360hp guesses

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Coulda, shoulda, woulda ! I think this build is a nice low compression build, anyone with a stock short block could duplicate for under 2 grand. Most guy's don't have the coin for the long block version all at once.
The aluminum heads are a great financial start to a future potent short block.
 
It was several months ago when the long block and the associated pile of parts arrived........ but I seem to recall there being a mention of “400hp”....... as maybe that was the original goal.

So, at 331hp....... they’re either happy..... or not.
 
PRH said:
I don’t often bother with threads like this, since there are so many variables........ but what the heck.

Rebuilt, new 360 short block brought in.
Oe type pistons way down the hole.
It showed up with some HD “truck” type 318 heads(the ones with the water crossover instead of exhaust crossover, and they use 18mm spark plugs).
Heads were actually already installed on the motor, but the 18mm plugs were a red flag.
After researching the head casting numbers and seeing what they were, we talked them into using something more performance oriented, so they bought some Speedmaster heads.
Heads were checked out for seat run out, guide clearance, spring load, surface flatness...... all good.
8:1-ish CR
Comp XE268 cam
PRW rockers
STD Performer intake
Eddy 750
1-5/8 - 1-7/8 x 3 headers

It’s on the dyno now...........Guesses?
Click to expand...
Were the heads like these and you're saying they ran just fine out of the box?
Speedmaster PCE281.2146: Cast Aluminum Cylinder Head Small Block Mopar 318/340/360 w/Hydraulic Flat Tappet Cam | JEGS
 
The only things that got changed were, two of the springs tested a little low, so they got shimmed up, and the valve seals didn’t fit well on the guides at all, so they got replaced.

Seats were pretty wide, but runout was good...... guide clearance was on the looser end of the range(about .0020-.0025).

Flow: 4.0” bore, 28” pressure:
Lift—— I/E
.300—177/134
.400—221/153
.500—240/164

B46A2C25-9406-4E90-9C48-D638D7C317B8.jpeg


FCF72AD2-24D9-4F87-A3CD-49FCA65E9F38.jpeg


To put the flow in perspective....... bowl ported J head with 2.02 valve that made 90hp more than this motor did(also a pump gas 360).

Lift—— I/E
.300—183/131
.400—221/151
.500—223/158
 
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PRH said:
The only things that got changed were, two of the springs tested a little low, so they got shimmed up, and the valve seals didn’t fit well on the guides at all, so they got replaced.

Seats were pretty wide, but runout was good...... guide clearance was on the looser end of the range(about .0020-.0025).

Flow: 4.0” bore, 28” pressure:
Lift—— I/E
.300—177/134
.400—221/153
.500—240/164

View attachment 1715369435

View attachment 1715369436

To put the flow in perspective....... bowl ported J head with 2.02 valve that made 90hp more than this motor did(also a pump gas 360).

Lift—— I/E
.300—183/131
.400—221/151
.500—223/158
Click to expand...
Thank you for that.. I have a 410 stroker about 5 maybe.010 out of the hole. Flat top with relief. I run open chamber of 596 heads with 202 valves and a mild amount of porting that means I did it for a couple days and paid for a couple hours of shop time to touch them up no flow bench. They did a little gasket matching to the heads to make sure I wouldn't have any clearance issues, very little.
Anyways I've been wanting to try some aluminum heads and they look pretty reasonable on a budget. I would like the weight loss up front and I would hope to get a little bang for my buck. I was thinking in my case and my combination it would work a little more to my advantage then the stock stroke did?
Screenshot_2017-02-26-22-31-00.png
 
I don’t remember what the part number was.
I may have posted it in one of the prior Speedmaster threads.

They were assembled heads with a dual spring for a hyd cam and 10* retainers and locks.

Just because the two I had were good doesn’t mean any other ones are.
IMO they should always be checked out before being put on.
 
PRH said:
I don’t remember what the part number was.
I may have posted it in one of the prior Speedmaster threads.

They were assembled heads with a dual spring for a hyd cam and 10* retainers and locks.

Just because the two I had were good doesn’t mean any other ones are.
IMO they should always be checked out before being put on.
Click to expand...
I agree I don't think I would literally peel them out of the box and slapped them on without pulling things apart and making sure everything works correctly. I guess my question would have been more towards the other end of my questions LOL is there anything to be gained besides weight savings or would there be like in your case losses?
 
I'm trying to sell myself on the fact that I may be able to just use pump gas only with aluminum heads. As it is I have to put 25% 110 race fuel to get it to shut off correctly...
 
I guess my question would have been more towards the other end of my questions LOL is there anything to be gained besides weight savings or would there be like in your case losses?
Click to expand...

Losses? What losses?
The Speedmaster heads weren’t tested against anything else.

Two different builds...... one just a better plan than the other as far as power goes.

With a better valve job and a quick bowl blend, on a 10.5:1 408/416, the right cam(solid), induction, etc....... I don’t see how you couldn’t easily be in the 480hp+ range with those heads on pump gas.

In my mind....... that should be a slam dunk.
 
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PRH said:
Losses? What losses?
The Speedmaster heads weren’t tested against anything else.

Two different builds...... one just a better plan than the other as far as power goes.

With a better valve job and a quick bowl blend, on a 10.5:1 408/416, the right cam(solid), induction, etc....... I don’t see how you couldn’t easily be in the 480hp+ range with those heads on pump gas.

In my mind....... that should be a slam dunk.
Click to expand...
The 596 heads ?
 
It’s drifting way off topic now......

My 383 dynoed at 485hp.
Installed in my 3670lb race weight 68 Satellite it went a best of 11.26@119+ with the flat hood, mechanical fuel pump, and the original 5/16” fuel line and pick-up.

That motor had TRW 2315’s, stock rods, a cast crank from a 400, unported 906’s that flowed 235, a .567 lift solid cam, ootb Performer RPM, and a ported 850 Holley.

The car had been sitting outside on a trailer, under a cover for 6 years when I bolted that motor in...........first pass with the 7 year old bias slicks was an 11.82, next pass was an 11.62.
At that point I was still running the crank driven water pump as well.
The 11.26 was with an electric w/p drive and I had replaced my worn out SS springs with CalTracs and XHD springs.
I was also running radial slicks by then.

I can’t think of any reason why a 408/416 making similar power wouldn’t run just as good.
 
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So, if you built a 408 with the SM heads, valve job and bowl porting, Victor manifold, similar cam as the 383........ it should make at least the same power.
It’s 20ci bigger, the heads will flow at least 20cfm more, and the intake is better.
In the car, the aluminum headed SB is probably 50lbs or so lighter than the iron headed big block.

It should run at least as good.

If it doesn’t make the power, someone missed on the combo.
 
j par said:
I'm trying to sell myself on the fact that I may be able to just use pump gas only with aluminum heads. As it is I have to put 25% 110 race fuel to get it to shut off correctly...
Click to expand...
If you go to close chamber heads, you'll gain enough compression that the aluminum won't matter, you'll still be mixing gas or pulling 10* of timing out ..... just my thought
 
318willrun said:
If you go to close chamber heads, you'll gain enough compression that the aluminum won't matter, you'll still be mixing gas or pulling 10* of timing out ..... just my thought
Click to expand...
I was thinking about as much gasket thickness as I can get...?
 
j par said:
I was thinking about as much gasket thickness as I can get...?
Click to expand...
I don't know what gasket you are using now, but yes, a thicker gasket will help. However, knowing the cc' of the cast heads you are using now vs. the cc of the aluminum heads will tell the real story. Were you 596 heads cut?
 
J par is trying to learn from your engine and apply to his engine?? Kind of, sort of on track...
Click to expand...

Honestly........ if he’s trying to learn something by comparing his high Cr stroker with a tunnel ram to an 8:1 360 with a std Performer on it...... he’s totally lost........ and going deeper and deeper into the woods.

The only similarities between the two motors are they’re both SB Mopars.
 
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PRH said:
Honestly........ if he’s trying to learn something by comparing his high Cr stroker with a tunnel ram to an 8:1 360 with a std Performer on it...... he’s totally lost........ and going deeper and deeper into the woods.

The only similarities between the two motors is they’re both SB Mopars.
Click to expand...
You didn't need THIS thread to know that J par is lost...... :D :D
:rofl:
 
That doesn't sound right, unless your car is really heavy...like 4000 pounds. I think I had you at 430ish.

Now I can't find my P/S calculator.
Click to expand...

Don’t take this the wrong way...... but without good dyno data...... the P/S calculator is somewhat useless.

What is does is show you whats “possible”.
If your car sucks, the numbers are just that........ numbers.

If you don’t know how much power you have, and what the car weighs...... you don’t really know what it “should” go.

I’ve heard the “you don’t race dynos” thing for almost 30 years.
But I can tell you this........ if you don’t make enough power to run the number you want to....... you’re never going to get there.

On the other hand if you need to make 500hp to reach the target, and you make 550hp....... but the P/S calculator shows you’re making 450hp....... you don’t need to waste any money on the motor.
Work on the car.
 
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