Alan Cesar
Alan Cesar Associate Editor
6/21/11 9:58 a.m.

Fuel injectors evolved over time, and as you might suspect, their spray patterns and level of atomization have improved with each generation. Here's what I'm talking about: http://www.youtube.com/watch?v=oxImoYMRUCA&feature=related

Guys who have played around with Miata injectors already know this; '99+ Miatas have a different shape injector body, and many have done that upgrade.

Injectors also come in different flow rates.

I recently upgraded mine and my dad's Escort's injectors to a set of EV6 units as used on the Mustang V6 and Windstar from about a decade ago. Same 19-lb/hr flow rate, newer design. We measured with a scan tool and confirmed long-term about a 5% increase in fuel economy. The electrical connectors were more or less compatible -- we had to break some plastic tabs and zip-tie the connectors down so they wouldn't vibrate out, but it worked. Some BMW E30 and Mustang owners seem to do this upgrade as well.

I recently found a crack in one of my injectors, so I figured now's the time to upgrade. I've done a lot of poking around and searching; unfortunately, the cheap and easy to find Ford injectors may not work. Miata injectors use that plastic spacer to seal the injector agains the intake manifold. Most other injectors use an O-ring. Otherwise, I think the length is the same.

So! Mazda injector geniuses! I want EV6 or newer injectors that will fit my 1.6L Miata. But not just fit: I want the same flow rate, too. I'm looking for a drop-in, no-hassle swap. No AFM tweaking, no Megasquirt, no adjustable FPR. This means injectors from a '99+ Miata won't work.

Does anyone have ideas? I think I found Ford SUV injectors with the right flow rate, but again, that plastic-spacer-versus-O-ring thing leaves me uncertain.

Strizzo
Strizzo SuperDork
6/21/11 10:04 a.m.

IIRC, the stock f150 v6 injectors were 19 lb/hr, what rate are you looking for?

Alan Cesar
Alan Cesar Associate Editor
6/21/11 10:09 a.m.

I've found varying reports on 1.6 flow rate, from 212 to 235 cc/min. That's 20-22 lb/hr. 21 lb/hr would probably do the job, but again, I don't know if the Ford injectors will seal correctly against the manifold.

Keith
Keith SuperDork
6/21/11 10:23 a.m.

230 cc at 43.5 psi is what my notes say. 1999-00 stock injectors are 238 cc at 43.5, so they should be a drop-in.

The 1999-00 runs at a higher fuel pressure, that's why most people are confused about the injector rating.

Alan Cesar
Alan Cesar Associate Editor
6/21/11 10:34 a.m.

Keith, I've been killing myself trying to find this information for months now. Hot, steaming crap, that's awesome. You are truly a god among mere Miata enthusiasts. Thank you so much.

Now I just need to find a set of those for cheap.

Keith
Keith SuperDork
6/21/11 11:38 a.m.

How to Build a High Performance Mazda Miata, page 67

Glad I could help. We have some salvage 99 injectors here for $60/set if that's the price range you're looking for.

PhilStubbs
PhilStubbs New Reader
6/21/11 11:50 a.m.

if you have the ability to tune the ecu/megasquirt then check out the acura RDX injectors. they have great atomization and can support quite a bit of power. a lot of the N/A and lower boost turbo honda guys are using them these days

Alan Cesar
Alan Cesar Associate Editor
6/21/11 1:05 p.m.

Keith, that's exactly the price I was looking for. I just called up Bill and ordered 'em. :)

David S. Wallens
David S. Wallens Editorial Director
6/21/11 2:22 p.m.

Cool. And thanks, Keith. (By the way, Alan, Keith's books should be in my office.)

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