Recently I put a badmab header and zzp 3" catted downpipe on. Before this all I had was a muffler and was hitting 17psi on my 2.8. Now after full exhaust I'm still hitting 17psi. Shouldn't I be seeing less boost now that I did full exhaust?

 

Technically yes. Less restriction should mean less boost. Wierd

 

same thing with my car but im more like 18 19 psi

 

Idk with the superchargers doesn't the pully dictate how much boost is made regardless of the exhaust?

 

no because if your moving the same air through less restriction it will create a lower psi reading but same amount of air is still their

 

I have an exhaust and DP, and still the same boost, i was assuming it was just the header still keeping the psi high

 

i got a LT Header + Catted DP(blown out cat though ), 3" Res, and 3" piping to the stock axle back and my boost dropped...only about 10.25-10.5 psi @ 7K RPM(stock pulley)

 

Do you think maybe the highflow cat could be clogged? Is there a way to tell?

 

yup take it off and use a longer resonator. I run a full vibrant setup on a 2.7 and only hit 16.6 at 7k, after I removed my vibrant high flow cat.

 

i dont have a cat and still my boost didnt drop

 

arnt you consider a higher elevation?

 

its like 1200 ft so i wouldnt consider that high

 

Here is something that I don't get... everyone on here says that exhaust effects max boost.. I don't see it mechanically.

Boost is the measure of intake pressure. period.

If you had head work and opened up the valves more, I could remotely see having a very minimal drop in psi because of a better flowing head.

 

if boost cant get in and out it will stack, clogged cat on a 2.9 will make 20lbs. everything is in line thus affecting all. your thinking way to much into it.

 

so explain why my boost is the same

 

3in to a 2.5 in catback the transition is your restriction with a full 3in exh you would see less

 

what size is your header? still 2.5"? your exhaust is only as big as your smallest point. So if you have a 2.5" outlet for your header and a 3" dp that could be the explanation.

 

It's 1.75" primarys and 3" collector.

 

boost is a measure of restriction...whether it is in the intake mani, the head, or the exhaust

 

mine went up but i also dropped from a 2.9 to a 2.6 but went with a lth and full 3" catback...im making 16-17 at 4400 ft elevation

 

From Wikipedia, the free encyclopedia


A boost gauge is a pressure gauge that indicates manifold air pressure or turbocharger or supercharger boost pressure in an internal combustion engine....

A boost gauge is used to ensure excessive pressure is not being generated when boost pressure is being modified to levels higher than OEM standard on a production turbocharged car. Simple methods can be employed to increase factory boost levels, such as bleeding air off the wastegate diaphragm to 'fool' it into staying closed longer, or installing a boost controller. To prevent the Air-fuel ratio from going lean (caused by increasing the boost beyond the fuel systems capacity) care must be taken to monitor boost pressure levels, along with oxygen levels in the exhaust gas, using an air-fuel ratio meter that monitors the oxygen sensor.

A boost gauge will measure pressure in either psi or bar; many also measure manifold vacuum pressure in inches of mercury (in. Hg) or mm of mercury (mm Hg).

 

I was about 17.5 to 18 before the badmab and went to a solid 17 once it was added.

 

Congratulations, you copy and pasted a Wikipedia article that told you where boost reading is drawn for a gauge. Which has nothing to do with what is being discussed here. Open the exhaust up, boost will drop, port the head, boost will drop. It's not that hard of a concept...

 

^^^this most people that have a familiar set up to me except port and polished head and full exhaust push 20lbs and i only push 16-17

 

Flow > Boost