Tazio Posted January 20, 2001 Share Posted January 20, 2001 Amongst other things I am migrating to TBs from carbs for my VX ( which I love ), and amongst the myriad of issues that it raises( tapered or direct, long or short trumpets etc etc, one concerns the fuel tank. Is it simply a matter of providing a return path for the fuel or is it more involved?, ( I appreciate it is a closed loop system and will need a high pressure pump and filter, what I really need to know is if anyone knows who manufactures the tank so I can discuss it with them - Thanks L7 FUN Edited by - Tazio on 21 Jan 2001 20:46:13 Link to comment Share on other sites More sharing options...
StewartG Posted January 20, 2001 Share Posted January 20, 2001 Apparently you can have a swirl pot exactly what this does I don't know but I know a man who does and his will probably be the next posting. Link to comment Share on other sites More sharing options...
Jason Plato Posted January 20, 2001 Share Posted January 20, 2001 There is quite a lot of plumbing to br done if you want to fit a swirl pot - a swirl pot removes air from the system and then provides a constsnt level source of feul as you dont want any air in the system going through to the injectors . Also you will need a high pressure feul pump between the pot and the feul rail and a return pump to the tank ( depending on delivery rate ) OR see if you can pick up a second hand Kseries or VX injection feul tank with all the gubbins attached . This would make life much simpler . dave Link to comment Share on other sites More sharing options...
AMMO Posted January 20, 2001 Share Posted January 20, 2001 Dear Tazio (Nuvolari?) I can suggest an alternative method. You could use your current fuel feed line as a return from the fuel regulator. Get a 1/2" pipe (if you want a push on fitting) or JIC -6 or -8 (if you want a screw on fitting)union welded to the tank. This is mounted low in a convenient position and feeds a pre-filter. Fuel pumps are very fussy about debris. This then feeds to a remote fuel pump. Weber and Bosch make nice ones which will run up to 4 bar reliably. This is the cheapest method I can think of. If the pump fails it can be easily repaired/replaced as opposed to having the pump in the tank which is a hassle if anything goes wrong. The system is like a ring: Tank, pre-filter, pump, high pressure filter, fuel rail/injectors, regulator and return to tank. I don't know about swirl pots as I've never used them. Hope this helps. AMMO Link to comment Share on other sites More sharing options...
Tazio Posted January 20, 2001 Author Share Posted January 20, 2001 Thanks for your responses, I appreciate all that's involved with the upgrade re. high pressure pumps and filters etc., just wantd to know if it's prtactical, or finacially viable to mod my existing tank, not by me I hasten to add, or should I simply bite the bullit and create a revenue generating opportunity for Caterham?? And Ammo, yes it is Nuvolari, a true master of the awesome 1938 Audis L7 FUN Link to comment Share on other sites More sharing options...
EFA Posted January 21, 2001 Share Posted January 21, 2001 Tazio I did this about 6 years ago.... With no swirl pot you get massive fuel surge - this could cause pre-ignition on a higlly tuned engine and melt pistons etc..... I tried the swirl pot and return on the std unbaffled tank but it didn't work well, and the external pumps are unreliable and expensive (if you run out opf fuel and they run dry for over abaout 15secs they sieze) I got through 2 pumps before I went for a tank for an injection tank (baffled) with the pump inside the tank. Depending on power, the K series pump is good for about 250bhp - over this and you need to ditch the K- Series pum and replace it with that from a Rover 820 turbo. This struggles a bit to maintain 65psi on my car, but most injection systems are mapped with 50psi in mind. Arnie Webb Organiser- L7C Le Mans Trip To book for this years Le Mans Trip see The Le Mans Trip Website Its nearly full!!! Link to comment Share on other sites More sharing options...
AMMO Posted January 21, 2001 Share Posted January 21, 2001 Tazio. Arnie has obviously much more knowledge than me on the subject. All my experience is on fuel injected motorcycles with Weber. No swirl pots to be seen anywhere. Also not one single pump failure in five years of racing. Never did run the thing dry though. If you decide to go the K series baffled tank route I'd be interested in your old tank if you want to dispose of it. AMMO Link to comment Share on other sites More sharing options...
Tazio Posted January 22, 2001 Author Share Posted January 22, 2001 Thanks guys, Arnie, can I assume you therefore have a K series tank? Ammo, if I have to replace the tank I'll put it in the For Sale forum once I get over the shock of the price of a new, so keep watching... Alan L7 FUN Link to comment Share on other sites More sharing options...
Mike Bees Posted January 22, 2001 Share Posted January 22, 2001 The std. K-series pump (19gm/s) is marginal at 200bhp. The R500 has a 27gm/s pump. I needed to upgrade to the 27gm/s pump and found that it was cheaper to buy it from Caterham than from Rover. Mike Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 22, 2001 Share Posted January 22, 2001 My Grandmother tells a fine story of having dinner with Nuvolari at the gala banquet after one of the between-the-wars Grand Prix at Donington. At the time my Grandfather was assistant clerk of the course. Nuvolari spoke no English and my Grandmother no Italian. They subsisted on gestures, requesting the salt be passed and suchlike. At the end of the dinner, as my Grandmother prepared to leave the menfolk to their cigars, Nuvolari stood up and swept a single rose from the floral centrepiece of the table and presented it to her. She remembers him as a gentleman. Link to comment Share on other sites More sharing options...
EFA Posted January 22, 2001 Share Posted January 22, 2001 Alan, Your assumption is correct. I know of a Vaux which dynoed at 235 using the stock K series pump. I think the injector durations influences how powerful the pump needs to be. Oh I better say flow rate instead of powerful before soembody tells me off. (PC???) Arnie Webb Organiser- L7C Le Mans Trip To book for this years Le Mans Trip see The Le Mans Trip Website Its nearly full!!! Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted January 22, 2001 Share Posted January 22, 2001 I used a second hand K-series tank and the standard in-tank pump. With my 200BHP engine, this showed significant drops in fuel pressure when snap-opening the throttle. (drops by up to 20psi!). When I changed to the high performance pump as Mike describes, I also noticed a potential short where the connections are resined in, on the outside of the pump. The combination of the new pump and fixing the wiring gave me a rock solid 52psi (I have a fuel pressure guage on the dash), regardless of throttle abuse. The mid range misfires (as described in the handling test) vanished. I'd strongly advise using the higher performance pump with a tuned Vx engine. Alex Edited by - Alex Wong on 22 Jan 2001 15:53:37 Link to comment Share on other sites More sharing options...
Mike Bees Posted January 22, 2001 Share Posted January 22, 2001 It's very wise to have significant over capacity in the pump. Running it on the dyno is one thing, running it in the car is another - if you're accelerating hard then the pump is effectively pushing the fuel uphill. The amount of fuel required is a function of the engine power (no really :-) and efficiency. It'll be an amount of fuel per second, and that's how the pumps are rated too. Mike Link to comment Share on other sites More sharing options...
Tazio Posted January 22, 2001 Author Share Posted January 22, 2001 As ever thanks guys, appreciate all your comments, so it looks like a new tank and R500 pumps etc... Alan L7 FUN Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted January 22, 2001 Share Posted January 22, 2001 Alternatively, just to confuse you, you can use the existing tank but I'm not sure how. Try calling Terry Dutton (Leics, Notts, Derby & Staffs AO) who modified his standard tank and used an external pump. This has the advantage of allowing you to leave the filler alone. The injection tank filler has a smaller inlet which mates to a shortened Rover 100 filler pipe and a rover filler cap or one of Caterham's new aero style caps. I wanted to keep my original filler which mean't alot of bodging. The result works, but it takes a while to fill. Terry's no. is in LF and the contacts page of this website. Alex Link to comment Share on other sites More sharing options...
EFA Posted January 22, 2001 Share Posted January 22, 2001 To confuse you even more........ I cut the original filler neck off the carb tank and welded it on the K tank in the place of the K series filler. Arnie Webb Organiser- L7C Le Mans Trip To book for this years Le Mans Trip see The Le Mans Trip Website Its nearly full!!! Link to comment Share on other sites More sharing options...
Tazio Posted January 22, 2001 Author Share Posted January 22, 2001 I am going to keep the rear clear of holes and have the fuel filler under the boot cover.....I just like a neat rear end, well I am a leg man.. Alan L7 FUN Link to comment Share on other sites More sharing options...
Ian Macquarie Posted January 23, 2001 Share Posted January 23, 2001 I've also been looking at this question. As a guide a new tank, pump, and all the extras from Caterham will cost you over £500 +Vat. Consequently I've been looking at the swirl pot route. I am talking to Raceline and I think parts from them (+ others) to achieve the same will be pretty much half the price. Link to comment Share on other sites More sharing options...
Tazio Posted January 23, 2001 Author Share Posted January 23, 2001 Ian, Thanks for that, let us know on what you decide. Alan L7 FUN Link to comment Share on other sites More sharing options...
EFA Posted January 23, 2001 Share Posted January 23, 2001 All I'll say is my first effort was the cheap way, and I wish I'd gone the K tank from day 1. Alan, first time I failed to return from France was due to an external pump failure on a r/b on the Mulsanne. Just the air in the pump as I did a single 180 degree turn on a bigish roundabout (gues sthis was a problem only in France as I was going round it the other way..)was enough to cause a pump seizure!!! Even with a swirl pot the pump can still run dry! Arnie Webb Organiser- L7C Le Mans Trip To book for this years Le Mans Trip see The Le Mans Trip Website Its nearly full!!! Link to comment Share on other sites More sharing options...
Chelspeed Posted January 24, 2001 Share Posted January 24, 2001 Arnie - what did you use to fill the swirl pot? Was it pumped or just gravity fed? I have a std 1993 crossflow tank modified to add a return from the swirl pot overflow. I use a facet red top (15 years old is that a record?) to fill the swirl pot and then feed the HP pump (external of course) suction from the swirl pot. I have regularly returned from a sprint run with the main tank absolutely empty (the facet pump screaming away with no suction) and have never got near to emptying the swirl pot and starving the HP pump. Did you have the fuel injection return going back into the swirl pot or back to the main tank? The latter will mean the swirl pot empties much quicker of course. In my view the standard tank, LP pump, swirl pot, HP pump route is the way to go. Much cheaper than a new tank. Link to comment Share on other sites More sharing options...
EFA Posted January 24, 2001 Share Posted January 24, 2001 Graham I had a gravity feed to the swirl pot, swirl pot cap was about .5 litre, then into the hp pump which returned to the main tank. Sure the two pump setup may help, but is rather complex, and many points of failure......(something I try really hard to avoid on my car these days...) Arnie Webb Organiser- L7C Le Mans Trip To book for this years Le Mans Trip see The Le Mans Trip Website It really is very very very very full now!!! Link to comment Share on other sites More sharing options...
AMMO Posted January 24, 2001 Share Posted January 24, 2001 Arnie, just out of curiosity what brand was your external pump? Only fifteen seconds to go belly up, I want to make sure I don't buy one. The exteral pumps I am familiar with are also used for in-tank applications (in Ducatis for example). The problem is not the pump, it is making sure it always fed with fuel. Also having realised that I really know nothing about the subject I have made enquiries. I found out that the latest VW's have a box the size of a biscuit tin under the rear seat where the high pressure pump resides. This is fed by a low pressure pump. as I will be going over to fuel injection at some point all this is very interesting. I have a friend who used to build Nissan touring car engines. His bike has a strange appendage attached to the feed side of the pump. When asked he told me "swirl pot". At the time I thought waste of space. Now I'm not so sure. I'll 'phone him today to ask. If the external pump system can be made to work reliably without the addition of an extra pump (extra weight, one more bit to go wrong)that would be good. I'll let you know what I find out. AMMO Link to comment Share on other sites More sharing options...
EFA Posted January 24, 2001 Share Posted January 24, 2001 It was a Facet! Arnie Webb Organiser- L7C Le Mans Trip To book for this years Le Mans Trip see The Le Mans Trip Website It really is very very very very full now!!! Link to comment Share on other sites More sharing options...
Ian Macquarie Posted January 24, 2001 Share Posted January 24, 2001 With a 0.5l swirl pot and a 125 litre /hour pump it would only take about 15 seconds to empty the pot if the return went to the main tank - regardless of the amount of fuel being used by the engine. I was looking at using a 1 liter pot (filled by a pump) with a 100 litre/hour HP pump returning to the pot. If the LP pump lost suction due to surge in the main tank then I would have over a minutes running time on full power from the pot contents, which I thought would be more than enough for my driving habits! However the comment about short HP pump life when pumping dry makes me worried about what happens if you just simply run out of fuel. I don't make a habit of it, but it has happened. All I had to do was walk to the petrol station. Are you suggesting that with an external pumped injection system running out of fuel would result in pump failure needing a repair? What are other peoples experiences of running out of fuel with a HP pump system? Tazio - with regard to my comments about the Caterham price of converting to an injection tank - £80 of that is for a new filler neck and cap - I guess you won't need that. Another £65 is for an Ali boot floor to fit over the top mounted connections on the tank. If your car is newer than mine you may already have one. Raceline did say that the Caterham set up is very good and that they normally recommend customers to go for it. - I just balked at the cost compared with a two pump and swirl/surge pot solution. Mind you I've been waiting since Monday for their fax giving me details of what they can supply and prices so perhaps they really don't want to sell me the surge pot system! Ian Link to comment Share on other sites More sharing options...
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