here's an idea for a diffuser...



similiar to the valyrie 370z rear
]

At max $200 in material

 

I would run the outer fin of the lower diffuser further in. You really want to isolate the turbulent flow from the rear tire/wheel away from the air passing under the car.

 

I just read through your entire thread. What a journey, there is a lot to be said for what you have done. What has most impressed me though was your willingness to experiment as you went. It takes a lot to venture out of your comfort zone.

In regards to your rear diffuser design.

At a minimum it needs to be in line with the inside of the tire. I cannot tell from his picture but it appears it needs an increased rake. if its parallel to the ground its only going to exacerbate the turbulent flow coming out from under the car and possibly cause a lifting force on the back end.

 

I planned the diffuser to be very simple. Just two vertical sections to protect the diffuser from nasty air. And one slightly raked horizontal piece spanning the two of them. The exhaust as you see it is being sold. A custom one is being made. We might tuck the exit up a bit higher in order to facilliate making the horizontal section. And it won't have a canister on it so it won't take up so much room.

 

Forgive the paint...you it looked like the outer lateral edge was about where the yellow is, but at worst you need to have it closer to the red line and run it as far back to the toe arm/spring bucket as you can to keep that crappy air out...

 

Yeah red line, and I think I will only be allowed to take it to the center of the rear axle for different rules. Then a big horizontal piece joining them. The exhaust will be up out of the way, almost like a center exit?

 

I do like the winglets on the 370 though that are behind the rear wheel.

 

The winglets are fine, so long as they are isolated from the flow under the car...

 

I'm either going to turn down the exhaust into diffuser or center exit it...

 

FWIW, the angle you depicted in the paint drawing is going to be too steep unless you are extending the diffuser a foot behind the bumper. You are going to get all kinds of separation at that angle without a seriously tunneled or skirted car.

 

Sub'd. Cool thread in and out. I am also planning on building a diffuser before next season. Interested to see what you come up with.

 

Double check guys, I posted that doodle just to get conversation going...

 

Hey Mike, We're all know you will be upgrade to the BRZ coilover. I just wonder what made you decided to keep running the OEM setup instead of true coilover setup? Wouldn't the OEM rear spring buckets setup limit the adjustability of the suspension geometry?

 

Well the JRZ will be a true coil over set up finally.

Previous to that in 2012 and 2013 I used off the shelf koni yellows and swift spec r springs.

2014 I used Nismo T2 springs and custom valved TC Kline Koni Yellows.

This was just a bang for the buck mod. I set a max budget for each year ( and usually run over).

 

How much time would you think you can shave off with the JRZ setup vs the old setup?

 

I'm not sure. It completely depends on track conditions, and length.

I'll post up some comparisons when I get a chance

 

Keep them posted when you have the chance, Mike. Same with the race video you posted on your YouTube channel. I never get bored watching them. Especially the one when you were chasing the GT-R35 and got pass by FD3s RX7 came out of nowhere.

 

Thanks I am going to be making a lot of improvements to my youtube channel this year. better videos. better sound. more in depth stuff.

 

so 6kg/mm true coil over converts to what in the oem location? is there a formula out there?

 

Right about 13k mounted in the bucket. I would have dig up motion ratio's. Once you have OEM motion ratio for OEM and true you can crunch numbers and compare