LS1, ZZ4, or custom build.

I like the LS1 for the power and aftermarket, but am looking to preferably go new, and don't wanna pony up for the transmission to go with it. I like the idea of the zz4, but wonder if a build would be cheaper.

It's my 91 RS. I'm looking for around 375hp at the wheels, 425 ish ft lbs at the wheels. Hoping to keep stock transmission (74k, and strong, no mods). At the moment have the stock rear end, stock gears. After the motor is done I intend to at a minimum swap gears to 3.42, but I'm debating an entire rear end swap. It'll take a lotta research that I haven't done yet, because size/length lug nut on the left to lug nut on the right needs to be 100% the same - I squeezed 10 inch wide rear rims with no room to spare (i can squeeze a finger between the wheel/rim and fender wall).

Don't care if it's injected or not..i'd almost say not to save the wiring and programming headache. Reading this back now..I'm more ZZ4 than LS1.

What do I do - what would you do? HP range I mentioned, trying to avoid a trans swap (will my stocker take those numbers without breaking), planned rear end swap in a year or 2. If you say "build" - tell me what you suggest. Looking to keep it ~$5200, preferably cheaper. More than likely want a new block - I'm not a fan of buying someone else's problems, and I wanna keep it clean to show. I'm leaning towards zz4, considering ls1, open to suggestions.

 

I'm afraid a dose of reality is in order.

The ZZ4 puts out 355 gross flywheel HP. No way no how are you getting it to 375 RWHP. It costs almost $4900 before tax and shipping, so you're already over budget and underperforming.

If you get the shortblock with Fast Burn heads and RPM intake, now you're up to 385 GFWHP. Still way short of your goal, and over $5200 before tax & shipping.

The first thing you need to be willing to give up is your transmission. It may be fine behind a 170 NFWHP LO3, but it won't hold up to 355 GFWHP without some help. Converter and shift improver kit at a minimum.

The LS platform is capable of meeting your performance goals, and they are pretty tough engines. A freshening up may make you feel better, but probably isn't necessary. Exhaust and a few other smart upgrades will get you to the power goal. Haven't had mine on a dyno, but based on 1/4 mile performance, it's at least close if not over the 375 RWHP level.

 

Think I should get the tranny built or it needs to go regardless of the engine? Which is more cost effective? From the sound of it you're recommending ls1? I wouldn't mind maybe getting one low mileage one outta a crashed car, but sub 40k ls1/4l combos are what a new engine would run me.

 

Jen-Cen is right in your backyard.Talk to Mike.He's a straight shooter.He might have some leads for you.

 

Dollar-per-dollar you'll get more out of the LSx, but you'll spend a lot more getting there. Prices have come down over the years, but they're still somewhat expensive in comparison. My SBC is making over 375 to the wheels and it cost me much less than a LSx swap. I priced things out separately for each one before deciding what I wanted to do. SBC will also be easier to put in; particularly if you don't want to deal with a ton of wiring.

Don't buy a motor from Jegs/Summit/whatever. It's a ripoff. Go to a local, reputable machine shop and get them to build you a shortblock with your parts that you pick out instead.

 

Gary have you worked with them? Do they do good work? If I build I'd like to do it w/someone and actually learn something - think they'd be open to that?

 

Jim Mike's father started that company back in the 1960's.Mike campaigns a Pro-Mod car that is very competitive.Yeah they know what they are doing and been doing it for yrs.