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Turbo downstream from catalytic converter

Posted: 2021 Aug 25, 18:41
by efloth
Seem like a bad idea? Not trying to build a drag car just looking to add some HP for towing on my 300 Inline 6 1-4k rpm. Pulled some inspiration from here: https://www.youtube.com/watch?v=SZoV6E5DDXI

Living in California wanting to install a turbo that could be easily removed for bi-annual inspection.

Any thoughts?

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 25, 19:00
by decipha
cats wont last long and youll have bad turbo lag and youd have no afr feedback as o2s cant work

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 25, 19:40
by efloth
Ahh O2s have to be downstream from the turbo. That makes sense thanks. So I'll basically build a complete straight pipe turbo system and tear it all off every two years.

On the tuning side of things, is it as simple as scaling spark and VE table to load beyond 1?

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 25, 20:56
by decipha
not on the old speed density stuff. Under boost those old map sensors go from reporting 0 vac to full vac so youd have to create a new alpha-N ve table to use in boost. Not ideal with a turbo since the relations between throttle and load are not linear with turbos but it would be the easiest method.

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 25, 21:10
by efloth
That's too bad. Is a aftermarket map sensor out of the question? Better to just do a MAF conversion?

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 25, 22:21
by decipha
u can make anything work

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 26, 15:55
by efloth
I found this old post. Did you ever find a 2 or 3 bar MAP with frequency output?

https://eectuning.org/forums/viewtopic. ... sor#p82099

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 27, 01:48
by jsa
Escort Cosworth MAP is 2.5bar.

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 27, 06:51
by red5.0fogger
You could install a test pipe in place of the cat when using the turbo. Keep it free of any exhaust leaks and possibly use header wrap to hold in some of the heat. Use a small turbo and it might be worth it.

Re: Turbo downstream from catalytic converter

Posted: 2021 Aug 27, 11:04
by efloth
Nice info thanks guys. Looks like china even makes a cosworth map sensor now:

https://rover.ebay.com/rover/0/0/0?mpre ... 1133741848


Would this work? Simple as adjusting FN324?