Why did the Longtail have air restrictors?

I'm trying to understand the following from you Mclaren gurus.

1) Did the Le mans always have rules that air restrictors had to be used on all cars?

2) Why couldn't the air restrictors in the Mclaren Longtail be removed so the car could go faster?

3)Did faster cars also have restrictors?

4) How much extra power would the Longtail have had without the air restrictors?

5) How hard was it to remove them? what do they look like?

Thank you
Daniel

I'll try to answer some of the questions - others may be along to answer the others / correct my answers

1. No, in the early days it was a kind of 'free for all' and technology and knowledge was such that restrictors only really came into being in the latter parts of the 20th Century. IIRC restrictors are used for cars in the same class but have differing power outputs to try to make a level playing field ;)

2. I haven't heard of them being in the GT, so the GTR class rules would have prevented their removal

3. Faster cars have had restrictors to make them not as fast

4. GT had 627bhp, GTR had ~600bhp. If the GTR had the restrictors removed - :dunno:

5. They weren't too hard to remove, and looked like IIRC cylinders reducing the circumferance of the inlets to restrict the amount of air going in

As far as I am aware all of the GTR's be they short or long tails had air restrictors fitted to try and reign in their power. The road cars were not restricted, however due to the remapping and other modifications a de restricted GTR has an output greater than the roadcars, where I am less sure is the state of tune of the LM's but would guess them to be similar to a derestricted GTR.

And 1995 GTR had around 636bhp, 1996 had around 600bhp. (If I remember story right)
Source: Racecar engineering magazine

LM has I think 668bhp?

And 1995 GTR had around 636bhp, 1996 had around 600bhp. (If I remember story right)
Source: Racecar engineering magazine

LM has I think 668bhp?

LM's do have the same engines like the GTR's, but without air restrictor.
Their topspeed isn't faster than de 'standard' models, because of the HD kit.

Someone feel free to correct me if I'm wrong but I heard that the Longtail, although less horse power had faster track times over the conventional GTR due to improved aerodynamics. So even though it had restrictors and was de-stroked, it still compared well. I just cant help but wonder though how the Longtail could have panned out to the likes of Porsche down the stretches without the restrictors. Does anyone think the slight gain of power without the restrictors may have helped? My understanding was that Porsche was a bit faster down the straights.

Unfortunately with racing, restrictors are what the governing bodies feel is fair to equalize horsepower. Barring any mechanical failures, the rest is tuning, gearing, aerodynamics, and driver skill.

The Porsche GT1s weren't as dominant as they had hoped when the GTRs were unleashed in 1997.