Bought a 1993 Z28 with a blown motor. I have a buddy that owns a machine shop and rebuilds motors for a living, so my options are endless. The car has a LT4 hot cam, GM performance roller rockers, upgraded injectors, MSD optispark, and hooker full length headers, cat delete. Car had no engine codes, custom tune. Had a stock bore and stock compression ratio before lower end noise (spun rod bearing).

1) How big of a pain would it be to upgrade to the 1994 and newer mass air system? The engine wiring harnesses and MAF intake setups seem pretty cheap. Is the benefit worth it?

2) If I leave the same cam, but have to go 30 over to clean up the block, will I need to reprogram the ECU?

3) If I leave the same cam, go 30 over, and up the compression a mild amount (from 10.5:1 to 11:1) am I going to have to re-tune?

4) If I do end up having to buy new pistons ($200) and new rods ($200) and turn the crank ($100) would I be better off just buying a cheap eagle 383 kit ($800) that comes with bearings?

5) What is the cost of reprogramming the computer? Is there any place that anyone recommends on here to send it out, or better to find someone to tune it in the car, running?

Are the upgrades worth it, or am I better off putting it back together the way it was and enjoy it?

 

Well you can put a lot more into it than the car is worth real quick, with a '93 I think I'd just put it back the way it was and enjoy it.
I had a '93 and enjoyed it quite a bit but sold it with 222,000 miles on the clock (had 176K when I got it) and stepped up to a fairly low mile (86K) LS1 car before going mod happy.
Of course I'm into it more than it's worth now too (lol) but not near as far upside down as I would have been with the '93 and the LS1 is just faster dollar for dollar not to mention more reliable.
Just my 2cts.

 

1)Not worth it. Believe it or not, a lot of people switch to the '93 set up because speed density is more forgiving and easier to tune.

2)Nope.

3) No but in this instance, you could. It would net you a mild boost, but not enough to notice. If it's not already tuned, you can have it tuned specifically for 93 octane.

4)Personally no. You would be better off matching your crank, rods, and pistons separately, but it also depends on what you want. Yes, the Eagle and the Scat kits are nice for someone who wants a quick, cheap, all around build, but researching and choosing for what you're after is personally the way I do it. The saying goes, cheap, fast, or reliable. You can only choose two.

5)LT1 PCM Tuning - Welcome! Can't remember what it cost, but I was extremely happy with the service. He'll do a basic tune based off of what you want and what you have done to the car and then he'll do one free retune for you if you send him a recording of the datalog with you driving the car. '93 is the only year for the 4th gen that isn't flash based, so you will need to buy a extra "blank" chip for the retune and have access to a laptop if you don't want to send the computer back to him.

Everything is based off of what you want from the car. Your best bet is to answer that on a piece of paper, what you're willing to spend (if money is an issue), and then organizing parts and services from there. It can add up real quick if you're not prepared and start without a plan.

 

Thanks for the replies!


This is more or less what I'm worried about. The car has 63,000 original miles and it shows. The interior is mint, as is the exterior, aside from three quarter sized door dings. The underneath of the car is cleaner than most cars 2008 and newer. It's truly a beautiful car.

The former owner was a middle age man, that bought the car nearly new, and after owning the car for 15+ years, he decided to hop it up. He did the cam, MSD opti, MSD coil, injectors, roller rockers, lt4 cam, headers, etc. and messed something up along the way. He blew up the motor the first 500 miles after putting it back together and putting $2-$3k into it. I can have the motor rebuilt better than stock (roller timing chain, forged connecting rods, hyperutectic pistons) for around $550. I paid $1400 for the car as-is, with the blown motor with all of the performance upgrades mentioned above. I can have an upgraded, zero rust, 63k mile, 93Z with a reliable 330-350HP, for around $2000-$2200 total into it. I would guess because of the miles and condition the car should be worth around $4-$6k to the right buyer. People are trying to talk me into LSing it (LS THE WORLD!), but if I do that, I'll have an easy $2-$3k more into it, $4500ish total, and it will only be worth $6-$7k at best. It's a losing proposition, IMO.


Thanks for the reply, especially concerning the stroker kit. It's only a couple hundred more than an upgraded stock lower, but I'm guessing it'll net me 50HP at best, and cause a bunch of headache (throw off the tune, make it harder to tune, throw off the cam [more cubes should be paired with a bigger cam], etc.), not to mention shorter piston skirts, reliability concerns, etc. Looks like an upgrade stock rebuild it is!

 

If you stroke it, then you'd have to retune, just a clean up on the bores wouldn't require it. Don't LS it. The LS is a great engine, but it is a bigger PITA to install then some think.

Also, with a stroker, depending on the rod/piston you may need to clearance the block.

As far as I know though, no one makes a roller timing chain for the LT1. Which isn't a big deal, believe it or not, the OE timing chain is a pretty stout set up.

Also, you didn't mention whether this was an auto or manual. If an auto, a torque converter matched to whatever cam you get will really help, as will a quality shift kit. Manual, is a little easier, just need a better clutch and be easy on the rear, they are the weak link.