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Finally put the 489 motor on a dyno…..

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5.5K views 50 replies 16 participants last post by  65cayne  
#1 ·
Fresh rebuild of my old BBC. A long time in the making!
I was expecting and hoping for 525HP and TQ.
It’s a 489 build
GM ‘215 casting, iron, oval port, closed chamber heads. Worked over a bit with 11/32” valves. 2.25/1.88 valves.
Compression is just 9.4:1.
Cam is a SR, Jones 245/252, .681/.680 lift.
Installed on a 108 ICL, 112LSA that he spec’d for me based on my combo, head flow and the fact that I said it has to be streetable
Air gap, oval port dual plane intake with 1” open spacer. (For my port to run PCV)
Holley HP 80496-1 carb that was worked over by Nickerson Perf.
Dyno’d at Nickerson Performance.
Made the best power at 40* total timing.
Had great oil pressure throughout the pulls. Tuned the AFR to about 12.9.
Best pull was 580HP at 5752RPM and a nice 605TQ at 4620 RPM.
It has gobs of low end torque.
We took it to 6200 RPM and the HP was still at 573. I was surprised there was no steep drop off.
Image
 
#5 · (Edited)
VORTECPRO said:
What was the uncorrected HP?
Click to expand...
I forgot to ask that. I'll e-mail him now. Hopefully the data is still there and he can pull it for me.

VORTECPRO said:
What did your valve springs set up at?
Click to expand...
Isky 9975-RAD Installed at 1.975". 210# seat, 550# open, .105" from coil bind.
For this cam and its ramp profiles, it’s what was recommended for seat pressure.
 
V
#6 ·
JIM said:
I forgot to ask that. I'll e-mail him now. Hopefully the data is still there and he can pull it for me.


Isky 9975-RAD Installed at 1.975". 210# seat, 550# open, .105" from coil bind.
For this cam and its ramp profiles, it’s what was recommended for seat pressure.
Click to expand...
When I see the BSFC jumping around like that @ higher RPM I always suspect valve float, take a look at the valve tips.
 
#13 ·
DAY'UM! Nicely done. and here folks were saying the 215 CC didnt prefer much timing lead. WRONG.

At what RPM did your TQ peak? Mine was around 4300 rpms, yours looks maybe below 4000 which is cool!
 
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C
#16 ·
I'd tighten the lash down on the exhaust side in .004" increments until it stops making more power. That's if you want too. Your goal has been met in power but it has a bunch more in it.
 
#21 ·
I actually did that. Tightened the exhaust lash from .016” down to .011” and it lost power and torque across the entire range.
Overall average was down 9 HP and 8 TQ.
Dyno guy wasn’t surprised but I was. I thought for sure the extra duration and lift would help these heads.
 
C
#26 ·
Sweep pattern looks good. Referencing the lock split/gap it is narrow which is very good. No sign of float on that one. Shrouding might be causing it. If so no worries you got your number...go have fun.
 
#27 ·
Here are a couple pics of the head. They have been laid back slightly by the spark plug on the exhaust side. Not the typical appearance of the closed chamber bathtub shape. That’s why the chambers are about 115ccs.
 
#29 ·
.
CamKing said:
Oh, ye of little faith ;)
I wish you pulled it down to 3,000rpm
Click to expand...
Yea, I wished we had also but he is and old school guy. Says it’s not necessary to load the engine down that low. He made a few tests in the idle to 3000rpm range for tuning the air bleeds and jets. Once he saw where peak power and torque was, he kept the pulls in that range.
End of the day I should have asked for a 3000-6200 pull. But oh well.
 
C
#31 ·
Disreguard what I said as now I see heads have been ported. That can change drastically what duration split is needed.

Its almost impossible to load a waterbrake dyno below 3500 rpm that what you don't see many dyno sheets below 36-4000 rpm and most shops can afford an AVL dyno at 7 figures.
 
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