Is the stock 4V cast intake good to 6500rpm???

Is the stock 4V cast intake good to 6500rpm???

Joined: January 26th, 2011, 10:15 pm

May 29th, 2012, 10:34 pm #1


Is the stock cast-iron 351c 4V intake manifold good up to 6500 rpms?  The following article says so, but tons of people on this forum say 5500 rpm max.  Who's right? 

http://www.mustangandfords.com/techarti ... index.html

yes, this article has numbers for the supercharger too, but below is stock intake with XE284H camshaft and headers.

351C produced 447 hp at 6,400 rpm and 411 lb-ft of torque at 5,200


Thanks.
Jim


Jim
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Joined: January 1st, 1970, 12:00 am

May 30th, 2012, 3:01 am #2

I would think so, I know I had my old iron one up on the rpms, the fuel line and pump usually give out around that point too, even if you have enough cam to rev that high.

give it a try and report back, whats the rest of your build look like?
~blizz



Happy New Year 2012!!..
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Joined: January 1st, 1970, 12:00 am

May 30th, 2012, 3:08 am #3

I was going to pull up a wiki link for him, but I have nothing there to pull up..
Help?? Dan? George? Tin? anyone? Bueller? Bueller?

~blizz

Happy New Year 2012!!..
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Joined: January 26th, 2011, 10:15 pm

May 30th, 2012, 4:21 am #4

I would think so, I know I had my old iron one up on the rpms, the fuel line and pump usually give out around that point too, even if you have enough cam to rev that high.

give it a try and report back, whats the rest of your build look like?
~blizz



Happy New Year 2012!!..
Blizz,  The rest of my build is as follows:
1971 4V CC heads with mild port job.

Intake
.100=68
.200=138
.300=201
.400=243
.500=276
.600=296
.700=304

Exhaust
.100=52
.200=96
.300=130
.400=154
.500=170
.600=176
.700=176


The cam is Crane H-278-2 cam  Crane recommends matching components Minimum RPM at 2200, Max RPM at 5800 and Valve float at 6400 RPM.

Exhaust will be Sanderson shorty headers and 2.5" exhaust.

Which intake shoud I use?  Stock D0AE, EDL RPM air gap or Blue thunder?

Thanks!


Jim
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Joined: October 1st, 2004, 8:05 pm

May 30th, 2012, 6:07 am #5

You've chosen a good cam. The quench 4V heads are another good choice.

Use the Blue Thunder manifold. Once the carb & ignition are dialed in you'll love the motor's performance.

If not, I'll buy the manifold from you.


-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
Last edited by gpence on May 30th, 2012, 6:08 am, edited 1 time in total.
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Joined: February 17th, 2004, 11:02 pm

May 30th, 2012, 3:53 pm #6

Is the stock cast-iron 351c 4V intake manifold good up to 6500 rpms?  The following article says so, but tons of people on this forum say 5500 rpm max.  Who's right? 

http://www.mustangandfords.com/techarti ... index.html

yes, this article has numbers for the supercharger too, but below is stock intake with XE284H camshaft and headers.

351C produced 447 hp at 6,400 rpm and 411 lb-ft of torque at 5,200


Thanks.
Jim


Jim
> Is the stock cast-iron 351c 4V intake manifold good up to 6500 rpms?

Will it rev there? Maybe. Will it make good pwer there? No.
See dyno data below.

> Exhaust will be Sanderson shorty headers and 2.5" exhaust.

Pantera shorty headers give up some low end but tested surprisingly well
on the top end. The mufflers have been the biggest restriction. The
Pantera ANSA mufflers lost 50 HP on a 400+ HP 351C in our dyno testing.
The last round of testing used 2 1/2" Magnaflows which did quite well
on my 403C (569 HP through the mufflers with a hydraulic roller cam,
Pantera headers and Scott Cook dual plane).

> Which intake shoud I use? Stock D0AE, EDL RPM air gap or Blue Thunder?

Ditch the stock intake. If you need carb heat, go with at least an Edelbrock
Performer and 1" HVH spacer. The Air Gap 2V with 1" 4 hole spacer will be
better yet but has no provisions for carb heat and is quite tall. Out-of-the-box,
the Blue Thunder has been disappointing but when worked on the flow bench to
equalize the runners, is one of the best all around intakes and has provisions
for carb heat and a choke loop (works much better than an electric choke).
We didn't do a direct comparison with the Blue Thunder on the test engine in
the dyno data below becuase the there was clearance issue (BT wouldn't clear
the distributor cap). In other testing, the ported intake picked up from 15
to 45 HP over the baseline. Scott Cook's dual plane would be excellent
out-of-the-box too.

Dan Jones

Factory 4V Iron Intake
Holley 950HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Same as baseline except for running factory 4V iron square bore intake manifold
and 4 hole 1 inch spacer. The OEM intake required a spacer for throttle
clearance so was tested only with 1" spacers. Not a really good pull but
engine had time to cool. Going to try one more time but seems to be down
about 30HP from our baseline with the single plane Torker.

RPM Hp Torque
(HP) (ft-lb)
4000 273.9 356.1
4100 279.8 361.1
4200 276.3 345.9
4300 279.2 341
4400 285.6 340.8
4500 294.2 343.3
4600 304.5 347.6
4700 316.1 352.8
4800 326.1 356.3
4900 324.6 346.4
5000 328 344.6
5100 332.6 342.7
5200 335.5 339
5300 340.9 337.7
5400 351.1 340.8
5500 353.9 338.5
5600 349.2 327.7
5700 346.8 319.6
5800 349.8 316.4
5900 353.9 316.1


Factory Iron Test 2 - Same as 1st
Same as previous run. Engine seems to be somewhat rougher and more difficult
to load properly. 12.5 AFR. Going to try an HVH spacer on next pull to see
if it smooths it out somewhat.

RPM Hp Torque
(HP) (ft-lb)
4000 283.8 369.6
4100 282.7 361.8
4200 279.5 349.8
4300 283.5 346.3
4400 289.4 345.5
4700 313.8 350.4
4800 323.5 353.7
4900 334.7 358.1
5000 342.3 360.1
5100 344.5 354.9
5200 347.2 350.6
5300 350.7 347.5
5400 349.1 339.7
5500 348.3 332.4
5600 345.9 324.6
5700 351.2 324.5
5800 332 301

Factory Iron with HVH Spacer
OEM square bore intake, Pantera GTS headers and Magnaflow mufflers.
Much better with the semi open spacer under carburetor. Most likely due to the
amount of camshaft overlap and the interaction it has with the dual plane type
intake. It will be very interesting to see if this trend continues with the
other larger dual planes.

RPM Hp Torque
(HP) (ft-lb)
4000 278.9 362.6
4100 285 365.7
4200 288.2 360.5
4300 296.6 362.2
4400 304.1 362.9
4500 310.9 363
4600 318.7 364.1
4700 326.1 364.5
4800 335.4 366.4
4900 341.9 366.8
5000 345.4 363
5100 350.5 360.7
5200 355.8 359.4
5300 360.4 356.9
5400 362.3 352.6
5500 362.7 346.3
5600 364.9 341.8
5700 362.7 334.8
5800 356.9 323.3
5900 358.3 318.8
6000 363.1 317.9
6100 355.4 305.9


Performer with 4 Hole 1 Inch Spacer
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Note: Intake is actually the earlier F-351 4V version but appears identical to
the current Performer. The Perfomrer required a spacer for throttle clearance
so was tested only with 1" spacers. Baseline for Edelbrock Performer intake
with 4 hole 1 inch spacer which was needed to allow clearance for fuel log.
Good solid pull and for whatever reason the engine didn't seem to mind the 1
inch 4 hole on this dual plane. Going to try the HVH spacer next.

RPM Hp Torque
(HP) (ft-lb)
4100 285.7 365.8
4200 288.8 361.5
4300 298 363.8
4400 304.5 363.6
4500 309.1 361.1
4600 315.7 360.5
4700 325 362.8
4800 333.3 365.2
4900 337.7 361.9
5000 341.1 358
5100 344.8 355.2
5200 350.3 353.5
5300 352 349.4
5400 354.9 345.2
5500 359.5 343.1
5600 363.1 340.1
5700 363.2 335.3
5800 356.8 323.1
5900 354.2 314.9
6000 345.7 302.8
6100 352.9 303.2


Performer with HVH Spacer
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
HVH was also better on the Edelbrock Performer but not as drastic as with the
factory iron piece. Performer is better than factory intake or so it seems
on this engine.

RPM Hp Torque
(HP) (ft-lb)
4100 293.4 373
4200 295.9 371.5
4300 307.1 376
4400 309.1 369.3
4500 314.9 367.7
4600 323 368.9
4700 332.7 371.6
4800 343.9 375.9
4900 353.6 378.6
5000 353.4 371.5
5100 357.4 368
5200 360.2 364.2
5300 359.7 356.7
5400 362.5 352.5
5500 366.8 350
5600 369.8 346.5
5700 371.8 342.4
5800 371.5 336.5
5900 372.5 331.6
6000 364.2 318.9
6100 365.9 315.3


Performer RPM Air Gap 2V
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Baseline for Performer RPM airgap intake. Like many of the intakes designed
for 2V heads, the RPM Air Gap will fit either 2V or 4V heads. Running with
no spacer. Going to try the 4 hole 1 inch and HVH spacers next. Good solid
pull with good numbers.

RPM Hp Torque
(HP) (ft-lb)
4000 297.5 386.4
4100 297 382.7
4200 305.4 380.9
4300 313.4 383.5
4400 319.8 381.8
4500 328.4 383
4600 334 381.6
4700 338.9 378.7
4800 345.4 377.8
4900 352.4 377.7
5000 358.3 376.3
5100 363.6 374.4
5200 368.3 371.8
5300 371.7 368.8
5400 374.2 363.9
5500 379.1 361.9
5600 377.8 354.4
5700 375.8 346.3
5800 373.9 338.7
5900 374.5 333.4
6000 377.7 330.4
6100 375.5 323.2


Performer RPM Air Gap with HVH
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
HVH spacer seems to run about in the middle of the bare intake or 4 hole 1
inch. Good all around performance making over 380HP and torque.

RPM Hp Torque
(HP) (ft-lb)
4100 295.3 381.7
4200 299.8 375.3
4300 308.6 376.9
4400 321 382.8
4500 333 388.5
4600 337.3 385.3
4700 343 383.1
4800 349.8 382.7
4900 355.8 381.3
5000 359.2 377.6
5100 363.1 373.9
5200 370 373.4
5300 374.2 371.3
5400 376.5 366.1
5500 381 363.3
5600 380.1 357.1
5700 372.2 343
5800 370.2 335.1
5900 367.6 327.3
6000 365.8 320.2
6100 368.5 317


Performer RPM Air Gap with 4 hole 1 Inch
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Good pull and engine picked up about 5 horsepower and about 10lbs/ft with 4
hole. A good swap and about the best all around combo for these heads etc.

RPM Hp Torque
(HP) (ft-lb)
4000 298 389.8
4100 301.5 387.1
4200 308.9 385.4
4300 316.9 388
4400 329.8 391.1
4500 332.6 388.7
4600 337.2 385.1
4700 345.5 385.8
4800 353.6 387
4900 357.2 383
5000 362.2 380.3
5100 369.4 380.1
5200 375.3 379.1
5300 376.5 373.2
5400 379.6 369.2
5500 382.5 365.1
5600 384.1 360.3
5700 381.7 351.8
5800 382.6 346.4
5900 382 340.2
6000 383.9 335.7
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Joined: February 28th, 2008, 4:15 pm

May 30th, 2012, 5:07 pm #7

I have used these several times and they work pretty good. I have worked the plenum area to remove the 4 hole style opening and make it more open. Helps flow and works better with spacers. I use a sawsall with metal cutting blades. Takes about 30 minutes and several blades to cut the lower plenum side and then do some smoothing with a die grinder.
Andy

Picture of plenum work but on a 429SCJ imntake.

[/IMG]
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Joined: February 2nd, 2003, 3:52 am

May 30th, 2012, 8:17 pm #8

> Is the stock cast-iron 351c 4V intake manifold good up to 6500 rpms?

Will it rev there? Maybe. Will it make good pwer there? No.
See dyno data below.

> Exhaust will be Sanderson shorty headers and 2.5" exhaust.

Pantera shorty headers give up some low end but tested surprisingly well
on the top end. The mufflers have been the biggest restriction. The
Pantera ANSA mufflers lost 50 HP on a 400+ HP 351C in our dyno testing.
The last round of testing used 2 1/2" Magnaflows which did quite well
on my 403C (569 HP through the mufflers with a hydraulic roller cam,
Pantera headers and Scott Cook dual plane).

> Which intake shoud I use? Stock D0AE, EDL RPM air gap or Blue Thunder?

Ditch the stock intake. If you need carb heat, go with at least an Edelbrock
Performer and 1" HVH spacer. The Air Gap 2V with 1" 4 hole spacer will be
better yet but has no provisions for carb heat and is quite tall. Out-of-the-box,
the Blue Thunder has been disappointing but when worked on the flow bench to
equalize the runners, is one of the best all around intakes and has provisions
for carb heat and a choke loop (works much better than an electric choke).
We didn't do a direct comparison with the Blue Thunder on the test engine in
the dyno data below becuase the there was clearance issue (BT wouldn't clear
the distributor cap). In other testing, the ported intake picked up from 15
to 45 HP over the baseline. Scott Cook's dual plane would be excellent
out-of-the-box too.

Dan Jones

Factory 4V Iron Intake
Holley 950HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Same as baseline except for running factory 4V iron square bore intake manifold
and 4 hole 1 inch spacer. The OEM intake required a spacer for throttle
clearance so was tested only with 1" spacers. Not a really good pull but
engine had time to cool. Going to try one more time but seems to be down
about 30HP from our baseline with the single plane Torker.

RPM Hp Torque
(HP) (ft-lb)
4000 273.9 356.1
4100 279.8 361.1
4200 276.3 345.9
4300 279.2 341
4400 285.6 340.8
4500 294.2 343.3
4600 304.5 347.6
4700 316.1 352.8
4800 326.1 356.3
4900 324.6 346.4
5000 328 344.6
5100 332.6 342.7
5200 335.5 339
5300 340.9 337.7
5400 351.1 340.8
5500 353.9 338.5
5600 349.2 327.7
5700 346.8 319.6
5800 349.8 316.4
5900 353.9 316.1


Factory Iron Test 2 - Same as 1st
Same as previous run. Engine seems to be somewhat rougher and more difficult
to load properly. 12.5 AFR. Going to try an HVH spacer on next pull to see
if it smooths it out somewhat.

RPM Hp Torque
(HP) (ft-lb)
4000 283.8 369.6
4100 282.7 361.8
4200 279.5 349.8
4300 283.5 346.3
4400 289.4 345.5
4700 313.8 350.4
4800 323.5 353.7
4900 334.7 358.1
5000 342.3 360.1
5100 344.5 354.9
5200 347.2 350.6
5300 350.7 347.5
5400 349.1 339.7
5500 348.3 332.4
5600 345.9 324.6
5700 351.2 324.5
5800 332 301

Factory Iron with HVH Spacer
OEM square bore intake, Pantera GTS headers and Magnaflow mufflers.
Much better with the semi open spacer under carburetor. Most likely due to the
amount of camshaft overlap and the interaction it has with the dual plane type
intake. It will be very interesting to see if this trend continues with the
other larger dual planes.

RPM Hp Torque
(HP) (ft-lb)
4000 278.9 362.6
4100 285 365.7
4200 288.2 360.5
4300 296.6 362.2
4400 304.1 362.9
4500 310.9 363
4600 318.7 364.1
4700 326.1 364.5
4800 335.4 366.4
4900 341.9 366.8
5000 345.4 363
5100 350.5 360.7
5200 355.8 359.4
5300 360.4 356.9
5400 362.3 352.6
5500 362.7 346.3
5600 364.9 341.8
5700 362.7 334.8
5800 356.9 323.3
5900 358.3 318.8
6000 363.1 317.9
6100 355.4 305.9


Performer with 4 Hole 1 Inch Spacer
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Note: Intake is actually the earlier F-351 4V version but appears identical to
the current Performer. The Perfomrer required a spacer for throttle clearance
so was tested only with 1" spacers. Baseline for Edelbrock Performer intake
with 4 hole 1 inch spacer which was needed to allow clearance for fuel log.
Good solid pull and for whatever reason the engine didn't seem to mind the 1
inch 4 hole on this dual plane. Going to try the HVH spacer next.

RPM Hp Torque
(HP) (ft-lb)
4100 285.7 365.8
4200 288.8 361.5
4300 298 363.8
4400 304.5 363.6
4500 309.1 361.1
4600 315.7 360.5
4700 325 362.8
4800 333.3 365.2
4900 337.7 361.9
5000 341.1 358
5100 344.8 355.2
5200 350.3 353.5
5300 352 349.4
5400 354.9 345.2
5500 359.5 343.1
5600 363.1 340.1
5700 363.2 335.3
5800 356.8 323.1
5900 354.2 314.9
6000 345.7 302.8
6100 352.9 303.2


Performer with HVH Spacer
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
HVH was also better on the Edelbrock Performer but not as drastic as with the
factory iron piece. Performer is better than factory intake or so it seems
on this engine.

RPM Hp Torque
(HP) (ft-lb)
4100 293.4 373
4200 295.9 371.5
4300 307.1 376
4400 309.1 369.3
4500 314.9 367.7
4600 323 368.9
4700 332.7 371.6
4800 343.9 375.9
4900 353.6 378.6
5000 353.4 371.5
5100 357.4 368
5200 360.2 364.2
5300 359.7 356.7
5400 362.5 352.5
5500 366.8 350
5600 369.8 346.5
5700 371.8 342.4
5800 371.5 336.5
5900 372.5 331.6
6000 364.2 318.9
6100 365.9 315.3


Performer RPM Air Gap 2V
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Baseline for Performer RPM airgap intake. Like many of the intakes designed
for 2V heads, the RPM Air Gap will fit either 2V or 4V heads. Running with
no spacer. Going to try the 4 hole 1 inch and HVH spacers next. Good solid
pull with good numbers.

RPM Hp Torque
(HP) (ft-lb)
4000 297.5 386.4
4100 297 382.7
4200 305.4 380.9
4300 313.4 383.5
4400 319.8 381.8
4500 328.4 383
4600 334 381.6
4700 338.9 378.7
4800 345.4 377.8
4900 352.4 377.7
5000 358.3 376.3
5100 363.6 374.4
5200 368.3 371.8
5300 371.7 368.8
5400 374.2 363.9
5500 379.1 361.9
5600 377.8 354.4
5700 375.8 346.3
5800 373.9 338.7
5900 374.5 333.4
6000 377.7 330.4
6100 375.5 323.2


Performer RPM Air Gap with HVH
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
HVH spacer seems to run about in the middle of the bare intake or 4 hole 1
inch. Good all around performance making over 380HP and torque.

RPM Hp Torque
(HP) (ft-lb)
4100 295.3 381.7
4200 299.8 375.3
4300 308.6 376.9
4400 321 382.8
4500 333 388.5
4600 337.3 385.3
4700 343 383.1
4800 349.8 382.7
4900 355.8 381.3
5000 359.2 377.6
5100 363.1 373.9
5200 370 373.4
5300 374.2 371.3
5400 376.5 366.1
5500 381 363.3
5600 380.1 357.1
5700 372.2 343
5800 370.2 335.1
5900 367.6 327.3
6000 365.8 320.2
6100 368.5 317


Performer RPM Air Gap with 4 hole 1 Inch
950 HP dyno carb, Pantera GTS headers and Magnaflow mufflers.
Good pull and engine picked up about 5 horsepower and about 10lbs/ft with 4
hole. A good swap and about the best all around combo for these heads etc.

RPM Hp Torque
(HP) (ft-lb)
4000 298 389.8
4100 301.5 387.1
4200 308.9 385.4
4300 316.9 388
4400 329.8 391.1
4500 332.6 388.7
4600 337.2 385.1
4700 345.5 385.8
4800 353.6 387
4900 357.2 383
5000 362.2 380.3
5100 369.4 380.1
5200 375.3 379.1
5300 376.5 373.2
5400 379.6 369.2
5500 382.5 365.1
5600 384.1 360.3
5700 381.7 351.8
5800 382.6 346.4
5900 382 340.2
6000 383.9 335.7
Dan,

Who would you recommend to do the work on a BT? I have the Shelby version and plan to use it on a C build one day.
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Joined: February 17th, 2004, 11:02 pm

May 30th, 2012, 8:21 pm #9

Dave McLain at McLain's Automotive in Cuba, Missouri. He's the one who modified the ones we've tested. I'm sending a Blue Thunder down this week. Make sure he knows the particulars of your combo and whether you can use a 1" spacer. Dan
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Joined: October 1st, 2004, 8:05 pm

May 30th, 2012, 9:01 pm #10

Dan,

Who would you recommend to do the work on a BT? I have the Shelby version and plan to use it on a C build one day.
Suggestion ... drive the car with the unmodified manifold before you have it modified.

If you ever decide to sell the Shelby manifold you'll get more money for it if it is unmodified.

-G
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