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Fuel Injector Location
karlak - 26/9/11 at 08:50 AM

I know it's a subject that may have many different answers and opinions - Probably covered before as well.

But, I need to make a decision on whether to have the Injectors for the Duratec,l direct into the Head or into the Throttle Bodies.


Are there any particualar advantages to one method or another ? I am thinking that Direct to Head would allow a little more "headroom" under the bonnet - The TB's angle upwards as they leave the Head.


Any thoughts ??

r1_pete - 26/9/11 at 08:58 AM

I did read somewhere during designing the setup for my Jag, the best injector location is to have them spray onto the back of the inlet valve, and looking at the pattern of the injectors I planned on using they were set to spray onto the back of each of the two inlet valves in the 24v engine they were from.

So I'd go for direct in head.

SeaBass - 26/9/11 at 09:00 AM

The further away from the head the better ultimate "top end" performance. Closer to the head for better performance at low engine speeds.

Production vehicles site the injectors firing onto the back of the valves for economy and emissions reasons as most driving will be low RPM and cruising.

Most compromise at mid lengths firing into the air stream after the butterflies.

There are massive texts on induction length tuning and injector positioning.

big-vee-twin - 26/9/11 at 09:17 AM

My injectors are into the head, I have blanked the injector ports in the Motorbike Throttle bodies.

Bear in mind that the Duratec head design is basically a race design and has very good flow characteristics, it one of the many race bred features of the engine that Ford/Mazda built in.

Do you have your throttle bodies yet, I'm using GSXR 750 from a 2000/01 bike which split easily and a Fast Dan Duratec inlet manifold.

I have a spare set of bare GSXR 750 throttle bodies in like new condition if you want to buy them going on ebay soon.

Kev

tomgregory2000 - 26/9/11 at 09:52 AM

run twin injectors and get them set up for maximum power everywhere in the rev range

will121 - 26/9/11 at 11:52 AM

quote:
Originally posted by tomgregory2000
run twin injectors and get them set up for maximum power everywhere in the rev range


ive got twin staged injection on a zetec silvertop with orignal zetec in sandwich plate and secondary injectors in GSXR750 TB's i was going to set it up with switchable maps to see any advantages but never got round to it, i would say look at space available including airbox/filter and see whats best or stick with the inner setup

BaileyPerformance - 26/9/11 at 04:33 PM

I would go outboard, in the throttle bodies if i was you, a mate of mine is running a race duratec in a autograss car, 290BHP with inboard injectors, 303BHP outboard on engine dyno. No noticeable negative effects, low end power better if anything with the outboard. He used Jenvey individual tapered throttle bodies.

I have done tests on my chassis dyno on a 2008 Hayabusa powered autograss car, throttle response was better with the injectors further away from the butterflies, but again i used the jenveys not the bike stuff, no real power gain but crisper throttle. I also tried 8 injectors, may have been worth the extra effort on a road car but not required on a race car, idle and slow speed drivablity not important for a racer.