Boxster S M96/21 overbore to 3.6/3.8 with stock DME?

[PaulE]

My 2003 S was rebuilt as a 3.6 with LN Nickies. I have a custom Softronic tune made for the 3.2 bored to 3.6. After engine break-in, the car was run on a chassis dyno, the results were sent to Softronic and they made some further adjustments to it. My recollection is my shop said I could stay with the stock tune, but I elected to get the Softronic tune. I stayed with the stock throttle body and intake plenum, and my headers are a more restrictive since they have catalysts. If you're going to have move open headers, a 987 airbox and MAF, bigger throttle body and matching intake plenum, you'll probably want the custom tune.

[Silber]

Thanks for sharing your experience! Great to hear that Softronic will work with custom builds on their tunes. I have sent inquiries to a number of tuners, will see what they say.

Originally Posted by PaulE

If you're going to have move open headers, a 987 airbox and MAF, bigger throttle body and matching intake plenum, you'll probably want the custom tune.

Have a few mods that would influence a tune:
Cone intake
Headers w/o cats
High flow cats in rear position
Free flow muffler

Considering bigger MAF and throttle body, but since I’m using stock 5 chain 3.2 heads not sure how much gains to be had there...

Silber

[BYprodriver]

Originally Posted by Silber

Thanks for sharing your experience! Great to hear that Softronic will work with custom builds on their tunes. I have sent inquiries to a number of tuners, will see what they say.

Have a few mods that would influence a tune:
Cone intake
Headers w/o cats
High flow cats in rear position
Free flow muffler

Considering bigger MAF and throttle body, but since I’m using stock 5 chain 3.2 heads not sure how much gains to be had there...

Silber

I have a 2001 3.2 with LN 3.6 cylinders & JE pistons & lightly ported heads It will run just as good as the 3.6 in my car without touching the DME. Its for sale in the classified column.

[Silber]

Originally Posted by BYprodriver

I have a 2001 3.2 with LN 3.6 cylinders & JE pistons & lightly ported heads It will run just as good as the 3.6 in my car without touching the DME. Its for sale in the classified column.

Thanks for the offer, you are asking a very reasonable price. However, I’m leaning toward a 3.8 and have already started buying parts to build the engine myself. I enjoy engine work and am looking forward to the task as well.

Regards,

Silber

[PaulE]

Originally Posted by Silber

Thanks for sharing your experience! Great to hear that Softronic will work with custom builds on their tunes. I have sent inquiries to a number of tuners, will see what they say.



Have a few mods that would influence a tune:
Cone intake
Headers w/o cats
High flow cats in rear position
Free flow muffler

Considering bigger MAF and throttle body, but since I’m using stock 5 chain 3.2 heads not sure how much gains to be had there...

Silber

FWIW my shop recommended against the IPD Plenum and 74mm throttle body-they said they haven't seen power increases on stock engines and in some cases have seen power decreases on their dyno. I have also read comments that a larger throttle body is like putting a bigger faucet on a pipe. You get more flow opening the faucet just a little bit (part throttle), but opening up the faucet all the way (full throttle) doesn't add anything, because the pipe diameter is the limiting factor. I don't know the real answer, but I already spent more than enough so I opted not to change my throttle body or plenum. If I ever get to the point on the track where I'm using all the power I already have and need more from this car, I'll think about it.