A visual example of the 90 degree crank drawback.

[Tom68]

5 and 7.jpg

[SchmidtMotorWorks]

As someone that like things to be orderly and sound smooth I liked the idea of flat crank V8s before ever working on one.

Then when I went to work at HPD on the Indy engine, they had both flat and 90 degree cranks.
I was disappointed to see that the power differences were not what one might expect.
In some ways better, in some ways worse.

Vibration, the flat crank was worse.

When I worked at Bryants crankshafts, in the early years, we were the first company that could make a really good billet crank. Racers from Pro Stock, NASCAR, Nitro etc all tried flat cranks, very few tried more than 1.

[englertracing]

As someone that like things to be orderly and sound smooth I liked the idea of flat crank V8s before ever working on one.

Then when I went to work at HPD on the Indy engine, they had both flat and 90 degree cranks.
I was disappointed to see that the power differences were not what one might expect.
In some ways better, in some ways worse.

Vibration, the flat crank was worse.

When I worked at Bryants crankshafts, in the early years, we were the first company that could make a really good billet crank. Racers from Pro Stock, NASCAR, Nitro etc all tried flat cranks, very few tried more than 1.

Wish there was some videos of those tests

[juuhanaa]

So there should be some cheap wrong cranks for hot rodders to buy now.

[BCjohnny]

As with a lot of things automotive, the flat plane vs cross plane issue is another compromise ......

Smaller capacity V8s, predominantly those racing in the tighter regulated formulae where winning is down to the last 'enth', will almost always be 'flat'

Larger capacity V8s, where the rules are looser and there is generally more variety, will usually be 'cross'

And it's mostly a vibration thing ...... even Cosworth struggled with it in the early days with their puny little 3 litres pulling eight grand ...... particularly the very destructive out of imbalance, twice engine speed, secondary harmonic

[Tom68]

As someone that like things to be orderly and sound smooth I liked the idea of flat crank V8s before ever working on one.

Then when I went to work at HPD on the Indy engine, they had both flat and 90 degree cranks.
I was disappointed to see that the power differences were not what one might expect.
In some ways better, in some ways worse.

Vibration, the flat crank was worse.

When I worked at Bryants crankshafts, in the early years, we were the first company that could make a really good billet crank. Racers from Pro Stock, NASCAR, Nitro etc all tried flat cranks, very few tried more than 1.

Yer flat 8 cranks for flat 8 motors, at least then they can run some stroke length.
Although the flat 8's do sound....well...a bit flat.

[SchmidtMotorWorks]

Wish there was some videos of those tests

Honda is very secretive, and high security, during the hiring process I was never allowed to see the shop until my first day at work.

If you like engine dyno video of guys testing things with hope and cheer when there are good results, and "let's try this or that", you would be disappointed, it is nothing like that.

The dyno operators run double-blind tests, they execute a test plan and record the data, they are not informed of what change they are testing, as that could influence the process. Engineers were not allowed to go near the dyno rooms to avoid guesses by the operators about what was being tested.

[hoffman900]

Here is a good visualization of an 90* crank in the intake manifold with a common plenum:
https://www.facebook.com/watch/?v=303159527677911
(Converge CFD model from Roush-Yates)

I know the GM Engineers working on the IMSA / WEC / FIA Corvette C8R like the flat-plane crank because it pulls more evenly on the restrictors. They have BOP issues, but if they can fatten up things under the curve and make the BSFC better, it helps them in endurance racing.

[englertracing]

Wish there was some videos of those tests

Honda is very secretive, and high security, during the hiring process I was never allowed to see the shop until my first day at work.

If you like engine dyno video of guys testing things with hope and cheer when there are good results, and "let's try this or that", you would be disappointed, it is nothing like that.

The dyno operators run double-blind tests, they execute a test plan and record the data, they are not informed of what change they are testing, as that could influence the process. Engineers were not allowed to go near the dyno rooms to avoid guesses by the operators about what was being tested.

Well I mean a flat plane cup motor or, prostock or top fuel.
I'm sure the prostock and fuel guys made passes especially since the fuel guys aren't dynoing.

[juuhanaa]

As with a lot of things automotive, the flat plane vs cross plane issue is another compromise ......

Smaller capacity V8s, predominantly those racing in the tighter regulated formulae where winning is down to the last 'enth', will almost always be 'flat'

Larger capacity V8s, where the rules are looser and there is generally more variety, will usually be 'cross'

And it's mostly a vibration thing ...... even Cosworth struggled with it in the early days with their puny little 3 litres pulling eight grand ...... particularly the very destructive out of imbalance, twice engine speed, secondary harmonic

I can tell some tips how to reduce weight from rotatin assembly It follows the cylinder head porting process, i mean the hole process not flow numbers

Port and polish

[SchmidtMotorWorks]

Honda is very secretive, and high security, during the hiring process I was never allowed to see the shop until my first day at work.

If you like engine dyno video of guys testing things with hope and cheer when there are good results, and "let's try this or that", you would be disappointed, it is nothing like that.

The dyno operators run double-blind tests, they execute a test plan and record the data, they are not informed of what change they are testing, as that could influence the process. Engineers were not allowed to go near the dyno rooms to avoid guesses by the operators about what was being tested.

Well I mean a flat plane cup motor or, prostock or top fuel.
I'm sure the prostock and fuel guys made passes especially since the fuel guys aren't dynoing.
[/quote]

I guess there were only about 20 made in the 4 years I was there.
Those were the first 4 years, there were probably more after that.
I don't know if that kind of stuff gets sold on eBay or not.

I know of one nitro team that dyno tested.

[ptuomov]

So there should be some cheap wrong cranks for hot rodders to buy now.

They probably didn't abandon the idea because the "NVH concerns", it was a more "concrete" downside.

[ptuomov]

Wish there was some videos of those tests

Honda is very secretive, and high security, during the hiring process I was never allowed to see the shop until my first day at work.

If you like engine dyno video of guys testing things with hope and cheer when there are good results, and "let's try this or that", you would be disappointed, it is nothing like that.

The dyno operators run double-blind tests, they execute a test plan and record the data, they are not informed of what change they are testing, as that could influence the process. Engineers were not allowed to go near the dyno rooms to avoid guesses by the operators about what was being tested.

You must have loved it them doing it right.

[SchmidtMotorWorks]

They probably didn't abandon the idea because the "NVH concerns", it was a more "concrete" downside.

In the case of the IHRA Pro Stock applications which had strokes around 5.0 at the time, they were undrivable because of vibration.

[Tom68]

They probably didn't abandon the idea because the "NVH concerns", it was a more "concrete" downside.

In the case of the IHRA Pro Stock applications which had strokes around 5.0 at the time, they were undrivable because of vibration.

Wow, I guess they had to try it, but anything over a pissant capacity that is being used in a weight sensitive environment is always going to be a disaster.