Just bought a heap of gear to supercharger the old girl

Question - Which engine is best to charge in near standard trim,
A12?
A14?
A15?

try typing supercharge in the search bar- there are heaps of topics on the subject.

Yeah, there's a lot of good info scattered around this site.

Quote:This might be a new question, I don't recall that it's been asked before.

I would think that none have an advantage over the other. All these engines will respond to supercharging equally well, and packaging the gear will be nearly identical.

Of course, there is an advantage with or without supercharging: the A15 is 25% larger than the A12, so you'll get more power over the usable RPM range with the A15.

i heard the superchargers (4agze particularily) are out of there efficiency range at around 7000 revs, so theres no point going an a-12 for higher revving

correct me if i'm wrong. but if a supercharger is at its peak on a 1600cc motor @7000rpm, then on a 1200cc motor its peak would be higher. calculating cfm ouput to match the motor.

Max boost, yes.

Max blower speed, no. For a supercharger the max speed of the blower doesn't depend on what size engine it is on. 7000rpm is 7000rpm, whether it's a 1-liter or a 5-liter. A turbo is different, the exhaust gas drives it to maximum speed (it's not directly tied to engine RPM).

Got me thinking that the Toyota 4A is a 1.6-liter engine, so it would seem the A15 would be closest in size to the original application for that blower. It would hit your boost limit sooner (at a lower speed) on a small engine than on a larger engine. Which might be good ... make max boost quick and keep it up to 7000rpm. You could change the pulley sizes to compensate if you wanted to rev even higher.

What's the smallest blower that's commonly available?

Hey Toddat an a15 has lower comp than a n a14 so that might be the go . Depending on the parameters of your blower you could do an a15block with an a14 crank and rods . Check out ferrals formula in the thread about s/c 1400, its an excellent guide for blower drive combos. I calculated that the s/c14 (1gg-ze on my 1400 would produce 16.7psi at 1-1 ratio.This is well beyond what the blower is capable of.

my understanding is the longer the stroke, the lower the boos you can use. an a15 comnpared to an a12 may make power butt a built a12 will make it with higher boost.
longer rods may also have problems with "bending" under boost.
these are stock items im talking about and from my research, not experience

Keep in mind that is blower RPMs not motor RPM.

Longer stroke engines will benefit nicely from positive displacement blowers as the torque figures go through the roof, & believe me, it's a bloody good feeling.

Blown hemi Chryslers don't need any more than about 5,500 rpm because they make great gobs of torque due in part to a stroke slightly shorter than my arm. When they run out of revs, just grab another gear & hang on tight.

An A15 will proportionally respond in a similar way. Don't rev it, stroke it.