MrPhotographer0

From other boards, ive read desktop dyno is pretty accurate.. Like within 10 horsepower.
But ive also got Drag 2003 and with my desktop dyno figures im putting down like
ET: 11.561
Trap:118.5
0-60: 3.414
0-100: 8.252
Rollout .138
60ft 1.7
330:4.799
1000:9.654
1320:11.561

Vehicle:
84 camaro
Wheelbase: 101"
Weight 3500 lbs
% on driving wheels 42%
Frontal Area 21 sqft
Aero Drag coefficent .33

Engine:350ci
Displacement:355ci
Peak Horsepower 460hp @6500(Based on camquest specs of Motha Thumpr and Desktop Dyno output figures)
Peak Torque 426 ft-lb @ 5000

Transmission: GM Turbo 350
Torque Converter speed: 3500
Torque Converter Multiplier:2.30
Torque Converter Slippage: 6.0%
STD Gear Ratios: (2.52/1.52/1.0)
Rear-Drive Ratio: 3.73

Tires/Wheels: Mild Race
Tire Diameter 26.0
Static Tire Width 10.0
Traction Coef. 2.70
Growth Factor 10.0

Driving style: Custom
Redline RPM 6600rpm
Rollout:6.0"
Launch 3500 rpm
1->2 6300 rpm
2->3 6300 rpm

Weather
Low Temprature Winter
Temp: 50.0 f
Humidity: 10.0%
Elevation: 112(my local elevation)
Barometer: 29.80 inHg

so hmm,
Im wondering if this is possible.. thoughts?

AlkyIROC

Garbage in, Garbage out. The accuracy of DD depends on how accurate the data you put into it is. The biggest piece of data for accuracy is head flow numbers which very few people have.

No matter how much I try to fudge numbers around, I can't get dyno or drag 2000 to give me accurate results based on real track results. The best I can hope for is to play "what if". What if I change this, would it be better or worse. At least that can get you in a ballpark range. Drag 2000 recommends I use 4.56 gears. I tried them for 2 races and switched back to 4.86 gears. The car liked 4.86 much better than 4.56.

So many factors can't be calculated in to DD. Tire pressure, jetting, ignition timing, plug gap or heat range, suspension setup can all factor in how much power the engine makes or how fast it runs down the track. DD and Drag only assumes everything is adjusted perfectly for maximum performance.

MrPhotographer0

well, i'm hoping to somehow be in the 12's.. But, we'll see how it pans out.
Thanks for the help though!

Guest

There are way too many variables for the drag results to be any good. The dyno program if the input data is right works pretty decent for what it is, an educated guess.

I'd be really surprised if you were going to make 460hp.

MrPhotographer0

me tooo. I do want to reach 400, which by Chevy High Performance, its pretty possible with my setup...
But i'll have to see how much the head ports and whatnot work out to determine how much i'll get...

blackbmagic

Id be surprised If you could come close to 400hp at the crank with the 882 heads unmodified. My heads are milled down and with my setup id be lucky if I could make 350hp. Comp cams recommended the thump er cam for me and estimated ~325-350 at the crank. Without major port work or aftermarket heads I don't think you will hit 400hp with 882 heads.

Also the 750dp isn't really needed you can use a 650dp with no problems with that setup.

Depending on who ports your heads, how much and how long it takes. You might be better off with a set of aftermarket heads. I got a set of brodix heads assembled for 1150. Out of the box they are able to make upwards of 500hp with the right cam, and intake.

Orr89RocZ

iTrader: (20)

I have DD'd my motor and compared it to the real world dyno results. Desktop shows crank hp but dyno was chasis numbers at the tires so hard to say what is what.

I can say the power curve for peak hp RPM was pretty close to what DD predicts but the numbers DD gives out I feel were too high. When I chose small tube headers and mufflers, the numbers came down to a more reasonable estimate, even tho I had a 4" exhaust with 1.75" headers. Also limited throttlebody flow. I would have thought my 383 was a 500hp motor as it was about 400 at the tires.

I think I did Drag2003 it as well but dont recall the results. I will have to double check that again if I still have the program.

I ran 11.47 at 118.x with best trap of 119.x on a 1.55 ish 60 foot. I know it weighed 3450 with me in it. I'll play with the numbers to get the results abit more accurate.

MrPhotographer0

oh no no no, i havent updated that yet.
Im not running 882's. I've got Vortec's that are soon to be magic'd up.

and thats good news, i hope that it turns out decently close!

JakeJr

I use Engine Analyzer Pro 3.9 much the same way as AlkyIROC. Changing the variables shows me if I'm moving in the right direction or not.

Right now I'm researching for the best cam recommendation, so I've been going through CompCam's catalog (just the one I'm using for now) and plugging in different profiles (XE, XFI, Magnum, etc.) and let the program crunch the numbers. Based on the numbers I see I can tell which family of profiles his engine specs will like best.

As an example, a new feature allows plugging in cam duration specs (0.000"/0.050" and 0.050"/0.200"), not just advertised and .050" duration numbers. This allows the program to factor in different ramps, how aggressive they.

Of course, EAP is close to $500 so when it comes to simulators I guess you get what you pay for. By that I mean EAP allows for a greater number of inputs. Yet, even then, it's the accuracy of the inputs that can make or break the accuracy of the calculations.

When I comes to head flow, I research as many sites as I can where independent shops have flowed the heads I'm running. For the 41x CID I'm researching for my son's 96 LT1, and since he's running Dart Pro1s, I didn't use ONLY Dart's numbers, but, instead, numbers posted from mags, like GM HIGH TECH PERFORMANCE, POPULAR HOTRODDING, etc.

I've done it by averaging all the numbers I could come up with, but I also ran the individual numbers just so I could compare.

The more expensive programs allow the user to plug in the ignition timing curve, injector size, fuel pressure, the aggressiveness of the cam's ramps, friction losses, atmospheric pressure and temps, head port dimensions, piston coatings, valve spring specs, on and on. So many variables I can't list all of them here.

They're tools; just have to use them wisely.

Jake

Orr89RocZ

iTrader: (20)

Ok i just ran mine again.

Engine file I setup so its 514hp at 6000 rpm but holds 512hp to 6500 rpm which is just like my dyno graph in real life. Torque says 487 but I think thats abit optimistic. When simulating crate motors i've seen dyno'd, torque output in DD2003 is high. My 383 only made 380wtq but between 4000-4500 rpm just like DD2003.

SO the curve looks ok. I modeled it as a single plane intake, 850cfm and small tube headers. I had HSR which is a tunnel ram but that boosts power alot in DD.

Running drag 2003 with 98 camaro as my starting model, i changed wheel base to 101.1 inch, 3450lbs. Mild race tires, th700r4 trans, 3600 stall, 3.42 gear, etc etc. 2000 ft elevation which is about right for my track in the summer, maybe a bit lower. DA might have been closer to 2500 that night. Not sure.

6600 rpm shift point where I normally shifted.


Results show 11.43 at 118.8 mph... 1.65 60 foot. Thats incredibly accurate. I ran 11.47 at 118.x on a 1.5x 60 foot. 1/8 mile of 7.29 at 96...thats about right for ET but abit off in speed. I trapped 92-93.

Not all that bad.

1989GTATransAm

iTrader: (3)

Well I think Desk Top Dyno is out to lunch with my 368SBC motor. I'm running a monoblade with 1300 cfm but I entered 1100 cfm accounting for losses in the 3 1/2" air intake track. I will be using exhaust termination boxes which simulate open exhaust so I used small tube headers open exhaust. I also used single plane high-flow according to the instructions. My TPI intake manifold flows over 300cfm.

DD spits out 598hp@6500rpm with torque 528@5000rpm. With small tube headers and mufflers it spits out 563hp@6500rpm and torque 510@5000rpm. The last may not be to far off but IMHO optimistic. I will be going on the chasis dyno in a few weeks so we shall see using a 20% drivetrain loss and without he exhaust termination boxes. Then the next time on the chasis dyno will include the exhaust termination boxes with the headers designed for them. We will see what difference that makes if any.

Orr89RocZ

iTrader: (20)

Your's would be the best example because you actually engine dyno'd that motor. Made 535 hp right?

MrPhotographer0

89rocz,

thats awesome, im hoping im somewhere in the 11's with my project, maybe i can put her on a diet too and lose some weight..

Orr89RocZ

iTrader: (20)

try changing your drag2003 file's shift points to 6800 if its peaking at 6500 rpm. May pick up time on the simulation but 450 hp could be doable and sneak into the 11's

MrPhotographer0

Damn, i didnt save it, and i hibernated my computer earlier, so it lost it..

But, ive got it in text here! haha! So i'll check that out,


EDIT:
Changed redline to 7000, and shift at 6800 1-2 and 2-3 and its down to 11.402/119.9
Hmm.. Lets play in Desktop Dyno and see if we can get some more crank hp, and see what happens..

MrPhotographer0

whats a stripped interior camaro weigh?
Plus, one power seat, one manual seat, stock dash, aftermarket gauges
no carpet, manual doors and locks

good ballpark?

1989GTATransAm

iTrader: (3)

"Your's would be the best example because you actually engine dyno'd that motor. Made 535 hp right? "

Hi Orr

Yes you are correct but on the engine dyno that was with a Victor Jr intake manifold that did not flow anywhere near as good as my First TPI intake manifold. Also the carb did not flow anywhere near what my monoblade does so we shall see. So maybe 550hp with the good flowing intake parts. That is well below the 598hp predicted by DD. That would be off 8%.

Orr89RocZ

iTrader: (20)

Mine was around 3420 or so with me in it (was 160-165 then), no carpet or interior plastics, 8 pt roll bar, and power everything, 2 corbeau seats on drag wheels/skinnies

80 for the cage atleast, 20 or so for power windows/locks/etc, 25 or so for seat. I'd say around 3300 with 160 lb driver. Some models may be even less

MrPhotographer0

Well i crunched some numbers on the Thumpr cam, and since i cant afford it, i didnt pay it much attention.
But, i did find a nice summit cam,
292/292 .488/.488 putting out 466@6500 and the cam cost 100 bucks!

So, with those punched in, and my plain jane camaro in, at 3300 lbs
Redline moved up to 7000 and shifting at 6800, i'm sitting at 11.023 @ 123.8

Add a 50 shot and im in the 10.642 range.. Wow,
Now that, i could live with

BLUETA

Like "JakeJr", I researched head flow numbers from different magazines to get what I needed. I also ran a stock 305 on DD2000 for comparison till I got the stock hp/torque ratings. Then I had the correct variables. When I ran my 406 on the chassis dyno, I had to account for the higher stahl converter, but the numbers came out really close to DD2000. The hp and torque curves looked good, and the the rpm where the peak hp and torque was also close.

I mainly used the DD2000 to compare heads and cams. Even if it calculated wrong, it was the same every time. So comparing to each other, I could fine tune my cam and head choice to get the power in the rpm range where I wanted it.

JakeJr

Another thing to consider is when comparing the airflow of a carb with a throttle body you're comparing wet flow with dry flow. TPiS' Insider Hints booklet (maybe other places too) has the formula on how to convert one to the other.

One other thing I recently read in a mag article is about carbs; that carbs from two different companies even though they're advertised the same, say 750 CFM, won't flow that number. Often neither will flow 750 CFM; one more and the other less.

So plugging in those advertised numbers will give inaccurate results.

Jake

25thannivZ28

Time to resurrect an old thread....

Is there any newer, updated software that can tell me more than what my Desktop Dyno 2000 offers? I'm having difficulties finding out what my IVO (BTDC) and IVC (ATDC) and of course the EVO & EVC.

My Cylinder head flow#'s are straight from the website, which is a custom saved file within the software. Not shown here

Based on what my specs are that I put in is as follows. I did not verify any of the IVO, IVC, EVO & EVC at all. i'll have to call Howards cams tomorrow.



Engine Specs (Zoomed in)


Dyno Graph

25thannivZ28

Oops, I didn't realize there is a "Tool" on the desktop dyno that does all the math for you. I entered in all the specs, given the duration @ .050 & the lift specs of .603/.619 (with 1.6 rockers) and it appears that I came out at a total of 561hp @ 6500 and 535tq @ 5000.

I wonder how accurate this is, once I take the quarter mile this year and/or do some dyno runs, i'll see if that is about right. (Given the 17% drive-train loss)

kenbob

I use desktop Dyno for all my builds and the last 4 engines were within 2.2 horsepower on the low side the engines actually made more power but you must put in exact measurements temperature and humidity as well also for some you need to account for elevation. Yes this is very hard to do if you ported your own heads and don't have access to a flow bench. But if you are bolting together aftermarket parts such as Edelbrock or trick flow specialties their heads come with a flow chart. Make sure you pick the right intake and exhaust as well if you just purchased it and bolted it on its standard flow if you cleaned it up and smoothed out the runners it's a high flow. If it is port/gasket matched or a sheet metal intake it's a max flow. You get out what you put in. To double check follow a build from engine builder magazine put in all the data they list and see how close you are. Remember to use the ambient temperature outside for best results temp can cause up to 15 horsepower difference