[DeTomaso] Cam selection - corrected

Sun May 23 17:33:07 EDT 2010

Hey - **thank you** Dan.
Monday I'll find out what the Bullet delivery is.
I'm trying to make it to the Vancouver Italian car show on Father's day.
I like those ramp numbers better (49 & 50 I think) and the valve spring 
requirement should be moderate.
I'm just plugging your numbers into my spreadsheet now.
Quite a way to spend your weekend.
Thanks again
dave

Daniel C Jones wrote:
> Simulation of several cams for Dave Londry:
>
> I used the flow numbers from the heads Dave McLain ported for Glen
> Hartog (322 CFM @ 0.6).
> Predicted numbers may be optimistic because they do not reflect the
> area chage from small
> 2V intake to 4V head nor the the unusual collector of the Hall
> headers.  Also the 351C
> dyno mule results have been 10 to 15 HP or so optimistic, 30 ft-lbs
> optimistic.  Assuming
> the typical flat top TRW L2379F piston, 10.8:1 would mean the heads
> and/or block was milled.
> 10.25 is more likely with unmilled block and heads.  I would want at
> least 225 degrees intake
> duration with 10.8:1 compression.  Note that the simulation gives a
> better approximation when
> simulating canted valve heads with 2 degrees tighter LSA.  That is a
> cam with 110 LSA in the
> simulation is really 108 degrees in the actual cam.  Using you Comp
> Cams links, here are the
> results:
>
> 275DEH as 110 LSA (closer to 108 LSA in canted valve head)
>  447 5500 148 at 2000
>  470 4000
>
> 275DEH as 112 LSA (mimics 110 LSA in canted valve head)
>  436 6000
>  466 4000
>
> XE262H as 110 LSA
>  429 6000
>  466 4000
>
> 270H as 110 LSA
>  431 5500
>  474 4000
>
> XE274H as 110 LSA
>  468 6000  147 at 2000
>  476 4500
>  274/286 230/236 0.562/0.565 110 LSA
>
> 280H
>  452 6000
>  471 4500
>  280/280 230/230 0.530/0.530 110 LSA 60 degrees seat overlap, (10 deg @ 0.050)
>
> XE284H as 110 LSA
>  486 HP @ 6000 RPM
>  467 ft-lbs @ 4500 RPM
>  284/296 240/246 0.584/0.588
>
> The XE284H is a fair bit of cam for a 351C and has a 3.34 ramp rate
> which is fairly aggressive
> so may be a bit noisy.
>
> I didn't run an optimization but I did pick a couple of lobes from the
> Bullet catalog that I
> thought might work well for you.   Bullet's custom flat tappets are
> $172.50 versus $137.76 to
> $146.58 for the catalog grinds from Comp's store.
>
> Bullet custom
>  277/285 228/235 0.581/0.541 110 LSA using lobes:
>   HF277/335   277  228  142   .3350  .580 .000  CRA
>   HF285/312   285  235  147   .3125  .541 .000  CRS
>  473 HP @ 6000
>  475 ft-lbs @ 4500
>
> Similar in overlap to the XE274H but better power.  Running an
> optimization on this should
> improve upon this.
>
> Dan Jones
>
> On Sat, May 22, 2010 at 12:25 AM, Dave Londry <davel at emspace.com> wrote:
>   
>> Sorry - I had the rpm off by one column
>>
>> Dan has me in the queue for a run,
>>  but in the meantime I've been running CompCams CamQuest simulator.
>> I doubt that the absolute numbers are good, but it should be good for
>> comparison.
>> Using this for input
>> ==========================================
>> = 0.030 overbore & stock crank
>> = 10.8:1  & 94 Octane
>> = 4V-CC heads, ported, polished and matched, but no port-stuffers.
>> = flat tappet & hydraulic lifters
>> = Hall big bores & ANSAs which I intend to core out
>> = Performer 2665 intake which I plan to replace with an AirGap
>> = 800cfm Thunder (I also have a 600 Performer but the 800 seemed fine)
>> = MSD 6AL
>> ============================================
>> The "best" choice was 275DEH
>>                         Dur at 0.050  Dur.  Ramp    Lift
>>        HP  RPM  FTP RPM   I   E   I   E  I  E  I     E     Spring#
>>  275DEH 517 6500 468 4500 219 232 275 285 56 53 0.515 0.541   293
>>
>> It was attractive because of the slow ramp and low spring requirement
>> Having a wiped lobe and short lifter kind of sensitizes you to those things.
>>
>> dave
>>
>>
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