You know, this business of defending an experimental idea was exactly what I did not want this conversation to turn into, when I first asked about the value of intercoolers.

Originally posted by Rara:
So, for Paul's assumed 35kPa boost pressure we get the following.
Pt = 5.00kW
Now, typical centrifugal compressor efficiency is something like 65% so:
Ps = 5kW/.65 = 7.69 kW at the electric motor shaft. This is roughly 10.3 hp required from the motor.


That's just about the same number I came up with by taking a rough guess at the inefficiencies. In summary, with either your figures or mine, it's at the difficult end, but certainly not impossible.

Originally posted by Rara:
Now, assuming your 12V system, this is roughly 650Amps running ANY TIME you wish to have boost,


Correction, not ANY time you have boost, but any time you have maximum boost at high RPMs. 90% of the time the demand is lower. (One advantage of electric boost is you can regulate the demand to exactly fit the need, instead of taking too much and throwing away the part you don't want, as all mechanical boosters do in some parts of the powerband.) And note also that if the system fails to give you this much power, that only affects the high end; you might have 6 psi at 4000 rpm and 4 psi at 6000. Since the car's present behavior is that you really feel an increase in pull as you go above 4000, that could still help quite a bit.

Originally posted by Rara:
Now, Paul was looking for ~200hp w/ his 5psi, and that ain't gonna happen,


Of course it's not. I never said I expected 200 hp, I only said I had no interest in anything beyond that.

So never mind the second, higher boost scenario.

Originally posted by Rara:
Oh, I also failed to mention, that your typical centrifugal compressor will be spinning well over 100k rpm to meet these flow requirements, and whatever magical wonder motor paul chooses to run will need to be even bigger to account for the additional losses due to the required gearing to run the compressor at the appropriate speed.


I was figuring on using a belt. Is that bad? And I thought it was only like 30k rpm... If it's 100k, that means gears, which would be more difficult and annoying.

Originally posted by Rara:
You have been whining about the cost of an intercooler becuase you want to do your project cheaply, but really, do you think even a version of this that doesn't even work well is going to be cheap? An intercooler, even a new one from spearco, will be a drop in the bucket compared to the cost of the required componentry for this sort of a setup.


I thought we settled the intercooler issue a month ago. I already told you I'd use a basic air-air cooler. If you're going to talk down to people, it helps to listen first.

Originally posted by Rara:
High current motors, custom compressors and gearing, much larger alternator, 2nd battery, high current electrical distribution and control components, most all needing to be custom made.


Depending on how much I use it, there may not be that much need for a larger alternator. Other users might want one.

As for the custom making, that's just hobby value. There's not much I'd have to farm out to anyone.

Originally posted by Rara:
All for the same amount of hp that could be had in the other motor offered in the car stock, and all the time, not just for extremely short bursts of time. And to top it all off, you still wouldn't be legal to drive the car in california. Though, you could anyway, and really piss off all your neighbors over in Berkeley.


I guess your suggestion is to buy a different car.

Hell, my CTA intake isn't legal in California, and this system could pass the same way the CTA did last time: unlike a turbocharger, it can be easily dismounted.