diff between 95 caprice lt1 vs ws6 lt1 please help

[burn em down]

I have a 97 trans am ws6 6 speed with a donor 95 caprice lt1 bottom end.

The car just dose not seem to have the power it should (can not spin wheels in 1st) and barely chirp second gear.

heres the low down

95 caprice lower end with low miles on it (said by prev owner)

Stock ws6 aluminum heads and the intake manifold that came on the ws6

Only thing that is catching my eye for power loss is that they rated the caprice lt1 at 265hp and rated the ws6 at 305hp....what was such a dramatic change to give it that much more power. The lower end still has the caprice cam in it and i was on another forum and a member said the cam was really close to the ws6 cam? Is this true or do i need to be swapping the stock ws6 cam in the motor (i have the orginal motor).


Any advice would be great, the car just dose not have power.



Parts ive replaced in past 200 miles

Opti cap, rotor
New intank oem pump
Fuel pressure regulator (just being safe)
Gutted the cats last weekend

[xDetroitMetalx]

If I remember right B-Body cams are different than F-Body cams.... Did you swap cams?

[burn em down]

no sir i have not, thats why i was posting this. i think the cam and heads may have been the diff in power levels. seeing that the cam from the caprice is still in the motor with the ws6 heads and intake manifold may be the power loss im trying to describe... i mean the car has damn near no power i can drop the clutch at 3k and it falls on its face with no wheel spin......... sadly i think cams have to be changed out wish the prev owner did it while both motors were out!

[xDetroitMetalx]

I also know there are "baby" LT1s... They aren't exactly 350 ci and are often confused for LT1s. Sadly I don't know what cars had these motors or how to distinguish the differences in them as I've never really cared.

[shanesmith]

I'm betting what you have is an L99 4.3. they're nearly identical to an LT1, however they generate much lower numbers. 200hp/245tq. If it were a caprice Lt1 you would have no issues breaking the tires loose. the 330 lbs ft of torque is still there. the lower horsepower rating is due to cast iron heads and a cam profile designed for more torque at the bottom end. you might wanna see what you can find out. I'll bet someone passed an L99 off as an Lt1 at some point. it happens faily often.

[wdmickjr]

hey.
not only was can but iron heads B body are 10:1.

The iron heads are the same as Vortec L31 w/o reverse flow. LT1 block has a casting number ***327

[cocobolo95]

Burn em down did state he was using the aluminum heads from a lt1 f-body. Look at your engine block it will have 327 and 5.7 on an lt1 block. If you don't have those on the block then you do have a l99 4.3. If you do have the lt1 engine, there is always the possibility of something being wrong with it. Ignition and/or fuel problems, as well as, sensor problems, can make the lt1 fall on it's face. The first thing after checking which engine you have, is to hook car up to a scanner that is capable of reading real time sensor data, and do a running sensor scan, in addition to a code scan as not all codes light the ses. If you don't have a clue to what the sensor data means, pm me with your e-mail address and I'll send you the pdf file "sensor readings and what they mean".

[95 Firehawk]

Originally Posted by burn em down

Only thing that is catching my eye for power loss is that they rated the caprice lt1 at 265hp and rated the ws6 at 305hp....what was such a dramatic change to give it that much more power. The lower end still has the caprice cam in it and i was on another forum and a member said the cam was really close to the ws6 cam?

The 96-97 F-body LT1 was rated at 285hp, 25 more hp than the B-body 's at 260hp. The WS6 was rated at 305hp, gaining the 20hp from the ram-air intake. The lower power rating was from the smaller cam...

F-body: 202/207 0.450/0.460 lift 116 LSA
B-body: 191/196 0.418/0.430 lift 111 LSA

...and lower compression heads of 10.1:1.

I would certainly put the original cam back in, or better yet, upgrade to something a bit bigger.

Originally Posted by shanesmith

I'm betting what you have is an L99 4.3.

I'm not sure, but he said he used his original F-body LT1 heads, which have larger valves that I doubt would fit the 3.736" bore of the L99 without further modification.

[burn em down]

thank you everyone for responding to this. i did run numbers off the block of the lt1 in my car and it comes back to caprice/firebird/camaro lt1 so im safe on that part no baby lt1 here thankfully lol.

I will get it hooked to a scanner again and see what it reads out again.
Any ideas of sensors that could throw the car on its face?

[xDetroitMetalx]

There are a few, just gotta scan it and report back.

I'm still thinking it's the smaller cam. Just think, for a few hundred bucks you could upgrade to an LT4 hot cam since you might take it out anyway!

[KW Baraka]

Originally Posted by 95 Firehawk

The 96-97 F-body LT1 was rated at 285hp, 25 more hp than the B-body 's at 260hp............and lower compression heads of 10.1:1.......

The Caprice LT1 engine with the aluminum heads will come in at 10.4:1 CR if you use a F-body spec head gasket.



Burn Em......there's a chance that the Caprice engine is just plain tired. I'd do a compression check on the cylinders before doing anything else to the engine.

Also......do you do all the appropriate parts swaps from the old to the 'new' engine? I ask because your car is OBD-II and the engine came out of an OBD-I car.....

KW

[burn em down]

well here we go this is what i know as of todays snap on blue point scan-

Every thing was showing normal limits

tps checked out
maf checked out
o2's had high readings but im not worried about them (gutted cats)
spark advance was a little odd i thought about 18-20 idle then as high as 48 at about 5k revving in nutural.
Knock sensor show'd no sign of putting timing at any point


I changed my icm with a known to be good one as well, tried unplugging just about anything you can unplug to see if any change in power was made and nothing happend.

I do not think the motor is tired it dose not burn oil, tick, smoke, or anything of that matter, sounds real strong when revving and driving just no power. leads me to thinking smaller cam is my issue.

as of right now tonight im going to start tearing down the motor and change the cams back the way it should have been when the prev owner changed it. (woulda took just a few mins to do while both motors were out, now its gona take me all weekend).

Anyone have any advice for me before starting this super fun task lol

[burn em down]

i forgot to mention it did have missfires on every cylinder today showing from the scanner. sorry i forgot to mention that above!

[shanesmith]

I'm not sure, but he said he used his original F-body LT1 heads, which have larger valves that I doubt would fit the 3.736" bore of the L99 without further modification.[/QUOTE]

Ya know what? I completely missed that. I've just seen someone get "shafted" by another passing an L99 off as an Lt1, and seen many sales ad's doing the same. At one time someone tried to sell me an L99 car as an Lt1, luckily I had the foresight to check the vin.

[shanesmith]

Originally Posted by burn em down

i forgot to mention it did have missfires on every cylinder today showing from the scanner. sorry i forgot to mention that above!

Could be the opti spark. I've never personally had any issues, but i know people who have.also,I'm not convinced the cam is the issue. Even with the caprice cam, the 330 lbs ft of torque is still there, so you would still have no issues "breakin 'em loose." Of course, a bigger bumpstick isn't a bad idea at all.