Very Disappointed
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Senior User
Joined: Jan 2012
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From: Antelope, California
Very Disappointed
Heres the story. About 4 months ago i had the 360 in my F250 rebuilt. I had alot done to it and sunk around $7k into it all together. Last week i finally got the correct pushrods and everything was coming together. Today i went in to a friends shop and hooked it to the dyno. Before starting anything he asked me if i had a guess. I told him, with a huge smile, that i had no idea but expected the HP to be in the 350-400 range and the TQ to be closer to 450+. On the first run i blew the tread off the back tire and had to get my only spare put on. On the next run everything worked flawlessly but we only got it to 4600 rpms before it coughed and had to back off. The next run went to 4700rpms and that was it. I looked at the screen in complete disbelief, running 4700rpms hitting 104mph and a dismal 380 TQ and 279 hp at the wheels. I am dumbfounded. Neither of us expected to see what the screen revealed. I still cant believe it and im ready to sell this dam* truck now. Needless to say im really bummed and i had to tell someone.
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From: Alton, MO
Pretty rough to say anything without knowing what you have done to the engine. I would think 400 hp along with your guessed torque would be expecting quite a bit out of a 360. I have 100 more cubic inches & am probably between 350 & 400 hp.
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Joined: Aug 2008
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From: pahrump nv
I spent 2500 and my 5.0 on the engine dynoed 498 at 4500 rpm but the only thing stock is the block that being said fe motors are not high performance nothing with out a set of good flowing heads as any ford engine all have asthma have the the heads ported and polished or aftermarket... heads can be bolt on 50 to 60 hp on a stock motor . does n e one make aftermarket heads for 390 360 motors?
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I spent 2500 and my 5.0 on the engine dynoed 498 at 4500 rpm but the only thing stock is the block that being said fe motors are not high performance nothing with out a set of good flowing heads as any ford engine all have asthma have the the heads ported and polished or aftermarket... heads can be bolt on 50 to 60 hp on a stock motor . does n e one make aftermarket heads for 390 360 motors?
There's no replacement for displacement.
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Thread Starter
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Senior User
Joined: Jan 2012
Posts: 169
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From: Antelope, California
All the mods are listed in my garage, but its a modified 390 now bored .030 over with forged pistons and ported heads, oversized stainless valves and big cam, roller rockers etc. Check it out if you want to, like i said, its all in my garage
Posting Guru
Joined: May 2010
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From: Alton, MO
Have you read this?
http://www.network54.com/Forum/74182.../Reversion+Dam
http://www.google.com/#hl=en&sclient...w=1024&bih=685
Lead Driver
Joined: Aug 2003
Posts: 7,592
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From: **** hole San Jose ca.
I look in your garage and it look like you put the 7k all over the truck and not just the motor. Unless you had a hurry shop do it all for you. You may just need to have it tuned right & jetted, Plus the motor may still be a little tight. But sounds like somethings not right, sure you'll find what you did or the problem...
orich
orich
Fleet Owner
Joined: Dec 2009
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From: NorCal
Waitaminute..... you ran the rig on a chassis dyno, right? Those results can vary widely from dyno to dyno PLUS... that's rear wheel horsepower. The numbers you hear from people may result from an engine dyno or a chassis dyno so it needs to be an apples to apples comparison.
An engine dyno does not experience parasitic driveline losses like a chassis dyno. For example, an auto tranny is inherently less efficient than a manual transmission which transfers more HP to the rear wheels. Using the rule of thumb of 20 to 25 percent for parasitic losses, your estimate of 350 is in the ballpark for gross HP at the crank. An 380 ft.lbs. at the rear wheels is also decent.
The RPM is only 4700? That's low if, as I am assuming, it has a higher lift cam. However, ya might have found the line between lift/duration and how much the stock heads can handle.
An engine dyno does not experience parasitic driveline losses like a chassis dyno. For example, an auto tranny is inherently less efficient than a manual transmission which transfers more HP to the rear wheels. Using the rule of thumb of 20 to 25 percent for parasitic losses, your estimate of 350 is in the ballpark for gross HP at the crank. An 380 ft.lbs. at the rear wheels is also decent.
The RPM is only 4700? That's low if, as I am assuming, it has a higher lift cam. However, ya might have found the line between lift/duration and how much the stock heads can handle.