Too big of a cylinder head...

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kimosabi
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Re: Too big of a cylinder head...

Post by kimosabi » Tue Feb 06, 2018 4:58 pm

200-220cc head on a 350+ci sbc isn't really that big. We see a whole lot of people running 195-200cc port volume on 350's running well these days but not that many years ago you'd be ridiculed if you did that. Head development, and not to forget engine building, have evolved. It's not the small GM castings with a huge cam anymore. With the older heads you had to run a big cam, help the cylinder fill any way you can. Bigger ports pretty much all you have to worry about is to keep the speed up and that's where a good cam grinder comes in. Major benefit is the valvetrain happiness.

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Re: Too big of a cylinder head...

Post by MadBill » Tue Feb 06, 2018 10:53 pm

This Engine Masters episode compares AFR 165, 195 and 220 cc heads on a 410" SBF with a ~ 0.500" lift 218/224° cam: https://www.youtube.com/watch?v=p1w8OU_8-JM
(SPOILER ALERT!)
The 165 and 220 made pretty much exactly the same power through the entire pull, while the 195 cc was up 13 HP at the peak. :-k
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Re: Too big of a cylinder head...

Post by Kenova » Tue Feb 06, 2018 10:59 pm

MadBill wrote:
Tue Feb 06, 2018 10:53 pm
This Engine Masters episode compares AFR 165, 195 and 220 cc heads on a 410" SBF with a ~ 0.500" lift 218/224° cam: https://www.youtube.com/watch?v=p1w8OU_8-JM
(SPOILER ALERT!)
The 165 and 220 made pretty much exactly the same power through the entire pull, while the 195 cc was up 13 HP at the peak.
..........Which means that going with too big of a cylinder head is more like dropping a half empty jar of peanut butter on your foot than shooting yourself in the foot.

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Re: Too big of a cylinder head...

Post by statsystems » Tue Feb 06, 2018 11:11 pm

Kenova wrote:
Tue Feb 06, 2018 10:59 pm
MadBill wrote:
Tue Feb 06, 2018 10:53 pm
This Engine Masters episode compares AFR 165, 195 and 220 cc heads on a 410" SBF with a ~ 0.500" lift 218/224° cam: https://www.youtube.com/watch?v=p1w8OU_8-JM
(SPOILER ALERT!)
The 165 and 220 made pretty much exactly the same power through the entire pull, while the 195 cc was up 13 HP at the peak.
..........Which means that going with too big of a cylinder head is more like dropping a half empty jar of peanut butter on your foot than shooting yourself in the foot.

Ken
Or, as is typical of stuff like this the bigger head could have used a smaller cam, made all,the power back and then some. It's horrible to test the way they are doing it.

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Re: Too big of a cylinder head...

Post by MadBill » Wed Feb 07, 2018 12:01 am

Yes, ideally they'd have used maybe three cams, two at least, but the test matrix can get out of control in a hurry..
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Re: Too big of a cylinder head...

Post by randy331 » Wed Feb 07, 2018 12:27 am

How do you decide if it's head size or the different port shape that made any power difference on these types of tests?

I mean if you add valve size and throat size, but leave the MCSA the same, you still added cc to the head.
If you add area to the MCSA but leave the valve/throat/bowl the same you added cc.
Within any casting you have limits of where you can add CC.

How do you decide the "CC" was responsible for any power difference???

Is there a test where a 180-200-220 cc heads were tested, where they were all exact copies, but with everything sized proportionally different????

Randy

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Re: Too big of a cylinder head...

Post by kimosabi » Wed Feb 07, 2018 3:44 am

Kenova wrote:
Tue Feb 06, 2018 10:59 pm
MadBill wrote:
Tue Feb 06, 2018 10:53 pm
This Engine Masters episode compares AFR 165, 195 and 220 cc heads on a 410" SBF with a ~ 0.500" lift 218/224° cam: https://www.youtube.com/watch?v=p1w8OU_8-JM
(SPOILER ALERT!)
The 165 and 220 made pretty much exactly the same power through the entire pull, while the 195 cc was up 13 HP at the peak.
..........Which means that going with too big of a cylinder head is more like dropping a half empty jar of peanut butter on your foot than shooting yourself in the foot.

Ken
It shows the common knowledge nowadays that the cam they used were better suited to the 195 head than the others. Nothing else. Anyone questioning the importance of a custom grind to your combo after watching that test, should start thinking about doing something else than engine building.

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Re: Too big of a cylinder head...

Post by Bos's5.0 » Wed Feb 07, 2018 10:00 am

I think they also should have used a 302, and not a 410. They used way too big an engine to test that theory, but it was probably the only Ford within driving distance of Chevtech.... I mean Westech.

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Re: Too big of a cylinder head...

Post by randy331 » Wed Feb 07, 2018 11:11 am

kimosabi wrote:
Wed Feb 07, 2018 3:44 am
It shows the common knowledge nowadays that the cam they used were better suited to the 195 head than the others. Nothing else. Anyone questioning the importance of a custom grind to your combo after watching that test, should start thinking about doing something else than engine building.
How could you watch that video and come to that conclusion, or really any useful conclusion ??

Randy

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Re: Too big of a cylinder head...

Post by racin69z » Wed Feb 07, 2018 10:16 pm

I too thought it was kind of odd to use a 410 inch engine. A 302 or even a 351 would have been a more realistic test.


The l92 head 6.0 or 6.2 whichever they are seem to run pretty good in 3/4 ton trucks.

I was thinking hard about putting my 220 cc pro actions on my blazer motor but decided to just stick with the vortecs. But i think it would be a blast at higher rpm.

Lynn

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Re: Too big of a cylinder head...

Post by RDY4WAR » Wed Feb 07, 2018 10:47 pm

When you compare that with a BBF with stock intake port size of ~270cc, you get...

270 / (460/8) = 4.7 cc/ci

165 / (410/8) = 3.2 cc/ci
195 / (410/8) = 3.8 cc/ci
220 / (410/8) = 4.3 cc/ci

Now of course this doesn't take MCSA and runner length into account, only volume.

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Re: Too big of a cylinder head...

Post by Orr89rocz » Thu Feb 08, 2018 7:28 am

Bos's5.0 wrote:
Wed Feb 07, 2018 10:00 am
I think they also should have used a 302, and not a 410. They used way too big an engine to test that theory, but it was probably the only Ford within driving distance of Chevtech.... I mean Westech.
I dont think it matters. In the 410 i would have expected the 220 to be the right size head and make as much if not more power than the other 2, but that is a cam i would run in a 302, not a 410 so perhaps the 195 port size just was best for that particular cam and cubes

Do that test again but with a cam that has another 15-20 deg duration at .050 and abit more lift, the results should skew toward the bigger head imo

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Re: Too big of a cylinder head...

Post by Bos's5.0 » Thu Feb 08, 2018 9:40 am

Orr89rocz wrote:
Thu Feb 08, 2018 7:28 am
Bos's5.0 wrote:
Wed Feb 07, 2018 10:00 am
I think they also should have used a 302, and not a 410. They used way too big an engine to test that theory, but it was probably the only Ford within driving distance of Chevtech.... I mean Westech.
I dont think it matters. In the 410 i would have expected the 220 to be the right size head and make as much if not more power than the other 2, but that is a cam i would run in a 302, not a 410 so perhaps the 195 port size just was best for that particular cam and cubes

Do that test again but with a cam that has another 15-20 deg duration at .050 and abit more lift, the results should skew toward the bigger head imo
You have a couple problems. The intake was too small from the start and the 220 head has the biggest valves (2.100x1.57) combined with the relatively small bore of the 351 could easily have caused a bit of shrouding.
Changing just one component in the middle of a complex air processing system is a bad practice.

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Re: Too big of a cylinder head...

Post by Orr89rocz » Thu Feb 08, 2018 11:03 am

Bos's5.0 wrote:
Thu Feb 08, 2018 9:40 am
Orr89rocz wrote:
Thu Feb 08, 2018 7:28 am
Bos's5.0 wrote:
Wed Feb 07, 2018 10:00 am
I think they also should have used a 302, and not a 410. They used way too big an engine to test that theory, but it was probably the only Ford within driving distance of Chevtech.... I mean Westech.
I dont think it matters. In the 410 i would have expected the 220 to be the right size head and make as much if not more power than the other 2, but that is a cam i would run in a 302, not a 410 so perhaps the 195 port size just was best for that particular cam and cubes

Do that test again but with a cam that has another 15-20 deg duration at .050 and abit more lift, the results should skew toward the bigger head imo
You have a couple problems. The intake was too small from the start and the 220 head has the biggest valves (2.100x1.57) combined with the relatively small bore of the 351 could easily have caused a bit of shrouding.
Changing just one component in the middle of a complex air processing system is a bad practice.
Never said it was a good test. Just saying if it was a 302 i dont think that makes the test that much better.

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Re: Too big of a cylinder head...

Post by digger » Thu Feb 08, 2018 4:22 pm

To properly test This you need to use multiple test mules. The next one I'd do is less cubes and more cam

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