SBC Flat Plane
Thread Starter
Melting Slicks
Joined: Feb 2003
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From: Saskatoon Sask.
SBC Flat Plane
After reading another thread where the OP said he likes the sound of the new Mustang, I got to thinking. Did anyone ever develop a flat plane crank for the Gen 1 350? I see a couple of old articles where they claim one was "in development" but I don't see any info on if this ever came about. I may have missed it but I don't recall this ever being discussed here.
Le Mans Master
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From: New Jersey
I recall this coming up last year sometime and there was a lone video of someone having basically a "barn find" of a true 180 degree one off chevy small block. I'm going to look for the thread and link it if I find it.
Edit: found the
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Edit: found the
Last edited by 84 4+3; May 3, 2021 at 09:29 PM.
Team Owner
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From: Park City Utah
Yes, they've made flat plane cranks for SBC's. I have a few things to say about this b/c I find the current lust for flat plane cranks to be a bit annoying. (Not saying that you have a fetish for flat cranks, but many do).
In fact, Summit Racing has a SMOKIN' deal on one today!
Sounds like a typical 4 banger, to me....
Sounds like an air cooled, 80's 4 cylinder *** bike engine...
The sound of the Mustang with the flat crank, was engineered to sound good....and in doing so, Ford eliminated the one primary advantage that the single plane crank offers; even firing pulses on each engine side, and thus, perfect exhaust tuning with equal length headers. Likely, the GT350 sounded like a 4 cylinder poo with equal length primary tubes (as most all flat plane V8's do) so they change the primary tube length to get better sound...thus side stepping the tuning potential of the exhaust for that application.
You could get the same potential benefits (and awesome flat plane sound) by using (buying or building) equal length, 360° headers on any typical 90° crank V8. The result will be the same; 180° firing pulses coming out of each collector, and a sound much like that of an in-line 4 cylinder.
The only other benefit of the flat crank is it's lower mass and thus rotating inertia, which obviously "helps it rev more quickly". But how significant is this improvement? Minuscule to non existent. You could achieve much larger rotating mass reduction in the flywheel and clutch assy for way less money.
In fact, Summit Racing has a SMOKIN' deal on one today!
Sounds like a typical 4 banger, to me....
Sounds like an air cooled, 80's 4 cylinder *** bike engine...
The only other benefit of the flat crank is it's lower mass and thus rotating inertia, which obviously "helps it rev more quickly". But how significant is this improvement? Minuscule to non existent. You could achieve much larger rotating mass reduction in the flywheel and clutch assy for way less money.
Race Director
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From: Melbourne, FL
Not to belabor the point, but that lower rotating mass also allows for a rotating assembly to spin to a higher rpm without adding a lot more expense. That's why Ford used it for the gt350. Well, that and marketing. It's worth a lot more in marketing than outright performance... Still a gt350 is a very cool car lol.
Team Owner
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From: Park City Utah
Le Mans Master
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From: New Jersey
It's a cool design and has it's place. I don't fault people for liking it but in the average street car you don't really take advantage of its strengths. It's just cool to say you have one and if you like the sound it's cool too.
Race Director
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From: Melbourne, FL
I'm far from an engine designer, but my understanding was just that it reduced the rotational mass, thereby allowing it to Rev higher assuming the same balancing was done. Essentially just that the lower rotating mass took less energy to spin. Thinking about it now, that makes no sense, as the engine would have more than enough power to spin the crank as fast as needed.
Team Owner
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From: Park City Utah
Agreed. It's like saying that a heavy car won't have as high a top speed as a light car (all else equal/same). They'll both have the same top speed, but the light one can accelerate faster to the same top speed.
The flat crank offers a similar benefit...unfortunately the real benefit is very, small as compared to the mass and diameter of the flywheel and clutch.
The flat crank offers a similar benefit...unfortunately the real benefit is very, small as compared to the mass and diameter of the flywheel and clutch.
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Thread Starter
Melting Slicks
Joined: Feb 2003
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From: Saskatoon Sask.
Agreed. It's like saying that a heavy car won't have as high a top speed as a light car (all else equal/same). They'll both have the same top speed, but the light one can accelerate faster to the same top speed.
The flat crank offers a similar benefit...unfortunately the real benefit is very, small as compared to the mass and diameter of the flywheel and clutch.
The flat crank offers a similar benefit...unfortunately the real benefit is very, small as compared to the mass and diameter of the flywheel and clutch.
Burning Brakes
Joined: Nov 2000
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A bunch of real world stuff has to be ignored... Air resistance... Rolling resistance... Etc... But the theory is right.
As far as a flat plane just being marketing? No g*dd*mn*d way.
GM is, by all indications, about to spin a motor to the moon in the upcoming Z06 and they don't screw around... Getting GM to move away from OHV motors still hasn't happened because they make good engineering sense in spite of every idiot auto journalist calling them dinosaurs for it... There is no way on Earth they would go flat plane merely for marketing.
Last edited by PacerX; May 4, 2021 at 12:11 PM.
Team Owner
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From: Park City Utah
"It's like saying that a heavy car won't have as high a top speed as a light car (all else equal/same)"
So we're talking the same car "all else equal/same"...but different weights. Same shape, body, aero, engine, ride height, but different weights...they'll go the same speed.
Team Owner
Joined: Aug 2004
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From: Park City Utah
Oh yeah?
Remember before the C8/mid engine was official? Remember what GM/Chevy's position was on the front/mid engine car?
What was that? Were they building a front/mid car b/c it really was better? It was ALL marketing. They told us one thing for the C5/6/7...then they built the C8.
People know Ferrari and other "exotics" have flat cranks. People know that race cars have flat plane cranks. People don't exactly understand WHY they do, but they have 'em, so they're better. There is for SURE, marketing equity in that and Ford exploited the **** out if it w/the GT350....the negated the actual benefits with the exhaust that they put on it.
EDIT: Did you know that the first production V8's all had flat plane cranks? Why?
"Most early V8 road car engines also used a flat-plane crankshaft, since this was simpler to design and build than a cross-plane crankshaft. Early flat-plane V8 engines included the 1910 De Dion-Bouton engine, the 1915 Peerless engine, and the 1915 Cadillac engine."
.
Remember before the C8/mid engine was official? Remember what GM/Chevy's position was on the front/mid engine car?
What was that? Were they building a front/mid car b/c it really was better? It was ALL marketing.
They told us one thing for the C5/6/7...then they built the C8.People know Ferrari and other "exotics" have flat cranks. People know that race cars have flat plane cranks. People don't exactly understand WHY they do, but they have 'em, so they're better. There is for SURE, marketing equity in that and Ford exploited the **** out if it w/the GT350....the negated the actual benefits with the exhaust that they put on it.
EDIT: Did you know that the first production V8's all had flat plane cranks? Why?
"Most early V8 road car engines also used a flat-plane crankshaft, since this was simpler to design and build than a cross-plane crankshaft. Early flat-plane V8 engines included the 1910 De Dion-Bouton engine, the 1915 Peerless engine, and the 1915 Cadillac engine."
.
Last edited by Tom400CFI; May 4, 2021 at 12:29 PM.
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,657
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From: Saskatoon Sask.
No. I said:
"It's like saying that a heavy car won't have as high a top speed as a light car (all else equal/same)"
So we're talking the same car "all else equal/same"...but different weights. Same shape, body, aero, engine, ride height, but different weights...they'll go the same speed.
"It's like saying that a heavy car won't have as high a top speed as a light car (all else equal/same)"
So we're talking the same car "all else equal/same"...but different weights. Same shape, body, aero, engine, ride height, but different weights...they'll go the same speed.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
There is a reason. They go around turns. They aren't going flat out, straight line, to the car's absolute, drag limited, top speed.
Come on man...this is pretty basic physics here. Weight doesn't affect top speed. It affects acceleration.
.
Come on man...this is pretty basic physics here. Weight doesn't affect top speed. It affects acceleration.
.
Last edited by Tom400CFI; May 4, 2021 at 12:32 PM.
Race Director
Joined: Oct 2012
Posts: 17,275
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From: Melbourne, FL
No. I said:
"It's like saying that a heavy car won't have as high a top speed as a light car (all else equal/same)"
So we're talking the same car "all else equal/same"...but different weights. Same shape, body, aero, engine, ride height, but different weights...they'll go the same speed.
"It's like saying that a heavy car won't have as high a top speed as a light car (all else equal/same)"
So we're talking the same car "all else equal/same"...but different weights. Same shape, body, aero, engine, ride height, but different weights...they'll go the same speed.
Race Director
Joined: Oct 2012
Posts: 17,275
Likes: 6,469
From: Melbourne, FL
Oh yeah?
Remember before the C8/mid engine was official? Remember what GM/Chevy's position was on the front/mid engine car?
What was that? Were they building a front/mid car b/c it really was better? It was ALL marketing. They told us one thing for the C5/6/7...then they built the C8.
People know Ferrari and other "exotics" have flat cranks. People know that race cars have flat plane cranks. People don't exactly understand WHY they do, but they have 'em, so they're better. There is for SURE, marketing equity in that and Ford exploited the **** out if it w/the GT350....the negated the actual benefits with the exhaust that they put on it.
EDIT: Did you know that the first production V8's all had flat plane cranks? Why?
"Most early V8 road car engines also used a flat-plane crankshaft, since this was simpler to design and build than a cross-plane crankshaft. Early flat-plane V8 engines included the 1910 De Dion-Bouton engine, the 1915 Peerless engine, and the 1915 Cadillac engine."
.
Remember before the C8/mid engine was official? Remember what GM/Chevy's position was on the front/mid engine car?
What was that? Were they building a front/mid car b/c it really was better? It was ALL marketing.
They told us one thing for the C5/6/7...then they built the C8.People know Ferrari and other "exotics" have flat cranks. People know that race cars have flat plane cranks. People don't exactly understand WHY they do, but they have 'em, so they're better. There is for SURE, marketing equity in that and Ford exploited the **** out if it w/the GT350....the negated the actual benefits with the exhaust that they put on it.
EDIT: Did you know that the first production V8's all had flat plane cranks? Why?
"Most early V8 road car engines also used a flat-plane crankshaft, since this was simpler to design and build than a cross-plane crankshaft. Early flat-plane V8 engines included the 1910 De Dion-Bouton engine, the 1915 Peerless engine, and the 1915 Cadillac engine."
.
GM went midengine for marketing, so they could try to go after the guys who could almost afford the exotics, but not really, and so the retiring 401k cash outs could tell themselves they made it and bought a mid engine supercar before they die. That's the only logical conclusion. If they did it for performance, then their whole engineering team should be fired, because they failed after a massive investment.
Thread Starter
Melting Slicks
Joined: Feb 2003
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From: Saskatoon Sask.
Team Owner
Joined: Aug 2004
Posts: 21,543
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From: Park City Utah
GM went midengine for marketing, so they could try to go after the guys who could almost afford the exotics, but not really, and so the retiring 401k cash outs could tell themselves they made it and bought a mid engine supercar before they die. That's the only logical conclusion. If they did it for performance, then their whole engineering team should be fired, because they failed after a massive investment.
Now they're going to sell "sick bastard", exotic tech flat plane cranks to fan-folks. People are already bought in...even if there aren't meaningful real world advantages.
Team Owner
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From: Park City Utah
Le Mans Master
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For flat plane cranks, please see the attached picture from "The Design and Tuning of Competition Engines" by Philip H. Smith (6th Edition). This might help some of the discussion.
Last edited by bb62; May 4, 2021 at 03:43 PM.