Here goes:



The pipe that was measured before is the prototype version. This one here is the production version.

 

Does anyone actually make one that has a 2 1/2" ID? Or do they have to be custom made?

Miguel

 

the kakimoto R is like a 2.6x ID with a 2.5 ID Flange i believe

ask Mafay2

here:

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My systems are 2-1/2" OD but I use a larger ID 3 bolt flange and flare the start of the B pipe to be 2-1/2" - 2-9/16" ID per the picture below. This way there is no mismatch with the 2-1/2" ID outlet cat.

 

The Type One b-pipe diameter is quite ideal for stock and modified motors. A 2.5" or greater ID is really more beneficial on a highly modified motor, I think.

But anyways, Type One, great value for the money!

 

I agree, don't know why everyone is so uptight about loss of a few mm or so in the b-pipe when you probably have better internal work to worry about. Like Spikey said, unless you have a highly modified motor, then you should worry about the size of the b-pipe.


[Modified by N1-R, 8:01 AM 3/21/2002]

 

I have heard enough that a 2.5" ID exhaust that ppl are losing low-midrange response out of the 1.8L B18C engine. IMO, even with BIG cams the bigger exhaust doesn't benefit much.

 

i think that 2.5" ID is way too big for a NA motor with light to med mods. i spoke to someone at Thermal and they said that a 2.5" ID exhasut is way too big for a NA motor.

 

This is the reason why I feel it is important to have the IDs match up at a given joint. The flange on the right is the Tanabe RM as received and run on the car with a 2-1/2" cat for about 2 weeks. The picture on the left is with the flange cut off and a 2-1/2" ID adapter welded in place. This simple mod netted 4whp in the VTEC range on an ITR with a AEM CAI, Toda header and 94006 Car Sound Cat. That mild steel adapter cost $40 plus the labor to install. That IMO is a pretty good bang for the buck. The customer also stated that the car was more responsive in the low range.

Notice the exhaust ring on the Tanabe flange, this will create turbulence.


When the 2-1/2" OD exhaust was fitted to a stock ITR in the header test, it lost 1/2 to 1 lb-ft from 3000-3400 and was virtually identical to stock up to 5200, after 5200 is where the gains were. None of my customers have told me that they lost low to mid range power with the exhaust, some have said they've notice gains down there.

SMSP - Who is pro any 2-1/2" exhaust, just make sure the B pipe flange is correct

 

SMSP and others, couple of Q's:

1. Are the 60mm systems from Japan 60mm OD or ID?

2. Most ppl always recommends mandrel-bent, but some have said it doesn't matter (ala Jeff from IB), even on highly modified motors. Is there a real difference in power (there definitely is a diff in flow, but that diff may not necessarily translate to a large diff in power) between a mandrel-bent cat-back and crush-bent cat-back? Anyone have dynos that show the diff (equal comparisons only, like 2.25" crush vs. mandrel or 2.5" crush vs. mandrel, not a 2.25" crush vs. 2.5" mandrel)? Thanks.

 

Damn, in some car with only I/H, I don't even see a 4whps increase by bolting on a 60mm aftermarket catback. I guess it really show how important to have matched cat and b-pipe flange. And if someone butt can feel the 1/2-1 lb-ft lost of torque, your butt should worth as much as a dyno.

I think all the exhaust system are listed in their OD.
So is all JDM headers have a 2.5" ID collector too? I know JDM 4-1 don't, but how about Spoon, Mugen, Toda, JUN, SMSP, Hytech and others?


[Modified by EGtoR, 8:23 PM 3/21/2002]

 

OD. Quoted diameters are for OD of piping.

 

I've gone into this before, but to be technical about it there is no piping in your exhaust system. It is tubing and tubing is always spec'd per the OD and wall thickness. Wall thickness is the gage of the tubing, i.e. 16g=.065" and 18g=.049". Systems from Japan are spec in mm as is the thickness, i.e. 1mm or 1.5mm.

Header collectors are also spec'd by their OD. JDM headers are 65mm (2-9/16"), my B18VTEC headers are 2-1/2" OD as are the HyTech headers also I believe, but don't quote me on that.

 

SMSP: can you go over my second question above...mandrel vs. crush bent? Is there really a noticable difference in power? Is the difference only noticable on highly modified motors? Thanks.

 

I have not done a back to back test like you've asked. For the hell of it I got a piece of 2-1/2" tubing bent on a 90 at a muffler shop and its OD lost about .300" at the worst point. Common sense will tell you that mandrel bends have to be better. Before you could say one was better than the other you would have to test but with the same resonator and muffler and the locations of each. I frankly don't want to spend the $ or time testing a crush bent system since my gutt gives me an answer. But since I haven't tested 2 identical systems back to back, one mandrel and one crushbent, I guess I really can't recommend either.

SMSP - Who will still be building his cat back systems from mandrel bent tubing.

 

Does anyone know if the Type On B-pipe will work with a stock OE ITR muffler?

 

Survey says...Yes!

 

Thanks SMSP! Yeah, reasoning would tell you that the reduction in diameter would impede flow a bit. I just wanted to see if you, or anyone else, had done any tests to show that this impedance in flow actually translated to a significant power reduction. Thanks.