lsfanatic

I recently purchased a 2000 C5 vette which the previous owner had swapped (what he said was) a LS2 into the car. I was looking around under the hood the other day and noticed it has 317 heads.

I know they are basically the same as the 243 heads that came on LS2s but with a larger combustion chamber that lowers compression. These are the same heads that are on the LQ4 in my truck.

I know it is a gen IV block because he had to move the knock sensors, and I am pretty sure its still an aluminum block but I never actually checked. My question to you guys is what motor do you think I actually have? As far as I know 317s only came on the Gen III 6.0L truck motors (LQ4 and LQ9), but maybe there is something else? My only other though is maybe he swapped the heads but I don't know why anyone would swap to lower CR. I am going to try and get the serial number off the block casting at some point also. Thanks for any input.

Darth_V8r

iTrader: (4)

Only reason I can think to swap on a 317 head is if I was planning to boost. Previous owner might have paid someone to swap it and not known the difference?

lsfanatic

The guy I bought it from owned a shop and it was done by his guys. He said he has a few LS crazy techs that talked him into doing it. I emailed the guy I bought it from to see if he can dig up the VIN from the vehicle the motor came out of.

redtan

iTrader: (5)

Do you actually know what was done to the 317 heads? Some people use those as they can be welded and actually achieve smaller combustion chambers without much milling, so he could've done that.

Or he had some high dollar heads on there before that he swapped out for some cheapos right before selling the car as those fit the bill.

lsfanatic

I guess that is a possibility that he modified the heads. I don't know one way or the other.

Just from talking to him I wouldn't think he would swap the heads just to sell the car, or really even have better heads on before. Mostly because he said he used the car primarily just for driving around with his wife. lol

96capricemgr

iTrader: (1)

Professional just means gets paid to do something, has nothing to do with knowledge.

thunderstruck507

iTrader: (18)

check for an iron block...it will take you 10 seconds with a magnet

my guess is you have an lq4 or at best an lq9....not an ls2

lsfanatic

That is what I am starting to think. I will check this weekend, I am out of town currently

dr_whigham

iTrader: (49)

Mine as well. Surprised it took 7 replies for that to come up.

whatsa347

iTrader: (6)

He probably meant iron "Ls2" which is what the jackasses on Craigslist call Lq4 and Lq9 motors.

lsfanatic

The guy I bought the car from included the motor he took out, said it is fine. I have yet to thoroughly check it out but he did keep it for a few years so I can't really see someone storing a motor for that long that is shot...

If the old motor is actually good, it would make absolutely no sense to switch to a LQ4 or LQ9 for the same/reduction in HP and an extra 80-90 pounds over the front end. So either the guy is dense or something else weird is going on

thunderstruck507

iTrader: (18)

I agree with that. Unless those heads are highly worked over it makes even less sense to swap those onto a ls2 shortblock as the loss of compression would lower power negating the entire point of the swap. Especially when you factor in the swap parts to go gen IV and the need for a tune (which may or may not be done).

But at the same time some people are just under the impression more cubes = drastically more power which is not the case.

lsfanatic

Yeah it hasn't been tuned. Which spawned this other thread of mine:

https://ls1tech.com/forums/pcm-diagn...low-input.html

thunderstruck507

iTrader: (18)

Tough call on how to advise you to proceed.

If it were me and my budget allowed I would be looking into getting some CNC ported 243s then pull the 317 heads and see what's up with them. Once you know what you have you could sell them and install the 243s before taking it to be tuned.

Is it cammed at all?

lsfanatic

No cam. I will check about the iron block and possibly try and pull the serial number off the block to get a definite answer.

Depending on what I find I might just go that route. At least swapping heads on a vette with the motor in the car is easier then the 4th gens.

brandon6.0

iTrader: (32)

My geuss is the old motor was hurt and he performed a cheap 6.0 swap which is probably a lq9. U can pull the numbers on the front of block near the head and find the year of it. Only difference between a lq9 and ls2 is weight, compression, and cost. I say swap a cam and run it!!

lsfanatic

Depending on what I find this weekend I may just go that route.

Do you have a picture of where the number is on the front of the block? I was only aware of a block serial number on the back against the firewall

thunderstruck507

iTrader: (18)

Personally I would prefer not to have the extra 100lbs on the nose of a Corvette as it's detrimental to handling.

If it turns out to be iron I would look at either rebuilding the aluminum engine you got with the car and swapping it back in with some power goodies or selling both engines for some other aluminum block crate engine.

Depends on OP's goals, budget, and how he intends to use the car what is best for him.

ahritchie

iTrader: (1)

Ditto, it's going to mess up the perfect 50/50 balanced weight distribution C5s had stock and increase understeer . Not to mention reduce resale if you ever sell it.

lsfanatic

That is a good point, I have kind of been thinking how much is 100 lbs in the grand scheme but I guess it is more detrimental than I think.

I eventually want to do autocross every now and then and maybe some road course events, so handling will be a concern.