3.2 swap into a 99...some questions

[Quadcammer]

Gents,
My 2.5L motor is kaput with about 90psi hot/35psi cold in hole 3. I have a line on a low mile 3.2 from a 00 Box S.

My research has revealed the following:

1. I will need a cable operated 3.4L 996 throttle body
2. I will need to add wiring to the dme to run the varioram changeover solenoid
3. I will need to use my current 5 speed flywheel.
4. I will need to have my Bosch 5.2 DME software changed from 2.5 to 3.4L, which should work fine with the 3.2

Now my questions:

1. Will the 3.4 throttle body fit my 2.5 crossover tube and will that in turn fit the 3.2 plenums? If not, will I need to use a 996 (99 model year) crossover tube? Will that fit the plenums?

2. I have fabspeed race headers on my 2.5. Will they fit the 3.2?

3. Can I use the stock 2.5 MAF? If not, what replacement is necessary?

4. Intake tube. Is the spectre flexy hose the best option or is there a better choice for this setup?

Thanks for any help you guys can provide.

[Quadcammer]

seems I answered my own question about the crossover tube

[j.fro]

1. I will need a cable operated 3.4L 996 throttle body
2. I will need to add wiring to the dme to run the varioram changeover solenoid
3. I will need to use my current 5 speed flywheel.
4. I will need to have my Bosch 5.2 DME software changed from 2.5 to 3.4L, which should work fine with the 3.2

Both the 2.5 and 3.4 used the same MAF (996-606-124-00), but in different diameter housings. If you go to a 3.4 flash, you'll need a larger MAF housing to get your AFR's right.

Now my questions:

1. Will the 3.4 throttle body fit my 2.5 crossover tube and will that in turn fit the 3.2 plenums? If not, will I need to use a 996 (99 model year) crossover tube? Will that fit the plenums?


The 3.4 TB will not fit the 2.5 intake. The 3.2 stock TB is 68mm. The 3.4 is 74 MM. If your 2.5 has a 68mm TB, then you should be good with that, but... the 74mm TB will add some power.

2. I have fabspeed race headers on my 2.5. Will they fit the 3.2? The bolt pattern fits but I believe the diameter is a bit smaller. I know the cat pipe diameters are smaller.

3. Can I use the stock 2.5 MAF? If not, what replacement is necessary?
The airbox did not change, so that should work.

4. Intake tube. Is the spectre flexy hose the best option or is there a better choice for this setup?
build your own intake from solid plastic tubing. Airaid UBI Custom Intake Systems & Components | JEGS

Thanks for any help you guys can provide.[/QUOTE]

[Quadcammer]

Thanks for the info. Just to get things straight

When you say the 74mm won't fit the stock intake, do you mean the curved intake tube, or the intake crossover. In looking at PET, it appears that both the 3.4 996 (cable) and the 986 2.5 use the 996 110 215 53 "intermediate piece".

2. Fabspeed told me the difference from 97-99 and 00-04 is the cat location. I don't believe there is a difference in the primaries. Maybe there is and the 2.5 units are not ideal, but I think they will be sufficient.

3. I'm now confused about the maf. I acknowledge that I can use the stock maf, but to run the 3.4 tune I need the 996 sample tube, which I don't believe would fit the airbox. Would I need to run the "insite style" intake tube which uses a 540i bmw sample tube halfway up the intake tube?

Thanks again.

[Quadcammer]

With respect to intake, i think the best plan is to cut off the 986 maf tube about half an inch after it comes out of the airbox, use a 3 to 3.5" adapter shortened as much as possible, the 3.5" maf housing with oem sensor, then a 90 degree turn and straight shot to throttle body. That should put the maf in as close to the stock position

[soccerties]

For my 3.4 swap I used a 987 air box and maf housing. The maf housing is smaller than the 3.4 tune expects but it seems to be within tolerance for it to adjust. The only custom intake tubing you'd need is from the maf housing to the throttle body. Makes for a clean stock fit/look and provides ample air flow for the larger engine.

Here's a good thread on the details.
987 v 986 Air box

[j.fro]

When you say the 74mm won't fit the stock intake, do you mean the curved intake tube, or the intake crossover. In looking at PET, it appears that both the 3.4 996 (cable) and the 986 2.5 use the 996 110 215 53 "intermediate piece".

I mean the tube that the TB bolts onto. I have a feeling that the 2.5 and the 3.2 both use a 68mmTB. On my 3.2, I had to use a 996 intake "T" in order to use the bigger 74mm TB. The 996 parts also place the TB in a different location than the 986 parts, so I had to fab a tube from the airfilter to the TB. That's where I used those AirRaid parts.

[Quadcammer]

Originally Posted by j.fro

When you say the 74mm won't fit the stock intake, do you mean the curved intake tube, or the intake crossover. In looking at PET, it appears that both the 3.4 996 (cable) and the 986 2.5 use the 996 110 215 53 "intermediate piece".

I mean the tube that the TB bolts onto. I have a feeling that the 2.5 and the 3.2 both use a 68mmTB. On my 3.2, I had to use a 996 intake "T" in order to use the bigger 74mm TB. The 996 parts also place the TB in a different location than the 986 parts, so I had to fab a tube from the airfilter to the TB. That's where I used those AirRaid parts.

The 2.5L motor only uses a single crossover tube, so I believe its bigger than the one on the 3.2L. I also believe that its the same one used on the Non E-Gas 3.4 motor.

As for pre-TB, I agree, the 987 airbox is the way to go. I found one with the MAF housing as well so its just a matter of getting tubing from there to the TB.

should be fairly straightforward.

[Quadcammer]

Ok, secured an engine and 987 airbox. Also have my immobilizer codes.

Waiting on a throttle body and a solenoid wiring connector and we should be pretty good to go.

[Quadcammer]

Motor is in and running. Has some idle issues though cause it likes to rev to 3k idle with the icv plugged in. Without it the idle is around 1300. We checked for vac leaks and there arent any.

The stock throttle cable is very tight, so it may be hanging the throttle blade open slightly. Swapped icvs, no change...i left the car at my buddies house so i cant check now, just looking for a list of possibilities.

Thanks

[Quadcammer]

for anyone who cares:

1. The throttle body crossover tube from a 2.5 will work with the 3.2 intake and 3.4 throttle body.

2. fabspeed headers fit fine.

3. stock maf seems to be operating fine.

4. I used a 3.5" hump hose, stretch of 3.5" aluminum pipe, and the stock 987 cayman elbow. Not perfect, actually a bit pinched making the turn to the throttle body, but not bad.

High idle was a throttle blade that was slightly open. Re-routed throttle cable and now its fine.

Drove it a bit and it ran fine, but will get a dyno tune anyway.

[MaxD]

Excellent, I always like hearing success stories with engine swaps.

Thanks for the update.

[dghii]

Glad it's worked out well for you.

Any idea what the effect of having the 2.5L crossover tubes has on the motor vs. the stock tubes for the 3.2?

[Quadcammer]

well, the 2.5 tube is bigger, so one might think you'd get slightly better airflow, especially when combined with the 74mm throttle body. I don't think it will have a measurable impact on power one way or another.

[Quadcammer]

just to finish this up, after a somewhat trying tuning process for several operational reasons (nothing to do with the car), its back and running nicely.

At a very rich 11.8 at WOT (we tried to be conservative given that its used for track days), the car put down approximately 253rwhp on a dynapack (so take that for what its worth).

While nowhere near blindingly fast, it certain feels better than the sick 2.5

[Porsche9]

253rwhp is impressive consider stock the 3.2s are good for 250 hp at the flywheel.