Just wondering, Ihave heardmuch on this matter.
for example ,if you have a set of190ccheads on a car with a good twin setup and a ton of boost, you really would not need to get say a 220 cylinder head, seems kind of the opposite of an NA motor where for more power, a bigger cylinder head is a must, so, just how important is the actuall size of the cylinder heads to make big power on a turbo setup?assuming both the 190cc and 220cc heads are equally as slick and flow great for thier respective clylinder head sizes?

 

With the 220cc heads you will be capable of making the same horsepower with less boost as you will be flowing the same amount of air at a lower pressure (more efficiently)... with the 190cc heads, as long as you stay in the efficiency range of the turbo, upping the boost can create the same air flow as the lower boosted 220cc heads. if you're after all out horsepower and have the dough to build a beefy enough bottom end and to create a stable fuel system, and get turbo(s) to match the power you're after, you can ultimately make more power with the 220cc heads because they create less of an intake restriction and the higher the boost the more efficient the the system works as a whole.

that should just about explain it..lol

Chris
Next Generation Motorsports, LLC

 

Is there a point where the 220cc heads would affect driveability? For instance in a turbocharged car that is mainly street driven, would it be better to use the 195cc or the 220cc?

 

No.

It is a pet peeve of mine that people spread this mis-information. In the grand scheme of things, a 220 head on a 350 cid motor isn't that big.

I had an 8.4/1 compression 350 with 210 cc heads and driveability was fine.

Mike

 

Mike is correct, the 220cc head is not too large for a 350 CID motor, I think you'll find that the camshaft has more of a driveability role in the motor combination. a smaller port volume on cylinder heads will however contribute to the torque curve being higher in the RPM range as the port velocity is lower until the engine is moving enough air to make use of the larger port volume and make it efficient. this will be more apparant with a larger camshaft with more overlap. with the camshaft you have in your sig, you should not have any driveability issues save for a nice lope at idle, and a much broader torque curve through the RPM range.

Forced induction motors see less of a driveability issue as the port velocity is "assisted" by the charged air system (TC or SC). ie...as the valve opens air is not relying on atmospheric pressure to fill the cylinders.

larger cubic inch motors will see the torque curve come in earlier as the displacement opens a larger void faster as the piston drops on the intake stroke and the amount of air trying to fill the cylinder will be greater, with a higher velocity of air movement through the intake port. this given the comparison of the same size heads on the two different CID engines.

So to most, the driveability issue is not necessarily that the engine does not drive well, but it will lose some of its lower RPM torque in swap for a stronger mid and high RPM curve. an example is the difference between the L98 TPI and the LT1, the L98 had fantastic low RPM port velocity attributed to the 17"s of intake track length and smaller ports, but was unable to supply the engine with enough air at higher RPM to maintain an increase in power. so the L98's torque curve in most cases if viewed on a dyno chart started very high very early on in the RPM range (almost off idle). the LT1 made similar torque numbers but due to its lack of low RPM port velocity, it was created higher in the RPM range. if you have driven both cars around town... you might make the assumption that the L98 was the faster of the two cars when in fact the LT1 was. it is all in the perception of acceleration which is always highest at the torque peak. and you likely felt the torque peak more often in the L98, then the LT1 unless you drive around above 3k RPM. to counter this lower torque early on, most people install higher stall converters and gears or transmissions with a higher ration gear set. ok writing a book again..

in the end perception of driveability is greatly skewed between car owners..... to soem a dragster is a very streetable car.. for others if it doesn't drive like a Cadillac, it is not streetable.. just have to decide which side of the spectrum you fall under.

hope this helps!

Chris

 

Order of importance to driveability:

1. Camshaft
2. Torque converter
3. Engine size
4. Compression ratio
5. Intake manifold design
6. Intake port volume

 

Thanks for the information guys. I am planning on building a forged 383 with AFR heads (74cc chambers) that will be either turbocharged or supercharged+N20. And I was wondering which size of AFR heads to get the 195, 210, or 220. I guess it just comes down to what my budget can afford as they all will work.

 

I'd get the 220's. I'm using 210's on my supercharged 383, but wish I would have gone bigger.

The 210's/220's flow far more than the 195's. We've flowed a couple sets of 190's/195's and found 230 - 240 cfm peak.

The 210's/220's flow 280 - 285 cfm.

Mike

 

Excellent, that's the information I was looking for!!!

Thanks Mike.

 

I'd get the best flowing heads possible.

I have an LS1/LS6 setup, but my 6.0's flow 300/220 and I would not lose power going to a set of heads that flowed 315/230.

 

Johny boy, just gimmie the hit and Ill land on you this summer...........what do you say?

 

Strap on a pair and then sit DOWN.

Seriously Langmaneedesiotios, I'd get the best heads I could afford since the blower or turbo can use it. Just run enough cam.

 

Im running the afr 220's on my car. They flowed 304/238, which I thought was pretty impressive for an out of the box afr. If you go turbo you should not have any driveablity problems with the camshaft. I had an all out "race track only" cam in the car last year, and thr car drove just fine and pulled plenty of vacumm; although the lifters needed replacement quiet frequently. I changed to a smaller cam because it's my daily driver in the summer.
You drivablity problems will probably come to play with the computer you decide to use. If you plan on doing this motor pick yourself up a FAST computer.

 

The better heads make the PUMP more efficient. If I could run 350/240cfm heads I'd be all over it.

(Jake tell Jess that $$$ is on the way for the parts thanks for the hookup)

 

tell me if you guys think this will work well. AFR 210's with a 224/236 114lsa, 383 lt1 with a d1sc 15# is that to much head for what to do, i was planing on going with the 195s but after reading all this im not sure what i want to do. i plan to do all this with the stock PCM and the Impedence converter for the injectors. IS THIS REALITY WITH THE STOCK ECM REPROGRAMED.