How to remove cats and air pump without perfornmace issues....
 

Hi,

I have a 88 Rally RX7 that has a N/A engine on it.

Since the car has a cage and other safety equipment, the weight is above 2,850 lbs.... so I am trying to get more power out of the N/A engine.

After reading the FAQs on these forums, I have seen that things like removing the clutch fan and other small tricks does not really work on these cars.... so the only thing I can think of is to do a straight pipe.

This is a rally car, so I do not need cats since the car does not see the street other than transits.





Now.... the problem that I have is that when I remove the cats, the valves on the passenger side of the engine (I do not remember their name) will not open since I am missing the back pressure on the exhaust....

I have read that I can stick them open, but that I would loose power at low rpm (like I have any to begin with....) as well as screw dump more gas than necessary unless I am at full throttle.

Are these two assumptions correct? Any way around it?

I have ready of a guy that used rpm to actuate the valves, but the post did not continue with any results explained...

I am sure that I am not the first one with this issues, so, any ideas on what could I do?

Thanks!!

https://www.rx7club.com/2nd-generati...itches-907824/

The result is the ports open properly. That's it. If you want to remove the air pump too, you need to use an electric air pump. Lumbar support pumps from seats have been used.

I have read the thread a couple of times now and it is a little bit difficult for me to follow. So I will ask a friend for help to see if we can make it happen.

Does anybody knows how many hp could we get out of removing the cats? 3-5hp?

Thx.

About 10HP from removing the cats. Add a header to that mix and you're up 15 - 20HP.

If you still have smog pump and air box you can save around ten pounds by removing. You will have to convert the intake which is very simple. If you remove the smog pump you will need a knew pulley and belt. I would recommend greddy's pulley package off RX7.com

Thx for the info. I will look into it.

BTW, I am also trying to figure out why would I need an electric pump if I remove the stock one and bypass the auxiliary valves....

Don't bypass the aux. port valves. You sacrifice low-end torque (what little there is) and gain nothing. Removing the sleeves/wiring the ports open hurts low-end air speed velocity.