[Half-Inch Stud]

Seems wise to ask for posts of NA TQ curves, that indicate the PMD engine's intrinsic POWER production vs rpm.

Instructive to see the flattest TQ curve. Could show a hump due to Exhaust.

No getting away from Engineering, data, and "physics". I want to see the Flat TQ from low RPM thru "drop-off" rpm. The matter here will reveal the ideal LSA. Intake LC, and Exhaust LC, and yea the correct duration for thee most broad rpm.

I want to apply this to a different engine family, for towing, mpg, and of course ET, considering the weight.

[PAUL K]

HIS, not sure if this is what your looking for. I thought this was a pretty stout pump gas build. 462, ported 16 heads, Torker manifold an a tight 105 LSA roller cam.

[Dragncar]

Stout for sure. Plenty of guys have not done that with E head pump gas builds.

[Shiny]

HIS, correct me if wrong, but you're looking for the complete torque curves, essentially asking for the sensitivity of the torque curve to cam LSAs, correct?

If I follow, you're suggesting peak torque may not be your focus, but rather, the most consistent torque across a WIDE range of rpm.

Your reference to towing and mpg suggests you don't want the "best" 1/4-mile solution, but more about normal driving at lower rpm?

This might be difficult to find, given all the model and dyno data (at least posted on this forum) seem to start relatively high and are addressing race performance... but maybe some of the models can predict from say, 1000 rpm to 4500?

How would you define "flat"? What would be your metric?

[Scott Stoneburg]

My 535, pump gas, street/strip combo. I don't have a graph, but here's the numbers

[Half-Inch Stud]

@Paul K well impressive mid TQ but drops across the 5000 rpm range. Bet it runs hard.
@Shiny, well i figure the high&broad TQ allows some fun Highway commute driving.
@ Scott Stoneburg That's it !! Impressive! 4100 thru 6900 rpm looks amazing. What cam?

[Scott Stoneburg]

Originally Posted by Half-Inch Stud

@Paul K well impressive mid TQ but drops across the 5000 rpm range. Bet it runs hard.
@Shiny, well i figure the high&broad TQ allows some fun Highway commute driving.
@ Scott Stoneburg That's it !! Impressive! 4100 thru 6900 rpm looks amazing. What cam?

CamMotion Solid Roller.
276/284@.050
.455/.450 lobe lift
113 LSA

[Half-Inch Stud]

@Paul, Now wondering if your Torker I plenum walls and ceilings are hogged-open-enough. I opened-up a few.
@Scott, when faced with a 0.442" lobe Roller, i punted for fear of the expense to get it together. Someone else is gonna try.

I realize it's not fair to ignore the iron heads vs aluminum CFM, buuuut Could/does the 113 vs 105 LSA explain the large difference (one increasing HP, other decreasing hp) in 5000-6000 results?

Suppose the Pump-Gas Octane needed to run is shared.

[Stan Weiss]

Originally Posted by Scott Stoneburg

My 535, pump gas, street/strip combo. I don't have a graph, but here's the numbers

Scott,
Here you go.

Stan

[Scott Stoneburg]

Originally Posted by Stan Weiss

Scott,
Here you go.

Stan

Cool, thanks Stan.

@HIS... Mine runs on 93.

[steve25]

There's so many factors involved in having a wide and flat as possible torque band that it's hard to discuss, because so many things hing greatly on other factors.

One big factor is the overall Intake tract port air speed.

For example If you have chosen a Cam that for your cid will have a power range of 4500 to 7000, then you want to have a Intake tract who's minimum port area will keep the port air speed in that rpm range to between 350 and maybe 450 fps .

There's a number that can be applied to the Exh side of the motor also but for my example above let's assume where in the ball park of what's needed.
I think it also needs to be keep in mind that once any motor hits its rpm of peak torque then one or more factors that control the overall all flow in and out of that motor have been tapped for all there worth.

[Half-Inch Stud]

Yes, and i was taught that 350 fps is the number to shoot for in CSA and uniform-average port velocity. Corollary being a 400-200 fps spread in a port is a bad deal.

As for reaching a peak TQ, and thats it, yea never seen/remember a double-hump
TQ curve. Wow, that would be a great April fools Tech article.

Inspiration of this thread is the 4.6L Modular engine family has many HP performance variants. WELL, i excel-plotted all the NA 4.6L advertised HP-rpm and to no-surprise the low-mid rpm TQ was within 10ft-lbs of each other (Towncars, Mushstangs, etc), but the TQ-HP nosedive with increased rpm is quite wide and show opportunity to improve with a cam swap. So had to be the cam, not FI,Timing, exhaust pipes. Some in the EXH manifold vs ss-headers.

Think i would have learned something with Pontiac perf, but migrated to 455s about 36 years ago. Probably good on Duration pick, but so ignorant on small engine cam LSA.

[Stan Weiss]

Originally Posted by Scott Stoneburg

Cool, thanks Stan.

@HIS... Mine runs on 93.

Scott,
You are welcome.

Was it dynoed of 93 / pump gas or has it been raced on 93 / pump gas?

If so I would like to add you to the pump gas list.

http://www.magneticlynx.com/carfor/pont_gas.htm

Stan

[Stan Weiss]

Originally Posted by Half-Inch Stud

Yes, and i was taught that 350 fps is the number to shoot for in CSA and uniform-average port velocity. Corollary being a 400-200 fps spread in a port is a bad deal.

As for reaching a peak TQ, and thats it, yea never seen/remember a double-hump
TQ curve. Wow, that would be a great April fools Tech article.

Inspiration of this thread is the 4.6L Modular engine family has many HP performance variants. WELL, i excel-plotted all the NA 4.6L advertised HP-rpm and to no-surprise the low-mid rpm TQ was within 10ft-lbs of each other (Towncars, Mushstangs, etc), but the TQ-HP nosedive with increased rpm is quite wide and show opportunity to improve with a cam swap. So had to be the cam, not FI,Timing, exhaust pipes. Some in the EXH manifold vs ss-headers.

Think i would have learned something with Pontiac perf, but migrated to 455s about 36 years ago. Probably good on Duration pick, but so ignorant on small engine cam LSA.

Mark,
On a flow bench @ 28" of water most people want the average peak air speed to be around 300 fps on the intake. One still needs to pilot probe the port to make sure there are no really high or low localized spots which can cause problem even with the average speed looking good.

Stan

[Scott Stoneburg]

Originally Posted by Stan Weiss

Scott,
You are welcome.

Was it dynoed of 93 / pump gas or has it been raced on 93 / pump gas?

If so I would like to add you to the pump gas list.

http://www.magneticlynx.com/carfor/pont_gas.htm

Stan

It was dyno'd on a 110 because that's what the operators already had in the Dyno tank. I have raced it on 93. But have no good track numbers due to trans breakage and traction issues.

[Skip Fix]

Here is my 500" IA switched to a graph as well as the 470" 409.

[Scott Stoneburg]

Originally Posted by Stan Weiss

Scott,
You are welcome.

Was it dynoed of 93 / pump gas or has it been raced on 93 / pump gas?

If so I would like to add you to the pump gas list.

http://www.magneticlynx.com/carfor/pont_gas.htm

Stan

Stan, I was able to get the time slip from the best run to date. I think it's still got a little more in it, I feel as the 60' is about .1 off due to the purposeful soft leave in an attempt not to blow the tires off.

[AG]

That's about 9.55 in the 1/4. What is your car and what does it weigh?

[Scott Stoneburg]

Originally Posted by AG

That's about 9.55 in the 1/4. What is your car and what does it weigh?

67 Firebird, weighs 3650 with me.

[Half-Inch Stud]

@ Skip Fix, Those TQ curves hold well to 5700 rpm, and the common Builder in both curves. Cam LSAs ??