Strength Of Factory Blocks
10-16-2003, 01:27 PM
#11
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OK apparently there is a graph of what you are asking on page 454 of John Heywood's book "Internal Combustion Engine Fundamentals". We should have a copy of it at the shop. So I'll take a look tonight. They are probably for non-turbo piston engines though.
10-16-2003, 01:31 PM
#12
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Originally Posted by j9fd3s' date='Oct 16 2003, 10:11 AM
ah ok, so you know how fc's always have 1 borken engine mount? and its always the same one? i think when you drop the clutch it tries to twist the motor, too much twist = broken rear plate.
mike
mike
The engine I was referring to earlier that busted the rear plate was already in motion, though. I've never heard of it happening on clutch dumps.
B
10-16-2003, 01:41 PM
#13
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Originally Posted by BDC' date='Oct 16 2003, 10:31 AM
[quote name='j9fd3s' date='Oct 16 2003, 10:11 AM'] ah ok, so you know how fc's always have 1 borken engine mount? and its always the same one? i think when you drop the clutch it tries to twist the motor, too much twist = broken rear plate.
mike
mike
The engine I was referring to earlier that busted the rear plate was already in motion, though. I've never heard of it happening on clutch dumps.
B [/quote]
hmmm, good point.
mike
10-16-2003, 07:56 PM
#14
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think when you drop the clutch it tries to twist the motor, too much twist = broken rear plate.
I think we're on the money here. I too have seen amazing power from S4 motors that are still going, and the same power from S4 motors which have cracked that dowel area very quickly.
The difference between the cars has been the style of driving. The ones that break are much more aggressively driven, sidestepped clutches at 5000 revs, on-off type throttle control, and also coverted to front mount (in 1st gen RX7's).
This all leads to much greater twisting shock on the engine which I believe is the main cause for the break. If you want to make reliable power in a S4 motor, and do lots of drag type launches, that rear dowel area must be strengthened either by welding (not the best option imo), extra dowels added to the motor, or replace the plates with S5 or later plates. Some older Cosmo plates also have the strengthening around the dowel hole.
10-16-2003, 10:15 PM
#15
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Well, I've broke like 3 FULLY built Pineapple series 4 motors (1 in the rear dowl and 1 in the front). I know that equals 2, but the last one has yet to be determined. The rear rotor is making a clanking sound on the housing, so I think it may be a stationary gear. NONE were from launches just BOOST SPIKE (damm std wastegate 
) 24 psi on pump fuel = detonation.
10-17-2003, 07:56 AM
#19
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The book I mentioned wasn't down at the shop. Sorry I couldn't come up with numbers.
But a friend of mine brought up the point that there is only so much energy available because of the fuel. So assuming that you are getting a complete burn in your normal combustion cycle, the max chamber pressure should be the same as it is when it auto-ignites (detonation). The difference is that the auto-ignition will have a very rapid spike to that pressure, and the "normal" cycle will have a (relatively) longer build up to that pressure.
That's just talk though. Data from the book could tell us something else.
But a friend of mine brought up the point that there is only so much energy available because of the fuel. So assuming that you are getting a complete burn in your normal combustion cycle, the max chamber pressure should be the same as it is when it auto-ignites (detonation). The difference is that the auto-ignition will have a very rapid spike to that pressure, and the "normal" cycle will have a (relatively) longer build up to that pressure.
That's just talk though. Data from the book could tell us something else.
10-17-2003, 09:56 AM
#20
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Originally Posted by j9fd3s' date='Oct 16 2003, 10:11 AM
ah ok, so you know how fc's always have 1 borken engine mount? and its always the same one? i think when you drop the clutch it tries to twist the motor, too much twist = broken rear plate.
mike
mike
Well we are now using solid motor mounts on our cars (Mine and 87GTRs)