Hahn stage 2 kit...

04 eco cavy

2" borla exhaust way too restrictive I know...

I decide to put on a QTP electric cutout...

Normally boost around 6-7 PSI.

Welded in the cutout and took it for a spin...

When the tires broke loose in 3rd gear I thought holy hell this isn't right, look at boost gauge and its at 14PSI...

What the hell???

Somone please explain...


A buddy of mine thinks perhaps the exhaust was restricting the turbo boost so the previous owner might have played with the wastegate rod just to get 6-7 PSI
He thinks with the cutout open it is now breathing so much better that I am getting boost spikes...

What the hell happened?

close the cutout 6-7 PSI
partially open 10 PSI

wide open 14+ PSI..
Not cool on stcok motor.

scary @!#$ man

Does it just spike up to 14 then settle back to 6 or 7, or does it stay at 14+? Not too familiar with the Hahn setup, but is it internal or externally gated? I don't believe the size of the exhaust would limit your boost on a turbocharger, supercharger possibly, but not turbo.

Sounds like something is funky with your wastegate really, perhaps too weak of a spring(if externally gated) or a bad wastegate actuator on an internal wastegate. Interested to hear back on this.

Yeah, you're right. Turbos work based off of pressure differential to get the turbine to spin. If you have a large amount of backpressure due to a restricted exhaust then you will only get minimal boost pressure. Lower the tension on the wastegate to give you your target boost while the cut out is open. This will greatly reduce the boost pressure while the cut out is closed, but it will make your setup much safer.


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91 Cav "GT"<-- R.I.P.
91 Cavalier Wagonstein - Turbocharged wagon goodness
You can take my rifle when you pry it from my cold dead hands.

or check and make sure your gauge calibrated. for my car there have been times where i have started the car and saw 18psi. but then when i let off i go down to like 4 vacuum. which i should be at like 15-20 vac cruising. so i turn the key off turn it on, let it reset and then start the car then its right

Vincent Morris wrote:or check and make sure your gauge calibrated. for my car there have been times where i have started the car and saw 18psi. but then when i let off i go down to like 4 vacuum. which i should be at like 15-20 vac cruising. so i turn the key off turn it on, let it reset and then start the car then its right

A. That only works on boost gauges that are electric. Although it was not mentioned as to what kind of boost gauge is being used.

B. Seeing how suddenly there was a lose of traction in 3rd gear, this leads me to believe that the boost gauge was correct.


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91 Cav "GT"<-- R.I.P.
91 Cavalier Wagonstein - Turbocharged wagon goodness
You can take my rifle when you pry it from my cold dead hands.

a friend of mine with a turbo'ed honda civic has the same issues when he upgrade his exhaust system to 3 inch instead of 2inch,try to ajust your wastegate, double check if you wastegate vaccum line is correct plug in and witout any damage to the line!, also verify if the wastegate rod has been shorten, if it's the case, readjust it




http://cavalierdomination.monchar.com

your computer has to learn the new set up so it is going to act a little funny, but that doesnt really explain why you had so much boost.

and did you even let the turbo break in at all?


Veritas Aequitas

peteyparker311 wrote:
and did you even let the turbo break in at all?

I've never heard of anyone ever asking that!!


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91 Cav "GT"<-- R.I.P.
91 Cavalier Wagonstein - Turbocharged wagon goodness
You can take my rifle when you pry it from my cold dead hands.

You can NEVER have too much boost. Look at it this way if you blow the bitch sky high you get to rebuild it and make it stronger lol.



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4 Cams...32 Valves...5 Liters...This Could Get Fun!

Skunk wrote:You can NEVER have too much boost. Look at it this way if you blow the bitch sky high you get to rebuild it and make it stronger lol.

If you build it right the first time then it won't ever blow sky high.


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91 Cav "GT"<-- R.I.P.
91 Cavalier Wagonstein - Turbocharged wagon goodness
You can take my rifle when you pry it from my cold dead hands.

^^^ you can have the strongest parts in the world but if your tune isnt right it will blow.

z yaaaa wrote:^^^ you can have the strongest parts in the world but if your tune isnt right it will blow.

You are 100% right. Sorry, I didn't elaborate. To me the tune is a major part of the overall build.


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91 Cav "GT"<-- R.I.P.
91 Cavalier Wagonstein - Turbocharged wagon goodness
You can take my rifle when you pry it from my cold dead hands.

I have hahn stage 2. The spring should have been a 6-8 psi spring. They could have maybe sent 8-10 psi spring. I have both. I would not run 14 psi on your car man. Your goona love the hell out of it but mine lasted 3 months with that fmu!!! only on like 12 psi!! It blew so hard i had parts of my motor a mile back!!! And it almost started my car on fire. You should make sure you have that 8 psi spring in it. Even if you turn that rod it hardley makes a difference. I have expermented way 2 many times with each spring. Take that actuator put correct spring in it unless you want to end up in the same boat as me and spend 3500 to get motor built!!!! But if you got the money do it.

Well Here's what I figured out...

You guys were right...

I think the borla exhaust was so restrictive that "the previous owner" must have cranked the wastegate rod all the way in just to get the 6-7PSI I was seeing...

Of cousre as soon as the restriction was gone the rod is still screwed all the way in and wammy I have 14+ PSI!!!

So my fix is to back the rod out a bunch I only have like 3 PSI of boost with the cutout closed and 7-8 PSI open...

Greddy profec b spec 2 will be here tomorrow and I will readjust with that...

Thanks for your help...

are you sure its a borla exhaust? isnt stock 2" why would borla make stock sized piping?

peteyparker311 wrote:your computer has to learn the new set up so it is going to act a little funny, but that doesnt really explain why you had so much boost.

and did you even let the turbo break in at all?

You really have no idea what your talking about do you?

You don't break turbos in. Hell the "break in" on mine when I put the HRC kit on was to go out front and lay a massive patch of rubber down thanks to the massive torque I suddenly had and then proceed to rip down the block a few times. Breaking in a turbo...HAHA funny.

Computer...learn new setup...WOW...enough said.



I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26

z yaaaa wrote:are you sure its a borla exhaust? isnt stock 2" why would borla make stock sized piping?

Stock is 1.75"

Are you using a boost controller?

I have a 8 psi spring in my w/g and i run 9, which is what my boost controller is set to.

with the exhaust closed I run about 6-7 PSI

with it open I can hit 14+

I got the boost controller installed and it seems to be fine now...

Hahn says I may need to port the wastegate???