2.7 swap

[truegearhead]

Thanks for reaching out over IM. As you know I put a 2.7l in my 2.5l car. You need to use the 2.7 intake manifold, and the 2.5l crossover and throttle body and the 2.5l wiring harness. The vacuum port for the second cross over can just be blocked. I used the factory 2.5l ecu. It dyno’ed at more power to the wheels then a 2.7 is supposed to make at the crank and ran great. If you need anymore help let me know, happy to help

Edit: I also used fuel rail and return system from the 2.5

[truegearhead]

This is what the hybrid manifold setup looks like all said and done. 2.7L runners, 2.5L throttle body cross over and 2.5L mechanical cable throttle body. Oddly the 2.5L throttle body and cross over is much larger than the 2.7L one which may be why this setup made so much more power than a standard 2.7

[Dllrd23]

Originally Posted by truegearhead

This is what the hybrid manifold setup looks like all said and done. 2.7L runners, 2.5L throttle body cross over and 2.5L mechanical cable throttle body. Oddly the 2.5L throttle body and cross over is much larger than the 2.7L one which may be why this setup made so much more power than a standard 2.7

Still plodding along with this project. Had a few people ask if the throttle cable will still reach even though the throttle body has been essentially “moved back” from its original location in the 2.5. What was your experience?

[Dllrd23]

Originally Posted by truegearhead

Thanks for reaching out over IM. As you know I put a 2.7l in my 2.5l car. You need to use the 2.7 intake manifold, and the 2.5l crossover and throttle body and the 2.5l wiring harness. The vacuum port for the second cross over can just be blocked. I used the factory 2.5l ecu. It dyno’ed at more power to the wheels then a 2.7 is supposed to make at the crank and ran great. If you need anymore help let me know, happy to help

Edit: I also used fuel rail and return system from the 2.5

Injectors from the 2.5 or 2.7 or are they the same?

[truegearhead]

Originally Posted by Dllrd23

Injectors from the 2.5 or 2.7 or are they the same?

I don’t know, I used the 2.5 injectors. With such a small displacement increase the computer will just adjust the injector duty cycle to make it work.

[flmont]

Do you remember how much larger the intake cross over tubes are ?? Thanks Frank

[truegearhead]

Originally Posted by flmont

Do you remember how much larger the intake cross over tubes are ?? Thanks Frank

Take a look at the photo below, you can see the rubber hose it’s stretched from the smaller diameter 2.7 to the larger 2.5 cross over. The ID of the 2.5 is the same size as the 2.7 OD

[Dllrd23]

Originally Posted by flmont

Do you remember how much larger the intake cross over tubes are ?? Thanks Frank

I’ll measure mine when I assemble them.

[Dllrd23]

I was able to put in a few hours this weekend. Removed intake and fuel injectors. In the process of cleaning up the 2.5L harness. Removed exhaust had to drill out 5 of 6 bolts. Quite a PITA. Removed Auto trans (tip). Took 3 hours as nose of converter was stuck and I didn’t want to pry too hard and break anything. Now I am having trouble with the flex plate. Rusted on. As the name implies it wants to flex too much when trying to pop it off. Any tips or tricks to this?

[Dllrd23]

Originally Posted by Dllrd23

I’ll measure mine when I assemble them.

The ‘02 was 87mm
The ‘99 was 97mm

[Dllrd23]

Originally Posted by flmont

Do you remember how much larger the intake cross over tubes are ?? Thanks Frank

‘99 is 97mm
‘02 is 87mm

Rookie mistake. I replied to myself. I’m going to buy some silicone reducers 3.75 to 3.5 and try them.

[Dllrd23]

Originally Posted by flmont

Do you remember how much larger the intake cross over tubes are ?? Thanks Frank

I mocked up the intake and the silicone boots fit perfectly. They were 3.75 to 3.5 reducers. They were 3” long so I had to trim 3/4” from each side to make them close to the original boot size. I’ll try to get pics up later.

[Dllrd23]

Originally Posted by truegearhead

Thanks for reaching out over IM. As you know I put a 2.7l in my 2.5l car. You need to use the 2.7 intake manifold, and the 2.5l crossover and throttle body and the 2.5l wiring harness. The vacuum port for the second cross over can just be blocked. I used the factory 2.5l ecu. It dyno’ed at more power to the wheels then a 2.7 is supposed to make at the crank and ran great. If you need anymore help let me know, happy to help

Edit: I also used fuel rail and return system from the 2.5

Did you only use the crossover with the throttle body or both crossovers?

[truegearhead]

Originally Posted by Dllrd23

Did you only use the crossover with the throttle body or both crossovers?

I used both, the non-throttle body cross over has a flapper in it that the 2.5l ecu can’t handle so I just blocked the vacuum line that controls it.

[Dllrd23]

Originally Posted by truegearhead

I used both, the non-throttle body cross over has a flapper in it that the 2.5l ecu can’t handle so I just blocked the vacuum line that controls it.

I apologize for what I now see was a not so smart question. I did not realize the ‘99 only has the one crossover.

[ike84]

Originally Posted by truegearhead

Thanks for reaching out over IM. As you know I put a 2.7l in my 2.5l car. You need to use the 2.7 intake manifold, and the 2.5l crossover and throttle body and the 2.5l wiring harness. The vacuum port for the second cross over can just be blocked. I used the factory 2.5l ecu. It dyno’ed at more power to the wheels then a 2.7 is supposed to make at the crank and ran great. If you need anymore help let me know, happy to help

Edit: I also used fuel rail and return system from the 2.5

I find this fascinating - any idea where the power came from? Did you get any afr readings? Maybe it was running lean and that's where the power came from? Maybe the resonance flapper is actually a handicap (the idea, while I understand the intended purpose, just seems absolutely ridiculous) and deleting it provided a smoother intake flow?

Sent from my POCOPHONE F1 using Tapatalk

[JFP in PA]

Originally Posted by ike84

I find this fascinating - any idea where the power came from? Did you get any afr readings? Maybe it was running lean and that's where the power came from? Maybe the resonance flapper is actually a handicap (the idea, while I understand the intended purpose, just seems absolutely ridiculous) and deleting it provided a smoother intake flow?

Sent from my POCOPHONE F1 using Tapatalk

You need to read up on Helmholtz resonance technology before call that device a handicap.....................

[ike84]

Originally Posted by JFP in PA

You need to read up on Helmholtz resonance technology before call that device a handicap.....................

I'm not sure I understand what you mean - Helmholtz resonance refers to dynamic resonance inside of a closed container with a single point of entry.

I understand the purpose of the valve - it is porsche's version of a variable length intake that utilizes in the concept of longer length results in smoother flow which increases velocity into the valves for enhancement of midrange torque, and but utilizing shorter intakes at low rpms and high rpm in order to decrease overall resistance of the system.

My use of the term handicap simply is a reflection of my doubt about the system's ability to accomplish this task. There would need to be a standing wave whose frequency rises in correspondence with the motor rpm or else the system could actually work in reverse and be pushing air away from the open valves. This would be exceptionally difficult to accomplish since we're talking frequency in the 100hz range. Anything other than perfect synchrony would hurt performance. Hence...handicap.

You seem to be one of the most experienced people in the forum in regards to the form and function of these machines. What do you think about the increased torque output of running a 2.7l on a 2.5l tune without a resonance flapper?



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[truegearhead]

Originally Posted by ike84

I find this fascinating - any idea where the power came from? Did you get any afr readings? Maybe it was running lean and that's where the power came from? Maybe the resonance flapper is actually a handicap (the idea, while I understand the intended purpose, just seems absolutely ridiculous) and deleting it provided a smoother intake flow?

Sent from my POCOPHONE F1 using Tapatalk

We did check AFR during the dyno run, if I could find the damn graph the AFR readings are plotted on the same graph as the power curve. I was completely surprised by the addition HP, I was only swapping the 2.7 in because my 2.5 blew up (failed accusump) and I had a cheap line on a 2.7.

[Dllrd23]

Progress today: Had high hopes of getting a lot done on the 2.7 as my first Pelican shipment has arrived. Water Pump, T-stat, 4 camshaft seals, Pelican "good-as-new" IMS bearing, tensioner o-rings and seals, and new AOS. I fabricated some camshaft holders out of a piece of stock and they worked better than expected. Pulled the tensioners and nothing moved. Went to use my homemade IMS bearing puller and discovered that the threaded shaft on the center blank was smaller that that on the 1999 2.5l boxster that I made the tool for. you can see video of the tool and the results from the 2.5 here: https://youtu.be/3WvianmKEAg Anyway, I'm going to have to make some corrections to the tool tomorrow at work and then hopefully pull and install the bearing tomorrow. I videoed the whole thing and will be posting to You Tube as well as pics/Narrative here. If you want to follow progress, please subscribe to the channel associated to the link above or check back here for updates. I'm really enjoying this project and excited to share with anyone interested. Again, thanks for following and I hope to have some pics up this week.