Ian C Posted December 18, 2003 Share Posted December 18, 2003 Single turbo, say 600bhp's worth, would you need one or two Walbro fuel pumps to feed it? Nathan and Chris Wilson reckon one would do, Terry, Mohd, and Klaus Svoboda reckon on two. I wouldn't want to fit a second one for the fun of it if I were going to get a single turbo, as it looks like a nasty cutting/welding/routing pipework job and of course it's extra £££s. But I would fit a second if one on it's own wasn't man enough or was at it's limits. Also, could you just plumb in two pumps to the same fuel line coming out of the tank, as that would be much easier to implement? -Ian Link to comment Share on other sites More sharing options...
randy Posted December 18, 2003 Share Posted December 18, 2003 Definately think a second pump would give some degree of safety to your fueling just in case one pump fails for some reason also the stock fuel line would cause a restriction... Also its better to have a second line, than just increasing the fuel pressure with one line ... You also wont over work a single pump! Link to comment Share on other sites More sharing options...
Ian C Posted December 18, 2003 Author Share Posted December 18, 2003 Well, the last thing on my mind is redundancy, because you actually add a degree of danger with two pumps. If one fails (and there is now double the chance of that) and you need both to provide adequate fuelling, suddenly you'll run lean as the remaining pump struggles. Having two pumps is something I'm actually classifying as a risk, rather than a good thing I understand your reasoning behind the pressure on the stock fuel line, but I would only want two pumps if I needed it, so really I'm looking for responses from people who have actually tried the single pump route and found it inadequate or perfectly OK. Unfortunately that sort of rules out people who went straight to the double pump method because they were told they needed it -Ian Link to comment Share on other sites More sharing options...
randy Posted December 18, 2003 Share Posted December 18, 2003 OK mate! Link to comment Share on other sites More sharing options...
Adam W Posted December 18, 2003 Share Posted December 18, 2003 Ian, I worked out the volume flow requirements of 550bhp (my target at the time) and IIRC it was quite near the top end of what the Walbro 341 can deliver. A lot of it depends on what your rail pressure will be at the time you need max fuel delivery. The pump will be able to flow lots more GPH at low rail pressure than at high rail pressure. So if you set your base FP to 50psi and then run 25psi of boost there will be 75psi backpressure that the pump is working against, and the GPH will drop right off. Link to comment Share on other sites More sharing options...
Guest Terry S Posted December 18, 2003 Share Posted December 18, 2003 Big C, you know my thoughts. Whilst I think the Walbro could probably get there, do you really want it operating at it's upper limits. Also whats so hard to add another line & filter to your new rail? If you really are worried and only want one pump, mount one of those horribly noisey externals under the car. Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 18, 2003 Share Posted December 18, 2003 Bosch Motorsport 044 pump, externally mounted. If properly insulated they should be all but silent. At least if it goes on the blink you aren't having to delve inside the tank. In fact, you don't have to delve inside the tank at all if you do it really properly and use a swirl pot fed by the stock pump. At low pressure it will flow a huge amount... Search on fuel swirl pots and you will find loads of schematics. Link to comment Share on other sites More sharing options...
Guest Terry S Posted December 19, 2003 Share Posted December 19, 2003 Chris, I have to admit I have never heard the Bosch pump you are on about, but you know what I mean about most external pumps. How much are they Chris? That may be your solution Ian if you are dtermind not to install another pump. Link to comment Share on other sites More sharing options...
Wez Posted December 19, 2003 Share Posted December 19, 2003 I managed to find one for about $500 so not sure how much over here, apparently biggest pump bosch do and works with alcohol as well. Link to comment Share on other sites More sharing options...
Wez Posted December 19, 2003 Share Posted December 19, 2003 Chris, Is this the pump you are talking about :- http://www.fuelsystem.co.uk/new_page_10.htm If so they are about £180 +vat and delivery. Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 19, 2003 Share Posted December 19, 2003 That's the one. I may be able to supply at a better price, i bought 2 a while ago, can't find the invoice at the moment though, books are at the accountants. Do you want me to check? Link to comment Share on other sites More sharing options...
Guest Terry S Posted December 19, 2003 Share Posted December 19, 2003 Unless I am being totally daft it flows similar to a UK Intank pump so I fail to see and advantage. Like I say I may have misread the chart. Off for our Chrimbo lunch so will check back later. Link to comment Share on other sites More sharing options...
Ian C Posted December 19, 2003 Author Share Posted December 19, 2003 Thanks for all this info guys, good stuff What I'm looking for is a fuel delivery solution that can use the stock fuel lines with minimal hacking about. One big pump in the tank would be ideal, one big pump outside the tank would require some of that metalworking nonsense that scares me so much, two pumps in the tank that pipe into the same feed line still within the tank would be ok, two pumps with seperate fuel lines like Mohd has got can bog off as it's way too much effort So really I'm looking for an in-tank solution, be it one big pump or two feeding into the same bit of hose. If neither of those are viable, only then would I be looking at an external pump with whatever a swirl pot is -Ian Link to comment Share on other sites More sharing options...
Ian C Posted December 28, 2003 Author Share Posted December 28, 2003 Punted back to the top after the christmas lull Dude - you're planning a single setup, what's your approach for the fuel pump side of things? -Ian Link to comment Share on other sites More sharing options...
Wez Posted December 28, 2003 Share Posted December 28, 2003 I am going to see how it goes with a single walbro and then add another if I need too. Link to comment Share on other sites More sharing options...
dude Posted December 28, 2003 Share Posted December 28, 2003 Originally posted by Ian C Punted back to the top after the christmas lull Dude - you're planning a single setup, what's your approach for the fuel pump side of things? -Ian Ian i worship the great God Terry the Large and he has decreed that i need to sacrifice 2 walboro pumps to him !!!!! Once ive fitted the second and had the fuel line made i can get another done for you it will not be that dear and quite easy to fit running parralel!! to the stock line but it will be in braided line not hard pipe using a bulkhead fitting at the tank and a stock second filter , only difference is wether you want the line to the front or rear of the fuel rail . Dude Link to comment Share on other sites More sharing options...
Ian C Posted December 28, 2003 Author Share Posted December 28, 2003 Well, the approach Wez is taking is one I've been considering but at the end of the day if I do need another pump, which seems likely, a) I had better start planning for it now and b) I may as well install it too, seeing as a Walbro 341 is $125 from the states and it would go with everything else, thus saving on the shipping. Just realised I'm typing like I'm actually going to do the upgrade at last, there goes my last sliver of pretense I'm only thinking about it So, what's the bad thing about just 'Y'-ing the two pumps into the same feed line that goes through the pump cage? Minimal extra hosing, no cutting metal, only problem I can see is if using the stock fuel line and only the stock fuel line causes a major bottleneck... -Ian Link to comment Share on other sites More sharing options...
Guest Terry S Posted December 28, 2003 Share Posted December 28, 2003 Big C/Dude. I have been thinking this over, and I can see Ian's concerns. I was talking to Mark Shead who is building a 600bhp cossie for a customer. His approach is to build two rails, each being feed by one pump. The theory being is one pump went down the car would lose 2 cylinders ( or in our case 3) and would run so badly that you stop before causing any damage. The return/FPR would needa bit of thought. The other way is a huge external pump, -10 line which then Y's to 2 x -6. I have yet to hear a quite external pump which is capable of supporting the kind of BHP we are talking about. The twin in tank route is tried and tested, but there is always the danger of one pump going down and causing the car to run lean. What we are really looking for is an intank pump which flows 3~350 lph. Any thoughts? Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 28, 2003 Share Posted December 28, 2003 I can probably find in tank F1 or F3000 pumps that will flow that much, but the buggering about to fit one in the Supra tank would be similar to an external pump. I say go external with a swirl pot, feed the pot with the stock pump. Use one of these Bosh pumps and either use Aeroquip type braided lines to the rail 9the stock return is fine) or hard pipe it and brave the metal bending *Skyline R33 stock GTR pump is 190 litres per hour and supports circa 420 bhp at standard pressure *Bosch 910 pump is 200 litres per hour at 73.5 PSI # 0 580 254 910 *Bosch 975 pump is 228 litres per hour at 73.5 PSI # 0 580 254 975 *Bosch 984 pump is 228 litres per hour at 73.5 PSI # 0 580 254 984 *Bosch 044 pump is 330 litres per hour at 73.5 PSI # 0 580 254 044 *Bosch 040 pump is 235 litres per hour at 73.5 PSI # 0 580 254 040 The 044 pump is good for around a 700 BHP six cylinder turbo engine, it even meets the needs of serious race rotary engines which absolutely gulp fuel. You can run a pair in parallel if you want to go mad, but it shouldn't need anything like that sort of fuel system. I can get beautiful uprated 044 pumps with removable body ends for cleaning, about 75 quid more than a stock one. A bit more flow and a billet case.... Link to comment Share on other sites More sharing options...
Ian C Posted December 28, 2003 Author Share Posted December 28, 2003 I hate to labour the point but if one Walbro is borderline for a moderate single turbo, wouldn't two of them Y'd to the stock fuel line, tank-side, be perfectly OK? Barring the pump failure issue. External tanks and swirl pots are probably off the cards, Chris. I know you like doing things 'properly' but I'd rather do twin in-tanks and two fuel lines than go bonkers with a racecar install Wait until you find out I've chosen the E-Manage to control the fuelling and timing, you'll excommunicate me But believe me, it was after a lot of research - many insomniacs were cured on this BBS -Ian Link to comment Share on other sites More sharing options...
Guest Terry S Posted December 28, 2003 Share Posted December 28, 2003 Chris it has been a long time since I had anything to do with external pumps. Do they still sound like tommy guns, even when used with AV mounts? Ian, the downside of using the stock fuel line is that you are relying on 1 x -6 line to feeding the stock rail. This may be OK but I am not sure about the distribution within the fuel rail. Most after market rails feed - 6 either end. Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 28, 2003 Share Posted December 28, 2003 Well, just feed an 044 with a stock in tank pump. As it is only feeding at low pressure it will flow more than enough for the 044 to deliver its full pressure and flow if needed. The stock fuel line is small, so you would really have to change the pipe all the way from an in tank pump pairing to the rail, and the hard part for you might be the bit where the pipe leaves the tank.I have done a few MR2 conversions using the stock in tank pump as a simple lift pump to a bigger external job. Link to comment Share on other sites More sharing options...
Ian C Posted December 28, 2003 Author Share Posted December 28, 2003 And if I split the line to go either end, it would halve the pressure, wouldn't it? Either dropping the pressure too low or making the pumps work even harder - probably about 120psi in the single bit of toob Is that a Bad Thing that I shouldn't do, though? This is beyond what I can work out in my head, I need real-world experience -Ian Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 28, 2003 Share Posted December 28, 2003 Originally posted by Terry S Chris it has been a long time since I had anything to do with external pumps. Do they still sound like tommy guns, even when used with AV mounts? Ian, the downside of using the stock fuel line is that you are relying on 1 x -6 line to feeding the stock rail. This may be OK but I am not sure about the distribution within the fuel rail. Most after market rails feed - 6 either end. An 044 is used in the 911 turbo, and it's silent. Just mount it properly and it will be fine. The stock RAIL will be fine, flow wise, but it would be much better to replace all the feed to the rail with something like -10 pipe. I'd do it annealed ali pipe, it's easy to work, but you could use Kunifer or other soft copper alloy too. -10 Aeroquip and fittings do not come cheap though, I think the fuel piping and fittings for my RX came to about 400 notes, that's just pipe and fittings, no pump, swirl pot or anything else. I can put you in touch with people who may have used fittings, which are fine, they are, after all, designed to be RE usable Link to comment Share on other sites More sharing options...
Ian C Posted December 28, 2003 Author Share Posted December 28, 2003 So, it looks like the least-messy answer, in my mind, is twin in-tank pumps, twin fuel lines (one stock, one Aeroquip braided hose with some good securing to the chassis and whatever gubbinsy connectors it needs at each end), one fuel line to each end of the rail, and the minimum amount of metalwork - drilling a hole in the fuel pump cage and doing whatever it is you do to get a removable connection coming out of it without pissing fuel everywhere. Sound like a plan? If I have to bugger about with fuel lines, I'm doing it this way. It just seems neater to me than an external pump, sorry Chris. All the info is as ever gratefully received though Does this mean I get to fit those funky anodised blue bits of plumbing...? -Ian Link to comment Share on other sites More sharing options...
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