Currently have an 85 with an 89 TPI motor no longer need to pass emmission what could I eliminate to increase HP how much involved. Thanks

 

There is very little to be gained. If the cat isn't clogged there are a few pony's available there. More, if it's clogged. The AIR pump takes very little power to turn, but removing the entire AIR system cleans up the engine bay. That's about it, for power.

RACE ON!!!

 

ugh. the old "I have emissions and they kill performance".

Well, with the L98, that's half right...

Here is what I would do:

1) air pump eliminator
2) Long tube headers
3) 2 bullet cats
4) Borla NASCAR style X-pipe
5) straight pipes to mufflers
6) Good mufflers - magnaflow, etc.

This setup would give you 50~60HP. It will be louder, but it will be cool.

The real issue, emissions are now a fully integrated part of the car. EGR does more then reduce NOX, it also helps reduce detonation. Electronic controls keep the mixture perfect, which helps performance and emissions. They are so intertwined.

I recommend keeping cats for 3 reasons:

1) Air quality. They do their job.
2) back pressure. Modern engines are expecting some level of backpressure. Without it, the exhaust does not scavange correctly.
3) noise. They do a nice job of containing noise.

The other half of that equation - modern cats are much less restrictive then the original cats of the 70s. Those things were pigs. The problem with the L98 is that the exhaust meets at the middle with that hokey center cat. It's a restriction. A huge restriction. I hate it. And the precats? They help only at startup. After the first mile or so, they are pretty much on vacation. The thing is, if you install good bullet cats on the headers, you will have the same net effect. If anything the exhaust I suggest emulates the LT1 setup. And that is a very low restriction exhaust.

Oh, I assume you have a waiver cause your car is either an antique or just too old for PA to care?

 

Emissions wise, I see you only address the same two I did. His '85 has no pre-cats. Just the large, oval inlet, center cat. I agree on the EGR, and of course the PCV isn't up for discussion.

RACE ON!!!

 

[QUOTE=bogus], if you install good bullet cats on the headers, you will have the same net effect. QUOTE]


While I am not in the same place as the orignal poster I am getting ready to put the headers (Headman) on my 89 Vette. I want to replace the huge honking cat with two high flow cats. Can you suggest a pair that will work well.

Also, do they get mounted right at the headers or more towards the middle like the stock one? I was also thinking about adding a pair of dumps that have a butterfly on them (So I can not open it all the way for the backpressure). If I put the cats right at the headers this is going to make it real hard to do.

Tim

 

Ok, point #1, you need some backpressure. Didn't you read my post from earlier?

Check with carsound (a part of Magnaflow) or Random tech.

I would put the cats right off the headers, or, run a bent pipe back and put them side by side near where the main cat sits.

 

Yes, I know that motors need backpressure.. That is why I said I was going to have a butterfly on it so I can control how much it's open or closed. If I don't open them all the way I can create a backpressure. I will just have to find that sweet spot for the pressure and the sound.

Thanks for the tip on who to see about the cats.

 

i live in york about 1 1/2 hours from you i removed all my emissions (i also have a 85) took my factory manifolds off and welded the air pipe's cloed removed egr,charcole canister,all the lines ,egr sensor i have had no problems as of yet good luck

 

I doubt you will ever feel the difference after removing all that stuff. The engine was designed to run with it and I doubt it will run as well with it removed. I remember that when the cars were first coming out with the smog equipment every shade tree mechanic was removing it from their cars. Well it wasn't long til they had to have them inspected and they had to put it all back on. Most had to go out and buy the stuff as they had thrown theirs away. The junk yards made a fortune off them, charging almost as much as new parts. Where you live may not require inspection now but the feds force it upon you sooner or later. My advice would be to leave it all on and build your motor the right way. My 85 runs mid 12's through stock mufflers and passes California smog tests. Yeh, I know, I,m too old.

 

I have everything in place on both my vetts.
Both run in the 11's
No headers on eather and all stock.
My new motor for the 86 will run 10's and it will still be stock.
Change the TQ converter trans go kit, install a set of rear gears.
That will make it go fast.

 

take it all out cleans up the engine bay very nicely;