jono Posted January 10, 2016 Share Posted January 10, 2016 didn't take much or long to satisfy this curiosity things in mind were apparent engine efficiency design be that the air volume from intake valves to throttle plate be same as the engine capacity another concept in mind is that for propane/lpg fuel of the older vapour fogging systems is the smaller the volume of the inlet the better so the system can change the lean rich demands of the engine sooner. another, having gone for a greater EA82 spfi volume I have sort of got some bogging down operation over my modified EA81 carb inlet manifold with both cases the gas carb sitting atop the manifold. Also have done a remote gas carb with it then feeding quite an air volume [ 2 feet of 56mm pipe]before the throttle plates and then std intake volume. Also know of a propane turbo set up where the gas carb was six feet away before the turbo on a straight six 4.0 So, some of these set ups have defied the match the air volume to engine capacity - and I guess one is for petrol/gasoline theory. I am about to try the spider intake over the non spider. I taped up all the holes and started filling up by 500ml beaker and got to about 2900ml before I sprung a leak just as I got to full. Then the water log air section add 100ml per head, then we have the air volume of the heads above the valves and a little behind the plate of the throttle body. I'd estimate 150 to 200ml of each mpfi head sooooo might be about 3500 ml or cc of total inlet volume ! That's twice the 1800cc ! Be a case of suck it and see - all without a dyno all I have is feel of seat of pants, a few times from 0 to 62.5 mph of a yet to be checked speedo 17 seconds, or 0 to 50 mph 12 seconds Quote Link to comment Share on other sites More sharing options...
skishop69 Posted January 13, 2016 Share Posted January 13, 2016 The size of the manifold has nothing to do with engine displacement. Well, almost nothing. It is more about flow and velocity. IE: Volumetric efficiency. You need high velocity without compromising flow (volume) to keep the fuel properly atomized. Quote Link to comment Share on other sites More sharing options...
jono Posted January 13, 2016 Author Share Posted January 13, 2016 well, yeah, totally agree with your comments, I may not have explained best that I had read some authority on engine building about how the intake volume should be [at least? ] or close to engine capacity but this sort of starts to get a bit out of hand thinking of big engines such as ya 351 ci huh It may be for efi too ... just thinking of snorting twin or triples on straight fours and sixes sitting snug against the head sort of ignores that theory i read and as with efi, nothing is gonna fall out of suspension until the injectors. My fuel of choice not really fall out either. This thing stomps, third and fourth of five gears are strong. 0 to 80 no faster. 60 to 100 kph [36 to 62.5 mph] 7 or eight seconds in third. Third gear is fun, hmm, so too fourth. And towing a 250kg trailer - hardly felt it was there I am now curious of the figures quoted for the NA spider manifolded EA82 engines - just in LHD XT? Anyone got them to compare over the other EA82 engines ? This could be an interesting manifold to try a side draught carby slapped on the back - could be a dog ! I find the LPG gear is very adaptable to all sorts of manifold applications so makes it easier to tinker - screaming out for a turbo now !! Quote Link to comment Share on other sites More sharing options...
skishop69 Posted January 13, 2016 Share Posted January 13, 2016 Gotcha. True that with FI you don't have to worry about the suspension issue at all. The real key is finding the most efficient velocity/volume combo keeping the straightest line possible to the valve port given the space you have to work with. Carb set ups bolted straight to the head with only a short, straight tube work best for carb apps. Pretty much the same for FI. The problem is space, configuration and cost. Now you have multiple carbs or TB's hugely raising the cost and arrangement to keep them in the space allowed. I've been trying to figure the best set up for a twin or quad TB set up for a port injected EA81 I'm going to build. Quote Link to comment Share on other sites More sharing options...
jono Posted January 13, 2016 Author Share Posted January 13, 2016 thinking of where I can put the space saver spare now front passenger flor would be better than my home entry foy-air something that came to mind when you mention quad port - Triumph 2500PI of late 60's and early seventies did use three units that bolted to the head. Each was of cast alloy and had a throttle plate per cylinder and injector hole I am certain ?? They'd be a nice air flow match to a four pot 1800cc Quote Link to comment Share on other sites More sharing options...
skishop69 Posted January 14, 2016 Share Posted January 14, 2016 Yeah, I've had a few ideas. Whatever I do, I'm going to do some massive head porting, put in bigger valves and make it a true split port intake. I'll most likely end up with motorcycle throttle bodies and a wicked rod linkage system with the TPS mounted on the fulcrum. I've built 400hp small block, regular pump gas engines back in the late 90's so I've got some good ideas to squeeze 200hp out of one of these. The computer models say it will make it, but we won't know without a dyno run. Quote Link to comment Share on other sites More sharing options...
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