Low numbers for an 427?
Thread Starter
Teching In
Joined: Jul 2018
Posts: 46
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Low numbers for an 427? Does this seem low to you guys? Car made 467whp 455wtq
Thompson motorsports Short block built to maximize NA power for a streetcar.
Compression is 11:1
91 Fuel
4L80 -3200 stall
Ford 9 inch
2 7/8 Long tube headers, 3-inch pipe, Black widow mufflers
Sniper low profile EFI sheet metal intake with 102mm TB
Frankenstein M311 cylnder heads
Rocker ratio 7.1
Cam int/ext .629
Intake duration @0.50 240
Exhaust @0.50 256
LSA 113
ADV +4
Build sheets uploaded. Does anyone see a reason why this motor isn't making more?
The car drives good but I was expecting bigger numbers considering my old cammed/ported 243 LS6 made 32HP less on the same dyno.
Thompson motorsports Short block built to maximize NA power for a streetcar.
Compression is 11:1
91 Fuel
4L80 -3200 stall
Ford 9 inch
2 7/8 Long tube headers, 3-inch pipe, Black widow mufflers
Sniper low profile EFI sheet metal intake with 102mm TB
Frankenstein M311 cylnder heads
Rocker ratio 7.1
Cam int/ext .629
Intake duration @0.50 240
Exhaust @0.50 256
LSA 113
ADV +4
Build sheets uploaded. Does anyone see a reason why this motor isn't making more?
The car drives good but I was expecting bigger numbers considering my old cammed/ported 243 LS6 made 32HP less on the same dyno.
Last edited by cyrus buhari; Apr 27, 2021 at 11:44 PM. Reason: Adding files
TECH Enthusiast
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If you are doing the pull in 3rd gear (1:1 and not overdrive) and its hitting on all cylinders your transmission or torque converter lockup may be slipping.
Just an idea. Slip can disguise itself behind a fast ramping dyno pull, but if it is slipping the trans is not long for this world.
Just an idea. Slip can disguise itself behind a fast ramping dyno pull, but if it is slipping the trans is not long for this world.
Last edited by Kawboom; Mar 31, 2021 at 05:39 PM.
Teching In
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Posts: 18
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It does seem low. My LS3 416 made 530rwhp and 510rwtq on a mustang dyno which some people say it reads lower because it’s loaded. This was a manual in Southern California pretty warm out 80’s.
my cam was smaller 24*\24*’s than yours.
my cam was smaller 24*\24*’s than yours.
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Thread Starter
Teching In
Joined: Jul 2018
Posts: 46
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If you are doing the pull in 3rd gear (1:1 and not overdrive) and its hitting on all cylinders your transmission or torque converter lockup may be slipping.
Just an idea. Slip can disguise itself behind a fast ramping dyno pull, but if it is slipping the trans is not long for this world.
Just an idea. Slip can disguise itself behind a fast ramping dyno pull, but if it is slipping the trans is not long for this world.
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I wonder if we have missadjusted hydraulic roller lifter (ie incorrect pushrod length etc.) or a semi dead roller lifter. Take a look at plugs for a dead cylinder. What car is this in? Also I assume you mean you have a dual 3 inch exhaust. You do have two power robbers on it the Ford 9 inch and the 4L80 were these both on the car when you had the old LS6 in there? How much less TQ did LS6 make (I see the 32 hp number)? Oh yes pull the valve cover and look for Mr. Broken valve spring.
Thread Starter
Teching In
Joined: Jul 2018
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I wonder if we have misadjusted hydraulic roller lifter (ie incorrect pushrod length etc.) or a semi-dead roller lifter. Take a look at plugs for a dead cylinder. What car is this in? Also, I assume you mean you have a dual 3-inch exhaust. You do have two power robbers on it the Ford 9 inch and the 4L80 were these both on the car when you had the old LS6 in there? How much less TQ did LS6 make (I see the 32 hp number)? Oh yes pull the valve cover and look for Mr. Broken valve spring.
It's in a 1966 Nova 4 door sedan. Correct duel 3-inch exhaust. The old LS6 setup was with a 4L60. The old tq numbers on the LS6 were 387 if I recall. If it was a broken valve spring or dead lifter wouldn't I notice it in the way it drives? The car drives nice no issues other than the power.
Cream Puff
Thread Starter
Teching In
Joined: Jul 2018
Posts: 46
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Does this seem low to you guys? Car made 467whp 455wtq
Thompson motorsports Short block built to maximize NA power for a streetcar.
Compression is 11:1
91 Fuel
4L80 -3200 stall
Ford 9 inch
2 7/8 Long tube headers, 3-inch pipes, Black widow mufflers
Sniper low profile EFI sheet metal intake with 102mm TB
Frankenstein M311 cylnder heads
Rocker ratio 7.1
Cam int/ext .629
Intake duration @0.50 240
Exhaust @0.50 256
LSA 113
ADV +4
The car drives good but I was expecting bigger numbers considering my old cammed/ported 243 LS6 made 32HP less on the same dyno.
Thompson motorsports Short block built to maximize NA power for a streetcar.
Compression is 11:1
91 Fuel
4L80 -3200 stall
Ford 9 inch
2 7/8 Long tube headers, 3-inch pipes, Black widow mufflers
Sniper low profile EFI sheet metal intake with 102mm TB
Frankenstein M311 cylnder heads
Rocker ratio 7.1
Cam int/ext .629
Intake duration @0.50 240
Exhaust @0.50 256
LSA 113
ADV +4
The car drives good but I was expecting bigger numbers considering my old cammed/ported 243 LS6 made 32HP less on the same dyno.
How about Mr. Fuel Pump and also were injectors increased in size from old motor? Look like if 387 tq you picked up 70 ft pounds which is pretty good. There may be some more tq on the table but the top end HP appears to be the problem which is why I ask about the fuel stuff too.
Thread Starter
Teching In
Joined: Jul 2018
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