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Discussion Starter · #1 ·
What is the amount of flow than i need to rev one 306 at 7800 rpm .
What is the the X factor to consider.
How calculate the flow requirement for this engine?
I believe the afr 205 is one good choise, but my friend talk the afr 165 comp pack heads is best. (it's only a 306 hes talk)
afr 205 and afr 165 comp pack have veri distinctive flow, what is the best choise?


<font size=-1>[ This Message was edited by: hotmaverick302 on 2/21/06 11:03pm ]</font>
 

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7800rpm and making power will need the 205's or similar (185's may be a compromise). the 165's will fall short probably 6000-6400 +/-. Just my 2 cents.
 

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Are you looking to make peak power at 7800rpm, or around 6500-7000 with useable power all the way to 7800? I'd say go with the 185's... I've got World Products Windsor Jr's on my 289, very mild porting done, and it makes good power all the way to 7500, and they don't even flow as much as standard AFR 165's, so I don't see why you would need to go as big as 205s.
Oh and as far as a 'formula' for calculating how much airflow you need, there isn't really one... but I've heard as a general guideline if you double the intake port airflow, that's the max amount of hp you should really use the head for. So an AFR 165 that flows around 225cfm can be used for up to 450hp. Like I said though this is just a really basic guideline, and not a rule.

_________________
'86 Bronco fullsize, 460, E4OD
'85 Ranger, 340hp 289, T5


<font size=-1>[ This Message was edited by: Motorhead on 2/21/06 11:26pm ]</font>
 

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Discussion Starter · #6 ·
WINDSOR Jr. FLOW NUMBERS: @ 28" H20 Unmodified:
.600" Lift: INT: 216 cfm / EXH: 141 cfm
.500" Lift: INT: 204 cfm / EXH: 135 cfm
If AFR 165 comp pack flow more it's a best than that and go make more power and reliabiliti? Afr flow 254/215 at .600.
 

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Yes I'd say go with either the AFR comp 165s or 185s. They will probably both make very close to the same amount of power... the 165s having a little more below 4500rpm and the 185s having a little more above. If you are set on AFR heads probably the best thing you can do is email AFR with your complete engine combo and intended use of the vehicle and they will be able to tell you what head will suit your needs best.

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'86 Bronco fullsize, 460, E4OD
'85 Ranger, 340hp 289, T5


<font size=-1>[ This Message was edited by: Motorhead on 2/22/06 3:36am ]</font>
 

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Depends more on the use of the car and the goals you have for it. I'll assume you have a vehicle/racecar that can take advantage of a high rpm small cube motor.

Total Engine Airflow (who ported a set of heads for a Ford Muscle build) built a naturally aspirated 306 that dynoed at just over 600 hp with a set of their 205 tfs heads. This was also with a carb I think. If you go to their web site you'll be able to find the article. I think that peak power was made at around 7,500 rpm. With well chosen parts the 205 AFR will kill the 165 and 185 in the rpm range you're talking about.

The Jeggs Kaase (sp?) heads made over 500 hp at the rpm you've described with a low comp junk yard 302, solid cam, victor jr, and a carb. Those heads are substantially bigger than the 205's.

You could make a stock head rev to 7800 on a 306. How much power do you want to leave on the table? Do you really care about torque under 4500 rpm with a motor like this?
 

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On 2006-02-21 08:24, Motorhead wrote:
I've got World Products Windsor Jr's on my 289, very mild porting done, and it makes good power all the way to 7500, and they don't even flow as much as standard AFR 165's, so I don't see why you would need to go as big as 205s.
To make some real power!
 

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Hotmaverick: I'm not going to argue with 289nate, but you might want to read the articles linked on AFR's web site here if you want some real world engine builds to see which heads best fit your combo:

http://www.airflowresearch.com/articles.htm
 

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My advice about a 205 head not being too big is based on the idea that hotmaverik is NOT building this for a driver. When I hear someone mention that rpm range I immediatly think of a track car. Max power from 6,500 - 7,800 rpm and not any concern for the lowend.

Those links to AFR builds are great. I just don't see any that are for a 306 that needs to make big power in the 6,500 to 7,800 rpm range.

I could be totally wrong on what this guy wants this engine for. He might be happiest with the 450hp 306 185 AFR combo that makes peak power just over 6,000 rpm and will fall on it's face with the hydro cam close to 7k rpm.


<font size=-1>[ This Message was edited by: 289nate on 2/22/06 11:18am ]</font>

<font size=-1>[ This Message was edited by: 289nate on 2/22/06 11:18am ]</font>
 

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Well you're definitely right there, if he chose a hydraulic cam then there's no point of going with 205s, or even 185s, because he'd never make it to 7K rpm. The main reason I'm saying 185s is because my 289 (292cid), which is very close to the same size engine as his, has no problem pulling to 7500rpm, and makes peak power in the neighborhood of 6300rpm, with heads that don't even flow as well as AFR 165s. I'm sure if I switched to comp 165s I'd pickup an easy 30-40hp, and probably even more than that at 7500rpm. However, I think that's all the head MY engine could handle, and switching to 185s would probably just cause a loss in torque with no gains in top end. If Hotmaverick is looking for a couple hundred more RPM than what I'm doing, with about 13 more cubes, I think he'd be in the same boat as I am, except probably being able to use just a little more airflow, so he might benefit from stepping up to the 185s. He might make the same, or even a couple more peak HP with the 205s, but I'll bet he'd loose some of the meat in the middle of the torque band around 4500-5000rpm because of the lower port velocity. But, I'm not any kind of expert, if anything I'm just a PC Dyno/Benchracing expert, but I think that carries some validity... it's at least a good teaching tool and better than no experience at all
 

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Just because your motor will make power to 7500 rpm with smaller heads does not mean that it wont make more power at 7500 rpm with bigger heads. If you want big power at high rpms out of a small motor go with the big heads. But be warned it will be a tempermental motor that lacks low end power. If you think about it a 200cc head is not that big, guys use winsor seniors on 302's in race applications and they have 200cc runners. I have a 302 with 185 cc ports and it makes great power from 2500 up, that is partly due to the cam as well. Be sure to match those big heads with s solid roller cam and big carb and single plane intake.
 

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Motorhead has it right. I was considering building a righ revving Pro Street high compression 302/306 with 500+ HP that reved to 8000 rpm and had peak power at about 7500 rpm. I chose AFR 165s, a 306S solid lifter flat cam, single plane intake, 750 cfm carb, 12:1 compression and long tube headers. I made a post about it on another forum and a Pro Street guy chimed in and said I was right on in choosing AFR 165s. Other Pro Street guys were using them on 302s and reving the heck out of them and producing boatloads of power.

To make max power and torque, you want the smallest ports possible that have the most flow...IOW, an efficient port and AFR 165s are very efficient ports. They are not huge, but they flow a bunch...perfect. Plus a 302 is not a big motor so the air flow requirements are not like what is needed for a 393 or 408, etc.

Heck...my poor little 331 with ported DOOEs with 160cc ports rev's like crazy to as high as I dare take it which has been nearly 7000 on occasion. The cam has a lot to do with this, but if the heads were choking it, I wouldn't have peak power at 6300 and power that only drops off 10-15 at 6600.

I honestly think there are several who fall into the bigger is better trap. If you were going to supercharge it, then maybe 185s would be a better choice, but otherwise, I strongly feel that 185s would make minimal HP gains if any and lead to torque loss on a naturally aspirated 302.

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Tracy Blackford: Corona, Ca
'65 FB Mustang 331 with 282S cam, fully preped 351W heads. T5z and 3.50 9" posi. 335 [email protected] RPM


<font size=-1>[ This Message was edited by: blkfrd on 2/23/06 2:05am ]</font>
 

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Is this a Street Engine or a Race Engine? Pro Street and Racing are two way different things, Reving to 7500 and making real power at 7500 are two different things...... 165's are way to small for a race engine with peak power in the 7500 range..............But on a pro street car the may work and let you get by, but they definetly are not the choice for a race engine. Same goes for the flat tappet cam its a compromise at best.

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1991 LX Mustang 347 C4 combo Mid 11's with the AC on.
1984 Mustang GT 460, Powerglide "Still putting it together" hoping for 9's !!

<font size=-1>[ This Message was edited by: dfree383 on 2/23/06 2:26am ]</font>
 

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On 2006-02-22 11:24, dfree383 wrote:
Is this a Street Engine or a Race Engine? Pro Street and Racing are two way different things, Reving to 7500 and making real power at 7500 are two different things...... 165's are way to small for a race engine with peak power in the 7500 range..............But on a pro street car the may work and let you get by, but they definetly are not the choice for a race engine. Same goes for the flat tappet cam its a compromise at best.

_________________
1991 LX Mustang 347 C4 combo Mid 11's with the AC on.
1984 Mustang GT 460, Powerglide "Still putting it together" hoping for 9's !!

<font size=-1>[ This Message was edited by: dfree383 on 2/23/06 2:26am ]</font>
Pro Street and Racing are not that different. If you think a 302 with 165s would fall on it's face at 6400 rpm even if the cam produces power beyond 6400, then I have to soundly disagree.

How much more power do you think a roller makes than a solid flat tappet...it may be more or it may not but it may not be as significant an increase as some may think. How much power is lost due to very stiff springs like the ones used by roller cams? Rollers have pros and cons just like flat tappet cams.

What if I said that a 302 with the parts mentioned in my previous post could make an estimated 500+ HP at 7500 rpm with open headers...would you say i'm way off base? If so, then how much? At what point does it become a race motor?

What is being gained by having a head port that has a significantly larger cross sectional ares than the intake runner that is feeding it? If the intake does not match the port cross sectional area of 205s then is there a mismatch? If a intake is purchased that does have the cross sectional area of the 205s, what happens to the engine's characteristics if the intake volume is large for that particular engine?...the engine becomes very peaky and has poor throttle response and has poor torque characteristics.

I don't want to argue, but I think you would be surprised what a properly designed 302 with 165s could do.

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Tracy Blackford: Corona, Ca
'65 FB Mustang 331 with 282S cam, fully preped 351W heads. T5z and 3.50 9" posi. 335 [email protected] RPM


<font size=-1>[ This Message was edited by: blkfrd on 2/23/06 2:55am ]</font>
 

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Again I agree with you for a ProStreet application requiring low speed operation (below 5000rpm) with a street minded convertor and gearing it would run good. And I didn't say it wouldn't work.

However For an engine operating above 5000 to 8000+ in a real racing application the 165's are WAY TO SMALL in fact the AFR heads do not flow as well as alot of other brands in the real word. I've seen them on the bench and you might just be shocked when everything is equalized. Same Bores, No Pipes or flow enhancing devices.

Flat tappet cams are a good cost effective choice. How ever again in a FULL Race Engine the Friction reduction, Increased Ramp Speed, and lift afforded by the roller lifters (you can make an argument about schuebeck lifters) are far superior to Flat Tappets. And again Prostreet and Race engines (not ones from the 60's) are vastly different in the duties they are required to do.

I would like to see your 12:1 306 with AFR 165's and a Comp cams 306S make 500hp on a real dyno. I'm not arguing it would't run good. 350 Real Crank HP will run low 11's if you set it up right, But Computer Dyno's are for Bench Racers and Guessing.

_________________
1991 LX Mustang 347 C4 combo Mid 11's with the AC on.
1984 Mustang GT 460, Powerglide "Still putting it together" hoping for 9's !!

<font size=-1>[ This Message was edited by: dfree383 on 2/23/06 4:25am ]</font>
 

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I don't think anybody is arguing in a bad sense. I think we're just discussing. Don't see anyone calling names. It's a very good discussion!

Pro Street and Racing are not that different. If you think a 302 with 165s would fall on it's face at 6400 rpm even if the cam produces power beyond 6400, then I have to soundly disagree.
I don't think anyone feels you can't make peak power at 7,500+ with 165's. I feel the dyno sheet will show that it does not climb in power the way a 306 designed around 205's will from 6,500 to 7,800. I'd want the most power in my intended rpm range. How much power? In a race car I'd take any overall increase in power in my range.

How much more power do you think a roller makes than a solid flat tappet...it may be more or it may not but it may not be as significant an increase as some may think. How much power is lost due to very stiff springs like the ones used by roller cams? Rollers have pros and cons just like flat tappet cams.
I agree. From what I've gathered a solid roller really benefits from the fact that you can get much more aggressive with the lobe profile. This can have the valve open at a higher lift for longer within a given duration. Not a real big deal on most street or street/strip motors. It is a big deal on a 7500-8500 rpm race motor.

What if I said that a 302 with the parts mentioned in my previous post could make an estimated 500+ HP at 7500 rpm with open headers...would you say i'm way off base? If so, then how much?
I'm sure that it's possible. I'd also love to see a dyno graph of one of these motors they have or can build. What mph has it run in the 1/4 mile and in what weight car? It would be even more potent in my opinion with the 205's and the right cam. Just to remind you Total Engine Airflow made a 607 hp 306 with just 12.5:1 comp and 205 tfs renegade heads. I think on the first pull it made 570hp at 7,800 rpm. I'd bet the power curve (which I haven't seen) is substantially greater than on your proposed 165 306 from 6000 through 7,800.

At what point does it become a race motor?
I feel that's for the owner to decide. I'd say it's when it can no longer be tolerated on the street by the owner. I'd rather drive a racecar on the street than bring a street car to the track (wish I had more $$$). Some may call it a racecar if there's not enough vacuum to operate power brakes. The engine builder will take into account some sort of street manners for a pro street build since it will by definition have to be able to hit the streets in some form. There are super fast street cars and super slow race cars.

What is being gained by having a head port that has a significantly larger cross sectional ares than the intake runner that is feeding it? If the intake does not match the port cross sectional area of 205s then is there a mismatch? If a intake is purchased that does have the cross sectional area of the 205s, what happens to the engine's characteristics if the intake volume is large for that particular engine?...the engine becomes very peaky and has poor throttle response and has poor torque characteristics.
That's why the design of the cam is VERY important (I also thought I was talking about a peaky engine from the start). A Victor Jr. will keep up with 205's after a little work (think it does OK just port matched).

I don't want to argue, but I think you would be surprised what a properly designed 302 with 165s could do.
You're not being argumentative in my book.
165's may suprise me, but I feel 205's on the right 302 could shock you.


Great discussion! Let's feel free to keep it up.
 

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On 2006-02-22 12:21, dfree383 wrote:

I would like to see your 12:1 306 with AFR 165's and a Comp cams 306S make 500hp on a real dyno. I'm not arguing it would't run good. 350 Real Crank HP will run low 11's if you set it up right, But Computer Dyno's are for Bench Racers and Guessing.
I'm not sure if your saying it will only make 350 HP or that i'm just a bench racer or both.


If 165s don't flow as advertised, then what do they flow? I can only go on what they advertise. I'd like to see what they really flow if it's different. I'd probably feel compelled to clean up the ports on a set of AFR "production" heads anyhow.

Why not AFR 225s...why stop at 205s on a 302. What do guys do that build race 427 windsors? Put AFR 225 race heads or similiar on? Ok...i'll pose a question to you...take the head intake volume and divide it by the ci of the engine. 165/302 and 225/427. Which has the larger intake volume to ci ratio...the 302 with only 165s on it! Does this mean anything without taking flow into account...maybe not but AFR heads are used on both and they both flow pretty darn well, and it helps to illiustrate a relationship of head volume to engine size or engine flow requirements. So what do we make of it...hummmmmmmm! Food for thought maybe...I may have to build this engine just to show the tach flying past 7000 rpm (in gear under load).

165s are not small (for a 302) and a 302 isn't big so where does bigger not become better?

I'd really like to build a 500 HP 289 with 165s but i can't find a good off the shelf forged short skirt piston to use with a 5.4 long rod like I can for a 302...an internal friction reducer that I would recommend to you hotmaverick302.

Oh...that brings up another issue...long rods...does a long rod promote more power in the real world because it makes the piston dwell longer at TDC, because the rod angle is reduced, or because it tends toward a smaller shorter skirt piston that reduces internal friction of the engine thus leading to more usable power? If it's because of the longer dwell at TDC, how much longer does the rod have to be to start making a difference? This is a question for more discussion if anyone cares to discuss...and I think I gave away part of the answer...I gotta go tune my bench...see ya


Oh yea, what would happen if someone actually went against the rod/stroke ratio grain and used short 5.155" 289 length rods when they designed a 331...what the heck could they be thinking!...why would they do such a thing?


That's enough self-deprecation for one post.

_________________
Tracy Blackford: Corona, Ca
'65 FB Mustang 331 with 282S cam, fully preped 351W heads. T5z and 3.50 9" posi. 335 [email protected] RPM




<font size=-1>[ This Message was edited by: blkfrd on 2/23/06 9:29am ]</font>
 
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