Low HP Car Downforce

Hi, I'm currently building my project car a 1994 Toyota AE101 with 4age 20v. It produces around 160hp at the engine and probably 130 at the wheel. I was wondering how much gain is there with me investing hundreds of dollars in aerodynamic parts (rear spoiler, front splitter, flat bottom, rear splitter). Would there be any noticeable gain on track? If so which mod should I definitely go for?

Thank you!!

You need to decide what the balance of the car is as it runs now. That will help you narrow the options toward what would be the most helpful on track. If the car tends to understeer, look towards the front items (splitter, airdam). If the car tends more toward oversteer, then the option should be more rear biased (spoiler, wing, diffuser). A neutral car can benefit from all of the items, but each may push the car toward under/oversteer. A flat floor is not going to pay big results until you get the ride height pretty close to the ground and would work in combination with a splitter and diffuser.

On the concern of drag, any downforce gained will increase drag (Mostly!). You top speed will be impacted by drag increase as if it is a power reduction, but the cornering speeds will be increased and reduce overall lap time more than the top speed reduction hurts it.

You could look at simple drag reduction on the upper body to help recover some of the drag generated by the downforce creating items.

Your power levels are similar to an early Miata, and those cars have shown themselves to be quite responsive to aero improvements with a lot of online information on what's been tried and worked. Stafford1500 is the wizard at this stuff.

Splitters and airdams can be magical, improving cooling and downforce and decreasing drag all at the same time. They're also pretty easy to DIY. Then chuck an adjustable wing on the back (9Lives Racing makes ones that actually work and are reasonably priced) and you can do some crude balancing using the wing angle and the length of the splitter. On my car, I also added some dive planes for balance but they're pretty draggy so they may not be ideal for your use.

I'd be worried that a rear spoiler big enough to do much would be pretty draggy, but most of my experience is with wings so I am talking through my hat to some extent.

For those (like myself) who don't speak Toyota, here is an AE101.

When you say "track", what do you mean? A specific place? A certain type of competition?

In reply to Robbie (Forum Supporter) :

Its don't intend to do any competition with this car. It's more of an experiment track car kinda thing. I live in Thailand so most of the time track here you rarely reach any high speed, such as Bira Circuit, Thailand Circuit Nakornchaisri, Kaeng Kajarn Circuit. I usually do track days with my friends who race Toyota Vios OMR. 

In reply to stafford1500 :

Thankyou for your comment! I just recently installed a massive rear spoiler which helps mid-corner oversteer massively but it also reduces my top speed quite a bit. I'm currently running the lowest ride height possible on my Tein suspension. You were mentioning about flat floor not giving big result, how close does my car have to be to the ground to get any major effect and how aggressive should my front and rear splitter be? Also how would I reduce grad on the upper body?

Thanks!!

In reply to Keith Tanner :

I had just installed a massive rear wing (Voltex GT wing) and it really made a huge difference even at highway driving. Mid corner oversteer seems to be reduced by quite a lot however like you said my top speed is reduced quite a lot aswell (can feel it bogging at 160kph instead of 180kph). I was wondering how aggressive should I put these air dams and F/R splitters?

Thanks!!

I think a flat floor will help you reduce drag no matter the ride height, and that may be useful and worthwhile if top speed is an issue. 

In terms of front splitter, does it need one now? ie are you seeing understeer?

As said, it's all about balance. 

Drive the car as is and see how it responds. There is a lot of mechanical grip tuning you can do prior to diving into aero, which will all have to be done again after adding aero so you may as well get some practice, ha! 

Focus on consistency with your laps, and maximizing your car in its purest form before diving into the aero realm. Have fun, and do a little bit of testing at a time. 

My 2 cents.