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Discussion Starter #41
UPDATE: Well guys, first problem with this install. As we were attempting to re-install the plenum and TB on Sunday, the actuator in the back of the plenum snapped off from hitting the back of the engine bay :eek: I called the nearest dealer and was able to buy it for $128 and it should be here by tomorrow, but this was a pretty sad moment. Even the second actuator became useless when we pulled off the vacuum line and tore out the piece that holds it in place🤦‍♂️ Tomorrow once we have the actual part we'll try again and hopefully be a little more careful but man was that upsetting! Especially since the car has to sit there until we can get this fixed! Well, hopefully we'll get in done this week and I can update you guys with better news. Stay tuned!
Another update here! Finally got the actuator in, installed the plenum and throttle body and got the car going! I’ll admit, at first it had a bit of a rough start while the ECU got used to the airflow but now she’s breathing great! butt dyno definitely notices a difference, hoping to get some proper numbers up soon though. Along with this though, I was wondering if anyone had upgraded the fuel injectors after doing this upgrade? It just seems like a natural follow-up after the big change in air flow
 

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2.9 987.2 Here.

The drone is because of the design of the interior. It's going to be very difficult to escape it. There is a large pocket of trunk space right above the muffler and the sloping shape of the hatch and glass is what amplifies and projects the resonance of the exhaust into the passenger area. It's unfortunately harmonically tuned that way. The only real way to "eliminate drone" would be to find a way to section off the rear trunk from the cockpit... Mufflers under the cabin always cause drone, thats why hatchbacks generally drone more than sedans. Most of the drone is around 2000-3000rpm, so I just keep it in a higher gear when climbing inclines... This is also why you see a lot of valved exhausts for this car, so you can escape the drone when you are cruising and turn the noise back on when you're having fun.

From my understanding, putting a GT3 TB on the 2.9 isn't beneficial like it is on the 3.4. It flows too much for the engine and you will lose power. Thats why IPD sells a separate plenum for the 2.9 that doesn't use a larger TB. I looked into if the "S" TB would be an upgrade to the 2.9 but they use the same TB on the 987.2. (In 987.1 form, putting an S TB on a 2.7 is an upgrade). In order to properly utilize a GT3 sized TB on a 2.9, you would likely need to improve flow through the heads and you'd be giving up low end power/toque for more top-end power.

Stock you are at about 225whp. FBO you can get that number up to closer to 260whp (290-300crank).
Thats intake, plenum, headers, exhaust, tune.
Don't bother getting a tune until you hav all your bolt ons. I suggest a proper Dyno tune over a "flash tune" for obvious optimization benefits.

Adding some input based on my mods, in case you are considering "what's next, what's worth it?"

My mods/comments:
- Soul race-catted long tube headers -> You can feel the slight bump in power even without a tune. On the 987.2 they moved the 2ndary cats from the rear mufflers into the headers, so there are 2 cats in each manifold now. Headers make the biggest power difference on the 987.2's. You don't notice a huge sound difference unless you already have a catback, then you notice how much louder race cats (or cat-less) can be.

- Borla (coming) -> As mentioned above, catbacks make less difference on a .2 vs a .1. However there are some flow benefits, so you can net yourself a little bump in power. This mod is mostly to shed weight and add fierce sound (and drone lol).

- Numeric racing shifter assembly + Cables -> My OEM (nylon) cables snapped. The stainless cables will prevent that from happening again. The tradeoff is slightly more transmission noise added to the cabin. I put dynomat on the cable ends and inside the console to mute it. The OEM assembly, and OEM SSK are all made of plastic and utilize bushings. There is a lot of flex in the OEM assembly. The Metal Numeric unit is metal and ball bearings and is substantially more solid and refined. The assembly makes a MASSIVE difference to shifter feel. Now it feels like I'm racking a rifle every time I shift; the assembly clanks into place with a metal-on-metal feel thats tight, crisp, heavy and smooth. This was probably the best mod I've done, or close to it.

- KW coilovers > Lowering on stiffer suspension makes it feel like a proper sports car. Corner balancing makes everything feel how it should.

- Gt3 Master + Stainless lines -> FIXES the brake feel. 10/10 mod that should be on everyone's list. A must-have mod.

- 3rd rad -> If you ever plan to track it or live in a hot climate this is a must have. Change your waterpump and thermostat while you're flushing out the system.

- Wider wheels (9/10 with 255/285) -> Goes without explaining, raises the limit on grip.

- Harness bar/roll hoop -> I added it the same time I added hard-back seats. Stiffens up the chassis, serves as a rear strut brace. You can feel the difference, the car feels more rigid.

- GT3 Buckets -> Personal preference. I needed something to keep me in place with all my added handling mods. Definitely makes the car less practical but it's not my daily.

When (if) my clutch ever goes and the trans comes down, I will be doing a proper mechanical LSD.
 

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Discussion Starter #43
2.9 987.2 Here.

The drone is because of the design of the interior. It's going to be very difficult to escape it. There is a large pocket of trunk space right above the muffler and the sloping shape of the hatch and glass is what amplifies and projects the resonance of the exhaust into the passenger area. It's unfortunately harmonically tuned that way. The only real way to "eliminate drone" would be to find a way to section off the rear trunk from the cockpit... Mufflers under the cabin always cause drone, thats why hatchbacks generally drone more than sedans. Most of the drone is around 2000-3000rpm, so I just keep it in a higher gear when climbing inclines... This is also why you see a lot of valved exhausts for this car, so you can escape the drone when you are cruising and turn the noise back on when you're having fun.

From my understanding, putting a GT3 TB on the 2.9 isn't beneficial like it is on the 3.4. It flows too much for the engine and you will lose power. Thats why IPD sells a separate plenum for the 2.9 that doesn't use a larger TB. I looked into if the "S" TB would be an upgrade to the 2.9 but they use the same TB on the 987.2. (In 987.1 form, putting an S TB on a 2.7 is an upgrade). In order to properly utilize a GT3 sized TB on a 2.9, you would likely need to improve flow through the heads and you'd be giving up low end power/toque for more top-end power.

Stock you are at about 225whp. FBO you can get that number up to closer to 260whp (290-300crank).
Thats intake, plenum, headers, exhaust, tune.
Don't bother getting a tune until you hav all your bolt ons. I suggest a proper Dyno tune over a "flash tune" for obvious optimization benefits.

Adding some input based on my mods, in case you are considering "what's next, what's worth it?"

My mods/comments:
- Soul race-catted long tube headers -> You can feel the slight bump in power even without a tune. On the 987.2 they moved the 2ndary cats from the rear mufflers into the headers, so there are 2 cats in each manifold now. Headers make the biggest power difference on the 987.2's. You don't notice a huge sound difference unless you already have a catback, then you notice how much louder race cats (or cat-less) can be.

- Borla (coming) -> As mentioned above, catbacks make less difference on a .2 vs a .1. However there are some flow benefits, so you can net yourself a little bump in power. This mod is mostly to shed weight and add fierce sound (and drone lol).

- Numeric racing shifter assembly + Cables -> My OEM (nylon) cables snapped. The stainless cables will prevent that from happening again. The tradeoff is slightly more transmission noise added to the cabin. I put dynomat on the cable ends and inside the console to mute it. The OEM assembly, and OEM SSK are all made of plastic and utilize bushings. There is a lot of flex in the OEM assembly. The Metal Numeric unit is metal and ball bearings and is substantially more solid and refined. The assembly makes a MASSIVE difference to shifter feel. Now it feels like I'm racking a rifle every time I shift; the assembly clanks into place with a metal-on-metal feel thats tight, crisp, heavy and smooth. This was probably the best mod I've done, or close to it.

- KW coilovers > Lowering on stiffer suspension makes it feel like a proper sports car. Corner balancing makes everything feel how it should.

- Gt3 Master + Stainless lines -> FIXES the brake feel. 10/10 mod that should be on everyone's list. A must-have mod.

- 3rd rad -> If you ever plan to track it or live in a hot climate this is a must have. Change your waterpump and thermostat while you're flushing out the system.

- Wider wheels (9/10 with 255/285) -> Goes without explaining, raises the limit on grip.

- Harness bar/roll hoop -> I added it the same time I added hard-back seats. Stiffens up the chassis, serves as a rear strut brace. You can feel the difference, the car feels more rigid.

- GT3 Buckets -> Personal preference. I needed something to keep me in place with all my added handling mods. Definitely makes the car less practical but it's not my daily.

When (if) my clutch ever goes and the trans comes down, I will be doing a proper mechanical LSD.
Thanks for the insight!

Your points about the acoustics makes sense and also echos other comments I’ve heard/read so I’ll just have to learn to deal with it to a point. I read there may be a way of lessening it by adjusting the height on the exhaust mounts so we’ll see how that goes.

As for the plenum + TB, it actually feels better. It could just be my impression because I don’t have proper numbers to back it, but it is coupled with the exhaust so it has some extra air in and out. I’ll be installing 200 cel catted headers on Sunday so maybe this balances out even further and I get some more performance from it. Also, from my conversation with IPD it looks like the competition plenum has been shown to improve performance on the 2.9 model as well.

The tune will come as soon as I get the headers installed, already have that planned out ;)

Your build sounds great! I live in south florida so I think the 3rd radiator will come in March once it starts getting warm again, apart from that the coil overs are definitely happening at some point. Hadn’t considered the GT3 master cylinder for the braking system, was that an easy swap? Definitely had already considered the steel lines but the GT3 master is an interesting idea.
 

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Discussion Starter #44
Hi everyone, back for another update! Got the headers installed yesterday, I think the ECU is having a bit of trouble adjusting for it because it feels a little “winded”. Definitely sounds a bit more aggressive which I’m not too mad about. Fortunately didn’t make the drone any worse which I was a little worried about. I’ll be doing the tune sometime this week so I’m hoping that will help with that “winded” feeling.
 
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