ITB's

[Bhyde]

Hi I'm in the process of a ITB conversion onto my 1UZ Engine is stock apart from link ECU, headers & a twin pipe 2.25 inch mandrel exhaust with a cross over and of course the 50 mm ITB's. I'm thinking that the standard blue 250cc injectors will need to be upgraded???? Can anyone advise on this and if so what size is recommended. I guess it comes down to HP & tune, any information would be greatly appreciated thanks

 

[ivan129]

Wow 50mm TB's are big! Too big for a stocky. Independant TB's look great and sound great too. But are really suited for the track. If this is a road driven car you'll regret fitting them because you won't be able to shut up the induction noise. You'll also need a heap of enrichment added to the fuel table, across load, RPM & engine temp to compensate for the large amount of air entering the engine when you open all those butterflies, otherwise the engine will just bog down lean as soon as you crack the throttle open. Tuners will claim you shouldn't run your injectors above 85% duty cycle (thats 85% on and 15% off) however most will happily go to 90% for short burts. It might be best to get your engine tuned first and then work out what size injectors are really needed. Going too large injectors can often give problems with a stable idle. Without headwork, valve springs, cams and turning that engine, you will never achieve the full potential of those big TBs. Good Luck

 

[ivan129]

You can also gain a little more flow out of your std injectors by raising the fuel pressure. Assuming you have an adjustable fuel pressure regulator. Your fuel pressure should be in the vicinity of 40 - 43 PSI, lifting it will make the entire fuel map rich though.

 

[Zuffen]

If I remember correctly Mazda RX7 440 injectors are a straight plug in on the 1UZ.

I agree 50mm is way too big but the stock heads flow so poorly you will see very little benefit for all the work, money and never ending induction noise.