SAE article on GT350 engine

[eighty6gt]

http://articles.sae.org/13709/

 

[Dubstep Shep]

Interesting... So apparently they solved the second order vibration issue through dampening and stiffening.

 

[tjm73]

Cool.

 

[HEMI LOL]

i don't know if id be in a hurry to throw a tune on a GT350 after reading that.

 

[Dubstep Shep]

i don't know if id be in a hurry to throw a tune on a GT350 after reading that.

I agree... I think that's one reason why they went naturally aspirated instead of forced induction.

 

[UltraKla$$ic]

i don't know if id be in a hurry to throw a tune on a GT350 after reading that.

Yep, even worse when people start throwing boost on them. Parts flying!

 

[05yellowgt]

Interesting... So apparently they solved the second order vibration issue through dampening and stiffening.

I wouldn't say solve (because the 2nd order vibrations will ALWAYS be present), they just beefed the hell out of the components they needed to so it would stand up and then put in the right amount of dampening between the motor and the chassis so that owners wouldn't complain.

 

[Budwise]

It will be very interesting watching for the first year as people start tinkering on these. Brass balls, that is all i have to say.

 

[Redline727]

It will be very interesting watching for the first year as people start tinkering on these. Brass balls, that is all i have to say.

THIS!

People like myself, that would have to force my family to live off ramen for 84 months just to buy one and then not be able to pay for fuel should not be buying one to mod it. If I were to buy one I think I would just have to enjoy as is...as unbearable as that sounds it may be for the best. Or wait a year and learn from other, richer, people's mistakes haha

 

[TGR96]

Cool article.

I was not aware of this: "Other challenges with flat-plane-crank engines include their tendency to deliver underwhelming torque."

That's kind of a bummer. But I'd still rock a stock GT350 and be perfectly happy. I bet the noise it makes would make me forget about the torque issue.

 

[Dubstep Shep]

Cool article.

I was not aware of this: "Other challenges with flat-plane-crank engines include their tendency to deliver underwhelming torque."

That's kind of a bummer. But I'd still rock a stock GT350 and be perfectly happy. I bet the noise it makes would make me forget about the torque issue.

I really don't understand that...

Technically, the motor should deliver the same amount of torque whether it's a flat plane or a cross plane. All the flat plane does is get rid of the counterweights on the crank and even the firing order out side to side.

 

[05yellowgt]

I big part about FPC motors being "low on torque" is due to their low relative displacement. a 5.2 FPC V8 is pretty much unheard of in modern times and the motor should make good torque for the RPM band the engine is designed to operate in.

 

[Redline727]

I really don't understand that...

Technically, the motor should deliver the same amount of torque whether it's a flat plane or a cross plane. All the flat plane does is get rid of the counterweights on the crank and even the firing order out side to side.

The way I read it he was comparing it to the outgoing GT500. That's why it was stated it as "underwhelming", comparatively to the trinity motor. That's why they increased the displacement to get over 400 foot pounds.

"Other challenges with*flat-plane-crank engines include their tendency to deliver underwhelming torque.*Nair admitted that the GT350 “doesn’t have that electric-motor feel off idle that the GT500 has” but the latter also uses a blown 5.8-L rated at 631 lb·ft/855 N·m. Increasing cylinder displacement (via larger bore)*to 5.2-L,*which is 700-cc larger than Ferrari's V8 used in the 458, helped overcome some of the torque deficit."

I think the lower torque comes by design of FPC engines because of the smaller displacement due to keeping NVH down. The trade off is a better breathing, higher revving engine, that feels like it rotates more freely. But I'm sure they didn't want to put the car out with the same or less torque then the coyote.
Sent using Tapatalk

 

[Dubstep Shep]

The way I read it he was comparing it to the outgoing GT500. That's why it was stated it as "underwhelming", comparatively to the trinity motor. That's why they increased the displacement to get over 400 foot pounds.

"Other challenges with*flat-plane-crank engines include their tendency to deliver underwhelming torque.*Nair admitted that the GT350 “doesn’t have that electric-motor feel off idle that the GT500 has” but the latter also uses a blown 5.8-L rated at 631 lb·ft/855 N·m. Increasing cylinder displacement (via larger bore)*to 5.2-L,*which is 700-cc larger than Ferrari's V8 used in the 458, helped overcome some of the torque deficit."

I think the lower torque comes by design of FPC endings because of the smaller displacement due to keeping NVH down. The trade off is a better breathing, higher revving engine, that feels like it rotates more freely. But I'm sure they didn't want to put the car out with the same or less torque then the coyote.
Sent using Tapatalk

Ah I didn't realize they were comparing it to the GT500. Of course it's going to feel like it has less torque than that...

 

[Racer47]

Interesting... So apparently they solved the second order vibration issue through dampening and stiffening.

Did they make it wet?

 

[claudermilk]

Ah I didn't realize they were comparing it to the GT500. Of course it's going to feel like it has less torque than that...

Which seems silly to me. GT500 is made for huge torque, 1/4 mile & nutswinging. GT350 is made for corner carving. Different purposes.

That said, it will be interesting to watch those with more money than they know what to do with tinker with these & find the failure points.

 

[kytoploader]

I wouldn't modify one.

 

[Sky Render]

i don't know if id be in a hurry to throw a tune on a GT350 after reading that.

I'm not entirely sure where this comment is coming from. The only mention of "tuning" in the article was this:

'What followed was, in Nair’s words, “a lot of stiffening of the cylinder block, exhaust system, and various brackets” achieved through an intense FEA analysis, plus “a lot of tuning.” Nair said the result yielded unique torsional-damping technology among other patent-pending actions aimed at taming the beast.'

That "tuning" doesn't necessarily mean ECU tuning. In fact, I believe he's referring to chassis tuning, specifically engine mounts and dampers.

 

[cdynaco]

I really don't understand that...

Technically, the motor should deliver the same amount of torque whether it's a flat plane or a cross plane. All the flat plane does is get rid of the counterweights on the crank and even the firing order out side to side.

I think this has application:

The Cross-plane Crank

(2008?) So Yamaha’s new R1 has a cross-plane crankshaft: what’s that all about?

To understand it, first imagine a crankshaft on its own, no pistons or conrods, spinning in friction-free bearings. There’s nothing to slow it down or speed it up so it just keeps spinning at a smooth, constant speed. Now attach the conrods and pistons, and for the sake of this mind experiment, we’ll make them friction-free too, so you can spin the crank again and the pistons bob up and down, and the whole system keeps on rotating and reciprocating. At this stage there’s no combustion or valve gear or anything to confuse the issue, and crucially, there is no energy being put into our system and none being extracted or lost. This matters because it is a fundamental law of the universe that energy cannot be created or destroyed, only converted into another form – physicists know this as the first law of thermodynamics.

Within this system, the pistons are travelling at high speed when they’re half way along their cylinders, and at this point they have a lot of kinetic energy. Yet 90 degrees of crankshaft rotation later, all four pistons are stationary, two at the top, two at the bottom. Their kinetic energy hasn’t simply vanished because it can’t: instead it’s been transferred to the crankshaft, which was responsible for slowing the pistons down. As a result, the crank itself has increased its speed. Another 90 degrees on and the pistons are back up to maximum speed, accelerated by the crank which has returned some energy to them and in turn, it’s slowed down again.

In a full rotation the crank will have sped up and slowed down twice, generating rapid negative and positive torque pulses completely independent of the torque produced by the combustion. This constant pulsing torque is like a background noise to the main torque output, blurring its edges and taking away a small element of rider control and precision as he tries to hold the back tyre on the very edge of its grip.

On Yamaha’s cross-plane crankshaft, these fluctuations are all but eliminated. In this layout the crankpins are distributed at 90 degrees to each other around the crankshaft (in two planes which form a cross). So as one piston is slowing down and losing energy to the crank, another is speeding up and taking the same amount back. At no point do all the pistons stop together, as they do on a flat-plane crank. Instead the energy flow is evened out and the rotation of the crank is almost completely smooth and steady.
http://ashonbikes.com/cross-plane_crank

 

[lito]

This affect basically how torque is delivered, which would affect motorcycle traction hence its importance in this application, not total torque.