im boosting a d-series using an mk3 ct26....i was wondering if 3" was to large to use for charge pipes ....and is 2" to small ?? any suggestions or ideas would be great.... id use 2.5" but i dont have access to it so if you had to pick which would be betterthe 3" or the 2"

 

Use your head how much power do you want to make? 2in is good for 300hp (thats at the engine).. I would use 2in if its a stock engine.

 

Try this place for the 2 1/2 inch its pretty cheap http://store.racing-solutions.org/

 

There have been a lot of posts about this, and from what Ive read, nothing has really ever come out of them. The most Ive been able to gleen from multipule posts is that there are many things that play a part in what size you need for charge piping. Generally, 2.25in piping will do just fine for most moderately boosted stock internals Honda engines. 2.5in is good for over 500whp.

Blaze

 

thanx for the info.... the only real info ive gathered from the search is that the larger the pipeing the more lag the setup will have....and since ill be boosting on a stock block im gonna assume that the 2-2.25" will be perfect for my setup.... thanx for all the helpful info guys....

 

Larger intercooler pipe diameter does not create turbo lag (at least enought to be noticable). Also, match the piping to the throttle body. No reason to go any bigger. 2"-2.25" will be fine for your setup.

 

actually i was reading some calculations another member had come up with in a previous thread i found in the search.....and the explanation was that since ur using larger charge pipes it takes long to build up pressure within them.....since a 2" holds alot less volume then a 3" thus creating some form of lag.......this is how i took in the information perhaps im wrong perhaps its only a theory anyonce care to elaborate on this ?

 

I did some quick number crunching and with the aid of THIS site I figured out the airspeed of your intake air. It would help if I knew the actual CFM of your setup, but I just used 700 CFM.
The area of a 2.5" pipe is 4.90625 square inches
The area of a 3.0" pipe is 7.065 square inches

That online site uses length x width.

The equivalent L x W for a 2.5" pipe is 2.453125 x 2
The equivalent L x W for a 3.0" pipe is 3.5325 x 2

Now input 700 cfm and 2.453125 for the length and 2 for the width. Select speed as MPH. The speed for your intake air with a 2.5" pipe is 233 MPH or 0.31 MACH

speed calculator

Now input 700 cfm and 3.5325 for length and 2 for width. Speed will still be in MPH and for a 3" pipe the speed comes out to 162 MPH or 0.22 MACH.

If you stick with the same overall setup and just go from a 2.5" to a 3" pipie you see that there is a 40 MPH decrease in velocity. That's assuming that you are flowing 700cfm, but you get the general idea. That lost velocity translates into increased lag. Because when you shift it takes longer for the 3" pipe to pressurize because the air inside is only moving 162 MPH, vs 233 MPH for a 2.5" pipe.

this was psoted by blue shadow here on h-t

 

I don't know who tought you how to add and subtrace, but 233-162 is 71mph

Now you say, 71mph decrease in air speeds... This might sound a bit shocking! OMG OMG 71mph decrease of air velocitys over a hold 10ft of charge piping. (no one here has 10ft of charge piping, but i just used that number for giggles, usually 5-7 feet depending on the setup.)

Anyways,

162mph means the air is traveling @ ~238fps(feet per second)

233mph means the air is traveling @ ~343fps.

So...How long does it take some little air particals traveling at 162mph to travel 10Ft of tubing? A whole 0.042 seconds.(roughly)

And....for the little air particals traveling @ 233mph.... 0.0291 seconds.


So that means... It is going to take 0.0129 more seconds for 3" vs. 2.5" for the air to travel the pipe.

------------------------
This is simply based on a straight piece of tubing. If you really want to get into it, we can do it based on the restrictions a 2.5" pipe will create the tighter, and smaller bends required slowing the air down vs. the more free flowing 3".
------------------------

Now lets think about this a bit more...the 3" will support more power by moving more CFMs, with barely ANY lag. IMO, .0129 seconds difference isn't going to change anything on your 15 second car.


Don't think I'm trying to bash you in any way. I just don't want to see a bunch of people on here saying 3" isn't worth it , it slows down the velocity by 71mph, blah , Lag , lag lag, blah blah blah.

My suggestion...unless you're going to make 500whp+ stick with 2.5". Why? chances are it's the same size of your intercooler end tanks along with the size of the throttle body. You'll need one expander that comes off the turbo and that shouldn't be a problem. Not to mention 2" & 2.25" charge piping looks retarded under a hood.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by simike &raquo;</TD></TR><TR><TD CLASS="quote">Larger intercooler pipe diameter does not create turbo lag (at least enought to be noticable). Also, match the piping to the throttle body. No reason to go any bigger. 2"-2.25" will be fine for your setup. </TD></TR></TABLE> Of course it creates lag. 2inch will be fine I make 255whp on 2inch piping stock dseries.

 

if you would kindly re -reas my post properly ud see that the math was not done by me ....but by a fellow h-t member and that was what i assume his theory is on larger pipeing creating lag......


my setup is a stock block boosted D and i am hopeing for at least 250 whp .....turbozxi thanx for the info but is 300 whp alos doable with the 2" ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The Stance &raquo;</TD></TR><TR><TD CLASS="quote">if you would kindly re -reas my post properly ud see that the math was not done by me ....but by a fellow h-t member and that was what i assume his theory is on larger pipeing creating lag......


my setup is a stock block boosted D and i am hopeing for at least 250 whp .....turbozxi thanx for the info but is 300 whp alos doable with the 2" ?</TD></TR></TABLE> No I would go for 2.25in for 300whp, you going with rods and pistons then I assume?

 

Pmed.

 

nope no rods or pistons.......im actually going to try and make 300 whp on a stock internal d16a6....the only modification motor wise will be arp head studs......and a p30 i/m modified to fit the d16....

 

Your actual results may vary (ie when you add an IC) so just use my numbers as sort of a bench mark to compare different piping sizes. One thing you guys will notice is that none of the velocities goes above 304 MPH or 0.4 mach. According to Corky Bell, Maximum Boost pg 61, 304 MPH or 0.4 mach is the point at which airflow meets increased resistance (drag) and flow losses are experienced.

Anyways here are the numbers I came up with. The velocities are in miles per hour and mach, and the flow rates are in cfm. Measurements for the piping are in inches.

0.4 mach = 304 MPH

2" piping
1.57 x 2 = 3.14 sq in
300 cfm = 156 mph = 0.20 mach
400 cfm = 208 mph = 0.27 mach
500 cfm = 261 mph = 0.34 mach
585 cfm max = 304 mph = 0.40 mach


2.25" piping
3.9740625 sq in = 1.98703125 x 2
300 cfm = 123 mph = 0.16 mach
400 cfm = 164 mph = 0.21 mach
500 cfm = 205 mph = 0.26 mach
600 cfm = 247 mph = 0.32 mach
700 cfm = 288 mph = 0.37 mach
740 cfm max = 304 mph = 0.40 mach


2.5" piping
4.90625 sq in = 2.453125 x 2
300 cfm = 100 mph = 0.13 mach
400 cfm = 133 mph = 0.17 mach
500 cfm = 166 mph = 0.21 mach
600 cfm = 200 mph = 0.26 mach
700 cfm = 233 mph = 0.30 mach
800 cfm = 266 mph = 0.34 mach
900 cfm = 300 mph = 0.39 mach
913 cfm max = 304 mph = 0.40 mach


2.75" piping
5.9365625 sq in = 2.96828125 x 2
300 cfm = 82 mph = 0.10 mach
400 cfm = 110 mph = 0.14 mach
500 cfm = 137 mph = 0.17 mach
600 cfm = 165 mph = 0.21 mach
700 cfm = 192 mph = 0.25 mach
800 cfm = 220 mph = 0.28 mach
900 cfm = 248 mph = 0.32 mach
1000 cfm = 275 mph = 0.36 mach
1100 cfm max = 303 mph = 0.40 mach


3.0" piping
7.065 sq in = 3.5325 x 2
300 cfm = 69 mph = 0.09 mach
400 cfm = 92 mph = 0.12 mach
500 cfm = 115 mph = 0.15 mach
600 cfm = 138 mph = 0.18 mach
700 cfm = 162 mph = 0.21 mach
800 cfm = 185 mph = 0.24 mach
900 cfm = 208 mph = 0.27 mach
1000 cfm = 231 mph = 0.30 mach
1100 cfm = 254 cfm = 0.33 mach
1200 cfm = 277 mph = 0.36 mach
1300 cfm max= 301 mph = 0.39 mach

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbozxi &raquo;</TD></TR><TR><TD CLASS="quote"> Of course it creates lag. 2inch will be fine I make 255whp on 2inch piping stock dseries.</TD></TR></TABLE>

I didn't say it didn't create lag. Ok, so maybe I did, but I meant not enough to worry about and I also mentioned that. I haven't been able to find the post here on HT that gave the added lag in seconds, but I did find this post that mentioned the difference between 2.5" and 3" piping being an additional 200-300rpm (barely noticable). If I remember right the time in seconds was like .25-.35 seconds difference. When you step up to a BIG turbo lag is measured in thousands of rpm. http://forums.evans-tuning.com...+pipe

 

if your turbo has a 2 inch outlet why would you go any larger. wouldnt that make no difference? or is it just the fact that its easier for air to flow through the larger piping?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by simike &raquo;</TD></TR><TR><TD CLASS="quote">

I didn't say it didn't create lag. Ok, so maybe I did, but I meant not enough to worry about and I also mentioned that. I haven't been able to find the post here on HT that gave the added lag in seconds, but I did find this post that mentioned the difference between 2.5" and 3" piping being an additional 200-300rpm (barely noticable). If I remember right the time in seconds was like .25-.35 seconds difference. When you step up to a BIG turbo lag is measured in thousands of rpm. http://forums.evans-tuning.com...+pipe </TD></TR></TABLE>
If the piping can flow enough air to meet your HP goal there will be no advantage to using larger piping just added lag. It depends on your HP goals. I'll take all the added response I can.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The Stance &raquo;</TD></TR><TR><TD CLASS="quote">nope no rods or pistons.......im actually going to try and make 300 whp on a stock internal d16a6....the only modification motor wise will be arp head studs......and a p30 i/m modified to fit the d16....</TD></TR></TABLE>
Goodluck hope its not your daily.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Drum and Bass Racing &raquo;</TD></TR><TR><TD CLASS="quote">if your turbo has a 2 inch outlet why would you go any larger. wouldnt that make no difference? or is it just the fact that its easier for air to flow through the larger piping?</TD></TR></TABLE> On the cold side of the intercooler it could be an advantage to use larger piping.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbozxi &raquo;</TD></TR><TR><TD CLASS="quote">If the piping can flow enough air to meet your HP goal there will be no advantage to using larger piping just added lag. It depends on your HP goals. I'll take all the added response I can.

Goodluck hope its not your daily.


On the cold side of the intercooler it could be an advantage to use larger piping.</TD></TR></TABLE>
i was going to buy a kit that was 2 inch to the intercooler from the turbo, and then 2.25 to the tb. im thinking this might be too small now?. i have a gt30r and its only going to be on a stock block for a few months then a built 1.8 is going in and i will probably double the boost. maybe i should get 2.5 all around? or 2.5 from turbo to ic and 3 to tb now so i dont have to step it up later?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Drum and Bass Racing &raquo;</TD></TR><TR><TD CLASS="quote">
i was going to buy a kit that was 2 inch to the intercooler from the turbo, and then 2.25 to the tb. im thinking this might be too small now?. i have a gt30r and its only going to be on a stock block for a few months then a built 1.8 is going in and i will probably double the boost. maybe i should get 2.5 all around? or 2.5 from turbo to ic and 3 to tb now so i dont have to step it up later?</TD></TR></TABLE>I would go with 3in to the T/B, and use what ever is closest to the turbo outlet size for the hot side most like 2.25in. You are talking about big HP there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbozxi &raquo;</TD></TR><TR><TD CLASS="quote">I would go with 3in to the T/B, and use what ever is closest to the turbo outlet size for the hot side most like 2.25in. You are talking about big HP there. </TD></TR></TABLE>
the more i look at 2 inch pipe its pretty damn small anyways , after my block is done i hope to max out this turbo

 

Fluid Mechanics! (does anyone know it and can help?)

 

To help discuss piping size dont just worry about the flow amount 2in, 2.5in, and 3in can handle. Worry about what pressure is needed in the pipe to carry the cfm to the engine. for the same cfm you need to push more pressure in the 2.5 than the 3. The lag is neglidable versus the two. When you want to be lower on your compressor map because of pressure drop in the piping, then step up to a larger diameter.