I've seen A LOT of posts about making HP with a 318-So why is it so ???
- Thread starter RAMM
- Start date
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PRH
Well-Known Member
For grins, try this:
360+ .030
8:1cr
XE268 cam
Performer rpm
Ede 750
1-3/4 headers
Ootb SM heads(flow numbers are in with the head flow stuff)
See what it spits out.
360+ .030
8:1cr
XE268 cam
Performer rpm
Ede 750
1-3/4 headers
Ootb SM heads(flow numbers are in with the head flow stuff)
See what it spits out.
PRH
Well-Known Member
Ootb Speedmaster aluminum.
2.02/1.60, flow numbers are in with the flow data sticky
2.02/1.60, flow numbers are in with the flow data sticky
Sorry, got most of the info.
PRH
Well-Known Member
It’s all right there, no?
Looks like 365 horse @ 4500 and 488 lb/ft @ 2500. A bigger cam would give you more horse but less torque I bet.
PRH
Well-Known Member
So, this is an example of a Desktop Dyno vs the real dyno......
PRH
Well-Known Member
Not even looking at the values........ the two results show a 2000rpm discrepancy in where the tq peak occurs.
The real world result on the TQ increase for this build was......just about 2% based off the factory gross rating of 360ft/lbs.
The bigger heads and cam, 4bbl carb and headers moved the tq peak up 2100rpm(2400 up to 4500), and that results in the gain of 76hp.
Wanna try a 440 6bbl?
The real world result on the TQ increase for this build was......just about 2% based off the factory gross rating of 360ft/lbs.
The bigger heads and cam, 4bbl carb and headers moved the tq peak up 2100rpm(2400 up to 4500), and that results in the gain of 76hp.
Wanna try a 440 6bbl?
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PRH
Well-Known Member
I bought a desktop dyno about 20 years ago.
I was doing a lot of dyno testing back then, and already had a pile of dyno sheets to compare with.
If you modeled something like a SBC 383 with high CR, a big roller cam, nice intake, headers, carb, good heads....... you could end up with the numbers somewhat close-ish.
But any kind of BB Mopar with std port heads and a big cam....... the numbers were way off.
On my old version, the real numbers were usually quite a bit better than the DD numbers for the std port bracket race type 440.
I had modeled two motors that were going on the dyno, just to see what it spit out for numbers.
A 446 and a 493.
Both street/strip builds with RPM heads.
Both got very similar solid cams, same intake, carb size, same CR, etc.
The DD was showing the 493 would make about 40-45hp less than the 446.
On the real dyno, the 493 made about 30-35hp more than the 446.
One of my customers has DD, along with two other, quite a bit more expensive engine sims, that have way more intricate inputs....... and they’re not all that close on many builds either.
I was doing a lot of dyno testing back then, and already had a pile of dyno sheets to compare with.
If you modeled something like a SBC 383 with high CR, a big roller cam, nice intake, headers, carb, good heads....... you could end up with the numbers somewhat close-ish.
But any kind of BB Mopar with std port heads and a big cam....... the numbers were way off.
On my old version, the real numbers were usually quite a bit better than the DD numbers for the std port bracket race type 440.
I had modeled two motors that were going on the dyno, just to see what it spit out for numbers.
A 446 and a 493.
Both street/strip builds with RPM heads.
Both got very similar solid cams, same intake, carb size, same CR, etc.
The DD was showing the 493 would make about 40-45hp less than the 446.
On the real dyno, the 493 made about 30-35hp more than the 446.
One of my customers has DD, along with two other, quite a bit more expensive engine sims, that have way more intricate inputs....... and they’re not all that close on many builds either.
PRH
Well-Known Member
If you use the butt dyno before and after the results are more accurate . lol
I can tell up to 700 HP. lol
PRH
Well-Known Member
Let me know how many head flow data points you need for the 446.
PRH
Well-Known Member
If you need more than this let me know:
446ci
9.5cr
Comp 280 magnum cam
(280/280, 230/230, .480/.480, 110lsa, in at 106)
Stock rockers
Factory style 6bbl carbs & manifold
1-7/8” headers
346 heads with blended bowls and
2.08/1.74 valve sizes
Flow:
Lift—— in/ex
.100— 68/57
.200—141/106
.300—204/141
.400—238/166
.500—249/178
.600—255/186
I’m mostly curious as to what it predicts the TQ to be......and where.
446ci
9.5cr
Comp 280 magnum cam
(280/280, 230/230, .480/.480, 110lsa, in at 106)
Stock rockers
Factory style 6bbl carbs & manifold
1-7/8” headers
346 heads with blended bowls and
2.08/1.74 valve sizes
Flow:
Lift—— in/ex
.100— 68/57
.200—141/106
.300—204/141
.400—238/166
.500—249/178
.600—255/186
I’m mostly curious as to what it predicts the TQ to be......and where.
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I agree that you wouldn't get 450 lbs-ft out of a 318, some 408 don't make much more than that, unless your talking some crazy highly tuned build like a tunnel ram,W2, big solid roller with 15:1 cr 318.
Most regular guy builds with street cams and cr are gonna be between 1.1-1.25 lbs-ft per cid. so 350-400 lbs-ft and most wouldn't see 400 lbs-ft.
Torque mainly depends on a NA engines displacement, VE% and CR. Torque very by a pretty narrow range around 1:1 to 1.45:1 lbs-ft per cid. I'd use 1.15:1 as an general average build estimate.
Most regular guy builds with street cams and cr are gonna be between 1.1-1.25 lbs-ft per cid. so 350-400 lbs-ft and most wouldn't see 400 lbs-ft.
Torque mainly depends on a NA engines displacement, VE% and CR. Torque very by a pretty narrow range around 1:1 to 1.45:1 lbs-ft per cid. I'd use 1.15:1 as an general average build estimate.
I’ve always said, the sim is a good learning tool but not dead on accurate. There is to much play in the program.
I got a dyno sim, if you plug specs from builds you find it's in the ballpark, it's only strength to me is helping to narrow down cam choices and maybe heads to a lesser degree.
I've done several builds for people here with Desktop Dyno who've run real dyno time and found the results were very close. Now, mind you, I had all of the specs including head flow. The more info you input, the more accurate the output.
stixx
Well-Known Member
I have an older copy of Desktop Dyno that I used to play around with years ago...
Just for giggles I plugged in some numbers for a 'standard' 318 with a tiny bit of a cam, 600 carb and lightly cleaned standard heads (flowing 214cfm max according to the program). This is more or less consistent with other engines I simualted that were usually in the ballpark compared with real builds.
This is true. I do not know what very close is and to others, but the sims are not horrible unless your doing something very wacky with it. There getting better but... there really is nothing like an actual well calibrated & maintained dyno. More on this below.
This is what I have said for a long time.
IMO, the best thing these dyno sims will do for YOU, is help teach you what various changes can do. I don’t think there a bad thing. I don’t think there a GREAT thing. I think they can help a good bit.
The best thing I think people will pick up from these dyno sims is how a cam change cam effect an engine output. Narrow or widen the centerline or increase/decrease a Cams duration on one side then both, you can get a idea of what can happen.
I do not know what the latest versions have upgraded, added or where they improved in. But there a run thing to have. I also don’t know what they currently assume of an intake manifold. Can I input individual runner flow numbers? Can it show the reduction in head flow due to the intake manifold. How about between manifolds?
There are limitations to the program. If anyone asks me about one, I’d just say enjoy the sim for what it is and play with it and learn something from it. There are few of them on the market. I don’t know who’s is best or worst. But I’ll just say I’ll never base my claimed power on it. Ether the actual dyno will or the drag strip will.
Because that’s where the fun is!
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