Last year I bought my 40k mile '96 LT4 used with almost no history and thought it was mostly stock, but I have been sneaking up on an opinion that it might have a non stock cam. Possibly an LT4 hotcam since they seem to be so popular and have good driveability with better performance. I also wonder because it did have some changes from stock like a Borla catback and a SPEC flywheel and clutch, so maybe they did other stuff too?

The reason I have begun wondering is that a friend also has a '96 CE LT4 and when on cruise control at 60 mph on flat road his runs about 30 mpg and mine runs about 28 mpg.

I also think mine runs stronger. Today I was playing and tried out an old accelerometer device (similar to a g-tech) and was surprised at the results. I got mostly 12.8's at 115 to 117 mph (on a closed road of course). In the past my accelerometer has been pretty close to some cars I ran at the track, but I haven't done that in a while and not really sure how accurate it is, but I like those numbers and hope they are not too optimistic.

I thought the car was stock, but some things don't add up to me, like even though it idles smoothly, it pulls more than expected with slightly worse mileage.

I may break down and take a valve cover off and use a dial indicator for measuring the valve lift, but I am lazy and don't really want to do that while the car is running good. And even then I might be able to confirm a different cam, but still wouldn't know which one.

Other than taking the engine apart, is there any good way to tell what cam is in it? I can't think of a way to tell for sure.

Anyone with an LT4 (with or without mods) have any comparison 1/4 miles or mpg, especially if before and after mods.

Sorry for the rambling, but just some idle thoughts and curiosity.

 

Take it to a dyno...other wise you need to get the dial indicator out.

12.8/117 is pretty strong. The trap tells the story, although those devices that you used show a slightly higher trap than you'd see at a drag track. Figure 114-115 at a real track? That's LS2 territory.

 

What rear gears do you have?

 

I don't think some of the internals on my 84 are stock, previous owner said heads were done etc blablabla the cam cover isn't stock, who knows. Not messing with something that works fine until it breaks!

 

The dial indicator may confirm a non stock cam, but it still won't tell me what cam it is.

I probably won't go to a dyno, but I may have to take it to a track (that is a lot more fun too).

Although seat of the pants is not accurate, I have a C5 with a slightly modded LS1 (Vararam, FAST, LG longtubes, tune) that should be about even with an LS2 and my '96 feels every bit as strong. Feel can deceiving, but it is a fun car to drive.

Seat of the pants is another reason I think it might have a different cam. I keep hearing that an LT4 and an LT1 run the same until higher rpm where an LT4 runs harder. Unless I am racing I usually only go up to about 5k. However, my '96 LT4 runs harder than my '95 LT1 6M from low rpm up to about 5k rpm too.


I have the stock 3.45 ratio.


I didn't get any info from the previous owner, but like you, I am not wanting to take it apart while it is running good.

 

I bet you could; measure lift intake & exhaust. Compare w/the standard Hot Cam specs. If it's a match...that is pretty strong evidence that you found your cam. With a degree wheel you'd get duration but that is a lot more work.



That is the truth. When I first got my LT1 running and still had my C6....I mean, the C4 was as fast as the C6. IT WAS. SOTP. In reality, the C6 was a solid 1 second and 10 mph faster at the drag track.

 

When I get time, I might have to pull a valve cover and check. That could at least verify it is not stock and if I'm lucky maybe match to a common one.

I think I really need to just go to the track and see what I get. I would like to believe the numbers I got, but I am skeptical. They seem too good.

I have done a few searches for LT4 1/4 miles with and without mods, and I see so much variation that I don't know what to believe. My best guess from the searches is for a stock LT4 to be running low to mid 13's and then it becomes more confusing on how much better with mods since so many have multiple mods and the mods are frequently different.

From the searches I am guessing a stock LT4 with a cam like the hotcam might be high 12's to low 13's. I would like to hear from people with a first hand experience what the before and after times were when doing a mild cam on an LT1 or LT4.

 

What do your ears tell you?

First time I heard a hotcam, the bubba-la-bubba-la made me wish I'd opted for more exhaust duration on my custom grind. A hotcam doesn't SOUND like a stock cam.

 

It sounds pretty smooth.

I have built quite a few motors with more aggressive cams and to me this sounds like stock or nearly stock.

I like the sound of a wilder cam too.

 

I have the hot cam in my LT4 convertible and while I don't have before results I did take it to the 1/4 mile track in Pueblo CO last year so I have some after results. The actual elevation there is 4900 feet, and the air wasn't great that night so the DA was 6700 feet. My best run was 14.15 at just under 105 mph with a 2.3 second 60. I had a little trouble with wheel spin off the line but was pretty happy with the mph at the top end. I was running quicker and faster than both a stock C5 as well as an LS1 GTO. The dragtimes.com DA calculator says that should equate to a 12.959 at 114 at sea level. For reference a Challenger Hellcat was running 12.7 that night, don't recall his mph.

 

An LT4 convertible is pretty nice and not too common.

It sounds like a fun day at the track. The compensated time/speed of 12.959/114 is pretty good too. What I could find in searches there seem to be a lot of LT4's with a hotcam in the high 12's, so your car matches that pretty close.