Listers,
In the OLD days I used to run a 12.5 :1 small block chevy that never ever
pinged on pump gas. The effective cylinder pressure was 185 lbs. Cranking
with a roller tappet cam, small chamber head that were angle milled 120 - 0
on the exhaust side tapering to the intake side and a flat top 11:1 TRW
short skirt super stock pistons. The engine was FANTASTIC as it just would
not detonate. Which ever way I go to build compression in my Tiger 302 I
will try to avoid a pop-up piston. In the OLD days I ran it with pump gas
and no detonation with a Crane TR 242 with 104 degree lobe centerlines and
242 degrees duration as it was a symmetrical cam. The only thing that
affected the engine was a poorly curved distributor. As a result that is the
first thing done to any of my performance engines. So I just have a hard
time with anyone under 11.5:1 having detonation problems unless they are
using a cam that also fools the engine by slamming the valve shut early
changing the effective compression ratio to an engine that acts like it has
13:1. The reason for increasing compression is to take advantage of longer
cam timing duration's so that you can leave the valve open longer and still
squish it enough on a naturally aspirated engine to get all of the energy
out of the fuel used. If someone has 10.5:1 with a cam that is intended for
a 9.0:1 engine the engine is likely to have detonation problems unless they
retard the cam and close the intake valve later in the compression stroke
which kind of defeats the profile built into the cam for a given RPM range.
Hey we are back to talking about generating some heat for a change we will
worry about cooling it later!
Regards,
Tim Ronak
My 2 cents again!
-----Original Message-----
From: Theo Smit [mailto:TSMIT@isotel.com]
Sent: Thursday, January 20, 2000 5:18 PM
To: 'Doug Mallory'; Ronak, TP (Timothy);
'tigers@autox.team.net'
Subject: RE: Performance Tuning the Tiger
So there's a topic worthy of discussion: Assuming we're
using a mildly zoomy
cam (let's say the Ford Motorsport E303 or equivalent),
what's the maximum
compression ratio we can run if we're going to use street
gas (91 octane).
Assume the engine will use 38 degrees max timing advance.
Which heads are more susceptible to detonation?
Comments?
Theo
> -----Original Message-----
> From: Doug Mallory [SMTP:rdmallory@earthling.net]
> Sent: Thursday, January 20, 2000 5:01 PM
> To: Ronak, TP (Timothy); 'tigers@autox.team.net'
> Subject: Re: Performance Tuning the Tiger
>
> The only problem you will have is the same as my Tiger ...
>
> Getting gas. I am running 12:1 popups with 351 heads
(Don't Tell) getting
> 2-4mpg
> at $4.25 a gal.
>
> Doug
>
>
> At 09:13 AM 1/20/2000 -0600, Ronak, TP (Timothy) wrote:
> >Listers,
> >Based on the feedback most of everyone focused in on the
260 to 289
> >overbore. Others assumed that I would attempt this. Rest
assured all that
> I
> >am not going to attempt this as I will remove the
original 260 and save
> it
> >as it is becoming a rarity now. If I choose to increase
performance on my
> >tiger I will use something a little more plentiful and
build a higher
> >displacement unit.
> >Some general things I plan to do are to build a 10.5 :1
engine with a
> flat
> >top piston angle milled or twisted wedge heads with small
chambers, a
> >hydraulic roller cam, crower or carrillo rods, a billet
MSD distributor
> with
> >an MSD 6T and rev control under my performer RPM manifold
with a 650
> Holley
> >for now and potentially a manifold mounted fuel injection
system (like
> >Theo). None of this is covered in the book I primarily
purchased it for
> >nostalgia but I certainly appreciate everyone's concern
that I might
> >actually try some of the stuff in the book.
> >I sure like this list.
> >Best regards,
> >Tim Ronak
>
|