1961ba427

iTrader: (26)

Okay....let me say up front that I already know this will not be very powerful and that I could part out the Z28 and buy a clean running V6 and be money ahead. That being said I have my reasons for considerring this.

I bought this car as a parts car with a knocking LT1 and got a great deal on it, but it's too nice to part out. My fiance has now claimed it. She doesn't really care if it's quick as long as it sounds like my SS.

So hear are my reasons for the L99 thinking:

1. This will probably be one of my kid's first cars in 4 or 5 years. Don't want them starting out with 300+ rwhp yet it would still look like one.
2. L99's are dirt cheap when you can find one.
3. Everything LT1 will interchange I'm thinking. Start them off with the 4.3, bolt-ons, long tubes, etc......build the pulled LT1 with them....letting the kid work to buy the parts and get greasy...actually learn something. Then it's an easy swap to put 350+ inches right back where it came from.
4. GAS MILEGE I'm thinking this little baby with a T56 and a 4.10 gear behind it should be almost as quick as a bone stock Z28, but get maybe another 3 to 5 MPG?? We are talking 85 less cubic inches to feed and 19 vs 24# injectors.

I'm thinking maybe something along the lines of the stock LT1 cam or maybe the XFI466 to keep the thing from getting too peaky. Also about using the aluminum LT1 heads. Wouldn't these fit as long as I stick with the stock 1.94"/1.50" valves? I know the bore is the same as a 305, and you can run those valves with no problem on them.

So that is my brain storm for tonight. Let the trash talking and people telling me I am crazy commence.

tricked94camaro

iTrader: (1)

doooo itttttt

NewOrleansLT1

I seen a 95 Cadillac Northstar V8 swapped into a Camaro before, so this doesn't surprise me.

1961ba427

iTrader: (26)

What I'm talking about shouldn't even be considered an engine swap really....the 4.3 I am talking about is in the LTX engine family. In fact it is the only other engine besides the LT1 in the family. (unless you consider the LT4 version another engine) I would be using the LT1 Wiring Harness, T56, Intake, Heads (hopefully), etc. Really the short block is all I'm talking about being NOT an LT1. This would be a complete bolt-in.

I did forget to mention in the original post, that I know I would need a re-tune, but that is needed with most any mods.

Anyone have input on using the Aluminum LT1 heads from the 95 Z28 on the L99? Are the L99 4.3L Cast Iron heads the same as the Iron heads used on LT1's in the B-body Impala/Caprice/Roadmaster/Fleetwood?

What are the chamber and valve sizes on the L99?

I also realize I could use just the crank and rods from one in the LT1 and build a 302" engine using the stock LT1 pistons and may end up trying that instead, but I think the 265" would be better to reach my goals of not too much power and great mileage for the fiance and/or one of my kids.

01ssreda4

iTrader: (96)

Great idea however, the 4.3 with bolt ons wont be "almost as fast as a stock Z". At least I dont think so.

tricked94camaro

iTrader: (1)

how did they manage that? isnt the northstar FWD?

RamAir95TA

iTrader: (2)

I don't think the bore size of the L99 will allow for the larger valves of the LT1 heads.

96capricemgr

iTrader: (1)

Keep the L99 heads and it already has a stock b-body LT1 cam so keep the stock cam too, maybe give it some valvesprings and 1.6s but that is all I would do under the valvecovers of that motor. I say this as someone who owned one, my car came with a L99.

I don't think you will see a lot of fuel economy gain, maybe a couple but not 4-5.

I think this could be a neat way to keep the car cheap and reliable.

Just remember to reprogram the pcm.

WS Sick

I think this is the most important to keep it from running like a pig.

idformula

The LT1 heads should fit, those size valves are used on 305's all the time just make sure you check the valve to cylinder clearance to make sure the cylinder doesn't need notching, the LT1 cam would be alright for it give it a little more hp than the stock cam, or a roller version of the Comp 260 cam. but the most important thing would be propper tuning for this small of a motor IMO.
Just my .02

1961ba427

iTrader: (26)

For tuning, wouldn't it be as simple as tuning any bolt-on car, only I'd be starting with a stock L99 B-body tune instead of the LT1 one?

WS Sick

Use a stock LT1 tune and adjust the displacement. If you have a b-body tune copy the timing over, the b-body tune will have a smaller maf.

1961ba427

iTrader: (26)

Thanks for the info....I have very little tuning knowledge...I just know some basics and would be relying on a friend for this. Wouldn't we need to adjust the F-body tune for the smaller injectors also? Would the 24# LT1 injectors be a useful upgrade to the L99 if it had full bolt ons? (Tuned accordingly)

WS Sick

Yeah just use the LT1 injectors, not sure of the size of the L99 injectors.

96capricemgr

iTrader: (1)

A magazine did an L99 buildup years ago with the LT4 crap including notching the bores and all and got a whopping like 300hp. Don't waste the time and effort to put LT1 heads on it. You would accomplish little beyond destroying compression and lowend.

The L99 injectors are 19lbs, LT1 injectors wont be an "upgrade" just much larger than necessary, tunable but WAY beyond what would be needed.

Here is a side by side pic of an L99 head and an iron LT1 head.
I no longer have the L99 heads so I can't get any more pics or measurements.
http://s120.photobucket.com/albums/o...t=DCP_0315.jpg

1961ba427

iTrader: (26)

I'm thinking the L99's are on top/ iron LT1's below?
Doesn't the iron LT1 have a bigger chamber than the aluminum LT1, but also used a thinner head gasket to make up some (or all) of the compression difference? (Not trying to be a smart ***....real question there.)
I can see how the LT4 stuff wouldn't work well clearing due to 2" valves, but think the 1.94's would clear since they clear on a 305 which has the same bore as the L99...so was thinking of using them along with a thin head gasket and/or milling to maximize compression. I wouldn't be considering this if I didn't already have a couple sets of aluminum LT1 heads to use. I can also see how the LT4 port sizes would be overkill for such a tiny engine, but was thinking maybe stock LT1 heads would be a decent upgrade.
I appreciate the experience and replies. If the 24# injectors are WAY more than necessary (was also considering due to already having them) then would a set of 22# as used on L98 TPI engines be better than the stock L99's? (also have some of those already.) Guess what I am asking is how much will the L99 injectors feed without being nearly maxed out.

WS Sick

I beleive the L99 heads are 58 cc chambers, just like the alum. LT1 heads.

1961ba427

iTrader: (26)

If that's the case I wouldn't lose compression.
Also I figured out I was wrong about the pic. The LT1 heads are on top/L99 on bottom.
Also, I already knew about using L99 crank/rods with LT1 block/pistons to build a 302, but didn't realize you can do L99 block/pistons with LT1 crank/rods to build a 305. I wouldn't bother with the 302 since it would be more peaky comparatively, but the 305 could be built for cheap and should still get a couple more mpg than the 350 LT1. It would also close the cubic inch (and therefore HP/TQ gap) by alot.
Still think with my intent for such a project that sticking with the stock bore/stroke L99 would be best. Looks like I could use some Higher compression off the shelf 305 pistons for some easy power though. CR usually helps with efficiency in the gas mileage area too.

GIZMO

iTrader: (8)

The L99 is a great little motor. You do not need aluminum heads or bigger valves to go fast with one. The stock heads work just fine. If it were me I would put good lifters and valvesprings in it and call it a day.

My little L99 went mid 7's in the 1/8th at 3300 lbs in my Camaro with just a cam, stock replacement .030 pistons (from GM), and valve springs!

A larger than needed injector is never an improvement.

1961ba427

iTrader: (26)

So there is nothing at all to be gained with better heads? That just doesn't sound right....or are you saying that the aluminum head is not any better? (Doesn't sound right either) OR more likely, you are just saying the aluminum ones would be better, but not necessary. ?? Again, I'm primarily asking because I already have them. I'm sure if I find an L99 it would have it's head still too.
I'm kinda glad to hear that the stock 19# injectors are more than capable.

Lastly, I mean no offense (this is actually a compliment really) but saying a L99 went mid 7's in YOUR camaro with just a .030" bore, cam, and springs sounds very impressive UNTIL I remember that your car is completely sorted out and set up bumper to bumper. I mean what do you think your car would run with a bone stock/never even rebuilt/stock cammed LT1? I'm sure it would still be quicker than most people's bolt-on or cam only street/strip cars.
Honestly what do you think the same L99 would have ran in the typical street car with normal weight, A/C, bolt-ons, gears, and drag radials? I am asking seriously because I have zero experience with this engine.

Anyway, like I said originally, I would be happy with performance typical of a STOCK (as in no bolt-ons) Z28 which would be very high 8's to mid 9's in the 1/8th and a decent improvement in gas mileage. Just something mild and fun for my fiance or my kids to learn and grow with.

Someone above mentioned that I'd probably only see a couple more MPG instead of the 4-5 I thought it would at least get. What do ya'll think about that? Maybe I should ask some B-Body guys about that instead of on here??