B'klyn9C1

What I mean by "semi-budget" is that I am willing to buy a junkyard high mile L33 but instead of just flopping it into my car I would have it rebuilt with a machined crank, LS3 rods, fresh bearings and rings, fully balanced rotating assembly and ARP fasteners everywhere.

I know this type of question have been asked on other threads but the answers seems to always come back kind of fuzzy.

The power goal is 600 to 700 RWHP in a 1995 Impala SS/Caprice daily driver street car.

Bottomline: Are ported stock 799/243 heads or even aftermarket TFS's or AFR's heads worth the expense on such a build or shall just forget about it and turn up the boost an extra 1 or 2 psi????

stevieturbo

CNC ported heads are not expensive, so it's hard to say that they arent worth it. Especially as they'll come with better valves and springs already.

They will help power/torque both on and off boost. So a lot will depend on actual usage too.

TurboMonte100

iTrader: (1)

The hp level you are wanting should be easy to reach with stock heads, check out the thread about the Fairmount. He made the numbers that you are after, and I think he even had two different casting heads.

The poll posted is some what vague and with the goals you stated it does not completely apply.

I would find a good buy on a useable set of 243/799 and go.

B'klyn9C1

Two good points Stevie!! Thanx but you should have voted for the first on the poll.

You know there is a school of thought that says the stuff that makes a good N/A motor like good if not great flowing heads, intake and exhaust does not apply to FI motor esp. turbo motors.

TurboMonte100

iTrader: (1)

With a turbo, the air flow works entirely different than when na. A na engine relies on the cylinder to draw air in, with a turbo there is always constant pressure blowing in.

That said, NA or turbo, any means to increase air in and out is never a bad thing. To directly answer the OP's question. Yes you can reach your goal with bone stock heads, many have done it. I am currently building a 5.3, my goal is around 1000hp and I am using stock heads with stock valves that I ported myself.

stevieturbo

Re-worked heads to offer more flow is never a bad thing, unless it's via huge ports which reduces port velocities, or badly shaped ports regardless of flow..
For a turbo setup, yes you can ram more power down their throats, but even a simple clean up, better valves and springs is a very cost effective improvement.

The key is value for money, and most of the ported head offerings are very good value in my eyes. So there really are no negatives.

You could make all the power in the world with stock ports one way or another. It doesnt always mean it is the best approach to doing so.

Twin turbo c5

Just boost it and have fun. lots of us are making power on stock untouched heads. I just made 670hp on a set of stock untouched ls1 heads with 14 pounds of boost. Save the time and money and go have fun and do some burnouts.

71 chevy

iTrader: (18)

take the money you save by running the stock heads and buy forged rods and pistons

novaflash2002

iTrader: (51)

^ 2nd that

subliminal

I'm in a similar situation, im in the process of a pt88 forged 408 build and cant decide if i should just spend a $100 to clean up my tfs 215's or a $1,000 to completely port them and larger valve's? from what iv just read it seems like i could just add 1psi and it would be the same

nick.celis

iTrader: (11)

just turn the boost up!! i have ported heads, and it made literally no differnce, biggest difference for me was changing to a custom grind cam, with my turbo setup i cant see ANY difference with the ported heads

subliminal

Thanks for the reply man, the guy that does my heads made it sound like it would be a world of difference like 100hp on 15psi, but he is one hell of a sales man...

71 chevy

iTrader: (18)

i think there should be a rule : dont put expensive heads on boosted junkyard engines:

1. if your engine lets go, you more than likely just trashed your expensive heads
2. if you spend the money building the bottom end, you can make 400-600 more hp by turning up the boost- or you could put heads on instead and only make 100 more hp.

i vote that this should be an ls1tech forced induction section, plain old vanilla common sense rule.

71 chevy

iTrader: (18)

by the way, i have the worst flowing ls1 heads ever made(stock 862), and on 12 lbs my engine is still making over 800hp

subliminal

So my 10:1 408 with tfs 215's and a properly matched cam with E85 at 15psi should lay down some number's then?

71 chevy

iTrader: (18)

at 15 psi, if that doesnt make close to 1200 or better, something is wrong.

LilJohn

Good god at the advice given in here...

Proper head sizing still matters with a turbo...

215cc tfs on a 408? Probably gonna choke out by 6000 rpm.

The laws of physics still apply to a turbo...

800 hp.. with 862's... with 12 psi... on a 6 liter???? Cmon man....

71 chevy

iTrader: (18)

haha, "say it aint so john". there you go again, urging people to spend money they dont need to spend.

stock ls1 heads on a 408 made 550 peaking at 6200. at 15 psi on e85 , thats 1100hp.

procomp heads with a 219 cc runner did 629. thats 1258 at 15 psi john.

http://www.hotrod.com/techarticles/e...t/viewall.html


actually, i said 800 TO BE CONSERVATIVE. the combo is 900+ hp, AT 12 PSI.

please advise, what 3000lbs, with an mph of 117.4 in the eighth, is making for hp, then what if i showed you the datalog that shows full throttle for only the last 2.0 secs of the pass? you tell me how much power that is showing. i dont do shoulda coulda wouldas. thats why i said 800. the timeslip can back that up. the engine is making 900+ on 12 psi, with factory stock 862 heads that i bought for $100.

hint
http://www.rehermorrison.com/PdfFile...eriesHP_ET.pdf

FURTHERMORE,
what is so special about a 6.0 on methanol making 800hp on 12 psi? if my engine were making only 800hp on 12 psi, being a 1.81 pressure ratio, that would mean my engine is only making 440 NA at the flywheel. LOL, and i would have every right to be pissed, when ive seen 6.0s make that to the wheels.

only 440hp with methanol, a cam and a vic jr intake? get outta here with that bs.

LilJohn

Do you understand the concept of sonic choke as it relates to engines and intake ports?

Blackpanther99

iTrader: (8)

5.3 heads will hold some good power. You can use that money for something else.