Josh Posted September 4, 2006 Share Posted September 4, 2006 Well im new to efi etc and have a couple of questions someone might be able to answer. Fuel rails - usually one rail holding the injectors, my new motor has split fuel rails, 2 injectors on each one, what does this mean, why is it like this, benefits or downsides, any info at all on that appreciated. Plenum - What difference does size etc make blah blah, bit of info on these if people have any. Cheers Quote Link to comment Share on other sites More sharing options...
Hemi Posted September 4, 2006 Share Posted September 4, 2006 takinf a stab in dark but i think the split rail is there to help smooth out fuel flow prehap? ...actaully i dont know at all Quote Link to comment Share on other sites More sharing options...
YeMs Posted September 4, 2006 Share Posted September 4, 2006 the motor wouldnt happen to be a 2 rotor rotary would it? Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 4, 2006 Share Posted September 4, 2006 its a 2litre pinto motor Quote Link to comment Share on other sites More sharing options...
Josh Posted September 4, 2006 Author Share Posted September 4, 2006 Yea pinto, not a rotor. Quote Link to comment Share on other sites More sharing options...
Gaz Posted September 4, 2006 Share Posted September 4, 2006 Plenum size and shape mainly changes throtle response and torque. Quote Link to comment Share on other sites More sharing options...
RT Posted September 4, 2006 Share Posted September 4, 2006 for turbocharged engines plenum size isn't quite as important and n/a as the entire system is pressurized. Generally, larger the better.. some people try and design formulas for ideal sizes but they are never accurate. Plenum sizes are ususally 100% of the total engine displacement.. or more. small runners for top end torque /ie racing.. long runners for bottom end torque /ie street. basically I made mine as big as possible.. I think it's about 3.5L, and tried to angle the runners to aid flow into the pinto port which is unsually flat. the injectors are aimed at the back of the valve which is where you want it. Quote Link to comment Share on other sites More sharing options...
Burntrubber Posted September 5, 2006 Share Posted September 5, 2006 I made mine 3.2L for my 1600 because a few people told me that would be good for forced induction a bit smaller would be better for N/A from what I have been told. Quote Link to comment Share on other sites More sharing options...
OSC Posted September 5, 2006 Share Posted September 5, 2006 split fuel rails are to try and equalise pressure between your injectors to try and stop one cylinder leaning out. Quote Link to comment Share on other sites More sharing options...
Josh Posted September 11, 2006 Author Share Posted September 11, 2006 Copied from another answer I got which kinda contridicts RTs one hmmm. Unsure. from what ive always heard plenum size does matter for turbocharged vehicle a 2 litre engine should have a 4ltre chamber , diff runners will have diff effects as well as having 1,2 or 4 throttle bodys ( in a 4cyl appl.) otherwise why wuld companies like greddy bother making plenums for imports like gtrs silvias etc ( i kan tell you it aint just for wank factor ) flow is the most important charateristic of any manifold in a performance appl..also on injection rails its a common perf appl to have the exit of the rail to the reg out the centre of the rail ( or teed in between the two rails ) and run a split feed into each end of the rail or for a twin pump set up so that it lessens the chance of the end injector running outta fuel under high load. Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 11, 2006 Share Posted September 11, 2006 greddy makes them for better flow characteristics, he doesnt say/I dont know whether greddy ones are bigger Quote Link to comment Share on other sites More sharing options...
RT Posted September 11, 2006 Share Posted September 11, 2006 exactly. and he doesn't contridict me, I never said plenum size wasn't important, I said it doesn't matter as much as n/a where you require everything possible % gain you can get, so size and flow etc require more attention to detail. Same with the throttlebods, on a n/a the bigger the better as not to inhibit any flow. On turbo setups it's not so important unless it is restricting the flow of a pressurised air flowing through it. of course greddy and other performance fabricators like CAPA, Nizpro etc can design better flowing intakes for specific cars. Why is it not as important in a turbo setup?? look at it this way, say your plenum is average. You could spend $1000 on a beautiful peice of work that would flow better and gain you say 5kws. OR.. you could just crank up your boost for nothing by an extra 5psi and get an extra 10kws. see what i'm saying? Quote Link to comment Share on other sites More sharing options...
Josh Posted September 12, 2006 Author Share Posted September 12, 2006 Yea I see what your saying. Think il stick with the one I have now then, has short runners though. All good. RT do you have entry at each end and return/reg out the centre? or none out of the centre What are the benefits of running a twin pump setup and just split feeding? Quote Link to comment Share on other sites More sharing options...
RT Posted September 12, 2006 Share Posted September 12, 2006 I have a single peice rail with the intake on one end and the regulator on the other. like this: I can't think of any significant pros or cons of runnning a split rail. the short runners will mean your engine will have more torque at top end rather than at the bottom. Quote Link to comment Share on other sites More sharing options...
Josh Posted September 12, 2006 Author Share Posted September 12, 2006 what injectors do you use? Quote Link to comment Share on other sites More sharing options...
RT Posted September 12, 2006 Share Posted September 12, 2006 all the specs are here: http://www.retrotech.co.nz/capri.html Quote Link to comment Share on other sites More sharing options...
Josh Posted September 12, 2006 Author Share Posted September 12, 2006 Its just like my injectors have the rail on them like built in sorta thing where as yours sorta "plug" in to the fuel rail hmm maybe im wrong with mine, il go look at mine again Quote Link to comment Share on other sites More sharing options...
RT Posted September 12, 2006 Share Posted September 12, 2006 injectors come in all shapes in sizes.. yours look like they are some sort of factory injector setup that had them build in the the fuel rail. Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted September 12, 2006 Share Posted September 12, 2006 josh, does your manifold hold 8 injectors?? if so is there to sets of 4 with each set being of different flow capacity? Quote Link to comment Share on other sites More sharing options...
Josh Posted September 12, 2006 Author Share Posted September 12, 2006 Na just the 4 injectors Quote Link to comment Share on other sites More sharing options...
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