[DeTomaso] Cleveland HP limits

cengles at cox.net cengles at cox.net
Tue Jul 15 10:00:26 EDT 2014


Dear Boyd,

                 OK.....500 hp is certainly a safe limit for a sound 
stock Cleveland block.  Incrementally, as you go up, potential problems 
small and large also go up.  In my amateur opinion, I think that there 
may be some increased risk with stock rods--even polished and peened at 
those power levels.  A friend once told me that it wasn't the absolute 
power that was the problem, it was how long it would hold together.  I 
think that a street engine that sees max output occasionally and briefly 
is doable at those power levels, but carefree reliability is less than 
at lesser power levels.   What does your engine builder tell you?

                           Warmest regards,  Chuck Engles

On Mon, Jul 14, 2014 at 9:57 PM, Boyd Casey wrote:

  Chuck, I am working on a build using a sound 4 bolt main, forged 
crank, shot peened and polished rods , Ported A3 heads built with high 
quality roller rockers a springs, Forged flat top springs, Arp fasteners 
melling oil pump, 180 degree headers, a cust ground HR roller cam and 
lifters. And an IR efi system. The reason for my question is because the 
dynomation predicts HP in the 550- 600 range @ 6500 rpm. Someone said to 
me that they thought 500 hp was the safe limit for a stock Cleveland 
iron block. I have heard of stroked Cleveland iron blocks making over 
600 hp so was curious to know if there was an accepted HP limit that one 
would be advised not to exceed. ( Like piston speed) Not how much HP or 
torque CAN be made but how much can the block withstand (assuming you 
are using the best parts so that the block would fail before the 
rotating assembly or a valve something like one of the mains letting go 
or the engine exploding. I hope this makes my question more clear.

On Mon, Jul 14, 2014 at 10:30 PM, Charles Engles < cengles at cox.net 
<javascript:parent.wgMail.openComposeWindow('cengles at cox.net')> > wrote:
Dear Boyd,

          Oh, boy.   An opinion question.................

          See below.

"Greetings Pantera brethren ! Is there an accepted HP limit for a 
Cleveland four bolt main iron block at it's normal displacement? No 
 over bore, stock stroke, natural aspirated. Using heads , headers, cam, 
ignition, all the trick valve work , porting polishing, strongest 
possible rotating assembly.
Is there a limit that one should not exceed? 550hp, 575 hp, 600 hp 
higher?
If it is possible to reach  these HP numbers while not exceeding 7000 
rpm what is the DO NOT EXCEED LIMIT?"

  <javascript:parent.wgMail.openComposeWindow('cengles at cox.net')>
1)  Answer: it all depends on dozens and dozens of details.   Block 
quality, budget, application for street, track days or ORR or drag 
racing, carb v. efi., dollars, etc, etc.

2)  New question: Given a reasonable Cleveland block, reasonable 4V 
quench heads, stock rotating assembly, new pistons, new intake manifold 
and a reasonable budget (what does that mean?) what can you do?   Well, 
it depends.   It depends on the application.  It depends on the 
machinist and the engine builder.  I am not an engine expert, but I have 
built four engines and I am about to finish another one and I am making 
plans for the next one.   Facts: a rookie can build a 400 hp engine with 
stock block, crank, rods and heads plus after market bits.  Rpm max 
about 6000 before valve float.   More attention to detail can result in 
a 485 hp engine and a 6,500 rpm limit before valve float.  The current 
engine with the same formula but pushed a little harder with a lighter 
and more expensive valve train is expected to see 500 or so HP with a 
7000 rpm limit.   The cost goes up with HP and rpm limit.   The higher 
goal you set will require higher dollars.

3)  I expect that given solid lifters, an aggressive cam, high 
compression ratio, race gas, EFI and a relatively short functional life 
span numbers north of 550 hp and 7000 rpm can be obtained.

                     Warmest regards,  Chuck Engles

-------------- next part --------------
   Dear Boyd,

                   OK.....500 hp is certainly a safe limit for a sound
   stock Cleveland block.  Incrementally, as you go up, potential problems
   small and large also go up.  In my amateur opinion, I think that there
   may be some increased risk with stock rods--even polished and peened at
   those power levels.  A friend once told me that it wasn't the absolute
   power that was the problem, it was how long it would hold together.  I
   think that a street engine that sees max output occasionally and
   briefly  is doable at those power levels, but carefree reliability is
   less than at lesser power levels.   What does your engine builder tell
   you?

                             Warmest regards,  Chuck Engles

   On Mon, Jul 14, 2014 at 9:57 PM, Boyd Casey wrote:

    Chuck, I am working on a build using a sound 4 bolt main, forged
   crank, shot peened and polished rods , Ported A3 heads built with high
   quality roller rockers a springs, Forged flat top springs, Arp
   fasteners melling oil pump, 180 degree headers, a cust ground HR roller
   cam and lifters. And an IR efi system. The reason for my question is
   because the dynomation predicts HP in the 550- 600 range @ 6500 rpm.
   Someone said to me that they thought 500 hp was the safe limit for a
   stock Cleveland iron block. I have heard of stroked Cleveland iron
   blocks making over 600 hp so was curious to know if there was an
   accepted HP limit that one would be advised not to exceed. ( Like
   piston speed) Not how much HP or torque CAN be made but how much can
   the block withstand (assuming you are using the best parts so that the
   block would fail before the rotating assembly or a valve something like
   one of the mains letting go or the engine exploding. I hope this makes
   my question more clear.

   On Mon, Jul 14, 2014 at 10:30 PM, Charles Engles < [1]cengles at cox.net>
   wrote:

   Dear Boyd,

   A  A  A  A  A  Oh, boy. A  An opinion question.................

   A  A  A  A  A  See below.

   "Greetings Pantera brethren ! Is there an accepted HP limit for a
   Cleveland four bolt main iron block at it's normal displacement? No
   A over bore, stock stroke, natural aspirated. Using heads , headers,
   cam, ignition, all the trick valve work , porting polishing, strongest
   possible rotating assembly.

   Is there a limit that one should not exceed? 550hp, 575 hp, 600 hp
   higher?

   If it is possible to reach A these HP numbers while not exceeding 7000
   rpm what is the DO NOT EXCEED LIMIT?"

   1) A Answer: it all depends on dozens and dozens of details. A  Block
   quality, budget, application for street, track days or ORR or drag
   racing, carb v. efi., dollars, etc, etc.

   2) A New question: Given a reasonable Cleveland block, reasonable 4V
   quench heads, stock rotating assembly, new pistons, new intake manifold
   and a reasonable budget (what does that mean?) what can you do? A
   Well, it depends. A  It depends on the application. A It depends on the
   machinist and the engine builder. A I am not an engine expert, but I
   have built four engines and I am about to finish another one and I am
   making plans for the next one. A  Facts: a rookie can build a 400 hp
   engine with stock block, crank, rods and heads plus after market bits.
   A Rpm max about 6000 before valve float. A  More attention to detail
   can result in a 485 hp engine and a 6,500 rpm limit before valve float.
   A The current engine with the same formula but pushed a little harder
   with a lighter and more expensive valve train is expected to see 500 or
   so HP with a 7000 rpm limit. A  The cost goes up with HP and rpm limit.
   A  The higher goal you set will require higher dollars.

   3) A I expect that given solid lifters, an aggressive cam, high
   compression ratio, race gas, EFI and a relatively short functional life
   span numbers north of 550 hp and 7000 rpm can be obtained.

   A  A  A  A  A  A  A  A  A  A  A Warmest regards, A Chuck Engles

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