Root/screw type charger with Twin Turbo

[304runner]

Hi everyone, I was having a bit of trouble sleeping last night so I thought id have a little dream of my own...
I was wondering why I havent seen or even heard of a 304 (or anything for that matter) with a root or screw type supercharger attatched to it boasting a turbo off each bank?

With money not an issue could this be done at all or is it a waste of time?

The first thing I think that could be an issue is head flow? Then fuel, not to mention traction ect....

Has anyone seen it done?

You could have massive turbos on both banks, as the charger would eliminate the lag so in theory it makes perfect sence.....

Discuss...

[soop]

Its been done.
There's certainly bigger issues then fuel flow too, keeping the bottom end together and the heads on the block for one.
So long as you're not using carb heads, its not a massive issue. Though I'd hazzard a guess that if someone actually did do this they would be looking to make substantial power, so head work is going to be needed, or a set of aftermarket heads.

In all honesty, Its easy to use either/or. I've helped a mate do a similar thing to a Holden 355. And it really is less arsing about to just use one or the other. Just having the supercharger doesn't eliminate lag. By having the supercharger you essentially increase the displacement of the engine (as far as gas flow is concerned) so you'll need bigger turbo's to compensate unless you want to run them right out of their efficiency range or have them strangle the motor in the top end.

[immortality]

it is actually a good idea and has definitely been done before (although not sure on a Holden 304).

with this type of setup the screw type blower looks after the low rpm stuff and then the turbo's kick in and as the blower get's past it's efficiency range. in effect, the blower will help to spool the turbos because turbos work of heat and having the blower on will create more heat in the exhaust then without the blower so the turbo's will spool faster.

these days though with either setup you can make bulk power. modern screw blowers and turbo's are much better then those from yesteryear.

[304runner]

. Just having the supercharger doesn't eliminate lag. By having the supercharger you essentially increase the displacement of the engine (as far as gas flow is concerned) so you'll need bigger turbo's to compensate unless you want to run them right out of their efficiency range or have them strangle the motor in the top end.

Well surley having a top mount supercharger is going to prevent lag, its producing boost at idle so in that respect it has to...And if your saying that a supercharger is "essentially increasing the displacment" then that would obviously apply to a turbo too right....? Im aware of what the two do I just find it interesting to have someone put it that way....

[VN_Luke]

damn I wrote an epic post about this but it took too long so I got logged out and lost it when I submitted

so I'll just whack this in here.



my twincharged results

From firsthand experience I can tell you that the theory works quite well.

As for the "is it worth it" question - it really depends what you're planning to do with the car.

For example, if you're building it to go drag racing only - you'll probably find you can run quicker times with a cheaper turbo-only setup.
Same if you're building for peak power dyno numbers...

If you're after a crazy flat and fat torque curve and want to challange your imagineering skills - then it migh tbe for you


as for how it all works.....
essentially all you're doing is giving the supercharger a massively DENSE volume of air to feed into the engine. (imagine a supercharged plane engine and how it behaves at different altitudes).

The turbos don't have to work as hard as they're only providing say... 'half' of the total boost that the intake sees.
The engine runs safer and has potential to make more power due to the exhaust backpressure being down since the turbo doesn't need as much energy to power it, since it's only working half as hard..

[304runner]

Fark..... 359 RWKW out of that lil thing is awesome.....

[soop]

Well surley having a top mount supercharger is going to prevent lag, its producing boost at idle so in that respect it has to...And if your saying that a supercharger is "essentially increasing the displacment" then that would obviously apply to a turbo too right....? Im aware of what the two do I just find it interesting to have someone put it that way....

The problem is you're increasing the amount of exhaust gas by increasing the air and fuel volume. So you'll be needing bigger turbo's unless you plan to use less rpm (making the excersise redundant). At the end of the day it evens out, you will make more power but in the same way.

[VN_Luke]

The problem is you're increasing the amount of exhaust gas by increasing the air and fuel volume. So you'll be needing bigger turbo's unless you plan to use less rpm (making the excersise redundant). At the end of the day it evens out, you will make more power but in the same way.

Instead of going bigger turbos to try fix the issue of smaller ones 'choking' the exhaust path, why not just use a decent sized and good flowing wastegate setup?

This is pretty vital in this kind of setup anyway to fix "common" on-spool boost spikes that are amplified by the compound boost setup.

Naturally if you're only going for the most possible power you can make, bigger snails are the way to go, though

In "theory" a compound setup should make more power than turbo-only by giving you a big advantage on the 'inlet' side of the 'inlet:exhaust' pressure ratio - which means less chance of residual exhaust gasses superheating fresh intake charge, and a safer running engine that should be able to take more timing, and make more power - compound charging is old news in the diesel world, because of it's ability to get bulk inlet pressures without restricting exhaust too much.

I say in "theory", tohugh - because I've not experienced this phenomenon first hand with my setup yet - I have a few ideas as to why this hasn't happened, and will experiment with these on the current build.

There's companies in the states doing compound setups for various cars - including hellion power systems with a compound setup for an '03 mustang - almost 1200hp through a stock engine, including stock cast exhaust manis!!!

Compound Boost 2003 Mustang Cobra Twin-Turbo - Muscle Mustangs & Fast Fords Magazine

But yeah, at the end of the day - if you're all about the peak power number, there's much cheaper and easier ways to get it than a compound setup

[soop]

In answer to your first question.
Can't fit a big enough waste gate and pipe into the engine bay of a Torana. But yeah, I see your point.

[VN_Luke]

In answer to your first question.
Can't fit a big enough waste gate and pipe into the engine bay of a Torana. But yeah, I see your point.

any pics of this setup? sounds interesting!

anywya - soft! - who said it has to be contained within the engine bay! ... this isn't twincharged - but you can see where I'm heading with it lol

[soop]

Hahaha, I don't have any no. We did this about 5-6yrs ago and we're both on opposite sides of the country now unfortunately.
Base engine was a 355 stroker with a 4/71 and two garret GT32's. Which all fit under the bonnet with an A9X scoop to clear the charger. It wasn't pretty at all, but worked quiet well for maybe a year before frequent abuse took its toll.

[304runner]

Any pics "soop"