kevino

I know the TID mod has been discussed to death, but I couldn't find a thread with this information. I was wondering, If I do the TID mod using a 3" ID vs. a 2.5 ID pipe, will I have more horse power? It seems to me that since the pipe has to eventually downsize to 2.5 to fit the turbo, then it wouldn't make a difference to use a 3" pipe. Any thoughts? THANKS

NZConvertible

A 3" pipe will cause less restriction than a 2.5" one, period. It doesn't matter that the turbo inlet is 2.5" (2-3/8" actually), the air still has to pass through the TID, and the faster it goes (less area = faster), the harder it is for the engine to suck it. Basic fluid dynamics.

How much difference it makes depends of all you other mods, it might be very little, but given the minimal extra cost of a 3" set-up, you might as will do what works best.

kevino

Well, I'm still not sure if it makes a difference or not. If you are considering fluid mechanics, then the turbo inlet does make a difference. Even if you aren't running any kind of air filter at all, the amount of air you are sucking in is still dependent upon the diameter of your turbo inlet. At some point in the piping, the diameter has to go from 3 to 2.5, so I just don't see it making a difference if that occurs right at the turbo or 10 inches away. Another reason I'm considering 2.5 piping is because I am still running the air pump, so 2.5 will give me more clearance.

kevino

Any other opinions?

usmcjsy

iTrader: (1)

2.5 should be fine. I am running 2.5 IC piping and I bought a 2.5 TB inlet duct off ebay and it seems fine. I have a 3" TID, so I am going from 3" down to 2.5". I have not had any problems and the car still seems to have sh*t load of power.

kevino

"sh*t load of power" --- nice.

NZConvertible

It makes a difference to overall airflow, but it makes no difference to the fact that it's harder to pull air through a 2.5" pipe than it is a 3" pipe. Restrictions in a system are cumulative; they all add up to the total flow restriction. Remove or reduce one of these restrictions, even if it's not the worst one in the system, and flow will increase.

RotaryBuddha

iTrader: (4)

are these any good for a replacement TID.

http://cgi.ebay.com/ebaymotors/ws/eB...category=38634


and why is it the the n/a one looks exactly the same

http://cgi.ebay.com/ebaymotors/ws/eB...category=38634


this is not a question about the filter i know the filters from ebay suck. blah blah blah. dont want a lecture on it.

NZConvertible

They seem to have conveniently forgotten about the AFM...

RotaryBuddha

iTrader: (4)

would i be able to hook the afm at the end of the pipe then the filter to the afm?

gerbraldy

as long as the pipe isn't too long to fit it in the engine bay with the afm+filter attached, I took a 3" intake I had off a neon from the shop and cut it up alittle and works perfect. Your not too far away from me, I live right down by Sarasota.

NZConvertible

The "kit" only has one coupler, but to connect the AFM you'll need two (plus clamps).

kevino

NZConvertible, I thank you for your responses, and judging from the number of posts you have and the incredible amount of times I've seen your name appear in question responses, you undoubtably know what you are talking about. However, considering the original question, I can't see 10 inches of 3" tubing making that much of a difference compared to 2.5 inch tubing (or slightly less anyway). I understand that the engine may have to work a slight amount harder to pull the air (kind of like drinking coffee through those tiny coffee mixing straws). But, considering that the majority of the tubing ( in an 88 TII in this case) is mostly around 2.5 diameter (IC and TB), then I can't see 2.5 intake tubing as being that restrictive. Even if the diameter is that much smaller, the volumetric and mass flow rates will still be consistant with the maximum flows capable of the IC and TB tubing. This is how I view the situation, if I am wrong in this then I am sorry to challenge you intellect. In any case, I thank you and all who have responded.

-kevino

NZConvertible

I'm not saying it'll make a huge difference (in fact I said "it might be very little" in my first post). I just figure if you're going to go to all the effort to do this, you might as well make the most of it. But if your air pump is going to make a 3" TID difficult then stick with 2.5". I'm sure you'll be happy with it, since it's still a big step up from the stock TID.

Just don't say it'll make no difference...