Track car design I've been working on

Over the last year decided to teach myself fusion 360 to help with my interest in designing my own track car.  Car is designed around a ZF8hp paired with some sort of chevy ls style engine, likely a iron block LQ# which is why ive stretched the front to bring that weight towards the center and rearward of the front contact patch. This is mostly due to ease of finding these, cost, durability and banging through 8 gears is just so sweet. I tried to add elements of tunability to the car through principals learned in books by seward and smith, various adjustments like the spacers that allow wishbone attachment to vertically move +- 1 inch to adjust roll/instantaneous centers for example. The frame isnt currently validated with FEA  like the aero hasnt been validated with CFD, (aero like the infinity wing is currently for funsies and like everything is subject to change.) I like the idea of an 8-1 collecter with equal length stepped headers (steps not pictured) for the sound even tho theyre likely a little less efficient that a really good tri y or something. The bellcranks are currently at a 2:1 at 30 degree pushrods, currently 3 inches wheel travel. Heave spring for eventual aero development. Played around with a few body design ideas but i need to keep drawing and coming up with a body shape/ style i like

Track 78"

Wheelbase 100"

estimated weight, not sure. probably similar to something like an ultima so like 1000-1200 kg? 

The reason I want to build a car vs just buying a track ready car which would be easier simpler and far cheaper, is the challenge and enjoyment of making something from scratch. I have welding and machining/ fabricating pre reqs from previous jobs and people in my life that can assist me luckily. Slowly working away, hoping to start in 2/3 years (currently building a house) so ive got time to continue refining/ redesigning etc. The car isnt for any class or designed to meet any stats. It'll be a garage queen for the winter and hopefully do 8-12 track days/ time attacks a year if i can get out. 

Looking for some constructive criticism 

This is insanely awesome.

Please, please, PLEASE follow through.

If I could just make one suggestion (I know ... everyone's a critic, right?)

As long as you're starting from a clean-sheet, might as well design the cage to fit around modern full-containment seats. From the images, it doesn't look like there's enough clearance around the head/shoulders to fit one.

My gut feeling is that the exhaust is going to cook a lot of things, and clearance is going to be fun as the exhaust expands with heat.  I've seen stainless exhausts grow an inch in length over the length of a car, you're going to have to account for that.

On that note, while you're adapting to a weird transmission anyway, why not just adapt to an Audi transaxle and go mid engined.  You have to route coolant to the front but that generates less heat than routing exhaust to the rear.

I like short wheelbase vehicles but 100" seems short for the amount of speed this may be able to generate, dependent on what your intended tracks are.

In reply to LanEvo :

Thank you very much

The cockpit is probably bigger than it seems. The seat itself is 34 inches tall and 4.5 inches off the floor, its an random model i got of grab cad a long time ago as a place holder that i scaled up to be the same size as a seat like this The seats for the winners - P 1300 GT (recaro-automotive.com) I believe this is what you mean

Ive hummed and hawed multiple times over the height as well as the angles on how the roll cage sides affect the shoulder width, the windshield here is modeled off dimensions from a corvette forum of a c7, so im not entirely sure what windshield ill be using and theres room to move it around. Id like a proper glass windshield as it would be nice to potentially hold the door open for street legality over some sort of lexan with coatings or whatever is used... Im pretty large, 6'4 and 230 and i dont want to be miserable in this thing. I think as is it should be pretty roomy as far as race cars go. The model here is scaled here to 6'4 

My only suggestion would be a cage that meets FIA specification or stronger. Not whatever this homegrown design is. 

Are you using known running gear? Its one thing to draw something up in cad, but if you want to be able to build it you should make sure you are modeling specific parts.

z31maniac said:

My only suggestion would be a cage that meets FIA specification or stronger. Not whatever this homegrown design is. 

Along those lines be sure to figure out exactly what you want to do with the car and make sure that's possible. A lot of track day and TT organizations aren't super friendly to non-production car based vehicles, and the few that are will probably have some fairly specific safety requirements. It'd be a real shame to go to all this effort and expense just to find you can't actually do anything with the car.

Really cool design and rendering but the frame's a mess. Lots of unreinforced bends (tubes only like loads along their axes - if they're bent compressive loads like to bend them further) and long/thin rectangles that'll parallelogram easily without putting much load on the tubes. 

I'll give a +1 to ensuring it meets cage & seat requirements for what you want to do, other than that the only thing that jumps out at me is the wheels looking pretty small, what size are those? The best selection of tires is now in 19s and 18s so that's the diameter you should aim for, and with this much power and downforce you should be looking at 11"+ wide wheels with a square setup for ease of maintenance/rotations.

smichers said:

In reply to LanEvo :

Thank you very much

 

The cockpit is probably bigger than it seems. The seat itself is 34 inches tall and 4.5 inches off the floor, its an random model i got of grab cad a long time ago as a place holder that i scaled up to be the same size as a seat like this The seats for the winners - P 1300 GT (recaro-automotive.com) I believe this is what you mean

 

Ive hummed and hawed multiple times over the height as well as the angles on how the roll cage sides affect the shoulder width, the windshield here is modeled off dimensions from a corvette forum of a c7, so im not entirely sure what windshield ill be using and theres room to move it around. Id like a proper glass windshield as it would be nice to potentially hold the door open for street legality over some sort of lexan with coatings or whatever is used... Im pretty large, 6'4 and 230 and i dont want to be miserable in this thing. I think as is it should be pretty roomy as far as race cars go. The model here is scaled here to 6'4 

 

That's not passing the broomstick test, you'll need to sit lower or raise the cage.

Even if the cage didn't look like it was intended to bend easily - and that one does, with all the tubes that connect unsupported to the middle of other tubes instead of meeting at common joints - if you are in a situation where you need a cage, the cage WILL deform.  And seat belts are amazingly elastic no matter how tight you wear them.

I second the fact that you need to base the cage exactly on your desired organizations cage specs.  They won't let something far afield on track.   FIA is probably an excellent fall back/catchall.  

For track width do you actually mean a 78" track width or do you mean a OA axle width of 78".  A 78" track width would be like 90+" wide with a 12+" tire.  

My LMP360 is 73" overall which is the same (+/- 1") as a actual LMP car.  I could see your aero getting out around the 85-90" range but that is a WIDE car.  

Don't be surprised if your weight ends up substantially above 1000kg.  Your not making a small car and unless substantial parts of it are Carbon it's just really hard to wind up <2500lbs.  Which is absolutely fine, imagine a Z06 -700lbs.  It's going to be crazy.  

The concept looks great, do some structural refinement, ask lots of questions and keep after it.