dual 2.5 inch pipes and turbo

[66Sprint6]

Ok, I got the dual out header and since I was thinkin to do the turbo, I got them 2.5 inches all the way back to 3 inch tips. Would it be ok when I put the T04b on to run a 3 inch downpipe that splits to the 2.5 inch duals and Flowmaster 50s? I am going to be paying off this stupid tranny forever this summer but once its payed for the turbo gets spooooolin
Matt

 

[Anonymous]

I dont know what power output your planning on with your turbo but.
I made some enquiries about using a three inch on my 250 2V and I got the responce I expected (way too big). A three inch is huge maybe ok to use 2 two and a quarters. trouble is if its too big the exhaust doesnt extract properly it just floats around in there like its in outer space.
Cheers Tim

 

[JP]

For a turbo engine 3" into two 2.5" will be ok. The 3" will flow more than the combined 2.5" exhaust but this is good at the turbine outlet as it will help to break up the exhaust as it exits the turbine. With in reason it is beneficial to run large exhaust on a turbocharged system unless the exhaust is your boost regulator.
jp

 

[Anonymous]

For a turbo engine 3" into two 2.5" will be ok. The 3" will flow more than the combined 2.5" exhaust but this is good at the turbine outlet as it will help to break up the exhaust as it exits the turbine. With in reason it is beneficial to run large exhaust on a turbocharged system unless the exhaust is your boost regulator. jp

I agree that this setup will work fine - do it!

However, the old rule of thumb that a single 3" flows better than two 2.5" pipes doesn't hold true for turbos. The reason a single woks better for normally aspirated engines is that the 3" pipe can make better use of the exhaust pules from the engine to help scavenge the cylinders. However, a turbo breaks up the pulses to the point that they are useless. At that point it becomes strictly an issue of pipe size, and two 2.5" pipes have a total of nearly 10 square inches of corss sectional area, while a 3" pipe has by 7 suare inches.

 

[JP]

Thanks for the correction Stan. I was using the old plumbing rule of thumb for pipe sizing, square the diameter and compare. But seems I cant remember how to add.
3^2=9
2.5^2=6.25
6.25+6.25=12.5
jp

 

[Anonymous]

The area of a circle is pi*r^2, so...

...a 3" pipe has 3.14159*1.5*1.5= 7.07 square inches, and...

...two 2.5" pipes have 2(3.14159*1.25*1.25)= 9.82 square inches.

That's a 9.82/7.07= 1.39 increase...39% greater cross-sectional area.

 

[66Sprint6]

Well then, Im glad to hear all this. I didnt want to swap the exhaust AGAIN so Im glad I got the larger diam pipes. Besides, I like the 3 inch chrome tips
Matt

 

[BB6Mustang]

66Sprint6,
Ideally you want your exhaust to flow as much as possible after the turbo. You want the biggest possible pressure differential accross the turbo. The larger the pressure drop the faster the turbo will spool. The dual 2.5" system should be great, but you may want to consider a larger down pipe. A 3.5" pipe has almost the same cross-sectional area as the dual 2.5" (9.62 in² vs 9.82 in²). You can't really go too big on a turbo exhaust system.

 

[66Sprint6]

Oh yeah, definitely gonna get a large downpipe, at least 3". I didnt think about goin bigger, so 3.5" would be a good idea? Ill have to remember that
Matt

 

[Anonymous]

BB6Mustang is exactly right. In fact, the best exhaust for a turbo is...none!

A simple bell-mouth off the turbine section is what the Champ Cars use, and that's been shown countless times to be the best solution. That having been said, for max performance install the biggest pipe after the turbo that can be fitted into the space available. I have some diesel buds who are running 4" down pipes from their 1.6 turbo-diesel engines. The bigger thay've gone, the faster the car is.

 

[66Sprint6]

Awesome, thats good to hear! When it comes time to make my pipes, Ill mock up the turbo and see what the biggest downpipe I can fit is. Then Ill just have it split to the duals. Now that makes me wonder what sizeI can get away with. To bad I had this tranny problem or else I would have the money for the turbo already...dangit, lol, Im having a hard time putting it off!
Matt

 

[Anonymous]

One easy way to go from a big pipe to a small one is to invert a header collector reducer. These babies are cheap and come in a huge variety of sizes. I'm confident you'll have no trouble finding the right size when you're ready to connect the down pipe to the existing exhaust system.

 

[66Sprint6]

ok, now another totally different question about this turbo project. Should I think about maybe camming the motor? What cam should I use, if any at all?
Matt

 

[SuperMag]

What cam should I use, if any at all?

Others may call me crazy, even stupid, but I would use a camshaft...

 

[66Sprint6]

lol, I guess I shoulda said aftermarket, lol
Matt

 

[BB6Mustang]

Camshaft selection is much more of an art form than a science, but in general a good turbo cam has a high lobe separation (over 112° LSA), very mild duration (just a little more than the stock cam), and a high lift. There are a lot more factors involved, but this should point you in the right direction.

I don't remember you mentioning what engine you have , but Isky makes a 240/300 turbo cam you can check out: http://www.iskycams.com/engine_template ... gine_id=46
I don't know of any other companies that make Ford 6 turbo cams.

 

[66Sprint6]

Im runnin a 200 in a mustang
Matt

 

[BB6Mustang]

:rolflmao: I don't know how I missed that! You say exactly what engine you have twice in every post; once in your signature, once and in your avatar. I don't know what was wrong with me this morning.

A couple guys on this forum have turboed small sixes: import killer, Does10s (and maybe more that I don't remember). I would start by asking them what cams they have used.

 

[66Sprint6]

Yeah, Dan, importkiller, lives in murfreesboro and so do I (when Im not at school). I havnt gotten to see his car since he got the turbo running, but I saw it in development. I will talk to him more when it comes time to turbo cause he's gonna help me do it.
Matt