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Estimated Horsepower (Just Curious)

If the engine has made 4000 miles intact I have some doubts about 11.5:1 compression. Keep in mind that a stock 335hp 383 only netted 280hp to start with. I drop my horsepower estimate to 325 at best, and that's probably too high.
Why do you keep saying this: intact?

Should this engine have disintegrated by now?

Again, I don’t understand your assertions. I’m not being an *** but just trying to understand the inference.
 
Why do you keep saying this: intact?

Should this engine have disintegrated by now?

Again, I don’t understand your assertions. I’m not being an *** but just trying to understand the inference.
It's all about cylinder pressure. High compression plus closing the intake valve early creates a pressure that gas can't handle. This is detonation and can lead to pre-ignition which wreck an engine. Nothing will live with constant detonation. I wouldn't buy the thing. I'd build a 383 I could live with. There's reasons why people sell these engines or cars, and the reasons usually aren't good . Devil's in the details and you don't have enough details, but do whatever makes you happy.
 
Verify with a compression test for what u actually have. At this point a bigger cam may slow it down even more. Check the timing. If it’s not pinging give it a little bit more. May take a few times. Some engines like/need up to 20degrees btdc Slow the idle speed down each time u give it a little more advance. I’d put in a decent torque converter then u will have decent drivability. Kim
 
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Curious if the group can play a guessing game regarding what HP my engine may produce. Not interested in exact numbers and don’t have access to a Dyno. So here are the details:

Block - 1969 383 HP
Bored -.040
Heads - 906 worked by Indy heads
Cam - comp cams extreme energy 477 lift
Compression - 11.5 -1
Intake - Edelbrock dual plane aluminum
Carb-Holley 850
Torque converter - stock


View attachment 1532893

View attachment 1532892




Is it even possible to make an educated gues at horsepower?

Thanks in advance,

Kurt
NOT REALLY.....The two (2) most significant factors that would effect the final number are: the vinyl top and opera windows and possibly the engine's paint color but are you requiring a NET OR GROSS HP number corrected for temperature and density? Difficult to even guess......maybe 172 hp net or 221 gross hp @ 4000 RPM....could be higher depending on IF you add a 150 hp NO2 system to the equation ......
BOB RENTON
 
NOT REALLY.....The two (2) most significant factors that would effect the final number are: the vinyl top and opera windows and possibly the engine's paint color but are you requiring a NET OR GROSS HP number corrected for temperature and density? Difficult to even guess......maybe 172 hp net or 221 gross hp @ 4000 RPM....could be higher depending on IF you add a 150 hp NO2 system to the equation ......
BOB RENTON
Vinyl top is a recent add but I believe not the period correct texture. ( would this cause the detonation issues? The opera windows are original to the car and are stamped HP so I don’t think that would be an issue. Engine color is correct although poorly done and my mechanic has singled that out as a possible Horsepower drainer.

Thanks for the laugh
 
A lot of good comments with a similar take on it, but yeah, ignore all of them and just run it ( sarcasm). I don't even like the combination of what you got in the first place, but not getting into that. And you got no power and stumble off the line, but you're going to lower gears ?
 
A lot of good comments with a similar take on it, but yeah, ignore all of them and just run it ( sarcasm). I don't even like the combination of what you got in the first place, but not getting into that. And you got no power and stumble off the line, but you're going to lower gears ?
Just chasing issue and putting right what is wrong. The gearing won’t be done till much later(if at all)
 
Get yourself a cheap borescope that can plug into your phone, pull out a plug from a cylinder with the piston near TDC, and see if it has a dome on the piston. A REAL 11.5 piston will have a substantial lump of a dome. No dome = no 11.5 ratio. (If I were you , I'd hope for a flat top.)
Once you have a better idea of what you REALLY have, you can proceed to solve your problems. (A cranking compression test can also give some good info. HOPE for less than 200 lbs) .
 
A 383 is a short stroke motor that doesn't make alot of torque like a 440. Maybe you should pull it out and open it up and see what you really have and make a few changes to make it more like what you are looking for. Maybe the cam is installed a tooth off or something like that. Hard to say without opening it up. A 268 cam is small for a 440 but maybe kind of big for a 383. There is 57 CID difference between the two.
 
The compression test will get an idea about what the pistons are. Leak down test will tell you if the rings are hammered.

Truth is you can build a very reasonable reliable 383 without breaking the bank. New stuff rather somebody's beat up stuff. If you do this you'll always know what you have without a bunch of mysteries.
 
These past few posts are spot on. Know what you ACTUALLY got, before going forward with anything.
 
A lot of good comments with a similar take on it, but yeah, ignore all of them and just run it ( sarcasm). I don't even like the combination of what you got in the first place, but not getting into that. And you got no power and stumble off the line, but you're going to lower gears ?
To the OP, I'm sorry that I did not take into account the contribution of the MSD ignition system, as it adds at least 50 additional "BLAZING" HORSEPOWER, along with a 50% increase in MPG.....you've almost have a perpetual motion machine.......definitely tell your car cruise buddies any number you feel like.....it'll keep them guessing......wanting to know all the minutia of the changes but the real secret just maybe the type of wax used.........?????
BOB RENTON
 
Curious if the group can play a guessing game regarding what HP my engine may produce. Not interested in exact numbers and don’t have access to a Dyno. So here are the details:

Block - 1969 383 HP
Bored -.040
Heads - 906 worked by Indy heads
Cam - comp cams extreme energy 477 lift
Compression - 11.5 -1
Intake - Edelbrock dual plane aluminum
Carb-Holley 850
Torque converter - stock


View attachment 1532893

View attachment 1532892




Is it even possible to make an educated gues at horsepower?

Thanks in advance,

Kurt

WAG, <335hp. Baby cam (low rpm) with old school dual plane intake are hp killers IMO.

Off the shelf cam specs,

 
To the OP, I'm sorry that I did not take into account the contribution of the MSD ignition system, as it adds at least 50 additional "BLAZING" HORSEPOWER, along with a 50% increase in MPG.....you've almost have a perpetual motion machine.......definitely tell your car cruise buddies any number you feel like.....it'll keep them guessing......wanting to know all the minutia of the changes but the real secret just maybe the type of wax used.........?????
BOB RENTON
Carnuba of course.
 
In any thread, it's always nice to have good humor
1696291090534.png
 
I agree with what was mentioned several times, they may have been called " 11.5 to 1s"
But in your current state are likely 10- 10.5.
I ran a very similar combo that was previously built with the L2293F's and 906's ,about a 280/480 cam and it ran fine at the track on premium. About 12.90s, so maybe in the 400ish area.

To answer the original question.
 
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