OK, I know the plug wires look tacky but I didn't have my wire seperaters with me.... Even so, I had a blast at the dyno today. The mill is a conservative pump gas(9.4/1), solid flat tappet, oval port 496. Made 10 pulls. Best numbers were:

586HP @ 5700
600TQ @ 4600

I would've REALLY liked to get that magic 600HP number, but it was raining off and on so the air here wasn't that great...
I'm pleased with the results for what it'll be used for.

http://www.chevelles.com/showroom/Purs/dyno-ready.jpg

Thanks for everyone's insight, advice, and patience while I was gathering parts and making decisions on this combination.

Glad you had fun, dyno day is always cool. A little more cam will get you that 6000 hp. Normally when the tq and hp #'s are that close together the motor wants more cam.

What are the engine specs?

when you say more cam do you mean lift or duration?

I'm trying to educate myself on reading all these dyno sheets. At least it's something I can spend some time on and not money for awhile....

Looks like you hit your numbers pretty good for what you were lookin for.
Are those the ported 781's you told me about?
As I recall they flowed about 310 or so at .700 which is very good for a 781 type head if the lower numbers are good too.
Also if you used the Z33 you had, a cam with a little more lift & duration, especially on the exhaust side on wider centers will put you over that 600 mark.
Big engines like cam,,,
graemlins/beers.gif

Nice!! graemlins/thumbsup.gif

thanks Chris. Mike, yes it has the 781's. The cam is a Z-55 (.590/.590 254@.050) and I agree, a little more cam wouldn't hurt. Me and my builder were really shooting for midrange torque (over PK HP) It shows 554 ft/.lbs of TQ at 3900 (where the dyno starts reading) and stays over 500 all the way to 6000. That's good isn't it? What's strange to me is that once we figured out how much timing this engine liked we settled in the 580's on the HP, but the more we kept jetting it up the more torque we made and HP stayed the same... how does that work?

For all you carb guys, I was running a custom worked Demon 850. For the last pull we put on a Holley HP 1000 (or 1025?) and the engine made 6 more ft/lbs of torque but lost 1 HP...

Purs ... Congrats , great torque numbers , what were your BSFC and timing .... nothing like a good day at the dyno smile.gif

Purs,

Those are great numbers for a low compression engine. Should be one very fun street/strip car/engine.

Where did you have it dynoed?

EXCELLENT numbers graemlins/thumbsup.gif

Is that a super sucker in the picture? Did you make any pulls with that off? If so was there much of a difference? Nice numbers should be a blast.

Mike

CND SS, We settled on 36* total timing. According to my dyno sheet the BSFC #'s were in the .6's all the way down. Is that bad?

DragRacer, Speed Equipment and Machine just outside of Abilene. Super Flow 901

K20mike, yes it's a HVH 1" Supersucker 4 hole to open spacer. All pulls were run with it.

A BSFC of 0.6 is high and usually means you're running rich. A perfectly tuned naturally aspirated BB should be in the mid-high 0.4's, maybe hitting 0.5 at high rpm. Super/turbo charged or nitrous runs richer for safety, about 0.6.

Purs excellent numbers glad everything worked out ok.You have a gas friendly 600/600 engine at 9.4 comp. graemlins/thumbsup.gif

Originally posted by Purs:
CND SS, We settled on 36* total timing. According to my dyno sheet the BSFC #'s were in the .6's all the way down. Is that bad?

DragRacer, Speed Equipment and Machine just outside of Abilene. Super Flow 901

K20mike, yes it's a HVH 1" Supersucker 4 hole to open spacer. All pulls were run with it. BSFC .6 ?? Someone help me out here I'm not that dyno savy ... do you mean .60 ?? if so then yes very rich and the little I know most dyno operators like to keep it around .42-.45 for safety if you had jetted down or bumped timing you would have cracked 600hp IMO .....it looks like I made same error on my dyno day we were .45-.46 but at 39* pbly should have been around 36 but low 40's high or ,39-.38 as I understand it ...some more current software on Superflow 901's take BSFC to three digits for really fine tuning .....
Thanks for the info it's help me further understand my results and know better for next time where to tune ... "if" I'm understanding this correctly , sure nice to share info here.


FWIW after I hit my best number I installed a HVH 1" 4 hole super sucker with no improvement and some loss of torque in mid range ...on RPM Airgap ...... But every motor different so only my experience.... going to try it on the street it may improve part throttle response etc etc

Bill


Bill

Purs,

Congratulations on a what appears to be an excellent combo. 600ft lbs will have that Chevelle tearing up the pavement. When are you planning to take it to the strip? Keep us posted graemlins/thumbsup.gif

Fabulous numbers for that combination. With the dual plane intake on your engine combination I think that the simple addition of an open 1" carb spacer UNDER the Super Sucker would have edged you closer to the 600 mark.

The torque curve from a 4.25" stroke is lots of fun. The first itteration of my 496 showed 495 tq @ 2,500 rpm, peaking at 602 @ ~ 4,800. Since then I've gone bigger on the cam and changed out an Edlebrock Victor Jr. intake for a vintage Edelbrock C454 dominator flanged dual plane (with a 1/2" 4 hole on top of a 1" open spacer). No dyno or drag passes on my new combo, but the ass-o-meter gives it high marks smile.gif

Thomas

No dyno or drag passes on my new combo, but the ass-o-meter gives it high marks Is that an Autometer gauge? :D

Thanks Ken for compliments. The motor IS going in my '68, just not in my chevelle. You see, it left for Florida about 3 weeks ago for a new home. I REALLY wanted to find a '66 or '67 chevelle but couldn't justify spending that kind of money right now with a 6, 3, and 7 month old.... SO, this '68 will have do for now. The plan is for some quiet mufflers and ralley wheels. Sort of the whole "wolf in sheeps clothing thing...."
http://www.chevelles.com/showroom/Purs/1.jpg

Rest assured that someday I'll have another chevelle. graemlins/hurray.gif

I think Auto Zone has those ass-o-meters on sale this week!
Mine's gone bad so I guess it's time for a new one.

Randy

I tried a super sucker on my 454 chevelle. no dyno pulls, but it made the car soggy at the track. so I took it off. A buddy put one on his 454 thats nearly identical to mine. it picked up 29 hp on the dyno. He has never made a pass without it on to see if it makes a difference at the track though.

Ok , I have to ask, whats a super sucker? Keep it clean boys.
By the way, great numbers Purs graemlins/thumbsup.gif

Super sucker (http://www.highvelocityheads.com/ss.htm)
Pretty clean :D

Originally posted by blumont:
Ok , I have to ask, whats a super sucker? Keep it clean boys.
By the way, great numbers Purs graemlins/thumbsup.gif Jerry if your planning to dyno your engine and want to try a Super Sucker let me know I'll send you mine to try .... did not help my motor but every combo different Bill