Desktop Dyno?

[maddad]

Hi Ned S. I don't know which heads are best, but here's some info to think about as you decide on intake volume.
Just built a 413 ci SBC(400+.060) to spin an older Volvo drive in a fairly heavy v-bottom. With Dart Iron Eagle 2 180cc heads it made 490lbft @4100 and 432HP @5300, where I ended the dyno pulls. The curves indicate peak HP was still a few hundred rpm away. So with 413 ci, I could have made more power where I wanted it with even smaller, maybe 165cc, heads. Or vortecs.
Cam is comps 4x270h.

[Ryan00TJ]

Punched in all your info on my DD program. Used HP manifolds for exhaust and single plane intake. 750 carb, 9-1, your head flow numbers and camshaft.
2000 155 407
2500 203 426
3000 256 449
3500 300 450
4000 337 443
4500 364 425
5000 371 389
5500 363 346
6000 339 296
Just an idea.. The motor is begging for a larger camshaft. A 224/230 Comp XM276HR bumped the hp up to 425 and produced a much flatter torque curve that held close to peak torque up to 5000rpms.
I would opt for a high velocity 195cc port head for your setup. AFR Eliminators are very sweet, they flow close to the 220 Canfields but with a smaller port with much higher velocity.

[pw_Tony]

R.P.M HP TORQUE
2000---------155------------407
2500---------202------------425
3000---------256------------448
3500---------301------------451
4000---------339------------445
4500---------368------------430
5000---------383------------402
5500---------378------------361
6000---------357------------312
6500---------329------------265
7000---------283------------212
This is according to desktop dyno with the numbers you gave out. Pretty much mostly torque and little horsepower. But then again who knows how close the torque is when desktop Dyno does have input for Port size to help with velocity

[pw_Tony]

Opp I guess I did something wrong

[GofastRacer]

Intake:
Valve Opening= 1.9 BTDC
Lobe Center= 105.4 ATDC
Duration= 210.1 Crank DEG
Max Cam Lift= .31429
Net Valve Lift= .47144
Lobe Area= 23.27
Exhaust:
Valve Opening= 44.8 BBDC
Lobe Center= 115.4 BTDC
Valve Closure= 1.9 ATDC
Duration= 222.9 Crank DEG
Max Cam Lift=.33799
Net Valve Lift= .50699
Lobe Area= 26.45
A couple things missing here, intake closing and what are the timing events at, .050???..

[cfm]

I apologize if it looks like I responded to this thread to tell you that your combo is "off." I was responding to you asking for a desktop dyno report so you can get a better idea of where to prop your boat. I truly feel desktop dyno is not going to accurately give you what you are looking for.
If you are happy with the performance of your engine, leave it alone. If you want to better it, well, that is a different story. I'll help if that's the case. If you want to pursue this 'sidetrack' that I guess I started then please tellu us everything about the boat and what your ultimate goal is and what your preferences are.

[Ned S]

cfm, No need to apologize and actually the results others posted are what I feel in the seat of my pants when I am running it. She pulls hard down low and thru the midrange and runs out of steam at the top. Actually this is my first American iron build. My hobbies in the past were sports cars and shifterkarts so the only engines I have experience with are the Mazda rotary and 125cc Honda 2 stroke. Im getting too old for the shifterkart and tired of the money pissing contest in all forms of motorsports so I decided to get back into boating. The $250-$500 I used to spend on race weekends can buy a lot of gas and beer.
My boat is a 85 21' Scarab 1 When I got it it had a 350 that probably had 300 hp and it would run about 50 with a 19p prop at 5000rpm. I did not have a GPS at that time. It broke down every other time I took it out so I decided to rebuild, repaint and rewire everything. That was with an Alpha drive. We now have a Bravo 1.5 As it is right now with a 21p prop and GPS in hand I got 63.8 at 5400 rpm. That was upstream on a river on a windy day. My goal is 70-75 NA on regular fuel. I ski occasionally but dont mind changing props. Being somewhat reliable is an issue as we can get as far from the dock on the Kaskaskia and then on to the Mississippi rivers as we want as long as fuel is available. No premium fuel is available unless one wants to tote cans. One thing I noticed my last time out is that if I cross another boats wake or hit just a bit of rough water anything that will bounce the bow up she will pick up speed for a bit but the engine cant keep it up for long. To me it seems and the dyno simulator shows that I have no power on top. I would prefer not to change cams this season but heads would be easy.
I did however blow my cam specs because I did not have my specs on.
Intake & Exhaust
Lobe Center Sep= 110.4 Cam Deg
Valve Overlap= -3.8 Crank Deg
Intake
Valve Opening= -1.9 BTDC
Lobe Center= 105.4 ATDC
Valve Closure= 32 ABDC
Duration= 210.1 Crank Deg
Max Cam Lift= .31429 in.
Net Valve lift= .47144 in.
Lobe Area= 23.27 in. deg.
Exhaust
Valve Opening= 44.8 BBDC
Lobe Center= 115.4 BTDC
Valve Closure= -1.9 ATDC
Duration= 22.9 Crank Deg
Max Cam Lift= .33799 in.
Net Valve Lift= .50699 in.
Lobe Area= 26.45 in. deg.
GofastRacer asked for the timing evens at .050 I dont have these specs.
I dont want to be a moocher. What is the best DD program to use?
Thanks, Ned

[Ned S]

Here is a pic of the boat when I was fabricating a windshield.

[jmherbert]

I cant give you dyno #'s, but my non-expert opinion is you need more cam, especially for those heads. Its a 383 running 200cc Dart Iron Eagle platinums, and a crane 284H (228@050) cam. Tyler Crockett (look him up if you don't know who he is) spec'd out this cam and a brodix dual plane intake. This motor pulls hard from idle 'till about 5500, which is my personal RPM limit. Of course, I am also 10.3:1, which has run on 92 octane so far.
I would build this motor again, with the only change being machined pistons to get the compression down to around 9.5:1 for piece of mind.

[GofastRacer]

Intake & Exhaust
Lobe Center Sep= 110.4 Cam Deg
Valve Overlap= -3.8 Crank Deg
Intake
Valve Opening= -1.9 BTDC
Lobe Center= 105.4 ATDC
Valve Closure= 32 ABDC
Duration= 210.1 Crank Deg
Max Cam Lift= .31429 in.
Net Valve lift= .47144 in.
Lobe Area= 23.27 in. deg.
Exhaust
Valve Opening= 44.8 BBDC
Lobe Center= 115.4 BTDC
Valve Closure= -1.9 ATDC
Duration= 22.9 Crank Deg
Max Cam Lift= .33799 in.
Net Valve Lift= .50699 in.
Lobe Area= 26.45 in. deg.
GofastRacer asked for the timing evens at .050 I dont have these specs.
I dont want to be a moocher. What is the best DD program to use?
Thanks, Ned
So what are these timing events taken at??, The best DD right now as far as I know is the 2003 with Pro Tools version, haven't checked lately to see if they'rs a newer version though!... Engine Analizer is even better yet!..