I made one for a 4 litre Ford down in Vic on LPG. Made it from 10mm aluminium all round and it had three seperate runs of welding on each join.....that sucker is going nowhere. It wasn't just a straight weld, it was weaved for the ultimate in penetration considering the application. It looked similar to my "petrol" plenums even with a taper towards the rear and bellmouthed one-piece runners. The biggest expense is the materials and gas that goes into welding something like that and and then you throw in the time to do it all. Not a cheap excercise, but as you may know, you get what you pay for. Ariel

i'm running one of these in the rear of my plenum http://www.compperformancegroupstore...&Category_Code (http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=FS&Product_Code=54002&Category_Code)

....or you could just do that, easily adapted to any half decently fabricated and welded plenum

or u just make 2 plates that bolt together, weld one to plenum, and clamp a piece of coke can between them, any big back fire will split coke can open, thatshow alot of supercharged cars are

excellent idea! i like it

wont a thin peice of tin bust with the low to mid 30psi boost pressure

Quote: Originally Posted by jdcustom [View Post] or u just make 2 plates that bolt together, weld one to plenum, and clamp a piece of coke can between them, any big back fire will split coke can open, thatshow alot of supercharged cars are ive heard of people doing that but never actually seen anyone use it, like graham said u wouldnt think that a can would keep its structure holding 30+psi of boost would u? i think what cuz posted up is the go, il definately be grabbing one of them when i get my plenum

considering it has a limited surface area, the amount of pressure it could hold would surprise you...very different if you made the whole plenum out of it. as we have seen from other products on the market, it not necessarily what you use, its how you use it and how you put it all together. I have some pressure testing of other products coming up which will prove the point.

http://www.kenlowe.com.au/_borders/Superc4.jpg http://www.racecarparts.com/images/1471mani.jpg

Yeah, a very small surface area can hold a lot of pressure. You simply design the manifold with a repairable weak point.

Quote: Originally Posted by Kursed [View Post] 1. gap your plugs right (for gas) 2. get the timing set up for gas 3. make sure u dont get any air leaks into the intake system after the AFM 4. richen up the mix of your gas/air running rich is always better than running lean question what kind of gas sytem are u running sorry dude u never run a lpg but at the 100 percent correct a.rs or as close as possible it will burn so ****n hot at richer or leaner mixtures as for the plenem just get a alloy one u wont blow it up , if the tunes spot on it shouldnt back fire eny way and as long as the plemem has been made well it will just pop a cooler pipe off im about to start doing my vl on straigh lpg turbo i no a few thing to get some good gas flow and make hi power so eny thing i can help with just send me a pm also my finding with those blast plates are that they will open up under hi boost , or they wont even open after a back fire

finally someone with some sense.....it seems some gas "experts" think it is normal for a car to backfire. I have personally seen what one of these "experts" has done to a plenum of mine and trust me, a backfire is not a normal event that should be expected or accepted or should be fixed with bandaid solution of a 10mm plate manufactured plenum.

Quote: Originally Posted by ISL33P [View Post] finally someone with some sense.....it seems some gas "experts" think it is normal for a car to backfire. I have personally seen what one of these "experts" has done to a plenum of mine and trust me, a backfire is not a normal event that should be expected or accepted or should be fixed with bandaid solution of a 10mm plate manufactured plenum. alright tell that to Paul gas-747 car tuned by arguably the best tuner for gas accidentally put in the wrong plugs on a service and lost his front bar due to a backfire, your telling me he should of used a light construction plenum instead? it didn't cost me any extra to get my plenum made out of 10mm alli so why wouldn't i build my setup more robust? suxgas, holds the record for the fastest vlt on gas, he's had a backfire that blew a plenum off the car SMFRY another quick genuine streeter had a vacuum leak he didn't notice backfired and split his plenum, bad tuning? no, backfire on gas yes if you don't design a plenum to cop a backfire on gas your an idiot in my book end of story whether you cop a backfire or not

I am not going to comment on what others do and how they try and solve their challenges.... You are not getting the point....prevent the problem, don't try and fix its effects and the right tune up is the way to go. If you have all the right diagnostic and logging tools that gives you plenty of data to understand what is going on, then the problem should be solved....now if you can't interpret that data, maybe its time you realise and see someone who does (dyno tuners are a prime example of this with a simple a air temp sensor and afr meter and they think they are tuners.....no sir-ee, and we know how many of them are out there and how many engine rebuilds they cause) It comes back to my bug bear abour the automotive industry, if you can not provide the customer with what they want (which reliability is always going to be one of them along with performance), don't waste their time and more importantly the very hard earned dollars and you don't have to look too far to see these either.

Quote: Originally Posted by ISL33P [View Post] I am not going to comment on what others do and how they try and solve their challenges.... You are not getting the point....prevent the problem, don't try and fix its effects and the right tune up is the way to go. If you have all the right diagnostic and logging tools that gives you plenty of data to understand what is going on, then the problem should be solved....now if you can't interpret that data, maybe its time you realise and see someone who does (dyno tuners are a prime example of this with a simple a air temp sensor and afr meter and they think they are tuners.....no sir-ee, and we know how many of them are out there and how many engine rebuilds they cause) It comes back to my bug bear abour the automotive industry, if you can not provide the customer with what they want (which reliability is always going to be one of them along with performance), don't waste their time and more importantly the very hard earned dollars and you don't have to look too far to see these either. i agree 100% with studying the effects and preventing them from re-occurring but to think you'll never ever cop a backfire on gas is arrogant, a decent custom plenum can range from $800-$2500 to replace one after what can sometimes be a simple cause is an expensive exercise I'd prefer to be safe and allow for some contingency in a design

if ur going LPG and never expect to have a backfire then ur ods are WAY against u. no matter how good a car is tuned even something as little as the gas convertor diaphrams getting a split in them etc can cause a backfire and u wouldnt even know unless u check over everything 100% after every 50kms u drive it lol everyone on LPG has coped some sort of backfire in there time. iv seen heaps of plenums split open like a tin can!

There in lies my point, in the event that the diaphram splits, why not solve this problem? Why does the diaphram split? Can a better diaphram be purchased or made? Hey I will be the first to admit me and lpg don't know each other well (I hate greenies lol) especially when there are fuels like E85 available maybe not as readily or cheaply, but it just comes back to my point about fixing the problem, not the outcome. Paul what measures do you have to save yourself a split plenum, or whatever, incase of a backfire. I would personally hate to be driving around in a car that may backfire and cost me any number of parts and dollars every 50 km's....talk about paranoia. Ok I know the EPA and dollar saving is a big driver to convert to lpg but really what other advantage is there? It certainly doesn't perform any better compared to petrol and performance is really what everyone is about, regardless of street, strip or track?

Quote: Originally Posted by ISL33P [View Post] There in lies my point, in the event that the diaphram splits, why not solve this problem? Why does the diaphram split? Can a better diaphram be purchased or made? Hey I will be the first to admit me and lpg don't know each other well (I hate greenies lol) especially when there are fuels like E85 available maybe not as readily or cheaply, but it just comes back to my point about fixing the problem, not the outcome. Paul what measures do you have to save yourself a split plenum, or whatever, incase of a backfire. I would personally hate to be driving around in a car that may backfire and cost me any number of parts and dollars every 50 km's....talk about paranoia. Ok I know the EPA and dollar saving is a big driver to convert to lpg but really what other advantage is there? It certainly doesn't perform any better compared to petrol and performance is really what everyone is about, regardless of street, strip or track? Because it may split while you are driving? Better diaphrams.. they are made as durable as they can while still being flexible.. Maybe before saying "Just do it better" you should understand how it all work, i know you have incredible knowledge in plenums and most things automotive, but you have said youself that you arent knowledgable when it comes to gas.....

exactly why i was asking the question.....you never know if you never ask. What are they currently made out of? How do they try to prevent them splitting? How have they improved this to prevent it? I mean once every 50km's is a scary thought...although I know this may be slightly exaggerated, but still not a nice feeling to have floating around in the back of your head. Apart from that, what do you think about the rest of my post? I am yet to see a car with similar hardware to what is almost the norm these days to your petrol powered rb30 be outperformed by a lpg powered rb30 apart from km/litre

i think LPG has the capability, but the hardware people using isnt good enough Vapour injection (and liquid injection once the bugs are sorted) will be the answer. It's like stepping up from the old carb powerered holden v8 to an LS1 ---------- Post added 04-06-10 at 09:46 ---------- plus km/L isnt all that great, you're using about 30% more gas than fuel