When will people learn engine config means nothing on output?

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I read time after time these silly comments...

Ah, the high torque of a V-twin...
Wow, those inline 4's really scream, but they have no torque...
Wow, those single thumpers really pound out the low RPM power...
OMGosh, the V4 is the perfect combo of low end torque and high end HP!!!!

Please for the love of all that is holy in the land of IC engines, the mechanical arrangement of the cylinders has almost ZERO effect on power/torque characteristics of the engine!!!!

Yes, there is a propensity to design a certain number of cylinders with a certain power profile, usually due to the application that engine was designed for...but it is all in the bore/stroke and cam profiles that determines it's power profile.

You can have super low revving V-8 torque monsters, super high revving and high HP singles, and everything in between. The physical arrangement of the cylinders doesn't have much of any change on the power profile. Just look at the Honda engine in an RC51 and that of a Harley. Both are V-twins...one with peak HP over 10,000 rpms, and one with peak power around 6,000 rpms. The Honda engine doesn't even make peak torque before the Harley is pretty much at the redline.

Let's not even get started on push rods vs overhead cams...
 
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I am amused by the "wimpy 3 cylinder" comments when modern 3 cylinders or small displacement 4 cylinders make more power and torque than a 5L+ V8 in the 70s. I once drove an Isuzu box truck for a few months for work that was powered by a massive 5.2L Inline 4 diesel and I assure you it had plenty of low end torque and a redline of barely over 2500RPM.

That said, on OHC vs OHV there is ~some~ reasoning there but it mostly has to do with the fact that modern OHC engines are 4 valve per cylinder and OHV engines are 2. That lends OHV engines toward low-end torque profiles and worse breathing at high RPMs, while 4 valve per cylinders tend to have better high end pull. Rather than being inherent in OHC/OHV designs it's more inherent in the number of valves and breathing ability.
 
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yea my turbo I-4 2L has about 25% more torque and lower redline
than the V6 3.2L pentastar.
They both have their advantages and disadvantages.
 
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I am amused by the "wimpy 3 cylinder" comments when modern 3 cylinders or small displacement 4 cylinders make more power and torque than a 5L+ V8 in the 70s. I once drove an Isuzu box truck for a few months for work that was powered by a massive 5.2L Inline 4 diesel and I assure you it had plenty of low end torque and a redline of barely over 2500RPM.

That said, on OHC vs OHV there is ~some~ reasoning there but it mostly has to do with the fact that modern OHC engines are 4 valve per cylinder and OHV engines are 2. That lends OHV engines toward low-end torque profiles and worse breathing at high RPMs, while 4 valve per cylinders tend to have better high end pull. Rather than being inherent in OHC/OHV designs it's more inherent in the number of valves and breathing ability.
Well, while the Ford 1L I3 GTDI is a weezer(unless it’s in a Focus RS/Fiesta RS), the one Toyota is using in the GR Yaris in Japan and Europe is a screamer - and it has some commonality with their new Dynamic Force family. GM has managed to keep the pushrod alive and even rival the best from Europe for output. The RAV4 I’m renting now is surprisingly nice for a NA 2.5L I4 - it feels like a Toyota V6/V8 from the 1990s-early 2000s.

I’m sure Ford used the 2V OHV reasoning for the new 7.3L gasser V8 and it’s target application - box vans, school buses, paratransit vans and RVs built on E-series cutaway chassis and fleets who need diesel torque but no SCR/DEF/DPF nightmares. But isn’t Cummins using a 4V OHV layout for their 7-12L class engines?
 
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Well, while the Ford 1L I3 GTDI is a weezer(unless it’s in a Focus RS/Fiesta RS), the one Toyota is using in the GR Yaris in Japan and Europe is a screamer - and it has some commonality with their new Dynamic Force family. GM has managed to keep the pushrod alive and even rival the best from Europe for output. The RAV4 I’m renting now is surprisingly nice for a NA 2.5L I4 - it feels like a Toyota V6/V8 from the 1990s-early 2000s.

I’m sure Ford used the 2V OHV reasoning for the new 7.3L gasser V8 and it’s target application - box vans, school buses, paratransit vans and RVs built on E-series cutaway chassis and fleets who need diesel torque but no SCR/DEF/DPF nightmares. But isn’t Cummins using a 4V OHV layout for their 7-12L class engines?
The VW EA211 1.0L is a really nice engine, had one in a rental T-cross and it was plenty powerful and efficient. Ford's 1.5 3 cylinder is pretty nice as well, though not as smooth as the VW 3 popper. That said, I also think 3 cylinders sound much nicer than any 4 cylinder.
 

AP9

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It's all about generalizations, and assuming all other factors are kept constant. Of course, that's seldom if ever a valid assumption.
 
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That said, on OHC vs OHV there is ~some~ reasoning there but it mostly has to do with the fact that modern OHC engines are 4 valve per cylinder and OHV engines are 2. That lends OHV engines toward low-end torque profiles and worse breathing at high RPMs, while 4 valve per cylinders tend to have better high end pull. Rather than being inherent in OHC/OHV designs it's more inherent in the number of valves and breathing ability.
Guess it depends on where the cutoff for "modern" is. The Ford Modular's most common iteration was the 2V SOHC arrangement. Lots of SOHC Japanese engines produced too, while there were plenty of higher $$$ DOHC mills produced at the same time. Ford's recent 6.2L is a deep breathing SOHC mill (2V) and they now have a deep breathing 7.3L pushrod engine.

Ford's DOHC 4-valve V8's have, historically, not been high winding if we look at the 5.4L fitted to the Navigator for example or even the 5.0L in the F-150. Mustang's were cammed to spin a bit higher. Same with the large Japanese DOHC V8's by Toyota and Nissan.

The stock 6.4L HEMI heads flow very well (330/204 @.700 lift) but the engine isn't setup to wind with camshaft selection and it has lots of displacement.

It's typically the smaller displacement high-strung DOHC engines that are setup to wind higher, but head flow probably isn't as good as you think it is.

Honda's B16 for example, factory heads flowed 229/183 @.450. B16R flowed 259/194 @.500 lift. But, small displacement and cammed appropriately, it was a high winding engine. The Ford 4.6L 3V heads (which were not great) flowed 225/154 @.600 in comparison. Stock 4.6L DOHC Cobra heads flowed 260/201 @.550. It wasn't much of a high winder. The original LS1 heads were 231/193 @.500, also not a high winder.

While it might be obvious, I'll say it anyway, and that's for the more displacement, the more head flow you need for high RPM. The 4.6L Modular is 0.575L/cylinder, the B16 is 0.4L/cylinder and the LS1 was 0.7125L. The 6.4L HEMI is 0.8L/cylinder. So, one of the ways they kept the power up but dropped the RPM down a bit on the S2000 was to increase displacement from 2.0L to 2.2L, going from 0.5L to 0.55L.

Ford's Voodoo engine is a good example of this. 5.2L (0.65L/cylinder), making 526HP but with an 8,250RPM redline. Its heads flow over 300cfm on the intake side (no idea on the exhaust, I assume over 200). So, heads that probably flow similar to the 6.4L HEMI, but with less displacement.
 
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...
The stock 6.4L HEMI heads flow very well (330/204 @.700 lift)...
...
Dumb questions:

i) what are the two numbers, and are they in cfm's (cubic feet per min);

ii) presumably they are at atmospheric pressure (101.325 kPa) inlet?... whereas they actually in operation (naturally aspirated cases) are at a vacuum;

iii) does the flow measurement refer to such and such inches of water column across the head?; and

iv) is it that most max lift figures are 0.500"- 0.700"?

TIA
 

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Dumb questions:

i) what are the two numbers, and are they in cfm's (cubic feet per min);

ii) presumably they are at atmospheric pressure (101.325 kPa) inlet?... whereas they actually in operation (naturally aspirated cases) are at a vacuum;

iii) does the flow measurement refer to such and such inches of water column across the head?; and

iv) is it that most max lift figures are 0.500"- 0.700"?

TIA

1. Yes, that's CFM

2/3. All numbers are at 28" of water using a flow bench. Sources vary, but this is the standard method for measuring cylinder head flow. Usually the device is a SuperFlow unit. Their current offerings are found here:

4. Typically, the data presented is within the lift range typical for the application. So, you'll see different lift figures quoted for different heads. Also, the lift figure cited may not correspond with the OEM camshaft lift. The head may continue to increase flow at lift numbers well past where the OE camshaft puts things.
 
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On the topic of Ford, what was their reasoning for the 3V 4.6/5.4L V8s? Mercedes also did the same stunt in the 1990s. I know VW made a 20V 1.8T/2.0T and Toyota made a 5-valve variant of the 4A-GE.
 

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On the topic of Ford, what was their reasoning for the 3V 4.6/5.4L V8s? Mercedes also did the same stunt in the 1990s. I know VW made a 20V 1.8T/2.0T and Toyota made a 5-valve variant of the 4A-GE.
They flowed better than the 2V heads on the intake side. Guess that's an easier (more cost effective) way to increase intake flow (adding another intake valve) over adding a whole other camshaft to each bank and doing DOHC. Of course they also added troublesome phasing, lol.
 
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1. Yes, that's CFM

2/3. All numbers are at 28" of water using a flow bench. Sources vary, but this is the standard method for measuring cylinder head flow. Usually the device is a SuperFlow unit. Their current offerings are found here:

4. Typically, the data presented is within the lift range typical for the application. So, you'll see different lift figures quoted for different heads. Also, the lift figure cited may not correspond with the OEM camshaft lift. The head may continue to increase flow at lift numbers well past where the OE camshaft puts things.
Thx; I am currently researching it, have viewed several articles... but:
i) there's an intake snorkel for the cylinder head intake port that aims to reduce inlet losses evident with a sharp-edged inlet... and presumably there is a similar snorkel that starts at bore diameter of the cyl head and presumably flares out a lot... then you start with air pressure measurement in the quiescent area outside of the inlet snorkel, and you adjust it to 14.696 PSIA... one std atmosphere, and you adjust the pressure of the outlet area (in a quiescent area) to 28" WC (just about 1.0 psi) LESS than the inlet pressure... to about 13.696 PSIA... and then you measure airflow at various lift values.

Do I have this more or less correct? Test pressure (inlet) 1.0 std atmospheres, delta P across cylinder head: 1.0 psi, meas in CFM (converted to std temp and press (STP).

Haven't thought about air temps, here.

What, typically, are the two values given?
 
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