Bigger air intake ?

I saw in another thread that Pesky was going to do some mods that I have been thinking about: opening the rear grilles so they work as intended, (do I really have to take the rear clam off? I have a small working space)But I also wanted to make a more radical one: to make the airbox tubing attach directly to the left intake. The difference here is that I want a bigger left intake, in order to preserve the flow area of the tube. Then I would need to open more the fiberglass and make a replacement “scoop” (original is small) probably covered with some grille. Then I would have to do the same over the other side to improve engine cooling.Has anybody done this before?Rgds,Uldis

UldisThere was a thread about this recently - possibly by Mike Turner or Steve Green. I think that the conclusion was that it would also be sensible to fit some wire mesh in the intake in the body - to prevent grit etc getting into the airbox & beyond!

UldisCheck ou this gallery The most important mod was the number plate - the engine breathes so much better.The mini grilles below are very easy - all my chap did was remove the small grills, drill a 3" hole with large drill bit and replace the grill. Alternatively, you could cut the whole section out with a jig saw - no need to remove the clam.Mike

Took a look at all the postings regarding this issue, but only a few times the bigger intakes is mentioned.Basically it would involve having a larger opening in the sides (so maybe like 1 cm trimming on the inside edges of the scoop) and the scoop itself would be removed and another bigger one (always respecting the 6" OD) made.I have done this in the past with bikes, and I would need to find some black PVC to cut & bend.Advantages would be much better breathing and on the right the bigger intake would compensate for the blocked one.That, combined with opening the rear grilles should make it vent easier.And about the grilles, I would prefer to cut it all behind the lights mounts. You really think I don’t need to remove the clam for this? where should I stick my arm+saw to cut it?Rgds,Uldis

where should I stick my arm+saw to cut it?You may want to be careful how you post your questions, DudE!!

Hey, where’s my car ? [image][/image]

Hi Uldis,I’ve thought about opening up the air intake, but I remember Nick Adams talking about this. He said something about high speed airflow through a small vent which opens into a larger pipe means that the flow speed drops, and the pressure rises. This is what you need for good induction.Basically, you can get enough flow through that vent for a standard car. With a lot more power, you would need a bigger opening. Maybe Mr Admin would want to consider this on his supercharged beastie.

The side vent moulded-in vanes reduce the area by a significant ammount. What about replacing them with fine,open mesh (like the GT1) and an additional forward facing scoop attached to the bodywork. That could increase the airflow by a major factor. It would, however, increase drag to some degree at speeds approaching maximum.

Hmm, interesting point about pressures and velocities.Everything true, but looked at from a simple point of view. In any system where gas is moving (air) the pressure at the intake (outside of the car) would be more than the one on the other side (inside the hose connecting to the airbox), otherwise air wouldn’t move.The scoop is actually behaving like a choke and the tighter the choke, the more energy is lost at the exit side. So, just by putting in a choke, it would not “create” any extra pressure in the air hose. Pressure will simply increase from what it was in the middle of the scoop, but will not reach the original pressure outside.My thinking was to de-restrict as much as possible the intake (maybe it’s like that for noise pourposes).This triggered from what I felt on my first track day with the Exige. Somehow I felt it was running out of air at 7200 rpm, the engine noise was different, not like it was falling off the torque curve). Also, if you look at the exhaust it shows traces a little “rich” (without having any instrumentation I have to resort to reading the pipe)On Rob’s comment, if you look at the scoop from the front, theres like 2cm from the edge of the car to where the scoop actually starts (and then there’s like 2 more cm’s wasted on the black scoop itself). My idea would be to open it almost to the edge, this way you would have the effect of having added an external scoop without actually adding one. And on my impression the vane’s area would be the same as that of the grille’s area. But hey, if I make a new scoop, I would have to put grille anyway to avoid small birds from entering the engine !It’d be interesting to see the effects of all this in a stock engine.Next is, where do I find PVC so I can start molding out my first experiment?Uldis

I’m not trying to talk you out of this, or tell you you’re wrong.I’m no expert. But as I see it, opening the intake will only icrease the pressure inside if you’re approaching the maximum flow for that opening. The amount of air required is almost directly related to the power of the engine. If you look at the air intake on an F1 car, it’s not exactly huge, yet it supplies enough air to generate 800+ hp.Having said all that, I’d probably try it myself if I was brave enough [image][/image]

Good point, the current opening should be enough for I’ll take it easy. I’ll connect it sealed to the existing scoop and see what happens (mine is dangling now). But I’ll still have to source a pipe from B&Q, since the correct adaptor I ordered from Lotus (>1 month ago) hasn’t arrived. Meanwhile I’ll properly design and build a big one [image][/image]Cheers,Uldis

Dont forget if your force air direct into the airbox that you could mess up the mixture.My mini had front facing carbs and when it was on a rolling road you couldnt put the fan on otherwise the mixture when crazy.The solution was a big airbox and scoop - no air filter mind you - but I know the Miglia boys play around with baffles in the airbox so they get loads of cold STILL air.