New Project - Tuning my 3.4L for POWER

[BYprodriver]

Guessing: Injectors &/or fuel pump not putting out like they should. Air induction mods are allowing too much extra heat into engine &/or engine compartment.

[insite]

Originally Posted by BYprodriver

Guessing: Injectors &/or fuel pump not putting out like they should. Air induction mods are allowing too much extra heat into engine &/or engine compartment.

good guesses; we'll see. my first thought was similar: inadequate fuel. JAAY's experience, and those of others who have done this swap, is an extreme rich condition (he was 10 to 1!!). in my case, i do see a lot of soot across the back of my bumper that gathers over time.

i wonder if the flow charicteristics of the 996 air box don't translate well to a straight-through MAF housing. on the 996, the MAF is VERY close to the airbox inlet & not entirely round.

[BYprodriver]

Originally Posted by insite

good guesses; we'll see. my first thought was similar: inadequate fuel. JAAY's experience, and those of others who have done this swap, is an extreme rich condition (he was 10 to 1!!). in my case, i do see a lot of soot across the back of my bumper that gathers over time.

i wonder if the flow charicteristics of the 996 air box don't translate well to a straight-through MAF housing. on the 996, the MAF is VERY close to the airbox inlet & not entirely round.

I recently installed 987 airbox & MAF tube with 997 plenum "T" & T/B, then reflashed with '00 LEV 996 map for my 3.6 boxster engine & it seems to work very well. Pulls to 7400 very smoothly.

[The Radium King]

variocam+ would account for some of the hp on the table vs the cayman.

but if we are not comparing to caymans but rather looking at 10:1 afrs using stock tune, then why? if the maf was consistently over-metering the air (resulting in more fuel than required) then the o2 sensors would pick up on it and adjust the fuel trims. similarily if you had leaky injectors or an over-performing fuel pump producing more fuel than expected then the 02 sensors would notice and adjust trims.

so, perhaps new o2 sensors? a quick trip to auto atlanta shows that the 986 02 sensor has a different part number that the 996; most likely due to lead length, but perhaps they are different beasts in other ways?

otherwise, the ecu will add more fuel to keep the heads cool if it is nervous about something - timing, octane, etc. - what gas are you running and is it a row or na 996 tune?

[insite]

Originally Posted by The Radium King

variocam+?

nope; i have a 3.4L from a '99. i have varioRAM (which is hooked up & functional), but only standard varioCAM.

[Topless]

A good project to investigate and a common problem on 996/Boxster conversions.

Some observations while running regularly with 3.4L Boxster conversions and 987 Cay S 3.4L:

The 987 has a nice wide, fat torque curve which allows them to put down power early on corner exit. A 996 3.4L tends to have a more narrow torque curve requiring more shifting to stay in the sweet spot. I suspect a well tuned and displacement-matched intake and exhaust along with software remapping will fatten up the torque curve and make the most out of a 996 3.4L in the Boxster.

One problem that has been reported is sonic pulses from the valve train traveling back up the intake and actually fouling the MAF sensor readings. Does the intake require a helmholtz chamber to neutralize these pulses?

[insite]

Originally Posted by Topless

One problem that has been reported is sonic pulses from the valve train traveling back up the intake and actually fouling the MAF sensor readings. Does the intake require a helmholtz chamber to neutralize these pulses?

interesting observation; i wonder if that is why there was a resonator on the original intake? anyway, i should be able to log MAF voltage vs. RPM at WOT. if there are any anomalies, i can probably program them out.

[BYprodriver]

Originally Posted by insite

nope; i have a 3.4L from a '99. i have varioRAM (which is hooked up & functional), but only standard varioCAM.

Insite is your MAF housing tube I.D. 3.5" ?

[insite]

Originally Posted by BYprodriver

Insite is your MAF housing tube I.D. 3.5" ?

yup. i use a BMC airbox w/ silicone plumbing to a 3.5" MAF housing.

[The Radium King]

996 is 3.25" ID, no? and, from what i recall about your install, your maf housing is located right after a bend?

[insite]

Originally Posted by The Radium King

996 is 3.25" ID, no? and, from what i recall about your install, your maf housing is located right after a bend?

pretty sure the 996 is 3.5".

MAF sensor should be at least 1 and ideally 1.5 pipe diameters from a bend. in this case, that would be 3.50" - 5.25". i am at the upper end of that range.

EDIT: if you look at the 996 MAF housing, the inlet is a funky shape and VERY close to the airbox itself. probably not a comparable measurement environment to the one below.