82 mm throttle body

[blue62]

Originally Posted by ike84

Hey woody, question for ya. I've been running now for a few hundred miles on this setup with 996 tune and big exhaust and I noticed that the car now likes to move! More specifically, around 4200 rpm at WOT she pushes me back in the seat, which I don't ever remember happening before. Weirdly though, it doesn't happen every time I pass 4200rom at wot. I can't quite pinpoint what is contributing to this happening (or not happening). I'm wondering if maybe the DME is still figuring stuff out.

I know most of your driving is dirt track, but I'm curious about what your experience has been so far? Big gains at high rpm? Are gains always there?

Btw, how's the shop build going?

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Ike
I have experienced the same as you in regards to the torque curve around 4200 RPM under WOT or near WOT.
Every now and then it is like there is a little more power.
My car is a 2000S completely stock.
I thought that perhaps my MAF was going bad.
Or that my resonance flapper was hanging up.
But everything checks out ok.
The car runs great.
The only thing I could come up with is:
I can only get 91 Octane fuel.
So my thought is that the DME/ECU is holding back ignition timing to prevent pre-det or knock.
I think when I feel the little bit of extra power is when the ECU/DME is allowing a little more ignition advance.
Keeping my eyes open for some higher octane fuel to test my theory.
Thoughts????

[ike84]

Originally Posted by blue62

Ike

I have experienced the same as you in regards to the torque curve around 4200 RPM under WOT or near WOT.

Every now and then it is like there is a little more power.

My car is a 2000S completely stock.

I thought that perhaps my MAF was going bad.

Or that my resonance flapper was hanging up.

But everything checks out ok.

The car runs great.

The only thing I could come up with is:

I can only get 91 Octane fuel.

So my thought is that the DME/ECU is holding back ignition timing to prevent pre-det or knock.

I think when I feel the little bit of extra power is when the ECU/DME is allowing a little more ignition advance.

Keeping my eyes open for some higher octane fuel to test my theory.

Thoughts????

Woody is right that in general the torque curves for the 2.7 and 3.2 don't start to peak until past 4k. I had never noticed the "kick" at 4200 before I did my intake and exhaust mods though. That's definitely interesting that your stock s does the same thing.

At first I wondered if it could be variocam switching over at different points depending on throttle and load but from everything I have been able to find that it always a fixed transition at 5500rpm. I posted recently about this topic but I haven't gotten any responses yet.

I have read similar comments about the timing but I'm not sure about it. I think that the base tune has ignition advanced to as early as stuttgart deemed "safe" and the only adjustments the dme will make is to pull timing if knock is detected. I've not seen any documentation that the dme will advance timing further if the fuel is higher quality. I've also not ever read that the dme will advance timing beyond the base map under specific circumstances such as wot or rpm threshold.

With that being said, you could be right that at a high enough rpm and load the timing becomes such that 91 will knock and then the timing gets retarded. I run 93 but it's the same tank that's been sitting since before I started all this work last fall, so I'll be curious to see what happens with the next fill up.

The other thing I wondered was the fuel maps in regards to open vs closed loop. Woody and I are running the 996 tune on 2.7 and 3.2 motors, respectively, and we should be encountering rich conditions when the dme flips to open loop mode. I would think that I should be so rich in open loop mode that it would probably hurt performance, where woodys probably wouldn't be effected much. I don't know of any way to actively monitor what mode the dme is running in though, unfortunately.

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[blue62]

Originally Posted by ike84

Woody is right that in general the torque curves for the 2.7 and 3.2 don't start to peak until past 4k. I had never noticed the "kick" at 4200 before I did my intake and exhaust mods though. That's definitely interesting that your stock s does the same thing.

At first I wondered if it could be variocam switching over at different points depending on throttle and load but from everything I have been able to find that it always a fixed transition at 5500rpm. I posted recently about this topic but I haven't gotten any responses yet.

I have read similar comments about the timing but I'm not sure about it. I think that the base tune has ignition advanced to as early as stuttgart deemed "safe" and the only adjustments the dme will make is to pull timing if knock is detected. I've not seen any documentation that the dme will advance timing further if the fuel is higher quality. I've also not ever read that the dme will advance timing beyond the base map under specific circumstances such as wot or rpm threshold.

With that being said, you could be right that at a high enough rpm and load the timing becomes such that 91 will knock and then the timing gets retarded. I run 93 but it's the same tank that's been sitting since before I started all this work last fall, so I'll be curious to see what happens with the next fill up.

The other thing I wondered was the fuel maps in regards to open vs closed loop. Woody and I are running the 996 tune on 2.7 and 3.2 motors, respectively, and we should be encountering rich conditions when the dme flips to open loop mode. I would think that I should be so rich in open loop mode that it would probably hurt performance, where woodys probably wouldn't be effected much. I don't know of any way to actively monitor what mode the dme is running in though, unfortunately.

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I agree that the DME is most likely set up with the most advance that is safe under the right conditions.
I wonder if timing advance in regards to Octane or rather knock is learned in a similar way as fueling maps are????
I have read that today"s knock sensors pick up pre knock that you or I would never detect.
On my OBII scanner it shows rough running feedback for each individual cyl. also ignition timing for each individual cyl. So the DME is pretty adaptable.

Since fueling maps can be learned my guess is that fueling even in open loop conditions is learned. With the narrow band O2 sensors used on these cars they are constantly going back and forth from closed to open loop. WOT, and deceleration are two examples of when they will go from closed to open loop. So it makes sense to me that fueling would be learned even in open loop conditions.
So you may or may not be running rich in open loop.
A way you can monitor this is to hook up an OBDII scanner that shows open-vs- closed loop and watch it change back and forth as you drive.
I have done it several times with my scanner.

[new986owner]

Originally Posted by ike84

Woody is right that in general the torque curves for the 2.7 and 3.2 don't start to peak until past 4k. I had never noticed the "kick" at 4200 before I did my intake and exhaust mods though. That's definitely interesting that your stock s does the same thing.

At first I wondered if it could be variocam switching over at different points depending on throttle and load but from everything I have been able to find that it always a fixed transition at 5500rpm. I posted recently about this topic but I haven't gotten any responses yet.

I have read similar comments about the timing but I'm not sure about it. I think that the base tune has ignition advanced to as early as stuttgart deemed "safe" and the only adjustments the dme will make is to pull timing if knock is detected. I've not seen any documentation that the dme will advance timing further if the fuel is higher quality. I've also not ever read that the dme will advance timing beyond the base map under specific circumstances such as wot or rpm threshold.

With that being said, you could be right that at a high enough rpm and load the timing becomes such that 91 will knock and then the timing gets retarded. I run 93 but it's the same tank that's been sitting since before I started all this work last fall, so I'll be curious to see what happens with the next fill up.

The other thing I wondered was the fuel maps in regards to open vs closed loop. Woody and I are running the 996 tune on 2.7 and 3.2 motors, respectively, and we should be encountering rich conditions when the dme flips to open loop mode. I would think that I should be so rich in open loop mode that it would probably hurt performance, where woodys probably wouldn't be effected much. I don't know of any way to actively monitor what mode the dme is running in though, unfortunately.

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Edit. Just sent Ike PM on ROW tune)

Could you kindly advise where to get a 996 ROW tune to upload to a 01 3.2? I am trying to complete the process and have the new TB, but got a cayman intake plenum which doesn’t fit. I think I need a 996 C4S plenum. Pardon my ignorance.


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[ike84]

Originally Posted by new986owner

Edit. Just sent Ike PM on ROW tune)

Could you kindly advise where to get a 996 ROW tune to upload to a 01 3.2? I am trying to complete the process and have the new TB, but got a cayman intake plenum which doesn’t fit. I think I need a 996 C4S plenum. Pardon my ignorance.


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Hey man, I just saw this post. I pm'd at the end of the week, hope you got it. Why doesn't the cayman tb fit? Good luck!

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[new986owner]

Originally Posted by ike84

Hey man, I just saw this post. I pm'd at the end of the week, hope you got it. Why doesn't the cayman tb fit? Good luck!

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Cayman Plenum lists Part number as 987.110.416.01
Unsure. As I prepare to get to this project, the 996T looks like a completely different shape than this part I have here in my hands. This Cayman part has a 30 degree bend, and ~30 degree radius off center to said bend.

I have the TB part no 997.605.115.00

And I’m confrused- I know I need silicon elbows and longer screws but don’t have the parts list handy. That problem, plus the inability to access the ROW tune led me to post. I will go check your PM now. Thank you brother. -new986owner potentially former 986owner haha


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