What would you base a custom racecar off?

[mcbeth059]

I had a hard time coming up with the proper way to phrase that title; but lets say you're building a custom tube chassis racecar one the "cheap". Front engine, rear-drive.
Would it be smarter to base the build off a preexisting chassis like a Miata; use the hubs, brakes and differential. Or is it something to source individually, I.E hubs from an STI and a diff from some Z car. Or really any combination of any popular rear drive cars.

I'm just playing in my head and am curious to what other peoples opinions are.

[shanehutton]

It really depends on a couple of things:
1. Power goals (Can the parts handle the goal? Are they way overbuilt and expensive for the target?)
2. Availability (Can you get a part at a random parts store on a race weekend?)
3. Price
4. Compatibility

If you have modest power goals, the Miata is a great start. Light, available LSD, cheap, good aftermarket and local parts sources. Common bolt pattern for wheels. Donor car likely to have been a summer car etc. Lots of people have done it so the knowledge base is great.

[kmorris]

As a current built-from-scratch car owner, I have a little insight on this (mainly on how not to do it).

First you need to really think about what you want the car to do:

Do you want to drive it on the street, ever?

Do you want to carry a passenger?

If it's competition-only, what are the rules for that series - what's allowed or not?

Are there other series you might want to compete in with the car?

How fast do you really want to go?

And of course, realistically, what is your budget and what are your skills (now and as the project goes along) in the areas of design and fabrication, and how much time are you willing to spend on it (hours per week plus overall length of project)?

A few rules of thumb:

1. The closer your starting point is to your target, the less your project will cost overall, since every part of that transformation is going to cost you money and time.

2. The more people there are that have gone the route you are going, the more resources you will have available in terms of ready-made parts and people to ask for advice.

3. Advance planning will always save you time and effort in the end.

[mcbeth059]

Originally Posted by shanehutton

It really depends on a couple of things:
1. Power goals (Can the parts handle the goal? Are they way overbuilt and expensive for the target?)
2. Availability (Can you get a part at a random parts store on a race weekend?)
3. Price
4. Compatibility

If you have modest power goals, the Miata is a great start. Light, available LSD, cheap, good aftermarket and local parts sources. Common bolt pattern for wheels. Donor car likely to have been a summer car etc. Lots of people have done it so the knowledge base is great.

I'm actually playing with the idea of dropping a body on a chassis (think Roadkill's Nascarlo; if you haven't seen it the short version is that they drop a Monte Carlo body onto a oval track stock car chassis). Although I'm looking at a smaller scale of a FB RX7.

This is all just brainstorming, as I have some ideas in mind I'm just not sure if it's achievable. LS motor, custom suspension, lots of aero etc etc etc.

Originally Posted by kmorris

As a current built-from-scratch car owner, I have a little insight on this (mainly on how not to do it).

First you need to really think about what you want the car to do:

Do you want to drive it on the street, ever?

Do you want to carry a passenger?

If it's competition-only, what are the rules for that series - what's allowed or not?

Are there other series you might want to compete in with the car?

How fast do you really want to go?

And of course, realistically, what is your budget and what are your skills (now and as the project goes along) in the areas of design and fabrication, and how much time are you willing to spend on it (hours per week plus overall length of project)?

A few rules of thumb:

1. The closer your starting point is to your target, the less your project will cost overall, since every part of that transformation is going to cost you money and time.

2. The more people there are that have gone the route you are going, the more resources you will have available in terms of ready-made parts and people to ask for advice.

3. Advance planning will always save you time and effort in the end.

I'd like it to be streetable but it's home would be the race track. And you can see above kind of what I have "planned" so it would have a passenger.

I'm creative and relatively competent fabricator, and I'd probably give myself a 3-5 year plan for it to keep it relaxed and make sure it stays fun.

[Silex326]

If it's going to be under 2k lbs wet ( fuel , oil , coolant .. you ) then i would advise against an LS Engine as with that kind of power on tap and weight ( or lack there of ) the car is going to be twitchy or just over powered and essentially nearly undrivable .

Case in point i have a few friends with some older Chevette's weighing under 2100 lbs and they are all either running 350's or an LS engine and all are very nose heavy and nearly useless to drive beyond 50% throttle. as the 8 cylinders easily over power the 16" & 17" wheels

I am in the process of doing an engine swap on my Chevette ( just using it as a reference given it's wieght and intended purpose ) and i have choosen to go with the 3.6L V6 LFX engine & transmission from the 2014 + Camaro and here's why . It's lighter than the Shov-it's stock cast iron 1.6L boat anchor , makes 320bhp out of the box and makes plenty more power with minor bolt ons and a tune . Handling mods will be retro fit one offs .

in the case of a prebuilt chassis like a Miata or a BRZ/FRS i would take the most economial route that suits the intended purpose , parts availability .

both cars handle quite well on the tracks , both could use a little more help in the power delivery department . The 1.8L BP can acutally make some decent Jam with some boost ( I have friends in the Escort/Protege world pushing 550-600whp on 1.8L BP engines , one of them is on stock n/a interals ) in the case of the BRZ/FRS ... i'd go with a 6 cyl swap . EZ30(r) or EZ36 . ( dont use a light weight flywheel with an H6 )

I just threw out some idea's but again like the others said ... it comes down to end power goals , intended purpose .

[mcbeth059]

Originally Posted by Silex326

If it's going to be under 2k lbs wet ( fuel , oil , coolant .. you ) then i would advise against an LS Engine as with that kind of power on tap and weight ( or lack there of ) the car is going to be twitchy or just over powered and essentially nearly undrivable .

Case in point i have a few friends with some older Chevette's weighing under 2100 lbs and they are all either running 350's or an LS engine and all are very nose heavy and nearly useless to drive beyond 50% throttle. as the 8 cylinders easily over power the 16" & 17" wheels

I am in the process of doing an engine swap on my Chevette ( just using it as a reference given it's wieght and intended purpose ) and i have choosen to go with the 3.6L V6 LFX engine & transmission from the 2014 + Camaro and here's why . It's lighter than the Shov-it's stock cast iron 1.6L boat anchor , makes 320bhp out of the box and makes plenty more power with minor bolt ons and a tune . Handling mods will be retro fit one offs .

in the case of a prebuilt chassis like a Miata or a BRZ/FRS i would take the most economial route that suits the intended purpose , parts availability .

both cars handle quite well on the tracks , both could use a little more help in the power delivery department . The 1.8L BP can acutally make some decent Jam with some boost ( I have friends in the Escort/Protege world pushing 550-600whp on 1.8L BP engines , one of them is on stock n/a interals ) in the case of the BRZ/FRS ... i'd go with a 6 cyl swap . EZ30(r) or EZ36 . ( dont use a light weight flywheel with an H6 )

I just threw out some idea's but again like the others said ... it comes down to end power goals , intended purpose .

I disagree with the too much power for the weight. There are far too many examples that prove otherwise. Not to mention getting it under 2500lbs would be a feat, something around 350whp in a 2500lb chassis isn't something that's unheard of. Also with what I have in mind I would be able to run an extremely wide tire that would be more than capable of keeping it more planted.

BRZ's are still far to new to use for parts, even a written off one man still sell for over $5k. While wrecked Miata's can be found for much less.

Also parts for H6's are far to expensive and difficult to find in comparison to LS parts. Also I'd be able to mount an LS further back and have more manuverablilty over the H6, not to mention the power difference and practicality.

[iamthewheelman]

I may be biased but I would just build a tube frame S2000.

Buy a wrecked S2000 and take all the hubs, spindles, diff, motor, trans etc, etc. and then build a similarly sized tube frame chassis to bolt everything onto. In fact just copy the wheel base and track width.

S2000's have been known to go sub 1:20 at TMP with very slight modifications and street tires, and they are not exactly light. Imagine dropping 1000lbs from it and adding slicks?

Once you have the bugs worked out of the design, you could build a nice NA F20 with ITB's or swap in a K24 and make around 280whp and it would be very reliable and very balanced, as well as being cost effective to run.

I am just not a fan of dropping large motors and or throwing large horsepower at small wheel base cars that weren't designed for it. It never seems to work out as a complete package that is both fast and balanced to drive, along with being reliable.

If you are really wanting a V8 then I would just build something similar to a late model stock car and work in an independent rear suspension from a newer Mustang if you wanted to be unique.

So many possibilities!

[Slowpoke]

(If you fit. Which should be no problem if you're doing tube-frame.)

[xyz999]

Originally Posted by Slowpoke

(If you fit. Which should be no problem if you're doing tube-frame.)

Man I miss my Miata. It drives like a rocket and sounds like a beast.

[kmorris]

Is this the kind of project you're looking at?

UNIQUE-Track Day/Race Car-Ready to drive!

Looks like some serious fun!

[Doug P]

If your taking the time to build a tube frame race car I would use race car parts, not street parts

[ONdriver]

Another choice to consider:
http://exomotive.com/