LT1 to LT4 conversion and Tuning

if i'm not mistaken, the lt4 conversion kit comes with everything you need except getting the pcm reprogrammed. the only thing that you REALLY need with the conversion is a larger throttle body. the 52mm is the best in my opinion, i've heard of the 58mm being overkill and actually losing hp due to the loss in velocity. a bigger mass air flow sensor is a good idea too. seems like you got everything together, just get out there and do it. for the trans, i'd just get a MILD shift kit. try transgo or b&m. i'd leave the cats alone too. what kind of catback? hopefully not flowmaster! those sound terrible on f-bodys because of the transverse muffler. borla sounds freakin awsome. oh yeah, when you get the pcm reprogrammed (dunno where to get it done) ask if the lt4 knock module was installed. if not, get one off of ebay for like $20 and install it yourself. really simple and really effective at high rpms. good luck

jack love TA's but aint got the money drive a 00 v6 firebird, next best thing.

except getting the pcm reprogrammed. the only thing that you REALLY need

conversion?

Not sure about this, but you may want to research the opti-spark mounting with the new cam. There may be differences. Either way, since you will have the motor down this far, you may consider retrofitting to the non-vented opti-spark anyhow.

Steve...

Why would you change perfectly good $500 (at least each from OEM) cats if there's nothing wrong with them?

Sure a high flow version might "net" you some HP, but the gain isn't enough to toss out the OEM ones unless they are truly bad. And if they are, something has caused that.

I have the original converters on my 20+ year old GM cars! Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 27k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going....

Based on what functional reason?

(Newsflash: You have none :) ).

I have the original cat in my '84 Oldsmobile and it flows and passes emissions as good as 1984 when it was put on the car!

My 1980 Trans Am using the standing idle test easily passed for new cars ten years newer than it (with the original cat :) ).

Fact: The converter lasts the life of the car if the emission system is properly maintained.

Fact: No need to change it unless clogged.

Fact: If it's clogged or restricted, you have a engine management/control issue that needs rectifying or the new cat will be kaput in no time.

Ask any muffler shop that does cats how many warranties they've refused when a customer with a bad running vehicle shows up a month later saying his cat is bad when the invoice stated, "Needs a tuneup".

Or how many refuse to do the job unless the customer gets the vehicle in tune.

Plenty :). Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 27k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going....

Joe:

I change a good number of factory installed catalectic converters. Especially on GM FWD cars.

#1 reason on GM FWD cars: Mechanical Damage. That is either a lose core, rusted off A.I.R. tube, or Damaged shell. With Honey comb style converters, if the core is broken free (lose) it will fail, and start sending material out the tail pipe(s).

#1 reason on GM RWD cars and trucks: Failure of emissions tests, usually something else triggered converter to die.

Here in Ohio they do a quick visual inspection of the catalectic converter with a mirror. If the A.I.R. tube is rusted off, or improperly repaired the car fails right there. If the shell looks damaged, it fails. If they shell has a rust hole thru a external shield, it fails. Often those cats are still good, yet they have to be replaced. New aftermarket cats are not very expensive. I don't think I know of anyone outside of new car dealerships that install O.E.M. units.

As for the guy that keeps saying B.S. about 100,000 miles, I have seen cars with 300,000 on the original cats. So your an idiot. You probably blame every problem on emissions controls, and have no real idea what the cause is.

Charles

Do you use 87 octane or regularly use 93?

What the hell difference does that make ????????????????????????

Most 1971-later through the 1980's cars are made to run on 87 octane.

Hell, my 335HP/480ft lbs torque 455HO was designed for 87 octane.

Ummm, I'd love to hear the explanation on this one. Where on earth do you get your data? LOL.

My neighbor owns a 2003 Acura, a $50,000 automobile. The manual for that vehicle explicitly states that anything beyond 87 octane in the vehicle is simply a waste of money, the vehicle was made for 87 octane.

I don't think he'll be changing the catalytic converter any time soon due to him using 87 octane.

Again, I'll say it again. Emission system maintenance is the key to parts longevity. What Charles described were reasons why they are replaced such as lack of maintenance, physical damage, rust, etc.

THOSE are valid reason to change a cat, not mileage. LOL.

Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 27k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going....