Simple boost question experts chime in

[rocksmith]

so I have a 1987 mostly stock Gn
It has 42 lbs in fpr and a air filter
Car runs great
I'm considering removing the cat and upgrading the chip.
It's a old reds chip
Car runs great no detonation prob because the combo is so mild

Question if I remove the cat what do I have to due as a rule of thumb
I'm assuming add more fuel ?
The car runs a max of 12lbs
Now, but normally 10 lbs
I know replacing the chip ..... You guys are going to say
But what's a good reliable combu using a stock turbo ?

 

[John Larkin]

If your only goal is to remove the cat for a little more power, then a little more fuel is likely going to be needed. Buy yourself a Scanmaster and a Caspers Audible Knock Sensor so you can see what the O2 (oxygen sensor) is saying at wide open throttle and hear if you get knock (it's loud). These will let you tune the car better also - they are not a waste of money. A Turbotweak chip should be on your shopping list too. I would think you could up the boost to 15-16 on 93 octane and not get any knock. Hopefully with those injectors a good fuel pump was installed at the same time.

 

[kels87gn]

I hate to jump in but are you saying a little fuel is needed to be added once the cat is deleted. I deleted the cat and do notice a couple degrees of knock at wot that wasn't there before the removal.

 

[That GN Guy]

Call me crazy, but logically I would think if you cut the whole exhaust off just before the cat you wouldn't need any modification to the programming. Removing the cat and inserting a straight pipe wouldn't drop back pressure enough to cause a lean condition, the turbo would however spool up faster, but boost pressure would remain the same.

If there was a difference I would think it would be negligible.

I would also think a new Turbo Tweak chip would be an upgrade for reliability, idle quality etc.

 

[Shawn N]

You will gain a few lbs of boost by removing the cat for it is restriction in the exhaust system. Same thing will happen although slightly less when going to a larger intercooler. I highly recommend visiting or calling Eric at Turbo Tweak for a more modern chip. Red's chips were pig rich back in the day. If your not racing and just street driving the stock turbo is ideal or you can get another 25 horses with a TA-49 and not have to change anything out (air intake, injectors, intercooler, actuator, torque conv, etc). It would be wise to buy afr gauge or scanmaster to monitor things closely. I would also get rid of the stock MAF sensor (if it's still on the car) and go to a LT-1 type sensor and translator. A RJC power plate is another good investment too.

 

[EVIL]

You will gain a few lbs of boost by removing the cat for it is restriction in the exhaust system.

That is incorrect.

The restriction is what causes the boost build up.

Removing exhaust restrict, making it more free flowing, in theory, should drop boost.

D

 

[bison]

That is incorrect.

The restriction is what causes the boost build up.

Removing exhaust restrict, making it more free flowing, in theory, should drop boost.

D

No


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[EVIL]

Do tell

D

 

[1952ray]

Do tell

D

What can you do,when Brian says NO, it's NO.
Ray

 

[EVIL]

Soooooo a freerer flowing exhaust makes your boost go up?

D

 

[No disintegrations]

If you let more exhaust out of the cylinders you get a better fill on the next cycle. Then you get more drive pressure for the next cycle. The drive pressure goes up, boost goes up.

If you weld the exhaust shut,. It won't run for long will it? Or make it exhaust through a 1/4 inch washer. Another way to look at it.

 

[bison]

L


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[hensleyt]

Why is your boost so low 10#-12#?

 

[EVIL]

What can you do,when Brian says NO, it's NO.
Ray

Gee, I don't know, is expecting an explanation too much to ask for?

I clearly remember a long thread a while back explaining it the way I sated.

So much for reading up on here.

D

 

[1952ray]

Man

Gee, I don't know, is expecting an explanation too much to ask for?

I clearly remember a long thread a while back explaining it the way I sated.

So much for reading up on here.

D

Man I'm sorry, didn't mean anything, it's just that Brian is rarely wrong if ever. So no means it was the opposite of what you posted. Wasn't trying to piss you off

 

[bison]

Man


Man I'm sorry, didn't mean anything, it's just that Brian is rarely wrong if ever. So no means it was the opposite of what you posted. Wasn't trying to piss you off

Basic physics. To have gas flow you are going from high pressure to low pressure. The more the differential the more flow.


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[EVIL]

Man


Man I'm sorry, didn't mean anything, it's just that Brian is rarely wrong if ever. So no means it was the opposite of what you posted. Wasn't trying to piss you off

I'm not pissed man.

No woories.

Basic physics. To have gas flow you are going from high pressure to low pressure. The more the differential the more flow.


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Thank you.

When I typed that, I read it few few times before posting it because something seemed off.

Then I was pretty confident in what I had read and here we are.

I've tried searching for said thread but haven't found it yet.

It is here somewhere.

You learn something new every day and as the days go on you learn that what you learned wasn't accurate.

What to do!

Thanks
D

 

[turbo89]

Call me crazy, but logically I would think if you cut the whole exhaust off just before the cat you wouldn't need any modification to the programming. Removing the cat and inserting a straight pipe wouldn't drop back pressure enough to cause a lean condition, the turbo would however spool up faster, but boost pressure would remain the same.

If there was a difference I would think it would be negligible.

I would also think a new Turbo Tweak chip would be an upgrade for reliability, idle quality etc.

Not true.. boost will go up . .I bet atleast 2 psi .. it could go up more depending on the cat.. and he may need to add more fuel to compensate

best to check with scan tool when he does remove the cat

 

[turbo89]

That is incorrect.

The restriction is what causes the boost build up.

Removing exhaust restrict, making it more free flowing, in theory, should drop boost.

D

Uhh .. NO .. this is ASS BACKWARDS ...

Boost will go up with the CAT off

 

[Gene Van Horn]

Just take it off, on your car it should not change a thing. Your talking plus or minus's here so close they dont meen crap. Hell most of our cats were gutted lomg ago to begin with. I eliminated mine long ago,but my brother in law owns an inspection station.