Turbo header theroy help

[HS30-H]

....note I've grouped 135 and 246 I'm not really sure what this will do I'm guessing increase scavenging but I really don't know all I know is that OS Giken grouped one header like this and from what I've seen no other manufacture has ever grouped a header like this.

 

.....But I'm still interested in the 135, 246 as to what it might do for me. I might have to email os giken and ask the man himself why he did it like that.

 

As I told you before when you asked me about this by PM, you are very likely to have mis-interpreted what you saw.

 

OSG never grouped their pipes that way on the TC24-B1. If you have a CLEAR picture of a 135, 246 then let's see it.

 

You have a thread rolling along here based on the presumption that you saw a 135, 246 grouping - but I think you are mistaken. Where's the evidence?

 

Alan T.

[turbobluestreak]

I read the 135 246 on an old pdf off of the osg website under the TC16. they changed the pdf sense then but I have a copy of the orginal one and thats what it said. so I assumed the info from them to be correct. I guess thats what I get for not really checking the picture.

 

 

 

 

 

tbs

[preith]

Ok, I found the pic:

 

 

I have no idea how well it works, who makes it, etc, but I sure like the way it looks. I'm at a loss when it comes to turbo theory, but just wanted contribute with a real world version.

[turbobluestreak]

thats hoovers header. Jeffps web pages said that he wanted around 2K for one of those.

 

 

 

 

tbs

[Brad-ManQ45]

Just as on a naturally aspirated engine, making a change to the exhaust system can sometimes mean making a change to the camshaft to take advantage of the change.

 

No-one in racing is in the habit of giving away specifics, but I could give you 3 scenarios:

 

The exhaust was flowing a lot better, so they changed the amount of duration on the exhuast side (shortened it), or they got to change the duration on the intake side, or BOTH.

 

The book did not mention specifics, just that that is what got them more power. They had already maxed the power with the log type of manifold and settled on the best cam for it.

 

You have to look at everything in/on the engine working as a WHOLE, not just a collection of good parts.

 

I can guarantee you that a Victor Jr. Intake and 780 cfm carb, 1.5" headers and a mild cam will run for crap. The same intake with 1.75" headers and a cam that makes peak power in the 6K range will be quite nice.

 

Or change the intake and keep the small headers and cam and go with a Performer intake and 600 cfm carb and you would have a very nice running package for a daily driven sedan.

[JustinOlson]

I'm no theoretician. My thinking would be velocity, velocity, velocity. The turbo exhaust header needs to move the exhaust gasses as fast as possible in as short a distance as practical. Tubing size should match port size, as few bends as space allows, equal lengths, shallow merge collector, etc. Everything after the turbo should be as big and open as possible.

I agree with John on what he has said. This is a very good basis for a quality manifold. Cylinder pairing based on firing order should seperate pulses as much as possible to keep individual cylinder pulses from interfering with eachother.

 

If you are running a divided turbine housing, you will want to pair cylinder 1,2,3 together and 4,5,6 together. This is vital to making a split scroll turbine housing work properly. On 2L race engines I've seen 1000rpm reduction in spoolup time by using a properly designed divided collector vs a common collector. Ideally you will want to use 2 wastegates as well to completely seperate each side of the turbine housing from one another.

 

Theres a good thread going on right now reading this here:

 

http://www.honda-tech.com/zerothread?id=1630241

 

Go read "Street Turbocharging" by Mark Warner. It will go into header fabrication a bit more.

 

Ideally, you will want to use an equal number of bends per runner. This balances the restriction across each cylinder. Priority number 2 is to keep the runners close to the same length. The average length of the runner will also effect the helmholtz frequency, and effects the torque peak. To read more about Helmholtz read this SAE article:

 

"Jameson, Renee T., and Hodgins, Patrick A., Improvement of the Torque Characteristics of a Small, High-Speed Engine Through the Design of Helmholtz-Tuned Manifolding, SAE Paper 900680, March 1990."

 

 

Regards,

Justin

[240zwannabe]

external wastegates will be 10x easier with a setup like that. it would also make it more efficient, nice design

 

edit: any thoughts of making em yourself and selling em? i'd be interested.

[thehelix112]

153 246 in a split pulse turbine housing will mean increased exhaust manifold pressure (in that side of the manifold). Now while you might think that this would lead to improved spooling due to an increased pressure differential, remember that the only reason a turbine spins is because the pressure is applying a FORCE to the wheel.

 

F = PA. Force = Pressure * Area.

 

So while you have increased pressure, you now have decreased area. So the question would be whether or not the interactions between the pulses converging in the pipes to create two larger bumps, as opposed to six smaller bumps, create a useful increase in force.

 

My gut says not really but I CBF thinking more about it right now.

 

Dave

[nat0_240_chevZ]

have seen the 153 624 pairing but only on a local engine with a slightly different firing order, hence probly why the diff.

 

you are chasing the 6 smaller hits on the turbine for better spoolup, as any irregular pulse interupts the smoothe acceleration of the turbine wheel, have a look at all the topend ex manifolds all aim for it, same with tuned length, or length compensation due to extra bends.

 

for an l-series having the 123 cyls into one commen collector and aswell as the 456 into another, gives best spread of pulses. then thos 2 colletors into1 or in the case of split/multi scrolls 1 into each scroll or have a flap that switches scrolls and is actuated by ex back pressure.

 

smooth bends into sudden merges/collection for pre turbo ex.

[73ZCAR]

Somewhat aged thread this.

 

No?

 

 

Mike.