Alex,
Based on the calculation the net dome volume (Dome volume - Valve relief if
in fact TRW calculated it right then the Dome volume is 3.658cc. When you
run it through the numbers if in fact the dart heads have 64c then with the
same dome the number I get is 10.75:1 based on a 100 thous. Compressed head
gasket and zero deck height, but if the deck height is 10 thous or if the
valves are really sunk or dished then it could be as low as 10.71:1 but of
course that assumes that the numbers work and are accurate. No big one but
that is a really nice result and with the right cam should give you around
195-210 lbs cylinder pressure. You don't want any more as you will just
waste the energy trying to compress the charge and build too much heat. All
you need to ignite and fully burn pump gas to my knowledge is 190lbs.
I did not bother to recalculate the over bore assuming that if you 12.5:1
pistons that are 60 over then they should 12.5: for a 60 over engine, as
that would just increase the resulting compression given that the ending
volume stays constant but the swept volume increases.
Best regards
Tim Ronak
PS: I am in Cancun right now and I just got back from jet-skiing on the
Ocean so I am plenty warm.... I really appreciate the concern. BUT! I sure
hope Theo is not too cold.
-----Original Message-----
From: Alex MacLaurin [mailto:Alex_MacLaurin@telus.net]
Sent: Monday, January 24, 2000 3:44 PM
To: Ronak, TP (Timothy)
Subject: Re: Performance Tuning the Tiger
HI Tim-Thanks for the calculation but I've inadvertantly
mislead you, do to
my own bad memory.The TRW pistons are domed and were rated
at 12.5:1 for a
standard 289 chamber of 54.5 cc. I had the motor built with
351 Windsor
heads of 60.4cc and then subsequently built again with the
same pistons and
dart heads with 64cc chambers.I don't know what the dome
volume of the
piston is. Tom Hall figures I"m running about 10.3:1 with
the current
setup.Hope its not to cold in Calgary for you. ALEX
----- Original Message -----
From: Ronak, TP (Timothy) <Timothy.P.Ronak@akzo-nobel.com>
To: 'Alex MacLaurin' <Alex_MacLaurin@telus.net>
Cc: 'Tiger News Group List' <tigers@autox.team.net>
Sent: Monday, January 24, 2000 5:16 AM
Subject: RE: Performance Tuning the Tiger
> Alex,
> OK Bore on a 289 = 4.0 + .060 = 4.060
> Stroke on a 289 = 2.87" or 73mm or 7.3 cm
> =(4.060/2) squared X pi X 2.87"=swept volume
> in metric (10.3124cm/2)squared X (22/7) X 7.2898cm
> =swept volume 609.0684cc
> If you have a piston arrangement that yields around 12.5:1
ratio with a
48cc
> head then the following must be true:
> The piston is flat with around 2 cc valve reliefs
> The chamber is 48cc with the valves you are using and they
are not too
sunk.
> The compressed gasket is .010 thick
> The deck height is 0"
> The Bore is 4.060
> The total Final compressed area is 52.12235 including
gasket volume
> And the Total volume at piston BDC is 52.12235 +
609.115657 = 661.238012
> This arrangement yields 12.6862:1 Compression
>
> Keeping everything else constant and just changing your
combo to the Dart
> heads at 64CC yields a Compression ratio of 9.94149:1 a
really nice ratio.
>
> The 54cc heads give 11.47988:1
>
> This is assuming a flat piston as I would have to
recalculate if the
piston
> has a dome.
>
> I hope this fully answers your question, but if not I did
a quickie
> spreadsheet if you want it.
>
> I am out of town for the week so don't expect a quick
response.
>
> Best regards,
>
> Tim Ronak
> B382000680
>
> -----Original Message-----
> From: Alex MacLaurin [mailto:Alex_MacLaurin@telus.net]
> Sent: Friday, January 21, 2000 3:04 PM
> To: Ronak, TP (Timothy)
> Subject: Re: Performance Tuning the Tiger
>
> Tim- My motor is .060 over 289 that has 12.5:1{with I
think
> 48cc 289 head]
> forged TRW pistons. the motor was originally built with
54cc
> 351 heads that
> were changed to 64cc dart heads. The motor pulled a
> corrected 319.3 hp to the
> wheels in November and have never had a problem using 94
> octane pump gas.
> Thanks again Alex
>
> ----- Original Message -----
> From: Ronak, TP (Timothy) <Timothy.P.Ronak@akzo-nobel.com>
> To: 'Doug Mallory' <rdmallory@earthling.net>; Ronak, TP
> (Timothy)
> <Timothy.P.Ronak@akzo-nobel.com>; 'Alex MacLaurin'
> <Alex_MacLaurin@telus.net>; Ronak, TP (Timothy)
> <Timothy.P.Ronak@akzo-nobel.com>; 'Bob Palmer'
> <rpalmer@ames.ucsd.edu>
> Cc: 'Tiger News Group List' <tigers@autox.team.net>
> Sent: Friday, January 21, 2000 1:15 PM
> Subject: RE: Performance Tuning the Tiger
>
>
> > Alex,
> > Theo pointed out that I did not answer the question!!!
> Figures he would
> zing
> > me on that.
> > To do the calculation give me the bore size of you
engine,
> the stroke and
> > the piston configuration, we can make some assumptions
by
> working
> > backwards. i.e.: if you have 11:1 pistons with your 54cc
> heads if we know
> the
> > swept volume we can tell you how much the 64 cc heads
will
> drop
> compression
> > relative to your cubic inches.
> > Regards,
> > Tim
> >
> > -----Original Message-----
> > From: Doug Mallory [mailto:rdmallory@earthling.net]
> > Sent: Friday, January 21, 2000 1:53 PM
> > To: Ronak, TP (Timothy); 'Alex MacLaurin'; Ronak, TP
> > (Timothy); 'Bob Palmer'
> > Cc: 'Tiger News Group List'
> > Subject: RE: Performance Tuning the Tiger
> >
> > Well stated ! That was a collage course in two
paragraphs.
> >
> > Rule of thumb was for every 1lb before ignition you get
> > 10lbs after. That
> > is why ignition timing is more critical when you start
> > adding compression.
> >
> > Doug
> >
> >
> >
> > At 02:08 PM 1/21/00 -0600, Ronak, TP (Timothy) wrote:
> > >Alex,
> > >To determine compression it depends on whether you talk
> > about static
> > >compression or Dynamic compression.
> > >Static Compression
> > > i.e.: the compression based on the swept volume of
the
> > cylinder bore that
> > >is displaced by the engine as it moves the piston. You
> > simply take the bore
> > >say 4" an put it into the formula for area of a
cylinder
> > lets presume the
> > >stroke is say 3.48 (Chevy 350 sorry guys) for
> (4/2)squared
> > X pi X Length of
> > >the cylinder 3.48" for 43.7485 cubic inches or X 8 =
> > 349.988 ci (small block
> > >350) . or in Metric 4" = 10.16 cm and 3.48" = 8.8392
> cm
> > the formula then
> > >gives roughly 25.8064cm X 3.14285714285 X 8.8392 =
> > 716.9106 cc.
> > >
> > >If we assume zero deck height no valve relief or dome
and
> > no gasket the
> > >ratio would be ((716.9106 swept volume + 54cc Head
> > volume)/54cc) : 1 or
> > >13.276:1 compression.
> > >
> > >To do your computation we would need Bore size, dome
and
> > piston valve
> > >relief, volume and thickness of the compressed head
> gasket
> > and piston to
> > >deck height.
> > >
> > >That gives you static compression.
> > >
> > >Dynamic compression
> > >What you really want is dynamic compression and get it
> > around 195lbs of
> > >compression for pump gas. And you can do this with a
10:1
> > or a 11:1 or a
> > >12:1 or a 13:1 compression ratio depending on when you
> > choose to close the
> > >intake valve in relation to the position of the piston
in
> > the bore. It
> > >depends what you plan to use the engine for but I have
> seen
> > 10.5:1 motors
> > >perform significantly better than 11.8:1 motors because
> the
> > produced more
> > >cranking cylinder pressure.
> > >
> > >I hope that helps,
> > >Tim Ronak
> > >B382000680
> > >A Canadian forced to stay indoors while it is cold out.
> > >
> > >
> > > -----Original Message-----
> > > From: Alex MacLaurin
> > [mailto:Alex_MacLaurin@telus.net]
> > > Sent: Friday, January 21, 2000 12:11
> PM
> > > To: Ronak, TP (Timothy); 'Bob
> Palmer'
> > > Cc: 'Tiger News Group List'
> > > Subject: Re: Performance Tuning
> the
> > Tiger
> > >
> > > With all this talk about compression,
I
> > have a question: if a
> > >motor has 11:1
> > > compression with a 54cc chamber and
all
> > variables stay the
> > >same, how much
> > > compression does the engine have with
a
> > 64cc chamber?
> > >
> > >
> > > ----- Original Message -----
> > > From: Ronak, TP (Timothy)
> > <Timothy.P.Ronak@akzo-nobel.com>
> > > To: 'Bob Palmer'
<rpalmer@ames.ucsd.edu>
> > > Cc: 'Tiger News Group List'
> > <tigers@autox.team.net>
> > > Sent: Friday, January 21, 2000 10:14
AM
> > > Subject: RE: Performance Tuning the
> Tiger
> > >
> > >
> > > > Bob,
> > > > 195 ....so I was told ... is about
the
> > optimal pressure to
> > >avoid excessive
> > > > heat generation on the compression
> > stroke and not use too
> > >much power to
> > > > compress the next charge when
running
> > pump gas. If you
> > >were to optimally
> > > > tune your engine you could probably
> > retard the cam 1
> > >degree close the
> > > > intakes a little later drop the
> cylinder
> > pressure for an
> > >average of 195
> > > > (190-200 range between cylinders)
and
> > get a little more
> > >power out and it
> > > > might even run slightly cooler. IMHO
> > This explains why you
> > >do not have
> > > > detonation. But didn't you run the
car
> > at 60 degrees
> > >advance. I hope now
> > > you
> > > > are around 36-38 Total at 5000+ RPM.
I
> > hope someday I can
> > >go for a ride.
> > > > Regards,
> > > > Tim Ronak
> > > >
> > > > -----Original Message-----
> > > > From: Bob Palmer
> > [mailto:rpalmer@ames.ucsd.edu]
> > > > Sent: Friday, January 21, 2000 8:57
AM
> > > > To: Ronak, TP (Timothy);
> > MWood24020@aol.com;
> > > > TSMIT@isotel.com;
> > rdmallory@earthling.net; Ronak, Timothy
> > >P;
> > > > tigers@autox.team.net
> > > > Subject: RE: Performance Tuning the
> > Tiger
> > > >
> > > > Tim,
> > > >
> > > > After you guys taught me the proper
> way
> > to do a
> > >compression
> > > > test (plugs
> > > > pulled, WOT) I get 195-205 psig
> > depending on which
> > >cylinder
> > > > and which day.
> > > > I'm at sea level here, but of course
> > that doesn't affect
> > > > psig, just psia.
> > > >
> > > > Bob
> > > >
> > > > At 07:57 AM 1/21/00 -0600, Ronak, TP
> > (Timothy) wrote:
> > > > >Bob,
> > > > >I have to agree with you about the
> > effect removing and
> > > > sharp spots from the
> > > > >combustion area will have on
> > detonation. The key to
> > > > avoiding the excessive
> > > > >pressures is by changing where the
> > Intake valve closes in
> > > > relation to the
> > > > >piston traveling up on the
> compression
> > stroke. What is
> > >your
> > > > cylinder
> > > > >pressure warm with all of the plugs
> out
> > ... or have you
> > > > tested it? The
> > > > >method I will use on y 302 will be
to
> > chose the desired
> > >cam
> > > > profile and then
> > > > >increase compression (or advance
the
> > cam) until I obtain
> > > > about 195 lbs
> > > > >cylinder pressure cranking. My
> > experience is similar to
> > > > yours in that
> > > > >compression is fine provided that
the
> > combination once
> > > > assembled gives you a
> > > > >usable cylinder pressure. It may be
> > that the guy who has
> > >to
> > > > run race gas
> > > > >needs to install a cam with a
little
> > more overlap or one
> > > > that closes the
> > > > >intake valve a little later
reducing
> > the amount of
> > >cylinder
> > > > pressure the
> > > > >piston can build. I do know that
back
> > in the race car
> > >days
> > > > we had an engine
> > > > >that was 14:1 (remember that car
Theo
> > .. it was blue and
> > > > yellow) it made
> > > > >over 220 cranking cylinder pressure
> and
> > we had to run
> > >C-14
> > > > and methanol in a
> > > > >15% and 85% ratio respectively or
it
> > detonated like
> > >crazy.
> > > > >My 2 cents too,
> > > > >Tim Ronak
> > > > >B382000680
> > > > >PS: It is amazing how a well placed
> > email gets us back on
> > > > the performance
> > > > >topic....YEEHaaaww!
> > > >
> > > > Robert L. Palmer
> > > > UCSD, Dept. of AMES
> > > > 619-822-1037 (o)
> > > > 760-599-9927 (h)
> > > > rpalmer@ucsd.edu
> > > > rpalmer@cts.com
> > > >
> >
> >
>
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