Too bad my car's out of commission at the moment. But it'll be very interesting to see what times does Mike get out of his PSI 550 car, if he still has it....

 

I'll tyr to get it done this weekend.

 

Chad,
Can you please explain a few things?

In order to obtain somewhat meaningful results, I would assume each of the parties that collects this data for you needs an exact procedure.

What is that procedure? Example.....lug along at 2,000rpm in 5th gear and then mash the throttle while timing the interval between "mash" and 0.1 bar on the Porsche boost gage?

Can you please explicitly outline the procedure you want followed?

 

I checked my stock K16 turbo on the way to work. It gets boost at 2600 in about 1 second, starts making boost at 1200 - 1400 RPM.
The way I did it was to get in third or fourth gear on level ground at 2600 and set the cruise control, wait a few seconds then floor it.

At 2000 RPM I get boost in 1.5 - 2 sec.
At 1500 RPM I get boost in 2.5 - 3 sec.

 

Chad,
how about this question:
meanwhile in 3rd and cruising at 2600 rpms... at what rpm will u hit FULL boost. Im running 1.3 bars and I also have a manual boost guage.. so its very easy for me to check.
I noticced that it takes time to hit full boost... ie. turbo lag.
Also, if Im in higher rpm.. I will hit 1.3 bars a lot faster.

 

KPV,

The proceedure would be to be cruising in the respective gear at 2600 rpm's. Then apply full throttle and determine how long ot takes to start producting boost. Yes, .01 bar. I mentioned third and fourth to get safe mid range power. Don't want this to be an unsafe excercise.

 

KPV,

The proceedure would be to be cruising in the respective gear at 2600 rpm's. Then apply full throttle and determine how long it takes to start producting boost. Yes, .01 bar. I mentioned third and fourth to get safe mid range power. Don't want this to be an unsafe excercise.

 

ebaker,

What gear were you in for those times?

 

MARKSKI,

Full boost may get a little dangerous. I don't want to go there. Besides, most turbo's spool up pretty fast once they start to spool. If this excercise works out well, we can try so others.

There are no winners or losers here. What it will tell you is what your car is best set up for.

 

I tried it in third and fourth, it didn't seem to make a difference.

 

i tried.... will post videos tomorrow... i get full boost of 1.2 /1.3 at 4200 rpms... crusing form a 2600 rpm in 3rd gear.

 

Guys,
I am trying to understand this. Call me thick.
What is so special about 0.1 bar on the Porsche boost gage? Obviously, it is the smallest unit of measurement on that particular gage, but why would that make it have any significance? Why not 0.01 or 0.05 or anything else for that matter? I realize that could be a superficial reference since we all have boost gages and it will give a rough determination as to when the car is starting to produce an intake manifold pressure greater than ambient. Reasoning please? Also, why does time from a lower pressure to realization of 0.1 bar define "lag"??? I would really like to understand this.

In my opinion, for whatever that is worth, it would make much more sense to use limit state testing. Here is my reasoning........
Each car's "package" is comprised of a unique group of components. These include turbos, air intakes, turbo hoses and piping as well as programming. In my case, running a GIAC based Stage 4 + R program, I will develop just over 1.2 bar (or about 18 psi of boost pressure).

My suggested test parameters would be as follows:

1. Drive on empty road with car in 3rd gear at 2,000 rpms with display set to boost pressure.
2. Let car equalize at that speed.
3. Mash throttle and press stopwatch at same instant.
4. press stopwatch when boost gage hits it predetermined maximum.

I feel this will yield better results. The main reasons are that turbo spool up is based on overcoming the inertia of the impeller, shaft and pump vanes as the exhaust flow increases. Each different turbo type will have different characteristics in this regard. If you look at the turbo impeller vanes, they are oddly shaped (read...of varying slope across their height). I believe this is to be a best compromise between low velocity and high velocity exhaust gases as the engine revs increase. That said, the time to full boost, as described above, will undoubtedly occur well below redline, thus allowing the car and its occupants to experience the acceleration advantages of a turbocharged engine. On the track, I routinely get on the gas and await the thrust. I stomp the throttle upon corner exit, set the car's rear wheels and await full boost. At that point, I ride the curve (metaphorically speaking) to the next shift.

 

Yes, turbos do lag, but they do offer some great advantages as well.
Personally, I prefer and enjoy making 6lbs boost at 2000rpms-7500rpms in my Lamborghini using dual eaton superchargers. Coming from a Stage IV Turbo X-50 to a supercharged Lamborghini Roadster was quite pleasing with the instant boost of the eaton superchargers. Ever wonder why a Ford GT, or the VERY HEAVY Mercedes SL65amg can rocket through the 1/4 mile faster than most modded turbos? It because these cars make instantaneous boost and have an extremely flat torque curve (they make power everywhere!).

Heck, I love both cars, but there is something to be said for instant boost.

 

on the other hand... a tt is 3.6liters and a lambo is 6.0 liters... it should produce a whole lot more TQ. not to mention that we haver this thing called PSM( I call it PMS).... that will always mess me up at the track.
I had a 98 roadster diablo... it was great... turbocharged must be awesome.
I dont think V12s or V10s supercharged are or even should be compared to a TT... these are simply different animals.
My lambo hit 67 MPH in 1st gear... my TT hits 35...not good for the 1/4 mile track.

 

Tell me more about this lambo. Year, Mods, etc... Thanks!