3" to 3.5" or 4" or 5" dp how much gain?

[Race Jace]

I wonder why RJC will not dyno test his 5" pipe vs a 3" dp?

Because.... i am busy making parts and developing new products. I do not have time to conduct every concevable test that internet can throw at me. I will eventually dyno test it but as for now i have not. There is a thousand different combinations of cars out there and every one will gain a different amount depending on it's setup and how much HP it is making. Should i test every one?

So far the 5" Dp is worth 2mph over the Houston 3.5"er i had on there. the 3.5"er was worth 3mph over the 3"er. this is on my car in the 9.8 range. This difference would be bigger if My car made more HP.

You also can just look at simple fluid dynamics and pressure shape loss. You have to understand what is happening when the exhaust exits the turbo and obviously some people that posted here do not. Scavenge pulse out of the turbo? Pipe diameter affecting temperature? there is so much misinformation in this post i don't even know where to begin....

 

[VadersV6]

You also can just look at simple fluid dynamics and pressure shape loss. You have to understand what is happening when the exhaust exits the turbo and obviously some people that posted here do not. Scavenge pulse out of the turbo? Pipe diameter affecting temperature? there is so much misinformation in this post i don't even know where to begin....

There is no scavenge pulse out of the turbo. Whatever that is..There are resonant pulses in the piping itself, which help a great deal to scavenge the gases. Too much area and this pulse will slowed way down to the point of uselessness. When a pressure wave reaches a larger cross sectional area, it will reverse its sign (positive becomes negative, and negative becomes positive) and its direction. This is "reflection". The positive wave travelling towards the end of the pipe, and the negative wave travelling towards the turbine will propel exhaust gasses towards the end of the exhaust system. If the diameter of this pipe is 3 meters wide, the intensity of this pressure wave and reflection is very low. Pressure shape loss? Is this like nookular weapons?
Yes...pipe diameter affects temperature. Completely. Rapid expansion does that with gases. The expansion or contraction of a gas under pressure is adiabatic, meaning that there is a temperature change associated with the volume change. For an ideal gas, this relationship is expressed with PV=nRT. By performing mechanical work on a gas to change its volume, the temperature can be forced to change as well.
Now for coefficient of discharge. Say you have 2 downpipes that flow the same amount of air at the same pressure differential, but one of these pipes has a cross sectional area twice that of the other. The larger DP will have a coefficient of discharge that is half that of the smaller one.
Why? Velocity. Velocity is inversely proportional to an increase in cross sectional area. Doubling the cross sectional are will cut the velocity in half, and halving the cross sectional area will double the velocity.
You can probably see where Im going with all this..
Ive spent quite a few hours with my nose in the fluids books and learned quite a bit. I applied my knowledge to intake manifold design and managed to pull something off no one had been able to do in the mustang world. I beat the best in the business by far, and did something people said was impossible. Ill be getting a mention in 5.0 magazine next month, even though I quit doing this stuff 2 years ago. While I'm wrong about things just as often as anyone, I refuse to accept conventional wisdom alot of the time cause that leads to nothing but closed doors, and its pretty boring too.

 

[norbs]

Well i guess that the 5" pipe is worth .5 in et over a 3" pipe then all your calculations are not what is happening in the real world. This translates into over 60 hp at the wheels? I'd like to see your explanation now???

 

[SPOOLN]

Is this a case where bigger is better? Hell, first you have to see if the turbine scroll outlet is your biggest resistance. At what point do you need a bigger DP, the 3 inch THDP has been in the 8s so would the 5 inch put him in the 6s? If he still had his car.

 

[norbs]

Well i guess i will be ordering all the bends and start fabricating a 4" elbow, then neck it down to 3.5" the rest of the way.

 

[Race Jace]

Well i guess i will be ordering all the bends and start fabricating a 4" elbow, then neck it down to 3.5" the rest of the way.

4" ???? no, no no. you need a heated 2" to keep the velocity up...

yes, you are very well versed in fluid dynamics, it is your application and engine mechanics understanding that is lacking. That is where you are getting confused.

 

[VadersV6]

4" ???? no, no no. you need a heated 2" to keep the velocity up...

yes, you are very well versed in fluid dynamics, it is your application and engine mechanics understanding that is lacking. That is where you are getting confused.

Yeah, I guess the first model engine I built when I was 5, or the 23 years working on engines or the 7 years I spent as an engine machinist/engine builder for JMS racing engines that led me in the wrong direction. Porting an endless amount of intakes and heads, machining and building thousands and thousands of cylinder heads and hundreds upon hundreds of blocks of all types makes and sizes..... From making 500-600hp out of a turbocharged 1.8 liter honda motor back in the beginning of the import scene, to 1500hp boat motors to Winston West to Top Sportsman to Super Stock drag classes, and on and on and on. Maybe you've seen engine buildups and dyno testing at JMS in Car Craft, Hot Rod, Engine Masters, etc. Learning from people who have set records in almost every racing circuit for the past 50 years didnt hurt. Many of these guys were setting records before I was even born. I just never learned how to apply the knowledge or even learned about engine mechanics....
Just giving you a hard time. While everything I wrote is true, I still dont know a great deal (you can spend a lifetime working on engines and still not know it all) and I respect what youve done with your company and with your products. I just wont be on the order list for a 5" DP any time soon. :wink:

 

[chevyII]

Give old kenny dutt. a call and see what he has to say about plumbing after the turbo. Might change some minds.

 

[chevyII]

Spintech has stainless reducers in a smoth transitions

 

[VadersV6]

I second the idea to call duttweiler.

 

[norbs]

He doesn't asnwer the phone usually, has messages relayed through his recptionist.

 

[John Wilde]

He doesn't asnwer the phone usually, has messages relayed through his recptionist.

Be careful with the wording that is his wife Margie...

 

[norbs]

I wasn't sure, i;m sure someone down there could call for us, Who would want to talk to a crazy Canadian anyway?

 

[John Wilde]

I wasn't sure, i;m sure someone down there could call for us, Who would want to talk to a crazy Canadian anyway?

You are I good guy and I do not hold your nationality against you.
I need to call this week, I will try and remember to ask.

 

[SPEEDSTAR]

Interesting ,and inspiring thread , knowing I"ll be picking up my new Miller Syncrowave 180 amp Tig welder tommorro, having it delivered to work might just fab up a 3.5 or 4" dp. Jeff , oh yea good link for stainless tubing,ie: a 3.5 for 31.86

 

[norbs]

The radius on the 90's from that link are not very tight I have to source somewhere else. You will roughly need about 1 amp per .001 of wall thickness, maybe a bit less, have fun

 

[Race Jace]

Give old kenny dutt. a call and see what he has to say about plumbing after the turbo. Might change some minds.

Or you could read a book on turbocharging... like the one from Hugh Macinnes.
even VadersV6 theorys would change. lol

VadersV6, from reading your posts I just don't believe your experience. For all i know you are some 15 year old kid that does not even have a licence. that is the beauty of the internet...

I really would like to disect and clarify this post but i just don't have time to do it. It is a busy time for me right now.

 

[Garycar]

Jason,

Unfortunately my turbo exhaust outlet to the downpipe is the round 4 bolt style. Will you be producing one for those of us with this type flange? I would order one today if you had one. And thanks for the excellant products that you manufacture for the Buick community.

 

[VadersV6]

VadersV6, from reading your posts I just don't believe your experience. For all i know you are some 15 year old kid that does not even have a licence. that is the beauty of the internet...

The truly funny thing is, how you still havent clarified anything. Ive made statements (so have others) and asked questions and you find some way to slip and slide around them. You have a vested interest to protect, and you wont dare tell anyone that they may not need your oscar the grouch trash can sized downpipe on their 14 second TR. My experience is valid, and true. I have machined and built thousands of engines. I have done an endless amount of research and testing of ideas. Some were bogus, some were legit. If you're hearing things you either dont understand, or refuse to believe because the boundaries of reality have already been boxed up for you, then thats not my fault. So as you said, "what happens to the exhaust flow when it comes out of the turbo"? Tell us. Tell all the good people out there why they need your Boeing 747 landing gear sized downpipe?
I commented on the effort that must have gone into it. I stood up and attested to the probable machining time it would take to make that adapter (Im a CNC programmer and machinist and automation integrator for the past 8 years). I tried to say how many hours it would take, and that the cost of the product is easily justified. I said you make great products over and over. Then you suggest Im a zit faced kid jacking off behind a computer screen who knows nothing. Real Classy.

 

[chevyII]

I'll save you all the trouble of of calling Kenny and wasting his time. He did a seminar at SEMA a few years back and to make a long story short you should have absolutley no back pressue beyond the turbo period. What does that equate to on our small engines I dont know. Maybe need a pressure gauge in the DP to check. I think the 90 bend right out of the turbo cant be optimal though. I'm going to turn my turbo 90 degrees on the header and run all 4" on my stage 2.