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#1
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906 head flow?
Does anybody have an idea what a slightly cleaned up 906 head will flow on the exhaust with a 1.81 valve? I'm trying to figure out the best header size for a warmed up 440 in a street/strip car.
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#2
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size your headers based on overall engine hp.
for around 500 hp, go 1 and 7/8. around 600 hp, go at least 2 inch. for a standard 440, at least 1 and 3/4 |
#3
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Thanks for the comeback Bob. According to the Desk Top dino I should be around 450 but you know how it goes, always looking for more.
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#4
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Quote:
Lots of fun ways to make more power. But overall airflow through the engine is the key. Best bang for buck is probably a cold air intake. http://ramairbox.com You get about 1.5% power increase for every 10 degrees you lower air inlet temp to carb. So lower it 50 degrees is 7.5% power increase, or about 35 hp on a 450 hp engine. I have the dual snorkle setup on my 496. |
#5
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Sounds like some good info Bob. I just need to figure out how I am going to do it with those dual Edelbrocks. I know one big single would be better but duals sure do have a WOW factor to consider. Thanks again..
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#6
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Quote:
I gotta agree with the wow factor :-) I sure have fun with mine! I got a second beater hood and built a scoop for my cold air induction. My old cam/head combo was too mild to efficiently use the dual quads but it did work. I have new heads and a bigger cam now so it's working very well! |
#7
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Oh WOW! That thing really looks good. Nice job Rich. What cam are you using. Mine is the .284/.484 hemi grind. Seems to work pretty well although my plugs are saying I'm a little rich. Go figure!
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#8
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On my 383 I put down 452 hp with a 1050 Dominator and the 1 7/8 headers are starting to choke me. With the 950HP carb I use normally the headers are fine. There are a lot of details on my setup I am not telling you but my point here is with the headers I would go with the 2" TTI's and never have to upgrade if you decide to put a set of Max Wedge heads on that motor.
Terry |
#9
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That sounds like a pretty hot 383. Sounds like bigger is better in the header world. Right now I have 1-3/4" and sounds like I may be missing some hp. Terry, have you dynoed your motor? I was wondering how you got that hp #. Has any one else used that Desk Top Dyno from Pro Racing?
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#10
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My motor was setup on an engine dyno. I have never used Desk Top Dyno. Friend of mine has Dynomation 5 and after putting all of my specs in the program, the output figures were within 10%.
383 .030 over Factory forged crank/Factory Rods 452 Heads, welded and ported to MW specs. Cut to 74CC combustion chamber - 10.01:1 Indy MW intake 950 HP Holley 545 lift extreme energy Cam The Dyno was done with headers into the shop exhaust (6" pipe) basically open exhaust and velocity stack instead of air cleaner. Witht he 950 I was still showing vacuum at 5500-6000 RPM's. Dominator solved most of vacuum but airflow efficiency began dropping indicating restriction in exhaust. The key to my setup are the heads. Based on airflow the calculated efficiency in areas was as high as 123%. I have a second set of 906 Heads ported the same way and the next build will be a 440. Air velocity should increase and i cant wait to see what they will do on that motor. You have to take dyno numbers with a grain of salt. I dynoed mine in 90* humid weather. Even at that point I was up to 93 SQ jets with no power valves. If i were to pull the motor now and run it in 30* weather and no humidity I could bump the numbers even higher. Now stick the motor in a car with 2.5" tailpipes and factory aircleaner that flows worse than the 1/2" water pipe in my house and all those numbers go out the window. I am not saying to avoid a goal HP but dont kill yourself over engineering the motor. Make it fun and enjoy it! If you try to max out every HP you can......your going to go insane. Every single setup out there is missing HP unless you are dyno tuningor track tuning it every time it comes out of the garage. 1 3/4 is kinda small but depending on your head flow, they might be fine for now. If you want to spend money to upgrade then consider what you might do in the future and possibly buy the 2" headers. This way if you ever buy new heads that will flow more, you have one less restriction. Budget is a factor too. Head flow is another number that you cant really gauge as concrete. Atmospheric conditions affect air flow and what a set of heads flow today may not flow in the summer. Elevation is a big factor, flow bench calibration is another one. My heads were ported and flow tested in GA, once up here they shows numbers less than the original porting numbers. Reason was temp, humidity, elevation and flow bench model. The key to all the number is they were exactly 18% lower across the board. The only way to truely judge a head is to put it up agains another one that you are considering. These are tests you read about in Mopar Muscle and that is why they do them. All tests must be done at the same conditions on the same bench with care taken to ensure consistant results. I have a set of ported 915 heads i want to flow against the MW heads and see how they compare. I wish I had a stock 915 head to also throw in the mix. Terry |
#11
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That sounds like a serious motor. Is it strip only? Mine is a milder version of a 440. .030 @ 10.5 with the hemi grind .484/.284 and the 906s that I dressed up a little. On top is Edls dual quad set up with two 600s just for fun. The 727 has Red line clutches and Kevelor bands. Definately a fun ride but nothing serious. Just a toy.
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#12
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Not sure i would consider it a serious motor. 450 on an engine dyno isnt all that great to me. Figure with install and drivetrain losses its prolly 350WHP tops.
I use it for street, I wanted to frequent the track but launching would be a chore since I dont want to cage the car. I made plans to sit down and design a cage that would still let me use the back seat and stock bench seat but I just bring myself to bend and weld one in. I might bend a few just for fun and sell them at cost of material down the road to play with different ideas. Your motor sounds like a great combo, being a 440 you will benefit from the longer stroke. I found it tricky to get past 500hp with the short stroke of a 383. I will get pictures of mine up this weekend. Terry |
#13
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According to my experience, bigger is not better as far as teh headers go. It all depends of the application. For example a 408 SB we built made 466 hp at 6000 rpm with 2" priamry headers, but it was practically dead below 3500 rpm. With smashed 1 5/8 cheapo headers it made 455 hp, but pulled cleanly off idle. BTW, it was with a 650 carb, and there was practically no vacuum in the intake.
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#14
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Launching is a chore and you can't be a serious racer without slicks but I'm afraid of those as they tend to bend things even if the frame is tied but there is a hand full of guys who mess around at the strip with street tires so it is fun. I will try to include a pic. Tried it before and was unsuccessful so there is no guarantee...... No, not working. Can anyone tell me how to include a pic in this message. When I try it a block comes up asking for a url? Wtf do I do with that?
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#15
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Dart, thats interesting about your 408 with the 2" headers. My son is running a 408 with 1-3/4 headers and the thing pulls like a freight train using the 484/284 hemi grind and a 750 Edl. I'm sure there are better cams out there but all that low end torque sure is impressive. I use the same cam in my 440 and it is alot of fun. It pisses the neighbors off some times though.
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