BRZ / FR-S Boxer Engine Dyno Powerband revealed

[Levi]

I'd like to see how the drop was deleted on the EJ25.

[Dimman]

Originally Posted by WingsofWar

^ thats interesting

I have the same kinda scenario with my EJ251 (1999-2001 2.5RS engine). But its a single cam, non AVCS, oversquared engine.

vs Dual Cam, Dual AVCS, Squared engine.

There is quite a bit of difference between the EJ251 and FA20...

Yet we still see that same awkward dip.

Does the EJ20E and EJ204 and EJ254 see similar output characteristics? What about the FB20 and FB25? Id like to see them next to each other.

If the dip is manifold related then it is likely acoustics. It could be more that the manifold runner lengths are more similar (at least relative to the dip's rpm), even if the motors aren't.

But I would think that the AVCS could tune around most of it, compared to the older non-AVCS motors.

[Mr.Black]

Hi everyone, new here. This SAE paper from Toyota has a manufacture dyno chart of the 2ZZ-GE if someone would like to overlay the dyno if possible.

[WingsofWar]

Originally Posted by Dimman

If the dip is manifold related then it is likely acoustics. It could be more that the manifold runner lengths are more similar (at least relative to the dip's rpm), even if the motors aren't.

But I would think that the AVCS could tune around most of it, compared to the older non-AVCS motors.

That makes me try to visualize what the acoustics are like at the manifolds. Is it the really the length? or could it be the materials? no wait...the intake manifolds on the EJ251 are metal while FA20 are phenolic plastic.

What about the header...yeah very similar. Is it the OEM EL header causing this?

Check this out!
http://www.rs25.com/forums/f5/t48917...o-results.html
^
OBX header and a bit of tuning to smoothen out that dip quite a bit on the EJ25D.

[quik1987]

Can I get a repost of the S2000 and BRZ on the same graph?

[JohnnyR]

Maybe they'll do an access port tune for this thing. That would flatten out the rut a little bit at least.

[serialk11r]

Originally Posted by WingsofWar

That makes me try to visualize what the acoustics are like at the manifolds. Is it the really the length? or could it be the materials? no wait...the intake manifolds on the EJ251 are metal while FA20 are phenolic plastic.

What about the header...yeah very similar. Is it the OEM EL header causing this?

Check this out!
http://www.rs25.com/forums/f5/t48917...o-results.html
^
OBX header and a bit of tuning to smoothen out that dip quite a bit on the EJ25D.

It's the length that matters, because the air will pick up velocity and then as the valve shuts a wave starts to travel in the opposite direction at the speed of sound.

[Dimman]

Originally Posted by serialk11r

It's the length that matters, because the air will pick up velocity and then as the valve shuts a wave starts to travel in the opposite direction at the speed of sound.

Also transfer from the exhaust negative pulse during overlap.

[WingsofWar]

Originally Posted by serialk11r

It's the length that matters, because the air will pick up velocity and then as the valve shuts a wave starts to travel in the opposite direction at the speed of sound.

oOo you and Dim might be right. Im looking at other dyno comparisons of the EJ251 with different headers. Never really paid attention to acoustics until now.

This short OEM EL like this sees that awkward dip at 3000-4000


This longer OBX EL header smoothens out that 3k-4k dip on some dynos im looking at from other members.

[Dimman]

^ Also stock Subaru headers are connected 'wrong' based on firing order (compare with the stock FA20 on the stand). Just made for convenience.

[Deslock]

Originally Posted by bambbrose

Yes, you are

You feel torque. Horsepower is just a function of torque/rpm.

Originally Posted by Guff

No, it's torque that moves the car, and that is what you feel. Horsepower is just some complex number: (torque X 5252)/rpm. It is important, but torque is what puts you back in the seat.

Originally Posted by Longhorn248

Yup! Dynos don't measure HP, they calculate it from the torque measurements.

1. What you feel comes from force at the wheels, which comes from wheel torque.
2. Wheel torque != engine torque, though they are proportional for any given gear ratio.
3. For any given velocity, wheel torque increases if power increases (regardless of engine torque).
4. The typical dyno plot does not show wheel torque (discussed last November in the FR-S/BRZ vs. Genesis Coupe thread).

[ahausheer]

So basically Hp is an enabler of torque? Torque moves you forward and hp determines how long that torque can be applied. Off topic I know. Ill discuss elsewhere.

[serialk11r]

Basic physics, go to school :P (in jest)

[old greg]

Originally Posted by serialk11r

It's the length that matters.

That's what she said.