LS1-450

iTrader: (33)

Will be building a 383 out of our LS6 short block during the Winter months. Which of these two heads will move the most air into the combustion chamber, AFR 205's or ported 243's? Each head will have the swirl wing added to the intake valve bowl. Am thinking that the larger 210 volume runners on the 243's might be a better choice for a 383. However, the 205's have the advantage of a better overall airflow design.

So, is the 205 runner volume going to cause a greater restriction than the flow characteristics of a ported 243? A/F mix delivery through a carb & a single plane manifold; RAM air fed.

redtan

iTrader: (5)

Depends really who ports the 243s.

If it's a well known vendor like AI, TEA, WCCH, FRH etc. then IMO those would be pretty even as far as total airflow. Obviously the smaller runners of the AFRs will have more velocity and drive slightly differently, but as far as pure airflow they are about the same.

If it's some random guy with a dremel that's porting your 243s then I would opt for the AFRs.

Rise of the Phoenix

iTrader: (27)

I agree that it depends on who's working over the 243's. Do you currently have a set of the AFR or the 243 heads? If so, that may help may your decision easier.

svede1212

iTrader: (3)

FWIW ported 243s are going have 220-230 cc runners. AFR 215s would be a better choice and I will soon find out how the Mamo 220s will performer on my stroker. From my last two builds I'll say that spending money on the valve train with light weight valves, thicker rods and better lifters is important if you want more reliable high RPM and more power.

Tuskyz28

What would be the price difference between the pair of heads?

Rise of the Phoenix

iTrader: (27)

That question really can't be answered until we know if he's planning buying new AFR heads, if he already had 243 castings, and who would be doing the port work.

DavidBoren

If he is planning on buying new heads, then the afr205 is not an option, as the 205's haven't been produced in five years.

But, the longer stroke is going to increase piston acceleration away from top dead center. This increase in acceleration will be better complimented by higher port velocity of smaller intake runners.

Overall airflow is not the only consideration. The increase in displacement demands more air, but the increase in stroke/piston speed requires that air to be moving as quickly as possible.

I don't think there is any comparison between which would be better. AFR has made one hell of a reputation flowing volumes of air through relatively small runners, and I believe it to be the superior head for a stroker motor.

Rise of the Phoenix

iTrader: (27)

If the OP doesn't have the AFR heads, then you are right, unless you find a used set, they don't produce them anymore. Why not go with the AFR 215cc heads? Those would work quite well on the 383. Or possibly the AFR 230cc heads.

NAVYBLUE210

AFR 215s, & 230s designed for 4.00" Bore Minimum.
AFR210 is the current head for the 3.90" Bore, the
MMS 220s with lighter valves and LLSR would be best for
7000+ RPM on a 383", no comparison to any factory ported
Head.

96capricemgr

iTrader: (1)

You understand heads are more important than displacement?

Sounds to me like you have put the horse before the cart.

Well ported heads on a stock shortblock will outperform as cast heads on a stroker, and ignore anything the guy tell you you need small heads for a stroker has to say. He has read too many books, cherry picking what he wants to hear and can't see what happens in reality.

If you want to do a stroker a set of properly ported 243s with a trunion upgrade would let you keep stock rockers and costs reasonable and make more power than is practical to actually use on the street.

LS1-450

iTrader: (33)

I have tested & measured the benefits of valvetrain stability & RAM air through EFI live tuning software for years prior to using the carb. If we did not already have the heads, probably would not have asked @ all. Our LS1 shortblock currently using the AFR 205's @ 12:1 SCR, 8.4 DCR, made 548 BHP, ran it up to 7K, all the valvetrain mods, ARP bolts & studs, moderate cam, long tubes...etc.. Am quite familiar w/ building power from stock dimensioned short blocks. It's the stroker that's new. Some may have seen my thread about a month ago asking for help understanding strokers.

Am sure there are better options, but, heads will be either the 205's or 243's. From what has been posted, will probably just freshen up the 205's. Will be using our LS6 block for the stroker & pull the AFR's off of the LS1.

Rise of the Phoenix

iTrader: (27)

Have you checked these threads out OP?

https://ls1tech.com/forums/dynamomet...afr-205-a.html

https://ls1tech.com/forums/dynamomet...-included.html

96capricemgr

iTrader: (1)

If you have the AFRs send them for porting. Porting will gain you more than the stroker crank. Displacement needs airflow to make power.

nobreaks254

iTrader: (50)

im sure properly ported 243's will move more air but will lack the low end and response of the 205's. I ran 205's on my 383 with a 238/240 cam with 11.5 compression and it was a beast. Great torque as low as 2000 rpm and spun up to 7200

LS1-450

iTrader: (33)

Thanks guys. This is the kind of info. I was looking for. It's just a starting point. When I first completed the Munster in 2003, it had a stock LS1 engine. It now has available to it any of 3 different LS based assemblies. So, even though am starting w/ less than ideal heads, everything will improve & advance over time as I learn more about strokers.

DavidBoren

No need to make me look like an @sshole, man. I already do a good enough job of that on my own.

I never once said you need small heads on a stroker. I said the added intake velocity would be more beneficial on a stroker motor due to the increase in acceleration away from top dead center.

Obviously the heads need to be large enough to move adequate air volume to support whatever displacement the engine may have. That goes without saying. Moving that volume through the smallest intake runners as possible will increase the velocity, in juxtaposition to heads flowing the same volume through larger runners.

Both heads in question, the afr205's and ported 243's, are going to end up flowing ~300cfm, which is enough to let a 383 breath until about 7k. But the afr's are using smaller intake runners, meaning the afr's have more velocity and are more efficient.

And what part of any of that only applies to textbooks and not reality?

Exidous

iTrader: (11)

If the 205's are in stock form I'd say have them touched up around the seats for uniformity and rock the hell out of them over ANY ported factory small bore casting. The car will feel awesome down low and properly cammed will carry to 7k all day long. Whereas a ported 243 will feel equally awesome up top but the low end may leave you wanting. Plus the extra velocity will help mix the A/F mixture out of the carb.

kinglt-1

iTrader: (26)

The low end feels great with my tea 243's(11.4:1)...with the converter locked around 1400rpm I can step on the throttle and the car just pulls. a 383 on a similar setup I would expect nothing short of stump pulling tq.

edwardzracing

iTrader: (59)

Also love my TEA 243's. I loved them even more after reading this article:

The Ultimate Chevrolet LS Cylinder Head Test - Speed Parts Testing

It is a bit dated, but I loved how well the TEA 243's did against the competition... and when you compare the price tag... it simply makes good sense. Add me to the list of guys voting 243's with a good CNC porting.

KCS

iTrader: (20)

On the other hand, air needs displacement to flow.