Crew_Chief

So I am starting a parts list for a 408 build after my next deployment still trying to gather information tho. My goal is 650 rwhp n/a and add nitrous in the near future. It will be going in to a 99 camaro.

Not too worried bout the weight so I will be going the LQ9 route.

Forged 4340 K1 crank and H rods with 2k apr bolts. Still trying to decide which pistons to go with. I’d like to stay around 11.5:1 or 12:1 CR so I’m thinking i should go with a relatively flat piston. I know the deck height, head combustion chamber and gasket will play a part in the cr.

As for heads I’m thinking a LS3 PRC 260cc. Or would it be cheaper to get stock 317s and send them in somewhere for a custom port? .650” dual springs with titanium retainers. Haven’t really done much research on rockers or valves so your input will be appreciated.

As for the intake I would really like to run the Holley hi ram but from what I have read there is a lot of clearance issues… if what i have read is true I can get rid of my ss hood if need be but i don’t really want to cut into the glass just for an intake. Would the mid ram fit better I believe it sits 4” lower than the hi ram and if I remember the flow of the mid isn’t much less.

Not sure wether to go with a 92mm or 102mm tb I have read where some have had tuning issues with the 102mm but i thought the more air the better.

After heads and intake are decided I plan on getting a cam spec’d.

Any other info/opinions y'all can provide will be greatly appreciated!!

Tuskyz28

I just don't see a 408ci making 650 at the tire on pump gas... I may be wrong but I personally just don't see it happening.

Tuskyz28

The LS3 heads aren't as good as people think they are either.....
I've seen results where a tfs/afr out perform bigger rectangular port heads.

Crew_Chief

If I can get close to 650 I'd be happy. I read where the holley intake sits a tad lower with the square port heads. Thats the only reason I considered them.

Tuskyz28

Is you stuck on running pump gas ?

I've seen a 408ci with afr 245 heads make 630 at flywheel using a 240/246 cam. Intake was a truck fast 102mm setup. Pump gas motor at 11.5 compression or so. Motor featured on super Chevy website.

Crew_Chief

I have hopes of running E85 there is plenty of it where I'm stationed.

NIKDSC5

iTrader: (10)

You can hit 650 crank, but not at the wheels. Not NA. Going through a 6sd or auto? An all out 418 build could maybe get you to near 600 whp, but I have never seen a 408 crest 575whp with out help.

Tuskyz28

I highly recommend you consider getting in contact with HKE.... no one I've seen yet across LS scene make a 408 run like Erik does.

Crew_Chief

I guess I'm a little too ambitious then... What would be a more realistic number to shoot for?? I read where pat g made 500 at the wheels with hci ls1 so I figured the 650 would be obtainable with a 408 with the right top end. I have a built 4l60e for now.

Tuskyz28

I've talked to Pat G more than once on the phone... he'll tell you what I'm telling you. 550 at the tire seems to be a great number to shoot for. Call him and see what he'll tell you about those LS3 heads compared to aftermarket heads such as tfs/afr/mast etc....
Can't spill all the beans cause I don't want to get banned LOL

NAVYBLUE210

408" E85, 700+ FWHP 580-600 RWHP through auto. Tough but
Possible. I would talk with Tony Mamo @ MMS.
MMS 235s with NFI exhaust port & lightened valves, MAMOFIED LSXRT (truck intake),
(The BEST Fuel Injected Intake currently available) CAM MOTION
Low Lash Solid Roller Cam Shaft, Need peak HP RPM 7500+
Something like 259*/267* .700"/.680" LSA ?
14.0:1 Compression Ratio, at least 1 7/8" probably 2" Headers, with
3" True Dual Exhaust,
Just my .02

blk00ss

iTrader: (66)

How much does tony pay you?

NAVYBLUE210

$0.00 LOL!
Tony is a good friend and I have seen his Engine Builds and
Heads, Intakes perform exceptionally well multiple times.
Not saying others won't, just throwing my .02 in for consideration.

Did you ever reach your 600 RWHP #?
You were talking about a MAMOFIED 102 FAST at one point also
If I remember.

03EBZ06

Realistic = < 550. If anyone tells you different, ask for the car wt and MPH in the 1/4 and the true hp can be calculated. A 550 rwhp motor is a great running car. This about like the current C7Z. 3700lb car 129mph.

How do you figure that intake is the best currently available? I have personally seen a Holley Hi Ram make 40rwhp over a FAST102.

blk00ss

iTrader: (66)

Not yet. Maybe one day I will. Just keep throwing money in other places.

NIKDSC5

iTrader: (10)

And have the worst street manners available.

KCS

iTrader: (20)

I agree, that Hi Ram is probably the best off the shelf manifold as long as you have the hood clearance for it. On the cathedral stuff, I think it tapers down to only like 2.5 sq. in. so for big power applications, I would think it needs to be opened up.

Crew_Chief

So without lowering the k member would I have to cut all the way into the windshield to get the hi ram to fit??

Crew_Chief

Thanks for all the info!! Would -3cc pistons be a good choice for a 200 shot and what would be a good cr for nitrous??

speedtigger

iTrader: (16)

I have seen a similar engine with square port heads make 700+ Flywheel with similar cam, compression and pump gas. I will be sharing somthing very soon that may change your mind. Stay tyned.