11.3cr 360ci on engine-stand

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BigBlockMopar

BigBlockMopar

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Here are some pics and info about the 360ci engine I recently put together and put on my test-stand for camshaft break-in and checking for leaks or other issues.

The engine will a replacement for the stockish 318ci in my daily driven propane-powered '73 Dodge Dart.
The 318 has a wimpy 8.6:1 compression ratio. Not bad for put-putting around and while I managed to get some decent power out of it with a MegaSquirt ECU controlling timing, it's still no tyre-frier.
Goal with the freshly build 360 is to increase torque, efficiency and hopefully as a result, fuel-economy as well, as the current setup only gets me 10-12mpg.

The 360 had been run shortly before I bought it, but a scored bearing & crank issue made it seize up for the previous owner.
I rebuilt the engine with new bearings, new cam and located a freshly located .010" crankshaft.

Engine specs:
– 360ci +0.030″ overbore.
– Stock rotating assembly except for .030″ KB zero-deck pistons. Fully balanced.
– Iron heads, ‘302’ casting (closed chamber). milled to get 60-61cc chambers.
– Valves have been backcut and polished.
– Smoothed/polished Edelbrock Performer intake, w/ blocked heatriser ports.
- Gasketmatching.
– Tight piston-to-head quench-clearance of 0.025-0.030″.
– Intended rpm-range: 600-3000rpm. Max. rpm around 5000-6000 rpm.
– Fuel is Propane/LPG (±104 octane).
– CompCams Extreme Energy XE256H, used with 1.6 ratio rockers.

During the build I found the KB-piston ring gaps where too tight, so I corrected them to 0.025".
Did a number of other mods on the engine like;
- backcutting and polishing the valves,
- enlarging oil passages in the block,
- modify truck oilpickup to center-pan pickup,
- welded oilcontrol baffle in oilpan,
- modified/installed windage tray from other 360 engine.
- improved oil-transition channel between rear main-cap and oilpump.
- milled heads to 60cc head chamber.

The Mopar '302' heads are the Mopar '302'-casting swirl-port heads.
I gasketmatched and smoothed the runners and polished the chambers, along with some minor contouring of the swirl area.

The camshaft is a CompCams XE256H.
256° In / 268° Ex Adv. dur.
212° In / 218° Ex dur. @ .050"
With 1.6 rockers this will give resp. .4768/.4848" lift.
Lob.sep 110 - ICL 106
With the 11.3cr, this will give a DCR of 8.6:1.

Cam-card;
XE256H-CamCard.jpg


KB-DCR calculator;
DCR-LeftHead.jpg


IMG_4050-1.jpg


IMG_4398.jpg


IMG_4255.jpg



To break-in the new cam I decided to built an engine-stand as well. Something I wanted to do a long time ago already, but it finally happened.
At the day of the engine's first start-up, I bought 5 gallon of 102 octane pumpgas to prevent any form of detonation.
In the car the engine will run on propane only.

IMG_6038crop.jpg


IMG_6026.jpg


The engine break-in went fairly smoothly, aside from the engine getting hot, and (probably because) one lifter failing to pump up.
So I had to stop and go ahead with the break-in after a short cool down period.

After running the engine with a different carb and distributor with quicker timing curve the engine ran pretty cool.
 
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The blue one on the right is my 65 300 convertible
The black on the left is my 62 NewYorker wagon. Above that on the lift is a 60 NewYorker.

Got some more on my site.
 
Nice build that will be a massive improvement in torque over what you previously experienced. My only cautions would be not to turn that engine above 5600 rpm with that super tight quench. I hope your ring gap is a typo and is actually .025" and not .0025" . Sounds good though and should be a tire fryer. J.Rob
 
BigBlockMopar said:
Here are some pics and info about the 360ci engine I recently put together and put on my test-stand for camshaft break-in and checking for leaks or other issues.

The engine will a replacement for the stockish 318ci in my daily driven propane-powered '73 Dodge Dart.
The 318 has a wimpy 8.6:1 compression ratio. Not bad for put-putting around and while I managed to get some decent power out of it with a MegaSquirt ECU controlling timing, it's still no tyre-frier.
Goal with the freshly build 360 is to increase torque, efficiency and hopefully as a result, fuel-economy as well, as the current setup only gets me 10-12mpg.

The 360 had been run shortly before I bought it, but a scored bearing & crank issue made it seize up for the previous owner.
I rebuilt the engine with new bearings, new cam and located a freshly located .010" crankshaft.

Engine specs:
– 360ci +0.030″ overbore.
– Stock rotating assembly except for .030″ KB zero-deck pistons. Fully balanced.
– Iron heads, ‘302’ casting (closed chamber). milled to get 60-61cc chambers.
– Valves have been backcut and polished.
– Smoothed/polished Edelbrock Performer intake, w/ blocked heatriser ports.
- Gasketmatching.
– Tight piston-to-head quench-clearance of 0.025-0.030″.
– Intended rpm-range: 600-3000rpm. Max. rpm around 5000-6000 rpm.
– Fuel is Propane/LPG (±104 octane).
– CompCams Extreme Energy XE256H, used with 1.6 ratio rockers.

During the build I found the KB-piston ring gaps where too tight, so I corrected them to .0025".
Did a number of other mods on the engine like;
- backcutting and polishing the valves,
- enlarging oil passages in the block,
- modify truck oilpickup to center-pan pickup,
- welded oilcontrol baffle in oilpan,
- modified/installed windage tray from other 360 engine.
- improved oil-transition channel between rear main-cap and oilpump.
- milled heads to 60cc head chamber.

The Mopar '302' heads are the Mopar '302'-casting swirl-port heads.
I gasketmatched and smoothed the runners and polished the chambers, along with some minor contouring of the swirl area.

The camshaft is a CompCams XE256H.
256° In / 268° Ex dur. @ .050"
With 1.6 rockers this will give resp. .4768/.4848" lift.
Lob.sep 110 - ICL 106
With the 11.3cr, this will give a DCR of 8.6:1.

Cam-card;
View attachment 1715105038

View attachment 1715105039

View attachment 1715105040

View attachment 1715105041


To break-in the new cam I decided to built an engine-stand as well. Something I wanted to do a long time ago already, but it finally happened.
At the day of the engine's first start-up, I bought 5 gallon of 102 octane pumpgas to prevent any form of detonation.

View attachment 1715105042

View attachment 1715105043

The engine break-in went fairly smoothly, aside from the engine getting hot, and (probably because) one lifter failing to pump up.
So I had to stop and go ahead with the break-in after a short cool down period.

After running the engine with a different carb and distributor with quicker timing curve the engine ran pretty cool.
Click to expand...
Cool, and look at You with Your Somender Singh grooves! Curious what kind of power vs efficiency it delivers....keep the updates comin'..........
 
11.3/8.6 Does not compute!
Installed at 54* ICA,Mr.Wallace says;

Static compression ratio of 11.3:1.
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 9.69:1 .
Your dynamic cranking pressure is 204.60 PSI.
V/P (Volume to Pressure Index) is 189...........................................189! whahoo
How did you come up with 8.6? Maybe a typo?

I don't know anything about propane, but
9.69Dcr and iron heads seems pretty high
And .025 ring-gaps are not gonna work. Another typo?
And .025 squish could mean the kiss of death at 6000rpm. Another typo?
And I sure hope you checked the Piston to Valve clearance
Did I see $1.933 per liter? And how would that compare to US currency, as in how many liters can you buy for an average hours wages?

I can tell you tho, that if it runs 205psi, it will be killer in the torque department. Absolutely killer. It will tend to bust a lotta parts behind it,....... so buy stock in a towing company,lol.
 
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The camshaft is a CompCams XE256H.
256° In / 268° Ex dur. @ .050"
With 1.6 rockers this will give resp. .4768/.4848" lift.
Lob.sep 110 - ICL 106
With the 11.3cr, this will give a DCR of 8.6:1.


Cam card says 212/218 @ .050...................
 
That cam is going to pull hard on a street car, I think you will like it.
 
70aarcuda said:
The camshaft is a CompCams XE256H.
256° In / 268° Ex dur. @ .050"
With 1.6 rockers this will give resp. .4768/.4848" lift.
Lob.sep 110 - ICL 106
With the 11.3cr, this will give a DCR of 8.6:1.
Cam card says 212/218 @ .050...................
Click to expand...
You almost had me there!
It can't be both 256 @.050 AND also [email protected],

The cam card clearly says; duration at .006 is 256degrees
and then elsewhere it clearly shows 54* as the ICA @.006
Did I missread that?
 
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Per the OP:
"– Fuel is Propane/LPG (±104 octane)."

Makes a difference on the DCR that can be used. I am assuming that the 102 Research Octane is just for light load/break-in/initial tuning.
 
As correctly noted, there are indeed some typos in the first post.
I’ll correct them later, typing on a mobile phone now.
 
Just edited the first post with cam-duration and piston ringgap.
Also added a screenshot of the DCR-calculator as found on the KB-silvolite website.

I'll try to take cranking compression pressure reading tomorrow and post the results.
 
There's your problem
That calculator adds 15* to your ICA at .050
If you entered 54* then it will add 15 to it and get 69*
Then indeed the numbers come to
Static compression ratio of 11.3:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 8.65:1 .
Your dynamic cranking pressure is 176.89 PSI.
V/P (Volume to Pressure Index) is 144

But you don't have an ICA of 69*! So this is all wrong.
An ICA of 69* would come on a very much bigger cam;the math says about a 286/110, which is over 4 sizes bigger than your 256.
So, I repeat
it does not compute

I'm not saying you can't run 205psi on propane cuz I just don't know. But if you are operating under the guise that a Dcr of 8.65 is OK and then you are really operating at 9.69 and stuff blows up, I guess then you'll be back to tell us what doesn't work.
I just wanted to point out the error before it blows up....
 
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AJ, I'm now seeing the screwup in the DCR-calculations. Thanks for pointing out.
The KB-DCR calculator seems confusing in that it wants to know the Intake Closing Point at .050. That info is indeed not what's shown on the camcard.
If I just enter '54' as ICP (at Adv.Dur), then the KB-calculator comes up pretty much to the same 9.6 DCR as the Wallache calculator does.
(I actually entered this 54 number in the KB calculator in the very beginning I started looking at this cam, and indeed got the 9.6 DCR. But later I got thrown off by the 'add 15 degrees' line and started using '69' as the number entered.
 
OK great so I guess now We're on the same page.
So Is the new,larger, Dcr gonna work for you?
Like I said I know nothing about propane.
But I have had experience with 200psi,and aluminum heads,and gas, and it is incredible!
Even 185psi is exceptionally sharp and strong. If I didn't have to, I'd never run less. I run .035 Squish,or a tad less, and I haven't had problems in 80,000 miles, with many,many trips into the 7000s.
 
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Propane has about 101-104 octane, depending on its composition and as long as the intake is kept cool enough.
Heat will play havoc with its octane rating.
Only time will tell.

On the engine-stand I haven't been able to let the engine 'work', so that's one thing I don't know yet how it will do under load.
 
BigBlockMopar said:
Propane has about 101-104 octane, depending on its composition and as long as the intake is kept cool enough.
Heat will play havoc with its octane rating.
Only time will tell.

On the engine-stand I haven't been able to let the engine 'work', so that's one thing I don't know yet how it will do under load.
Click to expand...


So I have to ask....why propane? My experience with propane was back in 1984-85 when I had to drive, service and fill them. They were gutless.

Of course, everything was gutless back then.
 
Why propane is for one simple reason; It costs more than half of what regular gasoline costs overhere.

Propane got a bad rep. because in most/all cases it was installed on an engine build/tuned for gasoline, and in most cases the propane carb is mounted 'on top' of the stock gasoline carb.
During the late '70s & '80s pretty much all factory engines where fairly gutless compared to their size. Not to mention tiny cams in combination with low compression ratios, not much was left on the table for the engine to make power with. Switch to propane while not optimizing the engine for the new fuel and you end up with a gutless lump of iron under the hood.

If you tailor the ignition advance curve to propane (in short; more low ignition, quicker advance, less total) a good amount of the lost drivability returns already.
Then comes attention needed to keep the engine as cool as possible, or mainly the intake that is. So closing up the heatriser port is a first thing to do. Installing an open/air gap intake wil help even more.
You really don't want the waterport on a smallblock intake to heat up the intake (unevenly). Big blocks have an advance here already.
Bring up the compression ratio to pre '70s times and you're getting close to gasoline performance again.

But propane really shines at daily, year-round driving.
Especially during winter, a propane engine will start and idle without issues unlike a gasoline engine, that needs help of a choke and fast idle to keep it from stalling. Propane has no liquid particles or droplets to fall out of suspension like gasoline has which cold temperatures and manifolds.
It only needs some engine heat taken from the cooling system to be able to convert the highpressure liquid propane in the tank to a vapour.
 
yellow rose said:
So I have to ask....why propane? My experience with propane was back in 1984-85 when I had to drive, service and fill them. They were gutless.

Of course, everything was gutless back then.
Click to expand...
Probably BECAUSE it was put in standard 8:1 SCR engines. Looks like the OP said the same thing above. Lots of info out there on running propane and the higher CR's used.
 
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