looking good. the stock pattern looks alot better than the sard aka DRIBBLER.. hopefully the rails will accomodate 555's and 740 nismo injectors in the early style lower plenum (pre 94/95) thats my wishlist
I would assume the injectors for the later model intake plenum would be the same as the sards with the wider spray patter. Especially if thats what later model stock injectors were like. Wonder what the border injectors are like? They even have their own rail.
Fixed link... http://www.twinturbo.net/net/viewmsg.aspx?forum=general&msg_id=873035&forum=technical&dtSearch=0
Yes, the later model injectors have the same problem as SARDs... The border racing injectors set are pintle style and best suited to earlier style plenum/head ports....they do sit a little higher but the pintle style means their spray pattern is narrower....which is what is needed.
Looks like the Border kit might be the way to go, however they do say it could do with a little bit of machining to fit just right as the injector doesnt sit quite as low. But at $1300+ for just their rail its expensive. Had a quick look at Z1 and they have some kits around, wonder whether they would be any good.. Nismo 740cc kit with machined 90-93 lower plenum PE 850cc kit with machined 90-93 lower plenum But they basically just use the newer style OEM fuel rail. Machined "old style" (90-92NA 90-94 TT) lower plenum. With bosses cut to accomodate "new style" (93+ NA 95+ TT) fuel rails
this is all interesting reading and quite timely for me as i have been tring to work out what is the best set up for my motor as it is just about run in and time for a performance tune so i was going to do injectors at the same time From all the reading i have done the nismo 555 seem the go but i am keen to see what get developed with this fuel rail as i belive that the 555's could limmit my my meduim to long term plans with my motor. Now with the Spray pattern issue being talked about ( i stupidly didnt think of this) i am back to square 1 with picking injectors )
Z1 kits None of those Z1 kits will eliminate the problem of fuel hitting the plenum wall before it enters the air stream, except the border kit. Having said that, a lot of people are using these without too many issues... so the problem may not be worth worrying about.
With it just being the wider spray pattern, wouldnt it be relatively easy to get the older style heads and lower plenum machined to suit? I mean if your going to the work of getting your heads machined and ported out this wouldnt be a great deal more work, then simply use the SARD 800's or whatever you like with these aftermarket fuel rails.
Machining older heads/lower plenum If you look very closely at the two plenum designs as seen in Kuah's post I linked earlier to TT.net, you'll notice that it's not just a matter of machining... They are physically different such that you can't just machine them to be a like.. To get a similar shape to the newer style one, you'd need to add more metal onto the plenum to be able to cut a recess of the same diameter as the newer units. You'd need to buy the newer plenum/gasket, then try and machine the heads to suit... I havn't actually seen a newer set of heads, but I would hazard a guess as to say you might need to add some metal on to the older heads to make it work, as well... You could try to open up the injector port hole a little without adding material, but I don't think you'd get it wide enough to make any appreciable difference.
To me it looks like all the difference is that they have machined open the area where the injector tip protrudes into, therfore allowing the wide spray to not be hindered by the walls of the plenum. Using the above picture as an example, the older style is simply a hole which would then match up to the heads as per below. So would it not simply be a matter of machining out the heads to match what you have machined out on the lower plenum. I know theres not alot of metal there to work with but it should be able to accomodate some extra machining to do this, its not like its actually having combustion take place right in that section. The only issue would be getting a gasket to match.
I beleive the tt.net thread is right though in that the ideal solution would be to us a 95+ lower plenum and get the heads machined to match as closely as possible.
To me it looks like the lower 95 plenum would sit over the edge of the port boundary on the older head.... creating a very big leak... I don't think you can fix that with a gasket... the addition of the square bit on the newer plenum makes them quite mismatched.... At the end of the day it would be the best solution, but someone really needs to try it and see if it is feasible....
Rails etc Not sure what they were set at and I agree spray pattern will definately change with pulswidth. Not so much concerned with how much fuel is coming out but rather the spray hitting the edges of the plennum and dribbling down rather than straight through like with pintle style injectors. Andrew reckons by 3000rpm or so it would probably be OK but at idle and cruising RPM it's going to be hard to tune.. I am just going to use a pintle type injector with the new rail. No problems with spray pattern then. Exactly. And yes they will just waiting for more stock to come in so as they can hook it all up and confirm the spray patterns and everything works like it should. Gees that is alot of money considering we can use big 850cc pintle style injectors which will suit old style plennum and UAS fuel rails... Heeeeeapds of interesting discussion here but for mine the best/cheapest option is going to be to keep my existing head and plennum, use the UAS fuel rail with fittings etc, and use big pintle type injectors. All the boxes checked that way with big injectors, upgraded rail, and nice spray pattern. Exactly. Problem is definately in the eye of the beholder and the bottom line is suitability of pintle-less injectors in early plennums. It's not a problem with the rail/injector combo...
What brand 850cc injectors are you looking at because to be honest I want my build to be done right the first time and after watching those videos im a little paranoid lol
Exaclty. They're being supplied by the same guys doing the rails -should be in early next week so I'll get some pics and vids so as everyone can see the difference.
