lag can be non-exsistent on a car that is fitted with the right size turbo and is tuned correctly (like you said). boost creep is not common with all turbo engines. boost creep is when there is not enough exhaust bypassing the housing, not because its a turbo engine. 2 turbos is not a waste on a v type engine if they are sized properly and it reduces alot of that plumbing as well.

Wow, a couple year long thread. I think some one asked for a streetable 1000 turbo car, how bout this one right here? And its not a Supra "myth". This also shows that boost cand be changed on the fly to produce 2000 hp. By the way, it runs on pump gas to make 1000 at low boost. Enjoy.

And 6 months later another crazyperson comes along and dig it up again...

I'm in a predicament at the moment. I have to make a choice between going SC or TC. The natural thing for me to do is read up on things. This here forum is one great source of information by the way.
Now there are a few things that I feel this discussion is lacking and that is the fact that all cars are not about all out power.
I'll use my car as an example. (It's a 2.3L engine by the way)
If I go higher than 400hp it will kill the engine pretty much. I risk bending or breaking the connecting rods or blowing holes in the pistons.
So, knowing my limitations how do I get the most out of my engine? Forced induction is a must of course...
A Roots blower is to innefficient, sorry.
A centrifugal blower? I don't know much about theese.
Now besides reading some more about the centrif. blower I'm left with two choices.
1) Going Turbo or
2) Trying the Lysholm Twin-Screw SC.

To get approx 400bhp I need 40lbs/min of air.
Using a turbo I can use a 24psi boost and get my cfm@6000rpm give or take a hundred rpms.
If I go for the SC I soon realise that we have a problem. The Lysholm SC doesn't like boost above 18psi. This forces my top power output into the 7000rpm range.

Like we all know a SC will steal some power, in this case I would estimate 36kW at top rev. (50hp) Thus leaving me with a top figure of approx. 350hp.

The Turbo will cause backpressure that limits the high end output but I don't think there will be any problem getting the hp anyway.

We're left with 350 vs. 400 hp, right?
Now comes the hard part. The turbo will heat the air a great deal more and heat means loss of power. The turbo will need a lot more plumbing. A good turbo is just as expensive as a supercharger. (Looking at the ballbearing turbos now, at least where I live)
The turbo will have a lag.
The car will mainly be a street car but I'll run it at the strip maby once or a couple of times each year just for fun.

The SC will give me less hp at higher revs but It'll deliver all the way, no lag what so ever. When I step off the clutch I'll have my 18psi boost right away. Oh... the air is a lot cooler which means more power.

Which one is the best? I don't know? I told you I was having a problem choosing.
I don't have the experience or the knowledge to calculate the effect the temperature of the air will have. I have intercooling of course.

My purpouse is to show that "all out power" isn't allways the goal and it brings out new problems.

Oh, and one more thing.
A boost is a boost, it doesn't matter where it comes from.
If you use a waste gate to regulate the boost. You put restraints on the turbo. A turbo@18psi boost gives the same amount of air as a blower@18psi boost. (The charge density may be different due to heat.)

Confusing?
My bad...

Centrifrugal superchargers work the same way a turbo does, the diff is that the centri uses the crank to spin it instead of exhaust. Your gonna have some parasitic lose using the centri but you can still get to 400hp that way.

A Lysholm will make more than 18 psi if you spend the money to build one to live at those boost levels. The g60 units used by VW on the carrodos and rallye golf are a great chargers but require some work to spin high boost. Bahn Brenner Motorsports is one of the best lysholm guys in the states.

I say you should go with a turbo just for ease of install, reliability, and cost. I would also recomend some good forged internals as well. Good luck!

Thanx.
I've done some looking around and it does seem like a Lysholm set-up will be quite expensive. There were some hidden costs...
But I really liked the idea of a supercharger.
It does seem like the tubo is the only sensible solution.
It's cheaper, will give more power, and if I opt for a really hightech turbo the lag will be almost gone. Full boost @ 3000rpm perhaps as low as 2500rpm.

i dont know much about either a turbo or a super charger except that a turbo runs off exhaust commen knowledge. since a turbo runs off exhaust it causes a slightly more heat then a s/c. one of the good thing about a turbo is you can adjust the boost from inside the car. where as a s/c runs off a belt and pully. which im guessing would cause slightly less heat. but unlike the turbo in order to change the boost on a s/c you have change the pully on it smaller pully more boost vis versa. well i know this probly isnt anything you didnt know. but i thought i would through my 2 cents in. =p.

Yupp, changing pully sucks but SC are really cool.

An interesting discussion and I'll have to catch up on all the replies.

Something I didn't see in mentioning the turbo is the fact that the turbo uses the exhaust gas to do work, ie spinning the compressor. With a sc, you are using the power of the engine to spin it, and hence reducing the amount of work available for the tranny on out to the wheels. With the turbo, you are using the exhaust gases which otherwise are just dumped out of the exhaust.

Assuming you can only run so much boost on an engine, the turbo will win the power at the crankshaft, because power isn't being robbed to spin the compressor.

Well Guys -- New here and first post -- but I'll let you know how it's going for me later this year.. I have a 406 Cu inch SBC Rail dragster - and feeding it with a Turbonetics T-76 Turbo (Q trim .96 A/R) with current plan up to 15psi - on Alcohol fuel -- and will be testing this spring -- I am planning to just run "Brackets" on an NHRA track - and the rules DO allow for this single power adder.. Looking on the internet I have only found Three other "Rails" trying out a turbo (one of which is in Australia) -- I guess because of the current rules at higher classes etc.. But I just want to go out and play with the Big Block boys -- running 800-1000 HP - and the Guru's tell me that on Alcohol (super cools the fuel charge) that that is well within my range.. SO -- if interested I'll let you know how its' going and You can decide for yourselves...
My advantages -- I don't have the concerns that you have been discussing - Heat and space --to do the plumbing - it's all in the open and the Alcohol reduces the "HEAT" from compressing the air charge.. I think the Turbo will be easier on on engine over time - - hey they go 100,000+ miles on factory cars. BUT MOST OF ALL -- no-one else has one, and isn't that a basic fundamental of "HOTRODDING" trying out new things - innovation and improving... Maybe the NHRA will come around -- and I'll be the first one over 350mph -- running a turbo..
Keep exploring and use your imagination - & Make Don Garlits smile..

In the end I bought myself a Lysholm AX-1600 Twin Screw S.C.
Very cool unit
It's been a while since I read this thread but seeing someone brought it back to life again...
Don't forget that a turbo suffers from backpressure or whatever it's called in english? There is a pressure buildup between the exhaust valve and the turbo since the turbo acts kind of like a restrictor.
This forces the engine to do work in order to push the exhaust gases out of the cylinders.
With SC there is no such thing and the exhaust runs smoothly.
There is no such thing as a free ride...

I'll give you a real world examlple of what a basic turbo will do to a normal car. My daily driver is a 89 Nissan Maxima. I turbo charged the stock engine with 181,000miles on it. The engine is a 3.0L V6. I'm usto working on Buick Grand Nationals so I used in Buick Terms a TA 49 turbo which flows 800cfm and supports around 550hp on a Buick V6 engine. This turbo is the next step up from stock for most guys.

My Nissan factory ran a 15.70@87mph in the 1/4mi.
It now runs 13.40@107mph in the 1/4mi. (107mph would put it in the 12s with proper launch.... traction is limited being FWD)
I retain my gas mileage before I turbocarged it. (with in 1mpg) when I'm not beating on it obviously... aound 22mpg in town and 28mpg on highway.
I now have 226,000miles on it and still put 12psi of boost to it every day.
Sure makes Alot of foolish V8's cry when I tell them it's a stock V6 with "bolt on's"

The newer belt driven (non roots style) would be the only way I'd ever supercharge anything but that would be a last resort. And a huge waste of money IMHOP.
That's my take,
~Scott

In the end it's all about engine character.
On a normal engine the turbo WILL give you more power but with a narrow powerband compared to a twin screw sc.
A rotary sc is pretty much a waste of time and mony since it's just a belt driven turbo...
Over here in Sweden our carpark looks very different from the one you have in the U.S. Most cars around are 4cyl because of the price on gas.
That does give some interesting effects though. We have people running 2.3-2.5Liter 4cyl. engines with more than 1000hp. Yeah, I kidd you not. And they are almost always turbocharged. 12psi doesn't even count as tuned, it's pretty much factory standard.

The turbo will give more power but most of the time the cars are not very fun to drive except at the dragstrip. They are to much race.
Nothing happens below 4500-5000rpm.

So, when choosing between SC and tc ask yourself how you want the engine to behave.

So how did everything go with the lysholm?

It's not ready yet.
I need some aluminum welding to be done and it takes time when you're relying on other people to do it...

well it's been a year later so let's try this again, "So how did everything go with the lysholm?"