Abbacabba

I'm thinking about putting a LS1 or LS6 (what ever I can find) in my 81 corvette.

I'm noticing that most of the conversions done don't bother usinging the emissions systems and I don't see any one say they installed O2 sensors in their older vehicles.

What impact does this have on the engines performance? I was always under the impression that having a working emissions and O2 sensor(s) helped these engines fuel consumption. <-- whats the real story?



Also this will most likely be a daily driver, so I'm not wanting to dump lots of $$ into the engine for more HP, but what are some good items to look at replacing while I have the engine out of the car? I'd try to stay <1000 on upgrades, but something that had a good impact on performance or fuel efficiency might be worth it.

E36LUVA

The engine software is usually altered or flashed to accomodate what ever swap is being done like disabling the immobiliser, the speed govenor, the downstream oxy sensors etc. These changes shouldn't affect the fuel economy. If these changes aren't done then the engines would never run right. I believe the hand held programmers are capable of doing this.

Stu Cool

iTrader: (13)

I think most folks keep the pre-cat set of O2 sensors and eliminate the rear set. That's what I did. That way the ECM has those readings to adjust the misxture. I did get rid of the rest of the emissions except for the PCV.

Easy changes to make would be an LS6 manifold if your motor does not already have one, cam upgrade, cooler thermostat, coolant by pass for the throttle body, free flowing dual exhaust, but you may have that already. I changed to LS6 Valve springs, mostly because I found a cheap set, and also upgraded to the LS6 style PCV, mostly to get rid of some ugly plumbing but also because it is supposed to be reduce oil consumption. If you are going automatic, a 2800-3000 stall torque converter makes a huge difference.

Hope that helps

Pat

Edit: I get 25 highway mpg. I have not tried it at the track, will do that next year after I finish my rear suspension update. I am expecting low 13s, possibly high 12s. My vehicle weight is 3400 pounds.

bczee

iTrader: (12)

What state do you live in.. for the question of SMOG and Emissions Laws and what you need to pass it...

That will be on of the question on your swap for removal or having to pass visual inspection on the equipement. If none for your car/year.. you can remove anything that is not really needed and have good tune put into the PCM and Flash out any codes not needed.

Good luck.. we well be watching..!

Abbacabba

I'm in a non-testing county in TN.

I've also got a set of hooker side-pipes that I'll be modifying to mount up to the LS1(if I go this way). If the O2 sensors are needed or will help the fuel economy I'd just make some "hidden" mounts in the side pipe collector for them.

nitrovette

iTrader: (13)

i modified my hooker sidepipes and mounted front 02's in them and eliminated the rears.Everything works fine,runs great,also added a ls6 intake and eliminated all emissions.As fars as mpg id say somewhere around 18 mpg is average when im not beating on it,thats also with a 700r4 2400 stall and 3.70 gears.

bczee

iTrader: (12)

cool.. wish I was in a non-testing state !

You will only need the pre-Cat O2 sensor.. the post-Cat is just to make sure the Cat is doing it's job and to have the PCM make adjustements to the mixture to meet emissions..

GM does market the engine Heard Flanges that you might be able to used to modify your Headers. Should be too much of a task for someone who is a good fab and welder.

I have a set of those flanges that I was going to use.. but didn't, if your interested in them. I will sell them at a small lost to me (got them from GMPARTSDIRECT). PM me and we can work a deal..

nitrovette

iTrader: (13)

Heres a pic of my gm flanges i used on my hooker sidepipes,took some time cutting and fitting then welded them up.

bczee

iTrader: (12)

Looks good.. just send them out for a good Coating job now !

where did u put the O2 ?

70 LS1

iTrader: (1)

I'm using O2's as well. You can program them out, but why? Like you said they are there for a reason.

Stu Cool had a good list of basic cheap mods. If you don't do a cam while the motor is out, you will kick yourself for it later. Trust me.

G-Body

iTrader: (4)

+1 on that

nitrovette

iTrader: (13)

+2 on that do a cam.

nitrovette

iTrader: (13)

right before the side tubes,sideways facing the frame,hidden ,cant be seen.There also black sidepipes so i just painted them and wrapped them with header wrap.
http://rides.webshots.com/photo/1175...52841409zPTezC

Abbacabba

Any suggested cam?

What about porting the heads? I'm pretty good with my dremel and grinder bits.

Do the intake and exhaust ports already match perfectly with the ports on the heads? Do they already match the gasket(s)? Thats always an easy grind and blend job that has been shown to help.

stealth71

iTrader: (15)

What's the goal for fuel economy? What is your HP goal? Are you planning auto or 6 speed manual? What rear gears? All this will be needed to plan a cam and head improvements. Bigger cam/heads = more air = more fuel. Guys are putting down over 400rwhp and getting over 20mpg on the highway, but the entire combo will determine what you come up with.

For about $800 you can do cam, oil pump, pushrods, spring kit, gaskets and bolts necessary. This will get you close to 400rwhp depending on how radical a cam you choose.

s10-den

what does porting the oil pump do?I see alot of people are porting the oil pump.To get MORE oil flow?

mullenh

iTrader: (1)

i think everyone with fuel injection and a computer has an o2 sensor. it is an advantage. it is the after cat o2 that is deleted. as for the rest of the emissions stuf yea it is gone, no air pump, no egr.
if you are doing an a4 at least change the stall converter if not the cam