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Injectors For K20 Stroker Build

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I'm new to building engines. Son is an apprentice mechanic who got suspended while this covid19 has displaced the business where he was employed. We bought a K20Z1 from a wrecker and are going to build the 2.3L stroker using a Brian Crower kit.

Getting a kit means the parts for the build are pretty well sorted out for us. The problem I have is with finding a suitable set of injectors. Calculating the required flow using online calculators puts us requiring approx 550cc injectors for 250 whp on Oz 98 octane. Son wants to future proof this NA build by also considering using E85 later on.

Recalculating for E85 means we could cover any realistic HP increase by getting a set of approx 750cc injectors. It seems almost everybody is using ID1050X injectors which makes me wonder if the injectors would be optimal as they would only be run at half duty cycle flat out.

Can anyone comment from experience if the ID1050X would operate from idle thru to high rpm on this build. The motor will have cams, IM and headers and be running a 11.5:1 CR, but is also a daily driver which will see occasional track use.

I see Deatchwerks offer a 750cc and FIC do a 775cc injector that may fit the K20 but finding these injectors locally in Australia is impossible. Any suggestions on available injectors would be much appreciated.

The only issue with using oversized injectors is if the ECU is capable of very precise small injection times for idle. I use 1050x injectors on 2L Mazda MZR engines (making about 220 hp normally aspirated) with a MoTeC M1 series ecus with absolutely no problems. Having a high-flow injector does allow you to play with injection timing, which you can't do when the injector is open for a 60+% duty cycle.

Thanks for the input David!

The car is a 2005 Honda Integra Type S and it has a Haltech Platinum Pro fitted.

I'm not a tuner but both dead time and flow rate can be set for injectors. I cannot see any provision in the ECU Manager software for providing correction tables for operation in a non linear region. I'm guessing with the ID1050X, idle fuel injection timing levels may be in a non linear range for such a large injector.

The thing is I dont know if the Haltech would operate the injectors anywhere near as good as your Motec M1 at idle and part throttle. So It seems unless anyone can offer any info on Haltech Platinum Pro and the ID1050x injectors it might still be that a set 750cc injectors is the easiest way to tune.

Any suggestions on injectors of that size available off the shelf in Oz or is it time to order from the USA once again.

EDIT: I opened a support ticket with Injector Dynamics so hopefully they can inform me if the ID1050x will work at idle and part throttle ok!

An idling engine can use more fuel than you may realise - some vehicles have a fuel readout and I had a NA 2 litre, 4 cylinder that was using around 1.5 litres/hr at a ~850 rpm idle. While that may seem a little high, it works out at ~6.25cc/min per injector.

With a stroker, with cam's, you can treat that as a minimum and, as the throttle may be open more for a higher smooth idle and because of charge loss through overlap, it may be significant.

Their 1050 cc/min rating is at 3.0 bar - you could also drop that to 2.5 bar for a reduction in fuel flow while still having an adaquate spray pattern. On that, when checking frow ratings, pay attention to the pressure they're rated at, you may also have the option of a smaller injector run at a higher pressure - perhaps even having a inlet manifold reference to lower it at high vaccum, like idle, but full pressure at low vacuum, like under full throttle?

Gord, Do you know what the pulsewidth was for the injectors at idle on the Mazda motor?

If I knew the pulsewidth required for stable idle then I could look at the ID pulsewidth vs flow chart to see if its in a linear region. ID provide info here http://injectordynamics.com/articles/low-pulse-tech/

Your right about me not realising idle required a decent flow rate. I'm running oem fuel pump and plan to upgrade the pump when the stroker is built, but will still keep the in tank system and regulator so 3 bar will be the fuel pressure.

I'm looking forward to hearing back from FIC and ID injectors to see what info and recommendations they have.

In the meantime the block is in the workshop about to be sleeved and I'm working out in consultation with my son what are the best parts we need to build the motor.

As a lot of the parts will be coming from overseas sources it could take sometime to get them in so hopefully we can get it right the first time. Buying the Brian Crower stroker kit means we cant stuff up the right combination of parts for building the short block. Custom pistons in the kit mean the CR and bore fit can be ordered to suit.

Things like injector type and size are a bit harder to get our heads around finding out the best to get for the stroker motor. The ID1050x certainly get praised all over the internet forums, just unsure about the size so hopefully the tech support people will provide the info thats needed.

EDIT: I tried some basic math to calculate micro litres/pulse and came up with approx 14uL/pulse for the 6.25cc/minute at 850 rpm idle. That would be around a 1.75ms pulse using the info on the link I gave above. If we add 1ms of dead time to it we get 2.75ms needed for the pulse, which is at the injectors lower limit in the usable linear region of the ID1000 used in the link. If its about the same for the ID1050x then it looks like it will probably be fine. I realise my assumption and calculation is based entirely on one link and is probably wrong, but at least I now have a better idea of what may be needed.

Looks like the ID1050x injectors would suit the stroker engine without any problems. I contacted ID and got the following reply from Mitch Mixon.

"Sure, the ID1050's would be no issue on that engine at all. You could use four ID1050's on a 1000cc motorcycle engine just fine, so this engine is definitely fine. It'll run as well as a stock injector once its tuned."

I also got a response from FIC about the suitability of their 775cc injectors and was informed they would be perfect for the stroker for the hp figures I provided (250-280WHP).

Also got feedback from Deatschwerks on their 750cc injectors (Bosch) and informed they would be the right choice for the motor's requirements.

Hmmm, now to choose which ones to get!