Hello,

I need some ideias on how to change the stock exhaust to make it better.

my plan is to cut this and make it same size, but donīt know if will give different
back pressure to back rotor, since this pipe output is facing to front like in picture.





Also i plan to remove this pipe (this was suppose to be a cat, but is other thing.)






If later i can get some RB/other headers, how to block that 2 extra exhaust outputs that are next to the lower bolts?[/B]




This stuff is very heavy





By the way.

What is the best to put inside engine at the moment to clean the carbon since i have the intake and exhaust removed?

Remember that Seafoam i canīt find it here in Europe




At least the apex are there

 

I don't know what you can cut out of your exhaust manifold. I'd rod out the cat. but I don't know about the other things you were asking. As far a carbon cleanup. when you get the engine back together you could steam clean it with a simple spray bottle with some water. just remove the carb hat, rev engine to 3 or 4 grand and spray. it turns the water into steam witch will clean up the carbon. If you cant get the engine running I don't know what to do. The word around the streets is atf is bad. You could use Marval Mystry Oil also.

 

are those two small exhaust holes on the motor a 12a specific thing? i just put a RB header on my gsl-se and i dont recall seeing those, and i dont have any exhaust leaks.

 

The rear rotor have that long pipe and the output is facing the front of the car, it means that all the pressure is first going front and than coming back, so the ideia is to make it both at same size.

About the carbon, i will try the water, i have the car stop because of carb problem, so i take the exhaust apart.

 

Yes, you can see that there is a small passage were the gases pass and come out in that 2 small holes, i also have see many here on the forum but didnīt see it like that.

This car was imported from Germany, so i think it have some differences, for example, the cat is just a a pipe insid the bigher pipe, and the top is closed, so this is not letting the gases come out direct, i will remove it.

About that 2 pipes that goes inside the reaction chamber, i just donīt know if it will change back pressure whatever for the rear rotor if i cut is like the front one.

 

The tubing arrangement inside the thermal reactor serves 2 purposes, main one is to retain heat to clean up emissions, secondary one is noise suppression. The 2 small holes are on the earlier 12As, which serve a similiar function as the rectangular port under the primary intake ports on the later engines. The header flange will block those ports, but there is also a plug kit needed to replace the bolts at the bottom of the housing. Drop oil pan to see.

ATF works fine, limit soak time to less than 24 hours.

 

Ok, so it means that i can cut the tubing arragement to the same size, the only thing that i will get is more noise.

About that kit, were to get it? iīm planing to order headers from USA so it will be better to come with all the parts.

ATF does it mean Automatic transmission Fluid?

How to use it, drop some inside, turn the engine by hand in order to put ATF in each face of the rotors, and than some hours later turn the engine with starter to let the most of it come out and than start the engine with plugs and all things in place?

I have this car for less than one month, but i can tell you that i still was not able to have it running at 100% most of the time was fixing things and repair, i hope that after i made this and finish repairing the carb it will run good, and i have to say tanks to the forum and members that help a lot.

 

I start to remember and did found it.

what you were talking about the bolts is this



from this thread https://www.rx7club.com/1st-generation-specific-1979-1985-18/12a-housings-all-pretty-much-same-right-828394/

So this means that i have older housings? and if i remove (i already did) the air pump it is important to block that passages or just let it go till i get the headers?

I have notice that the carb is from a 1979 version, but o donīt know much about
this car, only that the engine was rebuild in Germany before it was exported and after that it have maybe 20k KM on it.

 

Order the plug kit with the headers. ATF is auto tranny fluid. Pour a capful in each intake port, rotate main pulley 180*, repeat 5 more times. Let sit overnight then crank engine over, spark plugs removed, to blow out most of the ATF. A small turkey baster works better than trying to pour the ATF. Some parts stores carry small ones that look like overgrown eyedroppers. If you tape off the exhaust ports, you will get better coverage internally while rotating the engine. It helps to turn the engine over by hand a few times while soaking too.

As far as modding the thermal reactor, I'd skip that and wait for the headers.

 

You wrote:

What is the best to put inside engine at the moment to clean the carbon since i have the intake and exhaust removed?

Remember that Seafoam i canīt find it here in Europe

Try a boat shop. SeaFoam was developed to de-carbon 2 stroke outboard motors. A similar product is made by several motor manufacturers. Mercury, Evenrude etc. Chrysler Combustion Chamber Cleaner is similar and may be available.

 

b 15 chemtool is another

 

I have done what i say, cut the tube to match the other one, and remove the other one that was inside the "cat" also remove airpump, and extra pipes that were not need.

here is a video with original exhaust moded

http://www.youtube.com/watch?v=p1t_aOYIVyw

 

Doesn't sound bad from inside the car. Did it backfire like that before you modded the exhaust mani?

 

It was different, before i open the Nikki and remove airpump and change the exhaust the backfire were over 4k rpm and very laud and the car didnīt run good over 4500 rpm.


But i still didnīt manage it to work 100%, on idle it still drops fuel on the top of the carb, the car runs much better, i can go over 6k rpm and change gear without the bigh back fire but there is still issues, drive it is like run a 70hp car.

By the way, at 130 140kmh the exhaust noise is small compared to the video

I think that i will go EFI