Safe HP/TQ Level For Numbers Matching Block?

[TorRed]

I know I should pull & store my Roadrunner's numbers matching 383, but what I will be doing instead is building it to a 'safe' power level and just not abusing it unnecessarily; no burnout contests, limited track time, mostly cruising and 'feeling the power' from time to time.

At what power levels am I starting to exceed a level safe for the block? I plan on getting it professionally built with good machining, etc. but don't know if 450 or 500 HP/TQ is pretty much the limit without block stiffening, better caps, lighter internals, etc. Depending on the power target, I may leave it stock stroke or go with a 3.75" for 432 C.I. unless that would push the motor too hard. Same with heads; either stock or CNC Ported Stealths.

The Durango has 710HP and the wife's Mustang GT Performance Pack has 486 so I'm thinking something close to the Stang should be about right. I'd especially appreciate opinions from longtime builders here on the forum.

Thanks,
Jim

 

[autoxcuda]

500 hp easy. 4" stroke is fine. Forged crank for extra insurance since numbers block.
The modern piston and rods are much lighter than stock and help with reliability too. Come with way higher quality ARP rod bolts.

 

[RemCharger]

I had 600 in a stock stroke. 13:1 , heavy trws, 7200+ 383

 

[TorRed]

500 hp easy. 4" stroke is fine. Forged crank for extra insurance since numbers block.
The modern piston and rods are much lighter than stock and help with reliability too. Come with way higher quality ARP rod bolts.

Based on this, it would seem a lighter internals 432 is less stress on the block than a heavier 'stock' 383 rotating assembly even with the extra HP/TQ it would produce. Does that sound right? Thx

 

[TorRed]

I had 600 in a stock stroke. 13:1 , heavy trws, 7200+ 383

I know people can get some insane power out of these motors, but no way am I doing that to this 383. Would definitely build another block first. Thx

 

[R413]

You won't have too much horsepower at 450.

The more RPM it glues the more stress on the block. They crank the webbing around the main bearings.

Have the cylinder walls sonic tested to see how thick they are and the core shift.

 

[RemCharger]

I know people can get some insane power out of these motors, but no way am I doing that to this 383. Would definitely build another block first. Thx

That information was more a verification that 450 is a complete non concern. I wasn't trying to suggest you would build such a thing.

 

[6PKRTSE]

The lighter than stock internals and the tune are they keys to making it live if you are spinning it to high RPM's often. I have several different builds all over the spectrum from one 440 making around 450 h.p. with over 60,000 Miles on it. Another 383 around 400 h.p. that is sprayed to over 600 h.p. Another 440 that is stock and around 285 (smog motor) sprayed with another 175 shot.

 

[Runcharger]

Safe to 600HP if properly built. Good on you for going the original 383. Something about 440 swapped into Road Runners that just doesn't add up.

 

[autoxcuda]

Safe to 600HP if properly built. Good on you for going the original 383. Something about 440 swapped into Road Runners that just doesn't add up.

And we just temporary keepers of these cars. These numbers blocks set aside seem to magically disappear over time.

 

[autoxcuda]

I know I should pull & store my Roadrunner's numbers matching 383, but what I will be doing instead is building it to a 'safe' power level and just not abusing it unnecessarily; no burnout contests, limited track time, mostly cruising and 'feeling the power' from time to time.

At what power levels am I starting to exceed a level safe for the block? I plan on getting it professionally built with good machining, etc. but don't know if 450 or 500 HP/TQ is pretty much the limit without block stiffening, better caps, lighter internals, etc. Depending on the power target, I may leave it stock stroke or go with a 3.75" for 432 C.I. unless that would push the motor too hard. Same with heads; either stock or CNC Ported Stealths.

The Durango has 710HP and the wife's Mustang GT Performance Pack has 486 so I'm thinking something close to the Stang should be about right. I'd especially appreciate opinions from longtime builders here on the forum.

Thanks,
Jim

496"
CNC ported Stealths 80cc
Edelbrock RPM
850 DP
4.25" stroke kit with -20cc dish piston for 10:1 compression w/.039 gasket. A few points less compression would be a little safer (esp w/California 91 octane)
240 to 250 @50, .515 to .530, 110 CL, range solid or hyd. -call Bullet Cams
1 3/4" or 1 7/8" TTI headers.

I think this will get you close to 500 HP. Should be around 1hp/1cid plus. And pretty streetable.

 

[TorRed]

That information was more a verification that 450 is a complete non concern. I wasn't trying to suggest you would build such a thing.

Trust me, I got that and at one time I might have gone the super high HP route, but as I get older so does the car and I began to value what's there for that very reason. Thx

 

[dfrazz]

496"
CNC ported Stealths 80cc
Edelbrock RPM
850 DP
4.25" stroke kit with -20cc dish piston for 10:1 compression w/.039 gasket. A few points less compression would be a little safer (esp w/California 91 octane)
240 to 250 @50, .515 to .530, 110 CL, range solid or hyd. -call Bullet Cams
1 3/4" or 1 7/8" TTI headers.

I think this will get you close to 500 HP. Should be around 1hp/1cid plus. And pretty streetable.

The original 383 in my '68 Charger has a similar 496 stroker build
440 Source 4.25 stroke kit
Comp Cam Xtreme Energy hyd roller 230/236 @ .50, .541/.537 lift (part #23-711-9)
Comp magnum roller rockers 1621-16
Holley 80770 Street Avenger 770 cfm carb
Eddy CNC heads
383 performer intake - thinking of upgrading to an AirGap if hood clears
TTI 1 7/8" headers

Very streetable and with 3.55 gears it jumps off the light, does burn outs on demand but you can also cruise on the highway making it a great all around performance engine.

 

[TorRed]

The original 383 in my '68 Charger has a similar 496 stroker build
440 Source 4.25 stroke kit
Comp Cam Xtreme Energy hyd roller 230/236 @ .50, .541/.537 lift (part #23-711-9)
Comp magnum roller rockers 1621-16
Holley 80770 Street Avenger 770 cfm carb
Eddy CNC heads
383 performer intake - thinking of upgrading to an AirGap if hood clears
TTI 1 7/8" headers

Very streetable and with 3.55 gears it jumps off the light, does burn outs on demand but you can also cruise on the highway making it a great all around performance engine.

The 4.25" crank was my plan until I became concerned about longevity / saving the block. I already have a very similar Lunati Hydraulic roller I'd like to use and would be interested in how much 'lope' you have on the 496"? I've been told our cams are on the tame side for these larger stroker motors but since I'm also adding Classic Air that may not be such a bad thing. Thx

 

[dfrazz]

The 4.25" crank was my plan until I became concerned about longevity / saving the block. I already have a very similar Lunati Hydraulic roller I'd like to use and would be interested in how much 'lope' you have on the 496"? I've been told our cams are on the tame side for these larger stroker motors but since I'm also adding Classic Air that may not be such a bad thing. Thx

I have Vintage Air on my Charger too and it works great! I don't feel it has too much lope, just a nice sounding big block stroker.

 

[TorRed]

I have Vintage Air on my Charger too and it works great! I don't feel it has too much lope, just a nice sounding big block stroker.

That is awesome, thanks for sharing! I've got 2.5" Dynomax Ultraflos and planning on using TTI exhaust which it looks like you might too? And that's the perfect exhaust note in my mind, not loud but has that deep "move the air" quality that screams power, not noise. Congrats!

 

[dfrazz]

That is awesome, thanks for sharing! I've got 2.5" Dynomax Ultraflos and planning on using TTI exhaust which it looks like you might too? And that's the perfect exhaust note in my mind, not loud but has that deep "move the air" quality that screams power, not noise. Congrats!

Yes, I have the Dynomax mufflers with an X pipe. I prefer an H pipe has it is more of a deeper tone but this is how my car came so it will stay like this for now.

 

[autoxcuda]

The 4.25" crank was my plan until I became concerned about longevity / saving the block. I already have a very similar Lunati Hydraulic roller I'd like to use and would be interested in how much 'lope' you have on the 496"? I've been told our cams are on the tame side for these larger stroker motors but since I'm also adding Classic Air that may not be such a bad thing. Thx

What are the specs on the Lunati cam?

 

[TorRed]

What are the specs on the Lunati cam?

Here you go:

Vehicle Make BB Chrysler, Chrysler Camshaft
Type Hydraulic Roller
RPM Range 2200 to 6200
Intake Lift 0.535 Exhaust Lift 0.550
Intake Duration at 50 231 Exhaust Duration at 50 239
Advertised Intake Duration 282Advertised Exhaust Duration 290
Camshaft Series Voodoo
Valve Setting Hydraulic
Lobe Separation Angle 110