Taz_Rx Posted January 14, 2008 Report Share Posted January 14, 2008 Just did this drawing for another forum member, thought it may be of use for others. Mods - Is this suitable for a sticky!? Diagram shows how to convert your previously carby car for EFI conversion, or also for a rising rate carby turbo fuel set up. As mentioned on the diagram, the return line from the engine bay can go directly back into the tank, or back into the surge tank. For the carby turbo setup, pretty much any EFI pressure pump will do the job (except intank pumps*). However all of the pressure and flow they make is not required for the carby. This can be succesfully halved by running a ballist resistor (ceramic box next to coil) to drop the voltage to 6v. *Most in tank pumps have a releif valve that will let fuel exit through the body of the pump. If you used one of these setup in the above diagram, it would spray fuel all through your boot!!! Link to comment Share on other sites More sharing options...
flat out Posted January 14, 2008 Report Share Posted January 14, 2008 hey si your inbox is full up! Link to comment Share on other sites More sharing options...
Davros El Davros Posted January 14, 2008 Report Share Posted January 14, 2008 Hey Man, Thanks for posting this up - will be mad helpful when I do mine in a few months... Davros Link to comment Share on other sites More sharing options...
philbey Posted January 14, 2008 Report Share Posted January 14, 2008 (edited) Taz, any more info on the Rising Rate FPR for turbo carbs? I read your post talking about the Carter Black pump etc, but I don't recall you specifying the FPR? I'm not running heaps of boost, so I don't really care about rising rate, but if there is a good one, I might as well use it What, how much and where from? Edited January 14, 2008 by philbey Link to comment Share on other sites More sharing options...
Taz_Rx Posted January 14, 2008 Author Report Share Posted January 14, 2008 Ok, quick re-visit to the ins and outs of carby turbo (or supercharged) fuel system. Draw-through CARBY>TURBO/SC>MOTOR Provided the carby and its components (jets, needle and seat etc) are actually up to the job of flowing enough fuel, the fuel setup required is just the same as any other NA carby car. This is because the carby is not under pressure. You also cannot use an intercooler with this set, as the "air" passing through it is already mixed with fuel...perfect for combustion! :jamie: If you were to have a back fire through the cooler (as there is no throttle body between the engine and cooler) then it would most likely explode taking the other parts from the front of your car with it. Blow-through TURBO>COOLER(OPTIONAL)>CARBY>MOTOR The problem: When you boost a carby in blow through, you also pressurise all of your fuel system - foat bowl, fuel lines, pumps, filter even the tank can feel the effect of the boost. The only way to combat this is to have higher fuel pressure than boost pressure, when ever the car is actually on boost. You always need to keep a buffer of atleast 2-3psi more fuel pressure. This is only ON BOOST, when the car is running in vacuum it only needs the fuel supply of a normal NA carby. There's 2 way i've successfully done this: 1, I used a carter black fuel pump which flows 100gph @ 14-16psi. This is a big pump and would typically be used on a V8 etc, but all you need it for is the pressure. I had 12psi at the engine bay with this pump, and did not use any reg, but that was ONLY because the needle and seat in the weber I was using could hold that pressure at idle. You would not be able you use this setup on say a stock corolla carby as the needle and seat would be forced open and cause it to flood. Keeping a 2-3psi buffer of fuel prsseure, 12psi will allow you to run around 10psi of boost. To use a pump like this with a carby that has a lower needle a seat tolerence see below. 2, Many brands make rising rate fuel pressure regulators for carby cars. These work exactly the same as an EFI RR reg, except they run much lower base fuel pressure. The cheapest and most available seems to be a malpassi (like EFI ones), and can be had on ebay occasionally or bought new for around $100. Heres a cross section of the malpassi... The inlets in the top left and right are paralell and can be used in a couple of different ways. a, used inline befor the carby like a normal NA reg. b, If your carby has a return line, run the line from the pump straight into the carby, and then run the return of the carby into the inlet of the reg. Then block the other inlet/outlet off, or you can use this port for a guage. Both methods will hold the selected base pressure in the fuel lines and carby, then raise it on boost. These regs can be used with both high pressure carby pumps >20psi, or a convention EFI surge tank set up as pictured above, but in both cases a return line must be used. When it comes to running high boost pressure, the surge tank setup is the only way to go as an EFI pump can make more pressure to keep your fuel pressure buffer. As I mentioned above, if high fuel pressure (20+psi) is not needed, but if you would like to run the surge tank setup with an EFI pump, you can run the power source for the EFI pump through a ballist resistor. This will drop the voltage to 6v and halve the output of the pump if it is too high. A rising rate regulator works by using a vacuum/boost line off the manifold. When the boost pressure comes up in the reg, it raises the fuel pressure in relation to boost. you can get them in ratios of 1:1, 1.5:1, 1.7:1, 2:1.....12:1 etc, but most carby ones are 1:1. With a base pressure of 4-5psi (which most carby will hold) and a rising rate index of 1:1 no matter how much boost you run, that 4-5psi will always be your buffer. Think that about covers it. 8/ Link to comment Share on other sites More sharing options...
philbey Posted January 14, 2008 Report Share Posted January 14, 2008 sweet. My mate whose car this setup is currently on didnt bother with a high pressure electric pump and subsequently leaned the thing out til she popped. Taz, you run a boxed carb on your rolla. Rather than box mine up, I have been reading about running a pressure line from the manifold to the fuel bowl. Do you know any advantages with boxing it up rather than a pilot line? Not only that, but I'll probably need to drill and tap a fitting in the fuel bowl lid in order to do this wont I, because the vent isnt particularly easy to plumb a fitting to. (Any pics on where the vent is would be great) Link to comment Share on other sites More sharing options...
Taz_Rx Posted January 15, 2008 Author Report Share Posted January 15, 2008 The idea behind the "pilot line" is to keep even pressure on both sides of the jets in a carby with a SEALED FLOAT BOWL. Some carby have a vent for the float bowl in the top, when using a hat or box with these, boost can easily get into the float bowl and keep even pressures. If your carby does not have this vent, a pilot line may be necessary. Even if you have the correct fuel pressure, because of the air that is also in the float bowl, it will not pressurise properly. So befor the needle and seat, pressure will be right, after the jets the pressure will be right, but in between the 2 there will be a pressure difference causing you issues. By tapping the pilot line into the top of the float bowl, this illiminates that prssure difference and evens out all pressures. Its all about even pressures on both sides, just like the way a watse gate works. To help you understand, here's a little old-skool trick I learn recently for water methanol injection. Water methanol get injected into the plenum/manifold very similarly to N02. I was thinking of using a water washer bottle and pump, as you don't need any more flow than this. Problem - One of those pumps wouldn't make any decent pressure, and would not be able to push the water/meth into the plenum against any boost pressure. Even if you put a small one way valve in this line so boost could not get back into the water/meth bottle the pump simply could push against the boost. The solution, this is sooooooo simple: Make sure your water/meth bottle is sealed and holds as much pressure as boost you're running (this were the washer bottle gets impracticle, and you need to look at stainless steel or alloy). Tap 2 fittings into the top of the bottle. Put a one way valve onto one of these so the bottle can suck in air as the water level goes down (just a breather), the other side of this valve just goes to atmosphere. On the other fitting, use another one way valve, in the same directs (so air can get, but not out), and run this line also into the manifold. See pic below. Now, when ever the manifold/plenum see boost, so does the inside of the water methanol bottle, putting even pressure on both sides of the small pump, which can then actually flow the water /meth into the manifold. The second one way valve on the boost line from the manifold is only there to stop vacuum getting in off boost. If it did, it would open the other breather one way valve as well, and cause a vacuum leak to the manifold. This will also cause the water/meth bottle to hold pressure off boost, and it doen't have to re-pressurise every time. Link to comment Share on other sites More sharing options...
philbey Posted January 15, 2008 Report Share Posted January 15, 2008 Bingo. Has anyone done the drill and tap option - I can't imagine its too hard, but if someone has a pic of a previous attempt that would be handy. I was also thinking that a one way valve in the pilot line (couldnt think of a better name) would be a pertinent idea, otherwise sloshing fuel when off throttle might cause some mixture issues. I was also thinking of water injection, but using a little piston air pump to do produce the pressure differential. What sort of pump are those washer pumps? If they are diaphragm or piston type pumps, you might have trouble if the pressure at the inlet side is to high, because of fluid bleeding past the reeds, or it may struggle to start u[. If its a gear/vane pump though, it should be fine. I have a few pressure pumps lying around as well that I acquired through my travels, shouldn't be too hard to dodgy up. What were you going to use for a spray nozzle? I was thinking some fine stainless tube with an end flattened, and solder into the inlet runners. Link to comment Share on other sites More sharing options...
Trev Posted January 15, 2008 Report Share Posted January 15, 2008 Here's a pic i used as a reference, Might be of use to help out: Link to comment Share on other sites More sharing options...
philbey Posted January 15, 2008 Report Share Posted January 15, 2008 nice sized surge tank - looks suspiciously like a coke tin painted flat black! haha. Link to comment Share on other sites More sharing options...
Taz_Rx Posted January 15, 2008 Author Report Share Posted January 15, 2008 good pic Trev, theres one small problem with that setup though. The return from the surge tank to the main tank should be at the very top swapped with the low pressure pump feed. Then you know your surge tank is full befor it starts returning. 8/ Link to comment Share on other sites More sharing options...
Trev Posted January 15, 2008 Report Share Posted January 15, 2008 good pic Trev, theres one small problem with that setup though. The return from the surge tank to the main tank should be at the very top swapped with the low pressure pump feed. Then you know your surge tank is full befor it starts returning. 8/ Yeah thats what i noticed, With mine i wanna do the tank feed and engine supply down the bottom and returns up the top, I basically got it for the pump setups. Link to comment Share on other sites More sharing options...
tas_ae71 Posted April 12, 2008 Report Share Posted April 12, 2008 cheap, quality surge tanks, aus made $65 http://www.ae86drivingclub.com.au/board/in...mp;#entry516945 Link to comment Share on other sites More sharing options...
Jono Posted April 12, 2008 Report Share Posted April 12, 2008 (edited) that pic of trevs is my first ke20's boot. i swapped it all to my current corolla with the changes it needed. looks neat though and works ok. i also added another filter so it filters from the tank, before the main pump and after the main pump. Edited April 12, 2008 by Jono Link to comment Share on other sites More sharing options...
Trev Posted April 12, 2008 Report Share Posted April 12, 2008 that pic of trevs is my first ke20's boot. i swapped it all to my current corolla with the changes it needed. looks neat though and works ok. i also added another filter so it filters from the tank, before the main pump and after the main pump. I was wondering who's it was, I have had it for a very long time and i can't remember where i got it from. Link to comment Share on other sites More sharing options...
Recommended Posts