TWINCHARGED (Supercharged & Turbocharged) Widebody "WTF-86" 86/FRS *MASSIVE* build :D

[Jaden]

Originally Posted by killboy

Not a jab, I'm genuinely curious as to what your background/resources are in this area.

I've worked on compound boost setups on diesels that were 100+ psi.

Slightly different concept, but the same rules apply.

Jaden

[JustAnEngineer]

Originally Posted by Jaden

A compound boost setup done right is amazing on low displacement engines, unfortunately, few people know how to do them right.

Care to share any examples of good compound set ups? I find them quite interesting but they're few a far between. I know the Lancia Delta S4 was the first and the never to see production Jaguar C-X75 was too. And this custom Lotus used to be as well but that was a one off.
[ame="https://www.youtube.com/watch?v=HmscSzFurwg"]Lotus[/ame]

All these seem to make crazy power albeit very complex. But these cars made 480 hp, 500 hp and 700 hp respectively in engines under 2 liters. And the dyno curves probably look insane too.

[the_one_mike]

Originally Posted by JustAnEngineer

Care to share any examples of good compound set ups? I find them quite interesting but they're few a far between. I know the Lancia Delta S4 was the first and the never to see production Jaguar C-X75 was too. And this custom Lotus used to be as well but that was a one off.

All these seem to make crazy power albeit very complex. But these cars made 480 hp, 500 hp and 700 hp respectively in engines under 2 liters. And the dyno curves probably look insane too.

As far as I know, the Lancia Delta was not compounded boost. The supercharger was deactivated by a bypass valve when the turbo made boost. Each are separate entities and not linked together as seen on this and other projects.

[Jaden]

http://www.fitfreak.net/forums/other...73-140mph.html

2.0 liter compound boost running 9's at 37 psi..

There's also one I can link to that was running 8's at only 600 hp because of the torque curve...

Jaden

[the_one_mike]

Originally Posted by Jaden

http://www.fitfreak.net/forums/other...73-140mph.html

2.0 liter compound boost running 9's at 37 psi..

There's also one I can link to that was running 8's at only 600 hp because of the torque curve...

Jaden

You're keeping my dreams alive.

I don't want to seem like I'm taking a shot at any manufacturers here, because I'm not, but I suspect that quite a bit of the problems that WTF ran into during the build was relative to the supercharger equipment...

Is the sprintex the only twin screw S/C out there? I know there are other PD superchargers available, but roots and TVS blowers won't further compress a charge like a lysholm style would... It seems like the supercharger is certainly the key aspect of making a successful and stable compound boost on the twins.

[JustAnEngineer]

Originally Posted by the_one_mike

You're keeping my dreams alive.

Is the sprintex the only twin screw S/C out there? I know there are other PD superchargers available, but roots and TVS blowers won't further compress a charge like a lysholm style would... It seems like the supercharger is certainly the key aspect of making a successful and stable compound boost on the twins.

Can you elaborate why twin screw compresses better than twin vortices?
Also, correct me if I'm wrong I just learned the difference between the two but it seems you're advocating a lysholm style which is a twin screw which the sprintex supercharger is, which is what they used? So how come you said that's where they had a problem?

Not trying to argue, just trying to learn some stuff.

[the_one_mike]

Originally Posted by JustAnEngineer

Can you elaborate why twin screw compresses better than twin vortices?
Also, correct me if I'm wrong I just learned the difference between the two but it seems you're advocating a lysholm style which is a twin screw which the sprintex supercharger is, which is what they used? So how come you said that's where they had a problem?

Not trying to argue, just trying to learn some stuff.

Twin screw and twin vortices are just interchangeable terms. We are talking about the same thing. Lysholm is just the "technical" term for this style of supercharger.

The Sprintex seems to be reliable on its own, but there are commonly reported O ring failures, and something leads me to believe that introducing a turbocharge and subsequently increasing the internal pressure of the unit exponentially led to reliability problems in delivering a consistent boost.

[Jaden]

compound boost is doable with any style FI...

a positive displacement s/c would be best because of the linear boost. The way a pos displacement s/c boosts allows for max PR from very low rpms.

So long as it is the secondary, you don't have to worry about air flow. The key to a successful compound boost setup is having the right primary FI system.

You have to know how much boost it's going to be running and choose a system that has enough airflow at the boost level that that specific system will provide.

Oh wow. this just gave me an idea... Use a huge procharger as a primary and then a smaller turbo as the secondary. You control total boost on the turbo and the S/C will give a finite amount of boost based on Rpms...

The only problem with it is at lower rpms the turbo will be providing more boost. That might still be better.

Time for some espeerimentin'

Jaden

p.s. it is possible for the air to blow by the seals on the s/c in a turbo fed into a pos. disp. s/c setup like the ops and make it act funny or get less boost, so sizing of the s/c could potentially come into play, and or the pressure capability of the seals.

[the_one_mike]

Originally Posted by Jaden

compound boost is doable with any style FI...

a positive displacement s/c would be best because of the linear boost. The way a pos displacement s/c boosts allows for max PR from very low rpms.

So long as it is the secondary, you don't have to worry about air flow. The key to a successful compound boost setup is having the right primary FI system.

You have to know how much boost it's going to be running and choose a system that has enough airflow at the boost level that that specific system will provide.

Oh wow. this just gave me an idea... Use a huge procharger as a primary and then a smaller turbo as the secondary. You control total boost on the turbo and the S/C will give a finite amount of boost based on Rpms...

The only problem with it is at lower rpms the turbo will be providing more boost. That might still be better.

Time for some espeerimentin'

Jaden

p.s. it is possible for the air to blow by the seals on the s/c in a turbo fed into a pos. disp. s/c setup like the ops and make it act funny or get less boost, so sizing of the s/c could potentially come into play, and or the pressure capability of the seals.

My research on this topic could be incorrect (very well may be), but as far as I know any PD blower will WORK, but only a twin screw supercharger will actually increase the pressure of the inlet charge being supplied from, in this case, a turbo because it internally compresses the charge unlike other PD blowers that literally just displace air.

This allows for a rather low inlet charge from a small turbo to be amplified significantly on a linear plane, while another style blower would also provide the power on a linear plane but just "add" its own boost to the provided charge coming from the turbo as opposed to exponentiate it as a twin screw would.

As I said, my understanding of this could be wrong (I hope it is, honestly, for the sake of options for blowers) but I'm not sure here. Admittedly, this is fairly new to me as I've really only gotten interest in this since picking up my BRZ in April.

[killboy]

Originally Posted by the_one_mike

My research on this topic could be incorrect (very well may be), but as far as I know any PD blower will WORK, but only a twin screw supercharger will actually increase the pressure of the inlet charge being supplied from, in this case, a turbo because it internally compresses the charge unlike other PD blowers that literally just displace air.

I'm still learning too, no expert either, but my understanding is that if you send compressed air from a turbo into a roots-style (old school) PD blower, it will provide an increase in that boosted pressure and send it on to the engine, but not nearly at the rate a twin screw will increase the pressure/boost.

To quote a company info page that makes compound boost setups for Mustangs:

Q: Can I use a Kenne Bell or Whipple Supercharger with the Turbos?

A: Yes. Keep in mind though, there are some precautions to take with the larger, twin screw superchargers. The amount of air that a twin screw supercharger would flow through it, as well as the manner in which the twin screw superchargers compress air will lead to much, much higher total boost levels versus a roots style supercharger. This is an important factor to keep in mind when tuning the car for maximum power. Turn the supercharger slower with a larger pulley, and any potential issues should be resolved.

More reading for those interested:

http://www.hellionpowersystems.com/i...boost-resource

[Jaden]

Originally Posted by the_one_mike

My research on this topic could be incorrect (very well may be), but as far as I know any PD blower will WORK, but only a twin screw supercharger will actually increase the pressure of the inlet charge being supplied from, in this case, a turbo because it internally compresses the charge unlike other PD blowers that literally just displace air.

This allows for a rather low inlet charge from a small turbo to be amplified significantly on a linear plane, while another style blower would also provide the power on a linear plane but just "add" its own boost to the provided charge coming from the turbo as opposed to exponentiate it as a twin screw would.

As I said, my understanding of this could be wrong (I hope it is, honestly, for the sake of options for blowers) but I'm not sure here. Admittedly, this is fairly new to me as I've really only gotten interest in this since picking up my BRZ in April.

Any compressor will compress the air coming into it at the PR that it compresses at.

The most common uses are multiple centrifugal based turbos...

Jaden

p.s. Also, you can't use a small turbo as the primary. The primary FI system pulling from ambient has to be able to provide all of the air flow you need at the boost level it will be running at individually. That's why I'm now looking at using a large centrifugal S/C as the primary because their compressor maps have such a broad range of flow in general and great flow at lower boost levels, I think it will be ideal with the more linear increase for compound charging.

[the_one_mike]

Originally Posted by Jaden

Any compressor will compress the air coming into it at the PR that it compresses at.

The most common uses are multiple centrifugal based turbos...

Jaden

p.s. Also, you can't use a small turbo as the primary. The primary FI system pulling from ambient has to be able to provide all of the air flow you need at the boost level it will be running at individually. That's why I'm now looking at using a large centrifugal S/C as the primary because their compressor maps have such a broad range of flow in general and great flow at lower boost levels, I think it will be ideal with the more linear increase for compound charging.

Can you cite any sources on this? Not that I don't believe you, I'd just like to read more because I don't fundamentally understand how a centrifugal blower could increase an inlet charge (at least efficiently enough to make it worth considering). You said that this is the most common use but I have had a hard time finding info on a setup done in this manner.

Also, Re: your p.s. ... I'm not sure what you are referring to as "primary." To me, the primary in the instance I described is still the twin screw, being as the turbo would be relaying a charge to it. The other way around and there is basically no point as you would still be dealing with turbo lag -- you would just be forcibly overspooling a turbo with a positive displacement charge. Maybe this is why you have suggested a large turbo so many times.

[the_one_mike]

Originally Posted by killboy

I'm still learning too, no expert either, but my understanding is that if you send compressed air from a turbo into a roots-style (old school) PD blower, it will provide an increase in that boosted pressure and send it on to the engine, but not nearly at the rate a twin screw will increase the pressure/boost.

To quote a company info page that makes compound boost setups for Mustangs:


More reading for those interested:

http://www.hellionpowersystems.com/i...boost-resource

Thanks for this. Probably the most comprehensive Q+A I've seen on compound charges outside of Wikipedia.

[Jaden]

Originally Posted by the_one_mike

Can you cite any sources on this? Not that I don't believe you, I'd just like to read more because I don't fundamentally understand how a centrifugal blower could increase an inlet charge (at least efficiently enough to make it worth considering). You said that this is the most common use but I have had a hard time finding info on a setup done in this manner.

Also, Re: your p.s. ... I'm not sure what you are referring to as "primary." To me, the primary in the instance I described is still the twin screw, being as the turbo would be relaying a charge to it. The other way around and there is basically no point as you would still be dealing with turbo lag -- you would just be forcibly overspooling a turbo with a positive displacement charge. Maybe this is why you have suggested a large turbo so many times.

Sequential turbos a large one pulling from ambient feeding into the inlet of a smaller one is the most common. They are done in diesels all the time. The confusion on which is the primary and secondary comes from whether you're talking about how the turbos are powered versus the charge.


When I'm referring to the primary I'm talking about the FI system pulling from ambient i.e. ~14.7 psi for sea level.


The primary pulls from ambient and compresses that charge the charge then goes into the secondary at 14.7(or whatever ambient is) * whatever the pressure ratio is for the boost level it provides.


This is the important part. It now becomes a closed system. You can't get any more air than what is provided by the primary. So the flow rate of the secondary charge system doesn't matter, only the PR.


Now in a compound turbo, (Large turbo going into a smaller turbo) the smaller turbo is fed from the exhaust FIRST so that's where the confusion on what is the primary comes in. It's fed first because it will spool faster.


Controlling the boost on a compound turbo into turbo setup is paramount. It's easier with a s/c because the boost is finite for the s/c and you only control total boost output with the turbo.


You don't want a big turbo as the secondary because flow doesn't matter for the secondary, just p/r so you want it to spool as quickly as possible.


Here's why I think that a big s/c as the primary might work better.


Take a look at the compressor maps ogerf a big s/c like an Si trim Vortech


You'll notice that the airflow is broad as fuck. This means that if you use it as a primary even at low boost you have TONS of airflow. Since you're using a quick spooling turbo as the secondary, you can use higher boost at lower rpm and slightly lower boost at higher rpm and have a hugely broad torque curve, which is the whole point of a compound boost setup.


Jaden