anyone ever twin-charge a 3800? had a turbo with the supercharger?

quote Originally posted by jeffdean42: anyone ever twin-charge a 3800? had a turbo with the supercharger?

Yep.

Sppdy's








original link here:
https://www.fiero.nl/forum/Forum1/HTML/044129.html

[This message has been edited by madcurl (edited 06-21-2010).]

yep....

For the record, in engineering talk, it is "bi-charging" not twin, as you are going to be neutralizing the pressure across the blower with the turbo, rendering it useless .5-.75 seconds after you hit the gas. Sad part is the SC does not help with spool time much, it just helps eliminate lag, which with a turbo smaller than 600whp, is nearly non-existent.

There was a "hellion" twincharge mustang article floating around that was mostly debunked as bullcrap as they claimed they made "50psi of boost" under the blower, and 35psi into the charge pipe.

so should i just do twin turbo instead?

Twin charging does work, its just more complicated. It will look good at a car show, Its just not going to make any more power than a single turbo. I don't see a need to twin turbo either unless you are shooting for 800+whp. There is going to be more parts, more weight and more money into something that a single turbo will do.

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Turbo 3800 E85 5spd spec5
11.53@126.7

quote Originally posted by darkhorizon: For the record, in engineering talk, it is "bi-charging" not twin

'Compound' is also used, but twin is fine...

quote Originally posted by jeffdean42: so should i just do twin turbo instead?

or you would have less lag with just a single.. I do not know of a single twin turbo 3800 anymore... the 2 that were running around were quickly swapped for single turbos.

The math is pretty simple... Stock supercharged motor/trans + 1 $100 turbo + a few hundered in turbo parts = mid/low 11's@121+ in a fiero. I get just as much boost in first gear as I did with the supercharger, not that you really even want boost in first gear.

Overcomplicating things would mean you are trying to run really fast, which requires you to know in advance if you needed to twincharge or not. What I mean by that is, if you are asking a simple question like this, you probably are not going to be running in the 10s.

Ok this may seem like a noob question but on a setup with a turbo/ supercharger aren't you limited to how much air the supercharger can move?
If you pump all the air in the world via the turbo aren't you still limited to the superchargers revolutions?

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You have the boost bypass open the valve when it sees X-psi from the turbo so will bypass the rotors.

quote Originally posted by Justinbart: You have the boost bypass open the valve when it sees X-psi from the turbo so will bypass the rotors.

Thats what I needed to hear. I still think it would be a bit restrictive though.
If some one was really concerned with lag, why not run a sequential turbo set up?
Get the smaller one turning then bypass it when the bigger on gets up to speed.

nissan made a tock bi charge motor, and there is a bmw with that set up i think and it is scary fast

quote Originally posted by Hockaday: nissan made a tock bi charge motor, and there is a bmw with that set up i think and it is scary fast

Here is everything and anything on the BMW set up.
http://www.e90post.com/foru...owthread.php?t=38856

Porsche 959, Mazda RX-7, Supra, and JDM Subaru all used a sequential set up.

EDIT: Thats 1,000 post boys.

[This message has been edited by Fiero_Fan_88 (edited 06-22-2010).]

Or if you are concerned with lag you can get a turbo with a variable geometry exhaust housing. Tight for fast spool then opens up so it will breathe

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Turbo 3800 E85 5spd spec5
11.53@126.7

quote Originally posted by Fiero_Fan_88: Ok this may seem like a noob question but on a setup with a turbo/ supercharger aren't you limited to how much air the supercharger can move? If you pump all the air in the world via the turbo aren't you still limited to the superchargers revolutions?

Also the blower is positive displacement.. so on top of moving the air it can move, it can also move compressed air with ~100% efficiency.

quote Originally posted by darkhorizon: Also the blower is positive displacement.. so on top of moving the air it can move, it can also move compressed air with ~100% efficiency.

LOL... please stop spewing bullshit.

Our 04' Audi A6 is a 2.7 Bi-Turbo. Just saying...

quote Originally posted by Will: LOL... please stop spewing bullshit.

It is true, when the blower has the same pressure on top and underneath, there is a "neutral" load on it, creating no increased air temperature. There is a slight amount of power loss, but not much different than a extra heavy flywheel at that point.

If you could find math otherwise, enlighten me.

The blower is ALWAYS moving more volume than the engine. There is no condition in which it has the same pressure above and below (well... maybe idle, but it will ALWAYS have mechanical parasitic drag).

After a little more thought, I just realized that what I said in the post above is incorrect. The blower will ALWAYS move more volume than the engine, which means that when the turbo boost comes up and the boost bypass opens, it will really be bleeding excess boost created by the supercharger, and NOT allowing turbo boost to bypass the supercharger. IOW, flow will be backward out the boost bypass, not in through it.

This creates excess drag and charge heating.

Good point, I didn't think about it that way

Awesome article on math involved for twin charging:

http://www.superchargerperf...urbocharger-goodness

Awesome Forum with the ins and outs of twin-charging explained:

http://www.eng-tips.com/vie...m?qid=198474&page=21

Just have to remember to stack your efficiencies.

If the compressor is 80% efficient and the blower is 60% efficient, your charge temp will be as if compressed by a system with 48% efficiency. You'll ALWAYS get cooler charge air with the turbo operating by itself.

For the record, the few guys that are running twincharged setups have the same manifold pressure above and below the superhcharger.

And how's that measured?

Like I said, open up the bypass and you might get close, but you'll be wasting power turning the blower and bleeding off "boost".

HMMMM OK I have a ? then, Would the car owned by spddy be a good candidate for city driving?? If the engine were going into a show/driver could one count on it as being reliable? Mind you it would NOT I repeat NOT be used for any street or other racing!

I need an answer QUICK

quote Originally posted by Will: And how's that measured? Like I said, open up the bypass and you might get close, but you'll be wasting power turning the blower and bleeding off "boost".

pressure port below and pressure port above the blower. The zzp twincharge controller box has provisions for this.

You dont really waste much power, as the blower is just a blender at that point, and you get some "ram air" type gains i would imagine. The peak efficiency of the blower at best is 55%, and most turbo's of proper size will crank out nearly 75% efficiencies. The blender blower tossing out 2-3% in heat for the ~0.1 boost it makes, is still paid back by the big gain offered by the turbo, and in turn the turbo's superior intercooler.

Twincharging "works" it just offers little to no significant gains. It is not hard to do if you are not intercooling the blower either..... I just wouldnt attempt it as someones first jaunt with a big turbo 3800.

Unless you have either worked on one of the systems directly or built one you guys are perhaps speaking theoretically. And I mean 3800 turbo and blower (in this case an M62/90/112). Chris West designed spdy's setup yrs ago and ZZp built their own setup following that; two completely different setups and outcome. Chris did not use a bypass and ran a combined boost of 12-14psi.
The turbocharger compresses air above roots blower and blower MOVES this air now at a higher PR into intake while compressing it further. I don't remember much of the way the boost was split...but the SC would not heat up the charge as much as it would have anywayz. Bypassing the SC ALWAYS lowers power output, but that maybe a necessary evil. It all depends on your goal...this was just a "let's see what we can do" rather than an ALL out power fest! however it is doable, one just has to realistically look at the advantages or disadvantages before plunging in.

go to any engineering forum and do a bit of research on your own

try http://www.eng-tips.com/sea...71&requesttimeout=75

quote Originally posted by darkhorizon: pressure port below and pressure port above the blower. The zzp twincharge controller box has provisions for this. You dont really waste much power, as the blower is just a blender at that point, and you get some "ram air" type gains i would imagine. The peak efficiency of the blower at best is 55%, and most turbo's of proper size will crank out nearly 75% efficiencies. The blender blower tossing out 2-3% in heat for the ~0.1 boost it makes, is still paid back by the big gain offered by the turbo, and in turn the turbo's superior intercooler. Twincharging "works" it just offers little to no significant gains. It is not hard to do if you are not intercooling the blower either..... I just wouldnt attempt it as someones first jaunt with a big turbo 3800.

Temperature probes to verify efficiency?

There was in zooms car, I dont remember the outcomes. They were running an underblower intercooler because of a fairly small pulley so I imagine there was some issues there.

There was a "hellion terminator twincharge" article floating around somewhere, and they had some mustang making "50psi" and barely making 1000whp... Which there is something wrong there as many single/twin turbo mustangs are able to do that at less than half that intake manifold pressure.

CFM and temperature is what really rules here, so it really is not all that complicated math wise.

OK come on guys BUMP for my ?

Will says it's not a good idea the way this engine is setup with the Twin Charger, What do you othe experts have to say, I would like to know if this setup is a good running setup. I have heard the car run and it sounds like "A BEAST"

Thanks

there are newer small displacement motors being built in Europe that use this form of twin charging : in the lower RPM ranges , the motor is chaged by a supercharger .at higher revs the suercharger is shut off via an electric clutch and the intake closes the path through the SC and charged air comes from the turbo only .the only real advantage to this system is that you get the feel and power of a 3.0 L motor in a motor that is only about 1.3 L .these motors are also direct injection .with a 3800 cc motor i cant see any advantage to doing this .

Do it if you want. Run two intercooler systems and have the bbv open at x-psi. Make it real shinny and people will look under your decklid and say "OMG twin charged, this thing must pull wheelies. I knew a guy who had a v8 in his"

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Turbo 3800 E85 5spd spec5
11.53@126.7

My other "option" is purchase a 6-7k mile 3.4L DOHC w/ turbo, engine is supposed to be smooth running and does have a little lag until around 3500 rpm. One thing about the 3.8 w/ turbo I don't know how reliable it may be. That is a concern, since the 3.8 does not have very many miles.

hmmmmmm