Hotwire injectors

sowen · Post by **sowen** » Fri May 29, 2015 7:16 am

I think I have an issue with some of the injectors on my SD1 not flowing equally, some of the plugs are sooty and others clean. I've got a spare set so will swap them over as it doesn't cost me anything to do apart from time. I'm curious as to what the maximum power can be had from them?

I have an Audi V8 engine (approx 250bhp) which I intend to fit in the future that has Bosch injectors fitted, but will need new fuel rails to make the installation into the SD1 neater. What has just gone through my mind was whether the hotwire injectors would be suitable to be retrofitted into the Audi V8 if I was to spend the money and have them professionally cleaned?

Is this a silly thought and should I forget about it now?

DaveEFI · Post by **DaveEFI** » Fri May 29, 2015 12:38 pm

IIRC, all the hotwire injectors are the same regardless of engine size on standard engines. Although TVR etc may fit bigger ones.

You can do a rough check on their condition by removing the fuel rail and injectors complete and pressurize it. If you have sooty plugs, I'd guess one or more is leaking. Does the fuel rail hold pressure with the pump stopped?

You can also do a rough test on spray pattern. Use a bit of blotting paper and pulse them one at a time. You should see a nice round blob of fuel.

Eliot · Post by **Eliot** » Fri May 29, 2015 5:15 pm

All TVR's ran standard injectors - albeit at their very limit (100% duty) on the the 500 engines.

SimpleSimon · Post by **SimpleSimon** » Fri May 29, 2015 10:26 pm

Yep stock inj's on Lucas Hotwire TVR V8's

stevieturbo · Post by **stevieturbo** » Fri May 29, 2015 11:12 pm

Hotwire's are bog standard Bosch configuration. Very very common injector fitment.

So it would depend what the Audi has, but very good chance they'll be a straight swap, especially if they use the normal Bosch 2 pin timer connection.

sowen · Post by **sowen** » Sat May 30, 2015 9:23 am

Thanks all, maybe not such a stupid question after all

I'm on a very tight budget on all my projects now, so anything I buy really has to have a good justification. The Audi fuel rails were damaged on removal of the engine, and are a bit over-complicated for what I want, so the plan is to buy some universal billet fuel rail stuff and use Aeroquip style fittings to join it all together, looks better too

. I'm not planning on trying to extract mega power from the Audi lump, near standard output would be more than adequate for what I want and a set of proven good hotwire injectors should be fine for me.

Baracus · Post by **Baracus** » Sat May 30, 2015 12:14 pm

If we're talking about the stock green band injectors, they're 230cc/min.

They can flow enough for about 270bhp on a sensible 80% duty cycle & about 320bhp running them flat out (all figures @ 3bar)

You can of course turn the fuel pressure up as well, they seem to work fine at 3.5 bar.

sowen · Post by **sowen** » Sun May 31, 2015 9:05 am

Baracus wrote:If we're talking about the stock green band injectors, they're 230cc/min.

They can flow enough for about 270bhp on a sensible 80% duty cycle & about 320bhp running them flat out (all figures @ 3bar)

You can of course turn the fuel pressure up as well, they seem to work fine at 3.5 bar.

Thanks

I guess I've still got a lot of reading to do...

DaveEFI · Post by **DaveEFI** » Sun May 31, 2015 9:34 am

Don't know if you've found Stan Wiess's site - it gives you just about everything you need to know about injectors including calculators.

http://users.erols.com/srweiss/tableifc.htm