89 CSX-VNT 3" exhaust?????

[turbojerk]

I’m currently contemplating the idea of installing a full 3”Ø mandrel exhaust system on my 89 CSX, but I recently heard from a source that the VNT cars don’t respond well to ANY sort of an exhaust modification from stock.

Obviously I don’t want to spend the money on an exhaust system if it’s only going to cause problems and lack of performance…

Can anyone shed some light in the whole VNT with modified exhaust issue???

Thanks:thumb:
Troy

[Rebel Rob]

I have read that some where when doing research on Exhaust on this forum. I'll have to do some searching later and see if i can find it. Also talk to billy I think he might have looked all this stuff up. He is obsessed with making his CSX original but still have some extra performance

[dodgeshadowchik]

2.5" would be good. that's what i have on mine and it runs fine.

i have also read that the 3" will cause issues....

[turbojerk]

2.5" would be good. that's what i have on mine and it runs fine.

i have also read that the 3" will cause issues....

Well the reason that I wanted to go with 3” is because I have a brand new 3” downpipe collecting dust on a shelf at my shop.

[dodgeshadowchik]

ahhhhhhh, i see!

from what i read, the 3" is too freeflowing for it, so it causes overboost problems. however, if u used your 3" dp and downsized the rest of the system, you may be allright then. just a thought.

[thx138]

My experience. Removed the cat from a 90 vnt car. Not much change. Went to a Dynomax over-the-axle kit with a better flowing muffler (not a really free flowing unit) and I started to get boost spikes, but it would settle down (in warm weather). When the temperature started to drop the spikes would get bigger and stay long enouhg for OB to kick in. When the temp was below zero I had to add a reducer into the tailipipe to create a restriction just to keep the car driveable.

So, from my experience, your are wasting your time with anything much over an opened up stock system. A 3 inch system with a stock cal would be asking for driveability issues at alomost any temperature.

[JamesL]

My experience. Removed the cat from a 90 vnt car. Not much change. Went to a Dynomax over-the-axle kit with a better flowing muffler (not a really free flowing unit) and I started to get boost spikes, but it would settle down (in warm weather). When the temperature started to drop the spikes would get bigger and stay long enouhg for OB to kick in. When the temp was below zero I had to add a reducer into the tailipipe to create a restriction just to keep the car driveable.

So, from my experience, your are wasting your time with anything much over an opened up stock system. A 3 inch system with a stock cal would be asking for driveability issues at alomost any temperature.

+1. While there are cals available that would help, the VNT is a PITA to control properly. I run a 2.5 system no cat high flow muffler. My VNT has a 28 wheel though. I see boost spikes up to 22-25 psi. A little alcohol injection does wonders though.

[90Dodgevnt]

Don't do it.

Boost control with the VNT (I had a VNT25/VNT28/VNTS60) and it was pain to control. I saw spikes w/ the VNT28/VNTS60 upwards of 25+

Stick with a full 2.5 inch...


:thumb:

[turbojerk]

WOW!

How'd this get split into 2 posts??

[1966 dart wagon]

intresting, good to know :D also i had no idea of a vnts60

[BadAssPerformance]

WOW!

How'd this get split into 2 posts??

somehow it was a double poasted thread... all merged now :thumb:

[badandy]

Convert it over to a TII or S60 turbo and be done with the issues. Save the VNT for collectability if you so choose.

[turbojerk]

Convert it over to a TII or S60 turbo and be done with the issues. Save the VNT for collectability if you so choose.

Not an option!

The car only has 17,000 miles on it.

[glht_omni]

jamesL probably has the best out put setup for a vnt that you can build, some porting would go along ways but a full 2.5" mandrel bent high flow exhaust would be the most flow you would want with a either vnt25 or 28.

[badandy]

Not an option!

The car only has 17,000 miles on it.

Than leave it stock IMO and find something else to have fun with:thumb:

[BadAssPerformance]

+1 to leave it stock w/ only 17k miles.. dont you have a couple other cars to "F" with? ;)

[glht_omni]

17k.....dont even drive it, just stare at it lookin all pretty in the garage with a 1/8" of wax on it!
if your not happy with the omni anymore, i guess i would be nice enough to get it out of your hair, let me know when i can come take it off your hands, lol.

[dodgeshadowchik]

so you're the one who bought the nice low mileage car!!

AGREED. Keep it stock and just stare at it!!! there are plenty of other p-bodies out there in need of go-fast goodies!

[jl93sundance]

17k.....dont even drive it, just stare at it lookin all pretty in the garage with a 1/8" of wax on it!
if your not happy with the omni anymore, i guess i would be nice enough to get it out of your hair, let me know when i can come take it off your hands, lol.

Yeah but whats the fun of that, cars are meant to be driven:nod:

[turbojerk]

I agree with the "keep it stock" statement 100%, but some things can be swapped back to stock in a moments notice if need be. I would never discard the original stuff for any reason. I mean ya gotta have a little fun with'em right!?!?

I've already been told by others to remove the fiberides w/tires and store them off the car since they still have the factory rubber on them.....

http://farm4.static.flickr.com/3097/2817694006_2dfaf4d730_b.jpg

[glht_omni]

Yeah but whats the fun of that, cars are meant to be driven:nod:

yeah but at 20 years old with 17k mile, its not meant to be driven, its past that point, the 100k+ ones are the drivers, this is a show piece, garage queen.

that car is absolutely beautiful:nod:, just drive it to sdac only so you can snag 1st place in its class.
defintely store the wheels.
maybe just throw a 15psi fwdp cal on it and drive it on sundays.

[jl93sundance]

yeah but at 20 years old with 17k mile, its not meant to be driven, its past that point, the 100k+ ones are the drivers, this is a show piece, garage queen.

that car is absolutely beautiful:nod:, just drive it to sdac only so you can snag 1st place in its class.
defintely store the wheels.
maybe just throw a 15psi fwdp cal on it and drive it on sundays.

After I though about it, you're right it shouldn't be driven very often

[glht_omni]

my buddy had a 44k mile csx and it took him 4 years to put 2500 miles on it.
my 66' pontiac has 43k original and i have only put 400 miles on it in 1 1/2 years.

[gvare001]

You guys are right, don't drive the cars, store them and wax them as often as possible so that when you're old and senile your grandson Ferris Bueller shall enjoy them while taking as many as possible downtown rides.:partywoot:

[dodgeshadowchik]

Oh Gawd Thats Beautiful!!!!!
:love::love::love::love::love:

[Directconnection]

Mine had a 3" JRB system w/3" Ultraflow and no cat. It boosted rock solid at 15psi with the custom 15psi cal, buit in 4th gear under load at wot it would pull about 17psi.

Read 5digits MOB article on how to control overboost on the vnt...

[turbojerk]

Oh Gawd Thats Beautiful!!!!!
:love::love::love::love::love:

Maybe I could get so lucky as JT and get a photo opp with you and the car.;)

[turbojerk]

Mine had a 3" JRB system w/3" Ultraflow and no cat. It boosted rock solid at 15psi with the custom 15psi cal, buit in 4th gear under load at wot it would pull about 17psi.

Read 5digits MOB article on how to control overboost on the vnt...

I will have a look for sure. I still haven't abandoned the idea yet....

[dodgeshadowchik]

Maybe I could get so lucky as JT and get a photo opp with you and the car.;)


lol! bring it on by!! :)

[glhs875]

Mine had a 3" JRB system w/3" Ultraflow and no cat. It boosted rock solid at 15psi with the custom 15psi cal, buit in 4th gear under load at wot it would pull about 17psi.

Read 5digits MOB article on how to control overboost on the vnt...


Where is this article located?

[Directconnection]

SDML of about 8 years ago.


Might be on www.thedodgegarag.com too