[Shotimes] Power adder discussion

[Ron Nottingham]

----- Original Message ----- 
From: "Ron Tyler" <rontyler@earthlink.net>
>
> On Thursday, October 2, 2003, at 12:57 PM, Ron Nottingham wrote:
>
> > <snip> Now, with many
> > turbo engines sporting around 9:1 CR (most early systems used 7.5:1 or
> > less!), and properly sized turbos, "turbo lag" is a non-issue, except
> > when
> > trying to pull from higher gears when the engine is out of the power
> > band.
>
> I agree that technology has come far enough to make a turbo street car
> perform with so little lag as to be a "non-issue" but
> the above statement does not stand true under REAL racing conditions...
> There will ALWAYS be SOME amount of lag.... Its a matter of how much...
> there are countless circumstances under racing conditions that NO
> amount of lag is desirable.

I have raced turbo cars under REAL racing conditions, both on the strip and
the track.  I will stand by my statement of a properly sized turbo along
with a realistic CR will produce no discernable lag and will produce more
torque at a lower rpm than an s/c'd car and even most small block v8's.
Now, if you go to a larger turbo and a lower CR to produce higher boost and
avoid detonation, yes there will be lag, and depending upon the powerband of
the engine and the gearing of the car, yes lag would be undesirable.

My previous 300zx turbos both had a torque peak of 2600 rpm (torque curve
was pretty flat all the way to 4500 rpm), and were producing 75% of max
boost at 2000 rpm (they were not stock, stock torque peak was 3400 rpm).
In this case, there was not any "turbo lag", except when I was cruising in
5th gear at 2k rpm and wanted instant power in 5th gear.  I did not have any
more hesitation to accelerate than I would have had in any other n/a car.
When racing, upshifts never fell below 2500 rpm, the engine was never off
boost and with proper use of BOV's and wastegates, boost pressure stayed
high and did not fall.

If you have turbo lag, it is a direct result of a turbo that is too large
and a CR that is too low.

Ron N. - Dalton, GA
90 SHO
89 325i
88 325
"It takes a man to suffer ignorance and smile"
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