Got a question...

What's the story on runner diameter for a equal length tube tuned turbo header? I did some quicky calcs and the perimeter of the ports suggest a 1.5-1.6 inside diameter pipe for matching size (if you squish it down to match the port).

But what's the ideal diameter in general?

Is there a magic "manifold internal volume" to stay under? a max diameter for high velocity flow? a minimum for avoiding choked flow?

what about length? short is better, but how long is too long?

grassy ***,

Matt

 

Generally what I have seen and use is 1.5" Sch. 10/40 tubing which is approx 1.5" id and 1.9" od. The best flowing manifold are usually a bit longer with low divergent angles into the collector.
-Michael-

 

hmm ok.

I usually see the four pipes merge at the collector by being mitered together... like a four leaf clover.

Mcmaster has some neat offset transitions that might be interesting.... what's the hole size on the T2 flange?

 

Right, I was referring to the angle at which they are mitered being a smaller angle.
-Michael-

 

Here's what I was talking about...



they have them in
1 1/4" x 1/2"
1 1/4" x 3/4"
1 1/4" x 1"
1 1/2" x 1/2"
1 1/2" x 3/4"
1 1/2" x 1"
1 1/2" x 1 1/4"

sizes. they also have center-center transitions. maybe if you wanted to use a flattened tube at the port and downsize to a smaller runner size.

 

cha-ching.

 

why, because they're 30 bucks each?

 

Yep. $30 is gas for 3 days.

I believe 1.5" sch.40 pipe fits pretty well on a T2 inlet flange. I just did this a few weeks ago and can check what size pipe it is later today. I did have to use a torch and massage it a little.

 

Interestingly enough, gas for 3 days is what you get after eating $30 worth of Taco Bell food.

Why do people relate everything to the price of gas nowadays? It's like those fast-food commercials were people relate everything to the price of frostys or jr. bacon cheeseburgers or whatever. $1 million!? That's like a million junior cheeseburgers!

Sorry to get sidetracked

 

You're talking about using four of those to make a collector?

$30 in 3 days? That's a lot of driving... or a lot of full throttle driving!
I think the gas vs. whatever is just significant of how much people drive. I've driven less than 1000 miles since October.

 

I don't even use miles as a measurement of distance anymore...I just use dollars-worth-of gallons.

"How many miles do you have on your car?"

"About $12,500 worth of gas."

 

For some reason when he said gas... I thought welding gas. Heh

 

ok thread hijackers. I dont give a rats *** about gas prices. If I did I'd drive a turbo prius.

I'm not actually *making* this manifold yet, I'm just pickin your brains. I saw those offset flares on McMaster.com and thought they'd make a nice smooth collector.

I'm tempted to draw some stuff up in pro/e and verify centerline distances are within a percent or two for my own edification.

I just thought I'd get the DIY expert opinion first.

 

Ohh making your manifold in pro E or the like is a great idea. I did that with my twinturbo manifold and created full scale templates for all the transitions. It made life a lot easier.

You do have a good idea, using one of the larger transitions maybe 2.5 - 1.5 may make the collector fab work a lot easier. I would consider it especially if you are using a MIG welder so you can fill in any gaps.

One area I have used transitions is on my downpipe. Burns Stainless has nice high quality stainless transitions in regular exhaust pipe thickness; I used a 3" to 2.5" on my old Downpipe.

Back to the original hijack: I drive just over 60 miles each direction to work, which I think is average for this area. The guy I carpool with drives from center city Philadelphia to the Jersey shore each day.

 

modeling els as I type

I didn't think of a large 4-into-1 sized transition... but wouldn't that be much harder to deal with than just making up a flat-walled funnel shape? four circles dont really fit well in a big circle (or a square for that matter).

I did the downpipe transition too. My new DP will have a 2.25-3 transition since the 2876 output is 2.25 at the flange.

that's a long drive. I used to do 45 miles each way around silicon valley... long commute and most expensive gas around sucked... but I carpooled--more for wear and tear on the miata than anything else.

 

Found this secret link of flange sizes. neat.

http://www.jgstools.com/turbo/tif.html

 

Four circles do fit well if your cut them right.
http://www.homemadeturbo.com/forum/i...2899#msg352899
That link has a good write up on making your own collector.
Beware, it's in the Fabrication/**** Subforum.

 

fabrication/****. heh.

that's how my manifold's built. but damn, spend a little on a TIG welder and you get nice welds after some practice.

 

Flipside has head flanges available that have the recess machined already for the 1.5" Sch 40.

 

could flipside have anymore media on their main page? geezes.