Hi,
Are the rods, pistons, and crank on a '73 LS-4 cast or forged?
I'm thinking about supercharging, and I just wanted to figure out how far I could go.

Thanks,
K McKiou

 

OK. Since I have had no replies, let me rephrase. Does anyone have a pointer to the stock crank, rod and piston contruction for the LS4? I've searched and, so far, have not been able to determine if they are cast or forged.

Thanks!

 

If I were you I would take apart the engine to verify the condition of the internal working parts before putting on a supercharger (blower?) or a turbo and also to verify everything that's forged or cast. Both systems put a tremendous amount of strain on the engine and may require specific compression ratios for the best performance. Rather be safe than to be picking up broken parts along the highway.

Just IMO, but still didn't answer your question.

Good Luck

 

The crank is cast (there have been rumors of some 454s with forged cranks), rods are forged, pistons are cast aluminum. There are Chinese forged steel cranks on the market for under $1000 (I don't think much of them), the rods are OK with good ARP bolts untill 7000RPM (solid lifter cam country above that) I would consider the useage and decide whether to run forged or hyperutectic pistons. My buddy built a 72 LS5 454 that runs 120+MPH in the 1/4 mile using the oval port iron heads (ported with 2.19/1.88 valves), stock crank, rods (with ARP bolts) and KB hyperutectic pistons (no NOS! without forged pistons) and a Com Cams hydraulic roller cam. The money was spent in the right areas and the guy had a FAST Vette for under $4500.

 

Solid,

Do you happen to know which cam your friend was running? Sounds like he had a nice combo.

 

I will have to check and see what was installed. Give me a few days to get back to you on the cam specs. The car was a 4speed with 3.55 gears and I remeber it running 12.60's at Vette Magic #26.

 

I don't know about all of them but mine has a forged crank. (4spd. )

 

Here is some information that I picked up someplace?? Either here or the NCRS forum.

"Well, I can't give you a particular source that will offer comparative or sole-source spec information. However, I can provide some info if you understand that virtually all of this is coming from memory and may not be 100 % accurate. But, with that caveat, here goes:
1) All 70-74 Corvette 454 cid engines were two bolt main configuration EXCEPT 1971 LS-6;
2) Most, if not all, 70-72 Corvette 454 cid engines used a forged steel crankshaft. There may have been some exceptions, though, with those using a cast nodular iron crankshaft;
3) All 73-74 Corvette 454 cid engines used a cast nodular iron crankshaft;
4) All 70-74 Corvettes with 454 cid engines, except 71 LS-6, used the same size intake and exhaust valves which, as I recall, were 2.06" intake and 1.72" exhaust.
5) 1970 LS-5 cylinder heads were unique to that year. For 1971-72 LS-5 engines, although different castings were used for each year, the cylinder heads were, essentially, the same. 1973 and 1974 LS-4 engines used cylinder heads specific to each year which were different for each year. As I recall, all 1970-72 LS-5 engines used cylinder heads which had about the same intake and exhaust port volumes. 73-74 LS-4 cylinder heads had smaller intake and exhaust ports, although I believe that 73 and 74 were about the same. All cylinder heads, except 71 LS-6, were cast iron material. 70-72 cylinder heads did not use induction hardened exhaust valve seats, including the valve seat inserts used on 71 LS-6 aluminum heads. 73-74 LS-4 cylinder heads used induction hardened exhaust valve seats;
6) All 70-72 LS-5 engines used the same camshaft, GM #3883986, which was also used on 66-69 L-36 427 engines. 1973 and 1974 LS-4 engines used a different camshaft, GM #353040, which was the same for both years. This camshaft was an "emissions profile" camshaft;
7) All 70-74 454 LS-4 and LS-5 engines used the same connecting rods which were forged steel with 3/8", knurled shank rod bolts;
All 70-74 LS-4 and LS-5 engines used cast aluminum pistons. The piston dome configuration was unique to each specific year, however, even though compression ratios may have been the same (72-74). 1970 LS-5 used 10.25:1 compression ratio; 1971 LS-5 used 8.5:1 compression ratio; 1972 LS-5 used 8.25:1 compression ratio; 1973-74 LS-4 used 8.25:1 compression ratio.
9) All 1970-74 Corvettes with 454 cid engine used the same oil pan, including LS-6;
10) 70-72 LS-5 engines used unique-to-each-year cast iron intake manifolds. However, all of the manifolds were similar. 73-74 LS-4 intake manifolds were also cast iron but had smaller port size to match the 73-74 cylinder heads. 73-74 manifolds also incorporated provisions for EGR.
11) All 70-74 Corvettes with 454 cid engines used the same side-specific exhaust manifold castings. 1971 with LS-6 and all 73-74 LS-4 manifolds were drilled and tapped for A.I.R. fittings.
12) All 70-74 Corvettes with 454 used the same valve springs except the 73-74 exhaust valve springs which were shorter to accomodate the rotators used during those years.
13) All 70-74 Corvettes with LS-5/LS-4 engines and manual transmissions used a 14" cast nodular iron flywheel with an 11" clutch. LS-6 used a 14" flywheel with a special dual disc clutch;
14) All 70-74 Corvettes with LS-5/LS-4 used the same oil pump
15) 1970-72 with LS-5 used the CCS (controlled combustion system) exhaust emissions control system. All 1971 LS-6 and all 73-74 LS-4 used the AIR (air injection reactor system) exhaust emissions control system.
Many of the horsepower/performance differences, particularly during the 72-74 period, were the result of emissions control system differences."

Hope it helps.
Terry

 

Holy cow, Terry! You are a regular fountain of knowledge. Thanks very much for the detail. This brings up a neat thread - modifying a 454. I was thinking about forced induction, but realize there is probably a lot that can be done without a great deal of expense - but that is another thread.

Thanks again,

- Kevin

 

No rumor about it!! My stock 70' 454/390hp has a forged crank with Brent Brooking
Bullshark