96birdlt1

I am looking to get heads and a cam in the near future and can't decide which route to go.

I want the most power I can get while:

1. staying within emmissions

2. both on and off the nitrous

Should I port and polish the stock heads, get a set of AFR heads and get them port and polished, or switch to the LT4 heads and intake and get those port and polished?

Joe94Z

I wanna know these questions too.

96birdlt1

ttt

Fastbird93

Factor in a couple of things. First, AFR heads are expensive. Lets say average about $1500 for a set of bare castings. Then, you have to pay to P&P those. Suddenly, you're talking about $2500 for a set of heads that flow somewhere around 280-300 CFM. Or, you can buy a set of LT1 castings for $250, and have those ported. I went that route, and paid a grand total of $1550 for a set of heads that flow 281@.550, and no less than 268@.450. Intake runner size has a lot to do with airflow velocity, something I'm not too good on. Someone will chime in. Basically, you don't want AFR 210's on a stock displacement LT1 because it would kill the velocity of the air coming in.

Staying within emissions is all about the cam and a good tune. Some people are going with a cam that won't pass emissions on a "street tune", but do a special emissions tune and pass.

In either case, be prepared to spend some bucks. My total head/Cam investment is $5200. There's a lot of small stuff that you don't expect, or didn't already have.

llafro

The size of the intake runner affects how the air flows at different engine speeds. At low engine speeds and small engine sizes, a smaller runner is better because it produces higher flow, and higher air speed. At higher RPM and with a bigger engine, you need the bigger port to flow more air.

It's like a garden hose vs. a fire hose. Turn on the garden hose full blast and you can easily wash down the driveway. Now put that same amount of water through a 3" fire hose. It would probably just dribble out the end and you'd have trouble washing the driveway. Now, if you can get a lot of water to the fire hose, suddenly your washing will become really easy. But putting that kind of water into a garden hose won't do much because it's already maxed out.

Heads work the same way (more or less). With a smaller intake port, you gain low end throttle response and torque, but sacrifice some high end, because the port can only flow so much. With a big port, you sacrifice low end response and torque for high RPM flow and power.

Engines are all about compromise. You have to sacrifice some things to get more in other areas. Make sure that your compromises work together, though.

got_hp?

care to itemize how exactly you spent $5200 on heads/cam?!?!?!?!?............i think you meant $2500 right?

heads $1500
cam, springs, rr's, etc $700
gaskets and misc small items $200

96birdlt1

So P&P'd AFR heads and P&P stock heads will flow near the same. Then what about LT4 heads and intake? Would I be better off with those or LT1 castings?

I guess the Hotcam would probably be the best bet on the cam? Any suggestions on that?

Ai

Unless you're trying to make more than around 525hp NA, i'd stick with the LT1 cylinder head casting. Most peoples billion cfm LT1's actually flow in the 25X range.. pretty obvious b/c they make pretty good power, but not a ton. The AFR route is going to cost you $1050-1100 or so for bare castings, but there's so much work in going from bare to a killer head that by the time you put all the components/machinework/labor into them you'll likely be over $3k. There's alot more to it than actual porting . Alot of guys run mediocre parts.. crane.. manley.. stock seals.. bleh. Most don't spend the time to install bronze guides, or bronze guide liners - much less hone them to the proper clearances as opposed to poundnig a ball broach through them to open them up. Spend $ on quality components, it's worth it.

Depends on what you want, but if you're stuck having to pass emissions and whatnot I wouldn't put several thousand in a set of heads.

Figure you'll have $400ish in head components, $250-300 worth of machinework, labor, around $800 in (timing set/cam/pushrods/rockers/guideplates) & then $ for misc. stuff like gaskets/fluids/tuning/etc.

Money money money .