Guess The Horsepower/Torque

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12many

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My son has been asking what I thought the horsepower of this 360 we’ve built would be. I’ve made my guess, but to be honest I may be underestimating things. I told him I would consult with the forum here and see what some of the more knowledgeable think.

1978 360 block (.030” over, not decked)
Speed Pro H116CP pistons w/Felpro 8553 gaskets, calculated approx. 9.75 to slightly higher?)
Speedmaster Aluminum Heads 170cc/65cc
2.02”/1.60” valves (OOTB valve job, Not ported)
Factory 1.5 rockers
Summit (Crane Energizer) hydraulic 272°/216°@ .050”/.454”/110LSA (102ICL)
Weiand Action + DP. Ported : Plenum, runners etc
Street Demon 625
OEM Mopar electronic ignition w/FBO plate and one light spring (replacing heaviest spring)
Patriot 1-5/8” headers (same specs as Dougs)
I’m thinking ballpark 300-325 horsepower.
What say you?


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Factory SM valve job? If so, I believe you're in the right neighborhood. With a good valve job, I would guess "somewhere" around 350. Nice build, though!
 
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Before your last line, I was thinking about 360 hp, but I think you are probably closer.
(By the way, love the wheel/tire combo. Mirada?)
78 Magnum w/904, Hughes 2500 stall, 3.21 rear
 
From the head flow chart, some work by PRH. Not bad numbers out of the box, my throwaway 475A heads are going to be close to that with 1.94/1.60 11/32 stem valves and a good valve job. And I'm more than happy to get those numbers for the final investment cost. Of course, more power is just a cam swap away, given enough cam and converter to match.
SM Head...... ootb vs reworked valve seats(with very small back cut on both valves) and minor bowl blend......

4.00 bore, 28” test pressure, no tube on exhaust.

A-ootb
B-reworked

Intake-
Lift———A/B
.100— 61/65
.200— 120/126
.300— 177/180
.400— 221/230
.450— 231/246
.500— 240/256
.550— 250/267
.600— 250/262
.650— 251/261
.700— 253/261

Exhaust-
Lift———A/B
.100— 49/50
.200— 97/101
.300— 134/139
.400— 154/169
.450— 160/174
.500— 164/178
.550— 166/179
.600— 168/180
.650— 168/181
.700— 168/182

It’s a decent gain considering it’s maybe a 1cc increase in runner volume.
 
yes. It was a great cam for that engine.
Will be interesting to see how it does in this setup, big heavy car, the converter/gearing. Searched a bit, it’s seems often mentioned in 318 builds here, i found some YouTube videos of a guy that used it in a couple of 360 builds (one very similar to ours turns out) and there is a 408 build mentioned here recently.



Very similar specs:

 
The CR is going to save that combo.

The one that got tested here with ootb SM heads had dished pistons that were way down the hole(we didn’t build it).

RPM intake, xe268 cam(too big for the CR), headers, I think it had an Ede 750 on it.
Made 367tq/331hp

I think yours will be closer to 1hp/ci
 
should make around 1hp/ci

slightly larger cam and less head gets in that range.
 
360-370hp I would expect. J.Rob
I think yours will be closer to 1hp/ci

I tried my best researching what the CR would be using those pistons, the 8553 gaskets compressed and the SM chamber cc, along with the 360 block uncut. I’ve seen mention of 10, 9.89 with similar specs, but 9.75 is just my so called educated guess, erring on the conservative side. It could be slightly higher, opinions?
 
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