The Sportsman IIs claim to be able to handle 450hp out of the box.

But, couldn't most heads, I mean you could just slap a blower or some nitrous on most heads and get to 450hp without much problem, right?

So, why do they mention this, unless I'm reading into it wrong, and they really mean NA..

 

I'm sure they mean NA. However, getting '72 2-bbl 350 heads to support 450 HP on a 350, even with power adders, could be a challenge.

 

I guess thats the factory rating, (their recomendation)
wich is with out porting..

 

Out of the box, bolted to a engine with matched heads/cam/intake the heads can make 450 hp. I don't think anybody tells you what you can make with heads under forced induction, there are two many variables.

 

Mark,

Here is the formula used to determine the answer to this question.

In the February 2002 issue of Car Craft, on page 54, under the "How to Port Cylinder Heads" article, they state that AirFlow Research has quantified the question of Air Flow = HP with a formula, which they claim is "fairly well established." It reads thusly:

hp = cfm x 0.2575 x number of cylinders.

So just plug in your numbers and it should be pretty close.

Let's use the stock L31 Vortec head as an example. Its maximum flow is supposed to be 226 cfm at .500 lift. (This is according to Destop Dyno 2000's flow file.)

Therefore we arrive at 226 x 0.2575 x 8 = 465.56 hp

Incidentally, the ported and polished 305 heads that F-Bird'88 was offering you for $375 support 465 hp, too.

So tell me, why are you spending twice that amount for the same results???

 

So suppose you have a complete engine, and install
the vortecs.. and then the ported 305's, the result
will be the same? what about their designe?
its not the same...
but still is adds up to the same thing.. buying the 305's
getting them proted.. labour..
Just my opinion..

 

oops, i meant the sportsmans

 

I'm getting the heads for $730, the Vortecs are $500 right? and $150-180 for the intake, that right there is $650 we'll say.

Now, add in changing the springs to fit my cam, and they don't have screw in studs with guide plates, right?

So, I think I'm making a good choice.

 

Flow numbers are good but they don't tell the whole story on a set of heads. Aftermarket castings are always better since they use different molds to cast the heads. The deck surfaces are thicker and they improve casting quality over production heads. Out of the box sportsmans may flow as much as the ported 305 heads but the sportsmans can then be ported to get even more flow without risking making the walls too thin.

The aftermarket castings will also have screw in studs, larger valves and larger spring pockets. The cost of converting a production head to match an aftermarket head starts to get close to or more than just buying an aftermarket head.

 

No, you are making an expensive choice!

F-Bird'88 offered you a set of heads that flow as well as Vortecs, and even better than the Sportsman IIs, but you are buying the latter.

He offered them to you for $375 plus shipping. And they also have the screw-in studs, larger springs, etc. Moreover, they are the regular bolt pattern, not Vortec style.

How can $730 heads be a better deal???

 

Stephen,

Let's look at that.

Are we building a dragster-only that is one's toy to try and make faster and faster? Are we looking for 12s, or 11s, or even 10s?

Then a set of aftermarket heads are the choice, if 11s or 10s are the quest.

But F-Bird'88's 305 heads are capable of supporting 490 hp on ANY smallblock Chevy!

That puts you into the 12s with ease, and even the 11s!

Let's apply the science of physics to this so we can make an INFORMED choice

Mark Shields is buying the Sportsman IIs, which support 450 hp as delivered, for $730 US.

So let's prove how much hp F-Bird'88's recently ported 305 heads can produce.

In the February 2002 issue of Car Craft, on page 54, under the "How to Port Cylinder Heads" article, they state that AirFlow Research has quantified the question of Air Flow = HP with a formula, which they claim is "fairly well established." It reads thusly:

hp = cfm x 0.2575 x number of cylinders.

So just plug in your numbers and it should be pretty close.

238 cfm x 0.2575 x 8 = 490.28 hp!!!!!

WOW!!!!!!!!!!!!!

That is well beyond any stock set of Vortecs or out of the box Sportsman IIs, and should put your 3rd gen well into the 12s--maybe even 11s with some weight reduction

And he was selling these heads a couple of weeks ago for a MERE $375 US, plus shipping!

You can duplicate what he has done by following the instructions laid out in the thread linked at the end of my sig, and only spend about what he is selling them for!

So who says you need to spend serious coin to have an excellent set of heads, eh???

 

Why the Dart heads?

If you're spending that much, go with the Pro Action Lightning Iron heads. They flow RIGHT WITH the AFR 195cc ( intake runner volume ) right out of the box!!!

Go HERE to see the 180cc Pro Action heads ( 64cc chamber size ).........look at the flow #'s......

These OUTFLOW the AFR 180cc street heads, and they are within a FEW cfm throughout the RPM range with the 195cc AFR heads.

Price?

Try $750 HERE

Just email or call to ask for the 180cc versions, are use the 200cc versions for the same price.

ANY way you cut it, the Pro Actions flow with OR outflow the AFR's.....period.

Several guys around here are using 'em.

My exhaust guy has a 408 in a '68 Camaro, hydraulic cam, single plane intake, 750 carb, headers etc......he was running low 12's with some hogged out Dart heads. He was talked into trying the 200cc Pro Action heads by a local guy......NO OTHER changes, the out of the box Pro Action's have his car running consistent 11.80's......


HTH

 

Ya have to take the theroretical potentail hp of a head based on peak intake port flow, with a grain of salt.

This hp *potential* is possible but only on a ideal motor,
with ideal induction, exhaust, carbs, cam timing combustion chamber, fuel etc.
It also makes no mention on the size of the motor or the port volume.

Our motors are not ideal. Some will be a little more IDEA than others.

For our purposes, if you can obtain 80%-90% of this
potential power rating, you've done a good job.

I would estimate a head like my ported 305's
to be good for about 415 to 435 hp (with supporting parts) on a 350 or 383.

The point is not wether these are the ultimate head (they aren't)
or if you can buy or make better heads (you can)
Just to illustrate what can be done with an old stock head and
a few extra buck and time.

Note: The actual flow numbers of a "out of the box" Sportsman head seem to vary quite a bit.
Depending on who did the machine work.
I've seen them flow from 224 to 240 out of the box.
The ones on the upper end of this usually have some minor
bowl work.
These heads are capable of over 300cfm @28 with full porting
and big valves. Dart says they are good for 650 hp when fully prepared.

 

EXACTLY!

These heads are PERFECT for anyone trying to get their car into the 12s--but doesn't have a boatload of cash to play with

Abd they are MORE than adequate for anyone wanting a very swift street cruiser

 

Hey, that sounds like me!!!! Better keep 'em.....

 

I agree, F-Bird'88!

COME ON EVERYBODY, A CAR THAT RUNS 12s OR 13s IS A MIGHTY FAST CAR!!!!

LET'S GIVE OUR COLLECTIVE HEADS A SHAKE AND WAKE UP HERE!!!

 

You guys don't make easy choices for me.

But , I do HOPEFULLY by next year to be running a SC, not sure if that matters, I'll check out the above heads.

But, I have one question about those 305 heads, I honestly, don't know what a good head is, I mean I have some smarts compared to a ***** or something, but compared to some of you I'm clueless.

So, why is it, that a few of you are pressing the issue of how great 305 heads are and others say get aftermarket heads.

I mean, those 305 heads are very appealing, because I could buy them, my headers and my DP carb right now, but I realize heads are an important part, so I feel like why not invest a little more in them now, rather than redoing it later.

 

oops, I thought you were talking about why not get Vortecs.


But those 305 heads are maxxed out flow wise right? or HP potential.

I am going to have the Sportsman IIs ported and polished too, and they should blow away those 305 heads I would think.

 

Mark: You seem to be all over the planet on what you want to achieve.

You want a supercharger but won't buy a simple set of valve springs to complete a cam swap.

If ya really want a nice supercharged street motor
then starting with a GM Goodwrench motor was the wrong choice.
(it won't last long)
Again if ya want to end up with a good superchargerer motor
then a set of ported 305 heads wouln't be the best choice either.
(ya want a reletively low compression motor under a street SC.)

A set of Dart Sportsmans would be a good basis for a blown street motor build up. (72 cc heads)
You want and need a stout short block ( 4bolt mains, forged crank, pistons etc) {detonation insurance} Not a Good Wrench motor.
You should have a good look at your wallet and set realistic goals
and head in that direction.
Other wise you'll just end up with a mismatched mess that will self distruct.
We all want a Wild Blown Street Beast.

Just how practical that is on a College budget is another thing.
You might want to take a course in Economics.
It all comes down to $'s and cents.

 

I already have.


I'm just working with what I got, little by little, unfortunately I can't buy heads and SC at same time. Or I would. I also wanted to stroke this block not this summer but next. My brother just said to get another block to do it too, sort of like you're saying.

Oh, and I did buy the springs, just didn't install them. I knew it wouldn't be long till I got new heads, so the trouble wouldn't have been worth. Just like you push those 305 heads from expericence, I've had many experienced people in my life say the stock springs would be fine.



I'm just going to take out a loan now, and get it done with.

 

Yeah, I would guess that there wouldn't be a whole lot more flow left in the old 305 castings. Sheesh, we have our nerve steering you to heads that only support 490 hp

Imagine the embarassment you'll suffer when people find out that you only paid $375 for them. They couldn't be producing socially acceptable hp unless they cost at least $750 :nono:

Listen Mark, your desires are growing exponentially! Last week you were simply wanting heads that could produce 400 hp on a 350. Prior to that a 350 hp 350 was the cat's meow--as long as it went rumpity-rump at idle. Now you want to super-charge your engine.

Dare I say that NO ONE can satisfy your cravings for THEORETICAL hp?

 

ALOT of good points made on this thread...and speaking as someone who's built a few pretty fast cars on a shoestring budget ( wife, kids, mortgage etc will do that...enjoy being a "poor" college student ) I think I can add something here...

As for the worked 305 heads, that's sounds like a great deal, but like others pointed out, it ALL DEPENDS on what your plans are down the road... if you're going to a SC, then bumping up the compression is NOT what you want.

And as far as the Goodwrench motor goes, I don't see any trouble using it with a SC, but you'll need to toss the cast pistons for some good forged or hyperutectic pistons if you want to have piece of mind....not to mention keeping pieces of piston from flying around

What's your goal? ET? High speed? HP for the sake of HP or what?

While SC's can be great power-adders, $ for $, with the money you spend to SC your engine the RIGHT way, there are other avenues to explore for the same power....you do realize you'll need to go to a bigger fuel pump right? And if you think traction is an issue now, wait until you try to hook with the 700's LOW 1st gear with the SC.....

I owned a 11 second '80 Malibu a few years back. ( 11.9X's BUT IT WAS an 11 second car :P

I learned ALOT about building a car in stages, and on a budget. Planning EACH upgrade to complement and ready the engine for the next upgrade is ALOT harder than just whipping out the visa or the checkbook.....

All said and done, when I sold the Malibu I had less than $4500 in the whole car ( including $900 purchase price ). Alot of people didn't believe me....but it was simple, I didn't have the extra $ to throw at it and hope it went faster...and it was my DAILY DRIVER to boot.

The base engine you have now is not a bad one at all. 4-bolt block, thicker casting ( believe it or not the Mexico cast blocks are thicker than some of their counterparts ) and can be made powerful with not alot of cash.

I threw out the Pro Action heads because it seemed to me your ARE planning on purchasing the Dart heads..IMHO the Dart's are more for people who plan on working them down the road.

The ported 305 heads sound like great bang for the $ , but I've never seen the flow numbers, and to be honest the 305 castings weren't the greatest, and have been know to crank and warp, but removing casting flash and cast in weaknesses can improve that I'm sure.

Figure out what your goal is for the car...

Other things besides the engine will come into play when you start putting 350-400 HP to the drivetrain. Is your tranny up to snuff for that abuse? Rear end? How's the rear suspension set up? All the power in the world means nothing if it won't hook.

There can be big differences in parts selection when you jump from wanting a 350 HP motor to 400 HP and above. Compromises will have to be made on driveability, gas mileage, durability etc.

The simplest rule of the thumb I learned is this......the more cubes you have to start with, the LESS you have to push the engine to reach your power goals.

Running 12's is possible with a 305, but that's running that 305 on the ragged edge ( not counting nitrous, that's another story, and it's expensive to keep filling that bottle, not to mention addictive......) Running 12's with a 350 isn't so bad.......running 12's with a 383 puts even less stress on the engine......and using a 400 makes is a milder, more enjoyable ( on the street ) package that still runs 12's......

EVERY component in an engine plays a key part in making power / torque ( HP is a product of torque anyway ). The biggest, highest flowing heads in the world don't mean jack if you're exhaust, cam , and tune isn't in the shape to support it.

If it were me? .......Hell I'm great at spending other people's money...

I'd get the engine you have NOW running to it's BEST potential. That means tuning, and more tuning. Finding out what's not right and getting it right. Maybe some rear suspension mods to get it to hook better...etc.

Then, when you've pretty much reached the end of the rope with that combo, upgrade it.....

Want some cheap power? Pull the engine, and blueprint and balance it. It's not voodoo......triple check EVERY clearance in the engine, and get them ALL as close as possible to the same specs.

Grind out the casting flash in the block, paint the lifter valley with Glyptol etc to improve oiling. Balance the rotating assembly won't gain you power per se, but it WILL make the engine rev faster, and keep it from straining it more in the process.

Search for used parts.....that's how I built my Malibu, and the IROC will see some used parts too...

The headers you have ( TES IIRC ) are fine for your combo. I know a guy now running mid 12's in a DAILY DRIVEN 80's Monte Carlo using the small primary Edelbrock headers......don't seem to be holding him up any.

I see NO trouble in being able to get 400-425 HP out of that Goodwrench motor with the right add-on's. Remember, it's compression ratio is probably as low as 8.2 : 1.......don't rely on what the GM specs say.

The 58cc 305 heads would help that, as well as a thinner headgasket........

It's all dependent on what YOU want, and how much time and $$$ you have to spend......


HTH

 

ctandc:

Nice post. Sounds like you been there and got a few Tshirts, to say the least. Lots of truth there.

Mark : Hope you're paying attention and not just planning your next 3000 posts.

Sittin' Bull: Your cheque's in da mail, Bud......

Good Luck to ya.

 

Yes I am.

But, I don't see why you guys seem surprised that I mentioned a SC. I mean, sure I've never mentioned it before, but it's not something I was able to get before, because obviously I had to get cam/heads/intake/carb/exhaust before I go slappin a SC on it. I'm not talking about running 20psi or anything, a nice 8 psi seems to be ok for now at least. Then I'll sell these new heads to get lower compression ones.

Maybe, I'll take my brother's advice and some of yours, and just build another motor. One built for a SC. Maybe I could talk my Dad into it as a father/son thing.

 

Yeah, now what was my cut? 60% for me and 40% for you? Sounds about right

Man, it is an awful hard sell to get people to keep their money and buy a wonderful set of heads for half the price, eh?

I guess we two Canadians will have go down to the lower 48 and burn down the White House again, just like we did in the War of 1812, simply to get their attention

It only takes a couple Canadians to thrash a whole boatload of Yanks, anyway

 

I just hope I made the right choice. Oh well, it's just money, I'll make more, I'll spend more.

 

Sitting Bull:

Don't think we need to go there. This is a friendly forum.

We all know who is da best eh.... #1

No problem if they don't sell, they'll make lovely lawn ornaments... lol

Or someone here is going to have one hell of a Street Stock next year. hee heee heee...