I've seen A LOT of posts about making HP with a 318-So why is it so ???

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My 68 Valiant came with a 380hp crate 360 and 2.96 gears an a 2800 stall on 245 tires.
It's pretty soft under 2000 rpm, in town under 40 mph have to drive in 2nd or it lugs it still gets up and goes but the 2.96 are definitely holding it back. Need to get it up to 40 mph in 1st then give it before I get any real sense of the power it's got.
 
273 said:
My 68 Valiant came with a 380hp crate 360 and 2.96 gears an a 2800 stall on 245 tires.
It's pretty soft under 2000 rpm, in town under 40 mph have to drive in 2nd or it lugs it still gets up and goes but the 2.96 are definitely holding it back. Need to get it up to 40 mph in 1st then give it before I get any real sense of the power it's got.
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A 3.55 would wake it up pretty good.
 
toolmanmike said:
A 3.55 would wake it up pretty good.
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It would and I may go with them or even deeper, I don't drive on the highway much. For Now I'm keeping the 2.96 plan on swapping a dual plane and a 262HR-12 cam or similar got most of the lift my cam has but lot less duration and wider lobe separation, then I'll decide what gear if any I want.
 
RustyRatRod said:
There's a warmed up 56 331 Hemi five feet away from it. I've thought about it. Here's the plan. The 170 and three speed comes out. 170 on the stand to get a Weber 32/36 and bored out exhaust manifold and a basic valve job and a new timing set and the whole thing gets resealed.

While it's out, the 400 gets mocked up with heads and exhaust manifolds and lowered in place "to see" how bad "it won't fit". Lots of pictures taken. Then when I figure out if the three on the tree can stay, the slant goes back in with 2 1/2" upgraded exhaust all resealed up with new timing set and a snappy little Weber. Even if I leave the 170 in at that point (and it's very likely I will) I will have new information for those want to big block swap an early A body. And if for some reason I decide to big block the car, I'll go ahead and hang the Ford 9" under the car and do it. I might. You never know. I also still have my long rod 225 build going on too, so "there's THAT". lol
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How about a 8" Grabber rear end with 4.62 gears and a mini-spool?? :)
 
Good question. (1/4 ET) I think a good and fair guess is excellent inputs into a computer calculator. Try the Wallace stuff. It does assume the car is hooking and booking.

3.23 & A 26 tire would be good. I’m also not fond of anything higher than 3.55’s for an actual everyday driven street car. My ‘79 Magnum has 3.55’s & a 245/60/15 which is about 26-1/2 or so. No cam in the 5.9 power plant though. It’s just a few RPMs higher than the 3.23’s it replaced. The bearing for the pinion let loose on the 9-1/4. BOOM @ 65 & lots of smoke in the mirror! LMAO!

I had 3.23’s and what ever the stock tire was for a ‘73 Cuda w/14” wheels was. They were small tires at IIRC, 225/60/14. I forget. Tiny suckers looking like a doughnut to eat. It did tach rather high for the Hwy. I thought.
 
Bighead440 said:
How about a 8" Grabber rear end with 4.62 gears and a mini-spool?? :)
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In the Duster
(Lord oh mighty help me get there again soon!)
I have 4.88’s. Tire size to be determined later. Unless I put half a Big Foot tire under it, it’s gonna rpm high on the side streets.

My son-in-law and I had a B-400 727 combo we just beat the Baaaaa-Juesus out of light to light locally having a scream doing it handing out a few pastings in the short light to light area.
 
Wyrmrider said:
do you own that white box cam yet
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Who has one to measure?

Late to the Desktop dyno party, but a couple observation using the Dynomation version.
@stixx, @PRH and @toolmanmike.
If you recall we compared a 340 build to some of the magazine 340 dyno tests.
The only way to get the program to show a curve that looked like and peaked at the same rpm as the real dynos runs was by estimating the actual .006 using the .004.
upload_2020-6-9_19-22-56.png


Compared with for example Hot Rod's Test at Edelbrock in '69 or some of the more recent ones.
Edelbrock LD4B

A couple things I've noticed with Dynomation and I assume desktop dyno.
The fill empty method makes big jumps in the curve when the hi-po intakes are selected, bigger carb, etc.
Putting in actual head flow numbers helps get a little more realistic results sometimes.
I started to fiddle around with the rod ratio (use a chevy with same cam for example) to see if the program took into consideration dwell time - didn't seem to.
To use the wave-flow model, one really needs to have a bunch of measurements including the port volumes. Good for learning the effects but otherwise GiGo.

Between 2010 and 2014 @CPDave and I ran various sims on both Dynomation and Pipemax. I recall he thought they came fairly close and pipemax was was useful in predecting the effect of changes to the exhaust. I don' have any handy graphics for the Zebradart 318 ot post 'em.
 
PRH said:
My 30% is from you posting the TQ would go from 340 to 450.
That’s a 32% increase........ and my response was...... where is it coming from....... since I have never seen that.

Don’t take this the wrong way(and I realize you didn’t write the program), but...... 464ft/lbs@2000 from a 318?
Thats gonna get a firm “NFW” from me.
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I agree. That program was written to sell aftermarket camshafts.
 
post 199
too tall a gear rumble?

post 205
I’m also not fond of anything higher than 3.55’s
higher numerically or higher /taller ratio

mattax
mopar advertised are closer to .008
 
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One thing on here I don't see recommended much it 2.74 1st gear. I know gives a wide ratio drop and not be the best for some drag applications.
But on the street I think it would be a good thing ? Since were mostly dealing with 3.23-3.55 gears and mostly under 50 mph full throttle runs 1st and maybe a bit of 2nd gear.

I see 2.74 1.45 1 with 3.55 gears as like a 2 speed powerglide, deep gears with an OD if one existed.

1st 2.45 x 3.91 = 9.58

1st 2.74 x 3.55 = 9.72, 2nd 1.45 x 3.55 = 5.15 and 3rd 3.55

powerglide OD

1st 1.82 x 5.34 = 9.72, 2nd 5.34 and OD .66 x 5.34 = 3.55.
 
i have a built 904 with the low 1st and second gears on standby.Plan was to put it in my dart and go with 2.94's First and second gears would be the equivalent to a standard trans with 3.30 rear gearIf i leave the 3.23 in it will act like 3.60 rear through the first 2 gears.
...2nd to 3rd is not a huge drop especially with a short duration cam having lots of lower rpm torque.
Such a great idea... don't know why it isn't more common?
 
@lkopaska built a lock up 904 with the low first gear for his notchback. It gets good mileage and is spunky with his Commando 273.
 
Wyrmrider said:
mattax
mopar advertised are closer to .008
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Right!
But the program needs a seat to seat based on .006 (ie like Comp cams uses)
So what we did is use the .004 at the valve (1.5 rockers) that you had info on, maybe from an Elgin catalog?
See this post 340 cam specs? and posts 11 and some following.
Using the mopar numbers, or any .008 duration for seat to seat shifted the power curve down and into the lower rpms. Also showed a fast drop off in power after peak.
Using the .004 duration, the program predicted a power curve more in line with what it should be.
So using .004 is the best we can do with DD and Dynomation go until we get some .006 measurements from some real Chrysler cams.

This Dynomation version can't properly handle asymetric lobes. At least not with regular basic inputs. We'ld have to feed in a cam doctor file to see how it would reinterpret that. Since there is a new version that came out 2 years ago, could ask Larry Atherton or maybe on Speedtalk if the new version's cam manager handles the asymetric lobes.

The fact we were able to bring the curve shape and HP peak into the ballpark is a major improvement. At least now we can run simulations and have some degree of confidence of the baseline simulation (factory 340).
 
To PRH's point, look how much that change in seat to seat affected the predicted torque.
upload_2020-6-10_18-43-59.png

The model used for the above is Fill and Empty simulation.
Sea level. Air Temp 68* F, RH 0%
340 std bore, 10:1 CR, 77 cc chambers, Open Wedge Head, Flow numbers X heads posted by Shady Dell
Carb flow 660 cfm, Dual Plane Std flow intake, H.P. Manifolds with Mufflers.

upload_2020-6-10_18-49-38.png


upload_2020-6-10_19-8-4.png

Compared with HR, Mopar Muscle's baseline is very similar. The power gains from the add-ons (carb swap and intake swap) show more gains..read into that what you will. Neither article mentioned what rate of acceleration was used.

The problem with building 318 simulation is similar. We need a good baseline sim to really get a sense of what various changes might do.
 
So how much horsepower is my low comp 318 that ran 11.70s in a 3250 car?, i plan on building more of them, i just bought 2 more cores.
 
273 said:
One thing on here I don't see recommended much it 2.74 1st gear. I know gives a wide ratio drop and not be the best for some drag applications.
But on the street I think it would be a good thing ? Since were mostly dealing with 3.23-3.55 gears and mostly under 50 mph full throttle runs 1st and maybe a bit of 2nd gear.

I see 2.74 1.45 1 with 3.55 gears as like a 2 speed powerglide, deep gears with an OD if one existed.

1st 2.45 x 3.91 = 9.58

1st 2.74 x 3.55 = 9.72, 2nd 1.45 x 3.55 = 5.15 and 3rd 3.55

powerglide OD

1st 1.82 x 5.34 = 9.72, 2nd 5.34 and OD .66 x 5.34 = 3.55.
Click to expand...

I have a lockup 904 with the 2.74 first ready to go behind my 318 poly for my Satellite. I have 2.94 rear gear. Wanted to mention that second gear is 1.54 on the wide ratio 904. Doesn't change much. From the 727 previously in there, gives me a launch like having a 3.28 or 3.23 is closest and still have the cruise rpm of the 2.94 with the benefit of the lockup on top. Win win in my books.
 
ValiantRacing said:
So how much horsepower is my low comp 318 that ran 11.70s in a 3250 car?, i plan on building more of them, i just bought 2 more cores.
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The moroso chart shows about 355hp based on ET.
Speed is a better indicator for power, but you didn’t say what that was.
For a typical bracket type car, unless there is something pretty far off on the combo....... the car should run within 10% of the dyno numbers.
So, if you were in the 90% efficiency range......about 395 STP corrected hp to go 11.70@3250lbs.

If the car is really good, the numbers will show better than 90% efficiency.
And if the car is really really good...... it can actually run better than what the moroso chart predicts.

Even in pretty mediocre air my friends Stocker shows better than 100% efficiency.
 
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