Which head is going to perform better on say a 355 or 383 as far as velocity?(<--spelling)

I was comparing the afr 195's to the Dart Iron eagle platinums.

AFR 195's
Lift Intake Exhaust
.400 240 178
.500 260 190
.600 262 194

Dart 200 Iron Eagle Platinum's
lift Intake Exhaust
.400 242 198
.500 272 208
.600 283 214

I know im comparing different runner size and one is aluminun and the other iron. But how much will the different runner size affect velocity on a 355 or 383.

 

anyone??

 

The runner sizes (195 vs 200 cc, right?) is a wash because they are so close to each other. Assuming you will have a cam/rocker combination that has 0.500" peak lift at the valve, or less, then the flow numbers above 0.500 are irrelevant because your valve lift will never go there and the pressure differential available once the valve is at peak lift doesn't buy you as much cylinder filling as you might think. That statement might still be true even if you ran a cam with 0.550" peak lift.

The flow values are the same on the intake side at 0.400" lift but the Dart is better on the exhaust by a lot. So based on that info alone, I would say the Dart wins because it will clear the cylinder better. You might also compare the flow-vs-lift for each from .050" to 0.400" to see if the trend is the same (i.e. that the Dart is slightly better than the AFR).

Then there is the matter of cost for each head, especially for heads that are already populated with valves + springs/retainers/locks. My guess is that the iron Darts are still less $$$ than the AFR. I also can't predict what gain you might have if each of these heads were ported and then re-flowed. I think both heads work etremely well after porting, based on what's shown in Vizard's cylinder head book. So it may boil down to how much do you really want to spend and can you stomach having a front end that weighs 50 lbs more if you go with the iron Dart. FWIW.

 

I was very impressed with the flow numbers I found on the darts. I can get them for under $900 with springs that match my cam. I will be out about $1300 for the afr's. I just dont know if it is worth the extra $400 just to go to aluminum. The cam I will be using will have .550 lift if not more, so I will take the .500 flow numbers into consideration also.

I guess it would have been different if I was comparing 195's say to 215's or 230's.

 

where did you find those flow #'s? those are pretty sweet numbers. i was considering AFR's but those numbers look tempting.

 

found some here

http://users.erols.com/srweiss/tablehdc.htm#Chevy

 

That is the same site. It says that they got the numbers from Darts own site.

 

I can tell you first hand Dart over rates their heads BIG TIME, I've been through my machines shops catalog of all the heads they've flowed over the years with the same Super Flow 600 and Dart heads are on average 30cfm OVERRATED in both iron eagle and Pro 1 series.

For example, a close bud I race with had his Dart Pro 1 230's flowed after EXTENSIVE port/polish work and those heads only flowed 260cfm at .700 Where as AFR is noted for listing factual flow numbers and that was backed up when I had mine flowed, I took in my AFR catalog the day I picked up my heads and compared them to what the shop came up with and they only varied 3 cfm at most and still outflowed the Dart 230's that had alot of work dont to them.

You'll make more power with the AFR's since they truely/actually/literally flow better than the iron eagles and you'll also make better use of the power since you'll be alot lighter in the front end.

 

Thanks for the info. I thought that dart's numbers were fairly close to what they advertise, but oh well.

Im just looking to build a good 355 to run say 12.50's in the 1/4. I could probably do that with vortecs and a good cam.

 

Vizard has a fairly large section on the Dart 2 iron heads in his sbc head porting book. IIRC he does show one set of stock flow numbers and then two different sets of ported flow numbers. Ported was obviously improved over stock especially on the exhaust.

After rereading those numbers last night, I'd say that unless Dart revised their casting a lot in the last 10+ years since Vizard's book was written, then I'd believe IHI's comment that Dart exaggerates the numbers and AFR doesn't. I've never heard anyone say anything negative about AFR heads except for the cost. I can't say the same about the Dart heads.

That said, I'll add that you MIGHT find other, independent, flow numbers on the Dart heads on other boards or on the web if you search. Did CHP or GMHTP (or other) ever test the Dart heads in their head-flow series?

 

If I recall, I beleive they did do flow test. I will have to do somemore research and see what I can find. I might even have an artical at home.

 

Main article with clickable links:
http://www.chevyhiperformance.com/techarticles/41598/

200+ cc intake ports for sbc:
http://www.chevyhiperformance.com/te...98/index6.html

The caveat is whether CHP got the heads directly from any of their vendors (possible ringers) or got them from a supplier (out of a batch of heads, so no ringers). It looks like the Dart flow #s depend on which head you choose. The AFR heads all look terrific out of the box.

See if GMHTP has any flow numbers.

 

There have been some revisions to the heads over the years and Vizards numbers are at 25" instead of the "standard" 28". So you'll have to convert those numbers for comparison.

IHI,

I also believe that the published Dart numbers are high on their box stock stuff. However, extensively ported Darts only flowing 260cfm,,, it's obvious who ever ported them did a terrible job. I've got a set of Dart 220s flowing within 6cfm of that on the exhaust.

 

Regardless, even box stock they should flow over 260cfm....as that 230 is the larger of the Pro-1 stabdard 23* sbc head...ported/box stock....still a very poor performer.

 

I finally got my 195 afr's. while a very nice head, I wished i dropped a couple hundred more and got the 220's.I would have had to wait longer... I just dont want to port them, very parinoid of over doing it. How much are people porting the 195's for a blower? much more on the exhaust side

 

Have them flowed first to see where you're at. A number of locals have had issues with AFR's not flowing as advertised either.

I know one was so far off that he actually managed to convince AFR to port his heads for him to get the flow numbers that were advertised. Turned out after that he got the flow numbers that he was looking for but for a couple of years had oil control issues, which he later found that in a few places the ports were cut paper thin and were actually sucking oil out of the lifter valley under high vacuum conditions.

 

Looks like I may be picking up a set of slightly used afr 190's.

I may drop them on my carbed L98 with a good comp hyd roller cam and rr rockers and see what happens.

I will probably end up building a 383 later on, so I will port the afrs when the time comes.