should my engine be quitting at 5900 rpm or should it keep making power?

jerry S

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Sep 3, 2003

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Dec 5, 2005

#1

• Dec 5, 2005

• #1

Here is my cam card http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=15237&x=39&y=6

I have a 351W

 

5

57fairlane

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#2

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• #2

jerry S said:

Here is my cam card http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=15237&x=39&y=6

I have a 351W

Click to expand...

I would guess 6400-6500 in a 351. 15 degrees of overlap is pretty good.

 

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1966conv

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That's an open ended question without knowing the rest of your components. (ie heads, intake, carb, exhaust)

 

thehueypilot

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#4

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It will make power until the valves float or the engine lets go....which ever comes first. Roller hyd lifters will float around 6.5-7k.

 

chepsk8

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#5

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With stock heads, that's it. They usually choke right about 5500 RPM

 

jerry S

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1966conv said:

That's an open ended question without knowing the rest of your components. (ie heads, intake, carb, exhaust)

Click to expand...

I have edelbrock rpm performer cylinder heads, an edelbrock rpm air gap, and a holley 650 cfm 4bbl with an electric fuel pump and fuel pressure regulator, long tube headers, and a 2.5 inch dual exhaust.

 

LMan

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#7

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what valve springs?

 

jerry S

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LMan said:

what valve springs?

Click to expand...

whatever edelbrock has in the heads. I know that they are a single spring. I sent edelbrock the cam card and told them the cylinder heads I have. I got an email back saying that the springs can take the lift from that cam.

 

HistoricMustang

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jerry S said:

I have edelbrock rpm performer cylinder heads, an edelbrock rpm air gap, and a holley 650 cfm 4bbl with an electric fuel pump and fuel pressure regulator, long tube headers, and a 2.5 inch dual exhaust.

Click to expand...

With a 351 that is pretty close. For a 289 add 300 to 400 more RPM's before the PULLING will stop with a stock bottom end. (Yes, they will rev higher)

HistoricMustang
www.historicmustang.com

 

jerry S

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HistoricMustang said:

With a 351 that is pretty close. For a 289 add 300 to 400 more RPM's before the PULLING will stop with a stock bottom end. (Yes, they will rev higher)

HistoricMustang
www.historicmustang.com

Click to expand...

Thanks. I can check that off the list of things to be concerned about.

 

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86bluecobra

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Dec 20, 2004

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#11

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if you upgrade the springs in the heads it should pull longer. the dual plane intake doesn't help either for wanting to pull higher. my 351w pulls more then 5900rpm (propably just a few hundred rpm more)i have a stealth dual plane intake and holley systemax II heads. i shift around 6500rpm at track. i also have a 750 holley and 150 hp shot of juice so it seems to pull better on the juice.

 

jerry S

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#12

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86bluecobra said:

if you upgrade the springs in the heads it should pull longer. the dual plane intake doesn't help either for wanting to pull higher. my 351w pulls more then 5900rpm (propably just a few hundred rpm more)i have a stealth dual plane intake and holley systemax II heads. i shift around 6500rpm at track. i also have a 750 holley and 150 hp shot of juice so it seems to pull better on the juice.

Click to expand...

I had a single plane on there before (Torker II). Everyone said it was junk and to get the Air Gap so I pulled it and put the Air Gap on there. I lost low end torque at 2600 rpm (Torker II made 200 ft lbs torque at 2600 while the Air Gap makes 175 ft lbs). I make 390 ft lbs at 3600 rpm with the Air Gap compared to 380 with the Torker II at 3600 and peak torque for the Air Gap is 399 ft lbs compared to 386 ft lbs with the torker II. Both the single and double plane intakes are dying off at the same RPM point in terms of hp and torque. So in other words, empirical evidence shows that there is no difference between the two intakes in terms of top end.

And as far as upgrading the springs, I am told by the dyno tuner that double springs will indeed be stronger but that with them being that much harder to open, I will lose power immediately with a double spring on there.

 

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67gt

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#13

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I read somewhere that you don’t actually loose power with stiffer springs. When the cam is pushing up on a lifter, another lifter is pushing back down on the cam with equal force. So essentially the forces of the springs are canceled out.

 

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86bluecobra

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#14

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i believe the torker II is old technology. the victor jr is a better single plane intake. as a rule dual planes do make more lowend torque however i would bet that the victor jr on the 351w crate motor from ford that makes 385 ponies was the better intake for them to put on there crate engine then a dual plane intake. I looked at your cam specs and according to crower your cam power range stops at 6000 rpm. so it is no wonder you feel it stop pulling right around that mark.

 

69Rcode_Mach1

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#15

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I agree that sounds about right Jerry. A 351 will not spin as high as the smaller displacement engines, and 5900 is not bad at all. It would put your shift points around 6300-6400 depending on how fast the curve drops off.

 

jerry S

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#16

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69Rcode_Mach1 said:

I agree that sounds about right Jerry. A 351 will not spin as high as the smaller displacement engines, and 5900 is not bad at all. It would put your shift points around 6300-6400 depending on how fast the curve drops off.

Click to expand...

I am ignorant as to my shift points. I figured that since my engine stops making power at 5900, I would just put in a 6K rev limiter in there. Why would I shift at 6300-6400 when I am out of my power band? Or is that exactly what you want to do? I have no idea so please educate me.

 

rbohm

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#17

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jerry S said:

I am ignorant as to my shift points. I figured that since my engine stops making power at 5900, I would just put in a 6K rev limiter in there. Why would I shift at 6300-6400 when I am out of my power band? Or is that exactly what you want to do? I have no idea so please educate me.

Click to expand...

the reason you want to shift just above your power peak, is so that when engine rpm drops you are just below the power peak, and you dont have to wait for the engine to accelerate to where it is close to the power peak again. usually you want the engine to accelerate between 500rpm below to 500 rpm above the power peak for best acceleration. you can narrow that or widen it as needed for best times at the track.

 

69Rcode_Mach1

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#18

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Yep basically if the power is not dropping off fast it will maintain it well enough for you too keep going. That in turn will allow you to stay higher up in the powerband on your next shift. Basically you want to shift so that you near or at your torque peak in the next gear. This will lead to better 1/4 mile times.