RE: WTB 272 Cam + comparison numbers

["Bruce Bell" <bbell04@ibm.net>]

The comparison numbers comparing stock, Schrick and Schrick + exhaust are at
the bottom of this post with little editorial.

> I rode in Bruce's car at Pikes peak and at 6,000 feet it was
> pulling MUCH
> stronger than my 4kq was.  Same with Ned Ritchie.  his
> Daughters car pulls
> much stronger as well.  Just keeps pulling right to 6,700
> RPM.

Yes, I understand Ned found another 200 rpm under the rev limiter. He tells
me that's about all you can get with a FPR hack or change as the ecu
apparently manipulates the signal to the control pressure regulator.

> I'm not sure
> I agree about the Exhaust.
> 	On my 4kq, replacing the 2.25" with a 2.5" exhaust with a Borla
> Muffler really make it pull stronger.  My 50-70 times
> dropped, as did my
> 0-60.  Before it would start to die before 6k RPM as do most
> 4kq's I've
> driven.  Afterward it charged right past 6k.  There was a
> slight hiccup
> int he poer curve around 4,800 for a brief second (like 1/4 second if
> that) but it pulled much stronger.

We could be comparing apples and oranges as far as exhaust goes. Mine is an
Urq SS cat back with a short glass pack for a center muffler and a cheap,
most defiantly not Borla quality, rear turbo style muffler. If you have one
of the Borla universal mufflers for a normally aspirated motor then you are
way ahead of me here.

> 	Anyhow, what info do you have to counter this.  I'd love to see
> those graphs.  Cyclic is one thing, but f the lows in the
> cycle are the
> same as the flat curve of the OEm system and the highs give more power
> then 2.5" will be faster.  At any rate, torque may be
> effected a bit.

Decide for yourself. To really see the picture graph these numbers in Excel.
The first two column are from my review of the Schrick cam and the third is
after I installed the exhaust. The testing with the exhaust was done at an
altitude considerably lower than the 5300' where I live, so I used the
correction factors from SAE J1349 to standardize the results to 5300'

     rpm   Stock   +Schrick +Exhaust
    1250    69.7    59.6    63.3
    1750    76.1    67.9    71.7
    2250    77.9    72.3    67.6
    2750    79.3    77.0    74.4
    3250    79.3    79.3    82.7
    3750    79.3    79.3    74.4
    4250    79.3    80.2    72.1
    4750    77.4    80.2    71.3
    5250    73.9    79.7    89.6
    5750    58.8    77.4    77.3
    6250    38.7    66.2    60.4
Total      789.5   819.1   804.8

And yes, that surge really is there at 5250 with the exhaust and it makes
the dip at 4800 all the more obvious. (I noted you observed it too). I think
this shows the value of having a properly tuned exhaust. Mind you I never,
certainly hope not, said 2.5" exhaust systems are bad. Just bigger and freer
flowing aren't always better with a NA motor.

Bruce