Slant Six Forum :: I play with Desktop Dyno too much...

:
: That's correct, it has no idea what the
: mechanical limits of the engine are. It has
: no way of knowing whether the engine would
: go into valve float, or if a heavier
: reciprocating assembly might sap power. It's
: an "airflow-only" model, assuming
: optimal fuel distribution and spark timing.
: Also, I didn't use any hard data about slant
: six heads or manifolds - Desktop Dyno
: estimates the head flow data from valve size
: and head type. The program probably
: shouldn't claim VE numbers with four
: significant figures, but I'll show them
: anyway.
:
: Here are the combinations I've tried. I'll give
: the peak hp and torque numbers for 170, 198,
: and 225 inch combinations along with the RPM
: where they happen and the VE at that RPM.
: Since Desktop Dyno can also predict the
: optimum stroke length for a given
: combination, I'll see what that combination
: would be if I could get a stroker crank for
: the motor, too. Each engine will have
: everything held the same except stroke. If
: you need more info, I can get all sorts of
: things from the program - complete hp and
: torque curves, volumetric efficiency plots,
: cylinder pressure graphs, you name it.
:
: First one's a turbo combination similar to what
: I plan to eventually run in my '66 Dart with
: the original 225. I don't have the ported
: head or cam, and I'd want to rebuild it with
: forged pistons, but the turbo setup's
: getting installed on it at the moment.
:
: Cylinder heads: Pocket ported with 1.70"
: intake and 1.44" exhaust valves.
: Compression: 8.4:1
: Intake: Four barrel Holley, Rajay 300B turbo (I
: couldn't find a compressor map for the turbo
: I have, but this one seems to be sized for
: similar engines), 30% efficient air to air
: intercooler. The total flow ( not carb size
: in this case, but flow through the turbine
: inlet) is 600 CFM.
: Exhaust: Very free flowing muffler such as a
: DynoMax Ultraflow, or open exhaust.
: Cam: Mopar Performance "17 second"
: cam - 0.436" lift, 244 degree duration.
:
: Results: 170: 320 hp @ 6000 RPM / 117% VE, 320
: lb-ft @ 5000 RPM / 123.6% VE.
: 198: 317 hp @ 5500 RPM / 112.3% VE, 358 lb-ft @
: 4000 RPM / 117.6% VE
: 225: 314 hp @ 5000 RPM / 109.7% VE, 400 lb-ft @
: 3500 RPM / 114.9% VE.
:
: Optimum stroke: 2.56", 140 cubic inches
: (!)
: 327 hp @ 7500 RPM / 117.3% VE, 269 lb-ft @ 5500
: RPM / 124.3% VE
:
: Second combination is a super low buck effort,
: where the only mods are a decent muffler,
: Super Six, and a Clifford 276 degree /
: 0.464" lift cam. And, of course,
: getting the jetting and spark advance
: exactly right.
:
: Results: 170: 170 hp @ 6000 RPM / 81.1% VE, 166
: hp @ 4500 RPM / 79.7% VE
: 198: 170 hp @ 5500 RPM / 78.2% VE, 183 lb-ft @
: 4000 RPM / 76.1% VE
: 225: 164 hp @ 5500 RPM / 74.8% VE, 199 lb-ft 2
: 3500 RPM / 72.4% VE
:
: Optimized: 3.41" stroke / 186 cid, 171 hp
: @ 5500 RPM / 80.4% VE, 175 lb-ft @ 4000 RPM
: / 76.5% VE
:
: Last one's a naturally aspirated all out race
: motor.
:
: Cylinder head: Pocket ported with 1.74"
: intake and 1.44" exhaust valves.
: Compression ratio: 10.0:1.
: Induction: 500 CFM four barrel Holley on a
: Hyper Pak or other four barrel manifold.
: Exhaust: Dual headers with no mufflers.
: Camshaft: Clifford dual pattern, 290 degree /
: 0.530" intake, 300 degree / 0.515"
: exhaust.
:
: Results: 170: 303 hp @ 7500 RPM / 101.3% VE,
: 229 lb-ft @ 6000 RPM / 101.1% VE
: 198: 306 hp @ 7500 RPM / 96.0% VE, 250 lb-ft @
: 5500 RPM / 97.0% VE
: 225: 300 hp @ 7000 RPM / 93.3% VE, 267 lb-ft @
: 5000 RPM / 92.9% VE
:
: Optimized: 3.45" stroke, 188 cid
: 307 hp @ 7500 RPM / 98.0% VE, 242 lb-ft @ 6000
: RPM / 99.7% VE
:
: Kinda surprising results, they usually seem to
: suggest that the 170 or 198 would be a
: better choice. The first one where the
: computer suggested building a 2.3 liter
: slant six may be suffering from a mismatched
: turbo, since the original idea was for
: maximum torque and I had it optimized for
: power.

Author:	Matt Cramer [ Wed Aug 07, 2002 7:11 pm ]
Post subject:	I play with Desktop Dyno too much...
Sometimes I've been toying around with various combinations on Desktop Dyno when I have too much time on my hands. I've noticed a somewhat surprising trend, though. It seems like with many of the combinations I try - whether it's a Super Six and mild cam, turbo buildup with Mopar Performance's "17 second" cam (definitely not 17 seconds with 8 psi of intercooled boost!), or a rev it to the moon creation with a Hyper Pak and all out race cam, the power level is virtually unchanged whether it's a 170 or 225. The power's at different RPM, of course, and the torque curves don't look the same, but the extra 55 inches don't seem to boost power. Sometimes a 198 turns out to make more power than either one, to boot. Is this a case of equal airflow capacity meaning equal power? Or is Desktop Dyno just confused? Since I don't have much practical experience with building heavily tweaked /6's, can any of the gurus have anything to offer to confirm or deny these predictions? supersixman@hotmail.com

Author:	james longhurst [ Thu Aug 08, 2002 7:45 am ]
Post subject:	Re: I play with Desktop Dyno too much...
Quote: : Sometimes I've been toying around with various : combinations on Desktop Dyno when I have too : much time on my hands. I've noticed a : somewhat surprising trend, though. It seems : like with many of the combinations I try - : whether it's a Super Six and mild cam, turbo : buildup with Mopar Performance's "17 : second" cam (definitely not 17 seconds : with 8 psi of intercooled boost!), or a rev : it to the moon creation with a Hyper Pak and : all out race cam, the power level is : virtually unchanged whether it's a 170 or : 225. The power's at different RPM, of : course, and the torque curves don't look the : same, but the extra 55 inches don't seem to : boost power. Sometimes a 198 turns out to : make more power than either one, to boot. : : Is this a case of equal airflow capacity : meaning equal power? Or is Desktop Dyno just : confused? Since I don't have much practical : experience with building heavily tweaked : /6's, can any of the gurus have anything to : offer to confirm or deny these predictions? i once read on a slant page somewhere on the web that a 170 would ultimately make the same power as a 225. i think it was an old chrysler engineer who worked on the hyper pak program back in the early '60s. while i think that may be true, i also believe that it would take two different combinations. -james ludite13@cs.com

Author:	Doc. [ Thu Aug 08, 2002 9:52 am ]
Post subject:	Re: Desktop Dyno Output
Quote: : . . . the power level is : virtually unchanged whether it's a 170 or : 225. The power output at different RPMs and : the torque curves don't look the : same, but the extra 55 inches don't seem to : boost power. Sometimes a 198 turns out to : make more power than the 170 or 225! : : Is this a case of equal airflow capacity : meaning equal power? Or is Desktop Dyno just : confused? Since I don't have much practical : experience with building heavily tweaked : /6's, can any of the gurus have anything to : offer to confirm or deny these predictions? An inturnal combustion engine is basically an air pump and the desktop formulas treat it that way but we also know that there are many other factors which influance the output of an engine. Without knowing all the formulas and factors being used in the D. Dyno program, it's hard to say where the "over-simplication" is comming from. I would think that the program does little to consider the practical RPM limits if the parts. (do you input the weight of the crank, pistons, con rods etc?) Head flow and wet intake manifold dynamics such as even fuel distribution, harmonic / reversion / ram effects at different RPMs also has an influance that is hard to get defined in these software programs. It comes down to how accurate the program can get to accutate cylinder pressers and volumeteic efficiency numbers. Each engine design is different, each of our Slant engines is different because of the influance the stroke change has. (I would say that 55 cubes of bore change would be easer to model and accuratly adjust for then 55 cubes of stroke change) OK, what's all this really mean in "plain talk"?? (Please get us some D.Dyno output info, at what RPM does D.Dyno say a 170 = a 198? at what RPM does a 198 = a 225, spinning at 5500 RPM, all other parts / things being equal?) Let's say you need to spin a 170 to 8000 to make equivalent power of a 225 at 5500 RPM. How easy is it to get the VE of the 170 maximised at that RPM? Are there parts and knowledge available to support that? (cam profile, con. rods, intake manifold, etc) Will this engine be dependable operating at such a high RPM? I need to stop here, I would be interested is seeing some basic D.Dyno output estimates and hear some other thoughts on this topic. (this is cool stuff, I love chasing that "magic combo"!!) DD

Author:	Matt Cramer [ Thu Aug 08, 2002 3:19 pm ]
Post subject:	Further details and specs of virtual engines
Quote: : I would think that the program does little to : consider the practical RPM limits if the : parts. (do you input the weight of the : crank, pistons, con rods etc?) That's correct, it has no idea what the mechanical limits of the engine are. It has no way of knowing whether the engine would go into valve float, or if a heavier reciprocating assembly might sap power. It's an "airflow-only" model, assuming optimal fuel distribution and spark timing. Also, I didn't use any hard data about slant six heads or manifolds - Desktop Dyno estimates the head flow data from valve size and head type. The program probably shouldn't claim VE numbers with four significant figures, but I'll show them anyway. Here are the combinations I've tried. I'll give the peak hp and torque numbers for 170, 198, and 225 inch combinations along with the RPM where they happen and the VE at that RPM. Since Desktop Dyno can also predict the optimum stroke length for a given combination, I'll see what that combination would be if I could get a stroker crank for the motor, too. Each engine will have everything held the same except stroke. If you need more info, I can get all sorts of things from the program - complete hp and torque curves, volumetric efficiency plots, cylinder pressure graphs, you name it. First one's a turbo combination similar to what I plan to eventually run in my '66 Dart with the original 225. I don't have the ported head or cam, and I'd want to rebuild it with forged pistons, but the turbo setup's getting installed on it at the moment. Cylinder heads: Pocket ported with 1.70" intake and 1.44" exhaust valves. Compression: 8.4:1 Intake: Four barrel Holley, Rajay 300B turbo (I couldn't find a compressor map for the turbo I have, but this one seems to be sized for similar engines), 30% efficient air to air intercooler. The total flow ( not carb size in this case, but flow through the turbine inlet) is 600 CFM. Exhaust: Very free flowing muffler such as a DynoMax Ultraflow, or open exhaust. Cam: Mopar Performance "17 second" cam - 0.436" lift, 244 degree duration. Results: 170: 320 hp @ 6000 RPM / 117% VE, 320 lb-ft @ 5000 RPM / 123.6% VE. 198: 317 hp @ 5500 RPM / 112.3% VE, 358 lb-ft @ 4000 RPM / 117.6% VE 225: 314 hp @ 5000 RPM / 109.7% VE, 400 lb-ft @ 3500 RPM / 114.9% VE. Optimum stroke: 2.56", 140 cubic inches (!) 327 hp @ 7500 RPM / 117.3% VE, 269 lb-ft @ 5500 RPM / 124.3% VE Second combination is a super low buck effort, where the only mods are a decent muffler, Super Six, and a Clifford 276 degree / 0.464" lift cam. And, of course, getting the jetting and spark advance exactly right. Results: 170: 170 hp @ 6000 RPM / 81.1% VE, 166 hp @ 4500 RPM / 79.7% VE 198: 170 hp @ 5500 RPM / 78.2% VE, 183 lb-ft @ 4000 RPM / 76.1% VE 225: 164 hp @ 5500 RPM / 74.8% VE, 199 lb-ft 2 3500 RPM / 72.4% VE Optimized: 3.41" stroke / 186 cid, 171 hp @ 5500 RPM / 80.4% VE, 175 lb-ft @ 4000 RPM / 76.5% VE Last one's a naturally aspirated all out race motor. Cylinder head: Pocket ported with 1.74" intake and 1.44" exhaust valves. Compression ratio: 10.0:1. Induction: 500 CFM four barrel Holley on a Hyper Pak or other four barrel manifold. Exhaust: Dual headers with no mufflers. Camshaft: Clifford dual pattern, 290 degree / 0.530" intake, 300 degree / 0.515" exhaust. Results: 170: 303 hp @ 7500 RPM / 101.3% VE, 229 lb-ft @ 6000 RPM / 101.1% VE 198: 306 hp @ 7500 RPM / 96.0% VE, 250 lb-ft @ 5500 RPM / 97.0% VE 225: 300 hp @ 7000 RPM / 93.3% VE, 267 lb-ft @ 5000 RPM / 92.9% VE Optimized: 3.45" stroke, 188 cid 307 hp @ 7500 RPM / 98.0% VE, 242 lb-ft @ 6000 RPM / 99.7% VE Kinda surprising results, they usually seem to suggest that the 170 or 198 would be a better choice. The first one where the computer suggested building a 2.3 liter slant six may be suffering from a mismatched turbo, since the original idea was for maximum torque and I had it optimized for power.

Author:	Doc. [ Thu Aug 08, 2002 3:50 pm ]
Post subject:	Re: Further details and specs of virtual engines
Looks to me the the model favors a "square" bore stroke combo. (where the bore size is the same as the stroke) This info needs a bit more study & thought. DD Quote: : : That's correct, it has no idea what the : mechanical limits of the engine are. It has : no way of knowing whether the engine would : go into valve float, or if a heavier : reciprocating assembly might sap power. It's : an "airflow-only" model, assuming : optimal fuel distribution and spark timing. : Also, I didn't use any hard data about slant : six heads or manifolds - Desktop Dyno : estimates the head flow data from valve size : and head type. The program probably : shouldn't claim VE numbers with four : significant figures, but I'll show them : anyway. : : Here are the combinations I've tried. I'll give : the peak hp and torque numbers for 170, 198, : and 225 inch combinations along with the RPM : where they happen and the VE at that RPM. : Since Desktop Dyno can also predict the : optimum stroke length for a given : combination, I'll see what that combination : would be if I could get a stroker crank for : the motor, too. Each engine will have : everything held the same except stroke. If : you need more info, I can get all sorts of : things from the program - complete hp and : torque curves, volumetric efficiency plots, : cylinder pressure graphs, you name it. : : First one's a turbo combination similar to what : I plan to eventually run in my '66 Dart with : the original 225. I don't have the ported : head or cam, and I'd want to rebuild it with : forged pistons, but the turbo setup's : getting installed on it at the moment. : : Cylinder heads: Pocket ported with 1.70" : intake and 1.44" exhaust valves. : Compression: 8.4:1 : Intake: Four barrel Holley, Rajay 300B turbo (I : couldn't find a compressor map for the turbo : I have, but this one seems to be sized for : similar engines), 30% efficient air to air : intercooler. The total flow ( not carb size : in this case, but flow through the turbine : inlet) is 600 CFM. : Exhaust: Very free flowing muffler such as a : DynoMax Ultraflow, or open exhaust. : Cam: Mopar Performance "17 second" : cam - 0.436" lift, 244 degree duration. : : Results: 170: 320 hp @ 6000 RPM / 117% VE, 320 : lb-ft @ 5000 RPM / 123.6% VE. : 198: 317 hp @ 5500 RPM / 112.3% VE, 358 lb-ft @ : 4000 RPM / 117.6% VE : 225: 314 hp @ 5000 RPM / 109.7% VE, 400 lb-ft @ : 3500 RPM / 114.9% VE. : : Optimum stroke: 2.56", 140 cubic inches : (!) : 327 hp @ 7500 RPM / 117.3% VE, 269 lb-ft @ 5500 : RPM / 124.3% VE : : Second combination is a super low buck effort, : where the only mods are a decent muffler, : Super Six, and a Clifford 276 degree / : 0.464" lift cam. And, of course, : getting the jetting and spark advance : exactly right. : : Results: 170: 170 hp @ 6000 RPM / 81.1% VE, 166 : hp @ 4500 RPM / 79.7% VE : 198: 170 hp @ 5500 RPM / 78.2% VE, 183 lb-ft @ : 4000 RPM / 76.1% VE : 225: 164 hp @ 5500 RPM / 74.8% VE, 199 lb-ft 2 : 3500 RPM / 72.4% VE : : Optimized: 3.41" stroke / 186 cid, 171 hp : @ 5500 RPM / 80.4% VE, 175 lb-ft @ 4000 RPM : / 76.5% VE : : Last one's a naturally aspirated all out race : motor. : : Cylinder head: Pocket ported with 1.74" : intake and 1.44" exhaust valves. : Compression ratio: 10.0:1. : Induction: 500 CFM four barrel Holley on a : Hyper Pak or other four barrel manifold. : Exhaust: Dual headers with no mufflers. : Camshaft: Clifford dual pattern, 290 degree / : 0.530" intake, 300 degree / 0.515" : exhaust. : : Results: 170: 303 hp @ 7500 RPM / 101.3% VE, : 229 lb-ft @ 6000 RPM / 101.1% VE : 198: 306 hp @ 7500 RPM / 96.0% VE, 250 lb-ft @ : 5500 RPM / 97.0% VE : 225: 300 hp @ 7000 RPM / 93.3% VE, 267 lb-ft @ : 5000 RPM / 92.9% VE : : Optimized: 3.45" stroke, 188 cid : 307 hp @ 7500 RPM / 98.0% VE, 242 lb-ft @ 6000 : RPM / 99.7% VE : : Kinda surprising results, they usually seem to : suggest that the 170 or 198 would be a : better choice. The first one where the : computer suggested building a 2.3 liter : slant six may be suffering from a mismatched : turbo, since the original idea was for : maximum torque and I had it optimized for : power.

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I play with Desktop Dyno too much... https://slantsix.org/forum/viewtopic.php?t=4019	Page 1 of 1

Author:	GTS225 [ Fri Aug 09, 2002 9:35 pm ]
Post subject:	Re: Further details and specs of virtual engines
Quote: : This info needs a bit more study & thought. : DD ************************************************** Hmmmm. I noticed that all the posted results show that the 225 has a considerable jump in torque at considerably lower RPM's. I suggest this is what larger cubes are doing for the virtual engine, and is showing you what your suggested shift RPM might be on the 1320. (After all, torque is what moves the vehicle) Roger GTS225@aol.com

Author:	ricahrd [ Fri Aug 09, 2002 10:16 pm ]
Post subject:	Re: Further details and specs of virtual engines
Quote: : Looks to me the the model favors a : "square" bore stroke combo. (where : the bore size is the same as the stroke) : This info needs a bit more study & thought. : DD so all this means is iff you cram a 170 (2.3) WITH A TURBO you get big power. ell, thats kind of a no-brainer coz it's a rever anyway, and it has 4 more valves than an svo. but can it gdrag a clark cortez around the country? doubtful. remember with all math modeling, it IMITATES life, and tries to predidct it, but all models have this flaw: gigo (garbidge in, garbage out) and over simplification. I have played with desctop dyno. It's neet. But it's not as fun as bench top dyno and dyno dyno

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