The 'E' Type Forum

Due to the fact that the original Etype airbox set up is widely considered restrictive, i was just about to order an ITG barrel/dustbin air filter but wanted to throw an idea out first.
I have a tuned up Lambretta that has had the airbox drilled to pull more air into the motor while still retaining the standard look, it looks good & works a treat.

So: do you think it would help to de-restrict the air induction on my S2 if 20 x 8mm holes were drilled to the rear (not visible) side of the original dustbin airbox?

I would still run the standard filter inside the drilled dustbin thus providing a greater volume of clean air to the motor while retaining a standard looking engine bay - & saving ?250 over the ITG filter in the process.
This could also prove safer as i assume that the metal airbox would be more fire resistant than a foam filter.

Used original airboxes are readily & cheaply available so the car could always be put back to standard at a later date if required.

The triple SU's have already been fitted with UX needles - which are the recommended size for running the ITG filter so should also be fine with a drilled airbox.

Could this work - or have i missed something?

Thanks,
Bert.

Bert

The air box limits engine power (by 6% according to Jaguar) because the inlet pipes are too small. If you wanted to retain an original look you could remove the existing pipes and weld on bigger diameter ones which would also mean the air box works as intended in sourcing its air. Obviously drilling holes is an easier option and would probably work just as well. Be aware though with increased air flow you may upset the SU's so you might need to install richer needles.

Holy airbox Batman!



Now that's what I like - a free upgrade (apart from adjusting the jets of course)

You look at the three ports to the carbs and the two similar sized holes into the airbox and you think well that's just obviously not right. I guess when the car's back together again I'll find out.

Remember although you have three carbs they are all drawing at different times, so you do not need the hole(s) in the box to be the equivalent area as the three carb inlets. The air box also cuts down induction noise which can be quite tiresome on long journeys. It is a balance between power v noises v filtration.

I think???

The only concern I would have with the colander look is the air will be sourced from the engine block which means it will be very hot. Jaguar used the two long inlet pipes to get as cold air as possible into the carbs.

The paper OEM element is not waterproof either. Not a problem most of the time but it would lead to rich running in serious water spray conditions even with the lower shields present I suspect. I guess for people who don't drive in the wet it's not a big deal though.

However, the statement that looking at the three carb chokes and comparing them with the twin pipes is 'obviously not right' is simplistic to the point of ignorance, sorry.

As stated, the priorities of a car maker are not the same as the priorities of a hobby car owner fifty years later. But even so, Jaguar were perfectly well aware of what they were doing and there is nothing 'obviously not right' at all. Saying that there is, makes a bigger statement about your understanding of air flow through an engine than it does about Jaguar's choices. Have you even worked out the respective cross-sectional areas or accounted for the boundary effect or the plenum effect of the filter can and the triangular carb plenum, or anything like that? 'Course not - there's no need, it's obviously wrong...

No offence but you can't just say stuff like that and not be corrected. You might as well say the cross sectional area of the two resonator outlets is 'obviously not right' either, and drill your exhaust pipes every which way.

For the two nanoseconds per day that your foot is pressed into the carpet and the engine is at or beyond red line, you might have a point. But even then it would only be true if the rest of your car is in perfect order and delivering to the max. The other 99.99% of the time your holes are a waste of a good air cannister but I guess if it sounds sporty that's all that matters. The placebo effect has sold a lot of go-faster goodies down the decades.

I stand corrected!

Skiday,
All is not lost......I reckon that, with some carefully handcrafted brass flaps over the holes, controlled by varying strength springs, you could get it to play "Theme from Dixie" as you go from 5000rpm to 5500...
Norman

It's been a while since my last post here, but now that the car is on the road I can say it's going great. It is hard to make a direct comparison as the car was off the road for 15 months, and it's gone from auto to manual. I would say though, it feels more responsive to the throttle, but it would now as it's manual anyway. It is no louder that I remember it, and it's still a lot less of a tiring noise than my MGBGT, just lusty and lovely! I also cannot see it will draw hotter air than standard, or that it stands to get any rain splash in it.

All in all, I stand as Edith Piaf did; (Non, je ne regrette rien)