Schnippel Posted July 25, 2022 Report Share Posted July 25, 2022 Quote Link to post Share on other sites
Schnippel Posted July 25, 2022 Report Share Posted July 25, 2022 Quote Link to post Share on other sites
Jonny TR6 Posted July 25, 2022 Author Report Share Posted July 25, 2022 Thanks Schnippel - that’s a nice low solution. Quote Link to post Share on other sites
Jonny TR6 Posted July 26, 2022 Author Report Share Posted July 26, 2022 Decided to go with the pump and filter mounted outside and the option of a post pump filter in the boot. Mocked everything last night and ordered some fuel hose. Luckily I have a Pirtek near the office, so popped along with my existing pump to t piece hose and some Cohline R9. Rather than split the tails off the old hose and swage the new ferrules in they just went to their huge stock of unions and dug out brand new fittings. 5 mins later I had a properly crimped hose with new fittings. Once I get my bits all in place and finalise hose lengths, I’ll take everything else along to them. One think I’ve noticed and a question for the experts in fluid mechanics, is that they’ve used slightly smaller id fittings than original. Will this affect anything ? The Cohline pipe id is 8mm and it looks to have reduced down to approx 4mm on the inlet and outlet connections. It is on the high pressure side of things though. Quote Link to post Share on other sites
Waldi Posted July 26, 2022 Report Share Posted July 26, 2022 I’m not a process engineer but think it is not ideal, and will result in some extra pressure drop; but since this on the outlet side it may not matter too much. If you can drill them out a bit to what is was original that would be better.If not, just leave as is and see if you can get the pressure set correctly. Waldi Quote Link to post Share on other sites
john.r.davies Posted July 26, 2022 Report Share Posted July 26, 2022 ,Jonny, forgive me if you know this already. Flow through a tube is governed by Possiuelle's Law, whereby the resistance is inversely proportional to the Fourth Power of the radius. So halve the radius as your new connections have done and resistance rises SIXTEEN times! (2x2x2x2) But a connector approximates to an orifice, where flow varies as the Square of the radius. So only (!) Four times! So, as Waldi says, see what pressure it has, and if you can adjust the PRV to compensate. Jhn Quote Link to post Share on other sites
Jonny TR6 Posted July 26, 2022 Author Report Share Posted July 26, 2022 (edited) Thanks both - got to go back anyway with some more fittings/hose so will discuss Possiuelle’s law with them. Bernoulli frightened me off back in the day, which is why I switched from civil engineering to finance ! Edited July 26, 2022 by Jonny TR6 Quote Link to post Share on other sites
Jonny TR6 Posted July 26, 2022 Author Report Share Posted July 26, 2022 As I can get pretty much any fittings attached to any hose, is it worth me upping the hose id to say 12mm - which would mean the fittings id would be approx 8mm and match the hard lines to the MU ? Quote Link to post Share on other sites
john.r.davies Posted July 26, 2022 Report Share Posted July 26, 2022 Jonny, Do you have a pressure gauge? Even one you can plug in for testing? I made one from a spare oil pressure gauge, on a length of Aeroquip hose, and T-connector. But I had to include an orifice to damp out the pulsation that the pump produced, which threatened to whip the needle off the gauge! A disc of copper, made from a spare length of tubing cut open, with a TINY hole in the middle - a 1mm drill, achieved a static needle, when inserted into the gauge connector. Then, I'd connect up what you have and see if the PRV can be adjusted to deliver the necessary 100-110psi. Do you have the OE PRV? That is fiddly to adjust and cannot be done 'on the fly', but modern PRVs that are adjustable in use are available. Just don't buy one from China that ahs its' own pressure gauge built in! I did, and the Bourdon tube on the gauge BURST! Flooding the boot with fuel! If the PRV can't cope, then revise your hoses as you suggest. I have 10mm copper pipe for most of the length between the boot and the engine, so 12mm will be fine. John Quote Link to post Share on other sites
Jonny TR6 Posted July 26, 2022 Author Report Share Posted July 26, 2022 Thanks John - got an original PRV so think I’m going to bite the bullet and get a diaphragm one. I can also get some braided stainless 100% ethanol proof 12mm id fuel hose, so will probably go with that throughout, low pressure and high pressure. Only need 1m or do and then I’m future fuel proof at the back end of the car. Will also need to get a fuel pressure gauge made up. Thanks for the input - really helping me get this sorted. Cheers Jonny Quote Link to post Share on other sites
tim hunt Posted July 26, 2022 Report Share Posted July 26, 2022 5 hours ago, john.r.davies said: ,Jonny, forgive me if you know this already. Flow through a tube is governed by Possiuelle's Law, whereby the resistance is inversely proportional to the Fourth Power of the radius. So halve the radius as your new connections have done and resistance rises SIXTEEN times! (2x2x2x2) But a connector approximates to an orifice, where flow varies as the Square of the radius. So only (!) Four times! So, as Waldi says, see what pressure it has, and if you can adjust the PRV to compensate. Jhn POISSEUILLE'S LAW please Quote Link to post Share on other sites
Jonny TR6 Posted July 26, 2022 Author Report Share Posted July 26, 2022 2 hours ago, tim hunt said: POISSEUILLE'S LAW please He’ll be cavitating in his grave… Quote Link to post Share on other sites
john.r.davies Posted July 26, 2022 Report Share Posted July 26, 2022 mon erreur! mon orthographe est merdique Quote Link to post Share on other sites
Jonny TR6 Posted July 29, 2022 Author Report Share Posted July 29, 2022 My Prestige PRV has arrived. Are these usually fitted with a bracket or do you rely on the connection to the brass T for stability ? Popped Carl a message asking the question, but thought I’d ask here whilst I await a reply. On trial fitting and with the brass T in its usual place, the mounting plate on the PRV fouls the wheelarch, which would necessitate relocating the brass T and associated return from the MU. Quote Link to post Share on other sites
Jonny TR6 Posted July 30, 2022 Author Report Share Posted July 30, 2022 (edited) Installed without a bracket - as was my original PRV and all ok. Just the rest of the gubbins to plumb in… Edited July 30, 2022 by Jonny TR6 Quote Link to post Share on other sites
Mk2 Chopper Posted July 31, 2022 Report Share Posted July 31, 2022 Looking good, nothing better than a clean installation done right. Gareth Quote Link to post Share on other sites
Jonny TR6 Posted July 31, 2022 Author Report Share Posted July 31, 2022 Taken me a while to understand everything Chopper ! Another idiot question - my final bit of assembly is the fuel pump to brass T. If I have 8mm id pipe from the tank to the pre filter, should I stick with 8mm id from pump to brass T or can I use 10mm id ? To my mind, you can’t pump a bigger volume of fuel than has gone in, so going to 10mm would be pointless ? Always the option to change the tank outlet to 10mm of course, but if 8mm is sufficient I’ll stick with it. The banjo hose tails of course are probably 6mm id… No wonder it’s complicated ! Quote Link to post Share on other sites
Mk2 Chopper Posted July 31, 2022 Report Share Posted July 31, 2022 If you intend to increase the tank outlet in the future then maybe go for 10mm, but I doubt it'll make any difference at all leaving it all at the 8mm. Yes it can be a bit of 'fun' figuring it all out, but what better way to get to know your car and enjoying the mechanical side of it as well as driving it. Gareth Quote Link to post Share on other sites
Jonny TR6 Posted August 2, 2022 Author Report Share Posted August 2, 2022 Progress being made on the outside. Mocked up the location of the pre filter and pump and made a cardboard template so I can get a mounting bracket fabricated. I want the pump to sit on rubber isolation feet - similar to the brass T ones, to reduce vibration through the body. Quote Link to post Share on other sites
john.r.davies Posted August 2, 2022 Report Share Posted August 2, 2022 Jonny, You may want to change that filter some time. A turn of hose between it and the pump makes for easier reinstallation, than such a short length. My modern PRV, like yours from Prestige, I have mounted on its own bracket. It has some mass and out on the end of the OE valve body, will expert a moment on the connections if not supported. No pic, I'm out and on my mobile. Glad to post if you wish. John Quote Link to post Share on other sites
Jonny TR6 Posted August 2, 2022 Author Report Share Posted August 2, 2022 Thanks John - it’s all change again ! Just been out to my local Pirtek and scavenged a long length of braided PTFE hose in 10mm id. They’ve also got loads of tails (no banjos) so going to measure up what the banjo diameters and order up some larger 10mm id banjo bolts, so will eventually run 10mm all the way to the brass T. Appreciate the comments on the PRV bracket. Will get one made up when I pick up the fuel pump/filter bracket. Re changing the filter, it’s a bvgger to get onto the filter tail, so designing the system so that the fuel pump and filter come out together when doing a filter change. Will probably change the double ear o clamp for a fuel hose clip though at the filter side, as it’s low pressure. And rest…… Quote Link to post Share on other sites
Mike C Posted August 2, 2022 Report Share Posted August 2, 2022 To help with filter changes I installed a full bore SS ball valve in the suction line. Easier than pipe clamps and might be useful in the event of a catastrophic leak in the system below the tank fuel level. Quote Link to post Share on other sites
Jonny TR6 Posted August 2, 2022 Author Report Share Posted August 2, 2022 Thanks Mike - on my shopping list ! Quote Link to post Share on other sites
Jonny TR6 Posted August 3, 2022 Author Report Share Posted August 3, 2022 Another hurdle in my never ending mission to sort out my fuel system ! My aluminium tank outlet has a 12.5mm dia banjo bolt with a 1.25 pitch on the thread. The banjo itself is 13mm to an 8mm hose tail. What I need to convert everything to 10mm is a 13mm banjo to a 10mm hose tail. Otherwise I'm stuck with 8mm to the filter and 10mm from there on, which is somewhat defeating the object. I've searched around, but no joy. Quote Link to post Share on other sites
jpmf Posted August 3, 2022 Report Share Posted August 3, 2022 (edited) Fitted one of these on outside, hopefully cure the petrol fumes in boot Edited August 3, 2022 by jpmf Pictures Quote Link to post Share on other sites
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