centrifugal superchargers and TB position

[barryogen]

After searching and not finding a hell of a lot on toyspeed with anyone actually using one, I thought I'd post "dyno" plota of a 2zzge(in an MRS/MR2 Spyder of all things) using a rotrex c30-94, a "blower" meant to be suitable for ~400HP at the crank.

http://www.xtendednet.com/spyder/Rotrex_2zz_dyno.jpg

Certainly looks like an interesting SC to be using, having much less piping than a turbo in a 2zz(intake in front, exhaust against the firewall).

Now, another question I have is where would you put the TB, they alway seem to put after market SCs in this order.

Filter->SC->IC->BOV->TB->engine
Using the BOV as a bypass valve to vent when on vacuum, but there seems to be a bit of confusion as to whether or not the TB should be before or after the SC... but I can't see it working before the SC, as then you would have the SC sitting there trying to pull air through the TB while it is closed, whereas with the above setup, it would atleast be able to vent to atmosphere via the BOV, albeit probably not quick enough, so maybe multiple BOV would be needed.

[Crampy]

You put the Throttle before a positvie displacement supercharger, as it will blow the throttle plate or intake pipes off when you close the throttle. You can away from this if you use a bypass valve or BOV, but they'd be noisy.

The rotrex is the same compressor design as a turbo (just no turbine, it has a gearing system instead), so just put the throttle body in the same place as a turbo car (The way you mentioned).
Use a BOV and away you go.

How much are these babies? I've heard a few people mention them now.

[barryogen]

How much are these babies? I've heard a few people mention them now.

not cheap...
2200USD, so ~3k NZD at the moment.

I just love the idea that the higher you rev, the more it has, it sounds pretty much like my car in NA at the moment, hence it appeals to me.

[Crampy]

How much are these babies? I've heard a few people mention them now.

not cheap...
2200USD, so ~3k NZD at the moment.

I just love the idea that the higher you rev, the more it has, it sounds pretty much like my car in NA at the moment, hence it appeals to me.

That is expensive, however you could weigh it up with how much a turbo conversion will cost (from memory you were planning on going turbo). With the supercharger, you can keep the exhaust manifold, but need to be able to mount the supercharger somewhere.
With the turbo you will need a turbo manifold and oil and water lines, not to mention the turbo itself, dump pipe, etc.

I'd have a guess and say turbo might be cheaper, but you'd have to consider everything in each setup before that can be proved.

Either way, I'd say it'll be a great project to take on, supercharged or turbo.

Good luck dude.

[barryogen]

both seem to end up costing about the same amount.

The mounting of this SC is fairly easy, it fits where the AC is currently, and AC can be made to site just below it, only one pipe needs replacing.

The reason why I'm looking at these sorts of thing is that I know I'll have issues with traction going turbo, unless I can make it have a much smoother torque curve... which these things would be ideal for.

One thing that did seem interesting with them is guys who have used these in the MR2 Spyder, and lose traction at 7000RPM... eek.

[Mr Revhead]

t/b before the s/c is factory on stock toyota s/c systems

having the t/b after is better imo. better throttle reponse etc

have a bypass valve between t/b and s/c
but plumb it back in!! or itll sound a little dramatic!!

[barryogen]

have a bypass valve between t/b and s/c
but plumb it back in!! or itll sound a little dramatic!!

yes, I have heard mention of F14s as they hiss along the road.

[Crampy]

You can buy turbos that don't come on a strong as others. With a big turbo, it'll kick you in the arse like nothing, but with a smaller turbo, it'll spool earlier and your torque curve shouldn't be too bad.