Stag 300-6

[xj8user]

Hi, I haven't posted in a while: sold the jag but now looking to LPG my 03 SAAB 1.8t 9-3, I have the chance of a second hand stag 300-6 ecu can this be used for a 4 cylinder engine? I am familiar with the stag range as had it in the xj8. Guess I should change my used name it may confuse
I plan to fit the system myself and see that stag have new software version has anyone used it yet?
Thanks in advance for your help/replies

[rysiontko]

I don't think that you can use 6 cylinder ecu in place of 4, because it will generate errors and will not work properly if at all. Have you checked how much for stag 300-4?
I have it, it is quite good.

[xj8user]

Hi Thanks rysiontko,
No haven't looked at price of 300-4 as I was looking to transplant a used system in my Saab, but I will keep looking and saving cant afford £1000 for new one yet.
Does anyone else have a definitive on whether a stag 300-6 can used for a 4 cylinder just by setting the software at 4 cylinder?

[rossko]

I expect it could be used, but an ECU on its own is pretty useless.
If it is a "kit", any reason to think the injectors would be up to the job? (probably won't be, 4-cyl turbos are demanding)

[xj8user]

Thanks rossko,
No it is a full kit which I think is a Stag branded as a Motogas 300-6 ecu. It is rated at 200hp and was fitted to a BMW 728, my Saab is the LPT 150hp so assume it will be able to deliver enough gas? I am a qualified engineer and have been working on cars since my teens and have a reasonable understanding of modern car electrical systems, but find out something new every day, usually through forums like this.
Are there any major problems in fitting to a turbo car? I have used the AC software before and it is tweak-able.

[rysiontko]

Probably I was wrong as according to polish forum you can put there even 8 cylinder ecu and then just mark how many cylinders do you have. Sorry for missleading.
Motogas is AC dealer in the UK, but their website is "under construction".

[rossko]

Gas injectors are rated per cylinder. Even transferring a 6-cyl kit to a 4-cyl car of same power could go wrong ; you need to know the injector type/rating.
Vaporiser is rated overall; no reason to assume it was adequate in its last home, check before purchase.

Re-branded ECUs often go beyond a sticky label, and require special software for setup, if you can't get that its a terminal problem. I've no idea if thats the case here. This might be useful
http://www.motogas.com/downloads3.html

Injectors and vaporiser/regulator both wear and have a service life.

[xj8user]

Thanks again guys,
I will no doubt be on the problem page when I buy a kit and start fitting.
Its refreshing how helpful people can be on good forums

[mat_fenwick]

Am I right in thinking that purely rating injectors is bhp could be potentially misleading - for example if an injector is rated at 30bhp max, surely the flow rates are going to be massively different on a 120bhp 4 cylinder vehicle returning 40mpg versus one returning 20mpg. Obviously the consumption at full throttle is likely be be closer, but is the answer simply to avoid anything that is marginally specced?

[xj8user]

Hi Mat,
I guess if an injector is specced by output it doesn't matter about full throttle (up to a point) as this is a function of both ecu and calibration? And the calorific value of both fuels means that one returning 20mpg is either running way over stoichiometric point or should be returning way over 120hp?
I think what rossko was trying to say to me was that I needed to make sure; I either bought new injectors or made sure the ones I got second hand were in good condition and were ok for the output I required.
Hope this is correct

[lazydocker]

The ECU will be fine... My first Stag conversion was using a 300-8 ECU on a 6 Cyl car because it was all he had in stock at the time. The newer Stag 300 ECU's are up to 8 cyl

But, the Stag 4 kit's are pretty cheap TBH... By the time you've bought all the new pipework and fittings you may as well get a full kit with a new warranty