[Chrisrw]

So I was building two small splitters to add to my OEM area lip.



I have now changed that and am looking at getting one large spoiler which would be custom made as well...

With that being said, I don't know too much about splitters. I know how it causes down force from stagnated air, but my lip has a lifted spot in the middle. From what I gather it's called a "venturi". "In essence, the front spoiler region of the car forms a "mini ground-effect tunnel". In the "throat" region of the venturi, the air flow speeds up and hence the local pressure goes down." This causes downforce.

I can only assume this last paragraph is correct.. if it is not please tell me!

PICTURES OF MY LIP: Notice the raised center "venturi".



So the "venturi" goes back a bit at a downward slope and by the time it reaches the bottom back of the lip, it's flat. where it bolts up to the bottom of the car, it is flat and there is NO "mini ground-effect tunnel".

The lip I will get will go back across my front axel like this one:


So from what I understand if I fit a splitter like the one above under my "venturi", that will cause a lot of stagnated air and give me a lot of downforce without having a super long splitter, I was going to go about 1.5-2'' forward from the lip. OR should I make a slot in the splitter to allow the "venturi" air to continue under the car. If I am correct, this will give me downforce as well due to the speed of the air...


ANYONE KNOW ANYTHING THAT CAN HELP ME??

PS, I know some of the info on the OEM lip is redundant, but I posted this on a few forums to get some help. Thanks in advance to everyone who knows more than me and is willing to help. I appreciate your time.

[J Tyler]

-The whole area/region above the splitter should be sealed. I.e., no "venturi" gap like you are thinking of. Even the holes for brakes/radiators/etc should theoretically be sealed. On racecars, the frontal areas of those holes are minimized. Holes/gaps above the splitter take away downforce and increase drag.

-Splitter should be flat & continuous across the entire lower surface of the front bumper.

-Splitter should extend backwards (towards the rear of the car) underneath the bumper/engine/etc as far as possible. Generally the further back you extend it, the less drag you will have.

$.02

[Hit_Apex]

Keep in mind the typical club racer splitter creates north of 150lbs of downforce at speed and will need to be secured to the frame and/or bumper beam. You should be able to stand on it.

[Chrisrw]

Ok, I was going to get one made that kooks up to the bottom bumper mounting points.. Is that bad or will that be ok?

And if the center gab above the splitter that would normally be the "venturi" gap was sealed.. is that good or would that pocket of air be bad?

[jbass524]

I completely support DIY and think you're great for trying. It just seems there is too much you don't know to venture into this if you want to be sure of getting something good. Maybe you just want to give it a shot no matter the outcome?

Why wouldn't you buy something that is already made by Vorsteiner or whoever else makes splitters for our cars?

Good luck no matter what direction you take.

[Chrisrw]

I wouldn't actually build it myself. I have a company willing to build it but they have never made one for an OEM lip before so I need to get a design for them... And I would buy one that someone already makes, but I want a fully functional one (the ones from most companies are more for looks).

[jbass524]

Originally Posted by Chrisrw

I wouldn't actually build it myself. I have a company willing to build it but they have never made one for an OEM lip before so I need to get a design for them... And I would buy one that someone already makes, but I want a fully functional one (the ones from most companies are more for looks).

Great reasons to build your own. I know Jeff Tyler drives the HP Autowerks car. They have a splitter and I'm sure they wouldn't put anything on that car that wasn't functional.

Jeff or Harold? What brand of splitter are you using?

[zsapphire7]

yea venturi effect is when air flows by a surface really fast creating low pressure and thus a "sucking" action. what you want is to make the underbody of the car completely flat and drag free so air can flow really fast under the car creating downforce by lowering pressure. By extending the front of the bumper with a "splitter" you split the high pressure air above the splitter that hits your car and the low pressure air that flies underneath the car to create the downforce. J Tyler is right, u want to cover as much of the underbody as possible but becareful about blocking the cooling vents for the transmission/differential. BLocking off any other holes above would make it more efficient too.

Lemme know what you decide to mount it to and how. I was thinkign bout custom fabing up some since i have fiberglass and some CF sheets lying around.. just havnt had time to play around with em yet.

[J Tyler]

Originally Posted by Hit_Apex

Keep in mind the typical club racer splitter creates north of 150lbs of downforce at speed and will need to be secured to the frame and/or bumper beam. You should be able to stand on it.

+1

Originally Posted by Chrisrw

Ok, I was going to get one made that kooks up to the bottom bumper mounting points.. Is that bad or will that be ok?

And if the center gab above the splitter that would normally be the "venturi" gap was sealed.. is that good or would that pocket of air be bad?

It should be secured like Hit_Apex said. The bumper can support downforce from a very small splitter, but anything highly functional for track purposes should be at least 3.5" long and that will likely create too much downforce for the bumper to hold at 120+mph.

Your "venturi" gap should be sealed, as should (ideally anyway) all surface area above the splitter. If you had a front splitter, all the "venturi" gap would do is take away downforce and add drag.

Look at NASCAR.... at some tracks they tape up almost the entire front grille for their qualifying lap. (The motor usually overheats & blows up after 1 or 2 laps, but the car makes more downforce & less drag!)

Originally Posted by jbass524

Great reasons to build your own. I know Jeff Tyler drives the HP Autowerks car. They have a splitter and I'm sure they wouldn't put anything on that car that wasn't functional.

Jeff or Harold? What brand of splitter are you using?

It's an APR. It's about 3.5" long, very functional:






OP, if I were you, I'd stick to something like what the HPAW car has: a simple, flat, sealed splitter that extends aft about 24". Anything more aggressive than that, or anything that extends further rearward than that, and you might start to create cooling issues and/or gas mileage issues. Good luck! I'm sure we'd all like to see how it turns out!