cool air

The other day when it was damp and cool my car ran very well. Has anyone got rid of the carb cooler motor unit and piped air to the carburettor from there. It should be cooler than the hot air from the engine bay. Any thoughts?

Not aware of anyone doing that, however, what should help is if you add a ducting from the air cleaner inlet down to the air scoop inlet on the side of the engine bay. That way, when running you are getting a direct supply of fresh (?) air straight into your air cleaner.

If you have electronic ignition you can get rid of the carb cooling fan. If not I would keep it in place.

The standard air cleaner can does a reasonable job of drawing cool air from the area fed by the left hand side vent. Fitting a pancake filter defeats itself if you don't ensure that cold air feed is maintained.

The X1/9 hot starting issue is due to heat soak in the engine bay evaporating the fuel in the carb float bowl. That's what the carb cooling fan is for. The carb cooling fan draws air from the fuel filler area. This air has been drawn over the engine lid and I would suggest this air is not as cool as the air forced in via the side vent.

I have a cone type filter located on that side of the engine bay which seems to work for me but my car doesn't have a carb anymore. Previously my car often failed to re-start when it was hot even with the carb cooling fan (petrol station stops) although it would always start after 5 minutes cooling down.

I think a manifold heat shield would be a good bet if the original one is missing. Would wrapping the manifold have a similar affect?

Was this evaporating fuel issue a problem with all engines which had inlet and exhaust manifolds on the same side? Just made worse by having a rear mounted engine?

I had a similar thing on an old land rover but only after driving for hours. (heat shield was missing on that also)

Also engines are meant to run better when the atmosphere is damp aren't they?

Yes, a heat shield is very useful, as is wrapping the exhaust. Front-engined cars benefit from generally good and controllable air flow into and around the engine bay, even if it is via the radiator. The X1/9 has a very compact engine bay so it is asking for heat trouble!

In older engines inlet manifolds were inefficient and the fuel tended to drop out of suspension and just lie in the manifold. The heat coming off the exhaust was beneficial as it helped to vapourise the fuel, hence the inlet and exhaust manifolds were often on the same side.

Cold, damp conditions are beneficial as the air charge is denser and the water vapour helps in raising combustion pressure while at the same time cooling the combustion chamber and reducing the tendency for knock to occur. This is the principle behind water injection.

Waffle over.

Thanks Rachel I never knew the hot manifold was actually beneficial.

so as the original post is kind of concerning dampness... I have always wondered this:

If water injection was used on Spitfires in WW2 for emergency power and it can be used on tuned cars. Why is it not used more widely for improved fuel economy/power?

Is it solely the issue of carrying water around or is it a matter of longevity? OK i just went to read Wikipedia about it...

Don't get me started on 'Browns Gas' - was that a scam? I always wanted to write to Top Gear to do a study on it...

The difficulty with use in production cars is that the owner would have to keep topping up, and you would need to use soft water for longevity. However water injection has lots of benefits for forced induction engines.

Brown's gas is a load of nonsense! Splitting water into its components will use more energy than what can be released when recombining them - so an engine running solely on water is a thermodynamic impossibility.