I was getting ready to build a twin turbo LT1 for my 96 Impala using the 396cid LT1 stroker I had in the car, but after tackling a year long project on my 70 challenger where I had to build just about everything from scratch (including an entire procharger setup) I am really tired of custom parts, fabrication work and engines that you have to drive with one eye on your gauges.

I'm looking for a crate motor that will bolt up as easily as possible using all the existing LS swap parts, factory reliability/efficiency and could hit 700RWHP through an auto when the boost is cranked up. I'm looking to use a roots blower this time around because I really don't want the hassle of welding up turbo piping and trying to squeeze them in a cramped engine bay.

I REALLY wanted to go with the LT4, but it looks like I'd have to wait a few years before a swap like that becomes bolt-on-able and I'm not looking to blaze any new paths here. I want this to be quick, easy, as cheap as possible and something the makes me feel like I'm driving a production car.


I've always loved the idea of the LSX 376 B15. endless power potential, the cam is pretty mild for a daily driver and it shouldn't take much more than a Whipple and a tune to lay down big numbers. I'm on a budget, so if I did the b15 I'd likely have to throw it in N/A for now or maybe use a pre-owned LSA blower and go for the whipple later.


however, I also found a good deal on LSA crate motors selling for a couple thousand cheaper than the complete GM crate engine (they were ordered from GM by a custom car shop sans exhaust manifolds and the GM warranty has expired.). It would allow me to have an LSA with blower for just a little more money than the B15 long block.

I love the idea of just bolting in a complete, turn key GM production motor driving the snot out of it like I would any new car. I'd be happy with the HP #'s that the factory blower could produce for now, but I'm just worried that when I'm looking to expand my horizons that the cast pistons and powdered rods in the LSA are going to be a huge limiting factor.


What are generally considered the safe limits of the stock LSA long block?

 

And yes, I am on a pretty tight budget and after many hours of research and a lot of note paper I pretty much narrowed down the cost of the swap with accessory brackets, wiring, mounts, headers etc... I've already have a 450LPH automotive Phantom fuel system in the car, a Cahall Performance pro race 4l60e (LT1) with billet output shaft, I built the 8.8 up with Moser axles, 1350 yoke, Eaton Posi etc... I notched and boxed the frame with 335/35/17 DR's out back so the car is ready for something fun.

Now I just want that something to be as easy, quick, painless and cheap as possible while giving me a solid platform to keep up with the new cars in both reliability/efficiency and power.
by https://www.flickr.com/photos/145918422@N04/, on Flickr by https://www.flickr.com/photos/145918422@N04/, on Flickr

 

The b15 has the same rods as the lsa.

 

The only 2 things the lsa has is weight and squirters as an advantage.

Everything else goes to the 6 bolt LSX based b15

 

Definitely more hp potential with the whipple

 

Didn't realize that, a a few sites were just listing them as "forged rods" but I just found the part number and cross referenced it and you're right. They are forged powdered metal...but I would imagine they'd be much stronger than the old design powdered metal rods in the truck motors and guys ran those up to 850+HP. IF the LSA rods are good up to 1000 crank HP then that should be all I'll ever need.

The LSX B15 may be overkill for what I'm intending to do (I don't think I'd ever be looking to make over 1000 crank hp) but I don't know if the LSA has room to grow if I wanted to get there without having to do a cam swap and possibly pistons. I know the LSA motors have the oil squirters, but I'd imagine the cast pistons can still only take so much...and I don't want a time bomb or else I'd be doing a junkyard 6.0.

I'm just thinking now about whether there are any disadvantages in drivability/efficiency when at low boost numbers with the B15. Since the engines are pretty similar in design I wouldn't think so, aside from the slightly more aggressive cam in the B15.

I'm not too concerned with weight as the Impala came with an iron block/iron headed LT1...so the aluminum headed b15 with blower hopefully won't be too much of a difference as opposed to swapping it into an F body or something that had an all aluminum motor.