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Lower Intake manifold help. 1991 Rx7 Fc S5 N/A

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Old 06-04-24, 06:30 PM
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Lower Intake manifold help. 1991 Rx7 Fc S5 N/A


Lower intake with the open holes where the “plungers/rods” went, possible delete with block off plates like the center plate? Or new parts required?

Snapped rod from the “housing” Was broke while engine ran since when I pulled it apart it was just floating in the lower intake

Non broken rod on top of snapped rod, with housings/canisters?

Hello, brand new to this forum and may be asking a redundant question, I could not find the information needed online so I figured I would finally ask around here, thanks for the help in advance.

First off I do not know the name of the parts I need help with as the Hanes manual I have does not go into depth and Im curious if these are a must have part for engine functionality. I was finally getting around to doing a rebuild with the knowledge and money that I have at the moment (which is not a lot lol) and noticed that the bar with plunger looking piece that sticks in the lower intake and is connected to 2 bell shaped canister/housings and cable was snapped off and the other still fully attached, I was driving the car for a while and it continued to run while this was broken off on the inside floating around, my major concern is if it is going to cause any major issues down the line for a rebuild motor, and if so where would I find replacement for it as I have scowerd the web and found nothing, and if all else fails is it possible just to put a block off plate over both sides and call that fine?

*I made this post from my iphone, sorry if the format is weird*

Last edited by LilRonin02; 06-04-24 at 06:33 PM.
Old 06-04-24, 11:39 PM
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welcome to the board.

those rods operate your auxiliary ports (ports 5 and 6) on your engine. they are supposed to remain closed until the upper RPM range where they open. if you remove the rods, you'd be better served to also remove the sleeves. whether you keep the sleeves or not, your powerband will change. the car will not function as intended.

i don't know if those parts were ever available by themselves. i guess it's worth looking into though. you will probably need to look for another manifold or look into repairing the rod (machine shop or welder) though.
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Old 06-05-24, 04:13 PM
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Originally Posted by diabolical1
welcome to the board.

those rods operate your auxiliary ports (ports 5 and 6) on your engine. they are supposed to remain closed until the upper RPM range where they open. if you remove the rods, you'd be better served to also remove the sleeves. whether you keep the sleeves or not, your powerband will change. the car will not function as intended.

i don't know if those parts were ever available by themselves. i guess it's worth looking into though. you will probably need to look for another manifold or look into repairing the rod (machine shop or welder) though.
Thank your so much for the reply and information, I will continue to look into it more as I continue on with the other parts, currently I have had no luck with finding a S5 lower intake that comes with the parts attached, everything on ebay or various websites are lacking the components, im worried I may be screwed and have to just have a shop fabricate plates to block off the little holes so there is not a opening on each end deal with the engine not working as intended, other info I managed to find stated that I would lose power in the low end of the rpm range with the missing components, I suppose as long as it will run and drive regardless it will have to do until a full s5 intake pops up down the line. Thank you again
Old 06-07-24, 08:31 AM
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Originally Posted by LilRonin02
... other info I managed to find stated that I would lose power in the low end of the rpm range with the missing components, I suppose as long as it will run and drive regardless it will have to do until a full s5 intake pops up down the line.
in essence, that is what will happen. all 6 ports will be open all the time, so you will lose some port velocity in the lower RPM ranges. the car will definitely be drivable though, so i don't think you should lose sleep over it.

also, just as another thought ... you might be able to include the S3 and S4 lower manifolds in your search. i know there are minor difference between them all, but i'm not sure the rod, itself, is one of them. i do know the S3/S4 engines used exhaust pressure to operate them, while the S5 engine used the air pump, but again, i don't know if the rod, itself, is different. so, my guess/theory is that you could get one of those older manifolds and potentially scavenge the parts you need to repair your S5 manifold. i have S3 and S4 lowers, but i have never had an S5 lower in my hands to compare.
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