Throttle Response: DE/HR vs VHR
 

So I'm not crazy after all! VVEL sounds like great technology. It offers great smoothness and consistency in power delivery especially for forced induction, and it pulls hard to redline. However, it appears the biggest tradeoff is throttle response. That's the one thing I really miss coming from the DE.

I had the opportunity to test drive my friend's '08 350Z, and he had a thrill of a test drive in my force-fed 370Z.

We started up the car and revved it in neutral. I barely touch the throttle in the 350Z, and it quickly revved to 2k as if it has a lightened flywheel. Since I'm not used to it, it feels a bit touchy on tip in. I don't think the 370Z can rev this quick. On for a test drive, I got in 1st and kept the revs under 2k. I tapped the throttle and literally broke loose before the revs touch 3k. This is with VDC disabled.

Of course, this is where it feels different. I opened it up a bit and expected more power beyond 3k. It's a slightly vague feeling over the 370Z (off boost), but there is still an immediate response of the accelerator pedal to the throttles.

It would be nice to have my ECU throttle tables tweaked to get this feeling back. It would make the 370Z (force-fed or not) so more fun to drive.

Have you heard of or read on here about a device called Sprint Booster? Some owners, even after forced induction claim that it helps to eliminate throttle lag.

IIRC that only increases the pedal sensitivity, not throttle lag?

I agree withe the OP, my old '05 DE 350Z had better throttle response. How much I'm not sure but that's one of the few things I miss from it.

Did the 350Z's have throttle by cable or by wire, like the 370's?

drive by wire

I guess that is the trade off of not actually using the throttle bodies and letting VVEL act as the throttle. Sometimes I like how progressive and smooth power delivery is but other times, it feels too relaxed and undramatic.

Fingers cross for a VVEL controller and that it could help out engine response!

Exactly. I believe UpRev makes available the throttle tables. I think "wstar" made a post about tweaking the table for better response, but it can get finicky.

It feels like our pedal simply provides inputs and the ECU determines how much it thinks the throttle position should be for efficiency, emissions, fuel economy, etc. Instead, we expect it to be 1:1.

It's almost like electric power steering. In my parent's '11 Sonata 2.0t, there's no confidence making turns because the steering feels numb and has a mind of its own.

definitely have noticed the same thing driving the 350s. I think part of it is in the way the 350 ECU responded, and the throttle tables, etc...but I think part of it is just the engine's nature. I think the VHR is just slow down low.

IIRC, the HR and VHR are very closely related. I think the difference is with the heads.

In theory you can advance the timing on tip in, which should give quicker response... I'm going to try experimenting with that next time assuming there's a table for it.

yeah, they are. The HR was notably slower than the DE too. I feel like the VHR was even slower than the HR, but it's hard to say...sometimes it is just in your head

I didn't get to push the HR hard, but it was enough to tell the difference in the lower revs. Although it ramps up slower, I can feel the power in the VHR. The HR feels like it has a lighter flywheel and is much more eager to rev. The throttle is definitely very touchy, so perhaps the VHR dampened the touchy throttle.

One thing I know for sure is that the throttle response in the DE/HR remains the same regardless of temperature even after a long drive. The VHR throttle response appears to worsen after a long day of driving.

It's the VVEL, you can feel the cams working

I feel like an LS6 swap is the cure for this throttle issue.

Wow. So wassup with the UPREV throttle tweak?

this :tiphat:

my car was just dyno tuned using Uprev from Shawn at Church automotive here in socal, AEM intakes, the Motordyne intake manifold, and Uprev tune was all done at the same time. The first thing i noticed was the much improved throttle response

Can you get clarification whether the throttle tables were modified? IIRC, Sam@GTM left the throttle table alone probably for liability reasons.

^ill ask for sure, i wasnt there during the tuning, since Dsport did the installs and took the car to get tuned

??? one main difference (besides the VVEL) between the VHR and a DE that would affect "throttle response" is plenum space... the VVEL system keeps the throttle body open and controls air with the VVEL actuator (once engine is warm and is in closed loop) and that will eliminate the "stored air" that is in a plenum... just some food for thought

I once drove a 2004.5 DE 350Z. The throttle response was............flawless.

Any solutions yet? This is something that I would like to address, but not a necessity........

wstar is currently messing with the throttle tables with his UpRev tune. One thing's for sure is that he is able to achieve 100% throttle. I don't think my tune comes with any modifications to throttle map or ability to max it out.

Interested in results. I to have noticed my 05 350z had better throttle response compared to my 370z. I'm hoping with HFC's, an exhaust and tune will cure that.

I get a warm tingly feeling knowing you guys are trying to get the most out of the 370Z...

LOL... I seriously think there are times the ECU is refusing to open up regardless of accelerator position, which won't even wake up the turbos! >.<

Theoretically the response should be greater/better with the VVEL actuating cylinder filling rather than the relatively distant throttle plates. Plenum is normally under vacuum until WOT, there would be a delay in the higher ambient pressure air making it to the valve relative to the plenum already being full with the TBs already open.

Maybe the VVEL actuator just doesn't move as quickly as a throttle plate? Comparatively, I'd imagine the VVEL mechanism has a lot more "stuff" to rotate, more mass, inertia, etc... (This is just a guess)

One of my friends was telling me the same thing. So if I floor it in 2nd from 1.5k versus 3k, there's a slight difference in how long it takes to ramp up to redline. He mentioned about the vacuum and delay.

wstar found out that disabling electronic throttle control makes it a blast to drive the car because the response is very fast, but you lose the safety features like VDC, electronic rev limiter, and S-Mode. It caused his 7AT to shift funny.

LOL Your all full of good ideas! Floor it at 1.5k and disconecting the electronic throttle control on a drive by wire car. Only a guy who has "The Bright One" on his avatar could think of such unique ideas!:roflpuke2:

I think I got your sarcasm. :icon14:

:shrug: Doesn't sound too.bad to me. I shut Vdc off everytime i get in the car, being manual with no SRM I shift before redline and know when to downshift. I'd give it a try to have the response my old DE had.

I think it was a slight misunderstanding about disabling ETC versus DBW (i.e., like disconnecting the throttle cables).

Yup... I miss kicking the tail when I tap the throttle in 1st as it quickly revs to 2k RPM. It happened when I test drove my friend's HR. :) Maybe that's too touchy of a tip in, but something close would be nice.

Yeah, that slow ramp wen you put your foot down in 1st really kills that performance feel. Guess I need to get Osiris.

*stewie voice* You... You do get the accelerator is just a couple potentiometers... right?

Yea, I know it is. Which is why I wonder about the throttle mapping and control. Disabling ETC is not referring to the accelerator pedal. It refers to the ECU control of the throttles.

I went to the sponsors section and some product (hyperrev? something like that) apparently can solve the sluggish throttle because something something about drive by wire changes how the throttle bodies behave since if you floor it blah blah it opens slower blah

I guess safety is a number one thing in general; massive response could make it very easy to break traction even at mild throttle levels of 40-70, especially once you're at the 300 wheel hp mark. Imagine instantaneous or mechanical throttle in a car with 500 wheel; instant slip and smoke.

Hence I wonder about torque management. Ever notice starting out in 1st gear at low revs with moderate throttle, and then after 1-1.5k the car accelerates harder? It's an awkward transition making it difficult to drive smoothly at times.

I noticed that in first and second gears. Seems more or less like perhaps the VVEL is adopting a different profile. I normally don't accelerate hard in first until I'm past 2k RPM, but that's just me.

That's right. I have this habit of getting the car moving at low revs so sometimes it bogs especially when it's pretty warm out.

Did a bit more reading; essentially a Cobb AccessPort, it's called HyperTech. I'm sure you've heard of it; a member did something of a review here:

Hypertech Part#62004 Review

It was pretty warm out here yesterday, drove around for the better part of two hours on both the suburban and freeway roads. Definitely felt sluggish once my oil temps hit 230, and refused to drop below 215 even on flat, steady cruises on the freeway at 60mph. It's pretty obvious that heat soak is a serious issue on Z cars. Apparently, the Hypertech does alleviate that flaccidity to some degree.

Random reading on the forums has me thinking an UPREV tune would be the easiest way to reduce the "delay" feel in 1st.

Do folks generally agree that on this or have I misinterpreted?



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