Good morning gentlemen,

I currently have a 440 sitting on the dyno with somewhat disappointing results. I pieced together a combo that I had hoped to make north of 550hp but am falling about 30HP short of that. The first thing that has me somewhat confused is that the motor is only pulling 680 cfm through the carb. I would have expected at least an additional 100 cfm. The torque curve is good and amazlingly flat from 3000 rpm up to 5000-ish making at or above 500lbft through much of the curve. The motor peak hp at 5600 rpm ended up at 519hp and fell fairly quickly after that. By 6000 rpm the motor was done making power. The builder says I need more cam (duration), I think he is wrong and something else is choking the motor. I have posted the 1st dyno run numbers which was a short pull but is consistant with the following pulls up to 6k. 32 degrees of timing on pump 91 octane gas. What do you guys think?

Here are the motor Specs:

Stock stroke 440. Cast crank & LY rods
ICON 968 .030 pistions. Zero Deck height
Compression is just a smidge over 11.1:1 with .039 gasket
Toth Ported ProMaxx heads (300+on flow bench) cfm on intake Finished Chamber is 76cc
PAC Springs and Comp retainers/locks
Hughes engines Solid Cam STL5054BS3-8 BB SLD FLAT TAPPET CAM 250/254 -108ºLSA 3 BOLT .392"/.400" LOBE LIFT: Gross Lift I .627/E .640 with 1.6 Rocker
Hughes Roller Rocker 1.6 ratio
Trick Flow single pane intake, port matched.
MSD Dist/Ignition Set at 32 degrees at full advance.
Melling HV oil pump and Milodon pan.

In my opinion you have the wrong intake on that combination. Switch to a Performer RPM and you should see better results.

Tom

I think your builder is correct. You need more duration......and ignition timing.

What did the heads flow @.600 lift? Did you try more timing? You know what cranking compression is? Seems to me it could use more timing.

Just to throw it out there, I agree would have tried more timing. The BSFC numbers look poor, it is using a lot of fuel to make the power, but the A/F ratio is close. Did you degree the camshaft? First thing I would do is get a cranking compression reading, might tell you if cam is not right.

I'd have to go back and review the numbers but the flow numbers in the low 300's if I recall correctly... I dont know the cranking pressure offhand but the timing was limted to 32 degrees due to detination

The builder did degree the cam, I can confirm that. Not sure what cranking pressure is, I'll refer the builder for the information

The Vac Secondary carb isn't helping. Recent episode of Engine Masters showed a significant increase in peak hp and tq with a double pumper on the dyno vs the same sized vac Secondary carbs. Logic being that as RPM increases the vacuum through the Secondary venturis pull additional fuel through the squirter nozzles of the dp carb. They have video confirming the phenomenon. Something like 15 hp if memory serves me. If you can source an 850 holley dp, give that a shot. More timing like others have suggested could help also. A larger double Pumper carb and timing sweeps are easy to do in comparison to a cam swap.Good luck.

I believe the last dyno pull was with a Holley 950HP carb

Add some race fuel and bump up the timing. Otherwise, I'd be looking at a cam change if you want to stick w/ pump gas.

What carb are you using? Also how accurate is the dyno? I've seen some dynos put out "happy" numbers but when the cars went to the track the ET is not near what it should be. Maybe this dyno is "low"?

For comparison my engine is:

440 stock stroke
10.9:1
TF 240 heads
MP .557 cam
Crane Gold 1.5 rockers
Victor 340 intake
Proform 850 carb
Hooker 2" headers

Everything was out of the box and bolted on, no port work, gasket match, etc. Engine goes 6.70s in the 1/8th in a 3150lb car. According to Wallace Racing Calculator it's making 504 Flywheel HP.

Cranking pressue was-190psi...

251 intake duration 256 exhaust 108 lobe separation: 78 degrees of split overlap per the builder

So if I were to look at a cam swap, what would be the reconmendation?

jwb123 is correct, the VE numbers are off, looks like about 8%. That being said, it's using a good about of air and using a LOT of fuel to make power. The A/F numbers are not that accurate because of the way they are calculated, i would prefer O2 sensors. So my question, did you pull any jet out of it, and how did it respond?


Joe

Like Chip said.....Put some good fuel in it and bump the timing to about 36 and your power will appear like magic. 11 to 1 compression on pump 91 fuel is going to get you in trouble most of the time with a wedge engine. If you cannot run more than 32 degrees without detonation you have to much compression for the fuel you are using.
Todd

I stand corrected: Builder says it made no difference in HP or Torque by moving timing up to 36 then back to 32. Lost power under 32 degrees

Do you have a reconmendation on which direction to go with the cam?

Fast68plymouth here on the board is the cam guru. Porter Racing Heads 802-951-1955

I think the cam is too big for the rest of the build. The old MP solid lifter would make more than 550 hp in an 11:1 440 with ported heads. I don't have any experience with those heads but my guess is that they aren't a good match for that cam on that engine. It is a curious result, I'm not 100% sure why it isn't making more power but my guess is that the big cam is killing power down low and the heads are killing it up top.

Running a cranking compression test while it is on the dyno and see what it says. Look at the plugs to see what they say. If the engine is in good mechanical shape then I'd suspect a mismatch of parts. I'd go about 10 degrees smaller on the cam if the heads you have won't flow up top. Then it will at least be a fun street engine. If you want a race engine then you'll most likely need to have the heads looked at by a pro.

Unfortunately, without some history from that dyno, or results from other similar builds....... you’re just “racing dynos”.

The FW headers aren’t helping with the top end power.

Cam is not too big(motor makes decent TQ).

VE numbers are in la-la land(imo, they’re just plain wrong).

Bsfc numbers are poor.

But, that’s two examples of why you’d need to have history with that dyno to really assess the results.

The fenderwell headers are most likely killing power. I've seen them lose 50 hp on a race engine. My guess is still that the heads are the problem but it could be something else. Double check everything to see if you have any "dumb" mistakes and then go from there. If you want to make more power you'll most likely need to pull things apart and take stock of what you have. Otherwise just run it as is.