caprice lt1 vs. Camaro lt1

[stepho]

Correct me if I am wrong but the lt1 found in the caprice is exactly the same as the one in the camaro, except for the heads?

So I could get away with using a caprice engine with the aluminum heads from my old camaro engine?

I ask because the caprice engine is $900 cheaper than its camaro counterpart.

[silicon212]

Originally Posted by stepho

Correct me if I am wrong but the lt1 found in the caprice is exactly the same as the one in the camaro, except for the heads?

So I could get away with using a caprice engine with the aluminum heads from my old camaro engine?

I ask because the caprice engine is $900 cheaper than its camaro counterpart.

To be honest, I'd keep the Caprice iron heads on it - they tend to flow a touch better.

[FormulaLT1]

The aluminum heads don't heat soak like the iron heads do. The end result will be more power with the aluminum heads but yes, the blocks are identical.

[92zcamaroperson]

werent they a lesser displacement though? Like a 5.0 liter or something.

[FormulaLT1]

Originally Posted by 92zcamaroperson

werent they a lesser displacement though? Like a 5.0 liter or something.

Yes, there was a 4.3 version (called a baby LT1) but they also got a 350 version as well. I assume we were talking about the 5.7 version but I should have clarified .

[stepho]

yeah I was talking about the 5.7

[ZL1power69]

the regular caprice got the 4.3 or the 5.0 but the 9C1 and the SS got the LT1.

[ikeyballz]

so theres absoloutely no difference other than the heads? whats with the llower rpm limit on caprice?

[FormulaLT1]

Originally Posted by ikeyballz

so theres absoloutely no difference other than the heads? whats with the llower rpm limit on caprice?

Caprices have different exhaust manifolds, accersory brackets, water pumps , the heads that were already mentioned and harmonic balancers and crank pulley.

[silicon212]

Originally Posted by ZL1power69

the regular caprice got the 4.3 or the 5.0 but the 9C1 and the SS got the LT1.

Wrong for 94-96 - the only engines available were the 4.3 L99 and 5.7 LT1. The 4.3 L99 replaced the 5.0 engine in the Caprice beginning in 94. Civilian cars had the LT1 as a direct option in 1994-96. In 93, one could order the civilian Classic LTZ with either the 5.0 L03 or the 5.7 L05.

[Blue Bowtie]

In addition to the above mentioned differences, the B-Body LT1s also had a lower lift, shorter duration cam profile.



They also had a slightly more restrictive intake duct system. PCM programming for the automatic shifting was softer, and the OptiSpark caps in all B-Body LT1s were ventilated in all years, not just '95 and later. PCM fuel cutoff for some B-cars was set a 255 MPH (effectively no cutoff) so the cars would be drag-limited for top speed. The RPM limit on the OBD-I programs I've looked at is above 10,000 RPM =- Again, effectively no cutoff. The real "RPM limiter" was the use of the standard 85# valve springs instead of something more suitable for a good roller cam, and other intake and exhaust restrictions. (Mine turns 6,500 RPM for short bursts regularly - often enough so that I frequently cross the 1,000' traps in second gear at about 92MPH.) I haven't looked that closely at the OBD-II programming for the B-Body LT1s, so that may have changed after 1995.

However, the "heat soak" theory is all but invalid with the reverse flow cooling system, and the better flowing iron heads had greater potential for power in all ranges. The cars needed the extra power potential to help offset the ridiculously low K-Factor (stall RPM) of the stock torque converters, 3.08 axles, and more restrictive exhaust.

I run my '94 BBBarge at 10.8:1 static (52cc chambers) with 2.02/1.60 valves (something that can't easily be done with aluminum heads), .510/.540 lobe lifts, and can get by on 87 octane if necessary. Head "heat soak" is not a problem. It it is, someone forgot to tell that to my car. Yes, it only run mid- to high 13's, but I can keep a Honda Civic in the trunk as a spare.

[FormulaLT1]

Huh, I never thought about the heat soak effect with the reverse cooling in mind and flow wise in stock form the B-body heads are the superior design but the aluminum heads clean up nicer IMO and I would like to see a dyno comparing the two run by run.

I think the aluminum heads are the better of the two heads once you start getting into modification work, why can't you easily get 2.02 intake and 1.6 exhaust valves?. I know plenty of Vette's and F-body owners running that size valve.

I also believe chamber wise you get less compression in stock form with the Iron LT1 version. Although this can be changed like you did.

[Blue Bowtie]

The aluminum heads have pressed valve seats that sometimes present two problems to machining.

The first problem is the small size and position of the seats. If the seats are not installed in nearly perfect concentricity with the valve port, machining them larger can either break through the seat insert or render it so thin that it becomes a weak point. The head can drop the seat under heat and stress conditions, and that gets very ugly very fast. The seats are made barely large enough to accomodate 2.00/1.55" valves, and while incresing the exhaust valve face size another 0.050" is usually considered minor machining, it can be enough to break through on the small factory inserts.

The second problem is seat retention. They are machined for interference and pressed in place. While in operation, the seats normally only see linear forces from the valve landing on it. While in machining, the seats will be subjected to rotational forces. This may be enough to break the seats free and allow them to spin. Once that occurs, the risk of dropping a valve seat insert is very high. If the head is used (not brand new), the thermal cycling it has had during its service life will make the seat even more subject to spinning out, since the expansion rates of the aluminum substrate and steel inserts are different.

Many machinists who are aware of this will recommend cutting or pulling the factory seats and installing replacements, then machining for larger valves. This can present its own problems, since core shift in the casting process can make a larger seat almost impossible without breaking through the castings into the cooling jackets.

Therefore, while it can be done successfully in many cases, there are risks involved, and in some cases a "simple" valve enlargment can render a casting completely useless. If you ask your machinist about it, don't be surprised if he/she will accept the job but only at YOUR risk, and will not accept responsibility for any damage. If your machinist is not aware of the risks, be wary.

Iron heads merely have induction hardened areas around both the valve seats, and therefore can be machined for 2.02/1.60" valves or even 2.05"/1.55" valves (so long as the exhaust valve is kept smaller to accomodate both of them in the chamber). However, given the flow characteristics of these heads, increasing the intake valve without the exhaust valve is almost useless. The restriction is not really on the intake sides.

As for the aluminum castings being the "better" heads for modification, that's all relative. I know that many of them have had good work done, and have seen improvements as a result. However, I suspect it is easier to start with an iron head and end up with larger port runners and smoother transitions than with an aluminum head. The valve seat inserts alone make blending the short side radii of the valve bowls a very tricky, risky endeavor, and the result would still be a necessarily larger "hump" of material around the short side to keep the seat insert embedded in aluminum. The iron just doesn't care. I also suspect that removing enough material to yeild 194/80cc finished runner volumes would be dangerously close to hitting water on an aluminum casting. Very easy in iron: