I'm gearing up to re-do my set up and going with the xcessive LIM is part of that. Seeing that it has 4 injector ports and they offer a 4 injector rail, I was thinking about consolidating. Is there anything wrong with deleting the primary rail and just going with the single 4 port rail? The plan is to run 1000/2000. I want to do this for no other reason than to further simplify my set up. A single rail would make me very happy. Just want to make sure I'm not overlooking something...

 

I want to say that the primary injectors are located where they are for atomization purposes. Changing your primary injection location to the secondary rail could cause issues or complications. I'm not 100% sure though..

 

Yeah, I think that's the deal. It would probably effect low load/idle mixtures if you had it up higher in the intake tract.

Thinking about it, at higher engine speeds you have faster airflow through the intake manifold to bring the fuel into the engine. Without that faster flow you could just be wetting down the manifold without fuel getting into the engine.

Dale

 

these drawbacks sound dangerous..... its unfortunate. i would really like to go to a single rail since now i know it exists lol. if its possible that i will be dealing with delivery issues, i dont want to play with it. i kind of do actually but also not really lol.

buuuuuuuuuut if anyone has tried this, i would like to hear some feedback

 

I really do like that simplicity of this idea. There are some things you could do to combat the low rpm issues like changing injection timing, playing with fuel pressures, etc to help it work better. If no one has done it, then you could be a pioneer of simplicity if you can get it to work appropriately. I'm sure Mazda played with this idea and there's probably an SAE paper somewhere that gives their reasoning on the matter. Carb set ups don't give great atomization and they're high up on the port if that helps.

 

If you have a non PFC ecu, you can fire the primary injectors sooner than stock.

With it and a warmed up engine running, you could vary the primary firing until you optimize it.

 

R26B paper talks about it. the higher up you put the injectors the worse response gets, and efficiency goes down too, you need more acceleration enrichment.

 

I tried this years ago. I was able to tune it okay, but off throttle response and cold start were never perfect. I ended up bugging me enough to go back to two fuel rails.

 

How "not perfect" are we talking? Also what injectors and what ecu?

 

I've built a couple race setups (not street, ever) with primaries in the secondary locations and can say with confidence that if you're running newer injectors (ID or similar and real EV14) you can get a perfectly acceptable tip in and idle pattern for a ported rotary @1000 rpm (probably lower but I never bothered to try, again, not street). Now, if you want it to behave EXACTLY like stock with stock ports and idle at 750, support PS and/or AC drag, I'd avoid trying.

 

damn.... youre saying all the right things lol. bosch ev14 is what i am going with. went with 750/2200 instead of 1000/2000 on a power fc. the motor is also street ported.

you have me on the edge of going for it....

 

I installed an Xcessive LIM and 4-injector fuel rail (with primaries blocked off) about 10 years ago, using 4x ID1000 injectors back before the 2000's and 750's were available. I had a fabricator friend add a flange on the end of the fuel rail for mounting a Honda-style adjustable FPR (similar to what is now available on the Radium fuel rail), which resulted in very simple fuel line routing. The idle and throttle response were OK but I had to run the idle a bit richer and the low-RPM throttle response was not quite as good as stock primary injectors in the stock primary ports. For a track car that spends most of its life above 3000 RPM I think it would be fine. For a car that needs to feel stock it would be noticeable, I drove mine that way for about 5 years and eventually added a Full Function Engineering primary rail with very small injectors (around 350 cc/min) which was a big improvement for cold idle and low-RPM throttle response. Some day I might try to swap 2x ID1000's in the primary fuel rail to see how that runs, but for now I'm very happy with my current injector & fuel rail setup.

 

I'd add that I'd never try to dial it in on a PFC either.

 

Based on you guys information, it would seem it may work out but also not lol. It would cost some money to experiment with this. I will try it out one day but not anytime soon. Going to a single rail would be beautiful to me but it seems the trade off in operation isn't worth it.......... maybe lol

it's so tempting to just go for it but in the case that it annoys me, I won't drive the car and it will sit until I fix it. I'm not ready for that. Still very much accepting input though.....

thank you guys

 

A setup using this rail and direct-mount pressure regulator would have one less fuel line than the setup most people run on rotary engines. It would also avoid needing a mounting bracket for the FPR.

Fuel Rail, Top Feed Conversion, Mazda 13B-REW Secondary

DMR, Direct Mount Regulator

 

I saw that as an option. It's nice but I like the aeromotive prominatley displayed front and center