hey guys looking for some answers about dropping a lt-4 in my 94 Z-28

will pcm work or does it need be change out?

what about the wiring is it the same or does it need to be modify?

if there anything else that ya'll know about that maybe a concern hit me with it.

Thanks

 

If u are getting a lt4 engine make sure u get the PCM and the wireharness,it will make things alot easier in the long run.

 

Not nearly enough information provided. Is this a crate LT4? Rebuilt LT1 with LT4 parts? OBDI or OBDII PCM? The more information you provide the better.

 

If it's a stock LT4 and you have a stock 94 it'll drop in with no issues. You'll want to add a LT4 knock module to compensate for the noisier roller rockers.

If either aren't stock you'll have to make adjustments....

 

The "real" LT4 from a 96 Corvette will have two knock sensors, neither of which works with the 94 PCM. You will need the knock sensor out of a 93-95 LT1. The "real" LT4 will not have an EGR system, which may be a problem if you have a visual emissions inspection. An EGR from an LT1 can be installed for "visual", and does not have to work since the LT4 does not require EGR. The EGR code would have to be programmed out of the 94 PCM.

You will end up with a cam position sensor and an EVAP vacuum sensor and no place to connect them on the 94 harness, but they do not have to be used. You will need your 94 PCM flashed with the equivalent of an LT4 tune. The Corvette fuel rail connections will not be in the same place as the 94 LT1.

The front accessory mount and accessories from the LT4 will have to be replaced with the LT1 equvalent. You will need to adapt the LT4's vented Opti vent/vacuum harness to the 94 intake elbow.

And when you are all done, you will have less power than someone who had their stock LT1 heads ported, and installed a matching camshaft.

 

It should be noted you will have a LOT less power. Not just a little less. Cam only LT1s are known to put out more power than that did flywheel.
The LT4 stuff is NOT worthwhile, the only good parts about it is the valves which are nice and lite, and pistons make for a slight compression bump BUT the rods are not rebuildable and if the crank is ever turned down it losses all theoretical advantage it might have had, but since nobody breaks LT1 cranks unless something else takes it out that is pointless too.

The heads are just a bigger hole that doesn't actually work particularly well, the intake has SMALLER runners than your stock 94 intake.

Far as the computer stuff, just swap over your knock sensors though the OBD2 ones can be made to work with the 94pcm. The LT4 Knock module does not actually work right with an OBD1 pcm so don't bother.

If you use your accessory drive then you need to pull the timing cover and remove the reluctor or you need a 96-97 f-body crank hub.

Again though, all that said this is a very poor choice and you should have asked first IF this was worthwhile.

 

The Lt4 is a great engine choice, as is the lt1. Why he chooses to bash the lt4 every chance he gets is known only to him, (maybe an lt4 killed his brother). But don't let the haters deter you, especially if you can get it at a comparable price to an lt1 replacement engine. Then it's a no brainer.

 

If you actually look at RESULTS the only reason to buy an LT1 for the same price as an LT1 would be so you can flip the heads and recoup some money.

Everyone loves to say how great it is but REALITY doesn't back that up.

 

Yes you can get much better results by skipping the lt4 engine and upgrading your heads or a simple port and polish of them and a bigger cam at a much better price than it is to buy the lt4 engine. Plus there is a lot of stuff to change that will add up that much faster for the lt4. And i am not an lt4 hater just stating facts here.

 

IMO even in ported form most are far better off with LT1 heads than LT4.

I say that based on comparisons of similar cars with each, not the blind bench racing most folks do.

http://www.gmhightechperformance.com..._trans_am.html The car eventually went 9.88 with that setup.
http://www.gmhightechperformance.com...ns_am_lt1.html

Look at cam lift, weight, compression, shift points. The LT4 setup has a lot of advantage in those categories. The massive hole the LT4 heads offer allows the LT4 setup to turn more rpm with less duration BUT it doesn't look like that translates into actual performance.
Also note the owner of the LT4 setup TUNED THE LT1 setup.

Now this is approaching max effort I understand that but the faithful would have you believe that is where LT4s would shine.

The LT1 headed car has since gone to Trickflows and a small single plane intake and run like 9.4 still on low pump gas compatible compression.

Look at similarities in the cars, this is a useful comparison.

 

The original poster asked about installing an lt4 where an lt1 once was. Generally speaking, as close to a direct bolt in as you're gonna get other than another lt1 from the same year. If he wanted side by side comparisons of one to the other, there are plenty of sources online and otherwise for that material.

If this hobby was only about dollars spent vs. actual power made no one would be running an LT-anything.

 

Ill will second that comment! Also, it drives me nuts when people knock others for decisions about THEIR car. Positive input is one thing but come on. The hobby is about NOT following your fellow brethren...not stepping in line. If this guy wanted to install a Mercedes Benz 4.3L V8 from an AWD ML430, then we should gently advise against it and follow-up with some technical help if he decides go go with it.

MY CAR.

Charlie

 

Trouble is if nobody ever says what is a good and bad choice you just drive all the good options out because people continue believing in the bad ones.

Far as the close to direct swap thing the reasons for it not being that direct are YEAR differences not LT4 differences, other than the crank hub thing that is a Vette vs. f-body thing.

Far as not wanting a side by side comparison posted, admit it, you just don't like the truth.

 

You should change your screen name to Darwin, you cannot argue against evolution! We are not debating the aerodynamic drag coefficient of a lunar entry vehicle here, simply stating that there are multiple means to similar ends and it would be foolish to never explore them. Plainly stated, a stock LT4 platform is superior to a stock LT1 platform for a multitude of reasons besides the obvious ones like a more efficient intake, better heads, 4 bolt mains, full disassemble which included blueprinting/balancing, torque plate honing and 20% dyno tested! All of this allowed for 20 extra horses, Ill take that over a stock LT1 anyday! In-fact, I think it would have been a logical UPGRADE for ALL SS cars.

Anyway, back to the Darwin thing. The LT4 was an upgrade to an already proven architecture, a natural performance progression within a specific engine genus if you will. Denying what it truly is simply and unnecessarily makes you look like a cynic.

 

If the 94 Z28's engine is blown and he gets a great deal on the LT4, go for it. If his LT1 is in good shape and he's going to have to buy a LT4 probably not such a great deal.

It was stated that it was a fairly simple swap with a few hitches, then it was suggested that for the same money or less he could upgrade a decent running LT1 and be better off power wise compared to just swapping in the LT4 with less effort.

If that's what the op wants to do, more power to him, but I think most people from the comments above are just saying that he shouldn't buy into the myth that is the LT4. Not knocking them, but a stock LT1 to stock LT4 swap isn't going to be a huge difference.