Has anyone ever tried water injection?

[spunkymonkey]

No, this isn't a "do miracle economy boosts work?" question. It's about Sheila and her pinking.

As I mentioned on jer thread she seems to be running a compression ratio of about 10:1 thanks to a replacement cylinder head in the past. Standard on these was 8.5:1 and the highest production version of the engine was 9:1 so her current setup is a little on the high side. She also pinks like crazy, even on 97 RON fuel and the timing retarded by up to about 6 degrees (by which time she's beyond gutless!)

I'm hoping that once I've done a little light work on the ports / chambers she won't do it any more because of the better breating and denser charge she should have to play with. If that doesn't work, then my only real choices are to remove the head again and drop the CR (which I'd rather not do), buy some TEL and dose the fuel up to 100+ octane, or find another way.

The only other way I can think of is water injection, which has been used in aircraft engines for a very long time for exactly this problem (anti-detonation). You can get (expensive) kits for your super-turbo-intercooled-nitrous-afterburning hot-hatch but these seem to be written up more as marketing gimmicks.

So, has anyone ever played with squirting water into their manifolds with a bit of washer pipe and a bucket*? ;D




* It'll probably be a bit more technical than that if I try it - obviously a bucket without a lid would spill in corners

[stefan]

Suppries by the pinking at 10:1 compresion with modern fuel Joe my old spitfire 1500 engine ran 11.2:1 using 98ron shell optimax without retarding the timing at all and my Firenza ran 12:1 on the same fuel retarded 1 degree

Still both had road/race cams and ported heads and the Firenza big valves and 48 Dellortos so you may be ok after the head work.

[spunkymonkey]

From what I remember of my old one of these, they were always a little prone to it in this form. On Sheila someone had also added an air-valve spring to the carb so she was running richer than standard - best guess on that was to try and reduce the pinking after the head was changed.

Given that she's been averaging about 32.5 mpg overall (compared to 29mpg according to Autocar) with timing retarded and an enriched mixture, it would be nice to get her set up so she runs happily on standard settings and see what she can do

[pauldaf44]

I seem to be getting similar to that out of mine. It also runs better with 97ron fuel on 95 its gutless and jerky under load. Running 97 its as sweet as anything, I have also noticed it runs much better on Castrol Valvemaster rather than the redex stuff that I put in the DAF. Interesting that the castrol one is supposed to increase the octane of the fuel. That might be worth trying. Incidently are you looking to go to Stonleigh on the 7th if so there will be others there including mine that you could compare her with.

Paul

[spunkymonkey]

Not sure she'll even be back together by the 7th, Paul. Before that happens she needs to have her ports ground out, her manifolds matched to them, valves ground in, the exhaust gently modified (for quietness, not power), general tidy and paint of oily head bits and putting back together.

As for comparing, her performance isn't bad apart from the pinking (she'll just about top 80) and putting super fuel in makes no real difference, so it's fairly sure to be the CR that's doing it (10:1 on an engine that was designed for 8.5:1 is a little bit high).

If I could just get her to not pink with the timing back where it should be - 7 degrees redarded is a pretty big performance hit - I don't think it'd be fair to put her up against Bruce

[dafdaffer]

stef's got a herald 1300 engine in my garage ;D if you want that as it seem to have grown roots ( id love to make a real comment but i have most of my rubbish at his house) ;D not that i can give it away ;D

my mates dad used to play with water injections and it does work.
he used copper pipe wound around the exhaust manifold from a res under the bonnet, capillary action sucks up the water and turns it to steam as its injected into the carb, well so he says ;D

[stefan]

Almost forgot about that engine, not alot of use to me now is it

My spitfire would not run on 97ron fuel but ran spot on with shell optimax which is 98ron

[spunkymonkey]

Mmmm. If it's still not a lot of use to you in a few months when money and space might be better .... ;D

[stefan]

No problem joe I can bring it to a show, we can load it into betty and you can transport it back

[daf44]

hi joe.

it all depends on how much water you want to feed in.

easiest way is to get a cheap airbrush. mount it securely so the spray end is just into the top of the carb (?tie to air filter element). run a pipe to a jar of water mounted on the side of the carb with the water level about 1/4" below the level of the nozzle.
the airflow over the nozzle will pull the water through and vapourize it. the flow can be adjusted by adjusting the nozzle (same way you adjust paint flow). that way you can play about with water flow to find a flow rate that works best (hopefully).

works well and does help keep the piston and valves clean.

good luck and have fun playing.

paul44

[spunkymonkey]

Feb 24, 2010 17:09:36 GMT stefan said:

No problem joe I can bring it to a show, we can load it into betty and you can transport it back

From the look of my valve seats I may be leaving an engine-sized space in the boot at Lichfield. With Betty, Sheila and Isabel all going (at last count) we could always split the load between them ;D

[spunkymonkey]

Feb 24, 2010 22:49:44 GMT daf44 said:

hi joe.

it all depends on how much water you want to feed in.

easiest way is to get a cheap airbrush. mount it securely so the spray end is just into the top of the carb (?tie to air filter element). run a pipe to a jar of water mounted on the side of the carb with the water level about 1/4" below the level of the nozzle.
the airflow over the nozzle will pull the water through and vapourize it. the flow can be adjusted by adjusting the nozzle (same way you adjust paint flow). that way you can play about with water flow to find a flow rate that works best (hopefully).

works well and does help keep the piston and valves clean.

good luck and have fun playing.

paul44

Cheers Paul. It may be academic with my valve seat problems (but I love a challenge ) but certainly sounds like a good way to test it out if needed - I even have the cheap airbrush already!

[daf44]

hi.

john. statistics on water injection are the same as browns gas generators.
"official" sites claim up to 600% increase in economy and you can make it yourself for £25.

some people swear by it. others just swear AT it.

if the parts are there, it is worth trying as there is nothing to loose.

I thought you may have a airbrush floating around somewhere Joe. you are the same as me, with bits and pieces of EVERYTHING somewhere in the garage, "just in case".

paul44

[spunkymonkey]

I must admit to being very sceptical about the more outrageous "benefits" of either. Even nitrous injection doesn't make more power unless you squirt in extra fuel at the same time so hoping for water to transform an otherwise stock car is a little optimistic to say the least.

But the anti-knock properties of water are very well researched and documented - mainly in regard to aircraft engines running obscene amounts of power on take-off.

The general approach was to run higher compression and more ignition advance, using the water to cool the combustion chamber and slow the flame-front so detonation is avoided - end-gas heating is well proven to be a limiting factor in both compression ratio and timing. I've already got the extra compression by accident so making it work properly seems to make sense.

The other approach, which was used by a lot of manufacturers before on-board knock sensors were practical, is to run rich under power. But, because it's a rich mixture, all the extra fuel does is cool combustion. I can happily turn a richer needle for the carb to do that but, with a choice of extra petrol at over £5 a gallon or water out the tap, I like the idea of water.

May even be able to run a slightly weaker needle if it's successful and save the extra fuel the maker allowed