Amazon: Plastic airbox for twin Sus

[JDW3696]

Hello all.
So Amazon cars do an air filter collection box but they can't get the top if that makes sense. I was hoping to fit a collecting box and the a pipe feeding it with cold air. Has anyone got any ideas as to other cars that fitted collection boxes to su hs6 carbs? 140's old Triumphs maybe. Looking for a solution for them and me.
Thanks
Joe

[Derek UK]

Various B20 Amazons and 140 had these. Did you ask Rob at Amazon cars if he had a set of the plastic ones? He might have it after he has converted rally cars to his alloy box. I think the inner box does need a small amount of work to fit to the B18 carbs.

[JDW3696]

Hi Derek,
Yeah I asked. Unfortunately they can't get the lid anymore so I was looking at alternatives. I'll keep looking.
Thanks
Joe

[Derek UK]

Many of these were removed to fit seperate filters, mostly for looks. The boxes are more efficient and quieter. Being as they can supply the carbs with more air it is recommended to change the needles from KD to KF if using a C cam, probably also with a D or K cam. Consider the change if you think the engine is running weak due to more air.
I suspect a few people will have kept these if they have done the change. Anyone got a spare? Clips are hard to find, but a couple of black tie wraps can look neat.

[Rustinmotion]

Originally Posted by JDW3696

Hi Derek,
Yeah I asked. Unfortunately they can't get the lid anymore so I was looking at alternatives. I'll keep looking.
Thanks
Joe

I used a box from a Tr7, you can get a NOS for little money, you need to be able to fill in the holes and reposition to fit the Volvo engine and it needs a spacer to pack out from the carbs otherwise you get the occasional interference with the steering column joint
Long term my plan was to replace the twin pipes with a 3” single and fit a cone filter, this would allow a set of ram pipes to be used inside the box

[arcturus]

Hi, I use the box on my B20b with the filter removed and the air pipe leading out to just behind the grill I have a filter at the end of the pipe. I noticed a difference from day one. Much peppier. (this on my 144)

[142 Guy]

I don't know about the Amazon; but, the later 140 did have the plastic airbox on the twin carb B20. The first year of the 140 was equipped with the B18 and the twin carb version of that engine had individual air filters as opposed to a common airbox.

The air box from the later B20B engine might be fit able. I believe the wrinkle may be that the B18 used the HS carburettor and by the time the B20 came along HIF or Stromberg carbs were fitted (at. I don't know whether the mounting flanges on the carbs are the same diameter and shape and whether the centerlines for the carbs are the same on the B18 and B20.

[Rustinmotion]

Originally Posted by 142 Guy

I don't know about the Amazon; but, the later 140 did have the plastic airbox on the twin carb B20. The first year of the 140 was equipped with the B18 and the twin carb version of that engine had individual air filters as opposed to a common airbox.

The air box from the later B20B engine might be fit able. I believe the wrinkle may be that the B18 used the HS carburettor and by the time the B20 came along HIF or Stromberg carbs were fitted (at. I don't know whether the mounting flanges on the carbs are the same diameter and shape and whether the centerlines for the carbs are the same on the B18 and B20.

Just cut the back out and fit an ally backing plate, I’m looking for one if anyone has one

[packers1712]

This is very similar to my set up, I'm not sure I can tell the difference between it and the K&N individual pancake filters that I bought the car with but I figured that if I can get air from the in front of the radiator to feed the carbs its got to be better!
(I guess the car in the picture is a Volvo 140 series?)

Doug.

[142 Guy]

Originally Posted by packers1712

This is very similar to my set up, I'm not sure I can tell the difference between it and the K&N individual pancake filters that I bought the car with but I figured that if I can get air from the in front of the radiator to feed the carbs its got to be better!
(I guess the car in the picture is a Volvo 140 series?)

Doug.

Better is relative.

Cooler air is denser so you potentially improve the peak horsepower potential if the carb tuning is set up to accommodate the cool air. The density effect is small since air density is a function of the temperature in absolute degrees. A drop of 20 C intake air temperature from +40C to +20C only gets you a (313 - 293)/313 - 6% increase in air density. The biggest benefit might be that if your car is detonation prone the reduced intake air temperature might reduce the tendency to detonate.

On the down side, the lower intake air temperature means that that you need to burn more fuel to achieve the same final combustion temperature so your fuel consumption will increase. Again, this effect tends to be small; but, becomes more significant in colder weather. Exhaust pre heat ovens became a thing after the 1973 energy crisis. They also improve cold weather driveability.

Everything is a compromise.