74vetteman

I finally had my 406 dyno'd today on an inertia dyno. The results are pretty much what I expected and this combo should work pretty well on the street.

We made a total of 19 pulls, tried 3 different carbs (750 demon dbl pump, 750 Holley dbl pump, and 950 dbl pump for kicks), and used an 02 sensor in the number 7 header primary. The dyno used is known to be stingy compared to others in the area, but is repeatable within 1-2 hp. It also has a lot of capacity. The engine before me (blown alchohol small block) made over 2100 hp!

The engine:

2 bolt main 400 block (high nickel) was put in oven and all crud was burned off, then shot peened (also stress relieves the block. Filled with block filler to the bottom of the front frost plug holes, then bolted on a head till the filler hardened. Large holes in deck fitted with pipe plugs. Oil passage ways contoured for better flow and lifter valley polished for better oil return. All casting flash removed. Block was align honed (with studs installed in mains) then bored and honed .030 over. Pistons were installed ~.005 in the hole (decked about .020).

Parts used:

All ARP fasteners, Scat 3.75 cast steel crank internal balance for 6 inch rods (still needed mallory), Eagle 6 inch h beam rods, SRP forged pistons, Crane roller cam 222in 230ex at .050, 1.6 roller rockers, AFR 210 heads (race ready porting), Weiand Team G 7530 single plane intake, Demon 750 double pumper carb, Hooker super comp 1 3/4 headers.

Results:

Torque: 493.7 at 4533
HP: 476 at 5400

The pulls started at 3000 rpm and cut off at 5800. Torque was around 475 at the start of the pulls and didn't drop below 475 until 5200. Hp was 287 at 3000 and still 462 at 5800.

Interesting to note that the demon made the most hp, the holley 750 was very close (within 4 hp) and the 950 made about the same on the top, but gave up hp and torque lower down in rpm's. In all fairness, the 950 probably wasn't jetted right for this engine, we just threw it on for kicks. These runs were made with no accessories, so this is gross flywheel hp.
The o2 sensor was a waste of time. From what I read stoich should read 400mv and max. power should be ~820mv. We tried jetting down to 820 and lost power everywhere. Max power was made at over 1000 mv. We also tried a manifold divider and lost 1-2% hp everwhere. This is supposed to increase vacuum though (didn't measure at idle).

I know I could have made more hp with a bigger cam, but this engine idles nicely, and should be a pleasure to cruise around in. With 450 ft/lbs just off idle traction may become a problem :jester

:chevy


[Modified by 74vetteman, 10:35 PM 3/16/2002]

QuickVet

:eek: :cool:

SmokedTires

Wow those numbers look great! :yesnod: That's right in the 500hp range that I'm looking for in my next motor. All that torque down low should make for some real fun :D .

gkull

What jets do you have in the Demon? Is your cam a hydrolic roller? Did you port match your small single plane manifold?

Wasserott

Interesting numbers from a carbed motor...I have a 396 LT4 heads and intake and I had the same duration crane cam as you mention...222/230 lift 509/529 which should be very close, if not the same cam. On the flywheel dyno running just the water pump (effectively gross HP), this motor made 494 HP at 6000 and 475 ftlbs of torque from 3500 through 4500.

We moved up to the next crane cam in the powermax series (234/242) and made 531 HP and 501 Tq.

Just thought you would be interested. A good comparison to a computer controlled FI vs Carbed setup.

88-406

What's the LSA of the cam?

KM

74vetteman

Sorry guys, I haven't been on the forum for a couple of days.

88-406, I am out of town right now and don't have my spec. sheet, but the cam is an off the shelf crane hyd roller cam (224dur intake and 230 dur. exhaust). If you look on the crane web site you can see all spec's.

GKull, the best dyno torque readings were obtained with 2 jet sizes up over the factory installed jets. I believe they were 81 primary and 87 secondary. No port match, the intake was bolted just bolted on. However both intake and heads matched the gasket near perfectly.

74vetteman

Wasserott, did you have a chance to drive your 94 with either cam. If you did, which one did you like better? How does it idle?

Is it faster than your z06?

gkull

Wasserott & 74vetteman.

Your 406 has many of the same total setup as my 383. So my cam would be toned down slightly by the additional 23 cubes. I Just went with something like the next bigger Crane Power-Max cam than Wasserott. But his is also H-roller where I went solid roller. I have never dynoed mine so I was very interested to see the 396 putting out these numbers. (234/242) and made 531 HP and 501 Tq.

If you go to my home page you can see my list of motor buildups. Mine motor is very street friendly as a non-emmission car and I drove 9000 some miles last year. I have considered either a bigger cam or increasing the rocker ratio to 1.75 intake and 1.65 exhaust over my present 1.65/1.6 present ratio. I can floor my car at 2500 rpm in lockup fourth gear and it just motors away. When it gets to 4500 rpm at max TQ and the hp is coming up it really goes to 7000 rpm. What stopped me from going bigger originally is I didn't want a power range extending to high with a 7500 red line.

Monty found on his 427 SB that it continued to make more power clear into the mid 250's duration.

74vetteman

I basically followed the 406 buildup on AFR's web site in which they made 550 hp. The only differences were the cam choices (they went 230 intake and 236 exhaust vs. my 224 in and 230 ex) and intake (they used their version of a Edelbrock Victor and I used my Weiand 7530 from my previous motor).

I knew from the beginning that I was going to give up significant power with my cam choice, but maximum power wasn't my only goal. I wanted the motor to idle at 750 rpm and not to draw too much attention to itself (kind of like a sleeper). Basically, I wanted exceptional street manners and driveability at part to full throttle at any rpm.

With the hydraulic rollers I am probably limited to not much over 6000 rpm before I get valve float. My hp is over 470 from 5200 - 5600 rpm, and torque is 470+ from where we started the pulls (3000) to over 5300 rpm. If I shift at 5800 - 6k, I should always be in the meat of the powerband and not overstress my engine.

Gkull, you asked me what my jetting was in the Speed Demon post and I think I gave you incorrect information. Looking at my dyno sheets, best hp and torque was made with 82 primary and 89 secondary at 38 degrees total timing.

Question: Since my heads are good for up to .700 lift, and with 1.6 roller rockers I am only getting ~.560 lift, would you recommend me going to a 1.75 roller rocker (~.612 lift)? My heads flow best at .600+ lift. Any downside to doing this?

gkull

I'm not up on h-rollers. The additional rocker ratio and duration and lift. The down side is spring heat. I bought big 1.56 springs for .700 max lift and then shorter retainers for less pounds. So they ended up at 195# seat press. at 1.985 installed height. Crompressed spring would be in the .740 area. The whole idea is. I'm never stressing them. On a spring gauge they are within a few pounds after many miles.

You ask about the down side? Your beating the day lights out of them :yesnod: I have 7/16th & tall ARP screw in studs and you couldn't believe how much they were bent when I was putting on the stud girdle. When you need nearly 500 pounds of open spring pressure to not have valve float. I would ask comp cams what is the max pressure and lift. Are your push rods up to it or your rocker arms up to it and do you have tall enough springs.

High ratio rockers you have to figure out the push rod size. I have + .200 or 8 inch yours would be shorter because of the height of the H-rollers

Wasserott

The smaller cam 222/230 was a very reasonable cam. Not much in the way of issues. Drove very well and was a lot of fun. The big boy cam is certainly mean! Although, drivability isn't that bad considering it is so big. Not an emission at all. Very fun to drive, didn't seem to loose much down low and comes alive like mad.

The 94 is faster than the Z06 but I've run a guy with the Z against a Grand Sport 383 with the 222/230 and pulled him so it's close.