i just bought a black '98 c5 coupe. it has 82k miles on it already. first i would like to know when the ls1 starts to give out and what mods i can add to give me more power without sacrificing driveability. i already have a borla stinger exhaust(came on the car). i don't want an insane amount of power but i would like to be putting down around 400-450hp to to the wheels. thanks in advance for any info.

 

probably the easiest thing to do to get that horsepower that you are looking for is to get new heads/cam and a built bottom end. just get the block machined and bore it +.030 to clean up the cylinders and put new pistons, pushrods, bigger injectors, maybe a new crank... you would probably be pushing 400-450rwhp or maybe even more if they tune it right. it might cost quite a bit, but the heads are the powerhouse of your engine and replacing those with better ones (or maybe even just getting yours port/polished) will definately add some good power.

 

The LS1 stock bottom end starts to have problems at around 485 RWHP. Up to that point is is fairly strong and durable, assuming you don't abuse it in a bone-headed manner. I've known a number of people, including myself, who have gone tens of thousands of miles at around 450+ with no problem on a stock LS1 or LS6 engine. I know one person who was getting about 450 RWHP from an engine modified when it had over 125,000 miles, and it raced every weekend - the motor lasted to nearly 166,000 miles and over 300 hard 1/4 mile passes (I think this was an extraordinary case, though).

The rear end tends to give up if you abuse the car when you have this much power - it will take just about anything except a very hard launch with slicks-if you plan to do this you need to buy a "girdle" to reinforce the case or an extra-duty rear end.
There are heads and cam packages.

All that said, given that your engine have 82,000 K on the short-block, if you have the money I'd replace the whole bottom end with a stroker kit, or just buy a whole 402 short block from someone (numerous folks supply them at around $3000-$4,000). Reasons are, with 82,000 miles of you-don't-know-what-type on it, it might be a bit tired - you just don't know, so replacing it would not be a bad idea given that you are going to mod the car and really need it to be in good shape, AND, nothing produces power and good old low end torque like more displacement.

 

A 402 sounds like it would fit well in the C5's. But let me ask you a question Lee; Why doesnt anyone have a 383 application in their C5's? I never hear about the 383's except for in C4's. I drive a C4 so hearing about the 383 is a common occurance, from people telling me that they have one, to people telling me that they are the best things in the world and i need to get one. That is all i hear about. But, i never hear about them for C5's. Maybe you can enlighten me a little.

 

There are lots of 383 LS1s and LS6s out there. I know of four or five running around Raleigh, NC, where I live.

But the reason you hear about 402s instead of 383s is this: a 402 short-block costs no more than a 383 short block. You can order either but the difference in price from most suppliers is neglible. They use a slightly different block (LS2 I think instead of LS1) and its different bore gives the added cubes with the same stroker crank.

Alternatively, if you really plan to abuse the bottom end with 700+ HP, you can go for an iron instead of aluminum block (that used in Chevy Avalanche 5.7 liter is identical to the LS6 aluminum block, but iron. It weights more but can take more power, and you can bore it (you can't bore the alum. blocks) so that with the same stroker crank you get 408 cubes. That's the engine in my Camaro.

 

thanks for the info guys...lee you said you live in NC; I live in Gaffney SC and was wondering if there are any reputable garages around the nc-sc area that i can take my car to when i do get some add-ons or order parts through. I can do basic bolt-ons but the more advanced stuff i leave to a trained mechanic.

 

More Performance (it may be spelled Moore Performance, not sure) is in charlotte, just off 85 about 2-3 miles past the airport. They do really good work, I hear.