randy Posted July 19, 2002 Share Posted July 19, 2002 I am getting this feeling my jap spec fuel pump is not able to handle the extra boost and could be making my car run lean. Does one need to upgrade their jap spec fuel pump to run boost say 16/18 psi? I hear the jap spec pump is smaller and does not flow as much fuel as the UK spec. Quote Link to comment Share on other sites More sharing options...
Alex Posted July 19, 2002 Share Posted July 19, 2002 The fuel load is controlled by the ECU and injectors - if you increase line pressure then you could squeeze more through but if you do that you'll knacker the injectors. Adding a UK spec pump would be best done when doing a full upgrade to a UK spec fuel system. Quote Link to comment Share on other sites More sharing options...
randy Posted July 19, 2002 Author Share Posted July 19, 2002 Alex, Could the performance of my jap spec pump be inefficent especially running boost? Are they any other problems apart from excess pressure on the injectors from upgrading the fuel pump? Will the TDI pump be too strong? Also could I just buy a bosch fuel pump with say 200litres/hr capicity and install? Anyproblems doing this? Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted July 19, 2002 Share Posted July 19, 2002 Going slightly off, but at what stage should one upgrage to 550's and UK pump? What bits are needed? Quote Link to comment Share on other sites More sharing options...
Diane Abol Posted July 19, 2002 Share Posted July 19, 2002 Standard pump and injectors should be more than up to the job of supplying enough fuel for 1.1-1.2. Increasing to a UK pump will richen mixture if needed (even using standard injectors) ; this is common practice among the evo boys. Adjustable fuel pressure reg will also work. Id say, you'd only need to consider larger injectors if running high boost on non-standard turbo's. I have fitted HKS 680cc injectos to mine, with fuel pressure reg (3.05bar) and UK pump - this is enough to fuel 600bhp 8=) Quote Link to comment Share on other sites More sharing options...
randy Posted July 19, 2002 Author Share Posted July 19, 2002 Need info on the jap spec fuel pump! If upgraded to a bigger pump bosch/TDI or a UK spec what are the pros and cons of upgrading? Will it help by richen up the fuel supply? or will the fuel pressure regulator stop any excess fuel being supplied to the engine? Quote Link to comment Share on other sites More sharing options...
Need4Speed Posted July 19, 2002 Share Posted July 19, 2002 Is the question of fuel pumps one of fuel pressure? If so what fuel pressure should I be looking at to handle 550bhp, and what injectors shoul I fit? I don't have this at present but it is my Holy Grail. Quote Link to comment Share on other sites More sharing options...
GavinL Posted July 19, 2002 Share Posted July 19, 2002 Originally posted by John Packham Is the question of fuel pumps one of fuel pressure? If so what fuel pressure should I be looking at to handle 550bhp, and what injectors shoul I fit? I don't have this at present but it is my Holy Grail. I think that's pretty much covered by the post two up from yours Quote Link to comment Share on other sites More sharing options...
Need4Speed Posted July 19, 2002 Share Posted July 19, 2002 The flow rate of a pump doesn't tell what pressure it delivers. I thought fuel pressure was the issue here. Maybe I'm wrong... point me in the right direction. Quote Link to comment Share on other sites More sharing options...
GavinL Posted July 19, 2002 Share Posted July 19, 2002 Originally posted by randy I am getting this feeling my jap spec fuel pump is not able to handle the extra boost and could be making my car run lean. Does one need to upgrade their jap spec fuel pump to run boost say 16/18 psi? I hear the jap spec pump is smaller and does not flow as much fuel as the UK spec. I would suggest that you consider investing in a large front mounted intercooler and/or water injection. The under bonnet and especially air temps (even at night) will be higher than we experience for most of the year in the UK, both of these are recommended for the british climate. Quote Link to comment Share on other sites More sharing options...
Adam W Posted July 19, 2002 Share Posted July 19, 2002 Fuel pumps are rated in Gallons per hour at a given fuel pressure. They will pump less GPH as you increase the fuel pressure in the system that they have to "pump against". The actual fuel pressure is not determined by the pump at all, but by the fuel pressure regulator. When trying to get more fuel into your engine, you have two choices - 1: increase the line pressure to squirt more fuel through small injectors or 2: Get bigger injectors 1 is not recommended - the injectors have a set operating range and if you exceed this pressure (about 50psi base pressure at a guess) there is a danger they will permanently lock open or closed, plus as the pressure goes up their spray pattern is affected, along with atomisation of the fuel mixture, hence combustion efficiency etc. 2 is the way to go! The "550" or "680" for injectors means the cubic centimetres per minute of fuel they will flow at max safe "duty cycle" (the proportion of the time that the injector is open) and a set fuel pressure (you may need an adjustable Fuel Pressure Regulator to achieve this pressure). At the website for RC engineering there are calcs you can do to work out what size injectors you need for a set horsepower. Say you want 450bhp, you might need six 550cc/min injectors running at 45psi base fuel pressure. These injectors, when fully open, will be flowing ~50gallons per hour (work this out using density of petrol, volumes etc). Your max fuel pressure is determined by (base fuel pressure) + (max boost pressure). As boost goes up, your fuel pressure regulator will increase the fuel pressure by the same amount, so that the pressure differential across the injector (ie between the fuel rail and the manifold) stays constant. (Steer clear of rising rate FPR's, these increase fuel pressure by, say, 1.5 or 2 psi for each 1psi boost increase. From what I've heard, they're a nasty bodge. ) So, if your base fuel pressure is 45 psi and your max boost is 18 psi, your max fuel pressure will be 63psi. This means that your pump will need to be capable of flowing 50gph@63psi. Simple, innit? At this point you may also wish to consider buying a fuel computer, such as the Apexi SAFC, to allow you to fine tune your fuel mixture. Following any fuelling mods, you should get your fuel mapping checked on a dyno by someone with a WIDEBAND O2 meter, this will tell you if you are in danger of running lean or not. I have just upgraded the fuel system on my Mk3, hence I had to do all the research above, and I discovered that replacing one item without upgrading the whole lot will have minimal benefits. On nearly all cars, the whole system will be pretty well matched - the pumps capacity will match the peak flow of the stock injectors at a pressure determined by the stock fuel pressure regulator. If you increase fuel pressure to try and force more fuel in, you may knacker your injectors. Also you will quickly reach a point where the stock fuel pump can't supply that much fuel at that much pressure. You will also exceed the stock pumps flow limitations if you try and run really big injectors. It's one of those jobs you just have to do properly, or not at all, if you don't want a melted engine at some point. Quote Link to comment Share on other sites More sharing options...
Need4Speed Posted July 19, 2002 Share Posted July 19, 2002 Adam, thanks for that. I had assumed it was a case of matching fuel delivery to boost pressure to ECU etc. but was reading alot of stuff about UK fuel pumps as if it was a solution to all thing fuel. I have my engine performance worked out now. All I need to do is sort the barkes. Who in their right mind in Japan thought those J-spec brakes would stop a Corolla? Let's go to work! Quote Link to comment Share on other sites More sharing options...
Need4Speed Posted July 19, 2002 Share Posted July 19, 2002 Barkes?? I must preview in future. Oh well, back to the fridge! Quote Link to comment Share on other sites More sharing options...
randy Posted July 20, 2002 Author Share Posted July 20, 2002 Thanks for that write up Adam! Senior Gavin, I agree I should get myself a FMIC soon planning the HKS-type-S. I am in the process of buying a new set of brakes and new wheels/tires which is kinda expensive landed cost with duty. UK-spec brakes with Apex rotors and also the BLITZ Technospeed Z1 19"/ with Bridgestone P's. Later! Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted July 20, 2002 Share Posted July 20, 2002 Originally posted by Diane Abol Id say, you'd only need to consider larger injectors if running high boost on non-standard turbo's. Like stage III hybrids then (which I've not got yet, but I like to plan ahead) Quote Link to comment Share on other sites More sharing options...
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