Ok, Here is a HYPOTHETICAL Scenerio, and by no means is an implication on any one or any tuning company, but just a question to satisfy my curiosity.


Say you took a Stock Porsche Turbo and got it DYNO'd - and the results were:

400RWHP (assuming front diff disengaged) and 400RWTQ


Then, say you did some modifications to it, and the Dyno results and Dyno Graph show about 150RWHP and 150RWTQ more....

Is it possible for the car, on the road, be a tad SLOWER? or FEEL SLower?

Could it be possible that the POWER CURVE can be changed to a point where, once you were powerful in 3rd gear, but now slower in 3rd, but more powerful in 4th and 5th?

Do Dyno's translate to real world ...on the road ?


Thanks,
Ryan

 

Short answer (although not a Guru) is NO. 150 extra TQ must push you deeper into the seat in any gear.

 

That is not correct, it is quite possible for a car to have more peak torque and more peak hp and make less power at other RPM's.

I am also not a "GURU" but if you have a very flat torque curve you can have a lot of area under the curve. A peaky engine can have less area under the curve and only generate more power at very high RPM's.

I have seen snowmobile engines that are tuned by various means that develop substantially more power at high RPM's but down low are complete dogs.

 

People forget about the curve and only concentrate on peak HP.

 

bigger turbos= more lag in 1st ,2nd, and 3rd- because they do not come on full boost.... but once 4th and 5th come in it should be over....
Sometimes if you run stock WGs and the boost falls off .1 or .2 bars because it cannot hold the pressure. So, for example, k24s should run 1.2 bars in 4th but most guys run 1.1 bars or 1 bar( it falls off).
I do not believe in dynos... they can be manipulated to ones liking....
Go to the track and check you MPH... maybe ET as well... the black dyno lies.
How come a 1000 rwhp(dynoed) viper runs only low 10s.... how come a 600 HP TT runs only 11.7s to 11.8s at best... and averages 11.9s. thast only .3s better then stock.

 

Umm, my 1000rwhp viper ran 8.35@178

 

My point was not to pick on vipers... the point is that alot of tuners(viper, evo, supra, and Porsche...) use dynos as means of selling kits.. and thats not always translated into results..
here is my own example:
I have an evo8 that ran 10.5 at 135 mph on 30psi. it dynod on this set up 500 awhp... then we tuned it on the dyno again and got another 140 awhp= 640 awhp total. Yet we went to the track and I ran only a 10.2 seconds at 138 mph.
SO why did we only gain .3 seconds and 3 mph with an extra 140 awhp ???
Dynos tell a story but not the whole story....

 

Large turboed cars may not have the increased "push" in your seat in the lower gears due to turbo lag. You may not make full power in 1st or even 2nd. They will generaly make less boost/power in the lower gears. That's truely the territory of the American cars with their normally aspirated or blown HP.... and maybe the 997TT

 

This is a good read.

http://www.germanmotorcars.com/Dyno_...0inertia_1.htm

A good way to see relavant HP is with a G-tech since the cars are actually in motion on a road with resistance. Here's a stock 515 HP Lamborghini Gallardo vs a stock 450 HP 996tt X50. Both runs are valid with correct 0 Gs base line starts.

The 11.8 1/4 is from a stock 996tt X50 with a bit over 5000 rpm launch. Shifts were in the .25 second range. The run had a density altitude of about 1200 ft and was performed immediately after cruising out of boost on the freeway for about 10 minutes. Engine intake temps were very good. I tested the Lamborghini in the same location, but with a density altitude of about 2500 ft.

 

This thread was a good read, although i knew the answer, OF COURSE a car can feel a bit slower, it shouldnt but there are many factors!

 

Taller 1st & 2nd gears in the GT700 seem to enable the car to dramatically improve acceleration. Big Bad Ben has done this to his car. If a higher RPM were also instituted, I feel the results would be even that much better. But then again, WTF do I know

 

What / is there a way to calculate and compare area under the curve? this would be a very meaningful method of comparing cars and tuning packages.

 

Calculus. Integrate the curve (or the integral that approximates the curve...like some 6th order polynomial).

 

So if I check into a Holiday Inn Express for a couple of nights I will be able to string this together with a datalog from my AX22?

 

I have a evo8 with shorter gears and can say that the car is faster..
actually, Im going to the track on the 13th of august... so Ill be able to compare... what happened to all the guys with the ax22 ? anyone still using this unit???