MPI piping sizes

[mstieg]

IC piping sizing...should it be based on turbo size or TB size? I'm getting Chad's MPI intake with a 75mm Ford TB. I currently have a small 16g which likely won't be enough to fill this intake optimally. I realize this and will go larger if need be once the MPI is up & running well.

 

From my understanding the pipes need not be any larger than the smallest/most restrictive part of the whole system. To do so would reduce spool time right? That restriction could be the IC flow rate, the turbo outlet size or the TB inlet size right? I may be wrong on the turbo outlet size? (ie. go a bit larger than that?)

 

For piping, what sizes are recommended?

[Evil_Betty]

I'm no expert at this, but if your just making it a street car, 2.25" would work fine. 2.50" piping may be better for you if you are upgrading to a larger turbo. I have seen a few 3" piping MPI setup's on here, but I think they were running high boost pressures.

 

I'm going with 2.25" piping on my MPI as 3" would be overkill on my setup. Check out the 300+ hp thread and see if there is any info on piping size from those guys ::

http://www.starquestclub.com/forums/viewtopic.php?t=8890

 

88whitestarion has 2.5" piping and made over 400hp, fyi.

 

-Justin

[Chad]

I'd do 2-1/4"if it were my car with those parts. I doubt any of the mitsu turbos can suprass the flow limits of 2-1/4".

 

2-1/2" is for large T-3's, mid sized t-4's, and 3" is for those running very high boost levels on huge turbos where every bit counts and lag doens't matter.

[DJpowerHaus]

I'd go for 2.5" in your case. I've personally seen 2.5" support 600hp. It is not going to be a limiting factor ever and its available everywhere and couplers are easier to find too (than 2.25").

[button]

I'd go for 2.5" in your case. I've personally seen 2.5" support 600hp. It is not going to be a limiting factor ever and its available everywhere and couplers are easier to find too (than 2.25").

+1

[substock]

i'm running 3", its overkill but i thought what the heck. i'm currently running a forced performance green turbo, but later might jump up bigger.

 

heres a pic of my setup.

http://i97.photobucket.com/albums/l225/substock/DSC01734.jpg

[ATCLen]

I like the 2.5".

[heefner]

I've got 2.5" in and 2.75" out. For your setup I wouldn't go over 2.5" The bigger you get the more difficult it becomes to fit everything in the engine bay and its just way over kill.

[Richie_Rich]

I'm not sure what I will run with my 60-1.

It has a 3" oulet.

 

My first thought was 2.75, but I don't know where I can find that as cheap as the stuff on eBay. I haven't looked lately though.

 

Another consideration is your intercooler.

If you are going to use a stock one, you are limited to the fittings available for it.

 

I wouldn't run 3" pipes down and reduce to 2.25 and then back to 3" out.

That would be foolish and waste unless you were going for bling when you first open the hood.

[Indiana]

If you buy one of those ebay generic kits and think you are ahead you aren't, I did that and in the end I threw all those crap clamps and non-reinforced connectors in the trash and ended up having to buy extra bends to make the pipes go where I wanted them to and not where the kit would allow so just buy the bends you NEED, then buy good T-BOLT clamps and good reinforced couplers in the color size and shape you want. One place doesn't have the best prices on all those parts you have to shop around

[mstieg]

Wow, this thread got some action today!

 

There's no way I'd even consider 3", as that's only for the huge 35psi boosting racers & such IMO. I'd figure that 2.5 or 2.25 would be okay based off the standard sizes I've been seeing on here over the years.

 

Currently I've got the stock 88 IC w/ full 2.25 pipes & OVCP. Of course the outlet piping would need to be swapped out & replaced for MPI. But if a bigger IC is worth it, that would be part of a full turbo to TB replace.

 

Paul says he's got the piping & IC done & ready to drop in, but I'm waiting to hear about sizes, etc. before considering anything further. I'm in no hurry to get this done or bought. It'll be a while as I slowly gather the bits & pieces as they and funds become available.

 

I stands to reason that smaller pipes should spool quicker than larger pipes at equal cfm output. Likewise, the larger ones would offer less resistance if there would be a bottlenecking issue in the pipes at all.

 

The optimal pipe sizing balance would depend on the turbo and IC combo. With a 75mm TB, that clearly won't be anywhere near restrictive and offers much more flow capacity than I'll hit, at least initially.

 

Rich, glad to hear you talking MPI. I wish you the best.

[heefner]

http://not2fast.wryday.com/gasflow/velocity.shtml

 

here is a link that calculates gas velocity in a tube given diameter and pressure. I'm not sure how much it will help but it does have a note at the bottom that suggest less than 300 ft/s air velocity is recomended at the T-body. At 650cfm and 2.5" pipe the mean velocity is 317. I suppose that's considering an ideal tube so it gives you a ball park. Or it will make you scratch your head some more :oops:

[Chad]

Those pipes I made for the IC Paul has are 2-1/2", the setup spooled very quickly and flowed well, I was running a 60-1 T-4 at 19 PSI with that setup.

 

If the path is short, you can run larger ID without adding to the lag. Many setups I've seen here are rather long, longer than setups I've been able to make, it just takes more effort (cutting/welding of the U-bends) to get the short paths to wrok. the setup I sold to Paul is under 4 1/2 feet long. to relate that to other setups, the stock setup (and most aftermarket setups) are about 7 feet long. The difference in lenght is so great, the larger pipes will actualy spool faster than a small diameter stock route because they have less volume.

[Richie_Rich]

Since we are on the subject of CFM and velocity, where did you come up with 650cfm?

 

Basic flow of a 2.6L at 7000rpm is about 324 cfm.

We have boost pressure so we are cramming more air in there.

How do you figure how much to raise the base?

I wouldn't expect it to double.

I guess I'm looking for ACFM

 

I did some quick searches and there is a formula, but the one I found had like 10 variables. I don't have time right now to figure out what each variable means and what value it has to approximate ACFM for our engine.

[eeaston]

2.5 is a good choice, it produces little restriction, and is pretty easy to route. Lag isn't really affected that much by the volume of your intake tract. It's 95% a function of the "size" of your turbine relative to the volume of exhaust produced by the engine, as well as the flow of the compressor relative to that of the turbine.

 

In addition, as Chad mentioned, if you mod the IC to exit on the driver's side and run the piping past the radiator on that side, you'll end up with similar volume to the stock setup with MUCH less restriction.

[mstieg]

Good stuff guys. Thanks for filling me in on those pipes Chad. It's crazy how Mistu designed their stock piping to run all the way across and back above the VC. I never understood why they'd add so much extra piping as well as cross over the hot part of the engine like that.

 

Rich, I'm not sure I can answer your question about cfm, but the stock 12a flows around 320cfm @ 15psi from what I remember. I believe my small 16g will flow about 500 or maybe 550cfm @ 15psi. Granted bigger will give more and at various boost levels. I'm not sure where the rpms play a part, but I do not ever plan to hit 7k on the tach, since I'm not an accomplished engine builder. :wink:

 

Will those 2.5 pipes of Pauls require a battery relocation? I assume they will, which is fine since I have an old speaker box & amp that's been dormant for years. I'll eventually build a new box for my subs that actually fits in the back of the Starion. :roll:

 

This thread is quite literally about "pipe dreams" No reason it can't be realized however.

[Chad]

yah, those pipes require battery relocation, and just a little bit of grinding of the radiator support.

[heefner]

Since we are on the subject of CFM and velocity, where did you come up with 650cfm?

 

Basic flow of a 2.6L at 7000rpm is about 324 cfm.

We have boost pressure so we are cramming more air in there.

How do you figure how much to raise the base?

I wouldn't expect it to double.

I guess I'm looking for ACFM

 

because thats roughly what my turbo flows at 15psi.

[ZPI28]

I like the 2.75" but it takes up alot of room, Ill have some more pictures of this hooked up to the stock TBI once I get it all back together. Like Indiana said I have spent more money on good couplers then what I paid for pipe kit and its cheap clamps/couplers. I couldnt have used this without the relocation of my battery to the rear of the car.

 

Steven

 

http://i62.photobucket.com/albums/h95/ZPI28/april001.jpg

[Truth]

2.5" will be more than sufficient for most applications.

[Vanishing Point]

I did some calcs awhile back and if I remember right 2" was enough for most anybody.

1.5 -1.75" caused pretty good restriction at higher RPMs. 2"the restriction dropped right off.

For a street drivable car (autocross) 2-2.25" would be ideal.

If all your looking for is max power then I cant see anything being to big. Of course thats if you are not shifting.

Probably the more important measure would be the sharpness and how many bends you build in. Short distance is best but not at the expense of the bends.

I built for torque so I used the stock piping (1.75"). Plenty of size for 6000rpm and 90% of the time I dont go past 5000rpm. My turbo spools fast and early so the smaller size works good for me. I dont need bigger piping because it would never get used.

If I had a turbo that spooled late(high rpms) then I would need bigger piping to help take advantage of that.

It all depends on what you want to use the car for. Pick the piping for the turbo you use.

 

Tony

[Austin88ESiR]

I am looking to go to MPI soon using the magna intake I have. If I wanted to keep the stock IC, do I need to replace the end tanks so the piping can exit on the battery side or can something be done with the existing set up? I prolly will go with 2.25 piping as I just want a good solid daily. I currently run a 17C.

[kfitts]

2.5 is all you will ever need. Good med. point

 

http://www.26liter.us/gallery/albums/userpics/10066/IM000615.JPG

[Richie_Rich]

If you look at the intercooler, it already exits on the battery side.

There is just a pipe that curls back to the passenger side.

 

Cut it off and have a stub piece welded back on.

 

*DMperformance has a MPI hard pipe kit.

I believe it comes with the stubs to mod your intercooler.

[Funky Phil]

If your gonna upgrade the pipes and put a bigger turbo in your better off going ahead and getting a better intercooler too. Ive got a 30x12x3 (wish I coulda found a 30x10 but oh well) Intercooler and run 2.5 pipes and I didnt have to do away with the batter. I removed the windshield washer resevior (never use it anyway) and beat down the lip on the frame rail and also opened up the little square opening behind the popup motor.

 

http://www.we-todd-did-racing.com/thumbs/large/348232_86475/6LDOHADGLBLRSO9.JPG

http://www.we-todd-did-racing.com/thumbs/large/348236_8b44a/PYL2T538H3IDNYQ.JPG

 

The 30x12 fills up the airdam wonderfully but requires cutting of the subframe. A 28 shouldnt need cutting.

http://www.we-todd-did-racing.com/thumbs/large/348229_3ad94/0JBQJ12KMR2LM9K.JPG