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Post by CHR15 on Jun 24, 2013 21:00:20 GMT
no idea where i got up to on the old forum with this, but anyway; decided to take it off the road and have a crack at drag racing (probably wont be working till next year though) rough (eventual) spec - 1340cc, 8~:1, injected, ms v3, stick coils, air shifter, long ish swinger, plenum with injectors in + single throttle body (just to see how that design works) bb turbo (dunno what yet) wax loaded intercooler. probably more stuff i dont really remember. 1340 block modeled up: lump of ali as i dragged it out the workshop after 7 months of being under a dust sheet predictably it had pissed oil everywhere. (probably cos i bought an aprilia to replace it!!) ripped all the wiring and crap off it, i'll make a complete new loom to suit the new setup bare pile of good stuff tank or not... fuel cell will be bolted to the frame underneath the false tank. will have the pump and fpr bolted to the cell and run a deadhead rail setup so theres only one fuel connection from the cell to the rail, the use a drybreak q/r fitting and a superseal connector so i can remove the tank with only 2 connections and a couple of bolts. i figure that the first/second time i build this i did it on the cheap a bit, so this time im going to do it properly so its easy to work on and doesn't piss oil out of literally every single joint lol. also, plenum: ive changed it a bit since that screenshot, to make it a bit less turbulent. the injectors point directly down the tracts and the inlet length is adjustable. (eventually i'd like to get it set up with servos or mini linear actuators so the length is variable depending on revs, but thats a long way away) i'll run a single throttle body off a duke or prilla before the plenum. be interesting to see how well that setup works, with nothing in the inlet tracts.
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Teresa O.
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Reg: May 31, 2013 18:51:42 GMT
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Post by Teresa O. on Jun 25, 2013 6:47:49 GMT
hey Chris, welcom back...
doing a quite similar setup right now, with a single throttlebody before compressor though..
anyway.. please don't do a deadhead type of fuelrail... i recently did some testing on my homebrewed injector test-bench with some concerning results in deadhead mode (unequal distribution, pressure drops etc..)
Cheers..!
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Post by CHR15 on Jun 25, 2013 7:30:58 GMT
would be interested in seeing what tests / results you got!
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Teresa O.
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Reg: May 31, 2013 18:51:42 GMT
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Post by Teresa O. on Jun 25, 2013 7:52:26 GMT
the general analysis showed that on standard fuelrails (like on injected suzooks with rail inlet between cyl 1&2 or 3&4)the enormous flow at WOT would suck dry (reduce pressure) on the small end of the rail. A deadhead stystem will probably never be 100% for a charged engine on full chat. Thats why I then eventually decided to go inline to be safe... I guess you wont go individual lambda or individual EGT to be sure what happens..
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Teresa O.
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Reg: May 31, 2013 18:51:42 GMT
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Post by Teresa O. on Jun 25, 2013 8:01:46 GMT
and even if you do it in the way your CAD-model shows. The risk of pressure droping a long the injectors is high enough not to do it. Immagine it as fuel massflow... It won't stay the same til it reaches cyl4.. even when your goig sequential (we're only talking WOT here)
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Post by CHR15 on Jun 25, 2013 11:30:24 GMT
i'm intrigued that the problem still exists even with sequential injection.
its not too difficult to add a return line in, just means adding a second dry break connector.
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Teresa O.
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Post by Teresa O. on Jun 25, 2013 11:37:24 GMT
on MPFI-Engine WOT, high rpm, at lets say 90% dutcycle, there's no such thing as "sequential" anymore.. ;-)
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Post by mattturbocar on Jun 25, 2013 14:08:41 GMT
Chris,
Good to see you are back on here.
I see you have 2000-2003 gsxr1000 style injectors. As you have a free choice of injectors at the moment I'd suggest you go with more recent injectors. The technology has moved forward to give much nicer spray (i.e. more holes, smaller droplets). I am not sure of the terminology.
Regarding your plenum. You need to check that it will function as a pressure vessel. I've heard of a couple of designs that had flat sections that rapidly bowed and fatigued from boost pressure (10psi over a box 12in x 4in gives you 480 lbs of force).
Matt
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Post by captain chaos on Jun 25, 2013 18:37:56 GMT
(eventually i'd like to get it set up with servos or mini linear actuators so the length is variable depending on revs, but thats a long way away) i don't think the effect of this will be noticeable on a supercharged engine. Someone might proove me wrong though
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Post by mattturbocar on Jun 25, 2013 18:47:17 GMT
(eventually i'd like to get it set up with servos or mini linear actuators so the length is variable depending on revs, but thats a long way away) i don't think the effect of this will be noticeable on a supercharged engine. Someone might proove me wrong though Isn't he is going bb turbo. I thought about inlet tract length and decided that long must be the way to go. More torque at low rpm, and let the turbo deal with the torque at high RPM. I added 15cm to the inlet length as well as the length of the gsxr600 throttle bodies. No compelling evidence to prove it makes any difference though (although it is easier to get at the cam chain tensioner now!). I copied the idea from some big budget sierra cosworth engines.
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Post by CHR15 on Jun 25, 2013 19:21:38 GMT
yeah matt, i picked those injectors cos i had some lying around.
anyone wanna spec me some that are 'good'
the supercharger thing is still sort of there, ive got part of the drive mechanism built up on a spare engine, it just needs more head scratching and money thrown at it.
i have no idea if the variable inlet will make an difference, but its an interesting thing to try!
i will probably weld tie rods into the plenum, that being said the one on there now (one of dougs early ones) hasnt deformed at all and ive had it up to 1 bar for short amounts of time.
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Post by captain chaos on Jun 25, 2013 19:38:21 GMT
i don't think the effect of this will be noticeable on a supercharged engine. Someone might proove me wrong though Isn't he is going bb turbo. what is bb turbo? Doesn't matter if he goes turbo or mechanical compressor or whatever, any "blown" engine is a supercharged engine, turbo is just one way to do it. And my point is that variable inlet lengths are only usefull on naturally aspirated engines (not supercharged).
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Post by CHR15 on Jun 25, 2013 19:42:39 GMT
intriguing.
perhaps then its best to make the tracts as long as possible to aid fuel vaporization.
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Teresa O.
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Post by Teresa O. on Jun 25, 2013 19:42:56 GMT
bb=ballbearing...
and CC is absolutely right..
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Post by trenchy on Jun 25, 2013 20:32:49 GMT
Matt, I'm sorry but anything that effects a na engine will effect a boosted engine even more, just because you are flowing much more air or air/ fuel past the obstruction or whatever it is. Shorter fatter runners WILL give more top end at the expense of bottom end, and long thin runners the opposite.
A lot of people think that to get around bad design you just up the boost, but that is bad practice. Makes things a lot more likely of going bang.
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