Well, here is the deal. I just bought a LT1 out of a 94 Caprice. I know the obvious differences like the heads, maf sensor, air intake and such. The guy just had his LT1 replaced with one out of a Trans Am(he said it was a 96 LT4 but I have my doubts).

I was wondering what some of the differences were so I could tell what stuff I ended up with. I measured the MAF and I have the 3.5" which is off of the f body right? It also still had a tag hanging off of it that labled it as a complete engine assembly out of a 95 trans am with Vin code P. Is P the LT1 or LT4. I am guessing that it is a LT1.

Anyway, how can I tell which vehicle that my accessories, computer and wiring are out of. Also what differences are there between the 2 cars?

Thanks

Ben

 

I'm pretty sure the f-bodys had a 4 inch diameter maf and the b-bodys a 3.5 inch diameter one.

I know what my 95 caprice wiring harness looks like but I haven't seen an f-body one.

 

Actually, what I have read on the impala forums I have visited is that the impala has a 3" and the F body has a 3.5". That would it would make since that the 3.5 that I have is off of a f body because it still has the tag on it from the junk yard that says it is from a 95 Trans Am.

Ben

 

Yea, that is probably it. I should go out and measure mine. All I was completely sure of was there is a half inch difference.

 

Is ther another 350 that came out of the Caprice? This guy told me that he's got one, but it's not an LT1, the LT1's have aluminum heads, and this one didn't.

 

If it is from 93 or earlier it is not a LT1. If it is 94-96 it can be either a LT1 or a 4.3 liter V8 which also looks like a LT1. If it is out of a 94-96 and it is 5.7 Liters it is an LT1. Caprice LT1's had Iron heads. The Iron heads from Impala's and Caprice's actually flow better than Aluminum heads but have 10.5:1 compression and the Iron heads only have 10:1 compression.

Ben

 

Is it just me, or didn't the LT4 only come with the Vette, not the F-Body? I may be wrong tho. Is a '96 350 out of a Caprice an LT1? Is it worth modding? Or evern buying??

 

I think that there were a few LT4's put in either 1 or 2 years of f-bodies but not many.

I hope the LT1's out of the Impala's are worth modding cause thats what I got lol. Yes the one out of a 96 would be a LT1. I would rather have a 94 or 95 if it was out of a caprice or impala or a 95 out of an f body or Vette if you are so Lucky.

My reasoning is that if you do much research on LT1's you will find that he optispark is a common concern. They are what replaces the distributer in a sence. They will cost you around 200(more if you dont shop around, I think the retail price is 600+). The 95 and up f bodies have an improved version of the optispark. The caprice and impala got it in 94. The newer version is vented to help prevent corosion.

The reason I wouldnt go with a 96 or 97 is because they are OBDII. A tuned obdI computer will make 5-7 more hp than a tuned OBDII. Another benifit of OBDI is that you only have 2 oxygen sensors instead of 4. You dont have to deal with the after cat 02 sensors. I guess that you can convert obdI to obdII. You can get the conversion pcm at www.pcmforless.com for about 275.

The only real downfall of the Iron headed motor is the weight. I think that the Iron heads add about 50 lbs, but the motor will make as much or more power as the f body motor with equal cams and upgrades. In stock form the Iron headed cars had smaller cams and made more low end torque but less power. With the Iron headed motors you automatically get the more dependable opti spark, and better flowing heads, but gain a little weight. It is up to you. If you plan on porting the heads you most likely loose the flow benifit of the Iron heads. I believe both sets of heads can be ported to flow about the same numbers, but the aluminum heads suffer more from core shift and arent always as uniform from cylinder to cylinder.

Oh, and as mentioned above the f body and vettes got 3.5" MAF sensors and the B bodies got 3", but I have read that the 3" MAF doesnt really become a restriction until 400+hp.

I got my LT1 complete for 600, and it has the f body MAF so I dont have to worry about that. The reason for my thread though was to see if anyone could tell me how to tell if my harness and accessories are from a f body or impala which I still havent figured out.

Ben

 

I have an article that is all about the LT1 and it stated that all 5.7L LT1's were 10.5:1 compression. It also talked about the differences in the heads, cam, and some other things.
The Baby LT1 (4.3) might have had the lower compression.

The differences in the Caprice and F-body are:
MAF
Waterpump
PCM Location
Heads
Cam
and I think that's it.
The Caprice harness is perfect for our cars since it routes the PCM towards the drivers side battery tray, this is where I plan on mounting my PCM. My air intake goes to the pass side battery tray while my battery sits neatly in the back.

 

Well, I put the harness on my motor, and it appears that it is the f body harness by computer location. I had also read about the different computer locations, but it is kind of hard to tell where it is going put the compuer at when it is laying in a wad in a large rubbermaid container.

What is different about the water pump? Also, if you go over to www.impalassforum.com or even www.camaroz28.com on the LT1 board they will tell you that the compression on the Iron headed LT1's is only 10:1 not 10.5:1.

 

Well, hopefully the compression change is only due to the heads, I got rid of the Iron ones and got a set off of a Corvette.
On the waterpumps, the F-body one has a pipe on the front, if you look at my LT1 I posted, there is a shiny round spot on the right front of the pump, on the f-body, there is a tube coming out there. Also, if you look at the green hose, the pipe behind it coming from the waterpump is shaped different on the f-body.
I've got both pumps in the garage, I'll take some pictures of them and show you in detail the little differences.

 

The difference in compression is due to the heads. The aluminum are 58 cc and I believe that the Iron are 62 or maybe 64. I am going to use the Iron heads because they flow more stock and I will do some porting on them. I should be able to get around 250 cfm intake out of them. You can also fit larger valves in the Iron ones.

Ben