Duckstu

I hate to say it,.. but I was a bit disappointed when I bought my 07 Turbo with the width of the power-band.

The turbos come on at 3,500,.. and redline is a measly 6,500.

I finally found a spec on the redline,.. and Porsche claims it is actually 6,750 (perhaps the tach needle is just tardy?).

My car came to me with cat-less Tubi exhaust,which should help the spool threshold a bit

The Cobb Accesport flash I have on it now raises the redline to what seems like to 6,900,.. but that still makes for a fairly narrow power-band. Having come from Subarus where the turbo is in by 3,00 or so,.. and the redline is 7,200 - 7,500,.... I find that it's some concentrated effort on my part to keep this car on the boil. And getting it out of the hole without smoking the clutch is a real trick.

THEN I read a Car & Driver review from back in 2006 or 2007 where they talk about no turbo lag from about 2,000 rpm and up. WHAAAA??? Is something wrong with my car?

Any of you have boost by 2,000 rpm?

I have a set of Do88 turbo inlet tubes in a box that I could try.

So where does everyone's turbos come on? And what do you see for redline?

aa909

My 07 TT was 100% stock when I bought it and I was disappointed with how sluggish the car felt at low rpms. Turbos wouldn't spool until I got it over 3K and the power band was as you describe (3500-6500).

Shortly afterwards I bought a europipe exhaust and immediately noticed the turbos would spoil earlier (below 3K RPM). I then installed a softronic tune and I can honestly say that the combination of the two has completely changed the low end responsiveness and power band. The turbos will easily spool in the 2000-2500 range now and pull hard to 7K. Very noticeable difference in low end power and responsivenes which was grossly missing with the stock set up IMO.

I hope this helps
Art

RugRunner

Art--which Europipe exhaust? Also, have you had it dyno'd since the mods?

aa909

I have the EP1. And no I haven't had it dynoed. But you don't need a formal dyno to confirm the turbos spool earlier and continue to pull to redline:

1) The digital read out on the dash clearly tells you that the turbos are producing boost at lower rpms vs stock. I've seen an obvious difference as described in my first post.

2) You can also hear the turbos whistle, especially with the Europipe, and again this is audible at lower rpms vs stock.

3) The tune holds full boost (17+ psi) through to the new redline vs stock (which only allows 14.7psi after ~5.5K RPM).

I actually think the stock car has plenty of power, it's the delivery of the power that I found to be unsatisfactory, especially at the lower end of the rpm range. If I did dyno the car I would expect that the area under the curve below 3500 rpm would be greatly improved based on the quantifiable metrics I described above. And obviously the top end power should be higher as well since full boost is available all the way to redline vs stock.

Art

Team Plutonium

I have to pay attention next time I drive when the turbos actually kick in, but I'm mostly very busy ****ting my pants when I hit the gas hard.

Duckstu

Thanks for all of the above Art.

I agree totally on the power being fine,.. but the power-band being rather narrow. With all the years of turbo'ing experience, more displacement and VTG turbos,.. I was expecting a wider power-band than the Japanese competition,.. not less.

As I said,. my came with the Tubi catless exhaust,.. and it looks to be an efficient enough design (and I like that it all connects together with V-Band clamps,..).

It looks like this.



The pipes coming off the turbos are a nice, smooth reduction from the 3+" turbo exit down to the 2.5" or so entrance to the muffler. It should be spool friendly.

Yet with that catless setup and stock tune, the turbos didn't come up until 3,500,.. and although I haven't yet data-logged it,.. it doesn't seem to spool much sooner now. Perhaps 3,350 or 3,400.

Could I have a stuck VTG rod? The car is from Miami,.. and has 19,000 miles on it. Everything underneath looked spic & span.

aa909

are you getting on the pedal enough? the turbos won't really spool down low if you are feathering the gas. For example, at low speed in 2nd gear you really need to be at 3/4 on the pedal to get the turbos to really spool at 2000-2500 rpm. And at higher rpms you need to floor the pedal to get full over boost (17+ psi) through red line.

Boeing 717

LOL I know man, I was thinking "how on earth could someone find this car sluggish??" The last time I stepped on it, it felt like a massive explosion was happening behind me that propelled me into the next dimension.

RugRunner

Good to know

roncooper

What other cars have you driven. A stock 997 turbo isn't all that exciting as it pertains to acceleration.

RugRunner

Art--I wasn't questioning you, just was curious if you'd quantified anything using a dyno. Great to know that you definitely saw a big (and positive) result!

Boeing 717

This is the fastest car I have ever drivin in my life. But its not stock, I really cant comment on what stock is like. However I only have a tune and exhaust I cant imagine its so dramatically different than stock.

dpert1

Agreed, I'm stock (for now) and it's the fastest car I've ever driven.

TB993tt

How are you doing your spool test ?

It should be done in 6th gear, start at about 1600rpm give it 100% throttle and let the revs build up to 3000rpm.

To monitor your spool you should either set the gauge in your rev counter to boost, duck tape your phone to the steering wheel and video what the boost is doing as the revs rise. One I did below, these are big VTGs so slightly slower on the boost spool.


Alternatively and more accurately data log using durametric logging rpm throttle % and boost (again do it in 6th)

Porsche's diagrams showing boost at 2000rpm on from loaded engine dyno tests and 6th gear should replicate this pretty well.

Duckstu

So that's how they're getting such unrealistic results.

The higher a gear you choose,.. the more it loads the engine,.. and the earlier the spool threshold will be. Also,.. the engine takes so long to wind up in 6th gear,.. that the shift-recovery portion of the spool is eliminated,.. and you get a spool threshold that is not representative of what you actually experience on the street.

That's pretty shady of them to do their tests in 6th to skew the results.

WHAT"S IMPORTANT is when you mat the throttle in 2nd - 4th,... when ddo you get boost? If the turbo's don;t come on until 3,500 rpm in those gears,.. then that's your effective power-band.

I can't say I've EVER gotten into positive boost in 6th. That gear is for quiet highway cruising only (or making 190 mph runs at an airstrip)

The industry standard is usually 4th gear on a 6-speed. Probably has to do with dyno tuning. You would never do a full dyno pull in 6th. Not only would you be in an over-driver gear,.. but the roller speed would be too high on most any dyno. Shops don't let you make 200 mph passes on their dyno.