dyno numbers? - Chevelle Tech
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post #1 of 15 (permalink) Old Jun 19th, 17, 4:33 PM Thread Starter
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Clay
 
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dyno numbers?

so i had my chevelle dynoed today. its a 489 stroker 9:1 with scat forged crank rods and forged srp 3cc basically flat top pistons procomp 115cc heads victor jr intake aed 850dp. the only unknown is the cam. it has a nice sounding lumpy idle and its a flat tappet but i dont have specs. i didnt build this motor. i verified all the internals before i put it in but i didnt pull the cam. so my issue is it made 570rwtq but only 390rwhp. i know procomps arent the best heads but they should be good for up to 550-600hp atleast. my all iron 496 blueprint crate made 410rwhp 540rwtq and tapped out at 5200rpm. this one stopped making power at 4300. wth. is the cam the suspect here?

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66 Chevelle Malibu pro street 489 stroker
71 Nova SS Clone pro touring 496 stroker
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post #2 of 15 (permalink) Old Jun 19th, 17, 5:14 PM
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Re: dyno numbers?

Last car I saw that dyno'd 390 rear wheel HP ran an 11.66@115 MPH in a 3700 lb. 1970 442..built 455
The issue with yours is 390 RWHP at 4300 rpms...have checked to make sure you have WOT?
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post #3 of 15 (permalink) Old Jun 19th, 17, 5:40 PM
T_R
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Re: dyno numbers?

Really small cam or bad valve springs or wrong valve springs is my guess.

My 454 is set up like that on purpose. It makes like 350 hp 500 tq. Its totally done at 4500. Cam is 208/128@.050 and 475/500 lift. It's a daily driver with 3.08 gears and OD so the RPM range works great. Feels real strong on the street, but isn't actually that quick at the dragstrip.

Tom

66 Chevelle crew cab 454 FiTech /TKO 600 5 speed
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post #4 of 15 (permalink) Old Jun 19th, 17, 5:50 PM Thread Starter
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Re: dyno numbers?

the car weighs 2990 with 8 gallons of gas. 3200 w/me in it. built th400 3700 stall 4.86s full spool 9in w/33x21.5 mt sportsmans. we did check to make sure we had wot after the dyno runs but the cable is super tight and has stopped before wot on me before. i didnt think about watching it on the dyno.

The more cubes the merrier!
66 Chevelle Malibu pro street 489 stroker
71 Nova SS Clone pro touring 496 stroker
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post #5 of 15 (permalink) Old Jun 19th, 17, 5:56 PM
T_R
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Re: dyno numbers?

That engine is a horrible match for the car. Assuming everything else is healthy a bump in compression and a cam and valvespring change is probably in order.
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post #6 of 15 (permalink) Old Jun 19th, 17, 6:54 PM Thread Starter
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Re: dyno numbers?

Quote:
Originally Posted by T_R View Post
That engine is a horrible match for the car. Assuming everything else is healthy a bump in compression and a cam and valvespring change is probably in order.
thats pretty much what i was thinking. the motor is brand new. my buddy bought it for his c10 but ended up selling the truck as a roller so he sold it to me. it had 50 miles on it when i got it. for 3k complete carb to pan i couldnt pass it up. ill probably end up getting some domed pistons and a roller cam with matching springs. im gonna throw it on the dyno again first and make sure the throttle is reaching wide open during the pulls. its just strange that the tq would be 570 w 390hp.
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The more cubes the merrier!
66 Chevelle Malibu pro street 489 stroker
71 Nova SS Clone pro touring 496 stroker
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post #7 of 15 (permalink) Old Jun 19th, 17, 7:01 PM
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Re: dyno numbers?

Where did you get the head cc? Procomps are just about always 121 cc. Your compression is way down unless the heads were cut. Yea 4300 is way too low. There is more there if you can find the problem. Cam specs and valve spring specs would help.

64 Chevelle 496
64 F100 Street Rod with BBC /Chevy trapped in a ford body
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post #8 of 15 (permalink) Old Jun 19th, 17, 8:02 PM Thread Starter
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Re: dyno numbers?

Quote:
Originally Posted by StevenS View Post
Where did you get the head cc? Procomps are just about always 121 cc. Your compression is way down unless the heads were cut. Yea 4300 is way too low. There is more there if you can find the problem. Cam specs and valve spring specs would help.
i cant find the specs again for some reason. i found them when i first got the motor. 320 115cc rec port #pc3021 1.5 outside diameter springs setup for hydraulic flat tappet

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66 Chevelle Malibu pro street 489 stroker
71 Nova SS Clone pro touring 496 stroker
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post #9 of 15 (permalink) Old Jun 19th, 17, 9:07 PM Thread Starter
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Re: dyno numbers?

found em. ProComp Part number PC3021. 320cc Rect. Port BBC Heads with 115cc Open Chambers.

Valve Material

stainless steel

Valve Type

1 piece, swirl polished

Valve Length

+.250" intake, +.100" exhaust

Valve Spring Dia.

1.525", single

Spring Pressure (closed)

140lbs @ 1.900"

Spring Pressure (open)

380lbs @ 1.200"

Coil Bind

1.160"

Recommend Lift

.600"-.650" (flat tappet cams)

Retainers

4140 Chromoly steel

Valve Locks

10 degree, hardened steel

The more cubes the merrier!
66 Chevelle Malibu pro street 489 stroker
71 Nova SS Clone pro touring 496 stroker
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post #10 of 15 (permalink) Old Jun 20th, 17, 12:10 AM
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Re: dyno numbers?

If the 570 rwtq is real" then that's pretty strong, so, I'd then figure out why it's not turning more than 4300 rpm and fix that. I'd expect to see more hp with more rpm.
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post #11 of 15 (permalink) Old Jun 20th, 17, 12:37 AM Thread Starter
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Re: dyno numbers?

Quote:
Originally Posted by Rmchevelle View Post
If the 570 rwtq is real" then that's pretty strong, so, I'd then figure out why it's not turning more than 4300 rpm and fix that. I'd expect to see more hp with more rpm.
real as opposed to? the converter?

The more cubes the merrier!
66 Chevelle Malibu pro street 489 stroker
71 Nova SS Clone pro touring 496 stroker
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post #12 of 15 (permalink) Old Jun 20th, 17, 6:52 AM
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Re: dyno numbers?

Quote:
Originally Posted by searchin4a66 View Post
found em. ProComp Part number PC3021. 320cc Rect. Port BBC Heads with 115cc Open Chambers.

Valve Material

stainless steel

Valve Type

1 piece, swirl polished

Valve Length

+.250" intake, +.100" exhaust

Valve Spring Dia.

1.525", single

Spring Pressure (closed)

140lbs @ 1.900"

Spring Pressure (open)

380lbs @ 1.200"

Coil Bind

1.160"

Recommend Lift

.600"-.650" (flat tappet cams)

Retainers

4140 Chromoly steel

Valve Locks

10 degree, hardened steel
I checked 3 sets of 320cc Procomp heads. They were all over 120cc and 121 cc being a average. Nothing new these days. You should always check the chambers.

64 Chevelle 496
64 F100 Street Rod with BBC /Chevy trapped in a ford body
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post #13 of 15 (permalink) Old Jun 20th, 17, 7:17 AM
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Re: dyno numbers?

safe to assume it is a Mustang dyno?

Couple of junkers and a few clunkers.
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post #14 of 15 (permalink) Old Jun 20th, 17, 10:02 AM Thread Starter
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Re: dyno numbers?

Quote:
Originally Posted by Andy's Auto Repair View Post
safe to assume it is a Mustang dyno?
dynapack dyno. im thinking converter is some of it. but i do agree it does need more compression and a better cam for the car. i need to see what it does at the track with slicks

The more cubes the merrier!
66 Chevelle Malibu pro street 489 stroker
71 Nova SS Clone pro touring 496 stroker
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post #15 of 15 (permalink) Old Yesterday, 12:21 AM
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Re: dyno numbers?

Quote:
Originally Posted by searchin4a66 View Post
real as opposed to? the converter?
As opposed to padded #'s by the dyno operator to make their customers feel good. If those are trusted #'s I wouldn't change a thing other than figuring out why it won't go past 4300 rpm and fine tuning it.
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