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-   -   Why does it feel slower at WOT than at partial throttle? (https://www.miataturbo.net/engine-performance-56/why-does-feel-slower-wot-than-partial-throttle-78691/)

buffon01 04-25-2014 02:34 AM

Why does it feel slower at WOT than at partial throttle?
 
I've been curious about this feeling for some time. My car seems to accelerate slower under WOT than under partial throttle. I've searched for the similar issues but only found a related topic with e90 BMWs. Any clue what may be going on?

Braineack 04-25-2014 08:11 AM

placebo effect.

Full_Tilt_Boogie 04-25-2014 09:02 AM

Faster? Or spooling faster?

Ive noticed that rolling into the throttle seems to make a turbo spool a little faster than just punching it. More noticeable with extra big ass turbos like Hondas tend to run.

Sparetire 04-25-2014 12:27 PM

^ Yep. And some tiny turbos get awesome surge issues along the same lines.

Also, check your throttle linkage.

And your maps vs data logs, Seen maps with a timing drop at a certain MAP/IAT that often roughly corresponds to WOT vs 80% throttle. If cold weather tends to move that 'optimal throttle point' lower, then you may have your culprit.

buffon01 04-25-2014 12:41 PM


Originally Posted by Braineack (Post 1125221)
placebo effect.

Could all this is based on buttdyno data. However, the car use to feel much more alive before. Or maybe I got used to it


Originally Posted by Full_Tilt_Boogie (Post 1125235)
Faster? Or spooling faster?

Ive noticed that rolling into the throttle seems to make a turbo spool a little faster than just punching it. More noticeable with extra big ass turbos like Hondas tend to run.

I don't have any data with regards to spool. It just feels that the power delivery is faster. My churbo could be be consider somewhat big. 2871-ish journal.


Originally Posted by Sparetire (Post 1125345)
^ Yep. And some tiny turbos get awesome surge issues along the same lines.

Also, check your throttle linkage.

And your maps vs data logs, Seen maps with a timing drop at a certain MAP/IAT that often roughly corresponds to WOT vs 80% throttle. If cold weather tends to move that 'optimal throttle point' lower, then you may have your culprit.

Timing seems fairly constant and matches with the values I have in my spark table.

y8s 04-25-2014 01:05 PM

I can think of some reasons part throttle feels faster:

1. better tuning at lower TPS. (Richness isn't conducive to power)
2. increased intake flow velocity from throttling the airway leads to better mixing which could lead to better torque

18psi 04-25-2014 01:08 PM

what does your spark and fuel map look like at part throttle vs full? leaner + tons of timing = faster

buffon01 04-25-2014 01:28 PM

4 Attachment(s)
This is what I have now. Spark and fuel seem very constant. However, this is at WOT and I don't have anything for partial.

18psi 04-25-2014 01:34 PM

there is a drastic difference in timing

also are you using an mbc?

buffon01 04-25-2014 01:51 PM


Originally Posted by 18psi (Post 1125433)
there is a drastic difference in timing

also are you using an mbc?

Drastic from lower kpa to higher kpa or the actual read from the log vs map input?

No mbc it's all wastegate.

18psi 04-25-2014 01:57 PM

your map is triggering a difference of 5* between part throttle and wot.

Savington 04-25-2014 02:41 PM

Your fuel map is a mess, dude.

buffon01 04-25-2014 02:50 PM


Originally Posted by Savington (Post 1125472)
Your fuel map is a mess, dude.

Agreed. I am in the process of changing a few key components on my set up so tuning is going to have to wait for now.

Braineack 04-25-2014 05:13 PM


Originally Posted by buffon01 (Post 1125357)
Could all this is based on buttdyno data. However, the car use to feel much more alive before. Or maybe I got used to it


no it's more like: if you're at 200kPa at 50% throttle, and 200kPa at 100% throttle is a difference in regards to engine load?


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