SV6 - Reducing exhaust vibrations

[CHDSV6]

I've been reading through some old threads about exhaust changes to the VZ's, but I'm still wondering what the best fix for my problem is. I have a 2 1/2" twin system with hi-flo cats and pacemaker headers on a VZ SV6. The system gives a nice note and a bit more poke on the throttle, but sometimes there's a low-frequency hum at certain rev ranges (4th @ 1500 rpm is common) that shakes the cabin badly. It's like the same vibration you would expect from a set of subs kicking but more constant. It's difficult to see in the mirrors when this happens as they vibrate so much.

Anyways, I really wanted to know if doing something like changing the rubber retainers to tighter/looser softer/harder may remedy the problem as most of the vibration seems to transfer to the body through these?

[impulsesv6]

could try changing the rubbers, also do you have a flexjoint in the rear section, like standard has.

when i had my exhaust first done, i told them to leave it in, then i had the rear section done again and told them to leave it off, and i do notice alot more vibration in the rear tips, but my car doesnt shake.

when was your car last serviced - the engine could be running rough

[Not_An_Abba_Fan]

The best way to fix the vibration is to fit stainless flexible bellows to the pipes just in front of the cats. This isolates engine movement from the exhaust and will stop the exhaust moving around because of engine movement.

[CHDSV6]

I'm not sure if there's a flex joint back there - I haven't had a look under the car since it came back last time, and didn't tell them if I wanted them in or out. Most of the vibration is occuring up near the cats, so I it sounds like Not_An_Abba_Fan may be on the money with it being engine movement transferring down the system. Might get the local fitter to have another stab.

Also, for anyone considering 2 1/2" in the future, I had some dramas with my factory cats when the system was installed. The cats were the only thing not changed out originally, and with the Pacemaker headers, the cats sit VERY low to the ground with the 2 1/2" pipework. I ended up dragging the cat over a speedbump at about 1km/h and cracked the wafer inside. I had to change it anyway due to the wafer rattling inside after this, so it is worth the extra bit to get them done straight up if your considering headers.

[impulsesv6]

yep,the triangular original cats are no good for ground clearance, thats why i had hiflow cats fitted when i had my exhaust fitted

[CHDSV6]

impulsesv6, the note on your signature; "236.3RWHP 14.9@94.8mph" is that the performance of your SV6 or some other car? If it is, would you mind telling me a bit about your setup as I want to make somewhere between 200-300 horses at the wheels also. (I know I'm going off topic!) I've been looking into a Vortech V2 non-intercooled supercharger system with an FMU, injectors, etc. and obviously the exhaust thats already on. One of our local performance shops has advised me against a piggy back ECU, and has told me I'm better off getting him to dyno tune the factory ECU instead. Ill probably look at getting a CAI plumbed to the supercharger too to reduce intake temp.

Any thoughts would be really appreaciated!

[impulsesv6]

yep mine. the info is in the my ride section, everything else is secret lol, and yes do go full computer remap, not piggyback.

check out raptor supercharges, thats the way i'll be going...

that drag time was also a very poor effort - a .989 reaction,lol- but it was my first time out

[CHDSV6]

Had a look at yours over at MyRide, very nice machine you have there! I can understand you don't want to give all your secrets away! Ill probably get a strut brace too after seeing how cheap they are in your thread... I hadn't really looked into them but I figured they would be up around the $200 mark or something. I was going to buy the Impulse Blue SV6 but I ended up with the black as the bank manager who was setting up the loan had one for sale coincidently.

I was looking at the CAPA supercharger .Our local Dyno man is a CAPA agent so I think that will be the easiest. I'll post up some details when it's all done (when I convince the same bank manager to give me the coin!)

[kiwi nz]

Hi
I was wondering how much you paid for your pacemaker headers in Australia. Also I got told that they would bolt on straight to the cats and if that's the case why are people saying they hang too low to the ground?
I'm looking at buying some in New Zealand for $645.00+gst.
Thanks

[impulsesv6]

577 inc gst,
and they dont bolt straight up, the piping is totally different.
but a cat-back system will bolt up to the rest of the system

[Not_An_Abba_Fan]

The extractors will not bolt up to the cats because the cats are up so close to the manifolds. I can do Pacemakers for the VZ for $490 inc gst.

[CHDSV6]

I'm not really en expert on mechanical stuff such as exhausts, but I was told by the exhaust installer that it also has to do with the pipes changing to a larger diameter, therefore they are slightly lower to the ground and this makes the cats sit a bit lower also. It's unfortunate that the cats are in the perfectly wrong spot for going over speed bumps - just as your wheels roll off the front of the bump the cats get dropped down from above onto the speed bump I found.

I suppose the pacemaker headers might also have a sligtly longer vertical leg as they come down from the engine than the factory pipes, this could make the cats a bit lower too - correct me someone if I'm wrong. I'm not sure the per-part price I paid either - the whole system cost me $1300 inc gst and fitting time.

[sv6emss]

I have recently put a 2 x 2.25in to 2.5in single exhaust on my car. It sounds great, but it vibrates a lot. Sitting at lights it feels like the car is missing, if you pop the bonnet the engine is silky smooth but then the cats and 2.25 inch pipes are vibrating badly. Also im getting that annoying heat shield rattle.

Anyone else had this problem? If so how did they fix it? Any help appreciated.