Sorry if this sounds stupid but this is my first engine build.I have a ls6 in my 2000 firebird that me and a friend built. It has a small cam and is bored 30 over. I have a ls1 intake and 862 heads. Bty I'm not trying to build anything crazy just something to play with on the street. I had it tuned and ran on a dyno. It made around 380hp at the wheels. Like anyone would do i asked the tuner what I could do to make more power as I was wanting around 450. He told me if I put a set of ported 243 heads and a ls6 intake with a good throttle body it hould be close to 450hp at the wheels. Before I go blowing money on this I was wondering if what he is telling me sounds right. I just don't want to blow a couple thousand to not gain much. Any advice is appreciated

 

I'm just a bit confused on your current setup. You mention having an "LS6", but then state that it has 862 heads and an LS1 intake. What happened to the 243s and LS6 intake that would have originally come on your LS6 engine? Did you just start with a bare block?

And what is the current state of your 862 heads? Are they stock (as cast) or have they been worked? If it's a stock 862 and you move to a well ported 243 plus an LS6 or better intake, there would certainly be plenty to gain.

Just want to make sure that we all understand what you're working with here.

 

Well first off you're not boring any LS1 or LS6 anything .030 over, so there's that. That'd be some thin Cylinders..

Sounds to me like you all took a LM7 5.3l Truck Ironblock Engine and built something out of it. Elaborate more on exactly what you have then we can move forward.

 

Sorry it's a ly6. Yes I bought just the block. Had the heads and intake laying around so I went cheap and just used them. As far as the boring all I know is what the engine shop told me. He said he went 30 over and 60 was the max. Sorry it took me so long to reply. First time on here and I couldn't find my post. Again this is my first build still dumb on allot of things. Thanks for any help

 

If that helps any

 

So I did some research and it is an iron block ly6. Bored 30 over with a small cam. New update as you can see by the cylinder pick i took the motor out because after 1500 miles it was starting to smoke a little. Looking at the cylinders 6 have scratches that I can catch my fingernail on. I believe this is due to putting in bigger injectors and doing 4 break in cycles around 10 to 15 minutes each before i took it to my tuner. I could smell it was running rich but thought it would be OK it was bad enough i fouled a set of plugs after the second cycle. I believe I washed the cylinders doing this. So with that said I'm going to take the block to a race shop in Ohio and see if the block can be bored enough to clear the scratches. If it can I'm still going to do the 243 heads ported and ls6 intake. I also have a volant filter system. I have decided that I'm going to stroke the motor to a 408 i believe. I wanted 450hp to the wheels and I figure a little more won't hurt. Im thinking it will be around 500. Sorry this was so long. What do you guys think it will be?

 

Running rich isn't going to gouge metal, something else happened.
If you are going bigger than that 370 the 243 Heads and LS6 Intake with a bigger Cam would definitely be an improvement.

 

Yeah i am kind of afraid that it is something else which is why I'm taking it to a shop to be checked out. I wasn't going to spend this much but I really do enjoy the car puts a big smile on my face every time I take it out. I'll post the dyno when I get it going again. Going to be a a little while though. Hopefully this fall. And thanks guys for not tearing me apart on this.

 

Her are a couple pics

 

One Eye, I think you will struggle to hit 500 wheel with that 408 set up. I just built a 408 with AFR Mongoose heads, 235/243 .621/.624 and a FAST 102 and put down 483RWHP. You should easily get to 450 though.

 

Fyi......a bolt on ls6 is capable of 450 to the wheels.

So realistically anything beyond that should make more. You don't need a 408 for 450whp......it's sad that many only expect that.

my 5.7 made 548whp 444wtq. A 408 should easily top it.

 

That's underpowered, check into the tune.

 

So small but good update. I dropped the motor off at my builders and he thinks it can just be honed. He also said it looked like something got past the filter and he did not like the fact that I did not have forged pistons. Said maybe a ring broke. He is pretty booked up but will get to it soon. My advice when building a motor don't go cheap *** like I did. More to come if anyone is following

 

Another dumb question. I have a friend with a boosted firebird and he turned it up and blew the map sensor out of his fast intake. Would this be worth buying and trying to fix?

 

Where is the MAP Sensor located on it? My LS6 Intake I have in my SS I traded a 12-pack of beer for because the tab was broken to hold the MAP Sensor on. Ziptie holds it on fine.

 

Merv, I thought so as well. I was fully expecting 500+. Especially since I also have a Fast 102 and a 25% underdrive pulley along with the 230cc AFR Mongoose heads and 235/243 0.621/0.624 cam. I also expected to make max power at higher than 6120 RPM. I used Complete Street Performance for the tune and they are usually really good at getting the most out of the combo.
OP, I apologize for hijacking your thread.