(rear) end of the rail.

I actually have -8 all the way to the regulator and a -6 return. If I ever put nitrous on the car, I'll feed it from the regulator and thought the more flow I could get the better.... But in all hosesty, its overkill and if(actually, I'm doing another car in the near future) I ever do it again, I'll use -6 to the regulator.

The -8 bulkhead out of the tank will clear,but you'll need to put a slight dent in the cover for clearance purposes.

I've got pics of my fuel system at www.wotm.com under their racing pages. Mines the second car on the page and has a link to my fuel install(sorry its not too detailed, it was an afterthought).
 

·
Registered
Joined
·
342 Posts
Discussion Starter #8
Billy, do you have the wiring diagram for attaching the second fuel pump? Which wire did you use to the relay? Did you attached a Resistor inline with the signal before the relay? Thanks.
 

·
Registered
Joined
·
54 Posts
I just used the power wire going to the stock pump to trigger the relay to the second pump. Had to run a power wire from the battery to the back of the car to power the second pump as well...

The relay I used triggers at 7volts or higher, so it turns on when the stock pump wiring gets energized. I did it this way so one runs at 12v and the other on the factory 9/12v. One interesting thing, the Walbro's I use consume a lot less current than the stockers.... so it may be possible to run both off the stock feed line, but I wouldn't recommend it.
 

·
Registered
Joined
·
2,124 Posts
Thanks for the link turbomkiv.

On the racerpartswholesale page there is a -8 ml to 16mm x 1.5 if that's the correct size of the HKS hole. I'm still trying to get the goodridge -6 fml to -8 ml fitting. Stillen didn't call me today like they said and were hesitant to help in the beginning. If anyone knows of a goodridge dealer let me know. I've got a list so I will randomly go thru it until someone can get me these fittings.

Anyone know the thread size of the stock rail? I've heard 14mm x 1.25 but this size is almost nonexistant.

This has turned into a big pain in the ass, but when I ad it up I'm at about $1700 compared to $2300 if you bought everything as a kit.
 

·
Registered
Joined
·
54 Posts
You can get the fitting for the factory rail through any Earl's distributor. I usually go through www.amstreetrod.com

P/N 991945

Its a Dellorto/Solex/Mikuni 6AN adapter. 12x1.25mm

You can also use a 90 degree hose end that screws right on, but its a bit pricey... But you have to buy a 90 anyway....

P/N 849091
 

·
Registered
Joined
·
2,124 Posts
Thanks Billy. I've just about have everything figured out for what I need except for connecting -6 to the factory fitting of the stock fuel filter going back to the tank. It will serve as my return.

I believe I have found the adapter for connecting -6 to -8. It's a -6 female to -8 male. Made by only goodridge. I ordered it from racesearch.com $22 but I need it. It's not on their web site. Got to call and specail order it. Backordered until the 31st.

With the connector info Billy gave me I'll be able to temporarily connect -8 to the factory rail, then I'll be able to connect the -8 to the HKS rail which is -6 once I order that. Problem solved. Just hope they ship the right part.

Thanks for everyones help. I've been trying to figure everything out for over a week now.
 

·
Senior Member
Joined
·
462 Posts
Supra400khptt: Please post your recipe of components and sources/contact information when you've completed the fuel system kit!!!

I would appreciate it...maybe others would too!

:D
 

·
Registered
Joined
·
54 Posts
I'm not sure how you'd go about using the factory feed as a return. You could buy the rail adapter and run a -6 hose, but you'd be flowing the fuel through the filter backwards.

I would assume since the fuel is at low pressure after the regulator, you could simply hose clamp a -6 line to the stock feed(flare it a bit so the hose stays on). It shouldn't blow off...

I ran a full 3/8" return line on my car. I feel a lot more comfortable doing this than using the stock feed.... Plus, if you use the stock feed, you will need to figure a way to get the fuel back in the tank since you'll need that space for the bulkhead fitting above the pumps(if you use the straightest path).

One last thing that I've mentioned before..... DON'T FORGET TO HOOK THE RETURN TO THE HOSE IN THE TANK. This will keep the pumps covered with fuel as was designed by Toyota.
 

·
More torque than you
Joined
·
120 Posts
I advise against using Aeromitive pumps. I was stranded on the way to Kansas City last year because the year old Aeromotive pump quit pumping. I was lucky because I was driving with friends who had a trailer. I know of at least 2 other people who have had this problem. When you install the 90 deg bulkhead fitting you will not be able to run the tank all the way down, you will have to remove or modify the metal fuel tank guard. You will be annoyed by the noise even if you use the supplied mount with rubber insulator.
Instead use 2 Walbro 255ltr/hr high-pressure pumps. You can get these for about 115 bucks each. These high-pressure units are made to still flow good numbers at 80+psi of fuel pressure. Additional benefits are that they are quieter, you can run the tank past the E mark, they will not be exposed to the elements, and if one fails you can still drive your car home. It's also easier to run a -6 line and you can mount a -6 filter right next to the stocker.
Whichever route you go made sure you run a dedicator fused power supply for the pumps. You can use the ECU trigger wire to fire the relay and make sure you do the 12volt fuel pump mod.
I have been running the twins for 4 months now in my daily driven supra and have had the gas below the E mark without any problems.
Good luck
 

·
Registered
Joined
·
54 Posts
Max, I totally agree with you on the pump situation and can also support the statement that you can run to the E and below without fuel starvation.

I do however, have a slightly different opinion on the 12v mod/wiring. Its OK to run one walbro on the 9/12 and the other at 12 all the time. I've put 10k plus on the car like this. One advantage is that the pumps only run when the motor does, unlike the 12v mod....

One line is definately easier to run, but I prefer it to be a single -8 feed and a -6 return(or opt for the stock feed as a return). I'm not sure if the stock return is big enough for the twin walbro's, but it could be. Anybody have experience with this? I know its fine with an HKS pump.
 

·
More torque than you
Joined
·
120 Posts
The reason why I do the 12 volt mod is I don’t give a vac signal to that sensor that controls the voltage switch. I just plug it in and zip tie it below the fuel rail. Keeps the manifold nice and clean this way. The ID of the stock feed line is about the size of a dash 6 line. If you can run 500rwhp on the stock line, adding another line that size is more than adequate for a car making less than 850-900crank HP. Plus the Walbro pump have more volume at higher pressures where you really need it. I have not had a problem using the stock return line either with the Aeromotive or the Walbros. I did though enlarged the return orifice in the Paxton regulator to ensure that it can support the flow.
 

·
Registered
Joined
·
2,913 Posts
I would be very careful about driving the car under boost when the fuel level is low. When my gauge indicates "E", the fuel level in the tank is about a half-inch above the pumps intakes (with the pumps mounted at stock height, which is pretty much on the bottom of the little plastic chamber that surrounds the pumps). It seems to me that a bit of sloshing from hard acceleration is all that would be required to starve the pumps of fuel. I always keep AT LEAST an eighth of a tank of fuel, else I never boost more than a few PSI.

Steve
 

·
Registered
Joined
·
54 Posts
Thanks for the info Max.

Boost Junkie, the fuel pumps are fully submerged under almost all circumstances because the fuel is returned to the 'baffle' in the tank. It will run nearly dry before the level drops too much.

I know one car that when built(not naming the builder), didn't use the 'return' hose to the baffle. The car would have issues below a 1/4 tank. After connecting the hose, all was good even after the fuel light turned on...

I've personally run full passes with the tank reading on E. I monitored fuel pressure very closely and there really aren't any issues as far as I can see.
 
1 - 20 of 23 Posts
Top