i have a 99 Z/71 with a 5.3L with K&N FIPK, and dual exhaust. the engine has 203,000 miles on it and i want to replace the engine. i have been looking at a 402 cu. in. short block from SLP but i have a couple of questions about the swap.

1) the new short block from SLP is an LS2. will it fit in the truck and are the motor mounts the same as the original gen. 3. and will aftermarket LS1 heads fit on the LS2 block.

2) is this short block assembly strong enough to be blown? i am also considering a procharger or vortech centrifugal supercharger.

3) and last but not least, will i be able to use the stock computer from the truck and just get it reprogrammed of will i have to get a new computer.

A) if i do get a new computer which way is the better way to go?
a FAST computer system or reprogrammed LS2 unit, or
aftermarket PCM. i dont know much about this computer tuning
stuff so i need all of the help i can get in this area.

thanks ahead of time for all of your help.

 

I'd work with SDPC, personally, or pick up a used LQ4 and do the machine work locally.

You'll need a computer that matches your sensors and harness -- the rest is all programming. There are plenty of options in the aftermarket sense, from BigStuffIII to megasquirt, but all are pretty computer intense. Probably your best bet is a stock computer and a custom dyno tuner.

40x ci strokers are awesome on boost. You just need to make sure you get a big enough compressor to feed it.

 

anyone ever built a 427?

 

Out of a C5R, yes. Out of a 6.0L, I'd heard of a 422, but never actually saw anything substantial. 1SlowZ71 built a 418 out of a 6.0L -- he had some trouble with it during the build (as everyone who does something "first" does), but it runs strong from his reports.

 

A 418 is PITA to get all the clearances right but it does make my Z get up and run good. I am having some oil pressure issues that arent related to the CI that I went with. Im running the stock computer system with a custom tune. It will out run bolt on SS camaros with a pig rich tune so I would say it runs alright for a 5400# truck.

 

The bottom line with the issues is that the extra .100" stroke (over the 408) pulls the piston .050 more out of the bottom of the cyl. allowing it to rock more when transfering back up. This extra rocking was causing the piston skirts to hit the counterweights. He had to have material removed from the skirts twice which consisted of back-cutting the skirts a little and shortening them by about .080". The extra rocking, over time, will promote more gauging of the piston skirt into the bottom edge of the cyl wall. This is common of course with stroker engines. I would not go any longer than 4.000" stroke for longevity & reliabilty reasons. The c5r has a 4.125" bore and 4.000" stroke.

 

Do a search on the SLP ZL402. I posted about 6wks ago asking for feedback and didn't hear too many good things. I do know somebody thats installed 2 of them and they are oil burners he says. Also, I was told they have crap pistons (Ross) and too short a skirt/bad rings. For some postive feedback talk to H3 Automotive in NJ or on the web. They work with SLP and have very good knowledge of the motor. SLP was definately one of the cheapest installs and a good name, but I heard too many nitemare stories that included crap customer service - and I ABSOLUTELY will not tolerate poor aftre sales service. My 2 cents. R/