LP928

I have a 1979 928 Euro manual and like to downshift some into turns or when coming to a stop. It has a rear muffler bypass and makes "popping" noises when I downshift. I believe that that is gas igniting in the exhaust, but was wondering - is it bad for the engine or exhaust? Any damage that could be done? Would I have to replace the exhaust eventually? I know its not a full fledge race car but it is fun.

Thanks for any info

Kyle

123quattro

It's normal.

belgiumbarry

my Roe blown SRT10 is one popping orchestra... and i like it

WallyP

The popping often indicates that air is being introduced to the exhaust somewhere close to the engine.

jpitman2

Mine did similar when it was lean...
jp 83 Euro S AT 52k

LP928

So I take it is not a problem

thanks

123quattro

That noise is always there. You can just hear it now that you have a more open exhaust. All my cars have open exhausts, and they all make those noises.

LP928

Hey, also wondering how much these stock manual transmissions can take - are they tough? Can they take downshifting regularly? not severe like 5th to 2nd but just one gear or two at a time to slow down to a stop.

Jadz928

I would not suggest heavy-duty engine braking. Brakes are far cheaper than the other bits experiencing the forces. OTOH, the tranny can take downshifting all day long, and it's best to match revs, though no need for double-clutching (box is syncromesh).

Tampa 928s

I heard that there is no syncromesh in first on a 78, also its prone to second gear grinding due to bad syncros.

LP928

I believe you're right about the syncromesh in first I have a 79 and even if your rolling 3 mph with clutch in to a stop sign and you put it in first it grinds, I have to stop or come to an almost complete stop to put in first.

WallyP

All Forward Gears are synchronized on the early cars, All Forward Gears and Reverse are synchronized on the later cars.

SharkSkin

Agreed, mine (rebuilt) has a synchro on 1st... and it actually works!

LP928

Okay, I probably need a new syncro for first then.

FlyingDog

Mine did it more when it was lean, but it has always done it. High flow unbaffled exhausts will increase occurrence and volume.