supercharged turbo

[SUPERVAN]

As far as the VW motor having one IC that may be true and doing a supercharger into a turbo I don't know, I haven't looked into it that closely. I do know that they do disenguage the SC though, I would think they would bypass it as well when it disenguages as not to be a restriction on the intake track. Actually frostburner, All the twin charging setups I've seen on the internet use a roots or vane style blower and they do compound boost. Now a centripedal supercharger I'm not sure about.

[yarcli52]

They do. They have an alternate section of plumbing with a "one way" valve. I'm in the process of this setup myself, only on a hell of a bigger scale.

[frostburner]

Here is one of the diagrams for a twincharge setup with bypass valve and disengaging clutch. also to get a proper compound setup would be to use turbos as it recompresses the air internally. a roots blower rams air and creates pressure by the stacking affect so its not as efficient as turbo compounding if thats what your shooting for. intake manifold design and also an exhaust system play an important roll in how much boost you create as well by limiting or creating more of an air charge with the blower. taking the turbo knowlegde i learned over the years and the supercharging knowledge ive learned over the course of almost 2 years designing supercharger systems for cars and trucks i believe the way the vw went is a really good setup to follow

well for some reaso the image keeps dissapearing everytiem i try to post it lol.. damn free image hosting.
just copy and paste into your browser
http://images6.theimagehosting.com/DNX051024N699A.jpg

[yarcli52]

My question on this topic is what type of CPU is going to manage twincharged engines?

[The Pope]

Quote:

Originally Posted by yarcli52 My question on this topic is what type of CPU is going to manage twincharged engines?

same as a regular turbo computer. You need a boost fuel and spark curve, which turbo computers have

[The Pope]

Quote:

Originally Posted by frostburner http://images6.theimagehosting.com/DNX051024N699A.jpg

now that system is a good idea The first time the bypass sticks or the compressor doesn't shut down or the compressor doesn't clutch in you have a problem. Shoving air through a slower moving compressor sucks, nice restriction to heat the air up.

As a simple way to describe it you can use math to show the idea of the right way to do it. Air is weight, compress it and you have more weight with the same mass.

So while the turbo is in lag the SC turns 1 lb at 1 cubic inch into 2 lbs at 1 cubic inch of mass. Then the turbo kicks in and sends compressed air to the SC. The turbo sends in 4 lbs at 1 cubic inch and the SC now compress's 4 lbs instead of 1 lb. Just as it doubles it at 1 lb it doubles it at 4 lbs to 8 lbs at 1 cubic inch.

Wah the numbers are not exact but they are relitive to what physically is going on. Have the air coming from a big IC out of the turbo and the SC is compressing air that is already compressed and cold for even more density. Now even if the belt breaks on the blower it'll freewind and the engine is OK. The VW setup will run like a duck taped air filter when the bypass is shut and the blow doesn't engauge. Nothing like adding a ton of compications and raising your chance of error.

[The Pope]

I should add the reason it works well is that working together neither the SC or the turbo have to work that hard to make huge PSI. The air bashing that heat air for the amount of boost you get.

[frostburner]

Quote:

Originally Posted by The Pope now that system is a good idea The first time the bypass sticks or the compressor doesn't shut down or the compressor doesn't clutch in you have a problem. Shoving air through a slower moving compressor sucks, nice restriction to heat the air up. .

im pretty sure vw tested the setup extensivly before putting this in their 1.4 and as long as its designed correctly you wont have issues. you should let thier engineers know the right way to do it. oh and im pretty sure a roots style blower does not internally compress air, its lobes are meant to pull air in and whip it out so its not truly compounding as turbos would as in diesal applications.

[cook]

Instead of doing the bypass valve and clutch system cant you run a Y out of blower having one pipe feed the turbo inlet where you normally have the air cleaner and one into another Y that feeds the Throttle body with a D-valve near the T/B and one near the exit of the blower , then have another pipe from the turbo feed the other part of the Y into the throttle body. This way you would have the blower operating at low rpm and as soon as the turbo spooled up and surpased the blowers PSI would close off the D-valves and the supercharger would end up feeding the turbo? Just a thought. Or could you get away with no D-valves and just run it open and have them both feed the T/B all of the time??

[SUPERVAN]

Quote:

Originally Posted by frostburner oh and im pretty sure a roots style blower does not internally compress air, its lobes are meant to pull air in and whip it out so its not truly compounding as turbos would as in diesal applications.

If a roots style blower causes an engine to see boost and the air its compressing is already pressuriesd then it will compound pressures. and when I say pressures I don't mean 7.5psi x 7.5psi =56.25psi. that would be rediculus. I mean that 7psi from a turbo =1.5 bar atmospheric pressure and 7.5 from a supercharger (0psi=1bar) that 1.5bar x 1.5 bar=2.25 bar 2.25 bar=33psi 33psi-14.7 psi(normal atmospheric pressure)=18.3 psi. bottom line if your compressing compressed air it will compress further.

[frostburner]

its just not as efficient as compounding with turbos, yea itll work in that sense but turbos are better for compounding

[SUPERVAN]

Quote:

Originally Posted by frostburner its just not as efficient as compounding with turbos, yea itll work in that sense but turbos are better for compounding

Of course they are, turbos are just more effiecient in general, but you still have to spool both.

[frostburner]

thats why i said they arent as efficient, lol you just repeated what i said

[yarcli52]

Can our common blocks handle all of this pressure? If so, to what limits and boost can you run twincharged systems?

[tkelly27]

You're worried about the boost pressure cracking the block? That's irrelevant compared to the pressures that go on once the clyinder has fired. Are you worried about the power the engine is producing cracking the block? Stephane is up to 1000hp with a few modifications to the block, you won't be that high with a twincharged system. Your intake tubing however...

You are right that the roots blower throws the air into the intake manifold, I'm not sure how a pressure differential would change this though. The turbo works on the same principle, but instead of the air being slowed down when it hits something in the intake manifold, it's allowed to expand gradually in the compressor housing, slowing it down and increasing pressure.

Compound charging FTL! Unless it's a diesel : D