Installing exhaust on 996TT, what to upgrade while it's out
Discussion
speedbird1000 said:
Grind out the inlets of the headers (left picture after; right pic before), I could not believe how much of a restriction there was from the welds - the grinding (difficult as the metal is very hard) made a much bigger and smoother flow area and had no problems since.
That bit of "restriction" doesn't amount to a hill of beans and remember too the engine is turbo-charged (so in this case man helps God fill the chamber...) and some back pressure is desirable to keep from blowing too much air through the engine while the intake and exhausts valves are open at the same time.
The OP can grind out the header inlets if he wants to but while it might make him feel better it won't make a difference.
Be sure *all* the grit is out of the exhaust system so there's no grit to possibly foul the turbos or the sensors or even the converters.
Sincerely,
Rockster.
Actually this is the header's outlet depicted. So the substantial weld restriction that was removed is right in front of the turbo's turbine blades, and it is much better to have smooth exhaust flow into the turbine blades, which is the case now. This will just mean the turbo is driven better by the exhaust flow, which is exactly what you want. Also, too much back pressure means you risk too much heat at the cylinder's outlet which you don't want.
Rockster said:
There is a saying in engine building/tuning business that God fills the chamber while man empties it.
That bit of "restriction" doesn't amount to a hill of beans and remember too the engine is turbo-charged (so in this case man helps God fill the chamber...) and some back pressure is desirable to keep from blowing too much air through the engine while the intake and exhausts valves are open at the same time.
The OP can grind out the header inlets if he wants to but while it might make him feel better it won't make a difference.
Be sure *all* the grit is out of the exhaust system so there's no grit to possibly foul the turbos or the sensors or even the converters.
Sincerely,
Rockster.
Having worked on a lot of turbocharged cars, grinding out the headers where they meet the exhaust ports can make a significant different. Headers and their size (and wrapping or ceramic coating) can have a significant impact on the behaviour of the turbo, power and torque curves. And this is not subjective, there is plenty of rolling road data to back it up.That bit of "restriction" doesn't amount to a hill of beans and remember too the engine is turbo-charged (so in this case man helps God fill the chamber...) and some back pressure is desirable to keep from blowing too much air through the engine while the intake and exhausts valves are open at the same time.
The OP can grind out the header inlets if he wants to but while it might make him feel better it won't make a difference.
Be sure *all* the grit is out of the exhaust system so there's no grit to possibly foul the turbos or the sensors or even the converters.
Sincerely,
Rockster.
kazino said:
I am having a Carnewal exhaust fitted and am wondering if there would be any work worth doing while the exhaust is out?
The car is 10 years old now and has done about 40k miles
You could get the headers wrapped (cheap) or ceramic coated (expensive but lovely) which really helps with heat management and gas speed. Both of which will help on a turbo.The car is 10 years old now and has done about 40k miles
Old Trout said:
You could get the headers wrapped (cheap) or ceramic coated (expensive but lovely) which really helps with heat management and gas speed. Both of which will help on a turbo.
absolutely. you don't want to loose heat between inlet of header and turbo, because the gas volume then contracts as per the first law of thermodynamics, so you in turn loose gas speed and hence force driving the turbine. The 996 turbo standard header is quite stocky already, but I am sure it can be improved by wrapping etc. Old Trout said:
Unless your dump valve is leaking the only reason to get a replacement is for show.
Also, this is a relatively straightforward DIY and no need to be anywhere near exhaust. Time would be better spent checking for corroded/loose turbo and exhaust heatshields and the condition and operation of turbo wastegates/actuators while you're underneath.Thanks EvoSlayer will make sure they are looked into. Anything else that should be checked for a car around this age or any other preventative work one should be looking at?
EvoSlayer said:
Also, this is a relatively straightforward DIY and no need to be anywhere near exhaust. Time would be better spent checking for corroded/loose turbo and exhaust heatshields and the condition and operation of turbo wastegates/actuators while you're underneath.
Old Trout said:
Having worked on a lot of turbocharged cars, grinding out the headers where they meet the exhaust ports can make a significant different. Headers and their size (and wrapping or ceramic coating) can have a significant impact on the behaviour of the turbo, power and torque curves. And this is not subjective, there is plenty of rolling road data to back it up.
Well, in this case I suspect the 996 Turbo owner made one of the most expensive mods to gain single digit hp ever.And for likely hp gains that falls inside the window variability of the rolling road used to measure this gain.
I looked at a pic of my Turbo's exhaust headers and they are not welded on the outside so grinding the weld bead away takes away a substantial amount of the metal holding the exhaust pipe to the header flange.
This is an exhaust crack waiting to happen.
Wrapping the exhaust might have some benefit but I'd be leery of raising the operating temp of the turbos above their design limits.
Sincerely,
Rockster.
EvoSlayer said:
Old Trout said:
Unless your dump valve is leaking the only reason to get a replacement is for show.
Also, this is a relatively straightforward DIY and no need to be anywhere near exhaust. Time would be better spent checking for corroded/loose turbo and exhaust heatshields and the condition and operation of turbo wastegates/actuators while you're underneath.
Just had my heat shields, all bolting and turbos replaced.
If your Turbos do come off, have a serious look at your oil pipe work and the NRVs (Non Return Valves). This would be a great time to replace as much of that as possible.
EvoSlayer said:
With something bigger I hope?....It's the law 
Ok, AET Turbos may have sent some lightly modified ones. They said something about didn't have standard ones in stock, I forget the details 
;)Redline also mentioned something about having to install a remap as well, again, I forget the details
;)Homer J said:
EvoSlayer said:
With something bigger I hope?....It's the law
Ok, AET Turbos may have sent some lightly modified ones. They said something about didn't have standard ones in stock, I forget the details ;)Redline also mentioned something about having to install a remap as well, again, I forget the details
;)EvoSlayer said:
Nice work, Good lads at AET across in Normanton, they built my turbos up around 4 years ago and they're still pushing strong. If you need to borrow a vbox to play around with when your done give me a shout.
Cheers fella. I'm trying to persuade Leigh from York that upgrading is the only way forward.........He ain't biting though 
Back to the Op though, have a shop around for Turbos too. As Ken mentions all the time, often when working on The exhaust if the turbos need removing, this can lead to problems if there heavily corroded. Get them off and at least have an inspection / overhaul
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