Need help with a 408 build

[mr2cam]

Hi guys, im new to this forum. My dad has a 99 Silverado shortbox that currently has a 5.3 in it right now, the 5.3 has about 180,000 miles on it and my dad wants something with more torque and power. He ended up buying a junkyard 6.0 (LQ4) that had about 200,000 miles on it, it does have aluminum heads. Anyway he is shooting for about 400/400 (at the crank).

He has his heart set on a Eagle 408 stroker kit, and with the heads he has (I believe they are 71cc heads) he would be right about 9.7:1 compression and hopefully still be able to use unleaded regular gas. The block is iron (I believe all LQ4's are?), one of my questions is will boring it 40 over be safe? He read somewhere in an article that they shouldn't go more then 10 over, but I believe that was on an aluminum block 6.0. Also he wants a cam that isn't lopey and makes good bottom end power, he uses the truck basically just for daily driver and he towes a lot with it, but we also take it to our local track sometimes to have some fun. What kind of cam would be ideal for that type of stuff? Thanks for the help guys!

[Frenchy]

bore it .030 over will get you the 408, .040 over will get you a 410. But I'm a big fan of boring it out the bear minimum, the extra cylinder wall thickness is better then the couple extra cubes gained

[mr2cam]

bore it .030 over will get you the 408, .040 over will get you a 410. But I'm a big fan of boring it out the bear minimum, the extra cylinder wall thickness is better then the couple extra cubes gained

Perfect, looks like .30 over will work, now I just need to find a good streetable cam and we should be set!

[mr2cam]

Also does anyone know if the Eagle kit is good? Were not using the truck for anything too crazy, mainly towing and daily driving and a little bit of 1/8th mile track racing.

[Madd Maxx]

Eagle makes quality components. Also check out Scat for good bang for the buck.

In a 408, this cam will provide loads of low and midrange torque, idle fairly smoothly, and pull hard to about 5600 RPM:

212/218 0.522/0.529 114

COMP Cams: XFI™ RPM, XR265HR <BR> Good Torque and Very Strong Mid-Range Power, Good Performance Cam.

[Frenchy]

I'd say that cams a little on the small side for a 408, I'd go up to something in at least the 224 range

[truckinL33]

Yea, you have plenty of cubic inch. I would go with a cam also in the 220's. Depending on what heads you have for the engine, a 220's cam and full exhaust will put you over 400 hp and 400 tq.

[Madd Maxx]

I'd say that cams a little on the small side for a 408 . . .

Not based on his stated requirements:

He also he wants a cam that isn't lopey and makes good bottom end power, he uses the truck basically just for daily driver and he towes a lot with it, but we also take it to our local track sometimes to have some fun.

The cam I suggested would fill his needs nicely, and preclude the need for a higher-stall converter. A 408 with 317 heads and that cam would make about 425 HP and 450 lb-ft torque. He's after torque, not upper-RPM HP.

Some people say that the LS7 cam would work well.

No, that would be a mistake. The LS7 cam has a very late intake closing event, which would kill your bottom end. It was designed for a high-revving, light vehicle (like a Vette).

[truckinL33]

I agree with madd maxx, and those numbers he's suggesting are probably wheel power

[mr2cam]

Some people say that the LS7 cam would work well. Also while were on the subjet, for that much power what size of injectors will I need and what fuel pump? Thanks again for the help!