Technical Uno turbo injector upgrade

[benjy_a]

I have a kit car with a MK1 Uno turbo engine in it. The engine has many mods but it is running on standard fuel injectors.

Went on the dyno at Interpro (Bristol) today.....managed 191 bhp and 187 ft/lb which is bloody good but this was only at 5633rpm!!!

however...unsurprisingly....beyond 5633rpm it starts to go lean. This is with the injectors wide open. So....as expected I need bigger injectors to be able to get it driveable. This will push it nicely over 200bhp - not too bad at all!!

So the same old question again....what injectors will fit straight into my MK1 but give me 10-20% higher flow rate? Anybody? I know this has been asked many times but I can't find a definitive answer...

Also can anybody remind me what the difference in flow rate is between the MK1 and MK2 injectors, and if the MK2 injectors will fit onto the MK1 fuel rail?


From searching this forum I have found that the following may work:
1) Saab 9000T injectors (although quite a few people think that these are just too big) - what is the flow rate on these?
2) Punto GT injectors - are these a straight swap?? And how much bigger are they??

Many thanks,

B.

 

[benjy_a]

Ok so from some more reading it seems that the standard MK2 injectors will not fit onto a MK1.

Also the MK1 injectors are 280 150 704 rated at 170cc/min.

Could I just order something like Bosch 280 150 706 (214cc/min) which apparently are used in the Porsche 928. How would I know if these fit?
Are all the bosch injectors the same shape?

 

[benjy_a]

Ok I have had a look at the injectors much more closely and the only difference between the MK1 and MK2 physically is that the MK1 has a barb for the hose to clamp onto....and the MK2 has an o-ring type connector.

I have managed to take all the bits off of a set of MK1 injectors and fit these to a set of MK2 injectors. I intend to get some adapters machined so that I can fit hoses to these. Has anybody tried this before? I read somewhere that people have in the past simply removed the o-ring and clamped a hose onto this style injector.....?

Alternatively I think I have worked out that ideally I should have something like 280-150-712 injectors (214cc/min). Are there any of these availble with a barb / hose type connector and if so what are they from? All the ones with this part number that I have found seem to have an o-ring fit.

Cheers,
B.

 

[alexGS]

Hi benjy_a,
Welcome to the forum! Your three posts so far have a high usefulness-ratio
I was feeling sorry for you that no-one had yet replied.

It sounds like a lot of power - standard turbo?

If you fit larger injectors you would have to tweak (maybe electronically-intercept and modify) the signal from the airflow meter, otherwise the running at anything less than full power would be worse.

Perhaps another solution would be an extra (5th) injector? I'm guessing you've considered this but you didn't mention it. The extra injector could be mounted in a solid elbow in front of the throttle housing. The cold-start injector from an old Bosch K-Jetronic setup could be an easy option, as it sprays with a constant voltage or with pulses (I guess that all injectors do this, however, but on the K-Jetronic the voltage was constant I believe).

Control might be a bit crude but at least it's only going to be an issue at high engine load. You could use the factory pressure switch (the 0.86 bar one on the end of the plenum?) to trigger a circuit that increases the injector duration with airflow meter signal, or maybe you could simply turn it on and hope for the best.

Jaycar in Australia sell relevant control circuit kits. www.jaycar.com.au

Cat number KC-5387 is an electronic boost controller, which apart from the obvious use (PWM switching of a boost control solenoid) I believe could switch that extra injector instead. Obviously the main input would still be the AFM.

Alternatively, Cat number KC-5385 is the fuel adjuster. It's function is to intercept the signal from the AFM and allow you to adjust it up/down at 128 load points. This means you can effectively 'trick' the standard ECU into supplying less fuel - useful when you fit those larger injectors. It's probably not as ideal as a complete new engine management system, but it's a lot cheaper and gives you complete control over the fuelling curve.

To program either of the above, you need the KC-5386 handheld controller. This has a two-line LCD so you can see what is going on as you make the adjustments. It can be used in the car, no separate power supply required.

I bought these kits but haven't got around to building them yet. I also have the KC-5375 duty cycle meter, which I intended for using to check that my fuel injectors weren't maxing-out like yours. Of course, I haven't got around to building that either!

If you choose 'KITS' from the first drop-down menu on the left of the Jaycar page, and 'AUTOMOTIVE' from the second drop-down, you can browse the whole range. There would probably be another solution to the fifth-injector problem - you could use a fuel mixture indicator (requires Lambda probe) and the add-on for controlling intercooler water spray (could turn on the injector instead?)

Cheers,
-Alex

 

[benjy_a]

Thanks for your reply Alex!

I have now found a product which enables me to run more modern injectors in the Uno MK1 engine so that is one problem solved! (some guy on ebay sells adapters so you can connect a hose to the top of an o-ring style injector)

So....I intend to buy some Bosch 0 280 150 712 (240cc/min) injectors to put in....

My tuning guy thinks that he can get the engine running ok with these injectors just by playing with the fuel pressure and AFM spring tension, of course it will be running pretty rich in the lower rev range.

The Jaycar kits you mention seem interesting....do you think that they will really improve the fuelling that much? I had been considering investing in the Megasquirt system which is also quite cheap but looks like you need a lot of experience to set it up!

Are there any reviews or any more information about the Jaycar fuel adjuster kit that you know about?

Cheers,
Ben

 

[alexGS]

My tuning guy thinks that he can get the engine running ok with these injectors just by playing with the fuel pressure and AFM spring tension, of course it will be running pretty rich in the lower rev range.

The Jaycar kits you mention seem interesting....do you think that they will really improve the fuelling that much? I had been considering investing in the Megasquirt system which is also quite cheap but looks like you need a lot of experience to set it up!

Are there any reviews or any more information about the Jaycar fuel adjuster kit that you know about?

Yes but no, I fully believe that the Jaycar kit will do a much better job than playing with the spring tension will but I don't know of third-party reviews. Jaycar do a book, 'Performance Electronics for Cars', which is basically the instructions from all of the kits so that you can read about them before you buy. The instructions in turn are actually articles from Electronics Australia/Silicon Chip, the two Australian magazines whose projects get turned into kits by Jaycar and (more in the past) by Dick Smith Electronics (which is now more like Dixons than Maplins, if that helps you follow what I mean )

Yes, I have also heard about Megasquirt and sure, if you can get it for a similar price, that's a good option.

Anyway, keep us posted. And keep searching the forum too - do Advanced searches, in the Uno section only, SteveNZ is a likely user to search for posts from, though he might be a bit busy at the moment to reply to a private message.

-Alex

 

[benjy_a]

I really like the look of the Jaycar kit as an easier way to actually set things up.....I have some limited experience with building electronics kits when I was a kid...

Alex did you say that you actually have the kit? If so how hard does it look to put together? I think maybe I would consider buying one already made although it is quite a lot more money!

Cheers,
B.