Jump to content
The mkiv Supra Owners Club

Extra injector instead of 550 replacements


Barry

Recommended Posts

Whats the deal on this?

 

As 550cc injectors are both hard to get hold of and stupidly overpriced when they are available, could I just leave the 440's in place and fit a 7th injector to the inlet?? I'm assuming this would give the additional fuel required for a 'reasonable' increase in boost.

 

The only problem would be controlling it.! I have an Apexi SAFC fuel controller, can these control an extra injector?

 

Cheers

Link to comment
Share on other sites

You can get fuel computers, check out the AIC or Rebic (I think), that will do this job. It's far from ideal though, as you have no real idea how well the fuel is distributed across the cylinders. Plus, with the cost of buying a whole new computer just to trigger your injector, buying the injector, modifying the inlet tract to mount it, modifying the fuel rail to feed it, you could have probably bought a new set of injectors of the correct size and done a much better job!

Link to comment
Share on other sites

I think the GReddy Emanage can with the appropriate harness, but I expect it would be pretty hard to set up. You can always get Power Enterprise 650cc injectors from somewhere like Takakaira in Japan. They're high impedance too so you don't need the resistor pack. They're still expensive though, about 80 quid each I think, plus delivery and VAT and import duty if you're unlucky... :music:

Link to comment
Share on other sites

Originally posted by Barry

Whats the deal on this?

 

As 550cc injectors are both hard to get hold of and stupidly overpriced when they are available, could I just leave the 440's in place and fit a 7th injector to the inlet?? I'm assuming this would give the additional fuel required for a 'reasonable' increase in boost.

 

The only problem would be controlling it.! I have an Apexi SAFC fuel controller, can these control an extra injector?

 

Cheers

 

BAD BAD idea! Why? Inlet manifolds on injected cars with injectors near the ports (most modern injected engines) are designed to flow AIR, and air only. Add a denser mixture (fuel and air mixed0 and the shape of the manifold results in some cylinders getting a richer (or weaker, however you want to look at it) mixture than others. Assuming a wide band mixture readout in the exhaust you only read an AVERAGE mixture, number 1 could be mad rich, number 5 crazy weak, for example. It's virtually impossible to get an equal fuel mixture to all cylinders like this, which makes them very suspect. Do it properly, with larger injectors. If you go VERY large you need a GOOD ECU, as the pulse width modulation on cheap ecus means the mixture can go from too weak to far too rich just over one "graduation" in the map. This is why the seemingly bargain ECU's are not really such a good buy. It's a minefield and you get exactly what you pay for, go into with eyes wide open or you will end up with an engine that runs like a dog, and maybe blows up!

Link to comment
Share on other sites

Thanks for the feedback guys, some good info.

 

The one area of an engine I know little about it fueling and fuel injection. I've just ordered a book on how Fuel Injection works so I can learn a little more about it. I'm still stuck in the dark ages of carbs.!!!

 

Thanks again.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.