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#1
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'78 W72 400 Dyno Results
We thought we'd share this in the Street Forums. Dan had a good dyno session last week with the W72 400. He rebuilt the original numbers matching engine with .040" over Icon forged pistons w/4.5 cc valve reliefs that are .005" out of the hole and with .045" x 4.328" Felpro head gaskets to provide .040" quench depth. The 6X-4 heads were minimally cut for trueness and measured 92.45 cc's average for an final static compression ration of 8.75 to 1. Dan replaced the cast rods with forged Eagle H-beam rods. New 1-pc valves (2.11/1.66) with CC dual springs were installed. He had a Summit 2800 cam (204/214/112 @ .422"/.444" is pretty close to the original W72 cam specs) on hand, so was utilized, along with new 'old' Crane hydraulic lifters along with a new Melling 60 psi oil pump. The one modification/upgrade was the use of factory D-port ram air exhaust manifolds with the 2.1" outlets with Pypes 2.5" mandrel headpipes. The original 17058263 Q-jet on the factory cast iron intake with the EGR system and plumbing were reinstalled.
The base (and all) pulls were made with 42 degrees total timing in by 3000 rpm, 45 primary rods/74 jets/CH secondary rods on an I hanger. The 3rd (and best) base pull made a corrected 360.3 hp @ 5000 rpm/456.1 lbft torque @ 3600 rpm (351.2 hp/444.5 lbft uncorrected). The correction factor was a low 1.026 as the weather conditions were very good...low humidity, high barometer, and cool temperatures (65 in dyno cell). After rejetting the carb to 40 primary metering rods/72 jets/DA secondary rods on an 'I' hanger (same total timing at 42 degrees), employing the 'big' dyno room dumps for the headpipes, and installing the air cleaner base, the max hp jumped to 371.4 hp @ 5000 rpm/459.2 lbft @ 3600 rpm (362.0 hp/447.6 lbft uncorrected) on the final pull (#14). The highest torque reading was on pull #13 at 460.3 lbft. This engine surprised us by exceeding our first 350 hp/450 lbft prediction. Pretty good for a smog motor! Dennis |
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#2
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That’s very nice!
Surprising numbers seeing as it was not even 9 to 1 compression and it was driving its own water pump in the test! To make that level of power it would seem that intake flow wise the motor was using 180 cfm out of the about 208 average cfm that those heads flow. I would be interested in what muffler might have done to those numbers in regards to that 8.75 comp! Congrats and thanks for posting it!
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#3
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Nice build, thanks for sharing
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#4
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Nice build! About what I have in the 81 except a Peformer intake and a 73 Qjet.
Big WP pulley!
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#5
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Very nice!
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#6
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Nice numbers! Just goes to show how well a basically stock engine with the right combo of parts can run.
I'm curious why you used 42 degrees timing and didn't change or experiment with it? That seems high...?
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
#7
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..good results but seems for me a but high for such a tame cam ....
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#8
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Dennis,
Thanks for sharing some more information. Dennis posted this in the race section. Quote:
Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
#9
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Interesting..I've always thought those engines were underated..many enthusiasts get hung up on the low net hp ratings. Also combined with the lazy gearing most came with from the factory. I've always found on those low compression engines cranking the timing up in that 40 degree total or higher range works well.
My son's car with a worn out stock 400 with 342 gears mild convertor full weight ac car dips into the 13's easily.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#10
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Really impressive numbers for that small cam and low compression
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Chris D 69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60' |
#11
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I think the test DA was really good as well...I'd like to know more details on the cam install??
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#12
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Quote:
Dennis |
#13
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Dennis |
#14
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Dennis |
The Following 2 Users Say Thank You to SD455DJ For This Useful Post: | ||
#15
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Quote:
Dennis |
The Following 2 Users Say Thank You to SD455DJ For This Useful Post: | ||
#16
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Thanks Steve25, PAUL K, Skip Fix, and dragracerx2813 for the compliments!
Dennis |
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#17
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Quote:
Dennis |
#18
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That would make a great daily driver,thanks for sharing
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#19
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Hmmm. And 400`s don`t make torque.
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#20
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Figure the NHRA stockers with a 78 motor are running mid 11s!.
The Summit cam in the 400 in the 81 degreed right on "dot to dot". I built the 81 car out of someone else's stalled 301T to 455 SE TA and extra parts I had collected from the 78 (HO oil pan) for the kids to drive to high school. So I did not want it to have too much HP! Son never got used to a car with a carb and a choke in the cold! Put a Shaker hood and extra Shaker scoop on it this summer.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
The Following User Says Thank You to Skip Fix For This Useful Post: | ||
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