oakley6575

iTrader: (3)

Hey guys, so this summer I got my 408 built and its in my truck. Turned out good and runs solid without any issues. Here are the specs:

408ci LQ4 Short block
Callies 4" crank and 6.125" rods
Wiseco flat top 11.5 compression pistons

Stock LS3 Heads
Stock LS3 intake
231/239 114+2

With this combo through a 4L80e Silverado, it made 434whp and 400wftlb. Good not great... I would think the torque numbers would be a little higher but it runs strong. Obviously the H/C/I combo is really holding this project back.

I want to get everyones opinion on a cylinder head that will wake the numbers up.

Duffster

iTrader: (103)

L92...

oakley6575

iTrader: (3)

? Did you read my post? I have LS3 heads on there right now.

01ssreda4

iTrader: (96)

Something/anything ported. That motor wants to breathe.

PREDATOR-Z

TFS or AFR

oakley6575

iTrader: (3)

How big of a runner could I run. This is a daily driver. But I don't want to leave power on the table. Is 235cc too big? 225cc?

Lambert695

iTrader: (17)

AFR 215cc and a Fast intake. as stated above... that motor wants to breathe!

JS01

iTrader: (10)

The new AFR 230's or TFS 235's would be nice. Almost any of the MAST deals too. Put a FAST LSXrt on there too.

oakley6575

iTrader: (3)

Yea when I get heads, I will for sure get a fast intake and cam to match. Any ideas how much horsepower/torque AFR 230's Fast intake would produce.

studderin

iTrader: (28)

Mozes

Jim85IROC

iTrader: (6)

I don't think heads are your problem. Stock LS3s with similar cams are putting down way more power. LS3 heads on a 408 should be a 500RWHP combo.

oakley6575

iTrader: (3)

Yes, through an m6. 4L80e's are extremely robbing. I figure I'm making around 550 at the crank. Right where it should be with stock heads/intake and a small cam.

Also the tuner didn't spend much time on it. I was pretty disappointed. He didn't tune for different injectors or anything like that. I think he only played with the VE table and timing. So i'm trying to learn the tuning part of this motor as we speak.

Duffster

iTrader: (103)

If you don't like your heads... when you get more, wanna sell them to me?

HTX

iTrader: (1)

AFR if you have a good budget.

KRAZY K 2000 TA

iTrader: (5)

AFR heads and fast intake and throttle body,GOOD tune!!

reeperz28

iTrader: (1)

Send your heads to advanced induction im sure he can fix you up with a cam too.

SOMbitch

iTrader: (8)

Yes there are better heads but your problem is not with your heads. Get it tuned correctly first and see where you are. I have seen a good tune pick up 30+. Also what exhaust are you running and are you sure lifter preload is correct? Unless you are just on a stingy dyno those #'s are pretty low. My old 346 made those exact #'s on a smaller cam.....

Detoxx03

iTrader: (14)

First off I thnk your cam is too small for a 408 but for heads I would go with some TFS 235's. If you don't have a FAST intake you should look into that too

OldCobraGuy

iTrader: (2)

At your altitude and air, and being in a truck, you need grunt (torque)...not just hp. The best way to create that is with velocity through the intake tract. I'll bet you that AFR would recommend their 205 cc heads. I would be shocked if there was a significant drop in top end, but the bottom end would be a bunch better due to the increased velocity through the intake ports. This is assuming you have good headers and exhaust. I have a lot of experience running at 4500 to 6000 feet in elevation. This will help. You may be nowhere near that elevation, but in Las Vegas, I can guarantee the density altitude will be way up there most days.

oakley6575

iTrader: (3)

Yea thats funny, those were my exact numbers. I was trying to run 1.875" headers and they didn't fit my truck so I had to overnight some replacements. They only thing they had were Pacesetter 1.75". From there I'm running 3" to a dual inlet Magnaflow, and a single 4" out.

Obviously I need to buy a wideband and tune the truck myself.