Emmissions vs Horsepower:

[Phil750]

I just wanted to throw some information your way. Several people say removing the Smog system only nets one or two HP. I live in Phoenix! As soon as I had my truck (86 Chevy C-20 4speed registered as a classic) I wanted to remove the Emissions, but first I had it Dyno with 80 Hp at the rear wheels. I removed the pumps and the tubes that fed into the exhaust manifold. No wonder these trucks were bogged down. I pulled the exhaust manifolds removed the power robbing tubes, my
friend welded bolts over the holes in the manifold. Once I got it back together I immediately noticed the increase in power. So back to the Dyno I went. This time 105 Hp at the rear wheels.
Once you have it apart and see how much power is robbed by restricting the exhaust, unbelievable!
For you Phoenix guys Charlie Echols has the Dyno.
25 Hp for just a couple days work, was well worth it.

[chevybuilder18]

Originally Posted by Phil750

I just wanted to throw some information your way. Several people say removing the Smog system only nets one or two HP. I live in Phoenix! As soon as I had my truck (86 Chevy C-20 4speed registered as a classic) I wanted to remove the Emissions, but first I had it Dyno with 80 Hp at the rear wheels. I removed the pumps and the tubes that fed into the exhaust manifold. No wonder these trucks were bogged down. I pulled the exhaust manifolds removed the power robbing tubes, my
friend welded bolts over the holes in the manifold. Once I got it back together I immediately noticed the increase in power. So back to the Dyno I went. This time 105 Hp at the rear wheels.
Once you have it apart and see how much power is robbed by restricting the exhaust, unbelievable!
For you Phoenix guys Charlie Echols has the Dyno.
25 Hp for just a couple days work, was well worth it.

Lol not only did you get more hp, you have better gas milege leave those smog pumps for supercharging your briggs and strattons!

[SSC's76]

wow that's insane just the smog pumps and tube from the manifolds? did you take the converter off to?


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[Number21]

Now you need to go find about 200 more HP.

[Keckdl]

Just out of curiosity how much did the Dyno run cost?

Thanks
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[Phil750]

Mine did not have cat converter from the factory. The Dyno was 45. for each pass. I hope this will encourage others to do the same. One other benefit I failed to mention, was the knock from unleaded fuel. After removing the smog the knock went away. Idle had to be turned down about five hundred rpm.
The most important factor is those tubes that bolt into the exhaust manifold. When you look at there position you wonder how a engine ever breathed.

[sqzbox]

Originally Posted by Phil750

Mine did not have cat converter from the factory. The Dyno was 45. for each pass. I hope this will encourage others to do the same. One other benefit I failed to mention, was the knock from unleaded fuel. After removing the smog the knock went away. Idle had to be turned down about five hundred rpm.
The most important factor is those tubes that bolt into the exhaust manifold. When you look at there position you wonder how a engine ever breathed.

put a good set of headers on there anf get another 20-25 hp.

[Firebirdjones]

Originally Posted by Phil750

Mine did not have cat converter from the factory. The Dyno was 45. for each pass. I hope this will encourage others to do the same. One other benefit I failed to mention, was the knock from unleaded fuel. After removing the smog the knock went away. Idle had to be turned down about five hundred rpm.
The most important factor is those tubes that bolt into the exhaust manifold. When you look at there position you wonder how a engine ever breathed.

If it helps you any, I use the chassis dyno in North Mesa at Loud Pedal Motorsports. It's only $50 for 2 pulls so it's quite a bit cheaper as far as the dyno goes. Good group of guys over there too.

Yep the first thing I did/do on my 79 1 ton 454 was remove the smog pump. It never had converters either (over 7,000 GVW wasn't required in the 70's) and those tubes in the manifolds stick down in the airstream as you mentioned. Probably some parasitic gains from lack of another belt and pulley too.
Nice gains for no money spent

[bk2life]

Originally Posted by Phil750

(86 Chevy C-20 4speed registered as a classic)

how did you do this?

i have a 84 id like to do whatever i can to get pass emissions, i would like to not have to swap cams/add stock exhaust manifolds every year for emissions.

or pull bbc and put in sbc for emissions every year..

if i can stay away from emissions, best option yet. yes i live in phx also.

[Firebirdjones]

All you need to do in Maricopa County is register your car/truck as a classic. I'm sure you've seen the tags before. This exempts you from any testing.

They also used to require that you keep some form of collector car insurance on it as well, but I'm not sure if that is still a requirement or not.

[nobull2]

Originally Posted by Phil750

I just wanted to throw some information your way. Several people say removing the Smog system only nets one or two HP. I live in Phoenix! As soon as I had my truck (86 Chevy C-20 4speed registered as a classic) I wanted to remove the Emissions, but first I had it Dyno with 80 Hp at the rear wheels. I removed the pumps and the tubes that fed into the exhaust manifold. No wonder these trucks were bogged down. I pulled the exhaust manifolds removed the power robbing tubes, my
friend welded bolts over the holes in the manifold. Once I got it back together I immediately noticed the increase in power. So back to the Dyno I went. This time 105 Hp at the rear wheels.
Once you have it apart and see how much power is robbed by restricting the exhaust, unbelievable!
For you Phoenix guys Charlie Echols has the Dyno.
25 Hp for just a couple days work, was well worth it.

what motor is in your truck? miles? rebuilt?

[tucsonjwt]

I don't know how you get away with it. In Tucson, all vehicles newer than 1967 are checked for factory emissions - my 83 C20 gets frequent emissions anal exam most years. I was told by DMV that historic plates don't exempt you from emissions rules. I don't know about horse power, but my 73 454 C20 got about the same mpg as my smog laden 83 454 C20 9-11 city, 13-14 hwy.

[Hevy]

I was going to go the "classic insurance" route on my '77 but they are very restrictive. You have to park inside a garage (not in the driveway), can only drive so many miles a year, send pictures in of every inch of your truck, and don't even think of hauling anything in the bed... if you get in a wreck and had something in your bed, denied!

Now I just tune and pass.

[Skunksmash]

Originally Posted by chevybuilder18

leave those smog pumps for supercharging your briggs and strattons!

Dang. Now I want to know if anybody ever really did that lol.


But I would yank all the smog stuff off my 87. Except for the fact that my computer would probably throw a fit and get all bent out of shape about it.

[Firebirdjones]

Originally Posted by tucsonjwt

I don't know how you get away with it. In Tucson, all vehicles newer than 1967 are checked for factory emissions - my 83 C20 gets frequent emissions anal exam most years. I was told by DMV that historic plates don't exempt you from emissions rules. I don't know about horse power, but my 73 454 C20 got about the same mpg as my smog laden 83 454 C20 9-11 city, 13-14 hwy.

Someone at the DMV wasn't being completely truthfull with you (they didn't explain it completely ). And that's probably in their best interest that the less people know, the better.

You need the historical plate, AND collector insurance, then you are exempt. You can look it up, it's in the books. Several buddies of mine down there are doing it with classic cars.

Now trying to get that done on a square body truck may be tricky. Depends on whether you find a collector insurance company that views your truck as collectable. The tags are the easy part.

I believe the thought process with the tags AND the insurance is that they now believe this is a vehicle seldom driven and has no impact on air quality, so they are exempt from testing. In order to pull this off, you also need to have a car that is registered and insured normally so you can say you have something else as your main transportation. Yet if you drove your classic tagged and insured vehicle all the time, or even just frequently 3-4 days a week, no one knows any better, but you didn't hear that from me.
The chance you take here is that if you are in an accident, your collector insurance might be wondering why you were driving on a Monday morning going to work rather than a car show or cruise inn, so there is a fine line here.

I've been down this road before many times

[tucsonjwt]

i guess it would not work out for me. My beater C20 would never qualify for collector car status just on bad looks alone. Plus, I normally only drive it to go to the dump or Home Depot or to use the dump bed to move rock or dirt.
Since the gas mileage for me would be the same with or without emissions equipment, I will stick with the cheap basic insurance and risk passing emissions every year - I passed every year but one in the past 10 years, and the one failure was fixed by professional adjustments on an engine analyzer. Not bad for original emissions on a 30 year old vehicle.

[SSC's76]

yeah I feel for you guys who have to pass inspections and smog tests here in Colorado they don't do it anymore anywhere they use to but don't. I have my truck registered as collectors but its just so I have a 5 year tag


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[Skunksmash]

I keep waiting for them to extend the emissions test for vehicles by another 10 years.

[Phil750]

=Firebirdjones;5731860]Someone at the DMV wasn't being completely truthfull with you (they didn't explain it completely ). And that's probably in their best interest that the less people know, the better.

You need the historical plate, AND collector insurance, then you are exempt. You can look it up, it's in the books. Several buddies of mine down there are doing it with classic cars.

Now trying to get that done on a square body truck may be tricky. Depends on whether you find a collector insurance company that views your truck as collectable. The tags are the easy part.

I believe the thought process with the tags AND the insurance is that they now believe this is a vehicle seldom driven and has no impact on air quality, so they are exempt from testing. In order to pull this off, you also need to have a car that is registered and insured normally so you can say you have something else as your main transportation. Yet if you drove your classic tagged and insured vehicle all the time, or even just frequently 3-4 days a week, no one knows any better, but you didn't hear that from me.
The chance you take here is that if you are in an accident, your collector insurance might be wondering why you were driving on a Monday morning going to work rather than a car show or cruise inn, so there is a fine line here.

I've been down this road before many times [/QUOTE]

Mr Firebird I was going over some old posts and I came across yours. Yes I did have it registered as a Classic. Mileage is about 3000 annually. No vintage plate required. I have my DAV plate. My insurance is with State Farm. My premium is 54. Every six months. I am retired so even the three thousand they give you is more than enough. My vehicle was egged two weeks ago. It's in the shop being repainted. When I get it back it's going to be sold. I hope this was some help. Phil

[74 stepside]

What year is the cut off for being smog exempt in AZ?