earmuffs

have a couple thousand dollars to spend on a motor alone. Do i build a 408 forged lq4 with 243 heads and ls6 intake? or do i get trickflow heads and fast intake and do a cam swap on my stock cube ls1?

need advise?

soundengineer

iTrader: (16)

no brainer.. get the forged 408
it will make more power than the 346 with upgraded parts


down the road if you decide you want more power still, you can always still upgrade the heads and intake.


plus the fact that its a new motor... thats an extra 150k miles you just gained yourself.
and being forged means you can give it more punsihment with less chance of failures...
get one ready for nitrous and have some fun with it.

soundengineer

iTrader: (16)

and dont forget to get new lifters with the new motor....preferably some Comp/Morel lifters and not just GM stock lifters

earmuffs

why do you say new lifters if im going to do a mild cam, will new lifters be needed?

soundengineer

iTrader: (16)

if you are going to have the heads off.. and you have any kind of mileage already on the existing ones.. why not just play it safe and put new ones in.

why limit the life of your engine by reusing an old lifter designed for a stock cam profile.

yes people run the stock lifters with all sizes of cams...
but mild cams arent always mild lobes and can be hard on stock lifters.
anything different than stock will be more harsh on the stock lifters.
it will decrease the life expectancy.

so get some good ones and play it safe and have a long engine life.

1QWIKBIRD

iTrader: (25)

What is the actual budget? It sounds like you are asking whether to put your current top end onto a 408 or put a really nice top end onto your cammed shortblock?

Tough call. What's the ultimate goal? How many miles on your short block and what kind of condition is it in? How long until you could put a nice top end package on the new short block?

I think either option could spill into the $3500+ range without trying too hard at all.

Chris

earmuffs

here is the two options.

408 lq4. already have a machined block - spent 500 bucks can get that out of it
243 heads have sale pending for 440 can cancel that or buy them with prc dual springs for 700 installed
LS6 intake and TB off of current motor.
Callie 4" crank, 6.125 rods, wiseco flat top -3cc heads. 2k
236 XER cam on a 114 LSA from comp cams $350

-OR-

01 LS1 m6 vette 80k miles.
TF 205 heads 58 cc chambers. Fast 102 intake and throttle body
possible custom grind cam.

Regardless of which route i go A&A headers and Spec stage 3 clutch with HD t56 rebuild is going to happen.

The budget is whichever route will get me closest to 500 rwhp cheapest.

180ls1

iTrader: (4)

what are your goals? I am not too sure if you know what your getting into (in terms of cost) when building a proper 408.

$2000 wont get you there or even close for that matter when it comes to a 408.

earmuffs

2000 isnt my budget. my budget is maybe 6k

1QWIKBIRD

iTrader: (25)

I'd wait for some of the more experienced guys to chime in and talk to some of the sponsors assuming you are playing with $3500 or so?

My guess is that the 408 combo will be held back with 243 heads (stock un-ported) and probably won't support 408 cubes all that well, especially with an LS6 intake. But the new short block lends itself to bigger/badder things going forward and a top end swap down the road is easier than swapping a short block down the road.

The TF heads/Fast/custom cam combo could put down some really nice numbers on a 346 (many have already proved this) and maybe (big maybe) put down more power versus a 243/ls6 equipped 408?

If its my money, I'm putting the best heads/intake/cam I can on my shortblock, assuming its in A-1 condition with no problems or flaws, at that price point.

heads $2400
102 Fast intake/TB/fuel rails $1500
Cam $400
Lifters $125 (ls7)
Tune $500
Injectors $250
Rockers $500

That's $5,500 pretty easily.....

The crippled top end on the iron 408 just isn't as attractive to me. A properly built 408 is going to approach 8K+ pretty quick. The 408 is all that same stuff plus the short block $3500?

I'd do some more homework to get the most out of your budget. Don't end up with a lame 408 that only puts 430hp to the rear wheels. That'd be a shame.

LT1TA

iTrader: (17)

i like you qwikbird, but you're ruining my damn dream! lol, i'm making my own thread and pretending i havent read this.

earmuffs

how did you get 3500 for the shortblock? I have a block machined already and im only in 500 bucks. rotating assemblies are 2400 for a high quality setup, 2000 if you go eagle or scat.

8k for a 408 isnt what ive figured, mainly because once its a long block, everything from my 01 ls1 will just move over, minus injectors. here are the numbers.
2500-2900 for a shortblock.
700 heads (243 with prc dual springs and stock rockers)
500 for cam lifters and push rods
200 for injectors
300 for gasket kit and bolts
intake, all eng covers from ls1

4600 for 408. all labor being done by me and 3 friend with enough engine experience.

xxcov3rxx

iTrader: (1)

I a interested in this also. i'm building a 408 with tsp rotating assembly and was contemplating putting on the stock 317 heads with ls6 intake. but if that is going to restrict it a lot, then which heads would be suggested?

even with a 408 243s and intake what kind of numbers can earmuffs expect?

1QWIKBIRD

iTrader: (25)

LS2 Lifter Trays $30
LS2 Timing Set $58
Oil Pump $140

So now you are at $4800

Trunion uprgrade for the rockers? $150

Tune $500

Your at $5500 by the time its all said and done or very very close to it.

I'm not saying it can't be done. I'm betting it won't be an optimized combo. A set of stock 243's won't let 408 cubes see their full potential. Ditto on the LS6.

Not wishing ill will, not at all. I'm just saying that there lots of costs that sometimes get glossed over which can end up killing a budget or forcing you to really handcuff an otherwise nice combo.

Good Luck.

earmuffs

i know the 408 wouldnt be able to breath as nice as it could. however, it has room to improve. the 346 would be all but done with that block. na ofcourse

1QWIKBIRD

iTrader: (25)

I agree. So really the decision needs to be made if future upgrades are going to occur? If a bigger better top end is possible a year down the road, then build the best shortblock you can afford now. That may still be the better of the two options, because you end up with a fresh zero mile build.

From the perspective of making power right now, I think the same amount of loot applied to the 346 (assuming its in good health) could net more HP at the wheels, as crazy as that sounds. It might be a more aggressive sounding motor, but could make more power because it would have far better cylinder heads/intake which would allow better airflow = more power.

If you scan through the 408 builds, you will see that the guys who run the better heads are the ones who more fully reap the rewards of the extra cubes. The big power is in the cylinder head flow. All of this is under the assumption the motor stays NA.

I don't think there's a wrong answer, just don't be surprised if the 408 doesn't put down the magical 500 RWHP. I still say that a full on 408 build requires in the neighborhood of 8K after all costs are taken into consideration.

Maybe the middle ground is to send the 243's out for a CNC port job?

earmuffs

going to go with speed incs, head package will put me at around 6k total fo 408 with good, not great heads and ls6 intake.

$1900
cnc patriot 243s with 650 lift springs
custom comp cam
pushrods
gaskets and head bolts

xxcov3rxx

iTrader: (1)

With this combo what would the estimated power out put be... i guess you would need a cam spec huh..

earmuffs

236 XER cam on a 114 LSA is the area of cam im looking at