Good start to dyno tuning, unexpected boost. Had to shut off at 4,500 because of boost - no intercooler, pump gas. Ordering new pulley.

Keep in mind this engine is mild in several key respects: 8.3:1 cr, and Comp 11-404 cam. Smooth idle. Total specs are:
468 cid, 8.3:1 cr, Canfield 310 heads; 2.25 x 1.88 flow ~ 330 cfm intake at .550, 11-404 cam (hydraulic flat tappet); .547/.547 lift 232/237 duration 114 degree LSA installed at 112, L78/LS6 intake manifold port matched to Canfield heads, 830 Holley by Carb Shop, Elbow carb hat (NOT K&N style) with 2" spacer/riser, Product Engineering 4400 fuel pump (460 gph), Mallory boost referenced regulator (22.4 fuel psi at 4,500 rpm) HEI ignition, ProCharger D2-R, 7.65 crank pulley, 4.75 blower pulley.

RPM C_TQ C_HP BOOST BSFC A/F-L A/F-R
3200 603.7 367.8 7.54 1.265 12.63 14.23
3300 611.0 383.9 7.98 1.275 12.55 14.18
3400 629.3 407.4 8.63 1.222 12.45 14.21
3500 641.6 427.6 9.06 1.151 12.35 14.19
3600 657.5 450.7 9.65 1.097 12.29 14.12
3700 670.9 472.7 10.18 1.041 12.28 13.99
3800 681.6 493.2 10.75 .992 12.28 13.96
3900 692.1 513.9 11.31 .951 12.38 13.97
4000 703.3 535.6 11.88 .913 12.47 14.10
4100 710.7 554.8 12.45 .876 12.54 14.16
4200 715.6 572.2 12.96 .845 12.66 14.20
4300 716.6 586.7 13.34 .820 12.75 14.26
4400 711.8 596.3 13.68 .799 12.88 14.47
4500 705.5 604.4 13.97 .787 13.05 14.59

Not sure about the wide bank to bank air/fuel ratio varience - maybe because of this style of dual plane - maybe because there is not a full divider in intake (factory style notched partial cutaway)? I'm thinking (maybe incorrectly) that the notched factory cutout of the divider is allowing the pressure from the "high" side of the dual plane to blow more fuel into the "low" side of the dual plane. I'll probably end up stagger jetting it.

Go ahead, let me know what all the above means to you. Any thoughts, criticisms, predictions on final power.

Thomas

 

Why not a single plane manifold? You could certainly handle softening up the bottom end (it may actually gain torque since you're making boost at pretty low rpms), it would flow more evenly, and you'd probably pick up some hp.

 

Monty, I never get tired of seeing your awesome engine - quite a piece you have created!

The bank to bank variation may soon be history! (just waiting for race fuel delivery) On a supercharged blow-thru carb application it ends up that it is very important to have the carb hat inlet pointed as nearly forward as possible. Mine was at ~ 40 degrees, and it was biasing airflow through the venturis, this happens on a single plane as well when the carb hat is positioned this way, only a single plane will mask what a dual plane cannot.

Both the 830 carb and this manifold were selected mainly because I already had them. If the carb hat repositioning does not do enough to get the bank to bank closer the next step would be a carb spacer, if that doesn't work then I will buy another intake. There is a lot of tuning avenues still open, that was the startup dyno check in pull.

Thomas

 

Regardless, that's a very nice engine that you've put together as well, that should be very fun without being excessive. I'll bet when you get it sorted out you'll probably pick up quite a bit more power. I saw a dyno with that supercharger model a few months ago and it almost made 800hp on 93 octane.

 

Monty, only you could say: "should be fun without being excessive"!

I don't expect to make 800 hp, maybe somewhere in the 7's. What kind of cam specs did the one similar to mine have? I know that for the most part I am only a camshaft change away from 800+hp - but I kinda think I'll have enough problems keeping this one glued to the ground, I don't know what I would do with even more power. I ordered the slowest spinning pulley ProCharger offers, but their tech guy doesn't think it will lower the boost enough. If the new pulley doesn't tame the boost, then a cam change may be the most cost effective way to lower the boost; albeit at a higher hp level :)

Thomas

 

Damn, what a bummer. Lower boost, more HP. :jester

That sounds like a sweet setup you put together.

 

I'm not sure about the cam specs, I could ask though and let you know next week.