2 Port Or Not 2 Port? That Is The Question!
09-09-2003, 04:00 AM
#1
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Join Date: Sep 2003
Location: Los Angeles, California
Posts: 3
I just bought a 94 Rx7. I am going to build it up right from the beginning.With the stock twin turbo setup. I have my game plan very much set but I need one peice of info to complete it.
I know alot of you guys are just gonna tell me to "port it", but I cant trust the power hungry right off the bat. I want the added horsies too yah know, but I dont want to sarcifice reliability and funtionality.
Here we go then.. I have already know enough to decide I will not Stage 2 street Port and I will not Bridge port... Too many downsides like bad idleing and low end power loss. Plus I only want about 320 RWHP max, not 500 im not building a track car.
So if I do decide to port it will be a mild street port. Even though a mild street port seems reasonable I have read bad stories about people who did everything right and still ended up with bad results possibly caused by the street port. heres an example http://www.scuderiaciriani.com/rx7/porting.html
He seemingly did everthing right and he has a power fc to accomodate any added Gas or Air flow needed by the porting process, still, its possible that he didnt tune his PowerFc correctly to adjust to the port...... and his low vacuum pressure could be from not replacing cracked vacuum lines in the system. Sure it possible his Idle speed just needs to be increased or his ignition system is not up to par, but someone who has done all that to his car would see that one no problem, ! He did almost everthing I am going to do and ended up with a poorly idleing ride with bliping and popping. I dont want that now do I? I want mine to purr like a lion! I have read many articles on finely tuned Rx7's by respectable places like M2 and they didn't go for the street port , and why not is my question, are they seeing something I am not. Someone who knows whats up Fill me in. THX - Mndfck2000
I know alot of you guys are just gonna tell me to "port it", but I cant trust the power hungry right off the bat. I want the added horsies too yah know, but I dont want to sarcifice reliability and funtionality.
Here we go then.. I have already know enough to decide I will not Stage 2 street Port and I will not Bridge port... Too many downsides like bad idleing and low end power loss. Plus I only want about 320 RWHP max, not 500 im not building a track car.
So if I do decide to port it will be a mild street port. Even though a mild street port seems reasonable I have read bad stories about people who did everything right and still ended up with bad results possibly caused by the street port. heres an example http://www.scuderiaciriani.com/rx7/porting.html
He seemingly did everthing right and he has a power fc to accomodate any added Gas or Air flow needed by the porting process, still, its possible that he didnt tune his PowerFc correctly to adjust to the port...... and his low vacuum pressure could be from not replacing cracked vacuum lines in the system. Sure it possible his Idle speed just needs to be increased or his ignition system is not up to par, but someone who has done all that to his car would see that one no problem, ! He did almost everthing I am going to do and ended up with a poorly idleing ride with bliping and popping. I dont want that now do I? I want mine to purr like a lion! I have read many articles on finely tuned Rx7's by respectable places like M2 and they didn't go for the street port , and why not is my question, are they seeing something I am not. Someone who knows whats up Fill me in. THX - Mndfck2000
09-09-2003, 04:11 AM
#2
Senior Member
Join Date: Jan 2003
Location: Perth, Western Australia
Posts: 267
While the motor is apart, why not port it a little bit 
Seriously, give the intake ports a few extra mm's on top by blending to reduce the sharp angle of the stock ports.
Clean up the exhaust ports by removing a little bit on the bottom of the port and make sure it's a clean transition to the sleeve.
This won't muck up your idle and it won't give you stratospheric power but will give you a slightly more efficient engine.
I've done light ports like this in the past, without going to the extent of polishing and port matching the runners, and it only takes half an hour but the motor feels crisper.
Oh, and yeah, most people will say "PORT IT!"
Seriously, give the intake ports a few extra mm's on top by blending to reduce the sharp angle of the stock ports.
Clean up the exhaust ports by removing a little bit on the bottom of the port and make sure it's a clean transition to the sleeve.
This won't muck up your idle and it won't give you stratospheric power but will give you a slightly more efficient engine.
I've done light ports like this in the past, without going to the extent of polishing and port matching the runners, and it only takes half an hour but the motor feels crisper.
Oh, and yeah, most people will say "PORT IT!"
09-09-2003, 04:30 AM
#3
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Join Date: Sep 2003
Location: Los Angeles, California
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So what do you think is causing this guys idle problem? I would hate to have the same thing happen to me. Do you think this is just an anomoly and whoever did his rebuild ported too much or rebuilt it wrong? I wanted to do the port but im affraid that I will run into the same problem and wont know what to do. I wont be doing the port myself so I cant watch over it.....So you have mildly ported a few engines and none of them had this problem? If you ever encountered something of this nature? Let me know all you can. Thx for the speedy response.
09-09-2003, 08:14 AM
#4
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Join Date: Jan 2003
Location: Perth, Western Australia
Posts: 267
I've just looked at that page about the idle problems. He probably has too much overlap or poor seal matching giving the low compression. I'm leaning towards possible side seal clearancing being slightly too great as the problem clears up or gets better when warm.
Of course it could also be running way too rich when cold, which will do that too.
If the intake ports on the S6 are taken down and the exhaust ports up, you will get quite severe overlap and poor idle quality, the same as a bridgeport- brap, brap, brap!
I've done quite a few ported motors now and never had a problem with idle (unless they wanted the bridge or very large extend and then they got what they wanted!) I remember one guy wanted the brap but not a full bridge so I did a half bridgeport and that thing shook at idle, rocking the car a bit with every brap! He was quite happy...
The S6 port is huge in stock form. I wouldn't recommend large porting of it for the street, or even light racing needs- you can get 500 hp out of those motors on stock porting. I would just give it a clean up like I did- below is the stock port:
Of course it could also be running way too rich when cold, which will do that too.
If the intake ports on the S6 are taken down and the exhaust ports up, you will get quite severe overlap and poor idle quality, the same as a bridgeport- brap, brap, brap!
I've done quite a few ported motors now and never had a problem with idle (unless they wanted the bridge or very large extend and then they got what they wanted!) I remember one guy wanted the brap but not a full bridge so I did a half bridgeport and that thing shook at idle, rocking the car a bit with every brap! He was quite happy...
The S6 port is huge in stock form. I wouldn't recommend large porting of it for the street, or even light racing needs- you can get 500 hp out of those motors on stock porting. I would just give it a clean up like I did- below is the stock port:
09-09-2003, 08:17 AM
#5
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Join Date: Jan 2003
Location: Perth, Western Australia
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And this is an example of a cleaned up port- no blending of the runner- just taking out the port orifice a bit. You can go the whole hog and some of the guys on this forum have done it very well, but you have to be real careful yuo don't break through to the coolant passages!
09-09-2003, 10:21 PM
#6
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THX... I really mean it.
So what that guy is experienceing is not normal then..... I was hopeing it was someting unusual Great to hear that!
What modifications are needed on the PowerFC to accomodate the street port. I am aware that the PowerFc has pre-programmed maps for intake/DP/exaust and other bolt-ons, but what adjustments are are needed to accomodate the street port.
I ask this because... I looked into an ECU re-program by M2 and their reprogrammed ECU's say "Not for Ported engines". and it made me think there must be a reason. Teach me Yoda....Thanks again you got the knowledge indeed! Thanks for sharing some.
So what that guy is experienceing is not normal then..... I was hopeing it was someting unusual Great to hear that!
What modifications are needed on the PowerFC to accomodate the street port. I am aware that the PowerFc has pre-programmed maps for intake/DP/exaust and other bolt-ons, but what adjustments are are needed to accomodate the street port.
I ask this because... I looked into an ECU re-program by M2 and their reprogrammed ECU's say "Not for Ported engines". and it made me think there must be a reason. Teach me Yoda....Thanks again you got the knowledge indeed! Thanks for sharing some.
09-10-2003, 04:18 AM
#7
Senior Member
Join Date: Jan 2003
Location: Perth, Western Australia
Posts: 267
I'm afraid you've reached the end of my technical knowledge in this matter!
Never played with a Power FC (but I'd like to- just gotta persuade the wife not to go on holidays... ).
There are plenty of guru's on this forum that have Power FC's, so c'mon guys, step up to the podium!
Never played with a Power FC (but I'd like to- just gotta persuade the wife not to go on holidays...
There are plenty of guru's on this forum that have Power FC's, so c'mon guys, step up to the podium!
09-10-2003, 11:56 AM
#8
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Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by mndfck2000' date='Sep 9 2003, 07:21 PM
THX... I really mean it.
So what that guy is experienceing is not normal then..... I was hopeing it was someting unusual Great to hear that!
What modifications are needed on the PowerFC to accomodate the street port. I am aware that the PowerFc has pre-programmed maps for intake/DP/exaust and other bolt-ons, but what adjustments are are needed to accomodate the street port.
I ask this because... I looked into an ECU re-program by M2 and their reprogrammed ECU's say "Not for Ported engines". and it made me think there must be a reason. Teach me Yoda....Thanks again you got the knowledge indeed! Thanks for sharing some.
So what that guy is experienceing is not normal then..... I was hopeing it was someting unusual Great to hear that!
What modifications are needed on the PowerFC to accomodate the street port. I am aware that the PowerFc has pre-programmed maps for intake/DP/exaust and other bolt-ons, but what adjustments are are needed to accomodate the street port.
I ask this because... I looked into an ECU re-program by M2 and their reprogrammed ECU's say "Not for Ported engines". and it made me think there must be a reason. Teach me Yoda....Thanks again you got the knowledge indeed! Thanks for sharing some.
if you're only looking for 320hp i would clean up the casting flash on the port and put it back together. you're looking at around 13-14psi with a full exhaust (dp,mp,cb) and hopefulley some sort of intercooler.
a friend of mine did 320rwhp with an exhaust m2 ecu and 15psi
mike
09-10-2003, 05:17 PM
#10
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Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by epion2985' date='Sep 10 2003, 11:30 AM
want to safly rev at 9k? get ceramic seals, pricy but from what I gather worth it and pays for itself 10 times and over.
mike