I will be getting a Protune in about 3 weeks. Question I have is whether I should get the turbo inlet installed before the installation or it is just a minor mod that it shouldn't really affect the tune. I am getting a custom tune for VF34 turbo.

Please advise...

turbo inlet tubes are usually bigger in diameter than the stock piece. thus allowing more/better flowing air to the turbo. in theory it would be better to install it before the tune. you want to get the most out of your professional tune. you are spending good hard earned money for it. ;)

i installed a perrin inlet pipe. let me tell you... it was an absolute whore to do. much harder than the turbo and injectors IMO. so good luck doing it. some advise, use some kind of lube to get it to fit over the turbo. and i had to use a pry bar inside and work around it. that was the only way i got it to work.

Do you think stock inlet hose could bottleneck VF34 turbo on a rather conservative tune around 270whp?

no you should be fine. i dont think a aftermarket inlet tube will net you that much more in power.

Here's a comparison of two TopSpeed-tuned STi's on the dyno (same day, within an hour of each other).

"avatarr" has: catless APS turboback (full 3"), APS header, colder plugs, walbro pump, APS CAI
"nhluhr" has: catless APS turboback (3"/2.5"), APS header, colder plugs, walbro pump, Typhoon intake, APS Inlet Pipe

http://wrx.dicknogs.net/tuning/topspeed_3-25-06/avatarr_vs_nhluhr.gif

Wow... is that the intake creating that much of power or it's turbo inlet?

install the inlet before the tune.

Here's a comparison of two TopSpeed-tuned STi's on the dyno (same day, within an hour of each other).

"avatarr" has: catless APS turboback (full 3"), APS header, colder plugs, walbro pump, APS CAI
"nhluhr" has: catless APS turboback (3"/2.5"), APS header, colder plugs, walbro pump, Typhoon intake, APS Inlet Pipe

http://wrx.dicknogs.net/tuning/topspeed_3-25-06/avatarr_vs_nhluhr.gif

Not a very good example. It's not the same car (motors may output differently based on their health) and the cars have different size exhausts and intakes. If the tests were of the same car with the only thing changing was the inlet hose then it would have been a better example. You have too many variables here to get a good idea of what the inlet hose (alone) will net you.

You really need to install it before the tune!

My speculation is the TIH maintains slightly less vacuum right at the turbo compressor inlet, meaning the actual pressure ratio of the compressor is lower. It's probably slight, but should help move air.

I'd be interested in seeing vacuum numbers measure right at the turbo compressor inlet between a stock and aftermarket piece. That would tell you want you really want to know.

I'd be interested in seeing vacuum numbers measure right at the turbo compressor inlet between a stock and aftermarket piece. That would tell you want you really want to know.
I think a lot of us would like to see these measurements. Not to mention with certain intakes other versus the stock one.

offset

the measurements of pre comp pressure are difficult to do properly due to the velocity of the airflow in that region. bernoulli is a pita sometimes, even if he gives us curveballs and airplanes. :lol:

the measurements of pre comp pressure are difficult to do properly due to the velocity of the airflow in that region. bernoulli is a pita sometimes, even if he gives us curveballs and airplanes. :lol:

...and refueling at sea.

Duncan

Not a very good example. It's not the same car (motors may output differently based on their health) and the cars have different size exhausts and intakes. If the tests were of the same car with the only thing changing was the inlet hose then it would have been a better example. You have too many variables here to get a good idea of what the inlet hose (alone) will net you.If anything, my tapering exhaust would HURT top end power, yet mine is well above his. So, there's that.

If anything, my tapering exhaust would HURT top end power, yet mine is well above his. So, there's that.

Not nessacerely. Everyone thinks that with turbo cars you need the biggest exhaust possible to make power. The bigger the better... that's not always true. Also, could be that your 06 motor is just stronger then his. To be honest with you... and no offense, but I haven't ever seen matching results from any 2 cars comming out of TopSpeed, even when the mods are exactly the same.

gopsu, i had to reduce advance in the spoolup region after installing a samco inlet tube last year. nothing else was changed but the inlet tube.

gopsu, i had to reduce advance in the spoolup region after installing a samco inlet tube last year. nothing else was changed but the inlet tube.

good info, ken. i'm thinking about picking up one of those fancy APS inlets. it's either that or a coolingmist setup :)