Scoop on Roadster

[PorkPie]

Robin Dripps asked how he can fix his problem with his scoop on his high boy roadster.

[PorkPie]

Sorry the system filed before I could wrote my comment and attached my picture:

I have to split the answer, due to this that the system allowed me not more attachment than the three:

Here the answer:

Solution one, would be a shorter scoop, behind the turbulence airflow.

Solution two, would be the scoop in front, inside the grill, this is normally allowed - question is - can Robin use a so solution.

[jimmy six]

To the best of my recollection I have never saw an air intake in the grille shell of a street roadster because it violates one of the rules mentioned in the second paragraph on page 50.

Many do not use the radiator for cooling so some creative work could be done but the rule may not be violated with out possibly being found illegal.

Most take air thru the radiator on on a flatter scoop mounted on the hood. Good luck

[PorkPie]

Next pack of the comment and picture.

Solution three, long scoop which is infront of the critical airflow.

What cause the problem:

The airflow picture shows you the critical airflow area in front and above the grill. Especially on the highest of the grill the airflow creates a lot of turbulences and airflow lift.

Inside this area is no clean airflow possible. There is no chance to get proper air inside a scoop.

The solution had to be:

In front of the grill, which can be - so as shown - through the grill or above the grill.
Through the grill would be the better solution, the cross section would be smaller.

Above the hood there are two solutions . in front - outside of the critical airflow, which would be more weight - or behind the critical airflow area - see picture short scoop.

A other problem is the scoop himself.

A scoop got in the intake a opening with a smaller cross section than the scoop cross section behind.

The original, shown scoop, got the problem that the volume behind the opening is not expand - in other words - there is no increase of the cross section.
The result - the pressure inside the scoop pressed the air backwards out of the scoop against the incoming air - first, a very bad turbulence inside the scoop, second no clean airflow to the carburator.
Third, no constant airpressure inside the scoop. Fourth, the backwards going air, which try to escape out of the scoop, disturb the airflow in front and around the scoop, which not helps to get a clean airflow inside the scoop.

By the way, Jimmy done there a comment - sorry, I didn't saw that Robin's roadster is in the street class - Jim could be right, that in this class a scoop in the grill wouldn't be allowed, but in the street roadster class the scoop can be above/in front of the grill.

Thanks Jim for your input.

Buy the way, I hope that the explanation of a right scoop is also for other roadster racer interested

If my comments are not unterstandable, let me know and I extend the information.

[robin dripps]

Pork Pie,
Thank you so much for all the time and effort you put into my question.  This is very helpful.  As has been pointed out, the street roadster class requires that the radiotor fills the grill shell, so it seems that a hood scoop is the only solution. I would worry about the extended scoop having so much leverage that it might lift the hood and therefore prefer the shorter version.  It is ironic that the short version of the scoop you show is close to the shape of the original scoop before we extended it thinking that in its original location the airflow would go over top the scoop. Oh well.  It also looks like the scoop itself is not the best configuration and we should look for one or build one that incrreases the section as it extends back.  We will be looking at these options over the winter.
Robin

[PorkPie]

Robin,

I would also prefer the short one - the long one is not only heavier, it could be also, if the hood is strong enough, a lifter - which makes the front suspension lighter - means, you are loosing downforce and makes the front wheels unstable.

[robin dripps]

Pork Pie,
I forgot to mention the other solution that has been raised and that is to get rid of the scoop altogether and just use the air that comes through the radiator hoping that the lower cd would make up for the warmer air and the potential loss of positive pressure to the injector stacks.
Robin

[PorkPie]

Robin,

I know that your grill is a standard open grill - did you have a chance to make a scoop behind the grill - inside, under the hood - don't know how high your engine build - alright, no scoop allowed through the grill - but some inches behind - is this possible. I'm not so in rules for roadster - we are running a streamliner, so may be someone of our inspectors on landracing.com can give here the right answer.

If the rules allowed a so solution and the engine got enough space, why not