OK, Daggumit, y'all have forced me to pull out the old Car Craft back issues. In the October '99 issue, they did a test called "Big Heads for the Street". Sound applicable? I thought you might agree.

In the test, they tried:

GM 492 heads (157 cc double humps flowing 215i/138e)
Dart Iron Eagle 180 (213i/172e)
Dart Iron Eagle 215 (252i/175e)
Ported Dart Iron Eagle 215 (221 cc flowing 286i/195e)

All testing was done on a 10/1 350 with an Extreme 274 cam (230/236).

Peak hp and torque were:
492's: 397 hp at 5,800 rpm and 386 ftlb at 4,800 rpm.
180's: 407 hp at 5,500 rpm and 400 ftlb at 4,800 rpm.
215's: 436 hp at 6,000 rpm and 411 ftlb at 5,200 rpm.
221's: 462 hp at 6,100 rpm and 421 ftlb at 5,100 rpm.

Now for the kicker. Average torque from 3,000 - 4,500 was also tested:
492's: 368 ftlb
180's: 379 ftlb
215's: 373 ftlb
221's: 373 ftlb

So, the best small head produced 6 ftlb more than the big heads at 3,000 - 4,500, but sacrificed 55 hp on top. Give me the 55 hp because you'll never notice a loss of 6 ftlb. Your cam choice will probably give up 20+ ftlb down low, anyway.


And about the old Cleveland (the Boss 302 in particular). . . That motor is basically a big block 302. I once read an article about how Ford replaced the Boss 302's 2.25" (!!!) intake valves with 2.19" (!!) because customers were complaining about soggy low-end. However, we're talking about a 350 using a 2.08" intake valve, which is far more reasonable than a 302 with a 2.25" valve.

And in my own experience, drivability differences between my 8.4/1 360 with 210's and my 11.3/1 383 with 210's were nearly indistinguishable and probably due to the compression ratio more than the port volume to cid ratio.

Mike

 

I have that artical too and have thought the same thoughts. The only thing that it doesn't tell you is how part throttle is. If you are going to put these heads on a engine that has 3.73s and a 3600 stall, then you probably won't notice much, but put these heads on a engine with stock gears and stall and you will be complaining all day. Personally I want a enigne that I have to shift no later then ~6300rpms. My main point is are you spending most of your time on the street or track? Do you really want to deal with a 3600+ stall light to light?

Power numbers tell you almost nothing about how the engine will act in tracffic. This is noticed in the 400hp 318 that CC did lately. They put a 750 Holley on a 318. Now that engine made stupid power for a 318, but that thing will suck driving down the road without throwing gear and stall at it.

 

For the most part larger volume runner heads are not going to make an engine "lazy" down low, unless someone did some bad port work and destroyed the low lift #'s. The camshaft is the major determining factor in part throttle response.
I'm running ported factory LT1 castings with 1.94/1.50 valves and an intake runner volume of 177cc. I've put down 450rwhp yet have had LT1's with much larger castings jump me out the hole regularly, yet I'll walk by them on the top end easily. That's the total opposite of the traditional thinking.
Personally my choice on AFR heads is the 220. Excellent head!!! I've flowed these heads & have seen dyno & track times for a few cars equipped with them... impressive.
Steve...

 

i daily drove with a 3800 stall and didnt have any complaints.part throttle was just fine.

why would anyone even think about running a great head with stock cam and stall?
half of your argument has semi-valid points,then you go and make the statement about stock convertor and gears.

 

have you seen anyone with those heads on a 350???

 

If you want to make power to go fast you need to put the biggest head on that thing as you can. It has been proven many times that the fast guys all use huge heads. One example is a friend of mine has a 355 with AFR 227s on it. The car runs 10.doh's all day long with full raceweight. (and a pro-shifted 5spd)
The most important thing is to have a cam that utilizes the airflow of the heads you use.

 

Of course a car with that bid of a stall isn't going to have prt throttle complains bcuz when you give it any kind of gas the engine rpms will jump to where they need to be. My point about the stock conv and gears was for comparision reasons. How many people do heads and cam at the same time? Usually it is one follow by the other at a later date. Talk to xxsaintx(sp?). He put a cc306 on stock heads and gears. He said that it had great topend, but getting it off the line at the track was a trick, and I'm sure that driving it on the street was the same. Those heads are for 3000+ rpms. Put that with a cam behind stock gears and/or stall, and it will be interesting to drive on the street.

Joe, who are you talking about?

 

I don't know why you keep bringing stock stuff up. When someone is interested in swapping heads, that's a pretty good indicator that stock isn't cutting it. Remember, building a motor is a systems approach. Running a huge cam with stock heads can work, but it certainly won't be optimized.

You're also wrong about the 210 heads being "3000+ rpm heads". The torque numbers I gave earlier were from a direct comparison vs. mildly ported stockers. The 210s showed a torque advantage starting at only 2000 rpms! And the advantage continued all the way up the chart...

 

i us them on a 355 ,i also ported them a little bigger,my combs on the radical side.it made 465 rwhp with a junk clutch and a flowmaster catback

 

Do what every you want to do. Until I ride in a car and drive one with such a radical setup, I still be hard headed about this. I would love to be proven wrong, but I still don't see port velocity, which is very important on the street, being very good with those heads. I still say it will take some rpms to make your power. I'm not really a person that likes to have to turn the engine to 7000rpms to shift. Of course, I have always like bb trq too.

If you do go ahead with this, let us know how it goes. Should make some insane #s. BTW if you are looking to spend that much, you should look at TEA ported AFR 190s. They end up at about 207cc, flow 295 cfm at .6, and are about $2500, from someone I talked to. I would like to do this, but thought that the head was a little too big for a 350.

 

you are kinda of right it takes a little rpm to make power.depends on your idea of hi mine was around 6500.i hope with a new clutch and differnet exhaust there another 100 hp in there (the clutch was smoken when we pulled it exhaut is a 3 incatback)i also went lite rotate assembly.i hope its 630-650 fhp we will see.

 

Kind of interested in what your dyno looks like. Do you have it, or was that with the bad clutch?

 

Hard headed is another term for ignorant you know.

They gave given you fact after fact, and all you keep repeating is. "I heard" Open your mind to new info, cause what "you heard" before, isnt correct.

 

You all make my head hurt

I havent run a 210cc+ head on a stock bottom end and most people haven't, so only a few that actually have can give ACURATE information on how part throttle condition is. Everything else is heresay and speculation.

FWIW I am going to be running a 215-220cc (non LT1 head and after porting) on my stock bottom end LT1. I think its all in the combo..... gears/cam/tuning/etc to make it work fine on the street.

 

OK, I know this thread started asking about AFR's, but it's turned into a general discussion on big heads on the stock bottom end. Mine aren't AFR's, but they are big port heads nonetheless. My Brodix -10's have 2.08 intake valves and flow 302 cfm at .500 lift. I was warned when putting it together that I would lose all my bottom end. I lost a little, but it screams higher up. Part throttle is really pretty good, definitely better than I was led to believe. I can cruise 6th at 60 mph (4.11 gears) and up very well. If I want to accelerate hard, I need to be at 2000 or higher. I've never really had a concern with part throttle operation at all. It is just fine. This is the car I drive to work, so it's not a strip-only car, and I like the driveability.