pantera928

I recently bought an X pipe for my 1988 from Roger at 928srus. It looks like while the original exhaust/cats slips into the pipes going to the rear, the X pipe is larger in diameter and goes over the outside of the pipes going to the rear. Is this correct?
The pipes going to the rear are slotted to compress over the pipe from the cats. If the X pipe goes over the outside of these, how do you stop it from leaking? Even with those clamps that were included, it seems counter intuitive to me. Seems like a like a leak is destined to happen.
Am I thinking about the wrong?
Is this how it is supposed to go?
Been looking for pictures on the Rennlist but haven't seen any that show this connection clamp.
Thanks

ROG100

Yes that is correct. The original cat back pipes will be inside the larger diameter X pipes and once the joggled clamp is tightened around the joint it should be leak free. Remember to really tighten those clamps like we talked about. They will form the exact shape of the joint.
Remember the small seal for the clamp join.

pantera928

Okay thanks Roger
I will do more tightening.
Am thinking to reinstall the rear muffler. With the RMB and the X pipe, it sounds like an American hot rod.
Any ideas how I can make it sound more like a fine tuned European machine than a Vintage vette?
I like the sound of a Ferrari 360 Modena over the sound of my Pantera or Mach 1 for this car.
All are V8s so it must be possible. Yes?

Kevin in Atlanta

I have an X pipe, high flow cats, GT mufflers and GT rear muffler. The RMB was too raspy.

pantera928

Is this Kevin Berez? Got any audio of the set up?
GT mufflers much different from the S4 mufflers? Better sound and/or better flow?

Kevin in Atlanta

Sorry, no audio. They are different as are the GTS rear muffers And yes I'm that Kevin.

pantera928

Should I make those changes before I do the sharktuning or will it make much difference?
THanks
Greg

Kevin in Atlanta

Make the changes that you will keep. Then we can shark-tune that setup.

pantera928

Guess I need to listen to what yours sounds like before I make those changes.

Bulvot

It's very subjective, but I really like how mine sounded with the x-pipe, S4 resonators and RMB. It sounded exotic to my ears.

Also, getting a perfect seal was practically impossible. I have some wider wrap that worked better than what came with it. You may want to consider it if you have trouble with the seal.

pantera928

As you said, very subjective. Not a bad sound but just not the "euro" sound I want from the 928.
My 69 Mach 1, yes.

hacker-pschorr

Firing order and engine design have a lot to do with how an engine sounds. All Ferrari V8's are a Flatplane crank design where as most other V8's are Crossplane (including the 928). One modern exception is the Ford Mustang GT350 "Voodoo" engine and rumors say the new ZO6 or ZR1 engine will be Flatplane. That's why those two cars sound more like a Ferrari.

Another factor that figures into engine sound is firing order. The 928 shares the same firing order as other popular V8's like the Ford small-block. This is why 16V 928's with a single open exhaust sounds like a vintage Mustang. Other factors like engine angle (60 degree, 90 degree etc..) and valve configuration also affect the sound. The 5-valve design of the Ferrari 355 has a unique sound. Or if you put the exact same exhaust on a 16V 928 vs a 32V they sound a bit different.

Also maximum RPM's. Your typical Ferrari V8 revs to 8,000rpm or higher while our 928's are 6,500 or less.

There is one "trick" you can do to have a similar "Ferrari" sound with a Crossplane engine, but that involves making custom headers combining the primaries in a similar way a Flatplane crank would come together. One person did this about 20+ years ago, and here is a thread discussing the idea:
https://rennlist.com/forums/928-foru...ternative.html


Here is a good video on the differences between the two V8 engine designs:



As for the "Mustang" sound, at track events the sound of my 79 with open headers & a single 3" exhaust is often compared to the Mustang in Bullitt:

SwayBar

A 16v 928 Euro can sound like an exotic too with headers, y-pipe, and a single muffler.

The following is Road America, coming out of Turn 14 onto the front straight. The in-car video was captured by another participant.


That 928 is one of the best-sounding cars ever at RA, which includes all the ALMS/IMSA racers.

pantera928

Well, I tightened the clamps all the way down from the X pipe to the rear pipes and guess what? It still leaks at the joint! Not very audible but if you put your hand there, you can feel the hot air coming out!
Need a plan "B". Ideas anyone?


Also, reinstalled the rear muffler and like the sound a lot better.
Foe those who don'r remember, it is heavy as hell and hurts when you slip and drop it on your face!

hacker-pschorr

That's a good example. 10.4:1 compression ratio and aggressive (for a 928) camshafts also add to the sound of this engine.
At least I think it's 10.4, it's 10 something....memory fuzzy.

There's a good chance it will seal up once fully warmed up. Not the best plan but something to ponder.

I've never cared much for those clamps, but they are the only option for such a product to bolt onto the existing exhaust. I'm having V-Band Clamps welded onto my x-pipe for a better connection.

I'm glad I'm not the only one.