RxRolla

iTrader: (1)

Ok so I got an s4 T2 with a blown engine about a month ago. I had an engine in great condition laying around so I swapped it. I just wanted to get the car running and last night I did. Now reality kicked in when I started putting the exhaust together. It has stock DP (fat stock one) to 2.5" pipe to a high flow cat to a muffler to 3" pipe to Apexi n1 single.

Now my problem is that I dont have a stock exhaust to put on the car and the wastegate is not ported. I searched around here to see if anyone has had the same problem but only found people with straight pipes and 3" DP not with an actual free flow cat and muffler in between. I will get a Boost gauge today and see how things look.

Do you guys think this will really affect me in a negative way?

Thanks

RxRolla

iTrader: (1)

Drove car today with a boost gauge connected and it never went over 5psi.



Guess Im good

RxRolla

iTrader: (1)

But now thinking about it...



Is this normal???? Im only hitting about 5 psi at late rpm's (about 5k) on every gear but I do have an apexi 3" cat back and an HKS cone intake. I mean Im glad its staying low but it also feels too low.

Also at what pressure should I be really worried?

Maybe its the muffler in between.

Go48

iTrader: (7)

Could it be warmer ambient air temps providing lower boost? What was the air temp during your run? Five psi does seem a little low for a S4 with the freer exhaust and intake and the stock wastegate. Check all vacuum lines and connections, including the connection to your gauge. Try it again when cooler air temps come along to see if it jumps up.

My S5 with intake/exhaust setup similar to yours, but with the wastegate ported to about 35mm equivalent, is running about 8 psi in 60 degree air temps. Prior to that without the wastegate ported I was easily getting 12 psi. I understand that fuel cut occurs around 8.6 psi, so I would worry when boost approaches 10 psi or so. That's assuming you have a fuel cut controller/defencer installed on the car.

RxRolla

iTrader: (1)

I would say it was in the high 70's. It does seem weird. I guess I should try it at night since its pretty hot today too. The thing is that its hitting 5psi at about 5.5k. Im kind of glad its not spiking up but it also felt kind of low.

Could it be that the muffler and the high flow cat are holding it back like a stock one? Its got the stock DP-Highflow cat-muffler-apexi can