Best way to increase downforce?

goldNSX · 3 November 2005

I think this haven't asked before but it's interesting to me. What are the best ways to increase downforce of the NSX WITHOUT heavy spoil(er

)ing it? I think of the front underbody where the hot air of the radiator is flowing under the whole car. As hot air has more pressure it lifts the car.

No just joking.

Seriously:
What about getting a wented hood so the hot air of the radiator flows over the car and then closing the front underbody and duct some air to the brakes which should produce more downforce and cool down the brakes? This should be an interesting CF project, a combo of hood/underbody. Does the wented hood provide enough cooling capacities or do I run into serious problems?

Thanks,
Thomas

spyderplayer2002 · 4 November 2005

I'm pretty sure the Procar wing gives more downforce also. The underbody trays wouldn't hurt either.

ncdogdoc · 4 November 2005

A vented hood increases cooling capabilities, but to increase downforce you would need to create a duct from the bumper opening to the vent (including the radiator/fan). Otherwise the vent just decreases lift (not a bad side effect at very high speeds). The vent does direct hot air right over the HVAC inlet in front of the passenger windshield area, slightly increasing the cabin temperature.

A splitter with an undertray will also help.

Lastly, I am toying with the idea of vented fenders, ala C6R and the Maserati ALMS cars.

titaniumdave · 8 November 2005

I have a vented hood, Dali Banana boat special and I have been running a RM front splitter. Here are my thoughts:

I was pretty unhappy with the way my car would start to feel light in the front end at speeds over 120 MPH, and not much fun at all when I went over 135 MPH, a basic 'pucker fest' at 155 MPH(the fastest I have gone!). This was with the stock hood, stock air dam and Eibach lowering springs. The basic problem seems to be air flow, as pressure builds with higher speed air gets trapped under the car, or more accurately, the pressure differential between the top and bottom of the car does not change as quickly in the front as in the rear. I decided there were 3 ways to help this situation, 1. Prevent some of the air from going under the car(splitter), 2. Help draw the air that is getting forced through the radiator and under the car out(hood vent), 3. Draw the air out from the back of the car with reduced pressure(rear diffuser). The first 2 seemed like the places I could make the most difference with the least expense and no permanent changes to the car.

I did both the hood and the splitter at the same time and was amazed at the difference it made in the way the car feels at speed. Loved it all and it seemed like both together were what made all the difference! Fast forward 6 months and I am tracking at Spokane raceway http://www.spokaneracewaypark.com/ which has a 3/4 mile long front straight, 145 MPH plus with out trying. Car is great, I am having fun. I offer to let my friend take a couple of laps in the car and he has a minor 2 wheel off, of course it it the one corner with a 4" deep rut on the edge of the track! There goes the splitter! We roll back into the pits and unbolt the shattered bits that are left on the car. I head back out on the track and I swear the car feels no different with the splitter gone. It sure seems like I should have less grip on the front end, but the car is as glued to the road as when the splitter was there!

My conlusion has been to leave the whole splitter/air dam off, be able to drive in and out of driveways for the first time ever and enjoy the difference the vented hood makes. The hood does reach very far down into the area behind the radiator which I think does have an effect on how it 'pulls' air out and up. I can not stick a spare tire in the front compartment and I think this helps with air flow for cooling and reduced front end lift.

My next mod will be an under body tray to smooth out the air flow under the car, and a deflector to direct all of the air from the rdiator up and out of the hood vent.

ScienceofSpeed · 8 November 2005

I agree with Dave's post above. A vented hood makes a dramatic difference in high speed handling of the cars. Per Honda's NSX-R research, the most significant change in aerodynamics was achieved by reducing lift in the front of the car. We have a special now on the NSX-R style hood if you're interested:

http://www.nsxprime.com/forums/showthread.php?t=60045

Cheers,
-- Chris

john@johnhudakracing · 8 November 2005

http://www.tfd.chalmers.se/~lelo/rvad/reports/rva2002_gr02_underbody.pdf

Hrant · 8 November 2005

John@Microsoft said:
http://www.tfd.chalmers.se/~lelo/rvad/reports/rva2002_gr02_underbody.pdf

Excellent and easy to read for nontechies.

goldNSX · 9 November 2005

John@Microsoft said:
http://www.tfd.chalmers.se/~lelo/rvad/reports/rva2002_gr02_underbody.pdf

Thanks very much for the excellent link. Let's me think about my physics lessons at scool and about a new hood.

goldNSX · 9 November 2005

titaniumdave said:
I have a vented hood, Dali Banana boat special and I have been running a RM front splitter.

Thank you very much for your excellent input. Do you have a picture of the hood? I'd be interested.

Ponyboy · 9 November 2005

Hrant said:
Excellent and easy to read for nontechies.

Indeed! I printed it out for review at home. Good stuff.

NSXDreamer2 · 10 November 2005

Dali Banana boat special

Dave, what is that??

and Chris@sos, your vented hood is at a very good price and proved to be good quality. But it's without the scoop right? So how does it reduce lift without the scoop inside the front compartment??

ScienceofSpeed · 10 November 2005

NSXDreamer2 said:
Dave, what is that??

and Chris@sos, your vented hood is at a very good price and proved to be good quality. But it's without the scoop right? So how does it reduce lift without the scoop inside the front compartment??

The duct does extend into the bonnet area. You could also enshroud the radiator if you wanted the full effect.

Regards,
-- Chris

titaniumdave · 10 November 2005

Here is a pic of the hood and the splitter. There is quite a benefit from just having the scoop to provide a direction for air flow up instead of having to force the air either down under the car or out throught the wheel wells. The benefit can be increased by creating a smoother flow through the bonnet area, and directing all the air flow out throught the scoop.

TTony · 11 November 2005

:biggrin:

But seriously, Chris are there any hoods left?

goldNSX · 12 November 2005

titaniumdave said:
Here is a pic of the hood and the splitter. There is quite a benefit from just having the scoop to provide a direction for air flow up instead of having to force the air either down under the car or out throught the wheel wells. The benefit can be increased by creating a smoother flow through the bonnet area, and directing all the air flow out throught the scoop.

I've never seen this hood. A special-built one?

jrehner · 13 November 2005

I take offense at the crack about heavy spoilers. Mine has the vented hood and the incredibly heavy ADJUSTABLE spoiler on it. Nothin's gonna make my rear bounce in the air. (There's a visual) I'd show a pic if I could figure out how to post it here... LOL

titaniumdave · 14 November 2005

goldNSX said:
I've never seen this hood. A special-built one?

MJ at Dali had it fabricated in San Deigo, nice work and it is all aluminum built from a stock hood, very strong and a perfect fit. Scoop is as big as it can be and still clear the ABS.

Best way to increase downforce?

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