thanks Apat, I am trying to go fully catless, but am trying to track down OEM dp’s first, to have on reserve for when I have to get my emissions done. Right now I just have pre-cats gutted to pass emissions.
Where are you located, a lot of us get away with fully catless even though we have emissions, a strict visual is really the only way you get caught (or a tail pipe sniffer test).
[quote=“Maddog,post:22,topic:3030”]
yep, had 0 problems passing without cats in washington.
91gl - AR is the right place for this sort of thread, to which I have nothing to contribute except thanks for going the extra mile in the name of making our cars even more awesome. If I didn’t already have an exhaust, I’d buy yours. 91 is a solid guy to buy stuff from so someone snap up his 2.5". /end free plug.
Just saw this. Awesome stuff! There seem to be a lot of factors involved in exhausts that most people overlook. That hooker muffler seems pretty awesome, I like the idea of something quiet while cruising and ballsy when you step on it.
91, thanks for doing this!! It will be really informative. I was thinking of going with the JHM RS4 2.75 for mine, but I will wait for your results before doing anything.
Great thread, will be very helpful for when I put together my exhaust.
It is amazing how much the Hooker mufflers flow in comparison to stock. 91 do you know how much the FI mufflers flow
Looks like some of us will have 2 hookers in the back of our cars soon.
http://www.holley.com/data/types/pictures/Maximum%20flow%20graphic.jpg
Here’s hoping to an Aussie dealer, if not someone who can ship them
But for $72 can’t go wrong
another thing for everyone to consider based on the measurements presented is what they actually mean
15" WC means 15 inches of water column, or 0.54 psi assuming the water is 4*C
the straight pipe I’m gonna assume is per foot
the flow is the measure of how much flow will go through the pipe or muffler given a dP of .54 psi, or with a loss of .54psi of exhaust pressure
more flow can be achieved but it will require more dP, or more pressure loss
pressure loss slows the gases and limits scavenging
Mufflers, x-pipe and piping came in yesterday. Will update soon.
Also will be picking up a welder in order to tack it together so I can then take it to my fab guy and have him tig weld the whole system together. But I will be trying to learn as well for future projects.
Very excited to see this develop. Pics!!
nice, you got 220V in the shop?
I’m gonna grab this once I recover from buying a new car:
http://www.amazon.com/Hobart-500500-Handler-115-Volt-Single-Phase/dp/B0002PS7SA/ref=pd_cp_hi_2
http://ecx.images-amazon.com/images/I/41BeJhjpnoL.SL500_AA300.jpg
Yup, gonna get a cheap one to fuck around with until I get better than buy a nice one
update?
bumping again, it’s been almost a week?
might sound dumb but if i for say were to make or buy a 2.75 catback wouldnt that help the car breath beter since all my bolt on’s gets me rather close to the stock power level of an rs4? which with jhm’s rs4 is running 2.75?
the rs4 does well with the 2.75" due to the revs, you should be fine with a 2.5" for any stock motor S4 … 91 is looking bigger due to the built motor, and the potentialy ~800bhp the car could be making
justincredible’s tests showed that the catback is a bit of a restriction on his nitrous car but I can’t remember if there was a big difference when he ran all motor/no catback vs. his nicely designed 2.5
yeah good point, I forgot about spray. the nitrous cars should have a higher exhuats volume:intake volume ratio since the liquid N2O is going to expand and decompose in the cylinder…
basically more power=more exhaust=more backpressure… with a blower you have the increased intake charge pressure to force it out, but with nitrous you don’t and a restriction will become evident