RT Posted January 17, 2008 Share Posted January 17, 2008 So I want to run a Holley600 carb to run my engine in before swapping to my throttlebodies.. at the moment I have a Bosh EFi 45psi pump. The throttlebods are internallly regulated to run between 15-20psi. Their official kit somes with a 45psi pump so I should be okay there. But the carb has to run at 7psi.. I have a holley carb external pressure regulator here 0-15psi. Does anyone know if that would be able to dump enough pressure from 45psi to 7psi to run the carb?? I do have a low pressure carb pump here that I can use. But if I could get away with using the EFi pump already installed I can dyno my car with the carb and then swap to the throttlebodies super quick without having to muck around changing fuel pumps. (anyone still reading please reply) Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted January 17, 2008 Share Posted January 17, 2008 suck it and see, i guess. will be a shitload of volume to be dumped via the return.... If it were me I'd run with the low pressure number, that said, checking it doesn't pop the needle valves out with it pumping pressure statically to the carb isn't a hard task Quote Link to comment Share on other sites More sharing options...
mikuni Posted January 17, 2008 Share Posted January 17, 2008 Normally EFI pumps have a less restricted path and just go flat out at 45psi to maintain a constant flow to the fuel rail. I imagine that it probably would work (providing you don't blow the fuel hose by having 45psi getting returned to 7psi) but it would probably burn out the pump pretty quickly. Unless the FPR has a return on it so its limiting the pressure and returning excess pressure straight to the tank but I haven't seen one of them before. Quote Link to comment Share on other sites More sharing options...
Burntrubber Posted January 17, 2008 Share Posted January 17, 2008 I used an efi pump for my carbi turbo setup. The power to the pump was only 7v so it only ran 20psi and my holley regulator could get that right down to 0psi. Quote Link to comment Share on other sites More sharing options...
RT Posted January 17, 2008 Author Share Posted January 17, 2008 the fuel pressure reg has a return line on it for sure. And a gauge. the throttlebod inbuild reg has a return line on it also. Quote Link to comment Share on other sites More sharing options...
mikuni Posted January 17, 2008 Share Posted January 17, 2008 Fuck that would be so sweet aye. I didn't think of what burntrubber said about limiting the voltage to it. Perhaps you could wack a resistor in there aswell. Quote Link to comment Share on other sites More sharing options...
RT Posted January 17, 2008 Author Share Posted January 17, 2008 the way I see if, if the throttlebody kit came from Holley with a 45psi EFi pump with a regulator to drop that down to 15psi.. then I should be able to use my other Holley regulator to drop the 45psi down to 7psi for the carb to run for a few months eh? Then again, it could be safer just to swap pumps at the dyno shop eh. And then it's done. The whole point of this excercise is so I can dyno it on the carb and then the TBi quick and easily.. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted January 18, 2008 Share Posted January 18, 2008 I think you would be better to just borrow a LP pump. Also - 7psi sounds like quite a bit. I don't know Holleys but Webers and the like desire around 3.5 psi Quote Link to comment Share on other sites More sharing options...
sholdowa Posted January 18, 2008 Share Posted January 18, 2008 Can you not just fit both temporarily, and just power up the one you're after? Plenty of rr time then Quote Link to comment Share on other sites More sharing options...
RT Posted January 18, 2008 Author Share Posted January 18, 2008 could.. except for the annoyance of buying and fitting extra fuel lines.. I think shadow is right.. prolly just gonna have to swap pumps. Quote Link to comment Share on other sites More sharing options...
sentra Posted January 19, 2008 Share Posted January 19, 2008 nothing 1 Quote Link to comment Share on other sites More sharing options...
sentra Posted January 19, 2008 Share Posted January 19, 2008 bah i just realised i haddnt thought that through. and i imagine they haddnt eaither. just run the efi pump straight to the carb then bleed off pressure in that line with a normal 2 port lp reg t'd into it with the other port returning to the tank. 1 Quote Link to comment Share on other sites More sharing options...
lowlancer Posted January 20, 2008 Share Posted January 20, 2008 I've read about cunts burning efi pumps out on carb setups from regging them too much. I figure, given the amount of money and time you've sunk into this, you may as well continue to do it right. You've done a mega job thus far Quote Link to comment Share on other sites More sharing options...
Testament Posted January 20, 2008 Share Posted January 20, 2008 it probably depends on the pump a bit. the pump will only really make pressure if it has a restriction to pump against. If the regulator is big enough and you have a good sized return line it should be ok. It's not unheard of, factory lancia volumex (carby supercharged engine) models ran the same bosch pump as the injected models. Quote Link to comment Share on other sites More sharing options...
fishtailfred Posted February 4, 2008 Share Posted February 4, 2008 All you guys need to stop and consider the difference between flow and pressure and the relationship between them. EDIT : except testament there is no such thing as a pump that puts out XX psi. period. there is such a thing as the max pressure the pump can handle, and the pressure that its flow is rated at. usually they have a no load flow too. ie, at 0psi my 044 will move 300lph. at 75psi its down to about 255lph or so. it only falls on its face at some horrendoues pressure like 120psi. hence i chose it for boost. (boost you have boost + base pressure of 40 - 50 psi or more, so i could end up pushing the pump to around the 90psi + mark with 60 base and 30 boost.) consult the fpr manufacturer as to the maximum flow capability of the regulator. that will give you an answer. which bosch pump do you have? hope that helps. fred. Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted February 4, 2008 Share Posted February 4, 2008 I wouldn't use the efi pump unless the reg is a "return style", rather than a "dead head" style. If your reg is just dead heading the flow, it will fuck your pump. If your reg regulates the pressure by bypassing the fuel straight back to the tank (Kinda like what malapasi regs do) then it should be okay. slightly off topic, I run a holley blue on my datsun, with a mallory reg. Because my reg is a dead head (Dead heads the flow) I run the spare fuel out port back into a return line, with a .060 restrictor oriface. This is beacause my pump moves such high volumes of fuel, (By comparison to my engines requirements most of the time) the pumps internal bypass valve will cause the fuel to heat up too much. So it continually circulates. Quote Link to comment Share on other sites More sharing options...
fishtailfred Posted February 5, 2008 Share Posted February 5, 2008 I wouldn't use the efi pump unless the reg is a "return style", rather than a "dead head" style. If your reg is just dead heading the flow, it will fuck your pump. If your reg regulates the pressure by bypassing the fuel straight back to the tank (Kinda like what malapasi regs do) then it should be okay. Absolutely! I wasn't aware that such regs existed. even my dirty old ute had a return line on its factory carby setup. Quote Link to comment Share on other sites More sharing options...
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