Bobby@Momentum

At Momentum, we design our parts with as much consumer input as possible. When we come up with options, questions and potential problems, we look to the consumer for help shaping the parts to what their needs are.

I am looking for some feedback on one of the pipes we use for our 350Z/ G35 turbo kits. The crossover exhaust pipe that connects to the header and the “y” up-pipe (the pipe joining both banks going to the turbo exhaust inlet) needs to have some form of flex joint in it to permit proper flange alignment on different vehicles. On all of our prototype pipes on multiple test vehicles, we have used interlocking stainless braided flex couplers or bellows. They are welded inline with the pipe and provide good flex for alignment and a nice visual appearance. For a daily driver, these are one of the best options. They are completely sealed, provide ample flex and can help with vibration. We have had them on multiple daily driver test vehicles for six months with no issues. On our track cars, a problem that we have found is that in high heat, high stress situations, like summer temps at the road course, they begin to crack and leak.

For those wanting to use our kits in constant extreme situations, the proper fix for this is to use a double slip joint with beehive springs holding it together. These are used on a lot of “race designed” parts and provide an answer in extreme situations where the stainless bellows would fail. There down side in a daily driver application is that they will build up some carbon on the pipe were they leak slightly. This is the way they are designed for expansion, and the slight leak is negligible to performance.

My question to you all, the end user, is would you rather see the double slip joint as an option for those that want to really push their cars, or not an option and used on every kit? The real question is how many people would be upset that their crossover pipe had a little carbon on it?

Below are a couple pictures with the bellow and the slip joint. Either would work for a daily driver, while the slip joint only works for extreme track abuse.

rcdash

iTrader: (18)

Can you use v-band clamps and allow either option? I personally wouldn't want a leak but wouldn't care if I had to replace a small exhaust part once/year, if it was easy and inexpensive (few hundred $$).

rrmedicx

iTrader: (54)

Slip joint and call it a day. Although it is overkill in terms of "is it really necessary??" for daily drivers??? At least you won't have to worry about people complaining of it breaking. I doubt once installed people will ever need to even look at it, so complaints of carbon stains are absolutely nothing to worry about.

SLIP JOINT. =)

ADMAN

iTrader: (9)

Being one that has had to replace MANY leaking flex joints living here in HELL, I pick double slip as well.




Wait, I mean DS FTW!!!

frankie945

iTrader: (35)

The only thing I do not like about slip joints. Over time heat will weaken the springs and then you most likely have a exhaust leak. I have owned many dirt bikes and some sport bikes with slip joints and ran into problems with springs getting worn out over time. Then again if it's a real snug fit it should hold up well. But it will be black after a few thousand miles. As for a Daily Driver I would say V bands, but that's just my opinion.

Edit: If installed right flex pipes will not break.

frankie945

iTrader: (35)

I have had two different Single Turbo kits and never a problem with any flex joints. It the quality is good and install is right there should be no problems with flex joints.

Shertown Turbo

iTrader: (2)

I have had to replace two flex joints on my car and it was not the most fun thing in the world. Especially since I did it in a garage with jack stands and not a lift. I vote double slip

str8dum1

iTrader: (11)

i say focus on fitting a 80+mm turbo in there and use flex joints.

All my race exhausts for my scooter use slip joints. Its a huge PITA when the springs come off and trying to stretch a new one often requires an injecton of nadrolone!

ToastZ

iTrader: (2)

Let the customer decide when the kit is ordered.

Support both options.

GT-ER

iTrader: (4)

How about having a V-band where the flex is along with the V-band currently welded ( in other words, having two V-bands ). V-bands allow some slack in alignment before tightening and they allow for some thermal expansion. I used to have V-band clamps on the exhaust piping in my Pontiac Grand Prix and they offered zero leaks and much flexibility in installation and removal. They also offered crack free daily driving.

psychoballistic

iTrader: (8)

If it were me I would be down for the flex joints also. Never had a problem with them, and with a lift they are imo pretty easy to fix, then again, with a lift what is more dificult?

MEI

I would go for the double slip as a relible choice, but what is the rating of the springs?

ADMAN

iTrader: (9)

Ben, unfortuanely, most people out there will probably like the flex joint because of the way it looks - not the way it performs. Again, they don't last long out here.

BoostedProbe

iTrader: (9)

When I did my kit, a flex pipe did the job just fine. Flex pipe and V-band = Win. The key is good quality stainless flex pipe.

ADMAN

iTrader: (9)

^^^ Very nice!!!

BoostedProbe

iTrader: (9)

If you are refering to my pictures, the turbo is located right behind the trasmision.

So far, most of the guys running hard core track events here are TT. I guess it all depends on who your are targeting. Personaly, I would try to build a kit that will work for 98% of my customers that do not go and track the car every weekend for 5 hours.


I can't really comment on the slip coupler because I have no experience with them. That is why I didn't vote, it wouldn't be fair. It does sound like the springs are a problem though... I guss if you have the experience, and it sounds like you do, the decesion is easy, isn't it?

frankie945

iTrader: (35)

I do like the idea of slip joints for use on a track or drag car.

ADMAN

iTrader: (9)

No question here. Try tracking a car in Vegas during the summer. The EGT are A LOT more than that. That's why I agree with the slip design.

terps

iTrader: (2)

i vote for double slip since it will make repair easier. i just found my crossover pipe cracked(next to flex section, but flex piece was fine?).

350Z400rwhp

iTrader: (4)

There will be no way to please everyone and I agree that 98% of people on here will never track their cars to the extent you are talking about. From what it sounds like, you are building a reputation for a kit that is track worthy and if there is not difference or leaks with a slip joint then I would go for that. Now if the slip joint causes noise under the car because of less flexing or something for the street drivers well then you should consider pleasing the 98% or just offer two options.