Gsl-Se Center Iron vs. 12a Center

BigTeddy · 11-21-2008, 03:01 PM

Quote:

Originally Posted by Jeff20B

I'd only recommend a GSL-SE plate if you were EFI so the primary injectors have enough velocity to work heap big. Otherwise with a carb, use a Y plate. What you lack in low RPM veloctiy, you make up for with midrange power. Add porting and power goes up. You can't really port the SE plates much.

Jeff is right...the only advantage of using the gsl-se plate is for the use of fuel injectors...

Not much porting can be done to the gsl-se irons...

Rogue_Wulff · 11-21-2008, 03:34 PM

Yeah, I am aware that the stock 12A primary ports are larger than what can be achieved on a 6 port center iron. Simply swapping the center iron for a 4 port, on an otherwise stock 6 port, gives the same benefits as porting, but even more than what can be got from porting the 6 port center.
With a moderate to large SP on the 4 port center, and the limited porting available on the 6 port end irons, combined with exhaust porting, one *should* be able to make even more power than a "Monster SP" on a 4 port, since the secondary ports of a 4 port cannot achieve the size of the 6 port.
This is my plan, should I ever open up my SE 6 port. I already have a RB holley style intake for the 6 port, so I will use it on the "Hybrid" 6 port. To convert to a 4 port 13B would require the purchase of a different intake, and I'd rather not have to do that. The 4 bbl carb also helps the idle quality on a 6 port, since the aux ports have the sleeves removed to use this style intake. With a big 2 bbl, it is idling off both the primary and secondary ports, but with the 4 bbl, only the primary ports are utilized at idle, unless the intake has been modified or an open spacer is used.

I'm just curious as to what kind of power is realisticly achievable thru the "Hybrid" 6 port, using a 4 port center iron, along with moderate porting. By moderate, I mean something still street freindly, that really comes alive when the loud pedal is depressed....
Of course, the stock 6 port with the RB intake and 600 edelbrock is already a HUGE improvement over my SP (mild) 12A with stock intake/carb.
BTW, I also have a 650 Holley DP for the 13B, but haven't tried it yet. I might even go blow-thru, once I have the "Hybrid" 6 port built and broken in.

Jeff20B · 11-21-2008, 03:51 PM

Wulff, you may be in danger of having too much port area if you streetport the Y intermediate. Heck you may have too much just with a stock ported Y.

I basically suck at math but I know rotarygod ran the numbers for 6 port intakes and discovered that there is a happy ratio between total port area and total flow capability of the stock intake manifolds, resulting in a little bit of natural supercharging. The RX-8 is basically perfect in port area and total manifold CFM, and that's why it has so much all around good drivability.

If you're up for a little experimenting, I'd like to recommend a course of action for you. If your current setup is pretty well dialed in and you know its quirks etc, it would be very educational to swap in a non ported Y plate and see how it changes things. Then at some later point you could do a port job on the Y and see whether it increases power or decreases. Be sure to get dyno runs as well as daily driving in on it. Then we'd have a body of information to show others contemplating bigger ports on a 6 port, and whether to recommend against it.

Rogue_Wulff · 11-21-2008, 04:24 PM

Jeff, You bring up some valid points.
My actual plan, is to swap the 13B in place of the 12A, since the 12A has oil control ring issues. This 12A would then be set aside, as a "backup" engine, in case the 13B gives up on me.
As i have time, and funds, I had planned to freshen up the 12A, then reinstall it, and freshen up the 13B. During the 13B rebuild, swapping the center iron, and mild porting is planned. I doubt I would go very radical on the porting, unless the 12A really worked well for the daily driver. Any radical ported engine would likely find a home in my SE chassis, and relegated to use as a weekend toy/track car/autox car.
The SE needs more suspension attention than I really want to do, before it can see action as the primary autox car next season, and the 12A car has coilovers and other goodies, but a smoking issue.

As for doing multiple porting/builds, I'd rather avoid doing that, as my shop time is not easy to acquire. I hate not having my own shop/garage to work in.

BigTeddy · 11-21-2008, 06:17 PM

Okay hold on guys I'm a little lost in what your talking about? Are you guys talking about the divided section on the 6 ports plates on the end irons? If so, it has been done...I got a motor sitting here in my garage with the divided port taken out and ported all the way through making it one huge port...

And might i add it was a hell of difference in performance, airflow, and just over all performance of the car and motor... Lots of tunning and hours went into it running the holley 675 avenger carb, but in the end was well worth it...

Rogue_Wulff · 11-21-2008, 08:23 PM

Nope. We're talking about the center iron.

BigTeddy · 11-25-2008, 05:37 PM

lol...okay now i follow...

scarsofcarma · 02-21-2015, 05:58 PM

Cool thread! It never occured to me I could use 12A irons w/13B housings... I think I am going to try this at some point.

11-21-2008, 06:17 PM	#20
BigTeddy Rotary Fan in Training Join Date: Sep 2008 iTrader: (0) Posts: 46 Rep Power: 0	Okay hold on guys I'm a little lost in what your talking about? Are you guys talking about the divided section on the 6 ports plates on the end irons? If so, it has been done...I got a motor sitting here in my garage with the divided port taken out and ported all the way through making it one huge port... And might i add it was a hell of difference in performance, airflow, and just over all performance of the car and motor... Lots of tunning and hours went into it running the holley 675 avenger carb, but in the end was well worth it... __________________ One Turbo At A Time Last edited by BigTeddy; 11-25-2008 at 05:37 PM..

11-25-2008, 05:37 PM	#22
BigTeddy Rotary Fan in Training Join Date: Sep 2008 iTrader: (0) Posts: 46 Rep Power: 0	lol...okay now i follow... __________________ One Turbo At A Time

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11-21-2008, 03:34 PM	#17
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	Yeah, I am aware that the stock 12A primary ports are larger than what can be achieved on a 6 port center iron. Simply swapping the center iron for a 4 port, on an otherwise stock 6 port, gives the same benefits as porting, but even more than what can be got from porting the 6 port center. With a moderate to large SP on the 4 port center, and the limited porting available on the 6 port end irons, combined with exhaust porting, one should be able to make even more power than a "Monster SP" on a 4 port, since the secondary ports of a 4 port cannot achieve the size of the 6 port. This is my plan, should I ever open up my SE 6 port. I already have a RB holley style intake for the 6 port, so I will use it on the "Hybrid" 6 port. To convert to a 4 port 13B would require the purchase of a different intake, and I'd rather not have to do that. The 4 bbl carb also helps the idle quality on a 6 port, since the aux ports have the sleeves removed to use this style intake. With a big 2 bbl, it is idling off both the primary and secondary ports, but with the 4 bbl, only the primary ports are utilized at idle, unless the intake has been modified or an open spacer is used. I'm just curious as to what kind of power is realisticly achievable thru the "Hybrid" 6 port, using a 4 port center iron, along with moderate porting. By moderate, I mean something still street freindly, that really comes alive when the loud pedal is depressed.... Of course, the stock 6 port with the RB intake and 600 edelbrock is already a HUGE improvement over my SP (mild) 12A with stock intake/carb. BTW, I also have a 650 Holley DP for the 13B, but haven't tried it yet. I might even go blow-thru, once I have the "Hybrid" 6 port built and broken in.

11-21-2008, 03:51 PM	#18
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	Wulff, you may be in danger of having too much port area if you streetport the Y intermediate. Heck you may have too much just with a stock ported Y. I basically suck at math but I know rotarygod ran the numbers for 6 port intakes and discovered that there is a happy ratio between total port area and total flow capability of the stock intake manifolds, resulting in a little bit of natural supercharging. The RX-8 is basically perfect in port area and total manifold CFM, and that's why it has so much all around good drivability. If you're up for a little experimenting, I'd like to recommend a course of action for you. If your current setup is pretty well dialed in and you know its quirks etc, it would be very educational to swap in a non ported Y plate and see how it changes things. Then at some later point you could do a port job on the Y and see whether it increases power or decreases. Be sure to get dyno runs as well as daily driving in on it. Then we'd have a body of information to show others contemplating bigger ports on a 6 port, and whether to recommend against it.

11-21-2008, 04:24 PM	#19
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	Jeff, You bring up some valid points. My actual plan, is to swap the 13B in place of the 12A, since the 12A has oil control ring issues. This 12A would then be set aside, as a "backup" engine, in case the 13B gives up on me. As i have time, and funds, I had planned to freshen up the 12A, then reinstall it, and freshen up the 13B. During the 13B rebuild, swapping the center iron, and mild porting is planned. I doubt I would go very radical on the porting, unless the 12A really worked well for the daily driver. Any radical ported engine would likely find a home in my SE chassis, and relegated to use as a weekend toy/track car/autox car. The SE needs more suspension attention than I really want to do, before it can see action as the primary autox car next season, and the 12A car has coilovers and other goodies, but a smoking issue. As for doing multiple porting/builds, I'd rather avoid doing that, as my shop time is not easy to acquire. I hate not having my own shop/garage to work in.

11-21-2008, 08:23 PM	#21
Rogue_Wulff Non Member Join Date: Jun 2008 iTrader: (0) Posts: 310 Rep Power: 17	Nope. We're talking about the center iron.

02-21-2015, 05:58 PM	#23
scarsofcarma Rotary Fanatic Join Date: Aug 2013 Location: Antioch, Ca iTrader: (0) Posts: 101 Rep Power: 12	Cool thread! It never occured to me I could use 12A irons w/13B housings... I think I am going to try this at some point.