AFR 210, 220, and 227 -vs- CID
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From: overland park, ks usa
AFR 210, 220, and 227 -vs- CID
I was on the fense between the 210, 220, and 227 head. I've read a lot about runner volume and port velocity and the effects it has on street driven NA cars. However, I've not heard much discussion related to displacement of larger engines and the net effects of port velocity or the active filling (boost) -vs- passive filling (NA). I was under the impression (right or wrong) that when you went forced inducted, the traditional rules for runner size where pretty much nullified. Before I drop $2600 on a set of 227 LT4 Comp. heads, I hoped I could solicite more information regarding this matter. To start, I've tried to do a displacement-vs-port size comparison (see below) and the cancelling effects of each:
350 cid/8 cylinders=43.75 cid per cylinder
200 cc intake runner/43.75 cid = 4.57 cc per cubic inch or 4.6:1 ratio
383 cid/8 cylinders=47.87 cid per cylinder
220 cc intake runner/47.87 cid = 4.59 cc per cubic inch or 4.6:1 ratio
398 cid/8 cylinders=49.75 cid per cylinder
227 cc intake runner/49.75 cid = 4.56 cc per cubic inch or 4.6:1 ratio
I've not quantified the formulas above nor do I make an assumptions that they represent any type of "real world" anything...
In the examples above, wouldn't the theoretical port volicity be the same? If so, how can someone say a 227 cc head is too big for my application without knowing my displacement (amoung other factors)? Also, as blower cams tend to have less scaveging/overlap and therefore are less dependent upon intake charge inertia, wouldn't this serve to lessen the weight on the intake volume debate? Furthermore, what are the actually effects of positive pressure to the intake charge of a large ported head?
Thanks for letting me ramble on...ct
350 cid/8 cylinders=43.75 cid per cylinder
200 cc intake runner/43.75 cid = 4.57 cc per cubic inch or 4.6:1 ratio
383 cid/8 cylinders=47.87 cid per cylinder
220 cc intake runner/47.87 cid = 4.59 cc per cubic inch or 4.6:1 ratio
398 cid/8 cylinders=49.75 cid per cylinder
227 cc intake runner/49.75 cid = 4.56 cc per cubic inch or 4.6:1 ratio
I've not quantified the formulas above nor do I make an assumptions that they represent any type of "real world" anything...
In the examples above, wouldn't the theoretical port volicity be the same? If so, how can someone say a 227 cc head is too big for my application without knowing my displacement (amoung other factors)? Also, as blower cams tend to have less scaveging/overlap and therefore are less dependent upon intake charge inertia, wouldn't this serve to lessen the weight on the intake volume debate? Furthermore, what are the actually effects of positive pressure to the intake charge of a large ported head?
Thanks for letting me ramble on...ct
Last edited by brand-x; Apr 1, 2003 at 07:19 PM.
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That is a pretty dam good observation from my point on this whole subject.
First, I wouldn't even bother with the 100% CNC ported versions of the AFR heads on a engine with a blower, the $1900 70% versions are much better because that extra 10cfm isin't going to show you anything significant with a blower.
Now the port size will. A 227cc AFR on any engine 383 and up is my choice. The port size is the restiction here to the ultimate HP capability of the engine, not just the flow.
Think about the velocity question relative to size and flow too. Would a head with 10% more flow and volume have a lower velocity? probably not but it will have more HP potential because the mean velocity will occur at a higher RPM. The AFR 220 vs the 227 Race Ready heads flow 2% more in that 3% larger volume, but I would still bet that in a 6000+rpm blown engine a 227 will make more power because the port size is large enough for the HP level (800+hp on 12PSI) When you play with a blower it's not about port velocity it's about the restriction in the system, which in a high power blown small block is the runner size, to a point.
Also when you said that the cam choice on a blown engine is smaller with more LSA it can use the larger ports on the street. This has been a point of mine for a while here. Even NA cars benefit from this, you need head flow # to get HP, then to make it streetable you need small cam. Well if you want streetable HP head flow (which comes with volume) and cam selection will get you there.
The intake maifold on a blown setup plays almost no effect on the engine vs when it's NA. It does play some, but a 800hp Blown 383 LT1 will only gain a small percentage with a good intake vs a 500hp 383 NA LT1. The blown engine needs a intake that is not too small also just like the heads and the flow doesn't really mean anything. (almost, again)
Now on a high VE NA application (100+)you are using the intake to add intake tuning pressure to the engine. You can easily see a postitive 6PSI @ HP peak in a well put together package. So in essence it works EXACTLY like a blower. THIS IS WHY I LIKE SMALL CAMS AND BIG PORTS, WITH A REALLY GOOD INTAKE. More TQ and more HP with a driveable engine.
I would go more with a 4.7:1 ratio and use less cam. But that is saying you are concerned with the 2500-6500 power band NA, once you add boost, juice or RPM that 4.7:1 ratio number is WAY too low.
Good question, it has alot to do with engine building as a package or engine design, which is how engines should be done. Everything has something to do with everything else.
Bret
First, I wouldn't even bother with the 100% CNC ported versions of the AFR heads on a engine with a blower, the $1900 70% versions are much better because that extra 10cfm isin't going to show you anything significant with a blower.
Now the port size will. A 227cc AFR on any engine 383 and up is my choice. The port size is the restiction here to the ultimate HP capability of the engine, not just the flow.
Think about the velocity question relative to size and flow too. Would a head with 10% more flow and volume have a lower velocity? probably not but it will have more HP potential because the mean velocity will occur at a higher RPM. The AFR 220 vs the 227 Race Ready heads flow 2% more in that 3% larger volume, but I would still bet that in a 6000+rpm blown engine a 227 will make more power because the port size is large enough for the HP level (800+hp on 12PSI) When you play with a blower it's not about port velocity it's about the restriction in the system, which in a high power blown small block is the runner size, to a point.
Also when you said that the cam choice on a blown engine is smaller with more LSA it can use the larger ports on the street. This has been a point of mine for a while here. Even NA cars benefit from this, you need head flow # to get HP, then to make it streetable you need small cam. Well if you want streetable HP head flow (which comes with volume) and cam selection will get you there.
The intake maifold on a blown setup plays almost no effect on the engine vs when it's NA. It does play some, but a 800hp Blown 383 LT1 will only gain a small percentage with a good intake vs a 500hp 383 NA LT1. The blown engine needs a intake that is not too small also just like the heads and the flow doesn't really mean anything. (almost, again)
Now on a high VE NA application (100+)you are using the intake to add intake tuning pressure to the engine. You can easily see a postitive 6PSI @ HP peak in a well put together package. So in essence it works EXACTLY like a blower. THIS IS WHY I LIKE SMALL CAMS AND BIG PORTS, WITH A REALLY GOOD INTAKE. More TQ and more HP with a driveable engine.
I would go more with a 4.7:1 ratio and use less cam. But that is saying you are concerned with the 2500-6500 power band NA, once you add boost, juice or RPM that 4.7:1 ratio number is WAY too low.
Good question, it has alot to do with engine building as a package or engine design, which is how engines should be done. Everything has something to do with everything else.
Bret
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Joined: Nov 2001
Posts: 36
From: Neptune, NJ
Originally posted by SStrokerAce
Now on a high VE NA application (100+)you are using the intake to add intake tuning pressure to the engine. You can easily see a postitive 6PSI @ HP peak in a well put together package. So in essence it works EXACTLY like a blower. THIS IS WHY I LIKE SMALL CAMS AND BIG PORTS, WITH A REALLY GOOD INTAKE. More TQ and more HP with a driveable engine.
I would go more with a 4.7:1 ratio and use less cam. But that is saying you are concerned with the 2500-6500 power band NA, once you add boost, juice or RPM that 4.7:1 ratio number is WAY too low.
Now on a high VE NA application (100+)you are using the intake to add intake tuning pressure to the engine. You can easily see a postitive 6PSI @ HP peak in a well put together package. So in essence it works EXACTLY like a blower. THIS IS WHY I LIKE SMALL CAMS AND BIG PORTS, WITH A REALLY GOOD INTAKE. More TQ and more HP with a driveable engine.
I would go more with a 4.7:1 ratio and use less cam. But that is saying you are concerned with the 2500-6500 power band NA, once you add boost, juice or RPM that 4.7:1 ratio number is WAY too low.
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Posts: 6,518
The mini ram? Give me a pick of that. It's not going to happen with a LT1 style intake, you need bigger (area) and longer runners. That Accel one might do it.
With a single plane conversion and the right cam, 530ft lbs with those heads should get you really close to that goal. I've done it with 20 less cubes, and 1 point more compression.
84 ft lbs per L doesn't just happen, a ZO6 has only 70 per/L, a M3 has the most (for production) at 83 per/L, 88-100 takes ALOT of work. So that ground between 80-88 is still not easy, but something a guy can do. It took me $15K to get 88+lbs ft per L, but you can get 82-84 with the right intake/heads/cam combo.
Bret
With a single plane conversion and the right cam, 530ft lbs with those heads should get you really close to that goal. I've done it with 20 less cubes, and 1 point more compression.
84 ft lbs per L doesn't just happen, a ZO6 has only 70 per/L, a M3 has the most (for production) at 83 per/L, 88-100 takes ALOT of work. So that ground between 80-88 is still not easy, but something a guy can do. It took me $15K to get 88+lbs ft per L, but you can get 82-84 with the right intake/heads/cam combo.
Bret
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Joined: Oct 2001
Posts: 144
From: overland park, ks usa
Originally posted by twells
brand-x, where in o.p. are you from
i'm at 127th and pflumm. lemme know if you wanna meet up sometime. i'd love to talk heads with you, as i have tons of questions of my own
thomas wells
brand-x, where in o.p. are you from
i'm at 127th and pflumm. lemme know if you wanna meet up sometime. i'd love to talk heads with you, as i have tons of questions of my own
thomas wells
I live at 127th and Metcalf...just a few miles down the road from you. Do you post on any of the local boards? If you do, I can be found at www.kcsr.org and I post under the names of 4wheeldrive and brand-x. I tend to run with the Performance by Design, MC Racing, and Procharger guys in Kansas City.When you get on kcsr, drop me an IM and maybe we can meet up at the dyno or something.
Chris
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Joined: Oct 2001
Posts: 144
From: overland park, ks usa
SSstrokerAce
I went with the race ported AFR 220cc heads. I started reading up on Jesel and I wasn't completely sure my shaft mounts would work on a non-standard head (i.e., 60-40 split valve placement). however, i really appreciate your insight into this matter. I agree with everything you said--mostly, I'm glad to know I'm not the only one that thinks this way.
CT
I went with the race ported AFR 220cc heads. I started reading up on Jesel and I wasn't completely sure my shaft mounts would work on a non-standard head (i.e., 60-40 split valve placement). however, i really appreciate your insight into this matter. I agree with everything you said--mostly, I'm glad to know I'm not the only one that thinks this way.
CT
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