Turbo downstream from catalytic converter

For anything machine shop / speed shop or engine specific. More technical than the range but not quite tuning specific.
efloth
Posts: 62
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Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Turbo downstream from catalytic converter

Unread post 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?
decipha
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Re: Turbo downstream from catalytic converter

Unread post by decipha »

cats wont last long and youll have bad turbo lag and youd have no afr feedback as o2s cant work
efloth
Posts: 62
Joined: 15 Feb 2021, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: Turbo downstream from catalytic converter

Unread post 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?
decipha
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Re: Turbo downstream from catalytic converter

Unread post 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.
efloth
Posts: 62
Joined: 15 Feb 2021, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: Turbo downstream from catalytic converter

Unread post by efloth »

That's too bad. Is a aftermarket map sensor out of the question? Better to just do a MAF conversion?
decipha
Posts: 1545
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Re: Turbo downstream from catalytic converter

Unread post by decipha »

u can make anything work
efloth
Posts: 62
Joined: 15 Feb 2021, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: Turbo downstream from catalytic converter

Unread post 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
jsa
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Re: Turbo downstream from catalytic converter

Unread post by jsa »

Escort Cosworth MAP is 2.5bar.
red5.0fogger
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Re: Turbo downstream from catalytic converter

Unread post 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.
efloth
Posts: 62
Joined: 15 Feb 2021, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: Turbo downstream from catalytic converter

Unread post 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?
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