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  #31 (permalink)  
Old 08-20-2014, 10:09 PM
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Quote:
Originally Posted by vinniekq2 View Post
the point I was making is that you cannot say a 200 cc runner heads is good to "X" rpm or "X" cubic inches

The flow numbers are where you start
that gives you a potential horse power out put.
Then you find the cam design that will extract that flow from your heads and at the RPM that matches your cubic inches and desired rpm range (355 Vs 383 as an example)
The you figure out what compression ratio you need to match the heads and combustion chamber volume and pistons to get the correct DCR

now you know where the engine you chose will operate best at in the rpm range that takes full advantage of your combination

choose carb size ,double pumpers work just fine on automatics or standards,as a matter of fact the carb doesnt even know whats bolted to the flywheel,could be a propeller,,,,
choose an intake that works best with the flow you require,most often a dual plane intake for the street to match street engine rpm s most used
(everytime I drive my car I reach 6,000 rpm,you may not do that if the power scares you)
pick the correct diameter long tube headers for your engines power level,add a very free flowing mandrel bent system. I recommend full 3" with X pipe

Somebody is a faithful follower of the marketing hype. Probably would buy platinum pistons if the ads in Hotrod told him too.



There actually is a right way to do things, but this isn't it. Good for selling products though.




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  #32 (permalink)  
Old 08-20-2014, 10:28 PM
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https://www.airflowresearch.com/dyno.php

I'm sure there was several dyno pulls with several adjustments to get these advertising charts but it's at least something to look at.

Two of the best engine building books I've ever read.

http://m.summitracing.com/parts/sad-sa24

http://m.summitracing.com/parts/sad-sa21

Last edited by crussell85; 08-20-2014 at 10:34 PM.
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  #33 (permalink)  
Old 08-20-2014, 11:12 PM
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are you challenging me?

Quote:
Originally Posted by ap72 View Post
Somebody is a faithful follower of the marketing hype. Probably would buy platinum pistons if the ads in Hotrod told him too.



There actually is a right way to do things, but this isn't it. Good for selling products though.
platinum plugs are good,,,lol

If you are challenging me to a performance show down AP72? I accept. Hows your 302 coming? Maybe I could build a 283 and we could do some comparitive driving?
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  #34 (permalink)  
Old 08-20-2014, 11:24 PM
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Quote:
Originally Posted by ap72 View Post
There actually is a right way to do things, but this isn't it. Good for selling products though.
Like Ricky Ricardo used to say to Lucy, "splain it to me". Maybe we're all missing something so tutor us please.
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  #35 (permalink)  
Old 08-21-2014, 08:35 AM
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Quote:
Originally Posted by vinniekq2 View Post
platinum plugs are good,,,lol

If you are challenging me to a performance show down AP72? I accept. Hows your 302 coming? Maybe I could build a 283 and we could do some comparitive driving?
I haven't wokred on it in a while, took a trip to the junkyard a few weeks ago to get some missing plug connectors and sensors and an EDIS 8 setup but most of my car tim has been spent on my CJ7 and I've had very little car time since my dad decided he's building an inground pool, with no outside contractors. Since I'm the family civil engineer and worked construction for a while my ongoing participation is assumed. I've spent about half the weekends of my summer digging a pit or in a pit- that will soon be a pool.

I probably won't get to touch the 280z again until the leaves change color.

As for "splainin' it" the cc's on a sbc port can be used to calculate average cross-sectional area, a sbc port is approximately 5.7" long (give or take .05" based on design) so you can then figure that a 200cc port would have an average cross section of 2.14 sqin. Now obviously the port is not uniform as you get a little bulge around the short side and it gets a little narrow at the pushrod pinch but you can probably also assume that for a well designed aftermarket head with a 2.14 average csa your minimum csa will be about 1.9-2.0 sqin. Older heads don't have as uniform of a port but the new ones are pretty good.

Why is the 2" min csa important? This is where you're going to need to do some math.

RPM = (CA * 690) / (0.00353677 * s * b^2)

The 690 number is maximum velocity through a port, and the CA is minimal cross-sectional area. 690 is a BEST CASE scenario btw, you're looking at a professionally developed racing port to hit that mark, 600-650 is more common for the standard current aftermarket heads.

The minimal crosssectional area given by this calculation is the limit set before the port goes into choke or stalls out. If it does go into choke then you are going to start needing excessive cam duration to compensate and you'll start sacrificing significant power below peak. If it is too large then your port velocity will not be adequate and you will again sacrifice significant power below peak- BUT this can be "crutched" by lowering your cam duration but you will have a lazy port that is less responsive and your overall VE will still drop.

So, if you run that calculation you find that in a "best case" scenario your absolute minimal CSA on a perfectly developed racing port seeing 690 fps peak velocity before stall is 1.87 sqin. This would give you a minimal head volume of about 185cc's if you account for the transitions and is a perfectly developed port. Using a more realistic number of 650fps (still damn good and not achievable by all heads on the current market) you come up with a minimal CSA of 1.99 sqin giving you an approximate minimal port volume of...

drum roll please!


200cc's.


BTW, I encourage you to go check the minimal CSA's on 200cc heads, a well developed one will come out to about 2 sqin at the pushrod pinch, usually where the choke point is in a standard sbc head. Not all of them do though and some of them are actually significantly smaller.


A head can flow all you want, but nothing will make it pass sonic choke, port and valve sizing come first, then you can look at flow numbers to get an idea of the port and valve job efficiency.



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  #36 (permalink)  
Old 08-21-2014, 11:19 AM
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Got a quote from Patrick at Prosystems on a carb.

"For your Street/Road Race program, we can build you one of our XC series HP Gasoline double pumpers that offers great performance, incredibly quick throttle response and can be set up to be perfect for your application.

It has the good HP Series main body, bowls and blocks in a polished finished, our adjustable air bleed configuration, non-stick gaskets, Wedged floats (to offset G-forces), CNC Billet baseplate, rear anti-siphon mods (for hard braking), a complete wet-flow portfolio, a real sharp piece with stepped dog leg boosters, the new big sight glass bowls, VENOM II Black Billet metering blocks and hi-flow needle and seats.

Just bolt on and go.

Typically I see a 20-30 hp improvement over an off the shelf unit with much better driveability.

We'll size it for the exact cfm range when it is on the wet flow bench to match your programs needs.

But it'll probably end up being in the 780-800 REAL cfm range.

Its priced at $670.00 and UPS freight Continental USA is only $18.00

If this works for you, just e or call me wth a Credit Card # when you're ready and I can get it built.

We are on a 4 day build time.

Heres a link to a photo and some more info:

CIRCLE TRACK/ROAD RACING SERIES
"

What are your thoughts? Stick with a more "streetable" off the shelf carb, or ya'll think this would be a smiles for miles setup, given the price?
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  #37 (permalink)  
Old 08-21-2014, 11:32 AM
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X I bought my 950 HP from Pat. I bolted it on and so far changed one jet size only. It works out of the box as he says. I would say buy an 850 for your engine,,,,
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  #38 (permalink)  
Old 08-21-2014, 11:36 AM
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Quote:
Originally Posted by Xcrunner318 View Post
Got a quote from Patrick at Prosystems on a carb.

"For your Street/Road Race program, we can build you one of our XC series HP Gasoline double pumpers that offers great performance, incredibly quick throttle response and can be set up to be perfect for your application.

It has the good HP Series main body, bowls and blocks in a polished finished, our adjustable air bleed configuration, non-stick gaskets, Wedged floats (to offset G-forces), CNC Billet baseplate, rear anti-siphon mods (for hard braking), a complete wet-flow portfolio, a real sharp piece with stepped dog leg boosters, the new big sight glass bowls, VENOM II Black Billet metering blocks and hi-flow needle and seats.

Just bolt on and go.

Typically I see a 20-30 hp improvement over an off the shelf unit with much better driveability.

We'll size it for the exact cfm range when it is on the wet flow bench to match your programs needs.

But it'll probably end up being in the 780-800 REAL cfm range.

Its priced at $670.00 and UPS freight Continental USA is only $18.00

If this works for you, just e or call me wth a Credit Card # when you're ready and I can get it built.

We are on a 4 day build time.

Heres a link to a photo and some more info:

CIRCLE TRACK/ROAD RACING SERIES
"

What are your thoughts? Stick with a more "streetable" off the shelf carb, or ya'll think this would be a smiles for miles setup, given the price?
If you're buying a $700 carb why would't you just go EFI instead? Pay more for less performance? Doesn't make sense.



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  #39 (permalink)  
Old 08-21-2014, 11:41 AM
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If you're buying a $700 carb why would't you just go EFI instead? Pay more for less performance? Doesn't make sense.
Are you assuming I have the electrical setup to easily do EFI?
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  #40 (permalink)  
Old 08-21-2014, 11:50 AM
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Are you assuming I have the electrical setup to easily do EFI?
meaning a wire stripper/cutter? You can get one at Harbor Freight for $4- it doesn't add significantly to the cost. You can also use a coupon to get one of their multimeters for free.

The best part is you can use these same tools on a LOT of projects around the house.



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  #41 (permalink)  
Old 08-21-2014, 11:53 AM
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Originally Posted by ap72 View Post
meaning a wire stripper/cutter? You can get one at Harbor Freight for $4- it doesn't add significantly to the cost. You can also use a coupon to get one of their multimeters for free.

The best part is you can use these same tools on a LOT of projects around the house.
I guess I'm just confused because all the EFI systems I'm looking at are in the 2k range...definitely not cheaper. Unless you have something different in mind? I don't have any doubt I could do it - you just follow the instructions given with the kit, just can't find this less for more pricing.
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  #42 (permalink)  
Old 08-21-2014, 12:04 PM
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not defending carbs,,

Quote:
Originally Posted by ap72 View Post
If you're buying a $700 carb why would't you just go EFI instead? Pay more for less performance? Doesn't make sense.
fuel injection has many advantages
cold starts
altitude and weather adustments
fuel economy,etc

But? at WFO which system develops the most horse power?
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  #43 (permalink)  
Old 08-21-2014, 01:00 PM
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Originally Posted by vinniekq2 View Post
fuel injection has many advantages
cold starts
altitude and weather adustments
fuel economy,etc

But? at WFO which system develops the most horse power?
Depends on the setup, I've never seen anyone reproduce the same setup from carb to efi, carb has a lot more headaches to deal with which gives efi a huge advantage in manifold design, also a "carb" is not just a carb- there are a lot of different designs and the same holds true for efi. Efi has many design advantages that should allow it to make more power, but one test will show a carb with a slight edge, the other with efi having a slight edge- it seems the superior design do to less restrictive requirements hasn't really been fully max'ed out.

And now there on direct injection which shows significant gains over both.



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  #44 (permalink)  
Old 08-21-2014, 01:12 PM
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Originally Posted by Xcrunner318 View Post
I guess I'm just confused because all the EFI systems I'm looking at are in the 2k range...definitely not cheaper. Unless you have something different in mind? I don't have any doubt I could do it - you just follow the instructions given with the kit, just can't find this less for more pricing.
stealth ram intake manifold- $350
injectors- $200
fuel rail- $50
throttle body- $100 for a reman, $15 for JY direct.
microsquirt controller- $340

$960-ish

VS

RPM intake manifold- $200
Carb- $700

$900- ish

Pretty much the same cost, BUT microsquirt also gives you spark control and MUCH easier tuning and better fuel management for on the road conditions.

If you are pinching pennies than going with a $400 carb may make sense if you don't plan on driving it often but a $700 carb just seems silly.



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Old 08-21-2014, 03:35 PM
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Quote:
Originally Posted by ap72 View Post
stealth ram intake manifold- $350
injectors- $200
fuel rail- $50
throttle body- $100 for a reman, $15 for JY direct.
microsquirt controller- $340

$960-ish

VS

RPM intake manifold- $200
Carb- $700

$900- ish

Pretty much the same cost, BUT microsquirt also gives you spark control and MUCH easier tuning and better fuel management for on the road conditions.

If you are pinching pennies than going with a $400 carb may make sense if you don't plan on driving it often but a $700 carb just seems silly.
I guess another difference is that I'm not having to buy the intake, I already have it, like I said previously.
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