Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Performance and Technical chat

Reply
 
LinkBack Thread Tools Display Modes
Old 01-30-2021, 12:27 PM   #21
Registered User
 
Join Date: Aug 2020
Location: West Virginia
Posts: 35
Quote:
Originally Posted by flmont View Post
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 is offline   Reply With Quote
Old 01-30-2021, 12:34 PM   #22
Registered User
 
Join Date: Aug 2020
Location: West Virginia
Posts: 35
Quote:
Originally Posted by truegearhead View Post
Yep that’s it!
@truegearhead. My 2.5l harness only has 2 oxygen sensor connectors. Do you know if there is a sort of “jumper harness“ that the 2.5’s used. Also the temp(?) sensor is the front oil passage is a different connector. Do you remember if you had to change yours?
Dllrd23 is offline   Reply With Quote
Old 01-31-2021, 05:35 AM   #23
Registered User
 
Join Date: Aug 2020
Location: West Virginia
Posts: 35
Progress Report: Spent a couple of hours yesterday in the garage. I was able to rehab the 2.5 harness as it was oil soaked from the previous vehicle. I wiped down all the exposed wires with brakeclean and replaces the cloth electrical tape with the same purchased on Amazon along with some mesh wire loom for about $30. All looks pretty clean now. I mocked up the upper intake using the throttle body and runner from the 2.5 and the back runner from the 2.7. For the TB runner I used some silicone adapters bought for $9 each and trimmed them down. I removed the vac valve from the rear runner and am looking for something to plug the holes with. Lastly I wired the engine with the 2.5l harness. A couple of problems I ran into were the O2 connectors are different from 99 to 02 and I have the stock 02 manifolds on still. Also there were only 2 O2 connectors on the 2.5 harness I will have to take a closer look at the 99 exhaust (it is in a separate location) this is easily fixed I just have to decide which exhaust to go with. The MAF connector is also different. Not sure if I have the MAF from the 99 or not?? I know that this thread may not be very interesting to many as I am swapping the 2nd least desirable engine for the least desirable engine but my reason for doing so is simple. I have a very clean and good running 99 that I don't want to do anything to this satisfies my itch to tinker with the Boxster plus the cost to this point is very low (probably have 1/3 of the low book invested via some good luck and a little negotiation. Thanks for following.





Last edited by Dllrd23; 01-31-2021 at 05:38 AM.
Dllrd23 is offline   Reply With Quote
Old 01-31-2021, 05:25 PM   #24
Registered User
 
truegearhead's Avatar
 
Join Date: Jul 2011
Location: Richmond, VA (The Fan)
Posts: 897
Nice work! Keep us posted, 2.5l engines are becoming rare so this is valuable info. You may want to put an S oil cooler on while you have the engine out, nice cheap upgrade
__________________
1997 Boxster 4.2L Audi V8 Bi-Turbo
2003 911 C2
NASA HPDE Instructor
truegearhead is offline   Reply With Quote
Old 02-05-2021, 04:59 PM   #25
Registered User
 
Join Date: Aug 2017
Location: Tucson,az
Posts: 464
Thanks for the info !!
flmont is offline   Reply With Quote
Old 02-08-2021, 09:45 AM   #26
Registered User
 
Join Date: Oct 2020
Location: KY
Posts: 183
Quote:
Originally Posted by truegearhead View Post
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
__________________
2000 Box Base, currently undergoing renegade modifications
When the owners manual says that the laws of physics can't be broken by this car, I took it as a challenge...
ike84 is offline   Reply With Quote
Old 02-08-2021, 10:44 AM   #27
Registered User
 
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 5,517
Quote:
Originally Posted by ike84 View Post
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.....................
__________________
Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
JFP in PA is offline   Reply With Quote
Old 02-08-2021, 01:28 PM   #28
Registered User
 
Join Date: Oct 2020
Location: KY
Posts: 183
Quote:
Originally Posted by JFP in PA View Post
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?



Sent from my POCOPHONE F1 using Tapatalk

__________________
2000 Box Base, currently undergoing renegade modifications
When the owners manual says that the laws of physics can't be broken by this car, I took it as a challenge...
ike84 is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 11:56 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page