Turning L99 into LS3

[SamSS]

How hard would it be to turn an L99 into an LS3? I mean the difference between the two is the bigger camshaft on the LS3, compression ratio, and AFM. So if I just get the LS3 camshaft and tune it, it'll be an LS3?

[Ivan @ Southwest Speed]

Woah...heavy Q.

Prolly easier to find a turnkey and swap somebody for it.

My $.02,

Ivan

[grocerygetter]

nah....cam kit, lifters, afm disabled....done deal. That would surpass the LS3 given the cam avail. for the L99 already. Now granted...you could cam an LS3...but I really feel it would be STUPID to swap a L99 for an LS3 when the difference is really not that big if you do the above.

[mikel441]

L99 has different heads as well. Check out the specs here.

http://paceperformance.com/index.asp...&ProdID=249691

And here.

http://www.usmracer.com/LS3-62L-Gen-...e-_p_1970.html

[grocerygetter]

you port the L99s or port the LS3 heads...so what...

[grocerygetter]

short block is same

[mikel441]

The L99 uses L92 heads. I believe an L92 is a truck engine. Even if you port the L92 heads it will still have slightly different flow characteristics then even a ported LS3 head. The OP wanted to know if you could turn an L99 into an LS3. So yes if you change the heads and camshaft out. Remove AFM and some other minor stuff and I guess you got an LS3 with auto. But, Why? Just beef up the L99 and run what ya brung.

[VADER SS L99]

Originally Posted by Bad Karma

Woah...heavy Q.

Prolly easier to find a turnkey and swap somebody for it.

My $.02,

Ivan

no it would not be cheaper. I would contact a vendor like Mast or Livernois to get the details but the changes required would be LS3,ls9 or ls7 lifters. LS3 cam(but I would go with a better cam for more power)LS2 valley cover, timing chain and just a few other odds and ends. Tuning of course would be a must. You should ask yourself though if you are willing to give up VVT. Give it some time and the technology will be there for VVT. Keeping a VVT cam and losing the AFM would be a easier swap as the only things to change are the lifters and valley cover along with using a cam phaser limiter. I think MAST has the best VVT cams and even has 1 to where all you need to change is the cam for more power as it uses the stock lifters. The benefits of keeping a VVT cam out weigh the negatives for me in the long run. VVT should get better low end torque and top end power compaired to the traditional cam. It will also allow a bigger cam without some of the negative streetability effects. It will idle smoother and get better mpg. Either way you go you might as well get some ported heads as they have to come off for the swap. When tuners figure out how to tune L99 properly with aftermarket VVT cams and the cam companies start figuring out how to make great VVT cams it will be LS3 owners posting questions like "how do I convert my LS3 to a L99?"

[VADER SS L99]

Originally Posted by mikel441

The L99 uses L92 heads. I believe an L92 is a truck engine. Even if you port the L92 heads it will still have slightly different flow characteristics then even a ported LS3 head. The OP wanted to know if you could turn an L99 into an LS3. So yes if you change the heads and camshaft out. Remove AFM and some other minor stuff and I guess you got an LS3 with auto. But, Why? Just beef up the L99 and run what ya brung.

You are absolutly wrong about the heads. L99 and LS3 heads are exactly the same. L92 heads are the same as ls3 and l99 heads except for the valves and spring I think. If you had some L92 heads sent to a cnc porter and head builder and he cnc ported the L92 heads along with a pair of LS3 heads to exactly same specs with same combustion chamber size,valves and springs they would flow the exact same and make the same power.

[mikel441]

Originally Posted by mikel441

L99 has different heads as well. Check out the specs here.

http://paceperformance.com/index.asp...&ProdID=249691

And here.

http://www.usmracer.com/LS3-62L-Gen-...e-_p_1970.html

Did you read the specs on the L99?

Cylinder heads - 12629064 - L92 style port, 68cc chambers

LS3

Cylinder heads (P/N 12598594): LS3 rectangle port; as cast with 68cc chambers

Two different part numbers.

[VADER SS L99]

Originally Posted by mikel441

Did you read the specs on the L99?

Cylinder heads - 12629064 - L92 style port, 68cc chambers

LS3

Cylinder heads (P/N 12598594): LS3 rectangle port; as cast with 68cc chambers

Two different part numbers.

The part #'s are different because they have different valves. The bare head castings are identical. Take a L92 head and put ls3 valve hardware into it and you have a LS3 head. If you dont believe me just ask a vendor or ls engine builder.

[SGOS252382]

But why would you want to spend all that money for an extra 26hp?

You could just modify the L99 (heads/cam) and make a ton more rwhp than converting an L99 over to an LS3.

Don't forget - If the LS3 was put into an A6 (Automatic) Camaro it would probably make around 350 rwhp seeing that it makes around 370 rwhp in the manual.
With a nice head/cam setup on your L99, you could make 400+ rwhp easy.

[Andy@Livernois]

Originally Posted by grocerygetter

short block is same

actually the shortblock is different. The L99 utilizes valve reliefs in the piston for the exhaust valve where as the LS3 does not. But basically, it would take our DOD delete kit that we offer, along with an LS3 front cover to delete the VVT and the DOD out of it. Of course, our kit comes with your choice of cams as well to suit whatever it is you are looking to do power wise

[tony1]

Anyone doing this is crazy!! This was enginered like this and unless your an Engineer don't even mess it up. I see L99's out here stock or mod for mod running equal times... also you have to be dam good and fast with the stick to do it every time or the Auto will walk you.. the Auto has the computer shifting and your times will be very consistant..you won't miss a shift.