Any info on JBA's 2" Y-Pipe

cbrkris · #1 (**permalink**) 01-20-2005, 04:21 AM

I have just received my JBA headers and a Gibson Muffler (but have not installed them). I was looking at the y-pipe and noticed it looked very restricted. Has anyone had any experience changing the y-pipe out? Are there any dyno results on the Internet showing the gains (if any) with the change? I am looking for low-end torque for towing. Any information would help. Thanks!

Jack Burton · #2 (**permalink**) 01-20-2005, 07:23 AM

Quote:

Originally Posted by cbrkris

I have just received my JBA headers and a Gibson Muffler (but have not installed them). I was looking at the y-pipe and noticed it looked very restricted. Has anyone had any experience changing the y-pipe out? Are there any dyno results on the Internet showing the gains (if any) with the change? I am looking for low-end torque for towing. Any information would help. Thanks!

Hey Kris,

I've swapped out the y-pipe along w/the JBA headers. I had the y-pipe installed first and felt it gave better me a little better throttle response and smoothed out the shifts a bit. Some guys felt that it doesn't do anything.This is a mod that isn't dyno documented.

Take a look at these pics of the JBA & the stock y-pipes JB

http://www.tundrasolutions.com/photo...cat/500/page/1

http://www.tundrasolutions.com/photo...cat/500/page/1

RockyMtnRay · #3 (**permalink**) 01-20-2005, 07:49 AM

Don't be misled by what visually appears to be a restriction in the stock Y-Pipe. Since this is a junction that Toyota could have designed in a multitude of ways without much difference in difficulty/cost of manufacture or installation...and since Toyota's engineers have access to far, far superior gas flow modeling software and hardware (including super computers) than a very small company like JBA ever will...it would be exceedingly prudent to understand why Toyota designed it as they did before you go willy nilly replacing it. When it comes to assessing flow performance, visual observation and common intuition are often really poor ways of understanding sophisticated engineering solutions.

And having some understanding of fluid dynamics, I see the Toyota Y as having the characteristics of a laminar flow venturi design so the gasses coming down one branch of the Y actually cause an extraction suction for gasses on the other branch and cause the two gas streams to be smoothly melded with little power robbing turbulence. In my engineering mind, the Toyota Y is a superior design for flow when compared to the rough, very turbulence inducing collector design of the JBA Y pipe.

Furthermore, the Toyota pipe is stainless; the JBA pipe is aluminized steel. For those of us who have to deal with MagChloride coated winter roads, the JBA pipe is a sure ticket to rust-out.

My philosophy about modifications to this engine and its associated intake/exhaust systems is don't mess with the Toyota design unless you have a very deep understanding of fluid dynamics and thermodynamics or you have in your hands solid documentation (like Dyno results) that clearly show that Toyota, for understandable reasons such as manufacturing cost, chose a lower performing design. One of the very few cases where that's the case is the exhaust manifold...clearly headers work better but are far more expensive to manufacture and install than the stock manifold. Otherwise, Toyota's designs...done with world class engineering talent and world class engineering/performance modeling software/systems....are very, very likely to be superior to anything a small aftermarket company will come up with. Unlike GM/Ford/Chrysler, Toyota seldomly takes the cheapest route when it comes to component design and you're going to be very hard pressed to find an aftermarket design that's truly better. IOW, "mod-itis" may make you feel better but it's unlikely to actually improve your truck's actual performance.

Personally, I feel the stock Y pipe is better for both performance and durability reasons than the JBA pipe and my truck will keep its stock Y pipe.

Jack Burton · #4 (**permalink**) 01-20-2005, 07:55 AM

There it is in a nutshell..... Theory vs. actual real world "Butt-O-Meter".....

RockyMtnRay · #5 (**permalink**) 01-20-2005, 08:07 AM

Quote:

Originally Posted by Jack Burton

There it is in a nutshell..... Theory vs. actual real world "Butt-O-Meter".....

And the "Butt-O-Meter" is a notoriously inaccurate measurement tool. All it takes is a little more (or even different) sound and 99% of Butt-O-Meters will report "better" performance...even when the actual (dyno) performance is slightly reduced.

I'll take theory (and world class engineering)...over the "Butt-O-Meter" anyday.

Jack Burton · #6 (**permalink**) 01-20-2005, 08:15 AM

Quote:

Originally Posted by RockyMtnRay

And the "Butt-O-Meter" is a notoriously inaccurate measurement tool.

And speculation is any more accurate.....???

RockyMtnRay · #7 (**permalink**) 01-20-2005, 08:29 AM

Quote:

Originally Posted by Jack Burton

And speculation is any more accurate.....???

Sans hard (dyno) evidence and when it's based on sound engineering design, absolutely yes.

dezert_rida · #8 (**permalink**) 01-20-2005, 09:36 AM

The factory Y pipe is a joke. They shrunk the tubing down very small which is an obvious restriction of flow. Sometimes reality is right in front of your face.

Im more impressed with torque\HP that I can feel as I drive my truck rather than what a dyno says.

All car manufacturers mass produce things as cheap as they can to get vehicles sold. Performance is not the top priority. If they could make the system in alluminized and make it last, im sure they would use it instead of stainless too.

benjams123 · #9 (**permalink**) 01-21-2005, 12:00 AM

Talked to JBA today and the guy told me "some people" have experiecned a massive 2-3 Hp gain! Keep in mind that the Y pipe is not necessary with the JBA headers. They are a true bolt in design. So if you talk to anybody who tells you that you need the Y pipe they don't know what they are talkin bout (ORW). That's right some guy at ORW told me that I needed to buy the Y pipe and have it installed with the headers. So I called JBA and they said "Nope" don't need it. What a joke! Save your dough and put it towards something else. And, Oh did I forget to tell you...avoid ORW.

cbrkris · #10 (**permalink**) 01-22-2005, 03:15 AM

Thanks, It looks like I will be saving $250 and just installing my new ti- JBA headers and Gibson muffler.

Muleskinner · #11 (**permalink**) 01-23-2005, 01:41 PM

I built a custom Y pipe using a Flowmaster brand "two into one" Y merge pipe. The primary inlet tubes are 2" and the outlet collecter tube is 2 1/4". I used 304 stainless tubing forward of the Y pipe to replace the stock tubing.

Did the modification increase HP? Not sure. But I can tell you after cutting the stock Y pipe open, the stock two primary pipes entering the Y connection are smashed down (restricted) as they enter the outlet pipe on the stock Y pipe.

I would have to take an overall measurement of the smashed part of the primary inlet pipes and use math that "I don't understand" to ascertain if the crushed area of the pipes really restricted the flow.

For me, building a custom unit using stock diameter