Airdam with or without splitter?

[RebekahsZ]

I'm building an airdam first and foremost to stop air from entering the engine bay. Should I terminate the airdam in a splitter lip or without it?

[SPARKY]

One of the reasons you are keeping air out of the eng. bay is to minimize front end lift---a splitter will definitely help that cause  remember it can not stick out in front of the frt bumper

[RebekahsZ]

Here's a picture at the Ohio Mile in May 2015, ran 167 and wanna go faster at the June 2015 meet.

[RebekahsZ]

Here's an in-progress picture of the airdam I'm building.  I need to trim the belly pan that it is built upon-just don't know whether to trim it flush with the vertical portion or if I should leave a 3-inch splitter hanging out there.  Please offer any advice you can.

[SPARKY]

To be legal under SCTA rules you will have to back slope the air dam if you want to have any spliter that does not stick forward of the front bumper profile and not to extend past the front fender  that forms the front edge of the wheel well

[RebekahsZ]

Thanks Sparky. What class are you quoting?  I will be running at the ECTA, never on salt for this tin can, although El Mirage is not out of the question (dirt). I am building for the Modified Sports class, which seems to be pretty well open to modifications forward of the cowl. So I was thinking that airdam mods were unrestricted. In that class bumpers may be removed and streamlining is unrestricted as I read it (ECTA rule book, not SCTA). I think for now I would like to limit this thread to aerodynamics concepts rather than rule books. However, you are the only person offering advice so for that I am thankful.

[jacksoni]

FWIW, pretty much ECTA follows SCTA on these sort of rules. Indeed the dam as shown covers the grill so would be /MS or if a sedan /Alt in which case you can do what you want to the front of the car. Attached a photo of a /MS car I was involved with ( me on the right there) in 2010. Started as a Bugeye Sprite. Back still is. Front not so much 

[SPARKY]

I didn't pick up on the     /MS splitter will help with body lift---doesn't take much of a lip

[RebekahsZ]

One of the things in noticing is that most of the airdams I see in landspeed do not have a lower lip, the photo you show is such an example. Is that tradition or is the lip (splitter) disadvantageous from a drag perspective? 

[SPARKY]

don't have data facts, just a little experience, and a lot of reading

 my old lakester hunted bad until I redesigned the frt nose (went to a mild v nose put a 2" splitter on it just a little less that 2" off ground0  and got rid of the 3" of + scrub radius

[wheelrdealer]

With the old spoiler under the grill in front of the valence  the car hunted a little at Bonneville after mile 2, but not bad. At Maxton I noticed side pictures in the traps the front end looked higher than at rest so there must be some lift occurring. Attached is the new and untested air dam for a CGALT which cannot be in front of the tip of the bumper. I wanted to build a splitter but did not have to depth to make one I thought would work.

I got the idea, limited data and advice from a HOT Rod article by David Frieberger and Keith Turk did on their Camaro a few years back. I think it still  comes up on Hotrod.com.

Anyway, my 2 cents is make a separate bottom section to the air dam lip. If you enlarge my photo you will see the bottom 2" strip bolts on. I made a 3" and a 1" strip to adjust to different surfaces and tires. Maxton comes to mind. Also, it happens the lip might catch something on the return road, the trailer  or on the track. If you make a spare lip then its a quick swap. Also the rule of spares is in play...if you have a spare you probably wont need it!

Looks good and I like the splitter idea if its legal  for MS.

Bill

[WOODY@DDLLC]

You can guess but you really should test! 

http://www.hotrod.com/how-to/paint-body/113-0703-car-aerodynamics/

[jimmy six]

My memory isn't that good but I remember a Cadillac Modified Sports that flipped when he turned off after a 200+ pass. Very low Spitter/air dam caught on the lumpy rough undrug salt. Always good to find a turn off if you can....

[hotrod]

Always a bad idea to run over your airdam after the crunchies rip it off. Make it so the bottom edge fails gracefully if you hit some big crunchies. Heavy rubber belting for the bottom 2 inches is one way to give it a fail safe if you encounter rough salt.

Salt conditions vary year to year, some years the whole area is flat as a parking lot, other years off the area which has been prepped with the drags you and 2-3 inch tall crunchies sticking up.

[RebekahsZ]

Here's where I leave it for 24 hours while I'm out of town.  Hoping to get some glass applied this weekend.  So a splitter it is!  I appreciate all the input.  This will be an airdam for Wilmington Air Park only.  That means:  not too low due to the runway lights in the staging lanes.  It will need to come off to get on and off of the trailer.  Next week I hope to start building the internal structure required to keep it out from under my tires!  I bet one loses cool points for driving over his air dam.