Mister Will

I am seriously considering doing a heads and cam package. I live under California's smog laws so I can't be too radical. My car will be mainly street driven.

While doing my research I feel myself being pulled in two general directions. Premium after market heads, or ported and polished LS6 heads. The after market heads have a geat pedigree with a premium price, PP'ed heads look stock with a practical price.

But my main concern is the volume of the intake runners and their effect on throttle response. Most aftermarket heads for my application have intake runners in the 205 - 215cc range. While most PP'ed LS6 heads seem to have runners in the 230cc range. Now big runners make for big flow numbers which translate to big dyno numbers. But my car will be mainly street driven with some spirited weekend driving, I'm more interested in better throttle response across the full operating rpm range and big heads can result in sluggish performance at low rpms.

So how much does the bigger intake runners effect low rpm throttle response. Should I be concerned about an extra 15 - 25cc increase in intake runner volume?

I know this isn't your typical which part is best question. But I appreciate any insight everybody can give me.

BTW, if this post looks familiar to some I posted it on corvetteforum's C5 tech section. I would like to get some more perspectives. Recent research tells me that with the right cam I could get the low end performance I want from p&p'd 243 heads with it's large intake port volume. But should I concentrate on teh smaller intake port volume aftermarket heads?

TXZ28LS1

iTrader: (5)

since cali is so damn strict bro, i would opt for the AFR 205 as i think they carry a legal CARB no, and run tony mamo 224/228 cam. proven setup for a fun street car.

transwiz

iTrader: (26)

You might want to consider using 5.3 heads.Patriot and PRC both have them on their website.They make good power under the curve and have good low end throttle response.
It's all about the parts as a whole.You want to have everything work together.Back up here.What are your goals?What is your budget?What parts do you have now? We need more info on this and where you want to go.

Old SStroker

What makes you say this? It isn't necessarily correct especially in the volume range you are looking at.

I suspect you are caught up in the "high velocity= low end torque and big ports = low velocity" idea. (I'd say "myth" instead of "idea" but that would probably start a poopstorm).

GM puts large intake port (L92) heads on 6L truck engines which have great low-end torque. How do they get away with those ~270 cc ports anyway? Perhaps they don't subscribe to "Internet Port Logic" (IPL). A few head/cam guys don't subscribe to IPL either.

Choose your H/C guy carefully.

Jon

Ed Curtis

Stop it Jon....

street demon2k3

iTrader: (3)

Don't mean to hijack thread but a friend is in a similar situation on head choice. He's debating on a sponsors ported stock casting over stock Dart 205cc's. He's looking for max power on we are sorta on the fence about what to choose for his setup which consists of a stock bottom end and a Torquer V2.

Im very interested about what everyone has to say about Op's original question.

Mister Will

I wont MORE POWER!! But all kidding aside I just want better performance from my LS1. Originally I wanted the same as an C5 Z06. This meant LS6 heads. Since ported LS6 heads aren't much more expensive why not. Then while I'm going to the trouble of taking everything apart might as well put the best in. I am willing to spend the money for premium heads ( for what people spend on vettes another $1000 isn't much). I'm building the fund now. I can afford to get aftermarket heads and a cam, pay for labor and all accessory hardware, and finally a tune. I want an aftermarket head with a CARB EO number. There are several out there (AFR, Edelbrock). Then there is the stock OEM looking 243 ported heads which have a practical price. BTW, I do a lot of spirited country driving/mountain driving with a group that includes a lot of C6 Z06s, and FI LS1/LS6 C5s. I want to do a better job of keeping up. I will stay N/A.

To give you the short answer, yes! It just seems that most aftermarket heads with ports larger than 225cc are for larger CI or FI applications. I don't think that the high velocity logic is a myth either.

However, some recent research has me wondering is the right cam will give me what I want from a bored out set of 243 heads. You see i want to be able to drive around the neighborhood as well has burning up the back roads. I want a beast but I want it obedience trained also. I also do not want to loose engine efficiency. I believe I can get great fuel efficiency with well designed heads, and if i keep my foot out of it.

I am talking to an reputable tuner. He has suggested the CNC'd LS6 heads with his custom cam grind. He says i want notice any loss of partial throttle response. I want to believe him. Is he right?

SOMbitch

iTrader: (8)

Dude..... Jon & Ed know and live this stuff so any advice they give (which isn't often and usually free) you will be well advised to listen too. Sorry but it is true.

There is only one sponsor on this board who is GREAT at porting LS6 heads. Some others are good and some not as good.... Great work cost big $$$ so understand that.... So what are your goals and how much you wanna spend ??? Feel free to pm if you want to.

Old SStroker

It depends on who he is. Does he also preach the "myth" you subscribe to? If he doesn't can you trust him?

Be advised that there a a number of "ported" LS6 heads available. Some are good, some aren't so good, and some are lousy. I suggest that the good ones will not be cheap.

Choose your H/C guy carefully.

Jon

Gh0st

iTrader: (3)

This thread hurts my brain.

Damian

iTrader: (89)

A set of 243's in the right hands can whoop up on almost any other aftermarket cylinder head available today.

Mister Will

Exactly the people I want to hear from.

I want a car with street manners, but can at least keep up with the big boys on spirited runs.

Here is a link to a video of a local run call Palomar Mt. It will give you an idea of the type of driving I'm talking about. The it gets to the mountain about at the 1:10 minute mark.

Palomar Mt. run by Carrera GT

I'm looking at heads CNC'd by West Coast Cylinder Head. My tuner suggested their CNC'd Edelbrock rare castings for LS1 engines. They are pretty good heads With excellent flow numbers. But I hesitate because they do not have a CARB EO number. I can handle non-CARb bolt ons. But it too much of a headache to change out a set of heads if you get caught by an inspector. So my tuner suggested LS6 CNC'd heads by West Coast Cylinder head (WCCH). The price is better and the look stock. But the intake port increase of 21cc worries me. I wonder about how it will affect drivability and engine efficiency. But recent research suggests that this might not be the case. I beginning to think Jon may have the answer to my question. At the moment I am taking a strong look at Edelbrock/Lingenfelter heads. They flow well, have an excellent pedigree, and a CARB EO number!

Mister Will

I would say no. He suggested the LS6 heads. Constantly mentions that it's the combination of parts that make the performance. He's build several 700+ cars for his customers. He's primarily a road racer, the cars he works on tend to win. He drives his own car and hold the track record at Spring Mountain outside of Vegas. Nobody questions that he knows his stuff.

I looking at the heads from the company in my post above. They are expensive without cores.

So, why should I not be worried about putting heads with big intake ports on my car? The LS6 heads look stock, and flow better than the Edelbrock/lingenfelter heads. But they have much larger intake port volumes. I'm afraid this could lead to low partial throttle response (street driving/cruising), making the engine unspectacular below 3500 rpms. So yes I want high port velocity for low end performance. If I am wrong tell more or direct me. I have an engineering background and do get it.

Thanks for your input!

SOMbitch

iTrader: (8)

I was refering to CAETEK as the sponsor on here.....

OP if you want another name PM Jon and ask him. He knows somebody who can get you a pretty good set of 243 heads

00Camary

iTrader: (15)

Cali sucks for that. If you are worried about emissions why not go to just a stock 243 head. My car gained roughly 30 rwhp with just the head swap from stock 241's. The cam is going to be the ultimate decider on power. Remember bigger isn't always better. Dunno about all this wcch talk .... not from there. Patriot and afr are good choices. AFR if you got the money. I would go with a sponsor on here such as TSP or similar. They can guide you to get you what you are looking for.

Nitroused383

iTrader: (10)

Its kind of sad we never see results anymore from TEA LS6 heads or WCCH ported LS6 heads. All you see is tsp head dynos and well most results are less than my non ported 243 heads. If you look up threads from 03-05 you will find very impressive results from TEA LS6 heads. 450rwhp with LS6 intakes and a good cam was the norm. Fast forward 5 years and now guys are having a hard time doing that with FAST intakes. Your engine is an airp pump and your cylinder heads are by far the most important componet to pumping the most air possible. Oh ya do LS3 engines have poor throttle response... 260cc intake runners, must be pretty crappy velocity??

Mister Will

WCCH makes the Edelbrock heads that A & A Corvettes sell. BTW, I have the money for AFR if I want to spend it.

Wasn't aware of that. I'm not that familiar with LS3, but they do have a slightly larger displacement. I wonder what the cam profile is?

Then again LS3 heads are designed that way. CNC'd LS6 heads are bored out, possibly leaving excess room to create turbulent flow?

flintwrench69

iTrader: (11)

I plan on getting a set of heads, most likely some 243s by spring & possibly having them ported so I have been thinking about this also. I got a price from a local guy that was recommended to me, he says $800 to port them. Now I have no idea where that is in the ball park of what that usually runs to have them done right. Whats a better value, buying a set of 243s, having them ported or buy a good set of heads like some trickflows or AFRs that are well known for great flow & holding their resale value? If I pay $500 for some used 243s & got $1300 into them after porting, what would they be worth later on if I decide to sell them? After hearing how much better the 243s flow, I am thinking just buying them & bolting them on would be the way to go.

Old SStroker

I don't think you are a candidate for any of the real head guys, like Richard, or Ed or others who shall remain nameless. They actually know lots more than you do about these things. They may tell you things you don't want to hear. Some already have.

I think Yogi Berra said it very well: "There are some people who, if they don't already know, you can't tell 'em."

Gotta' love Yogi.

Good luck.

Jon

PREDATOR-Z

What they are trying to tell you will is that it is not the size of the runner that determines low end response, but the velocity those runners have. Meaning it is not necessary to have small runners for good bottom trq and response.
The runners along with short radius, chamber to bowl transition and VJ have to be done correctly, that is all .
The LS3 heads have been derived from LS7 tech and are masterpieces for being in stock form and the price they cost. The only problem, they need at least a 4.00 bore, so in stock castings, 243/799 are still the best bet for a LS1/LS6 bore.

Here are links to give you more insight:

http://www.popularhotrodding.com/tec.../velocity.html

http://www.gmhightechperformance.com...ads/index.html