Ok, I kinda need some help from someone who has a desktop dyno that would be willing to maybe see what my motor should be putting down... I'm just about to pull the motor and add new heads, carb, and intake and I'm curious as to what I can expect hopefully...Here is a list of what I have for a shortblock...

-1972 LT1 350, punched .030 over, clearanced, and 0 decked.
-Eagle 4340 Steel 3.75" crank
-Eagle 5140 Steel "SIR" lightweight I-beam Rods w/ARP bolts
-KB Flat top -7cc dished hypereutectic pistons and pistons pins
-Clevite 77 rod and main bearings
-Premium plasma moly cast iron rings
-400 balancer and flexplate
-Crane Powermax 234*/244* .488/.510 lift Hydraulic Cam Kit
-New pushrods and timing kit(chain and gears)
-All completely balanced

Now I was looking at this "Head Combo"
Dart Pro 1 Aluminum Heads
64cc chambers(10.9:1 with my shortblock), 2.05/1.6, 215cc intake runner...
Possibley an RPM Air Gap Intake
As for the Carb, I'd like some advice on what you think would be best for my setup... I'm assuming probley something like a Holley 750 Double Pumper but I don't know, thats one place where I'm looking for advice...

Please feel free to make any comments or give any advice, thanks!

Dustin

 

Do you have a PN or grind number to the camshaft?

I wasn't able to find that grind, but I found an Edelbrock Performer with the same duration and lifts.


Installed: dual plane STD flow intake, straight up cam, std rocker ratios Edelbrock provides, small tube headers with mufflers...

RPM HP TQ
2000 156 409
2500 196 412
3000 239 418
3500 295 442
4000 339 445
4500 379 443
5000 404 424
5500 408 389
6000 394 345
6500 364 294
7000 325 244


Going to large tubes with mufflers only shows +7 hp and +4 tq on the peak.

 

Thanks alot. Now does anybody care to chime in as to where my weakspots are? What could I do to get a decent improvement up from that. I really expected it to be more than that but I guess not... Is that cam gonna be big enough? What will be the best carb to run on this application? Now the heads I'm looking at come with either 1.427 double springs or 1.550 double springs. What would be the difference there performance wise? I'm just looking for imput, my goals with this motor were to try to get as close to 500 hp as possible.

 

I still don't think DD is all that good at stuff compared to the higher dollar ones. I've been thinking about purchasing the virtual engine dyno pro simulator ($90) it lets you enter in exact part numbers so it supposely calculates rotating mass and other things DD leaves up in the air.

As for springs I have no clue I kind of doubt it will have any performance differences as long as you get ones that support the lift you're shooting for.

It's really hard to make big numbers on DD2003 without a poweradder at least on a 383. I ran my new setup through to help myself pick out cams and etc, which all just confirmed what compcams line told me. Anyways I only ended up with around 550 hp and 450 tq and that was using a solid roller with 210 CC AFR heads.

 

Check out my post in your other thread.

I think Fireturd's simulation is probably pretty close.
Maybe a bit conservative since DD2000 doesn't model the Performer RPM (dual plane) intake very well using the standard dual plane intake option.

 

Well heres what i came up with, ill need a grind number to get your exact cam so i just used a comp XE268H and 1.5 rockers, holley 750cfm DP, HEI ignition, 1 5/8 headers.


498HP, 516ft/lb

 

So which is more accurate, DD2000 or DigitalDyno? I come up with a 57hp difference on my engine. One thing i notice is that Dig.Dyno is calculating my compression wrong. It says 10.66:1 when the math adds up to 10.04:1

 

I'd assume Digital Dyno Pro (aka Virtual Engine Dyno Pro) is the better of the two considering it accepts part numbers out of a database.

Either way you're just playing a guessing game. Being a Software Programmer myself there is always the fact you can not cover every single use case no matter how hard you try. That's where the errors come in. Computers are only as smart as the programmer that wrote the software. At least till you get up into the Nero Network stuff where pcs can learn by a user entering data. But still the human factor will be the downfall.

 

Digital dyno pro is a more accurate guess

It supposidly takes into account the rotating masses of the individual parts that you select so in my opinion is alot more accurate than dd2000 which leaves alot of things up in the air.

 

So you think that the 498 hp would be more accurate than the previous 408? Thats a pretty decent number, as high as I was hoping, but higher than I expected! I hope that it is decently accurate to what I can expect. What do you think would be a better cam to match with the heads and the rest of the motor? And just out of curiousity I was looking at the heads I was going to buy and for another $1000 I can buy them already cnc-machined and ported. How much of an improvement do you suppose that would provide? Enough to be worth the extra grand or not? As for the cam, I have no idea of the grind number, it was installed last fall and I have since then long lost the box. Those were the numbers to stick in my head so maybe they are inccorrect, I dunno. I'm pretty sure it was a crane cam though so maybe I'm slightly off and you could just use a cam made by crane with specs close to that? In any event, if its decided by fellow board members that a bigger cam would be more applicable to the rest of my motor then that's what I'll do. Cams are dirt cheap when I consider spending $3000 on a set of heads . Thanks for everything so far though!
Dustin

 

I do not think 498 is more accurate. 408 is going to a lot closer to reality than 498 is.

 

OK, so I played with Digital Dyno and wasn't really happy with it. Entering bore/stroke specs and rod length and the program didn't automatically calculate displacement or rod ratio. It didn't even calculate the compression ratio for me. At least what it gave me wasn't what the true compression ratio is for my engine. Same problem with cam specs. Enter in some basic specs and it doesn't calculate others which it could do. I doesn't allow for alternate fuel so my alcohol engine isn't making as much power as it should.

There was a couple of other specs I could have entered but had no options to enter them.

 

It calculates CR correctly for me...

In some ways the old dd2000 is better (fuel choices) and in some ways dd2005 is better (takes into effect rotating mass and the performance of each individual part not just generic tables)

Take the numbers of both dd2000 and dd2005 add them together and divide by 2 and your still no closer to what the actual power of the engine is if you just guessed it out of the blue!