Dynoing the DE5

[Victorofhavoc]

I know it works out nicely on the street, but I'm "ideologically opposed" to these small turbo torque curves that peak so high so early and fall off so hard

I'm considering a turbo upgrade in the future -- probably just something moderate like the MHI upgrade -- and it feels bad / wasteful, because I don't want the extra power so much as I just want to reshape the curves.

What are you wanting to reshape? Torque or hp?

For where the car sits currently, I'd rather trade 40wtq for 10whp more 1k further down from peak right now, but that wouldn't be reasonable. Potentially with larger piping behind the turbo and a different impeller design it might be able to flatten the curve, but a lot of this is just the nature of high boost tiny engines.

Larger housing turbo will move everything to the right (increase turbo threshold), but will also add lag for off-on throttle maneuvers. If you're just straight line blasting it it would be great. If you're doing track work, it can be hugely detrimental mid corner and during throttle management.

The mhi option isn't going to give you a flatter hp curve I believe. Correct me if I'm wrong, but it sounds like you're actually wanting to "feel a big engine" from a 4cyl turbo... Like the NA cars you really have to rev out? The mhi keeps the stock housing size to keep the tq spool in roughly the same place, but flows better overall. You'll get more under the curve, but the shape of the curve won't change. If you want to move the curve to the right you need a larger housing. That said, the mhi still has more impeller, so I would expect adding 100ms or more per throttle management input at every corner for the lag. 10 corners becomes a second and then the question becomes; are you building enough speed down the straights to compensate for that time loss and imbalance mid corner? It's a very nuanced answer... Sometimes yes and sometimes no.

Sponsored

 

[ABPDE5]

What are you wanting to reshape? Torque or hp?

For where the car sits currently, I'd rather trade 40wtq for 10whp more 1k further down from peak right now, but that wouldn't be reasonable. Potentially with larger piping behind the turbo and a different impeller design it might be able to flatten the curve, but a lot of this is just the nature of high boost tiny engines.

Larger housing turbo will move everything to the right (increase turbo threshold), but will also add lag for off-on throttle maneuvers. If you're just straight line blasting it it would be great. If you're doing track work, it can be hugely detrimental mid corner and during throttle management.

The mhi option isn't going to give you a flatter hp curve I believe. Correct me if I'm wrong, but it sounds like you're actually wanting to "feel a big engine" from a 4cyl turbo... Like the NA cars you really have to rev out? The mhi keeps the stock housing size to keep the tq spool in roughly the same place, but flows better overall. You'll get more under the curve, but the shape of the curve won't change. If you want to move the curve to the right you need a larger housing. That said, the mhi still has more impeller, so I would expect adding 100ms or more per throttle management input at every corner for the lag. 10 corners becomes a second and then the question becomes; are you building enough speed down the straights to compensate for that time loss and imbalance mid corner? It's a very nuanced answer... Sometimes yes and sometimes no.

I'd just like to flatten the torque curve a bit. I know it won't ever approach the nice flat curve you get on an NA motor, but the steep falloff just makes me want to gauge my eyes out every time I see a dyno graph

I should clarify: I'm not really serious about this... just kind of entertaining the idea. The cost / benefit isn't there to support upgrading the turbo on this platform unless you are also looking to upgrade fueling, etc., imo, and that's not a direction I'm interested in taking this car -- useless to me, personally, on this platform.

I've seen some graphs with much more mild torque curves when running larger turbos for this platform. Maybe some people are just taking advantage of the increased potential area under the curve and shaving peak torque out down low via torque request? I think the RV6 is the only one that actually adds a larger housing (and I have zero interest in a turbo that large for this car).

 

[Victorofhavoc]

I'd just like to flatten the torque curve a bit. I know it won't ever approach the nice flat curve you get on an NA motor, but the steep falloff just makes me want to gauge my eyes out every time I see a dyno graph

I should clarify: I'm not really serious about this... just kind of entertaining the idea. The cost / benefit isn't there to support upgrading the turbo on this platform unless you are also looking to upgrade fueling, etc., imo, and that's not a direction I'm interested in taking this car -- useless to me, personally, on this platform.

I've seen some graphs with much more mild torque curves when running larger turbos for this platform. Maybe some people are just taking advantage of the increased potential area under the curve and shaving peak torque out down low via torque request? I think the RV6 is the only one that actually adds a larger housing (and I have zero interest in a turbo that large for this car).

Oh I see you want to keep torque up across the band. I got you. My z was like this with a flat wall of wiiiide torque band. That's what makes those cars so smooth over the limit and why people love them for drifting.

To get a flatter torque curve you could see if a tuner can reduce the punch up front and keep it flat until the 5300rpm range. The car makes so much torque anyway that fwd at this weight and balance can't make use of it until 4th gear. Tuned I can spin third on street tires shifting early. You could probably lose 50wtq and not really feel it until 4th gear.

Here's the z dyno for comparison,

 

[UWU-mancer]

Finally got 3 clean runs in to get classing done. Only showed 290whp, but that's also at 3000ft DA and 5th gear. Seems low to me since I was expecting 330whp, but I'll take it... The consistency between runs was fairly decent. It's not as clean or consistent as my NA Z engine is, but the power band is nice and wide as well as low. Running this car out to redline is not worth it from my butt feel so this is nice confirmation. I shift early to manage heat and keep torque. This result means I can run an R8 slick or a Michelin slick and still be within classing .

Thing is... I then reflashed to see what the Cobb 93 tune and oem put down, but after reflash it wouldn't let me turn off traction control again until I drove around and restarted a few times. When I got it back on the dyno and disabled vsa again it just kept hitting a rev limiter of some sort at around 4k rpm. I just don't understand why it would be fine on the custom tune now for 3 runs and then suddenly become a problem. I'll have to do some more testing...

Dude. U correct for 4th and that tq. My god.
Grats on the numbers. Very respectable.

 

[Victorofhavoc]

So I grabbed my result from my z last year (plot above) and the Integra result, then had Claude scale both on the same graph and calculate the area under the curve.

Look at the torque wall difference. Nowhere near the same peak, but nearly double the usable area of torque and power. That translates into a much more useful powerband in a motorsports scenario.

 

[ABPDE5]

So I grabbed my result from my z last year (plot above) and the Integra result, then had Claude scale both on the same graph and calculate the area under the curve.

Look at the torque wall difference. Nowhere near the same peak, but nearly double the usable area of torque and power. That translates into a much more useful powerband in a motorsports scenario.

Yep -- this is why I love NA motors... consistent torque with linear power gains / rpm just feels so good (and throttle response / induction note, etc.).

My thought is -- as someone who's just considering a change in character / power delivery and not chasing big #s -- if I was to trim the low rpm torque in pursuit of a flatter curve...
on the stock turbo, the overall torque target would end up much lower than I want (looking at your graph, I'd say average from 3-6k rpm would end up around 260-ish wtq to achieve the milder curve I'd like)
On a slightly larger turbo, given increased area under the curve, you could still target that flatter shape and retain closer to 300 wtq average across that range.
The question is: is it worth spending $2.5-3k -- and also intentionally cutting out a big chunk of potential performance -- just for a preference in dynamics? Probably not. Fun to think about, though.

Of course, given the ability to swap maps, it's not like you're stuck leaving performance on the table -- you can just choose whether to maximize output or dynamics.

Sponsored