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Old 02-01-2005, 10:10 PM
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Long Awaited 400 SBC Dyno Results

I've finally got the results for the 400 SBC that I have been asking all kinds of questions about lately, from differences in valvespring pressure, to crankshaft and block reliability, manifold porting etc. I thought I would post the dyno numbers to show what motor I produced with some of the help and insight I received from people on this website. I have also received PMs from people interested in the output from this particular build. I got this done yesterday, at the expense of $640 (CDN), but the guy I built it for sure had a big grin on his face when he seen the numbers. Although it was a tad shy of my expectations, he was thrilled with the output and promised to do some rubber donuts in front of my shop in his truck when the snow is gone.

So here it is... I cannot get my scanner working for the actual dyno sheets, so I typed it out instead in summary form, since there is a TON of information from the dyno (some of which I don't really know), and it would make for a long night of typing to report it all...

------------------------------------------
Lee Brothers Automotive - performance specialties

- Dynamometer test session results for 400 Small block Chevy


-Ambient air temperature: 18.9*C
-Ambient air pressure: 101.9 kPa
-Ambient humidity reading: 42%
-Fuel Type: Gasoline
-Fuel Octane rating: (unknown)
-Fuel delivery method: Carburetion

Gross power output readings:

RPM...............PWR(HP)...............TRQ(FT-LBS).............MAN PRS(PSI)
2000................165........................433 ...........................14.56
2250................190........................443 ...........................14.55
2500................216........................454 ...........................14.54
2750................242........................462 ...........................14.52
3000................270........................472 ...........................14.50
3250................300........................485 ...........................14.47
3500................328........................492 ...........................14.45
3750................356........................498 ...........................14.41
4000................381........................501 ...........................14.38
4250................406........................502 ...........................14.34
4500................427........................499 ...........................14.31
4750................446........................493 ...........................14.26
5000................453........................476 ...........................14.21
5250................463........................463 ...........................14.15
5500................457........................437 ...........................14.11
5750................468........................427 ...........................14.10
6000................435........................381 ...........................14.07

There was a bunch of other stuff it read, like approximate CFM airflow usage, efficiency of overlap, efficiency of head flow, intake manifold restriction estimates, exhaust manifold restriction estimates, etc. but this is all sensitive to the engine parameters that were entered for the dyno test, and as such they are computer generated numbers and should be taken as credibly as Dyno 2000 numbers.

Here is the engine build for this test:

SBC 406
10.5:1 compression
Speed Pro forged pistons with -10cc dish (he wanted pump gas)
Scat forged 5.7 rods
Scat cast 9000 series crank
Clevite 77 bearings
Mildly ported Edelbrock Performer RPM heads 252cfm intake, 191 cfm exhaust, 64cc chambers
Comp Cams solid XS268 cam, 230/236 @ .050, .488/.501 lift, 110 LSA
Crane Cams Pro Street Roller Rocker Arms
Edelbrock RPM Air Gap intake
750 Mighty Demon Carburetor
1-3/4" Hooker full length headers
Mallory Performance HEI Ignition with Accel 8mm plug wires, 36* total timing
Stock Oil pump with Moroso oil pan with baffle
8" harmonic dampener



I would have adjusted the carb some more, but the price of the operation severely limited my time. All in all it produced a pretty strong street motor, although short of the 500HP I was expecting, guess it shows that 500 HP is a lot harder to attain than one might think. It's possible the readings may have been slightly higher had I tested this motor at sea level in better air, as I currently reside at about 2800 ft elevation. I noticed the torque and HP peaked at relatively low RPM, calling into question the use of a bigger cam. However I was to use the stock stall for this build (truck), so I would have been giving up a lot of low end going much bigger.

I can surely use this as a basis for another 400 SBC project I have in the works, perhaps upgrading to a solid roller cam, a victor jr intake, and a bigger cam with a higher stall to get to the 500HP mark.

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Old 02-02-2005, 05:56 AM
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Nice numbers, and it looks like it'll be very streetable. I just used a XS268 solid lifter cam in my Son's 331 buildup last fall but we haven't had it in the car yet. I'm hoping it'll pull to 6800ish in the bored 327. It sure sounds nasty running on the engine test stand!
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Old 02-02-2005, 04:39 PM
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That is really interesting. Do you happen to know how much those heads cost in the end after the mild port job? Thanks for taking the time to post this info.


Adam
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Old 02-02-2005, 07:54 PM
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They cost no more than the price you would go and buy them at. I just did a basic pocket port to them at the expense of only my time. I guess if you add the charge of flow testing it would bump the cost up by $75 CDN, but I choose to not include that amount since it is not a tangible aspect of the heads themselves.
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Old 01-02-2006, 01:54 PM
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I'm putting a XE 262 in my 406 that's going back in my boat. I just got the Desktop Dyno(ver. 4.20) and when I ran the #'s It gave ridiculously high hp/torque outputs. I can use your dyno results and lower all the numbers(espacially the hp/torque rpms) and get a nice boat motor.

Thanks,
Charlie
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Old 01-02-2006, 04:42 PM
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good job holy **** man, i would hat to face you on line atleast untill 5700 rpm, wow that thing has some low end tq. i hope your frame can handle it

tq. monster, excellent job

J
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Old 01-06-2006, 11:25 PM
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Wow...great torque curve!! Have you used or witnessed the Scat crank and rods in a HP drag engine(say 800 horse 406 at 7500)?
Thanks,
Larry
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Old 01-07-2006, 07:32 AM
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Great job man.

500 was a bit optimistic.

In all reality a good pump gas engine with nice alum heads and a roller cam will net approx 1.2 HP per cubic inch at the RPM's you are running.

Did you get BSFC numbers?
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Old 01-07-2006, 07:52 AM
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thanks for the dyno test.its a great motor with awesome tork.good luck with your toy.
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Old 01-07-2006, 10:19 AM
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To compare apples to apples it would be nice to see the figures corrected to either STP dyno correction or SAE corrected. Then they could be compared against typical mag testing (STP dyno correction) or new car published figures (SAE) absent intake and exhaust installation.

I am sure the figures (which appear uncorrected) are high as kPa pressure readings are above atmospheric.

No matter, even if the corrected numbers come in around 400 it's still a great street motor.
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Old 12-23-2006, 05:40 PM
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I really think that 500 horse number is attainable with some time spent tuning and playing on the dyno. But the results you got a totally real. I love those 400's. Big cubes-light weight-lots of torque.
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Old 12-23-2006, 08:10 PM
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We did a 383 last year with simlar torque numbers but a little less horse power.
http://www.chevelles.com/forums/show...highlight=DYNO
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Old 12-24-2006, 07:27 AM
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I found this and thought it was interesting. It came from here.

http://www.hotrodders.com/forum/newr...ote=1&p=737710


Here's an interesting bit of trivia; below 5252 rpm any engine's torque number will always be higher than its horsepower number, and above 5252 rpm any engine's horsepower number will always be higher than its torque number. At 5252 rpm the horsepower and torque numbers will be exactly the same.
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Old 12-24-2006, 06:14 PM
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wow, who gave this thread c.p.r.? i havn't seen this thing in a long time is the original poster even a member anymore?

-J
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Old 12-25-2006, 03:46 AM
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These numbers look like a copy cat of what I got out of my SBC 400 on the dyno. Im using a Lunati Solid cam and AFR Heads, but it pulled like a rape ape into 6300 rpm. Then I told the Dyno operator to let off the throttle before he blow my engine that I just finished building.
4300 502 tq
5800 464.9 hp

here is the dyno sheets if you want to see the complete results, however check out how 2* in timing made a great difference, but all we did was change from a vac sec to his dbl pumper and move the timing. I think I can get that 500hp will a little more tuning plus the rings sealing and all the parts losing up.

DYNO sheet # 1967
http://rides.webshots.com/photo/1164...57560426vyOmsc
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