lpg feed pipe size on 500 bhp engine.

[robertXX]

hi chaps , back again with a new project , and i have a quick question .

re a projected 500 bhp twin jag engined car..

if i have 2 r90 reducers ,with what appears to be 6mm gas inlets ,and the fuel tanks i have available have what appear to be 5 to 6mm gas outlet diameters , do i

a) use 8mm pipe ,and 8mm to 6mm reducing adaptors at all connections.

or

b) remove all the 6mm fittings ,and replace with 8mm ones , including the filters fittings..


if the 6mm is restrictive , how is the r90 fitted with a 6mm inlet ,and rated to 300+bhp?


i can fit two tanks ,and run two sets of pipes if 6/8mm single run is not enough , just would rather keep it simple and lighter .


engines are fitted and i am at the tank and lpg fitting stage ,so thought i would ask .


oh ...open loop , mixers setup.


thanks
robert.

[Talkingcars]

I have no idea but what are you fitting this all in?

[robertXX]

this ..










thread...

http://www.rodsnsods.co.uk/forum/garage/medusa-206057





robert.

[Gilbertd]

Hmm, this is going to get interesting and, going on the success of your last conversion, will work. However, looking at those intakes are you talking 12 little mixers or doing away with the trumpets?

[robertXX]

There are 12 mixers in there gilbert

[Gilbertd]

'kin 'ell!!!!!

[rossko]

You are going to have to use 8mm for the long run - restriction is proportional to length as well as bore.
You could use a single "large" shutoff at the engine bay, and tee off 6mm pipe to each reducer.
I would not entertain using a multivalved single tank, use a four-hole type.
Consider slosh when planning tank style/mounting.

[robertXX]

thank you rossko , appreciate the info unfortunately finance dictate i'm stuck with reclaimed multivalve donuts , sounds like i have to use two tanks ...bummer .

[Gilbertd]

Robert, I'm going to blame you. The wife has had to go into hospital for a few days so my boss has suggested I work from home rather than thrashing around the country, in case I need to get down there. So, while I should have been writing a report this morning, I saw your post with the link to the Medusa build and started to read. The upshot is that the report never got finished and I've just eaten my first meal of the day (or should that be yesterday?). But I have read the lot, all 45 pages of it! Brilliant project and when you start selling tickets for the initial firing up ceremony, I'll be first in the queue.

I really wish I had a lathe, if nothing else I could create lots of little bits of curly metal. In fact, that's probably about all I would create......

[LPGC]

I daren't even click on the link at this time in the morning, given Gilberts comments I'd expect be up too late reading but will be sure to look at the link soon! Really, a couple of straight 6's joined inline to make a straight 12, brilliant! Some old Yank truck V12 engines were actually a couple of V6s similarly joined up.

Didn't you say tanks (plural)? If you fitted more than one tank you could run an 8mm pipe from each tank to each R90 with T pieces joining tank outlets together, I would expect such a setup to be OK, would even expect 6mm pipe to be OK with this setup - most 250bhp single R90 setups I see run fine with 6mm tank outlets, 6mm pipe and 6mm Valtek filter solenoids on the reducer. With one tank would expect 8mm pipe to be OK on a normally aspirated mixer setup if you changed the tank valve to one with an 8mm outlet. Both cheaper than buying another tank...

Mixers must have been a pain, piping them up might still be.. Considered gas injection? Would be possible, don't know how much the mixer setup cost altogether but cost might even be cheaper - seems like you maybe made the mixers though?

Simon

[Gilbertd]

Simon, before making suggestions I suggest you set aside half a day to read the thread. He's got it cracked but I'm waiting until he gets to setting it up. After the work he did on his turbo Astra using a mixer, I have no doubt it will work superbly but it's going to get even more interesting than it already is......

[LPGC]

before making suggestions

Rob's specific questions could be answered without reading the link, my replies are similar to Rosko's and would be relevant for any similar application.

I'm sure Rob would get there without asking any of our thoughts, no harm done chucking initial thoughts about before assembly though? Example of an easily preventable regrettable situation - 'I nearly brought this up a few days back Rob but I hadn't had time to read the link then so thought best not to say anything'.. 'Would've been alright, I might have gone with that if you had, too far down the other route now though'.

Not the kind of thread we see everyday, maybe in a few months time Rob might treat us with a new thread 'Adding turbos to twin Jag engine'd LPG car'.

Simon

[rich r]

Well that was most of my morning taken up reading the thread

Fantastic work Robert! I like your approach to solving problems, and giving things a go. Just one thing that bothers me - are you going to tidy up the edge of the gearbox plate? I'm just itching to run a grinder with a flap disc over it so it's nice and smooth

[robertXX]

hi chaps , thanks for the enthusiasm gilbert , much appreciated .

simon , the mixers were around 90 quid for 12 , so not too bad , i am trying, if i can ,to make it ecu free. if i cannot get it to drive well ,and give up on the mixers , i can always do a msqrt.

my total tank situation is i have

1 donut 47litres multivavle
1donut 42 litres multivalve
1 cylinder long and thin , 70 litres. 4 hole.

cursed luck dictated that the cylinder was about 5cm too long to fit in the chassis rails , otherwise i would have used that like a shot .

i have a friend up in glasgow ,that has said i can have his ex jag 60 litre donut and attendant fittings , but i won't get that till end of may due to transportation complications.



both donuts are full i think , the 47litre one weighs 49kg... i was wondering if i was getting old as i hauled it around before i weighed it .

i'm now thinking , maybe the thing to do is , mount the 47 litre tank , buy and put in a 6mm to 8mm converter ,run 8mm to the front ,then t it with a 8 to 6 and 6 .and then run 6 to each cut off/vap . as suggested . then if and when i get the 60 litre i can swap that in with a 8mm multivalve. its the same footprint as the 47 litre, and there's loads of headroom .


i could put the 42 ,and the 47 one above the other , but that's a lot of weight , and getting a bit high up for good c of g also its behind the axle so not good either , if i could have used the cylinder, it would have sat behind the seats , and been nice and central too. ,also needless to say its immaculate .



simon, funny you should say that , i do happen to have a huge 88lb turbo , hanging around getting in the way ..



thanks again for all the input , very very helpful .

regards
robert



oh rich , yes i am going to cut it true with a thin disk , i left a bit proud to see if i wanted that excess as a fixing flange ofr a blast shield!!

[Gilbertd]

no harm done chucking initial thoughts about before assembly though?

That's the point though. My comment was aimed because had you read the thread you would know that he already has the mixers, has machined them to fit the throttle bodies, has made the trumpets and has no petrol system or electronics whatsoever. So the suggestion of going for injection is pointless. It would also make it look ugly with all those bits of wire everywhere and completely out of context with the rest of the car.

and I was tired and hungry when I wrote my reply........

[LPGC]

I'm just itching to run a grinder with a flap disc over it so it's nice and smooth

Similar suggestion to the girlfriend

All good stuff Rob, looking forward to reading the link and following this.

No probs Gilbert, I'd had a few cans Lots of my posts are a dry read which on reflection I can appreciate might be interpreted in some lights as criticism, by no means intended... Thinking about tech seems to put me in matter of fact mode!

Simon

[classicswede]

Mixers and injection put differnt demands on the liquid side of the system. As you are on mixers 8mm feed pipe T'd off to two 6mm lines to each R90 will work fine. The issue you might have is with the Multivalve, ideally you want a high flow 8mm valve but might get away with a standard valve adapted to 8mm. With a 4 hole tank the BFC (service) outlet valve is the one to use. If you were on Injection 8mm line could be marginal and the best bet would be twin tanks with twin 8mm lines.


The biggest problem you will have is getting a decent idle as the air speed stalls at lower revs on each cylinder. You will want the older model R90's with the spring on the idle screw as the later ones without the spring struggle to allow enough fuel through on idle

[classicswede]

I'm sure you will like this little Volvo engine

http://www.sweet16.se/wp-content/upload ... G_3182.jpg

and a lot more pics and info here http://www.sweet16.se/

[robertXX]

Mixers and injection put differnt demands on the liquid side of the system. As you are on mixers 8mm feed pipe T'd off to two 6mm lines to each R90 will work fine. The issue you might have is with the Multivalve, ideally you want a high flow 8mm valve but might get away with a standard valve adapted to 8mm. With a 4 hole tank the BFC (service) outlet valve is the one to use. If you were on Injection 8mm line could be marginal and the best bet would be twin tanks with twin 8mm lines.


The biggest problem you will have is getting a decent idle as the air speed stalls at lower revs on each cylinder. You will want the older model R90's with the spring on the idle screw as the later ones without the spring struggle to allow enough fuel through on idle

thank you CS, i have two r90's , identical to each other . the sensitivity screw has a spring , the tickover bleed has no spring ...pooh!??


i'm guessing , but i wonder , if tickover is a problem , whether i can modify the bleed screw ti to allow greater bypass.


i have ordered all my connectors , so they should be here this week hopefully . i have made the tank mount , and buffed up the 90's a bit .


now i am trying to design a good method of connecting the vaps to the mixers , 6 per vap.


i have various options , one is a 22mm copper rail with all the mixers into it equidistant . and the vap into it with both feeds spaced appropriately for best distribution .

next is a 3 into 1 manifold , one for each vap outlet ,then 3cyl per manifold .ideally connecting them fujrthest pulse away ,so 1/6...2/3...4/5..


my favourite , is a vessel , with feed in the bottom ,and snaky 6 pipes out the head .so its got a medusa theme , but im worried about response time , transients would theoretically suffer with a greater dampening reservoir . i don't know if this is a real problem .

research continues.


oh by the way chaps ,thanks again for the positive reaction , most encouraging

robert

[Gilbertd]

i have two r90's , identical to each other . the sensitivity screw has a spring , the tickover bleed has no spring ...pooh!??

If they have a 10mm and an 8mm adjuster, they are the older ones, if they have a pair of 6mm adjusters, they are the newer ones. You should, even with your setup, be able to set them up with the idle bypass screwed fully home (but don't quote me on it......).