Offroad-Express

I went to a performance shop this afternoon to get a quote on an exhaust on my 80 series.

The guy told me that he suggested a 2.5" downpipe for about 800mm with a flexi then to a 3" straight through to the back.

I've read a lot on 80 series 3" exhaust systems which go from the turbo back and I thought this was the norm but from what this guy was telling me you want to allow a bit of back pressure.

Now people have almost died as a result of arguing about exhaust back pressure so I'm not interested in discussing it indepth but I would have thought the turbo provides it's own backpressure?

Mates of mine have put 3" from the turbo on their Safaris with good results and I agree with at least putting a muffler in there to apply backpressure but I'm not sold on the whole 2.5 to 3" deal.

Ideas?

backpressure after a turbo is a old wives tail
3" all the way

What was the quote worth? - if you don't mind me asking. I'm looking at going down the 3" route as well.

vvega wrote:backpressure after a turbo is a old wives tail
3" all the way

Agreed.

The only valid reasons to use smaller pipe on a turbo engine are to a) save money and b) change the exhaust note.

It was around $1000 which is about right.

Rage Exhausts make a complete 3" bolt in system

http://www.autobend.co.nz/rage/New%20Si ... oyota.html

When they last had a listing on Trademe I asked and it was about $1100 including freight.

Is he suggesting 2.5" downpipe because it's easier to fit?

That's what I plan to do, not because I think 2.5" is better, just because it's tight between my AC pump and my engine mount.

Back pressure on a turbo slows down the spool and can be used as a way of controlling boost. Basically you don't want it, unless you have an undersized wastegate.

4.2 turbo diesel equals 3" exhuast.

They ship those Rage exhausts to Aussie and sell them at half the cost here on Ebay. Go have a search. I emailed them about it and all I got back was a quote something like $1040

Yip just checked item number 120391244356

$449.00aus!

I was running a 3inch all the way on my old 12 valve cruiser. It was the rage one bolted up perfectly we fitted it in 4 hours.

Made absolutely no difference in the time to 100km/h. Did make it sound a lot better.

I then tweaked the boost compensator on the fuel pump and this made a big difference in my times to 100km/h knocked about 4 seconds off it.

I now have a 24 valve manual cruiser and in stock std form blows away my old modified to the max 12 valve. I am not putting a big exhaust on it as I got sick of the racket.

Maybe a LS1 would be the way to go????

80series wrote:Yip just checked item number 120391244356

$449.00aus!

Converted to NZD + shipping and any customs you might have to pay and it'll be up around $700 but it doesnt include a dumppipe. They claim they factory downpipe is 3" anyway so they don't include one but the factory one is paper thin and isn't the smoothest angle off the back of the turbo...

Yeah, I just sucks that a product from New Zealand can be bought for less in Australia than NZ!

Rocktruck wrote:I was running a 3inch all the way on my old 12 valve cruiser. It was the rage one bolted up perfectly we fitted it in 4 hours.

Made absolutely no difference in the time to 100km/h. Did make it sound a lot better.

I then tweaked the boost compensator on the fuel pump and this made a big difference in my times to 100km/h knocked about 4 seconds off it.

I now have a 24 valve manual cruiser and in stock std form blows away my old modified to the max 12 valve. I am not putting a big exhaust on it as I got sick of the racket.

Maybe a LS1 would be the way to go????

Cheers for your input, did you have any problems with WOFs and Police attention?

I'm just wondering if I should wait until I get my next wof before doing an exhaust.

i slapped a 3inch on my 4.2 safari, its turboed and has a coby muffler which doesnt make it any quieter really. its not that loud and its never been a problem with police or a warrent. sounds like a logging truck, even get a bit of turbo whistle comming through.