Desktop Dyno 2000.. How Accurate? Realistic #s?

I dont know if this topic it belongs here I just guessed, lol. I just picked up a copy of this and Ive been playin with it here for a good 4 Hours or so and its pretty cool. Just How accurate is this program, Ive been told its pretty close to the real thing but I think im getting some pretty high numbers for example on the motor im gonna be building this winter


383 LT4 4.030, 3.75 stroke
AFR 210 Flow sheets #s
valves 2.02/1.60s
12.50/1 compression
600cfm Intake flow-(i think thats what the Lt1 intake flows)
Long Tubes- open exhaust
Comp Cams solid Roller
110 LSA - 248/255 @ 0.614/0.621 0.050 lift
All on pump Gas


Peak HP = 614 Fwhp @ 7000rpm
Peak TQ - 546 Fwtq @ 5000rpm

These sound a little high the projected Dyno chart looks good though with nice numbers under the curve.


-john

The cam function kinda sucks on it. It simply guesses the lobe profiles. You can have two cams with the same advertised durations and be totally different. By changing the lifter type, you change the programs thinking for cam lobe steepness and radicalness. With it set at hydrolic flat tappet it pretty much nailed my stock heads and cam (came up with 410flywheel, dyned 357 at ground) and had the right curves and peaks.

Problem is, i had no idea what lifter type to use, until i had already dynoed the combo. With hydrolic roller selected, it wasnt even close.

They have a new program out which is TONS better from what i have seen of the previews and trials of it. Still havent gotten my hands on a full copy.

ummm.. are you planning on driving this car on the streets with that cam? Its gonna be a PITA with the solid roller, but you will get more power out of it... Also the LT1 intake flows a bit better than 600 cfm... esp with that kind of a motor, you should be looking to flow at least 1000cfm.

To answer your questions, DD2k seems to be somewhat accurate.. If you put it together correctly.. Looks like you have the flow numbers covered and the cam...

The power does look a bit high, if you want to send me a copy of the file I will look it over for you.. You can e-mail it to me at mleaf@speakeasy.net

Also.. why are you looking to run such a high c/r? Its gonna be tough to drive the car on pump gas without knocking and pinging all over the place.. Im going to be building a 355 with 12:1 cr and Im still worried about it. Although you do have a big cam with a lot of overlap so your dynamic CR should be waay down from your static.

Good luck with it!

Im still playing with the settings but im reworked the cam selection to a get the TQ and power down in the RPMS cuz i really dont want to be spinning the motor that high, its really gonna only be a weekend warrior so the SR factor doesnt bother me that much. The new #s for the cam were

110 LSA SR
235/245 @ 0.600/0.600 @ 0.050 lift
Peak HP 596@ 6500
Peak TQ 556 @ 5000

There still a little high but there a step in the right direction that I want.

Ill try and send you the file.


thanks,
-john

Email sent


-john

Sounds good.. I will try to take a look at it in the morning and post a reply.. Im on my laptop right now and I dont have DD2k installed on it yet..

Happy Turkey Day!

I'd be surprised to see that 235 cam peak at 6500 in a 383. That cam is close to the GM847 and mine peaks at 5800 in a stock motor. I know the lobe separation will move it some, but 700 rpms in a bigger motor sounds a bit much. I think the main problem I've found with DD2K is that its very easy to duplicate numbers accurately in hindsight, but not before hand. FWIW, I just tend to move all the numbers down about 800 - 1000 rpm, and the power levels and curves have matched all the motors that I've made in it and dyno'd.

Brain has hit upon one of the problems I have found with it. I have all the updates to the program but they do not cover port cross section. This has drove me crazy tring to find the missing link.

This is the reason he make peak power so low with the 847 cam. My motor on the other hand with ported heads peaked at 6,900. Then again it never peaked with the stock heads all the way to the rev limiter.

The program does not let you input for the cross section and must use a fixed number. I found by using a big block to start with and input all my small block numbers I can get the results I am looking for with a set of heads that have the correct cross number and My flow numbers ;)

It is no more then a tool. not the sharpest tool but a tool just the same.

I don't know how you all got so lucky with accurate results.

My entries were accurate right down to selecting the flow files
for my heads, valve timing from the cam card, etc.

The program was off b more than 100 HP, wrong peak RPM, the curves
looked nothing like my Dynojet run (even when you consider loss through
the driveline).

For the size and cost of the program, I can't see how reliable it would be.

Get the Engine Anilizer Pro from Performance Trend it is much more accurate.
235* cam is NO problem on the street,262/268*@50 108 mechanical rollers are driven on the street down here with no problem.

I'd be surprised to see that 235 cam peak at 6500 in a 383. That cam is close to the GM847 and mine peaks at 5800 in a stock motor. I know the lobe separation will move it some, but 700 rpms in a bigger motor sounds a bit much. I think the main problem I've found with DD2K is that its very easy to duplicate numbers accurately in hindsight, but not before hand. FWIW, I just tend to move all the numbers down about 800 - 1000 rpm, and the power levels and curves have matched all the motors that I've made in it and dyno'd.


If thats the case ill probably look to move back up to the bigger cam, I used the AFR 210s flow chart but I will be going with a Set of TFS LT4 heads and a complete custom P&P job, I figured the results should be pretty close to the AFRs if not better. I guess if im gonna spend the extra to do a solid roller I might as go a little more radical than an off the the shelf HR such as the 847. I think that with a good tune it should be pretty tolerable on the street even with a cam like the 248/255 as long as I dont make any significant trips with and if I do It will be to the Track and then ill prolly trailer it. I just want to have a car that I can drive not everyday but a fair amount but be considered a little much for doing so.
If I step the compression up that high 12.50:1 I will more than likely have to run a either race gas a mixture right?

But lets say I go with a lower compression say 11.5:1 or less and and am able to run pump gas and increase the streetability of the car?

thanks for all of the impute,
-john

I am running 13/1 on pump gas.Like I have been trying to tell you,the static comp don't mean s***. You need to figure your dcr at 8.9-9.0 and you will be OK on pump gas and the 248/255 is still small.You can take trips in it just like always,just don't load up and go to LA. A 250I/260E@50 is plenty good.

A250/260 on a 108 + 4*advance will make in the neighborhood of 650FWHP@6500 and 580FWT@5000,on pump gas with 12.5 to 1 comp and still be plenty drivable. Like I said don't load up and go to LA. Your gear will let you know about trips not the cam. You can run a 4.10 and be in the middle 3's in overdrive.

Ooops I guess I missed that in your other post about the dcr its been along day. lol. I dont plan on going to LA anytime soon he he but I agree about he gear. The car will be a M6 when its done and you were refering to mid 3s in an auto with 410s correct.
-john

I am running 13/1 on pump gas.Like I have been trying to tell you,the static comp don't mean s***. You need to figure your dcr at 8.9-9.0 and you will be OK on pump gas and the 248/255 is still small.You can take trips in it just like always,just don't load up and go to LA. A 250I/260E@50 is plenty good.

9.0:1 DCR Is still pretty tough on a motor unless it's perfectly done.

In those Evans NPG threads Mr Horsepower wrote about a 10.6:1 DCR 93 Octane pump gas motor! Wow!

You could run some high Dynamic and Static compression on a pump gas motor but most likely it's going to take away from the drivability because you will have so much cam in there.

Remember that HP peak is not only dependant on cam duration, cross sectional area, runner length, header dimensions and cubes all have a big effect on it.

John, the only thing to look out for on a SR motor is the lifters and springs and how they are going to work together. Racerdude is lucky to try out the Schubeck lifters on his motor but most guys look at a $1000 set of lifters and tell you that you are nuts! Once you bust a roller bearing on a lifter you will be one pissed of mofo.

Bret

can somebody please send me the stats of some heads, cams, etc for the LT1? all i have is the basic head profiles and hardly any cam profiles. thanx a lot, i'd appreciate it

9.0:1 DCR Is still pretty tough on a motor unless it's perfectly done.

In those Evans NPG threads Mr Horsepower wrote about a 10.6:1 DCR 93 Octane pump gas motor! Wow!

You could run some high Dynamic and Static compression on a pump gas motor but most likely it's going to take away from the drivability because you will have so much cam in there.

Remember that HP peak is not only dependant on cam duration, cross sectional area, runner length, header dimensions and cubes all have a big effect on it.

John, the only thing to look out for on a SR motor is the lifters and springs and how they are going to work together. Racerdude is lucky to try out the Schubeck lifters on his motor but most guys look at a $1000 set of lifters and tell you that you are nuts! Once you bust a roller bearing on a lifter you will be one pissed of mofo.

Bret



Great info Bret, Im gonna give you a call here in the very near future so we can talk some specs and what not. Can I Get a high quality SR setup with compatible springs and lifters for a reasonable price, or is it really you get what you pay for sort of deal. Do you think that Id be better off with just an Aggressive HR set up. I was thinking that a 500 rwhp motor if not more is very feasable with a SR but I can It still be done with a HR. As far as reliability Im still in between with my understanding. I figure on running a fair amount of N20 (150-200) at the track. Im really liking the kind of number and curves that the SR is making but If were going to be getting into a higher money setup then ill opt for HR. I still want a car that will be somewhat reliable and not just a pain in the azz to drive all the time. Ill talk to you more about it here in the upcoming weeks.


Thanks Bret,
-john

Desktop Dyno falls under the heading of: “you get what you pay for.” For $14.95 just how many pro stock secrets do you think they include?

The Performance Trends software ($240.00 basic - $600.00 for the professional version) is worlds better, but again it’s only as good as the information the programmer puts into it. I've found even the Performance Trends software to be basic engine engineering generic in nature and a good ballpark indicator, but not something you base your mods on.

Why do you think the Pro Stock guys grind a bunch of cams and dyno test them if all they had to do was use Desktop Dyno?

Have fun killing a holiday afternoon while everyone is taking naps, but just don’t use the virtual results to build your non-virtual engine.

You can run 9.0 dcr on the street easy.I even think you could run 9.5.If I was going for lifters I would get the Crower Hippo pressure fed rollers if you can't afford the Schubeck's and watch the ramp speed on the lobes so the lobe doesn't "slap" the roller when it starts to lift. The 262/268 with a converter and a 4.10 gear idles at 1100 and you don't even notice it with the converter.It pulls off from a stop just like a normal car and cruises fine @70 in OD and runs a 10.90-11.00 on motor in a 3600# car and driver.

I had a SR 254/262 cam with .668/.684 lift on a 112 and hated it. Didn't make any more power than other smaller cams I have had and surged like the dickens on the street. This was with a set of 227 heads.

At the time I didn't know how to tune for drivability and that may have made a difference but I found my limit on what I consider "streetable."

The cam prior was a 247/254 with .656/651 lift and it drove fine.

You can run 9.0 dcr on the street easy.I even think you could run 9.5.If I was going for lifters I would get the Crower Hippo pressure fed rollers if you can't afford the Schubeck's and watch the ramp speed on the lobes so the lobe doesn't "slap" the roller when it starts to lift. The 262/268 with a converter and a 4.10 gear idles at 1100 and you don't even notice it with the converter.It pulls off from a stop just like a normal car and cruises fine @70 in OD and runs a 10.90-11.00 on motor in a 3600# car and driver.

The problem with the 9.0 DCR is that it has to live in all conditions that are far from perfect. I wouldn't say it was easy to do.

Ya are right it ain't easy,but with a lot of planning on your combo and cooling it is VERY doable :)

Is cranking psi the easiest way to figure DCR or is it some voodoo formula involving static compression, lobe separation and duration? If cranking psi tells the story, what would be the PSI range your looking for to make this 9 to 1 ratio your alluding too?

I ran a static compression as high as 13.3 to 1 on the street using a 240/250 cam on a 114 and 93 octane gas with no problems at all. It had a cranking pressure of around 230-240 if I remember correctly.

The owner of a local speed shop hit the roof when he saw the cranking numbers. We put a thicker gasket on bringing down the static compression ratio to 12.7 to 1 and everything seemed to be about the same afterwards. Even the dyno numbers didn't change any. No big whoop one way or the other.

Looking at bumping my current combo to 12.4 to 1 over the winter and don't anticipate any problems based upon prior experience but I am very curious as to what the static compression would be.

Bumping up the compression via a thinner gasket would also give me a quench of .039 which I consider about ideal so that may help also.

Is cranking psi the easiest way to figure DCR or is it some voodoo formula involving static compression, lobe separation and duration? If cranking psi tells the story, what would be the PSI range your looking for to make this 9 to 1 ratio your alluding too?

I ran a static compression as high as 13.3 to 1 on the street using a 240/250 cam on a 114 and 93 octane gas with no problems at all. It had a cranking pressure of around 230-240 if I remember correctly.

The owner of a local speed shop hit the roof when he saw the cranking numbers. We put a thicker gasket on bringing down the static compression ratio to 12.7 to 1 and everything seemed to be about the same afterwards. Even the dyno numbers didn't change any. No big whoop one way or the other.

Looking at bumping my current combo to 12.4 to 1 over the winter and don't anticipate any problems based upon prior experience but I am very curious as to what the static compression would be.

Bumping up the compression via a thinner gasket would also give me a quench of .039 which I consider about ideal so that may help also.


Denny,
Do a search on line for a DCR caluclator and enter in your figures.You need to know intake closing point,how far the piston is in the hole,head CC's,valve relief CC's ect. ect..There is a pretty good one by Patrick Kelley it has a brown background,you will know it when you see it.
It'll get the job done for you.

Thank you!

Interesting

I just plugged the numbers into Kelley’s DCR program and it gave me a dynamic compression of 10.23. My static compression is just a hair over 12 to 1.

According to what everyone is saying, the car shouldn’t run very well at all. I used the cam card numbers for advertised duration at .006 and not the .050 numbers per the web site.

Humm?? .040 383, 6 inch rods, 56 cc chamber, .029 gasket, .024 deck, and an advertised duration of 283/304 on a 114 center and 110 intake center line.

Anybody get something different??

Interesting

I just plugged the numbers into Kelley’s DCR program and it gave me a dynamic compression of 10.23. My static compression is just a hair over 12 to 1.

According to what everyone is saying, the car shouldn’t run very well at all. I used the cam card numbers for advertised duration at .006 and not the .050 numbers per the web site.

Humm?? .040 383, 6 inch rods, 56 cc chamber, .029 gasket, .024 deck, and an advertised duration of 283/304 on a 114 center and 110 intake center line.

Anybody get something different??


Denny,
I get 12.04586 static and 9.069288 dynamic.
Man,you'r ready to fly--- Clear the runway.

I used the brown one too,you must have entered something wrong,play with it and get used to it and start with the intake closing calc first,not where it opens.

Do you guys think I am in trouble with my setup?

3.75" stroke, 6" rod

4.030" bore, 16cc dish pistons. .009" piston to deck clearance
.026" head gasket with 4.100 bore

The heads are Stage II CMS aluminum LT-1 with I think a 56-57 cc chamber.

The cam is a 230/236 with 108deg centerline and 112 deg ls. 2deg advance.
Cam card specs : IVO: 5deg btdc, IVC: 45 deg abdc, EVO: 52 bbdc, and EVC: 4 deg atdc.
I am getting 10.858 SCR with a .035 squish, which seems reasonable, but the DCR is 9.80 :eek:

you turned a static of 10.8 and a dynamic of 8.984....just perfect for pump gas IMHO.

Chris

The motor I'm building has 9.56 static and 8.40 dynamic...but then again I'm boosting it, yeah fun.

How did you get 8.984 DCR? When I use Kelley's program, it gives my 9.89 DCR. Am I doing something wrong?

How did you get 8.984 DCR? When I use Kelley's program, it gives my 9.89 DCR. Am I doing something wrong?

Use the center tab on top first,then the left tab,then the compression tab. Play with it and get used to it,it figures correctly,if used correctly.

How did you get 8.984 DCR? When I use Kelley's program, it gives my 9.89 DCR. Am I doing something wrong?

Use the center tab first,then the left tab,then the compression tab.

I couldn't find Kelly's so I used KB-Slivolite. Theirs works pretty well and it's pretty straight forward.

Chris

The cam is a 230/236 with 108deg centerline and 112 deg ls. 2deg advance.
Cam card specs : IVO: 5deg btdc, IVC: 45 deg abdc, EVO: 52 bbdc, and EVC: 4 deg atdc.


A 108 Centerline on a 112LSA is +4 degs of advance, but your Cam Card specs are right for a 112 LSA 230/236 cam advanced +2.

Just some help there

Bret

Ok I actually got mine set right for the cam we're using and Static is 9.57:1--About where I wanted it. Dynamic is 7.07:1...I'm guessing this should be good for 20PSI and spinnig all the way up to 8K RPM. Atleast that's where the cam will make peak HP.

Chris

Cam specs out at 257/252 @ .050 .683/.683 Lift with 1.6 Rockers on 115 LSA and 111 ICL.

Just a little cam ;)

Good call Bret. Thanks! Looks like it is a 110 deg lobe centerline. DCR is still high (9.8).
Thank you all for the help.

John, the only thing to look out for on a SR motor is the lifters and springs and how they are going to work together. Racerdude is lucky to try out the Schubeck lifters on his motor but most guys look at a $1000 set of lifters and tell you that you are nuts! Once you bust a roller bearing on a lifter you will be one pissed of mofo.

Bret

god damn i just checked out schubecks website! 904CI DOHC 4valve 1200hp NA ON PUMP GAS! 6" STROKE, 9"ROD, 4.90 BORE, Water jacketed exhaust i guess you get what you pay for, at 80G's

Denny,
I get 12.04586 static and 9.069288 dynamic.
Man,you'r ready to fly--- Clear the runway.

I used the brown one too,you must have entered something wrong,play with it and get used to it and start with the intake closing calc first,not where it opens.

The funny thing is this is supposed to be the max compression you can safely run based upon what I'm hearing and the motor likes 100% stock timing plus a degree.

Took the stock program and tuned it for drivability getting the trim and other things all squared away first. On the dyno we used a Tech II to check for knock retard and tuned the AF using the wideband so it was between 12.8 and 13.1. (which the motor liked best using a 160 water temp as the baseline reference)

Being we saw no retard using the stock program, I added another degree to see if it wanted more. The car picked up slightly showing no retard at all. Another degree and it still didn't show any retard, but didn't improve the hp so I backed it down a degree.

Sure wasn't hard to tune is all I'll say if that's the cutting edge.

Sorry I never got back to you about your DD2k file, but I was having a bit of computer problems... I did try to open it once everything was fixed, but it looks like we are running different versions of DD2k, so I cant even open the file to look at it..

Sorry man!

The funny thing is this is supposed to be the max compression you can safely run based upon what I'm hearing and the motor likes 100% stock timing plus a degree.

Took the stock program and tuned it for drivability getting the trim and other things all squared away first. On the dyno we used a Tech II to check for knock retard and tuned the AF using the wideband so it was between 12.8 and 13.1. (which the motor liked best using a 160 water temp as the baseline reference)

Being we saw no retard using the stock program, I added another degree to see if it wanted more. The car picked up slightly showing no retard at all. Another degree and it still didn't show any retard, but didn't improve the hp so I backed it down a degree.

Sure wasn't hard to tune is all I'll say if that's the cutting edge.

Denny,
Thats what I had said in one of my earler posts that-- I believe you can run 9.5 dcr on pump gas on the street ---- and be good to go as long as you have GOOD COOLING.

Denny,
Thats what I had said in one of my earler posts that-- I believe you can run 9.5 dcr on pump gas on the street ---- and be good to go as long as you have GOOD COOLING.


Based upon my current setup and one that I had that honestly was running 13.3 to 1 static, I would be every bit in agreement. This thing literally drives like stock and instead of pulling out timing, you can actually run a couple of degrees more with no issues.

However as per your comment, I do have a high flow HD electric pump, BeCool radiator, water wetter, no coolent, 160 thermo and underbody panel for better cooling.

You guys got it all over me when it comes to the hard core math and engineering aspects, but I' ve got a ton of dyno sheets, cam cards and flow sheets sitting around.

The difference between wisdom and intelligence is experience. Good ol street smarts and experience goes a long ways.

Appreciate everyones insights rounding out and adding to my knowledge base. Thanks Guys!

Well you have all the right stuff for cooling.If you run into issues contact Evens cooling and do their water pump trick and their coolant. you should run some water solubble oil in there to stop corrosion and rust.
Good luck dude.

Well you have all the right stuff for cooling.If you run into issues contact Evens cooling and do their water pump trick and their coolant. you should run some water solubble oil in there to stop corrosion and rust.
Good luck dude.

Sounds like good advice! Again guys........ you really are the best! Thanks!

I prefer DynoSim over DD2000. :D

Although when I was using DD2000, I was able to simulate several of my friends' motors to where they were very close to how they dyno'd.

Do you guys think I am in trouble with my setup?

3.75" stroke, 6" rod

4.030" bore, 16cc dish pistons. .009" piston to deck clearance
.026" head gasket with 4.100 bore

The heads are Stage II CMS aluminum LT-1 with I think a 56-57 cc chamber.

The cam is a 230/236 with 108deg centerline and 112 deg ls. 2deg advance.
Cam card specs : IVO: 5deg btdc, IVC: 45 deg abdc, EVO: 52 bbdc, and EVC: 4 deg atdc.
I am getting 10.858 SCR with a .035 squish, which seems reasonable, but the DCR is 9.80 :eek:


Hmmm Sounds like the motor I just built but I used AFR 195's and 230/244 112LS (CC 306). I put 414RWHP/412RWTQ but I think there is more (6-10HP) with a bit more tuning

So what dynamic compression ratio calculators are you guys using. Ive found two. One wants cam timing abdc +15 degrees (55+15=70) got me at a dynamic compression of 8.73 . The other wanted cam timing only abdc (55) which got me at a dynamic compression of 9.77. Donno which is right, which is wrong.

Also i also would like to know the accuracy of the desktop dyno 2000 program. Threw my set up on there.

412 (400 , 030 over , 3.8" stroke)

AFR 220 Heads (used the race ready flow #s)

Solid Roller Cam
264/272 @.050
649/649 lift
107 LSA
29 btdc 55 abdc
67 bbdc 25 atdc

Super Victor Intake (single plane)

11.41:1 static compression

950cfm carb

Large Tube Headers/Open Exhaust

Threw it all in and it came out to what i expected, but thing is i dont want to get my hopes up. Still sounds like you guys are mixed on the accuracy of this program (atleast the older versions) so would like to know if you guys think its realistic or if somebody has an updated version of this program or a better one if they could throw my set up in there.

609hp @6500rpm
542ft-lbs @ 5000rpm

Thanks fellas appreciate it.