L99 engine

i have resently aquired a 94 caprise w/ a 4.3L V8, i was wondering if there is any information out there about this engine, i have searched only to come up with it being a L99, similar to the LT1, how true is this...
i was hoping to be able to use the fuel injection system off this L99 and swap it onto my L81, but was unsure about the type of injection it uses...
one last thing, anyone know what type of heads are on the L99?

thnx for your time,

SpartanSith

The basic low down on the L99:

It is basically a de-bored and de-stroked LT1 with supposidely the same horsepower per cubic inch (265-cid to 350-cid) as the LT1. Both the L99 and LT1 feature sequencial-port fuel injection (fires each injector fires when the corresponding intake valve opens). The L99 features the same bore and stroke as the original small-block (265-cid).

thnx for the info, helped alot, any idea on the heads though, my 1981 L81 heads are kinda restrictive i think, so they should be better anyway, right?

SpartanSith

You cannot use the L99 heads on anything other than an L99 as the water ports are completely different. The L99, like its big brother the LT1, is a Gen II Small Block with reverse-flow cooling (the water jackets are redesigned to allow the heads to be cooled first instead of last) and even though they externally look similar, they are different and not interchangeable. Same goes for LT1 heads.

so all that would have to be done to this engine to make it a LT1 is bore and stroke it, right? what about injectors or anythin else?

thnx,
SpartanSith

I imagine the LT1 has higher flowing injectors than the L99 because I've been told that is what Chevrolet did with L05 and L03 (L05, having larger displacement and being seen as the high performance engine, had slightly higher flowing injectors).

I have this all detailed in a thread on another forum, but I did the swap from an L99 to an LT1. You can not bore an L99 enough to get the LT1 bore not even close and yes the injectors are different. The intake and exhaust manifolds are the same as are the cats behind the cats the L99 goes single exhaust the LT1 dual easy to add the hangers and run any readily available catback.
The pcm is the same part number just needs to be reflashed there are a handful of guys who can do a custom LT1 tune for you for under $100.
Once that other forum is back up and running I will try to post a link to all the details of my swap. It really is pretty boltin, no sensors need changing all accessories are either exactly the same or will work perfectly. I got my LT1 out of a 95 Roadmaster with lots of extra parts it was $550.

What I meant was an LT1 was "basically" bored and stroked L99, just like the L05 was "basically" a bored L03 (although I don't think you can overbore it enough to make an L05 out of an L03).

What I meant was an LT1 was "basically" bored and stroked L99, just like the L05 was "basically" a bored L03 (although I don't think you can overbore it enough to make an L05 out of an L03).


I understood you, was more replying to spartansith's last post.

The 305/350 comparison you make is a very good one.