guys im looking to see whts out there in regards to cast forward facing plenums.......im looking at trying to find one to run with my lpg setup.....i want a true fwd facing like a cpc....the reason i wanna go cast is im afraid if im running big boost 30+ and i cop a backfire from the lpg it will peel open like a tin can......any sugestions or thoughts....what are people useing on this site that run lpg........ cheers guys

good thinking i had a backfire and blew open intake manifold and smashed the starter motor

Few people have run box style setups with LPG and they work fine - honestly if you get a decent backfire, cast or not something is gonna give. Welded ones are much easier to repair :P Id use a JD or Rajabs presonally for LPG.

why do u not just eliminate the the issue of backfiring all together it's not that hard with most gas systems i fix them everyday on taxi's and doing a gas and turbo conversion on my vl atm

How

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

Running aftermarket ecu looking at making 400rwkw at about 35psi I have no afm, running apa tank twin pick ups twin lines twin b2 converters 440gra t/b

ok well richen it up and gap your plugs to 0.7

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 i'm guessing you've never tuned a big boost LPG car before with regards to the manifold graeme feel free to come check out my old JD plenum to give you some ideas i put a burst plate on the back which was made of a perspex if i copped a backfire it would blow out, replace the perspex and away you go again i also got it made out of thicker aluminum 10mm to be exact

yeah thats right, having a plenum full of LPG thats under intense pressure; its only a matter of time before it goes pop. But if your conservative on the tune side it should be alright - just have to maintain it all properly.

Quote: Originally Posted by Morgz [View Post] yeah thats right, having a plenum full of LPG thats under intense pressure; its only a matter of time before it goes pop. But if your conservative on the tune side it should be alright - just have to maintain it all properly. i've seen a tune first hand sitting on the rich side of a tune 3 run ups all the same mixtures and 3rd run was a backfire that blew a cooler pipe off so hard it shattered a front bumper personally i'd shy away from a cast item, depending on design of course but if a cast manifold explodes and fails it will shatter into small pieces at least with a fabricated manifold it will tear but hopefully no material goes flying thats my 2 cents on it anyways

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 Oh is that how u do it. Lol. Jk I've only had one backfire but not due to tune. Coped a vacuum leak and it leaned out. It split on the weld and cost me like $80 to get re welded. Suxgas designed an awsome plenum for LPG. U should pm him if ur serious. ---------- Post added 17-05-10 at 15:51 ---------- Quote: Originally Posted by vltrb-0 [View Post] i'm guessing you've never tuned a big boost LPG car before with regards to the manifold graeme feel free to come check out my old JD plenum to give you some ideas i put a burst plate on the back which was made of a perspex if i copped a backfire it would blow out, replace the perspex and away you go again i also got it made out of thicker aluminum 10mm to be exact Perspex sounds like a good idea. How did u mount the perspex? Any pics?

Quote: Originally Posted by vltrb-0 [View Post] i've seen a tune first hand sitting on the rich side of a tune 3 run ups all the same mixtures and 3rd run was a backfire that blew a cooler pipe off so hard it shattered a front bumper personally i'd shy away from a cast item, depending on design of course but if a cast manifold explodes and fails it will shatter into small pieces at least with a fabricated manifold it will tear but hopefully no material goes flying thats my 2 cents on it anyways that wasnt a white vl with a kit was it:?

Quote: Originally Posted by Epitaph [View Post] that wasnt a white vl with a kit was it:? nope that was mine lol, pauls has done it too but his was from wrong plug choice when he serviced it, thats what he told me anyways i can 100% confirm the car was running rich as all **** 3 runs identical last resulted in some nice arse backfire plenum copped it like a champ 10mm alli ftw

well clearly i'm wrong backfiring must obviously fix itself And 2 bar clearly isn't big boost and none of u have actually said anything that will actually stop the motor backfiring talk about the blind leading the blind

even well tuned petrol engines running 30psi will backfire - u can here em occasionally going down the track, and just because its tuned on a dyno correctly and everythings fine there doesn't mean you wont have problems once your on the track.

LOL i saw a white vl with a kit reeling off 360rwkw then blow a pipe of, smashed the front bar to bits!

Quote: Originally Posted by Turbro [View Post] Oh is that how u do it. Lol. Jk I've only had one backfire but not due to tune. Coped a vacuum leak and it leaned out. It split on the weld and cost me like $80 to get re welded. Suxgas designed an awsome plenum for LPG. U should pm him if ur serious. ---------- Post added 17-05-10 at 15:51 ---------- Perspex sounds like a good idea. How did u mount the perspex? Any pics? 10mm perspex enough to hold 40+psi of boost, 8 holes even spaced around the same radius and a fracture line created on the inside of the flange, if it blows the idea is it punches the piece out around the fracture line drops the manifold pressure and saves you some additional damage ---------- Post added 18-05-10 at 14:43 ---------- Quote: Originally Posted by Kursed [View Post] well clearly i'm wrong backfiring must obviously fix itself And 2 bar clearly isn't big boost and none of u have actually said anything that will actually stop the motor backfiring talk about the blind leading the blind do you tune your car or just leave it with the tuner and come back when its done? ---------- Post added 18-05-10 at 14:45 ---------- Quote: Originally Posted by Morgz [View Post] even well tuned petrol engines running 30psi will backfire - u can here em occasionally going down the track, and just because its tuned on a dyno correctly and everythings fine there doesn't mean you wont have problems once your on the track. yeh exactly right morgz, when i hear it im like if that was on lpg there would have been a nice small explosion then haha

lol just fit a burst plate will be the only way to ensure nothing goes wrong thought this thread was about plenums, not what makes things go bang? LPG backfires happen, its just a fact of life. yes you can tune them out, but what if the sun and the moon align on the correct date and you get a backfire? burst plate will solve all!

Quote: Originally Posted by misk [View Post] lol just fit a burst plate will be the only way to ensure nothing goes wrong thought this thread was about plenums, not what makes things go bang? LPG backfires happen, its just a fact of life. yes you can tune them out, but what if the sun and the moon align on the correct date and you get a backfire? burst plate will solve all! i agree they make spring loaded burst plates for blower manifolds try summit racing