Air box Elan S4 with weber

[StressCraxx]

May I suggest removing the screens on the trumpets, drive your car and see if the performance improves.

Then install the airbox, drive it again and see if there is a change.

Shorter horns may make it run slightly leaner at high rpm.

[syrius]

I will try this air box .

A+
Serge

[RedS4]

Who sells that one and how much is it?

[syrius]

This man [email protected]
65? included shipping for France

A+
Serge

[RedS4]

Thanks for that. Does anyone know the thread for the screws that hold the box on the backing plate (Series 4)?

[alan.barker]

I hope this helps you need: 1/4" UNF 28 T.P.I. bolts, so you have a plain section (shank) under the head.
I put a spring washer, penny washer then a large rubber tap washer( centre hole tight fit on bolt dia). the rubber tap washer stops any damage to the airbox. You will need to measure for the bolt lenths because the airbox looks deeper than the original one
Alan B

[RedS4]

Thanks Alan.

[nmauduit]

Based on this thread, I've decided to enlarge a spare airbox that I had, by about 20mm towards the rear

deeper air box top

deeper air box inside

no issue in fitting under the bonnet - the black gelcoat protection layer was applied with a roller, giving a somewhat crackled finish

deeper air box installed

Now remains to decide whether this has a significant effect (psychological or otherwise) ...

[1owner69Elan]

We found that my recently rebuilt twin cam lost 7 hp on the dyno using the stock S4/Sprint Weber air box.

Thus, I had a much larger air box fabricated based upon a 26r air box as a template.

The result is shown below. I know it looks rather large in the picture. It's supposed to fit in my S4. I would think the S4 has at least as much room as a S1/S2 26r for the air box. We will see. Otherwise, modification required.

As a result of the custom air box I have a spare, brand new, S4/Sprint Weber air box backplate and air box if anyone is interested. I'm in California.

[Certified Lotus]

Who made your custom airbox? I have been looking for one to fit my S1 for a couple of years and have a whole collection of them. The S1 has a very tight fit at the air intake side of the box. Looks like this one may fit.

[1owner69Elan]

The custom air box was fabricated at Veloce Motors West (Dave Vegher) in Petaluma, California. It wasn't inexpensive. Nice craftsmanship like everything that comes out of that shop. I did the final cosmetic finishing/painting.

I hopefully will know if this fits in a month or so when the engine is back in the car. The critical area is the front end as you note where the engine bay tapers down.

As noted the shape came from copying a 26r air box, so it should not be a "shot in the dark" and can be expected to fit. Dave maintains a number of customer real 26r's for historic racing that remain on site.

[Certified Lotus]

I'd be very interested in having one made. Can you indicate the cost? PM me if you would. Thanks!

[1owner69Elan]

PM sent

[rgh0]

Thus, I had a much larger air box fabricated based upon a 26r air box as a template......

.

Looks like a very nice alternative to the standard airbox. I have done similar tests and found around 4 to 5 hp loss with the standard airbox on a 150hp engine, it would be more in a more powerful engine.

The reference to a 26R airbox intrigued me as I have never previously seen any reference to this as part of the homologated options in the period or in any of the books that described 26Rs. Dave Vegher knows his stuff and has seen many original 26Rs ( if such a thing exists) over many many years so I am sure its correct.

I searched all my Elan books and photos and could only find one period photo of a racing Elan engine bay in the 60's. it was a photo of John Miles car in the Chris Harvey book - Lotus: The Elite, Elan, Europa. That photo shows the air box cover removed to make way for the remote master cylinder reservoirs just like I have done on mine.

One of the 2 genuine 26R's in Australia that I have a photo of from the early 80's also appears to have always run with no airbox as it has the master cylinders in the same location as the John Miles car photo with no room for an airbox

I would be interested to see any other period photos of a 26R engine bay with an airbox in place

cheers
Rohan