I'm planning on upgrading my engine (check sig) this winter. I plan on buying motorville 64cc heads, flattop pistons, roller lifters, and a comp cams XR270R cam. I'm thinking around 10.5 to 1 compression. Otherwise, I will be keeping everything else the same.. This is what I get with desktop dyno 2000:

Head specs (from motorville)

Cam Specs (from comp cams)

Other specs (loosely)

Power


Look good to you guys?

 

Damn dude, thats alot of low end torque!

 

looks nice,.........but I sure wouldn't bet the bank on the Desktop's results.I've always heard that they are close,but I've never seen a head to head,simulated dyno vs. actual engine dyno,but I do know that desktop leaves out some really important factors.
One is rod length,which does indeed have a pretty significant affect on HP,and,as I'm sure you've noticed,the intake section is very vauge.Dual plane or single plane,performer or super victor?Nobody knows,but these days,a Performer RPM can come real close to the numbers a Vic jr. makes,but there are lots of dual plane designs,and lots of single plane designs.so are you running a dual plane cast iron intake,or an RPM?An old Torker intake,or Super Victor?
See what I mean?I have the program installed on my PC,and it's fun to play with,but it really is just a toy.More of a reference point than anything.

Not to say you don't have a good combo,looks like an awesome setup.I'm gonna fire up the hot-air dyno,and guess it at around 460hp at the flywheel.I don't think it's gonna make near that kind of tourque down low,but should still have a ton of low end.The extreme energy cams,whether flat tappet or roller,are in my opinion,the best hydraulic cams that money can buy.

 

You really might want to check your flow numbers. I doubt that they were measured at 1".

 

oh yah, dont worry, im not expecting to have this dead on.. im hoping for a 5-10% in either direction, but im still not gonna cry otherwise. DD is just a good reference point. I actually may have the engine dynoed at the crank, and I could post a comparison. I plan on using my motorville intake.. same design as a performer rpm.

You are right, wasnt tested at 1.. was tested at 28 and didnt make a difference in DD... . The heads are aluminum and only cost $250 a piece (bare).

I am planning on keeping my 1.5 ni-chem coated rockers, but i may go ahead and get roller rockers... It depends, if I keep my block, then the roller lifters are gonne be EXPENSIVE, but if i go ahead and get a 87+ block, and use my low end (with 2pc to 1pc rear man seal adapter), and just use the rollers that are with the block(or get new ones.. which are really cheap anyway), then i can afford the roller rockers... This whole project should jump me from 320hp to about 450-490hp and only cost me $1500 or less.

Im pretty excited about it.. of course, i need to get the body done before more engine work...

 

CORRECTION

The heads are Renegade Racing Components heads, not motorville

 

Maybe because they weren't tested with 0.75 and 0.5" valves either.

 

yah, i checked those too.. didnt make any difference in the whole spectrum.. but I did set it the correct size (2.02 and 1.6) then the power ratings stayed the same

The test numbers are more for reference, im guessing. As you can see, it has a place for me to input the valve size being used separately. And the flow would just be optimum, i would think.

 

Are you sure those curves don't look more like this?

 

yah, positive, im guessing you did something different than me?

 

aaaah, weird

when i was making the changes to the heads, i saved them to the file but not to my engine combo, so each time i brought it up it wasnt there anymore. I changed it again, saved it to the engine combo, and then opened the engine combo again.. same curves you just posted

so, in conclusion: i need to do more playing with different combos or build a new engine, cause less than 100hp isnt worth the $1500 for me.. i could build a 383LT1 with 450-500hp for around $3000

Thanx for catching that for me Apeiron.. saved me some time and a headache!

 

I haven't actually encountered that bug before, but I knew something had to be up with the flow data.

DD needs the valve size and pressure drop the measured flow numbers were obtained with so that it can estimate the actual flow numbers using the valve sizes and manifold pressure during the simulation.

 

yah, if its too good to be true, it prolly is

Well, i guess my plans are shot.. lol, better than going to do it and it not working out as well