Short Charge Tube Good or Bad?

[Fack]

As stated there is no optimum plenum volume or simple equation that can be used to solve this problem. This is because all situations are different and the systems AS A WHOLE function differently. Charge tube volume and plenum volume are both considered as part of total available air supply. This is important when dealing with a pre boost condition as this is the "reservoir" of air your engine has to draw air from before the turbo is building pressure. That being said, if you design a larger plenum with a smaller charge tube that is able to meet an engines air requirement I would think you are better off because of the pressure losses that occur in the charge tube itself. Our objective is to supply a volume of air at a certain pressure, so anytime we experience pressure losses to our system (charge tube) we lose overall efficiency in our system. Again, this is only dealing with the intake side of things. As Kelsey stated in most cases in order to move our turbo closer to the intake we have to lengthen our exhaust. I was talking to a guy a few months back about a busa motor he had built to compete on a dyno in Florida. He said by shortening the header 5 inches he was able to gain substantial (can't remember the number but I want to say it was around 60 horse) power. This was largely impart due to the heat lost in the longer header. From this a person can conclude that there are many tradeoffs when designing a turbo SYSTEM and many factors to consider when designing a system to meet certain specific needs. A system designed for huge power is not necessarily the same as a system designed for good throttle response and drivability. I believe that finding the perfect balance is what we're all after and Shain's turbo is a step in a new direction for most of us. Keep up the good work and good thread!

-Fack

 

[JSCC]

As stated there is no optimum plenum volume or simple equation that can be used to solve this problem. This is because all situations are different and the systems AS A WHOLE function differently. Charge tube volume and plenum volume are both considered as part of total available air supply. This is important when dealing with a pre boost condition as this is the "reservoir" of air your engine has to draw air from before the turbo is building pressure. That being said, if you design a larger plenum with a smaller charge tube that is able to meet an engines air requirement I would think you are better off because of the pressure losses that occur in the charge tube itself. Our objective is to supply a volume of air at a certain pressure, so anytime we experience pressure losses to our system (charge tube) we lose overall efficiency in our system. Again, this is only dealing with the intake side of things. As Kelsey stated in most cases in order to move our turbo closer to the intake we have to lengthen our exhaust. I was talking to a guy a few months back about a busa motor he had built to compete on a dyno in Florida. He said by shortening the header 5 inches he was able to gain substantial (can't remember the number but I want to say it was around 60 horse) power. This was largely impart due to the heat lost in the longer header. From this a person can conclude that there are many tradeoffs when designing a turbo SYSTEM and many factors to consider when designing a system to meet certain specific needs. A system designed for huge power is not necessarily the same as a system designed for good throttle response and drivability. I believe that finding the perfect balance is what we're all after and Shain's turbo is a step in a new direction for most of us. Keep up the good work and good thread!

-Fack

Nice post Fack. That deserved you having full green.

 

[Lucky Lyle]

The stinger on this sled is still shorter than the one that was on the slp set up that was on the sled to start with. there is no issue with throttle responce or compressor surge.

 

[Scott]

This is a good thread.
Keep it going.

Jr, I couldn't help but thinking the whole time I read your post...."Which came first, the chicken or the egg?"

LOL

Thanks for the replies,
The general consensus seems to be the smaller the intake (charge tube/air box) volume between the turbo and the engine the faster the spool time. It would appear that the order of operations is disregarded, and the focus is shifted primarily to the intake or charge tube area.

Everyone knows that a turbo is powered by exhaust energy. So it would stand to reason that the volume between the engine exhaust and the turbo would be more critical in regards to spool time than the intake. But the exhaust is still not the first component in the order of operation. First the engine has to create this exhaust energy.

In order for the engine to create the exhaust energy needed to power the turbo, it first has to take air in, digest it, and finally exhaust it. If the intake air space between the engine, and the turbo is not adequate, then the engine will have to pull air through the restriction of a stagnant turbo, before creating enough exhaust energy to propel the turbo henceforth causing classic “turbo lag”.

This line of thinking completely debunks the “smaller the charge air space the better” theory.

Here is one example of real world R&D, to back this up. We mounted a turbo to an engine in such a configuration that the compressor housing mounted almost directly to the throttle body, performance was minimal. Without relocating the turbo, we then indexed (rotated) the turbo compressor housing to accommodate a charge tube that circled the entire turbo before entering the throttle body, this charge tube was approximately 20” in length, and was the only change made to the turbo configuration, throttle response, and performance was increased a hundred fold.

The next thing to consider in charge tube design would be would be charge air velocity. What effects does the size, and shape of a tube have on charge air velocity, and what effect does charge air velocity have on engine performance?

Junior

 

[m8magicandmystery]

like must applications that like to put out...generally they want the tube to be long,slightly upward bend and as thick as clearances allow...and hard on both ends

 

[hatchers]

Very good topic,

All I know is a standard twisted kit has the least amount of bog/lag over any turbo 2 stoke sled I have ever ridden, the twisted pump M1000 feels like a stronger stock sled, I know this sounds crazy but you will not notice the turbo arm stretch…..is this due to setup? Sure it is

Now on the topic of volume in-between the compressor and engine. I’m sure saved by grace would not come here and post a lie as he seems to be a no BS kinda dude, so it must be true, in his application a larger volume of charge space was better…..but that’s all it is, one single application that is from many variables.

The fact remains, building a optimal turbo kit with a smaller charge tube area is what Shane has done with his twisted kit. People are making a science fair out of stuff they don’t understand….understand I do this stuff on a much larger scale for a world leading manufacture in the field service side…..so ive seen some stuff and work with many customers who they know, but have no clue. Hate to toot my own horn and sound like a big shot….but ive made sexy time with many of Hollywood’s elite and smoked the devils lettuce with brad and Angelina…..and let me tell you, brad gets da bomb arse chit yo!!!!xdcx

Also, I think many are reading this is getting even more confused about what kit to buy….get lucky and find some folks who have one for the four major kits (BD/Twisted/OVS/Cutlers) and decide for yourself…that’s what I did and must say I like all that I have ridden, some are better for hill humping and others better for boon docking.

Keepin It Simple fun Fact:
- the exhaust side turbine wheel needs to spool up and push the intake compressor side, exhaust is the driven and intake is the driven…consider both sizes for both wheels and engine size, pipe size….yada yada yada

 

[mountainhorse]

but ive made sexy time with many of Hollywood’s elite and smoked the devils lettuce with brad and Angelina…..and let me tell you, brad gets da bomb arse chit yo!!!

Hatchers... are you sure you aren't smokin that stuff now???

ROLMFAO!!

Are you a field service tech for MTU?

 

[Going West]

^^^^ x2

 

[sunbather1969]

tech

im a tech for man on the polar tanker fleet doesnt make a diff you actually have to have *** time on a machine otherwise its just hearsay ....i still don't know where im going with a turbo decision why doesn't anyone have literature or do they i'd like to know what i get for 7 gs

 

[product tester]

im a tech for man on the polar tanker fleet doesnt make a diff you actually have to have *** time on a machine otherwise its just hearsay ....i still don't know where im going with a turbo decision why doesn't anyone have literature or do they i'd like to know what i get for 7 gs

On our web store there are parts lists of what you get with each kit.
www.Twistedturbos.com have not put the poo on there yet.
Jr there are reasons why when you tested short charge tube you didnt get what you were looking for, one of them could be my 50mm bov thats on the air box and is wide open at idle.

 

[savedbygrace]

On our web store there are parts lists of what you get with each kit.
www.Twistedturbos.com have not put the poo on there yet.
Jr there are reasons why when you tested short charge tube you didnt get what you were looking for, one of them could be my 50mm bov thats on the air box and is wide open at idle.

OK PT you picked the next topic.

Why don’t you explain to everyone here how that works?

Let’s see if we can get though this next thread without plugging any particular product.

Junior

http://www.snowest.com/forum/showthread.php?p=1697897#post1697897

 

[product tester]

OK PT you picked the next topic.

Why don’t you explain to everyone here how that works?

Let’s see if we can get though this next thread without plugging any particular product.

Junior

http://www.snowest.com/forum/showthread.php?p=1697897#post1697897

Jr you are trying to turn this bad lets not go there if ya want to know why mine works Im not willing to give that up yet as I have spent alot of time and money on this kit I could have put this out when I started to sell cats but I was not happy with the testing or performance. this didnt just happen over night and was not just built with no back ground info, or testing.
I have to pat ya on the back for trying.

 

[savedbygrace]

What's the point?

I was asked by consumers to post some tech info, in an attempt to clear up some common misguiding, myths and concepts about turbo operation, and theory. That is the point of these threads, plain and simple.

These threads are for general information only. I am not interested in bashing any particular product or manufacturer, that is why I have refrained from commenting on questions directed at any individual branded product. If anyone wants to participate in this with any turbo knowledge, concepts, theories, experiences, or questions you are more than welcome.

Junior

 

[gus bohne]

Though this is a decent thread it is quickly falling..
wait till the snow is on the ground and ALL the answers, theories and computer models will work themselves out.

We should all realize that no one os breaking any new ground, turbos have been in use for decades. We are all really just monkey see monkey do ..

Box designs that spend days on the flow bench are nice, pressure differentials of even an inch or less will destroy your best design. Injected engines are much less susecptible as bowl signal is moot point.

All two strokes have a gulp factor, to small a box and poor drivability is your hurdle. why?
Reversion, its that ***** we have to live with. as long as we have that little reverberation and regurgitation of fuel charge we are gonna need a way to disperse and dampen its amplitude.

the rotary valve we thought would be a super turbo base as we thought we could better deal with this ......not soo..more issues ..


gotta see how big the box is on the sealevel turbos.. behemouth ''

with a cpi box on a rev 800 I use really small pilots to combat the reversion issue, using stock double V stack reed cages makes it even worse.

reed angle, tensioning and flow rate..

I look forward to the field results and will be watching to see the twisted set up polaris hit the snowcross tracks with that wicked cool rollcage/turbo hanger.!!!!

mounted for battle ! love it.

Gus