Momentary Turbo Boost / Rear Mounted Radiator Blower?
 

Hello!
I'm working on an ultralight Miata Kart and I'm aiming for 1,000 pounds curb weight. I've started thinking about Turbos. If I had a Turbo I'd want it to work like I thought Turbos worked when I was a kid - I'd want a trigger on the shifter where I can activate bursts of Turbo. You know, Turbo Boost.

So, I'm wondering if I could have a rear mounted radiator tucked in the back, and then use a Turbo to provide it with pressurized air. When I want the turbo boost, I'd close off the radiator air supply and then, boom, Turbo!!!

I know this is silly but, does anybody think this is a good idea, or that it would work like I'm imagining?

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It might work, not sure how healthy it'd be for the turbo, you may end up spinning it too fast too often, as it tries to maintain boost levels with a giant leak. No need to duct it to the radiator, put the rad in the trunk if you must and duct it properly. Use the switch on shifter to either trigger nitrous, or an ebc that increases boost significantly. This is sometimes called a "scramble" button, and the inner 13 year old in me always appreciated the name.

Bad idea, just come up with a front mount air to air like everyone else.
Radiators do NOT have the "turbulators" that a true intercooler has and although they are fine for removing heat from a liquid they suck at removing heat from a gas.
Huge volume of tubes to fill as well, will make "turbo lag" like nothing else.
Switching the turbo on and off with an electric switch is a pipe dream.
Mad Max was complete BS. That electronic clutch on the front of that blower was for movie audiences ONLY.
The real car was not blown at all...

ITBs are a no-no on a boosted vehicle. You CAN make them work but they will not add ANY power and increase the complexity hugely.
IMO just build the "cart" NA initially.
120 hp with 1K weight will be badassed...

ITBs are far more useful on a NA motor but...
The "proper" set up is a maximum effort high compression, monster cams motor built for high RPM.
They will not add power to a stock motor and they MIGHT decrease midrange torque.

Thanks for the replies!

I didn't make it clear - the rear mounted radiator would be cooling the car. The turbo would just be a source of high pressure air for the radiator. Then, when the air supply to the radiator is cut off, the turbo would pressurize the manifold.

I'm thinking that non-intercooled air might be too hot to cool the radiator efficiently?

The drawing of the whole car shows a fully streamlined Bonneville style car, which is the only context I could see a system like this having any benefit. And even then, maybe not with a miata.

The guiding principle for my build is to make it as light, small and simple as possible, and obviously this crazy scheme would nullify that.

Oh well, enough turbo pipe dreaming for now.

I have my boost button built into a little pedal that I push with my right foot. When I want more boost, I push that pedal harder / farther.

Works pretty well.

Clever.
So you're heel toeing it? You use the right foot to operate both at the same time?

No, it is the gas pedal. My point is that the control you desire already exists in the throttle + throttle based boost control.

At 3000 RPM and above, The car runs atmospheric manifold pressure at about 20% throttle opening. Then, more throttle position = more boost, linearly to 2 atmospheres.

Punching the throttle with that set-up yields the same result as pushing a button on the steering wheel.

Why go through all of that extra plumbing/trouble for something that I don't think will work as you intend. Why not have a normal turbo setup with an EBC that's set "open" until you close the contacts on a switch. That way, you're NA until you hit the switch, the EBC closes and you're at full boost. Potentially dangerous to your engine? Yes. But you'll have your "turbo boost" like you want.

That sounds like a better plan.

Maybe it wouldn't be so bad for the engine if it was a small turbo with a full boost setting of 5-8psi?

Minimalist System
 

What if I had a minimalist system like this? A bare minimum turbo that when activated would give a full boost of only five lbs.
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R56 Mini coopers use a vacuum actuated wastegate and a camshaft driven vac pump for power, spring pressure holds the wastegate open and vacuum will close it. They can almost completely cut boost pressure when something goes wrong.

You can't interrupt a pressure driven wastegate, it will run the boost pressure it's set at and no less.

Of course you could just use the throttle...