I/C piping bigger than throttle body?

[98spydert]

Doesn't make much since to me to have intercooler piping larger than the ID of your throttle body because it would just be a fat bottle neck. Am I right in thinking a 60mm throttle body doesn't need larger than 60mm piping or are there any sort of gains to be found with larger pipes?

 

[sweet97]

Most IC piping is 2.5" or around 63mm, about the size of a stock TB. Guys?

 

[AWDspoOLiN]

I'm in the process of getting parts together to do a major upgrade on my basically stock performance and I've been thinking about the same thing. I think that having a consistent diameter throughout the system would be more efficient. I've read that having too large a diameter hurts boost response. At the same time, my logic tells me that the system is pressurized so it shouldn't matter too much. I've decided that I'm going with a consistent pipe diameter for my own peace of mind. I figure that cylinder heads are ported, ideally, to match the intake and exhaust runners so why not do the same for the turbo>intercooler>throttle body pipes.

 

[98spyderboost]

Well the reason you see differences in spool times due to different pipe diameters is because the larger diameter pipe simply creates more airspace for the turbo to have to occupy before it hits is limit(spool). I would just plan with standard 2.5" tubing and route as straight and short as possible. I'm about to start bending the tubing for my own FMIC. I will be using 2.5" and a 1g throttle body w/ 3" intake from ram air box to intake port on turbo.

 

[sweet97]

I'm usig2.5" also. I go lucky and found a 3" HONDA intake, polishd aluminum that with a few inches cut from one end placed my filter outside the engine bay where the stock IC once was so the turbo will have much cooler air to begin with to compress! mark

 

[98spyderboost]

I'm usig2.5" also. I go lucky and found a 3" HONDA intake, polishd aluminum that with a few inches cut from one end placed my filter outside the engine bay where the stock IC once was so the turbo will have much cooler air to begin with to compress! mark

Agreed, this is a detail many people overlook. Whats the point of trying to cool the air with a FMIC if your pulling hot air from the engine bay? Personally I like to see the filter mounted outside the bay. Shows attention to detail.

 

[b17tuner]

Hmm... The turbo is going to make the cold air hot anyway...

 

[anconover]

Yes but would you rather bring in hot air, to a HOT turbo, or cool air to a hot turbo? Even if it only makes the slightest of difference. But honestly, i dont see the need of a 'cai'.

 

[b17tuner]

Yeah, Doesnt matter. Shortest root. Turbo wants to most air, Not the coldest/densest like na. Atleast thats my take on it.

 

[98spydert]

Air isn't heated by passing through a hot turbo (maybe slightly), it's heated as a result of being compressed. If you've got air compressed to 20psi inside those pipes it's going to be HOT! The CAI would make a difference in off boost performance like cruising around town, it MIGHT feel a little peppier.

 

[98spydert]

Back to the pipe diameter... So a large pipe with smaller t body would only create longer spool times and probably produce the same over all flow, if not worse from the bottle neck. Huge power set ups could benifit from 3" pipes but not with out a larger tbody and even manifold. Anyone think differently?

 

[sweet97]

The IC pipe size is almost notam issue as 2.5" is standard. How many IC's do you see coming with 3" inlet/outlets?
As far as turbo's and cool air goes or even NA motors they like cool air. Like the way they run on a cool night. I figure if my turbo is taking in 75* air or 125* air to compress the 75* air should put out cooler air to the IC helping that do it's job more efficiently. I have a 3" pipe runnig from the original IC position to the turbo. It will get plenty of air, cool air. I have a pic if anyone sends their email addt iI will send the pics. Mark

 

[gixrman]

Doesn't make much since to me to have intercooler piping larger than the ID of your throttle body because it would just be a fat bottle neck. Am I right in thinking a 60mm throttle body doesn't need larger than 60mm piping or are there any sort of gains to be found with larger pipes?

Here is a example of throttle plate size to HP reqiurement for turbo cars I found in a book by G. Bell on forced induction.

Throttle plate (mm) Maximum HP

50 250
56 310
62 390
70 500
75 600
85 750
90 830
100 1000

Now thats just at the TB. Larger pipes will cause lag and a loss of volceity.

When air is heated o2 is displaced, the cooler the air is going into the turbo the cooler it will be coming out. The turbos job is to compress air, if its already cool and dense the better the o2. you make your own judgement.

 

[98spydert]

That chart doesn't compare to dsmers. TONS of people make way more power than 390 on a 60mm tb (not even 62) and the big 700hp+ guys are usin 75mm acufabs.