since my 88 n/a failed emissions I am in the midst of changing the cat etc..upon my examination of the exhaust I removed the second pre-cat..there is nothing in it ..what I would like to know is ..are the pre-cats like a regular cat?..are they constructed the same (basically)? ..any one tested with a header and downpipe then hooked to cat and y-pipe system and passed the Ontario Canada emissions?I'm doin the air pump thing and cat (TURBOCAT) is install as of now.thanks guys..misterstyx69

 

Pre-cats are for 'startup' emmissions IIRC. They really don't do much after the car is warm. I'd pick up a Bonez Cat and install that in there. I've never heard of Turbocat so i can't speak ill or good of them but i trust bonez.

Pre-cats are constructed basically the same as the stock main cat. There is a honey comb ceramic? brick in there that does the work. If your pre-cat(s) are hollow then someone gutted them out.

 

i put on the cat from a TII..probably the same ..never looked it up ..and that's what i need ed to know ..that was QUICK..I THANK YOU..1987RX7guy!..now to get pre-cats..or go ahead without..anyone run hollowed precats and stock cat and pass emissions in ONT,Canada?

 

Your welcome. While I don't have to pass emmissions at all here in south tx i know that many people run a small amount of alcohol in their fuel tank with about 2-4 gallons of fuel in it. Make sure your car is fully warmed up. Try driving it really hard right before you put the alcohol in(right before you go test it) Don't drive it hard with the alchy in it though. Drive it nicely afterwards to the nearest gas station and then fill it up to dillute the alchy.

 

Yeah I pretty much only run 1 cat on my cars. The Bonez system is good and will last a long time. I use Magnaflow which is cheap, has good flow, but only lasts 20-30K miles if you continuously use it (hint hint).

Writeup here:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/pics-hp-gained-magnaflow-vs-bonex-cats-321221/

Pictures:

 

shiny..give it up!