I'm just curious, being new to the z world - what is the most any of you guys have gotten out of a L28 as far as horsepower, with mods and all? I searched the forums a bit and only came across numbers for stock engines.

There's a good thread on the topic at: http://forums.hybridz.org/showthread.php?t=91068

With the stock engine, I think that 200hp is fairly obtainable, but 250hp is getting near the end and hard to get there. With the turbo L28, I think that 250hp is a little easier to get there, but still near the limits. Maybe if you take the L28 and make it a 3 to 3.2L with a turbo you might be able to get 300hp but will still be a pretty penny.

This is just what I have picked up from all the research that I have been doing myself on modifying my L24 or just swapping engines. I have decided to just do some basics and get as close as I can to 200hp, though I would need a triple carb set to really make sure that I get 200hp. Though that will cost $1500 just for 50hp, and I had rather get an engine with that sorta money doubling my horsepower.

With the turbo L28, I think that 250hp is a little easier to get there, but still near the limits. Maybe if you take the L28 and make it a 3 to 3.2L with a turbo you might be able to get 300hp but will still be a pretty penny.

http://forums.hybridz.org/showthread.php?t=115904 Many people have gotten 300whp out of a bone stock longblock. The stroker adds displacement so it will add in a fairly proportional manner more hp based on the increase in displacement. So a 2.8 that makes 300 whp will make ~330 whp built the same way, but as a 3.1. There are dyno sheets over at hybridz.org for guys pushing over 500 whp out of L series engines. Takes a lot of money though, and if you're really looking for that kind of power I'd suggest a V8 swap.

With the NA engine running on street gas it seems the limit is about 85hp/liter or so, but the effort and $$$ involved in building that engine is a lot more than would be needed for a comparably powerful V8 swap.

My L-28 makes 372 horsepower and 365 Ft. Lbs. of torque at the wheels on a 248 dynojet, the long block is nothing fancy, J+E pistons and a small schnieder cam, but a pretty good sized turbo, full T-04S, 60-1 compressor and a .58 P-trim hotside, I'm currently building another motor with loads more tricks to it, maybe 450 to the ground... I'll soon find out.

It's not what I would term "cheap' to make this kind of power with an L, I have loads of money in all the "bolt-on" stuff, Spearco intercooler, 550cc injectors, wastegate, fuel system, Haltech stand alone EFI, it all adds up in a big hurry, even if you use a junkyard motor, the other components required to make big power numbers cost.

IMO, the money is worth it, nothing feels quite like a high powered L turbo spooling up and mashing you back in your seat.

jmortensen mentioned hybridz.org, take a peek over there, the most powerful L motor's on the 'net for sure, more than one of them making 450+ wheel horsepower, street driven.