gopede

Hi!

I´m thinking about buying a Lindsey 4´exhaust for my 944 Turbo S. Does anybody know how loud they are? In sweden we have 95db on most tracks so I can´t be louder then that. (I have already talked to Lindsey and they have not measured it)

Thanks!

Peter

odurandina

with a Turbo, big pipes are favorable over smaller ones. but, 3 inch pipe is already huge and will make tons of power. 4 inch pipe is dire.... and should be considered woefully unnecessary for anything but a high budget racing program, and probably offer only moderate gains. you might consider 3 1/2 inch pipe into a 14 inch round magnaflow resonator (part #14161) with a 3 1/2 inch core located near the front.... continue the 3 1/2 inch, then transition to 3" pipe at the S-bend (mandrel bend pipe). all straight pipe from there will allow very near maximum power, as flow will be determined by the 3 1/2 inch pipe, the shock wave will terminate at the resonator and the short 3 inch bottleneck will simply increase the exhaust velocity, thus allowing the remainder of the system to mimick a 3 1/2 inch exhaust. (and still not be horribly loud). but, you can also add something like a 14X5X8 inch magnaflow at the back.

this is the resonator i'll be running for my v8 exhaust. would work really well for a turbo.


.

Paulyy

just to compare..

My turbo back true 3" exhaust has 2 blow through "turbo mufflers" one in the middle and one at the end and it is 102 db at 4600 rpm.

It all too depends on how you measure the noise.

For Australia, Melbourne. On the streets it's measured at about 2m away at a 15° angle from the tips at a specific RPM. (changers per car)

JustinL

I have the lindsey 4" exhaust. I don't find it that loud, but don't have any measurements. I never get hassled by the police here and it's not the loudest car on the race track either. The problem with the 4" is the lack of clearance to just about everything from the axles to the ground.

HoBoJoe

Stick with 3" unless you're shooting for over 500hp. You can add extra mufflers/resonators to quiet it down for your tracks.

s14kev

"Shock wave"? "3 inch bottleneck will simply increase the exhaust velocity"?

This description sounds like someone who is not an engineer trying to pretend to be an engineer with no knowledge about fluid dynamics.

On a side note, the Lindsey 4" is very liveable when configured with the recommended cat converter and muffler. I removed the cat and muffler and substitued them for straight pipe. Configured in this way, it is obnoxiously loud (can't start it up without waking neighbors just at idle loud). The standard lindsey 4" starts as smaller pipe and progressively increases in size up to 4".

Exhausts should focus on maintaining high exhaust gas velocity which is best achieved by maintaining high exhaust temperature (avoid rapid cooling of exhaust gas flow), reducing turbulence (avoid unnecessary bends) and reducing rapid gas expansion (avoid sudden increases in pipe size which introduce turbulence). Odouradina's suggestion on 3.5" pipe necking down to 3" makes no sense at all from a flow perspective.

odurandina

the one thing you got right....

for a non-turbo engine.

the front of my exhaust offers minimum resistance.

the rear of the exhaust i suggested allows practicality to be maintained w/ desired levels of noise reduction vs performance.

Reimu

If you're under 30 years old get a 4" exhaust

If you're over 30 get a 3"

If you're 50 or over remain stock

XrussianX

^^^^^^^
Best answer lol

JustinL

HAHAH So true! I bought my 4" when I was under 30, then started pricing out 3" exhausts the last couple years to replace it.