EFI upgrade of k-jetronic on GTSi

At idle getting the fuel fully vaporized and mixed is a challenge so most everyone times the injection pulse to spray right after the intake valve closes. That lets the fuel hit the back of the hot intake valve and sit on the hot port walls as long as possible getting all of it vaporized. That makes the engine the cleanest and most efficient it can be

That is not ideal for making hp though because you are not using the vaporizing fuel to cool the incoming air, so for hp the goal is to spray into the moving air charge and pick injectors large enough so you don't need more than about a 35-40% duty cycle. There is usually a table to control what crank position injection starts or end at under different conditions.

.....which then means the ideal injection pulses are REALLY short and hard to control. To fix that you need higher resolution in the fuel math, better accuracy in the processor, and fuel pressure and tamp sensors, and fully characterized injectors and and ecu that can accept the additional data.

Or you size the injectors for more like 80% DC to make low power control easier since that is where a street car spends 98+% or its time and just don't think about the couple % of hp you might be giving up

 

Forgot the injector angle. For the street the injectors want to be as close to intake valve as possible and pointing toward the valve as best as possible. It was never clear to me why the odd angle on the 2V setups but they changed it with the QV and 328.

That said, you don't always get the injector placement you'd prefer.....and it doesn't make a ton of difference. You can end up with an idle that is higher or slightly rough but how would you ever know on a 1 of 1 install? I built a few blower intakes for QV engines and had no choice but to point the injectors at about ax30 degree angle to the port wall but they ran and idled well...they probably would have struggled to meet OEM emissions but I never tested that

 

There are different spray cone angles but that is the shape of the cone, not an angle of the cone to the axis of the injector.

There are also dual cone injectors for 4V setups but I've never tried them.

 

Yup...

Many many times like Mark.

The odd 2V injector angle is due to the angle of the runner in the head because the water jacket and ports are different from the 4V.

I made injector rails for the modern injectors by hand bending and brazing stainless tubing, machined cups and distro blocks. Loads of work and unfortunately on the costly side. The 2V was/is the biggest PITA to make rails for.

Also made adapters so that nothing was modified on the oem part. The wrench in the works is that injectors today are molded plastic, the old steel bodies are custom and touch more expensive. The 4V gets the love as bmw uses a Bosch injector with an Xt nozzle, in other words the injector has a long reach nozzle like the CIS one.

Pics to follow.

I'm working on development of a replacement intake runner set for the 2V to utilize molded injectors and a straight forward rail. There would also be the replacement of the intake plenum. That's been sorted thankfully.

We are utilizing more and more 3D printing and currently team with a facility that prints for DoD contracts.

Ok I'll dig up pics

 

I have, they work great and are a touch easier to control afr during idle and cruise. WOT makes zero difference.

 

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I make extensive use of additive manufacturing as well

 

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Join the dark side!

I really really wanted one of my boys to get into material sciences... They didn't. That area is growing due to additive mfg. It's gotten to where it's possible to print circuits in parts....... But that's still in dev.

 

Image Unavailable, Please Login This one's still my favorite... Nothing a little bmw M6 tbs can't handle
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Are you working on a QV? If so maybe? As I said, I've never tried them so I just don't know how much difference they would make. I do my 4V v12 engine idles smoothly at 700 rpm with 1000cc single cone injectors so I've just never seen a reason to play with stuff like that.....but who knows what in missing out on?

 

Dang it... Just got that...

Does welding count?

 

The split cone spray wouldn't do much of anything for the 2V. But that is the correct Bosch body for getting the nozzle into the air stream.

But there's a catch.. Always is. The 2V uses a threaded insert to hold the stock injector. The new molded injectors will require an adapter that can hold them and screw into place... Yeah haven't sorted that out as yet. The later 4V uses an internal clip that makes those easy to adapt.

Std single cone spray is fine for the 2V in any case.

 

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Not familiar with the skyline setup... That would be neat if they do.

 

It does count!

Whack off the old wrong bung than weld up the hole and new more useful bugs on. Maybe a couple more to bolt the fuel rail to and DONE.

Then add a couple bugs to the TB mount a TPS to and that's done.

Keep it simple.

 

It's funny I was just thinking... Can you believe we've been at this for 20yrs or more... Talk about when a hobby gets outta control

 

In a couple months I'll be at 16 years on the same stupid engine

 

I don't know that I'd call it "the same engine"
Iterations and order revisions, beta #X...

But think of the education! You hold a doctorate in one man R&D on a shoestring budget.. write a book on it, the highs!, the lows, the suspense!