Figured I would throw this out there....A while back I posted about a fully forged 383 short block I have ..Eagle crank,srp pistons, O ringed, internally balanced, etc,etc....

With pro comp heads 190 cc 64 2:02 1:60 with a lunati cam 60103 489/504-which will be higher since I'm using 1.6 roller rockers,how much horsepower you figure?

2-1/2 inch hooker super comp headers ,750 carb,rpm dual plane manifold.....4 spd car..

Presently running a 3:70 set up which I'm thinking of going back to a 3:36.........Whines a little too much on highway for me.......3:70 is a great great street gear.......Not great for long highway rides...

 

350 RWHP...which is a total guess. I am not a professional HP estimator. Just a guy with a keyboard.

 

I just finished and dyno'd mine ~Same RPM manifold, 780Quickfuel, 200 Dart heads, speed pro hypereutectic pistons, comp cam 286.
458 hp 455 torque.

 

Nice numbers, very nice.....

 

Post the air flow at 0.200" -0.500" lift for your Patriot heads and the advertised duration of the cam and the 0.050" duration and I'll plug it into Desktop Dyno for you...


Adam

 

For the headers, I assume you mean the Hooker Super Comps with 1 3/4" primaries dumping into 2 1/2" dual, full-length exhaust with mufflers?

(If so, and your HP estimate is in the 350-400hp range, you'd probably be better off with the 1 5/8" diameter Hooker Comps to keep the low to mid-range torque up as you're going to gain nothing / very little/ lose a little in the way of upper-range HP by stepping up to a 1 3/4" primary with 350-400hp.)

Adam

 

I used these airflow #s at 28" H20:
INT EX
.1-71 55
.2-127 104
.3-178 132
.4-222 165
.5-253 180
.6-279 181
.7-287 182

And the cam specs from: http://www.lunatipower.com/CamSpecCa...rtNumber=60103 (assume installed straight up)

I don't know what your static CR is, but I plugged in 9.7:1.

Converting your valve lift to 1.6RRs = 0.522" intake; 0.538" exhaust


With the seat-to-seat degrees entered for the cam DesktopDyno spits out: 379 HP @ 5,500 RPM and 424 ft lbs @ 4,000 RPM.

You should definitely use the 1 5/8" non-comp Hooker headers.

If you use the 0.015" super thin Felpro gasket, your CR improves to 10.2:1 and I get: 388 HP @ 5,500 & 431 ft lbs @ 4,000 RPM.


If I switch to using the 0.050" cam timing (and keep the 10.2:1 CR), I get: 400 HP @ 5,500 & 417 ft lbs @ 4,500. -I've heard some people on here before state that they feel that DDyno is more accurate with seat-to-seat cam timing, but I have no idea; somewhere in the range is reasonable.

Either way, 1 5/8 primaries seem like a better idea.

Adam

 

Random but interesting: Same combo but with a retrofit roller cam DesktopDyno says 423 HP @ 5,000 and 480 ft lbs @ 4,000 RPM. (is 23 HP and 60 ft lbs worth $1,000- probably not and the torque increase seems pretty shockingly high...)


Adam

 

I'm a novice at this but I don't think your combo of head and cam works.

My reasoning is this. A good target dynamic compression ratio is 8.1 to 8.5. Your static compression ratio can be MUCH higher than this as long as your intake valves close sufficiently late to reduce the higher static compression ratio to a reasonable DR.

However, with your gear, I calculate:

Static compression ratio with relatively bad .06 quench = 10.58
.04 gasket, .02 deck height
5cc valve relief (SRP flat tops?)
64cc compression chamber

Dynamic ratio = 9.8
using Lunati 60103 with intake closing 39.5 ABDC

Assuming a better quench with a 0 decked block with .04 gasket, your SR raises to 11.1 and DR raises to 10.3:1.

As I mentioned, I'm a novice at this but this combo of small combustion chamber, early closing cam and bad quench looks like "boom" to me.

 

Oh man,that is quite a bit of info you have there...Thanks so much.....The headers are 1 3/4 going into 2 -1/2 exhaust w 40 series flowmasters..

All I mentioned above is on my 350 .40 over in my car now.......I was just thinking of switching everything over to the 383 block....

Great info Adam,thanks for taking the time..

 

Just to be clear: All the #'s were as a 383; not a 350....

Adam

 

Yea, I forgot that my estimates were based upon the stock L82 block and a deck height of 0.025"; obviously if he goes with a 383 rotating assembly his CR will change depending upon the piston he goes with.

Good advice to figure out your static CR and ensure that your cam is big enough to keep your DCR in the safe zone:

I was using the Jeep calculator and using these values for my L82 stock bottom end and the Felpro thin gasket:
Cylinders: 8
Bore: 4
Stroke: 3.48
Combustion Chamber: 64cc
Deck clearance: 0.025 inches
Gasket Thickness: 0.015"
Gasket Bore 4.1" (no idea where this comes from; I guess the Felpro gasket stats)
Valve Relief: 5cc (looked this up for L82)
piston ring height: unknown-left blank
Piston to Bore clearance: unknown-left blank
Altitude: I'm at like 15 feet lol so "0"
Connecting Rod: 5.7"

And got 10.2:1 static.

https://www.jeepstrokers.com/forum/calculator/


Adam

 

Even with a 10.26 SCR using a 350 that Lunati cam still doesn't work because the DCR would still be 9.5:1.

That cam needs a SCR of around 9.1:1 to end up with a DCR of 8.5. Or, to deal with the small combustion chamber you need a cam with IVC greater than around 63 degrees.

 

The cam is going into the 383 block,that's if I decide to use it.......I know you have heard this before but, its going to be a budget build.....The 350 I have in there now runs very very strong....Thing is,it started burning oil last season.......Its burning through the rings.......Car still is very healthy and has a nice choppy idle with that cam......Power comes on right away and all the way through to 5,500 rpm....

If you think that cam is not the best choice for the 383,what do you recommend? Its not going to be a track car.....Looking for light to light power...

Peace....

 

def do the 383, you wont regret it. 40 lbs, 60 etc. You better believe youll feel it. Less throttle, more go.

 

I think you'll be fine. If you decide to do the swap, just do the measurements for quench etc. and figure out what your compression actually is. The gasket thickness - compressed - on a std Fel-Pro is around 0.039" so that changes the numbers guesstimated above a bit. With aluminum you can get away with quite a bit more compression as well.

The numbers on the Comp 286 are really nice, but lots more duration than you have with the Lunati. I ran a similar Ultradyne some years back with 231/239@50 and got 384hp and 425lbft with a 9.5:1 383. It was almost a bit much for the street off idle, so I think you'd be really happy with that Lunati and it should pull stumps off idle, especially with a dual plane.

The only way to know the real number is dyno it, and I think a 1/2 day on the dyno is worth every dollar for the tune and timing. Good luck!!

 

I think you're doing something wrong with your calculation for 3 reasons:
1. people run cams this small and even smaller with 350s with this type of static CR all the time; it has a larger intake duration than the stock L82 cam (227 vs the L82 cam's 222) with only a 0.5 point increase in static CR and the op is using aluminum vs. iron heads
2. I'm running a near identical cam intake duration @ 0.050" (228) with a nearly identical static CR and my DCR isn't anywhere near your # (although mines a fast acceleration roller cam so the advertised/seat-to-seat duration of my cam might be less than the Lunati cam)
3. I just calculated the DCR using the Jeep calculator and didn't end up with anywhere near a DCR of 9.5:1 (you're probably using the duration @ 0.050" instead of the advertised / seat-to-seat duration)

I just plugged all the #s into the Jeepsite as a 4.040" bore; the 40 thousandths over ups the static CR from 10.2 to 10.45 static CR and makes the dynamic compression ratio 8.39 and the quench 0.040" (about what it should be).


-Are you using the cam's duration @ 0.050" instead of the advertised duration?? (I just did that and I get a dynamic compression ratio of 9.5.) -Most of the DCR calculators require you to enter the ADVERTISED duration / seat-to-seat duration, not the 0.050" lift- the actual intake close event is only directly related to the seat-to-seat duration; not the 0.050" duration because the tool would have to make a guess about the velocity of the cam intake lobe ramp to estimate the intake close event, rather than actually calculate it.



Adam

 

Copy the gmpp zz383 specs and you’ll be at 450hp+

 

Spend a day or two in an engine building shop and you'll notice hardly any modern engines have any "quench" because quench doesn't accomplish diddly-squat. The HEMI's have ZERO quench and most of the other engines have little to no quench. Many years ago it was assumed a tight quench added more power but that thinking was abandoned long ago when everyone began to realize the key to more power was stuffing more air into the cylinders by tilting the valves toward their ports. That's why the big block Chevrolet and Fords came out with canted valves which then became REALLY canted like those in the HEMI's.

 

DCR doesn't involve intake duration, only IVC degrees ABDC. No DCR calculator should be asking what the duration is. This cam has an IVC of 39.5. This early of an IVC means the DCR will be a very high percentage of the SCR. My take on this cam is that it was designed for a low compression engine with good emissions, low end torque and a wide power band.

However, maybe I am reading it wrong. Here is the cam spec sheet I used: