Exhaust options

[rhjames]

While everyone has their personal preference for exhaust set ups, I ran across a slightly different take on getting it done.

We purchased a set of Hooker Header sidepipes, trying duplicate the same idea that has been offered to Corvettes in Can-AM competition and other 70's and 80's road course competitions that Corvettes were running in.

Hooker does not offer header sidepipes for the 928, but does sell the "fake" ones----they have three of the four primary tubes blocked off, but are otherwise fully functional with 4 inch collector/sidepipes.

Our preliminary installation uses the stock manifolds and down pipes, but to tie into the header sidepipes it posed a challenge. The solution we came up with is this: cut the down pipes just before the front muffler, and then switch sides with them. Right to left, left to right. Remember, the down pipes turn inward, and we needed them to turn outwards. A short piece of flex pipe was then used to connect the down pipes to the header sidepipes. Flex pipe was used for two reasons: I didn't have a pipe bender available at the time, and the flex pipe allowed us to use clamps to hold the pipes, instead of welding the connections. This also allows for any engine vibration to not be transferred to the sidepipe mountings.

Our long term goal is to: install MSDS (or similar) headers, cut the header collector off leaving only the primaries, open the three blocked tubes on the Hooker units and connect the primaries to those tubes on the Hooker units.

There are good and bad with this installation.

First the good:

Weight reduction. The OEM front muff into (custom) twin 2.5 pipes to the rear set up that was previously on the car weighed 120+ lbs. The sidepipe setup "as is" weighed in at less than 50 lbs total. Over 70lbs weight reduction. I verified this with a set of scales weighing each piece of each exhaust system.

Reduced backpressure: (probably no backpressure at this point, as there are no mufflers in the 4 inch collectors---due to back order). With the slip in mufflers installed, Hooker claims more HP than just open headers---their claim, not mine.

Reduced under car heat: might make a difference in traffic with the A/C, but we believe getting the heat from under car is a good thing....

Looks: for those who like chrome, it's a good thing. Installation went well, but did have a few challenges. They are close to the body, tucked up nice and neat. Nothing protruding out past the outside edges of the tires/wheels.

Sound: for those who like it loud, it doesn't get much louder that this.....And with the cam lope of this Euro, it does sound like a super comp car with open headers.....teenage son loves it---go figure.

Better idle: very strange, and don't know why or really how to equivocate this happening. Previous start up idle was at near 2000 rpms, now it's at 1200 and settles down quickly. No other changes, car/weather/temperatures, during or after exhaust system swap. Idle is now smoother, and throttle acceleration is more crisp. I offer no explanation as to why.


Now the bad:

Looks: the purists will have a field day with this---I can hear it now--- "How could you even think of doing this to a Porsche, much less a 928?", they will ask......---or worse----Please be civil with your comments. (Then again, why would someone do this to a Corvette? I could ask.....They did it without regard for negative comments about what it looked like, as I recall, performance was the real issue). Sorry to offend those who can't believe this idea.....It will be OK.

HOT PIPES: Yep, girlfriend found out first time out, even after being warned that getting in and out would be dangerous to bare legs.....they will burn you.

Noise: these things are like riding in a drag car with open headers (at the moment) until the slip in mufflers are shipped from back order. If you want a quiet car, this is NOT for you. With mufflers in the tubes, it should be equal to an AC Cobra's noise level (I hope).

Clearance issues: could be a problem, but these hang no lower than anything in front of them (I.E. engine oil pan, alternator, A/C compressor, front spoiler, etc.). you will get into trouble trying to go over speed bumps and the like, but if you are careful (and you should be careful driving something that sits this low to the ground), you should have no trouble.

Jacking the car up: the front part of the primary tubes (4 of them) will block access to the factory front jacking point. There are solutions to this issue, but I won't get into that in this discussion.


Conclusion:

This is definitely not for everyone. It is an experiment for us, to say the least. We hope for better performance and judging by what others have advertised with header additions on their 928's, we anticipate good results by eliminating the under car systems that are currently in use by many of you these days.

With the addition of the Euro hybrid engine later this summer, it should be a fun combination to enjoy.





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[dsh]

I think it looks kinda cool... I'd like to know how much quieter it will be with the slip in mufflers, though.
what year is your euro?

[m21sniper]

Looks good, but this thread is useless without audio.

[Rixter]

this has been done by Wayne in NY, though not with the twisted look

[rhjames]

1980 Euro------

Slip in mufflers on back order---not sure when they will arrive.


Audio at present is the same as any Super Comp dragster or door car----open headers volume with the same amount of cam lope.