Stillen front splitter and rear diffuser

[kumar]

Is there any sort of consensus on whether these 2 parts will be beneficial at high speeds or not?

Looking at it from an amateur perspective, I would think they should obviously provide better downforce.

Having searched, I see many are worried about how they may effect the aerodynamic balance of the car and don't want to change the factory parts.

 

[kumar]

i see Kyle lurking

:huge:

 

[kmillen]

Yup, I'm here.

We have tested these parts up to around 160 MPH. We haven't had an oppurtunity to push our car any faster than that. We found that it definitely made the car more stable at those speeds and helped quite a bit with the handling and cornering while at higher speed.

For the guys looking at the 1 mile runs or speeds around 200 MPH. Unfortunately we don't have any experience with these parts on the Ford GT at those speeds. We do have a lot of racing experience with other cars at those speeds but not specifically the FGT.

 

[kumar]

Hmmm thanks for the honest answer. I will ask around to some non GT folk and try to come up with a decision. The Mile is one of the venues where I plan to run my car.

 

[kmillen]

I probably would not recommend running the front spoiler in a 1 mile event. I'm not an aerodynamics engineer but it would make sense to me that increased downforce would actually slow you down. Yes, it would make the car more stable but it would slow your ability to reach that speed in such a short distance.

If you were racing at Le Mans or Nurburgring where you are cornering at high speeds than the added downforce would be beneficial and help plant the car. However, in a straight line top speed run I would imagine that the added downforce would only slow you down a little bit.

I am not an expert by any means in regards to aerodynamics or 1 mile runs. All of the events that we participate in are at road course race tracks and that is where my experience lies. Steve has raced in everything from single seaters to IMSA prototype race cars, Mickey Thompson desert trucks, and rally cars. He knows how to make a car handle extremely well on a race course but I don't know if he's ever done a 1 mile event other than magazine tests such as the one he did for Road and Track when he drove one of the Hennessey Viper's.

 

[kmillen]

I just spoke with Steve and he agreed that for a 1 mile event the front splitter would slow you down a little bit because of the increased drag.

It will definitely help the aerodynamic stability but the whole point of doing a 1 mile run is to reach top speed as quickly as possible and the increased downforce created by the front splitter would probably hinder your top speed capability a little bit.

 

[kumar]

badass

what about the rear?

 

[kmillen]

Same thing really...Both of these parts are designed to increase the downforce on your car. I don't think increased downforce is what your after.

 

[kumar]

hmmm might go with the stock length rear then

my stock one is hurting from running into stuff all the time

 

[Indy GT]

Sufice it to say Fred's team of aerodynamic engineers did a lot of wind tunnel testing of the FGT shape. And the original GT-40 shape. There are compromises in every design to be sure. The engineers I have spoken to on the team framiliar with the aerodynamic load data Ford recorded during testing expressed aerodynamic concerns for using front chin spoiler and rear diffusers of different dimensions than the OEM units on our cars.

 

[TEXAS GT]

You don't need to change anything for stability on a GT for straight line performance. I've driven one 193 mph at The Mile that was completely stock except for engine mods and another one 203 mph that was stock except for turbos and lowered suspension. You could take your hands off the steering wheel anytime you wanted to with either car (but please don't). I don't believe you could make these cars any more stable than they are right out of the box. Even the lowered suspension didn't make any difference.

Don't waste your money or time trying to improve the aerodynamics, Ford got it right the first time.:thumbsup

 

[B O N Y]

Ass-o-lutely....
Changing the air dam. Wicker, defuser can lead to major balance issues....
Good advise!!!

 

[STORMCAT]

The function of the rear diffuser cleans up the air that comes from under the car. Diffusers channel the air cleanly and help remove turbulence thus helping the cars efficiency at higher speeds. A Diffuser does not perform as a full venturi section on the bottom of let's say a Formula 1 car. That being said the longer lower Stillen diffuser should help the efficiency thus reducing drag. It should not make the car unstable.

Adding length to the diffuser is not the same as adding length to the rear wicker spoiler or the front splitter that will change the balance for sure.

If my memory serves me correctly Roketman Ron is running a Stillen rear diffuser. He asked one of the SVT team members at Rally 3 about the larger diffuser. The SVT member replied that the factory rear diffuser could have been larger thus more efficiency but for clearance and Aesthetic reasons it was produced at the size we have.

Look at the diffusers on the Matech GT or The Corvette C6R . They are longer and lower which just gives you more channeling surface and control area which leads to better efficiency.

 

[kumar]

You don't need to change anything for stability on a GT for straight line performance. I've driven one 193 mph at The Mile that was completely stock except for engine mods and another one 203 mph that was stock except for turbos and lowered suspension. You could take your hands off the steering wheel anytime you wanted to with either car (but please don't). I don't believe you could make these cars any more stable than they are right out of the box. Even the lowered suspension didn't make any difference.

Don't waste your money or time trying to improve the aerodynamics, Ford got it right the first time.:thumbsup

are you running penskes or just the sleeves? if penske, would you say they are worth it if the car isnt going to be a track whore?

 

[FB GT40]

Penske

Penske, Penske, Penske - even for the road! A discernable difference - even if she's not a track whore - but an occasional track slut!!

 

[kumar]

Penske, Penske, Penske - even for the road! A discernable difference - even if she's not a track whore - but an occasional track slut!!

I need to track down a local member with the Penskes. It's one mod I have been going back on forth on for weeks.

I see the track maybe twice a year. But it would be nice to lower the car more than 0.75 inches and not worry if that is too low for the stock shocks. I noticed that KW is also making a set of coilovers for the GT now.

 

[roketman]

The Penske non adjustable I think are the way to go .I have spoken with Alex and Tom in length about them .Alex also has all the trick set up #s for alignment ,caster ,toe and camber.This in itself is priceless!!!A vast improvement for the street and the track.
As racer the last thing I would want do do is put adjustable shocks on a 90%street driving car .Although if you decide you do want adjustables the non adjustables can be made in to adjustables !!Thats the only kind of adjustment I care for !! You have to constantly check them and adjust to weather and driving conditions. On race weekends we would need atleast 1 day just to get a decent base set up.
Get the Penske t&a 's while they are still available .My 02.

 

[B O N Y]

thanks Ron,....
I have written it time and time again...
Support our sponsors, they give back so much.
When we need tech support they are always here for us...
Can you put a price tag on their advise and support, do you remember Tom and Alex busting butt in the hot sun at Rally III at the track event?
I sure as do!

 

[kumar]

The Penske non adjustable I think are the way to go .I have spoken with Alex and Tom in length about them .Alex also has all the trick set up #s for alignment ,caster ,toe and camber.This in itself is priceless!!!A vast improvement for the street and the track.
As racer the last thing I would want do do is put adjustable shocks on a 90%street driving car .Although if you decide you do want adjustables the non adjustables can be made in to adjustables !!Thats the only kind of adjustment I care for !! You have to constantly check them and adjust to weather and driving conditions. On race weekends we would need atleast 1 day just to get a decent base set up.
Get the Penske t&a 's while they are still available .My 02.

I was looking at the single adjustables. I am trying to do my research on suspension just to understand the basics before I dive in head first.

Correct me if I am wrong: on the single adjustables, Alex presets the rebound and compression settings? But I still have the option of firming up or softening the shocks depending on what I am going to be doing that day?

That sounds like something that would be better for me than having two or three separate adjustments for rebound and low/high speed compression and having to dial them in one by one. I don't really have the experience or knowledge for that.

Maybe I should just email Alex.

 

[B O N Y]

alex : aszilagyi@comcast.net


tom: reichrace@hotmail.com