Flat crank engine
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
While I have no data on the GM FPC,
A Ferrari FPC is the same as a 4-banger:: up--down--down--up
The Ford FPC is like the Ferrari but cut at the center and one side flipped end to end:: up-down-up-down. This causes a "different" vibration pattern that apparently the Ford block was vulnerable to.
A Ferrari FPC is the same as a 4-banger:: up--down--down--up
The Ford FPC is like the Ferrari but cut at the center and one side flipped end to end:: up-down-up-down. This causes a "different" vibration pattern that apparently the Ford block was vulnerable to.
Pro
Joined: Jun 2018
Posts: 532
Likes: 104
The ford FPC was nothing but marketing hype. There are really only two advantages you get with a FPC
1. Even bank-to-bank firing. This improves exhaust scavaging and leads to a wider power band if you use equal length headers. Ford screwed this up by not using equal length headers.
2. It allows for smaller and lighter counterweights on the crank. The crank being lighter means it has a smaller moment of inertia and will rev faster. Ford screwed this up by using pretty beefy large counterweights.
The main disadvantage of a FPC on a V8 are 2nd order harmonics which will mean more vibration and fatigue on the engine.
So when you get down to it the FPC does nothing at all for Ford other than offer a marketing gimmick.
The real irony here is the 2.3L ecoboost Mustangs all have a flat plane crank too. For some reason ford didn't bother to put it "flat plane crank" on the valve covers of the 4-banger and make a big deal out of it like they did for the GT350.
1. Even bank-to-bank firing. This improves exhaust scavaging and leads to a wider power band if you use equal length headers. Ford screwed this up by not using equal length headers.
2. It allows for smaller and lighter counterweights on the crank. The crank being lighter means it has a smaller moment of inertia and will rev faster. Ford screwed this up by using pretty beefy large counterweights.
The main disadvantage of a FPC on a V8 are 2nd order harmonics which will mean more vibration and fatigue on the engine.
So when you get down to it the FPC does nothing at all for Ford other than offer a marketing gimmick.
The real irony here is the 2.3L ecoboost Mustangs all have a flat plane crank too. For some reason ford didn't bother to put it "flat plane crank" on the valve covers of the 4-banger and make a big deal out of it like they did for the GT350.
Last edited by auburn2; Jan 8, 2020 at 11:44 PM.
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
The ford FPC was nothing but marketing hype. There are really only two advantages you get with a FPC
1. Even bank-to-bank firing. This improves exhaust scavaging and leads to a wider power band if you use equal length headers. Ford screwed this up by not using equal length headers.
2. It allows for smaller and lighter counterweights on the crank. The crank being lighter means it has a smaller moment of inertia and will rev faster. Ford screwed this up by using pretty beefy large counterweights.
The main disadvantage of a FPC on a V8 are 2nd order harmonics which will mean more vibration and fatigue on the engine.
So when you get down to it the FPC does nothing at all for Ford other than offer a marketing gimmick.
The real irony here is the 2.3L ecoboost Mustangs all have a flat plane crank too. For some reason ford didn't bother to put it "flat plane crank" on the valve covers of the 4-banger and make a big deal out of it like they did for the GT350.
1. Even bank-to-bank firing. This improves exhaust scavaging and leads to a wider power band if you use equal length headers. Ford screwed this up by not using equal length headers.
2. It allows for smaller and lighter counterweights on the crank. The crank being lighter means it has a smaller moment of inertia and will rev faster. Ford screwed this up by using pretty beefy large counterweights.
The main disadvantage of a FPC on a V8 are 2nd order harmonics which will mean more vibration and fatigue on the engine.
So when you get down to it the FPC does nothing at all for Ford other than offer a marketing gimmick.
The real irony here is the 2.3L ecoboost Mustangs all have a flat plane crank too. For some reason ford didn't bother to put it "flat plane crank" on the valve covers of the 4-banger and make a big deal out of it like they did for the GT350.
For all out racing where a light rotating assembly and that improved scavenging helps at WOT, it's quite a bit of cost for relatively small improvements. So for arguments sake, say on a v8 it's worth 30 HP, I'd chase that HP elsewhere and have a smoother lower NVH engine that holds up better. Ford added so much metal back, that the rotating assembly wasn't light anymore to try and combat the NVH and paint shaker problem with a FPC
I dunno, I just don't see why they are so great for corvette. We'll see if they make it to the street. Ford isn't dumb, and they spent a crap ton of $ to finally decide the juice isn't worth the squeeze go away from the FPC on their new blown steed.
And to be blunt, those fancy ferraris sound a bit flatulent at lower rpms
Pro
Joined: Jun 2018
Posts: 532
Likes: 104
I think a good strong billet crank like those fancy windbergs hold up just fine at higher rpms. Thanks for the explanation of FPC. Road and track was trying to say that a v8 won't turbo well WITHOUT a FPC and there seems to be so much misinformation about advantages and disadvantages.
For all out racing where a light rotating assembly and that improved scavenging helps at WOT, it's quite a bit of cost for relatively small improvements. So for arguments sake, say on a v8 it's worth 30 HP, I'd chase that HP elsewhere and have a smoother lower NVH engine that holds up better. Ford added so much metal back, that the rotating assembly wasn't light anymore to try and combat the NVH and paint shaker problem with a FPC
I dunno, I just don't see why they are so great for corvette. We'll see if they make it to the street. Ford isn't dumb, and they spent a crap ton of $ to finally decide the juice isn't worth the squeeze go away from the FPC on their new blown steed.
And to be blunt, those fancy ferraris sound a bit flatulent at lower rpms
For all out racing where a light rotating assembly and that improved scavenging helps at WOT, it's quite a bit of cost for relatively small improvements. So for arguments sake, say on a v8 it's worth 30 HP, I'd chase that HP elsewhere and have a smoother lower NVH engine that holds up better. Ford added so much metal back, that the rotating assembly wasn't light anymore to try and combat the NVH and paint shaker problem with a FPC
I dunno, I just don't see why they are so great for corvette. We'll see if they make it to the street. Ford isn't dumb, and they spent a crap ton of $ to finally decide the juice isn't worth the squeeze go away from the FPC on their new blown steed.
And to be blunt, those fancy ferraris sound a bit flatulent at lower rpms
As far as racing goes, it makes sense if you have class rules limiting things like displacement or throttle body size or other things you could use to get extra hp. In that case you need to wring out everything you can out of a car within the bounds of the rules and you can't use another method to chase that power. Other than that small case I agree, no reason to have a FPC on a street car.
Drifting
Joined: Dec 2017
Posts: 1,541
Likes: 729
The flat plane will get tested and compared against its cross plane predecessor. By seasons end GM will have a pretty good idea how the two stack up under severe use conditions. Also, I hope theyve torn down a few Ford Shelby GT350 flat planes to figure out what NOT TO DO.. they are costing Ford a mint in warrantee work from what I’ve heard.
Melting Slicks
Joined: Nov 2012
Posts: 3,161
Likes: 686
From: SUFFIELD CONNECTICUT
The ford FPC was nothing but marketing hype. There are really only two advantages you get with a FPC
1. Even bank-to-bank firing. This improves exhaust scavaging and leads to a wider power band if you use equal length headers. Ford screwed this up by not using equal length headers.
2. It allows for smaller and lighter counterweights on the crank. The crank being lighter means it has a smaller moment of inertia and will rev faster. Ford screwed this up by using pretty beefy large counterweights.
The main disadvantage of a FPC on a V8 are 2nd order harmonics which will mean more vibration and fatigue on the engine.
So when you get down to it the FPC does nothing at all for Ford other than offer a marketing gimmick.
The real irony here is the 2.3L ecoboost Mustangs all have a flat plane crank too. For some reason ford didn't bother to put it "flat plane crank" on the valve covers of the 4-banger and make a big deal out of it like they did for the GT350.
1. Even bank-to-bank firing. This improves exhaust scavaging and leads to a wider power band if you use equal length headers. Ford screwed this up by not using equal length headers.
2. It allows for smaller and lighter counterweights on the crank. The crank being lighter means it has a smaller moment of inertia and will rev faster. Ford screwed this up by using pretty beefy large counterweights.
The main disadvantage of a FPC on a V8 are 2nd order harmonics which will mean more vibration and fatigue on the engine.
So when you get down to it the FPC does nothing at all for Ford other than offer a marketing gimmick.
The real irony here is the 2.3L ecoboost Mustangs all have a flat plane crank too. For some reason ford didn't bother to put it "flat plane crank" on the valve covers of the 4-banger and make a big deal out of it like they did for the GT350.
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Safety Car
Joined: Nov 2002
Posts: 4,168
Likes: 1,336
From: FLL Florida
I fell much better after our talk. Thanks.
Melting Slicks
Joined: Apr 2018
Posts: 2,666
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From: North Texas
Long list of those types of people here, I finally got tired of blocking people, I just scroll past their crap now, not worth getting worked up over and not worth spending the time to block them.
Last edited by vndkshn; Jan 14, 2020 at 11:39 AM.
Pro
Joined: Jun 2018
Posts: 532
Likes: 104
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of intertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
Pro
Joined: Jun 2018
Posts: 532
Likes: 104
. The picture of the engine bay above clearly show its not DOHC heads. The horsepower and torque numbers are never a tell under IMSA BoP rules because any type engine can be intake constricted down to the mandated max hp. Years back the Viper ran the full 8 liter displacement but the engine was breathing through a straw. At that time I wondered why Dodge wouldn't have rather destroke or sleeved the engine down to under ~6 L instead but for whatever reason they preferred to nearly suffocate their full displacement mill. I never thought the engines ran very efficiently that way.
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
The high RPM is primarily due to the valvetrain and head design, not the FPC and one of the Ford engineers that designed it even said so in an interview.
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of intertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of intertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
they abandoned flat plane cranks and I think while they are great for racing, I can find other ways to get a crap ton of reliable hp other than this extreme.
Safety Car
Joined: Nov 2002
Posts: 4,168
Likes: 1,336
From: FLL Florida
The high RPM is primarily due to the valvetrain and head design, not the FPC and one of the Ford engineers that designed it even said so in an interview.
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of inertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of inertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
Melting Slicks
Joined: Nov 2012
Posts: 3,161
Likes: 686
From: SUFFIELD CONNECTICUT
The high RPM is primarily due to the valvetrain and head design, not the FPC and one of the Ford engineers that designed it even said so in an interview.
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of intertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of intertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
Safety Car
Joined: Nov 2002
Posts: 4,168
Likes: 1,336
From: FLL Florida
Brake Mean Effective Pressure (BMEP) is the yardstick for comparing the performance of an engine of a given type to another, and for evaluating the reasonableness of performance claims or requirements.
Mercedes F1 team's latest 1.6-litre V6 turbo hybrid produces over 900 bhp and achieves more than 45 percent thermal efficiency. It can even harness heat energy in the exhaust downstream by sophisticated waste heat recovery system, thus achieving more than 50 percent efficiency!!! Toyota's new 2,8-litre diesel engine 1GD-FTV achieved an efficiency of 44%. This is considered to be the highest in the world. Class 8 tractors trailers are close to that. Diesel Electric locomotives even more. The General Electric 7HA and 9HA turbine combined cycle electrical plants are rated at over 61% efficiency.
At the end of the 2014 NASCAR Cup series season, the engines from one major NASCAR engine manufacturer were producing in the neighborhood of 880 HP at about 9000 RPM, and they operate at a max race rpm in the vicinity of 9400 rpm. By regulation, CUP engines have a maximum displacement of 358 CI (5.87 L). They must use a cast-iron 90° V8 block with a 4.500 inch bore spacing and a 90° steel crankshaft. The cylinder heads are purpose-designed and highly-developed, limited to two valves per cylinder, specific valve angles, specific port floor heights, etc.. The valves are operated by a single, block-mounted, flat-tappet camshaft (that's right, still no rollers as of 2014; switching to roller cam followers for the 2015 season) and a pushrod / rocker-arm / coil-spring valvetrain. It is further hobbled by the requirement for a single four-barrel carburetor (until 2011) The fact that, to produce 880 HP at 9000 RPM, requires 513 lb-ft of torque, for a peak-power BMEP of nearly 216 PSI (14.92 bar, torque ratio of 1.43). Peak torque for that same engine was typically about 535 lb-ft at 7800 RPM, for a peak BMEP of over 226 psi (15.6 bar, torque ratio of 1.50). Nothing is even close to that.
Mercedes F1 team's latest 1.6-litre V6 turbo hybrid produces over 900 bhp and achieves more than 45 percent thermal efficiency. It can even harness heat energy in the exhaust downstream by sophisticated waste heat recovery system, thus achieving more than 50 percent efficiency!!! Toyota's new 2,8-litre diesel engine 1GD-FTV achieved an efficiency of 44%. This is considered to be the highest in the world. Class 8 tractors trailers are close to that. Diesel Electric locomotives even more. The General Electric 7HA and 9HA turbine combined cycle electrical plants are rated at over 61% efficiency.
At the end of the 2014 NASCAR Cup series season, the engines from one major NASCAR engine manufacturer were producing in the neighborhood of 880 HP at about 9000 RPM, and they operate at a max race rpm in the vicinity of 9400 rpm. By regulation, CUP engines have a maximum displacement of 358 CI (5.87 L). They must use a cast-iron 90° V8 block with a 4.500 inch bore spacing and a 90° steel crankshaft. The cylinder heads are purpose-designed and highly-developed, limited to two valves per cylinder, specific valve angles, specific port floor heights, etc.. The valves are operated by a single, block-mounted, flat-tappet camshaft (that's right, still no rollers as of 2014; switching to roller cam followers for the 2015 season) and a pushrod / rocker-arm / coil-spring valvetrain. It is further hobbled by the requirement for a single four-barrel carburetor (until 2011) The fact that, to produce 880 HP at 9000 RPM, requires 513 lb-ft of torque, for a peak-power BMEP of nearly 216 PSI (14.92 bar, torque ratio of 1.43). Peak torque for that same engine was typically about 535 lb-ft at 7800 RPM, for a peak BMEP of over 226 psi (15.6 bar, torque ratio of 1.50). Nothing is even close to that.
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
nascar has taken the development of those engines to another level. some of the super comp guys build little buz bomb sbc and now ls motors that scream up
john lingenfelter made a name by running big bore short stroke dragsters that buzzes to 10k and makes great power. thanks for posting some really interesting info.
I'm also enamored by the top fuel guys cranking out 11k hp out of those nitro swilling monsters.
Lots of ways to make big power, vette is now able to hook it a bit better. I hope the next tremec goes with a bit taller gears to compliment the big torq
john lingenfelter made a name by running big bore short stroke dragsters that buzzes to 10k and makes great power. thanks for posting some really interesting info.
I'm also enamored by the top fuel guys cranking out 11k hp out of those nitro swilling monsters.
Lots of ways to make big power, vette is now able to hook it a bit better. I hope the next tremec goes with a bit taller gears to compliment the big torq
Safety Car
Joined: Nov 2002
Posts: 4,168
Likes: 1,336
From: FLL Florida
The high RPM is primarily due to the valvetrain and head design, not the FPC and one of the Ford engineers that designed it even said so in an interview.
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of intertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
If you look at the crank, unlike most other FPC V8s, the weights on the GT350 are not significantly smaller than a traditional crossplane crank. The lower moment of intertia normally associated with smaller counterweights on a FPC is what lets it rev quicker (not necessarily higher).
Ford designed some badass CNC ported heads for the new 5.2L, but no one’s talking about that. Ford designed the F1-inspired roller finger follower DOHC valve train that makes OE pushrod motors look stupid, but no one’s talking about that. The camshaft profiles and a variable valve-timing strategy that—when combined with the phenomenal low-lift airflow of the 5.2L’s four-valve cylinder heads enables it to produce 24% more torque per cubic inch than GM’s 7.0L LS7 (1.36 vs. 1.10), but no one’s talking about that. All of these factors play a far more substantial role in both the 5.2L’s specific output and high-rpm capability than its flat-plane crank, but no one’s talking about that.
Last edited by Shaka; Jan 18, 2020 at 10:44 AM.
Melting Slicks
Joined: Apr 2018
Posts: 2,666
Likes: 1,778
From: North Texas
And didn't Ford stray away from the standard "flat crank" design in terms of firing order? I haven't found hard evidence (such as firing order combined with Ford's cylinder numbering versus say Ferrari's), but I've read that several times. Makes me wonder if that is the reason for the issues.