Difference in Engines between Caprice Wagon LT1 and Corvette Engine

[Rs2sensen]

I was recently involved in a crash with my 1994 Caprice Wagon, and wanted to inquire as to the difference between the LT1 that went in the Caprices vs the Corvettes of the time, so that I can properly list the car and engine for sale. If anyone also knows what the Caprice engines are going for right now on the parts market, that would also be appreciated.

Thank you,
Ryan Sensenbrenner

[j cAT]

Originally Posted by Rs2sensen

I was recently involved in a crash with my 1994 Caprice Wagon, and wanted to inquire as to the difference between the LT1 that went in the Caprices vs the Corvettes of the time, so that I can properly list the car and engine for sale. If anyone also knows what the Caprice engines are going for right now on the parts market, that would also be appreciated.

Thank you,
Ryan Sensenbrenner

I would list this engine as it is a 1994 LT1 ...
the person looking to buy this should know what use would be correct...

It is not the same engine as the corvette..

the most major item is the fact that the corvette has aluminum heads, not cast iron...

[silicon212]

The Caprice LT1 has cast iron heads; the Corvette uses aluminum heads. The cam profile is different between the two applications, that's the largest difference. The cast iron Caprice heads actually flow better than the aluminum Vette heads do.

Do list it as a '94 - there are differences between the years pertaining to sensors, etc. OBDII in '96 and all that stuff.

[Blue Bowtie]

The '94 B- and D-Body LT1 used a ventilated Opti. F- and Y-Cars didn't get that until late in 1995. The iron heads can be fit with 2.02/1.60 or 2.05/1.55 valves. The aluminum heads can take 2.00 max. In addition to better port flows out of the foundry, the iron heads can be ported for more flow than the aluminum without fear of weakness. The only advantages to the aluminum are less mass and a wee bit better cooling, but the reverse flow LT1 cooling system does a more than adequate job in getting that done with the iron heads.

The cam profile of the B- and D-Body LT1 is very tame by comparison to the Y-Cars.

The Y-Car LT1 has a different EGR system.

The rest of the engine assembly is the same, year for year.

[j cAT]

[quote=Blue Bowtie;6105236]

The only advantages to the aluminum are less mass and a wee bit better cooling

quote]
the corvette engine has more H. P. because of the aluminum heads...check out the spec's ...back in 1994 was when I got very interested in this, as the IMPALA got built..

I believe the vette engine is 92 octane where the impala LT1 is 87 octane..

[Blue Bowtie]

Actually, the chambers of the iron heads can be a little tighter, and the big difference is in the stock cam and valves. The stock cam of the B- and D-bodies had anemic 0.418/0.430 lifts and 191/196 durations for 1.94/1.50 valves. The Y-Car got at a minimum 0.450/0.460 lifts and 202/207 duration for the same valves in the LT1 version. Unfortunately, both used the fairly tame 85 pound springs found on almost every built Chevy since Cole designed it.

The later aluminum LT4 heads had better port positions and runner designs, slightly larger valves at 2.00/1.55, and were held up by slightly better 110 pound springs. The ports of the LT4 heads were opened to about 196cc on the intake side but were still only about the same flow at comparable valve lifts to the other iron or aluminum heads. Again, porting the iron allows for a lot more latitude than with the aluminum heads. I was easily able to go to 194/75cc on the iron heads with a conservative port repositioning (up 0.100").

The stock aluminum heads averaged 54-56 cc while the iron heads were about 53-55 cc (54.4 average on mine) as cast. It's a minimal difference, but certainly no advantage for the aluminum heads.

So as you might imagine, the aluminum LT1 heads were not a lot different than the iron versions, only a bit thicker. I'd still bet that most of the difference in stock power ratings is in the cam. The LT4 heads were quite a bit better, but the LT4 cam, stock 1.6 aluminum rockers, and better springs also made a substantial difference. The fact that the aluminum headed engines went in cars weighing at least 1,000 pounds less didn't hurt their mystique.

The "stock" iron heads I now have on my '94 have 2.02/1.60 valves pushed to 0.510/0.520 at 220/230 duration. I tried two different cams on the last setup and the first cam (0.500/0.510) was an improvement, but the second cam (0.510/0.520) was noticeably better. I picked up a little power from the stock rated 260P/300 ft/lb to 382HP/427 ft/lb on the stock bottom end. There probably isn't a stock LT1 or LT4 that can match it.

[96capricemgr]

The aluminums can be made to work exceptionally well too IF you let someone competent do the work. I have 2.00/1.56 valves cam is a fair bit larger, upper 220s and .600ish lift, BUT estimated HP based on performance is more like 500-520fwhp.

Heads are 200cc after porting GM aluminum castings.

11.5 seconds and 115-116mph in the quarter is nothing to sneeze at for a true NA street car, that is full exhaust system exiting at the bumper, AC, ABS, street front tires.

I do plan to put ported iron heads on my wagon, but for maximum performance I choose to take advantage of all the R&D some shops have put into the aluminum heads. Seen a few guys have the iron heads crack too if they are opened up too much in the bowls.

[Blt2Lst]

I was just reading that the corvette LT1 has 4 bolt main caps and the others only have 2 bolt mains.

[96capricemgr]

Meaningless, the actual block casting is the same and the rod bolts will walk before the maincaps. By the time you need 4-bolt mains you need aftermarket main caps anyway. Yes it is a difference but a nearly pointless one.