|
Head flow rate effect to HP ratings?
#706479
05/24/10 12:43 PM
05/24/10 12:43 PM
|
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
AutoEngineer
OP
member
|
OP
member
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
|
Hi guys, I am having a stroked 496 BB on the engine stand and I am in the middle of choosing the heads for it. I already have stock 440Source heads that flow on intake 290CFM@.600 valve lift, exhaust 220CFM@.600 lift. I just ran into CNC ported 440Source heads that flow a little better, intake 315CFM@.600 lift, exhaust 233CFM@.600 lift. The cam I am going to use will give almost .600 lift on the valve with 1.6 rockers The flow rate difference between these two heads is not a big one, on intakes 25CFM and exhausts 13 CFM. in percentages it's 8.5% and 6%. By experience can you estimate how much the head flow increase will effect to the HP rating? I know that exact numbers can't be given, but it would be nice to hear your experiences or real figures if you have had your engines dynoed after a head change.
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: AutoEngineer]
#706480
05/24/10 01:26 PM
05/24/10 01:26 PM
|
Joined: Oct 2005
Posts: 294
mi
vcummins
enthusiast
|
enthusiast
Joined: Oct 2005
Posts: 294
mi
|
Quote:
Hi guys,
I am having a stroked 496 BB on the engine stand and I am in the middle of choosing the heads for it. I already have stock 440Source heads that flow on intake [Email]290CFM@.600[/Email] valve lift, exhaust [Email]220CFM@.600[/Email] lift.
I just ran into CNC ported 440Source heads that flow a little better, intake [Email]315CFM@.600[/Email] lift, exhaust [Email]233CFM@.600[/Email] lift.
The cam I am going to use will give almost .600 lift on the valve with 1.6 rockers
The flow rate difference between these two heads is not a big one, on intakes 25CFM and exhausts 13 CFM. in percentages it's 8.5% and 6%.
By experience can you estimate how much the head flow increase will effect to the HP rating?
I know that exact numbers can't be given, but it would be nice to hear your experiences or real figures if you have had your engines dynoed after a head change.
Try to get some mid lift #s from .300-.500 and compare the two. make sure your not sacrificing #s at mid lift to get A good upper lift #s if you are the 315 will be A instant loss of power. If you cant get it sooner your not going to get it later.
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: vcummins]
#706482
05/24/10 01:56 PM
05/24/10 01:56 PM
|
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
AutoEngineer
OP
member
|
OP
member
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
|
Quote:
Quote:
Hi guys,
I am having a stroked 496 BB on the engine stand and I am in the middle of choosing the heads for it. I already have stock 440Source heads that flow on intake [Email]290CFM@.600[/Email] valve lift, exhaust [Email]220CFM@.600[/Email] lift.
I just ran into CNC ported 440Source heads that flow a little better, intake [Email]315CFM@.600[/Email] lift, exhaust [Email]233CFM@.600[/Email] lift.
The cam I am going to use will give almost .600 lift on the valve with 1.6 rockers
The flow rate difference between these two heads is not a big one, on intakes 25CFM and exhausts 13 CFM. in percentages it's 8.5% and 6%.
By experience can you estimate how much the head flow increase will effect to the HP rating?
I know that exact numbers can't be given, but it would be nice to hear your experiences or real figures if you have had your engines dynoed after a head change.
Try to get some mid lift #s from .300-.500 and compare the two. make sure your not sacrificing #s at mid lift to get A good upper lift #s if you are the 315 will be A instant loss of power. If you cant get it sooner your not going to get it later.
Yep, that's good advice.
I have asked from 440Source the flow chart of the non CNC'ed heads but they have not supported them even I have already asked several times.
Anyone of this forum members having a flow chart of 440Source standard heads?
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: AutoEngineer]
#706484
05/24/10 02:04 PM
05/24/10 02:04 PM
|
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
B1Fish540
master
|
master
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
|
For a motor that size, why not get the most out of your heads? I know 440Source uses Jeff at Mondern Cylinder head. I'm sure if anybody knows the true out-of-box numbers he does. That said, I've seem people post munbers more in the 270 cfm range. Jeff gets them up to 320+ cfm. Thats a good 50 cfm increase, Mulyiply that x 2 = 100 hp. So, you get about 100 hp for 1000 bucks, if that is worth it to you, then, imho, have them ported.
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: Cab_Burge]
#706485
05/24/10 02:14 PM
05/24/10 02:14 PM
|
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
AutoEngineer
OP
member
|
OP
member
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
|
Quote:
It seems that there is a standard of two HP per each CFM on the heads, maybe one of the more knowleable head porters or engines guys with expereinces of swapping heads from unported to ported will chime in  BTW, big motors like and need big CFM and camshafts  That much I do know  
I was estimating by myself that the HP rating would increase something in between by the percentages of flow increase. In this case it might be 35 to 50 HP. So the theory of two HP per each CFM gives almost the same figures
So I guess giving more cam to the engine would give better HP/$$ ratio ???
|
|
|
Post deleted by Defbob
[Re: AutoEngineer]
#706486
05/24/10 02:18 PM
05/24/10 02:18 PM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
|
|
|
Re: Head flow rate effect to HP ratings?
#706487
05/24/10 02:22 PM
05/24/10 02:22 PM
|
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
B1Fish540
master
|
master
Joined: Sep 2008
Posts: 2,840
Flint, Michigan
|
Quote:
low lift numbers are very important sometimes more so than the highest one. you could have less at the top but outperform the head that shows more at max lift.
ya, but, on an oem type head? Typically, like the ones bryan posts, they pick up across the whole spectrum.
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: B1Fish540]
#706488
05/24/10 02:33 PM
05/24/10 02:33 PM
|
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
AutoEngineer
OP
member
|
OP
member
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
|
Quote:
For a motor that size, why not get the most out of your heads? I know 440Source uses Jeff at Mondern Cylinder head. I'm sure if anybody knows the true out-of-box numbers he does. That said, I've seem people post munbers more in the 270 cfm range. Jeff gets them up to 320+ cfm. Thats a good 50 cfm increase, Mulyiply that x 2 = 100 hp. So, you get about 100 hp for 1000 bucks, if that is worth it to you, then, imho, have them ported.
100 HP for 1G, is not so bad result
The formula of CFM X .257 X number of CYL = HP would give approx the same HP increase, IF the OTB Stealths flow only 270 CFM and after Jeff's porting they flow 320 CFM.
Hey, I will consider this head update issue once again to get some more 
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: AutoEngineer]
#706489
05/24/10 02:35 PM
05/24/10 02:35 PM
|
Joined: Aug 2003
Posts: 43,214
Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,214
Bend,OR USA
|
Quote:
Quote:
So I guess giving more cam to the engine would give better HP/$$ ratio ???
The cam can affect the power band, more duration tends to take away bottom end and add on the upper end to some extent, lobe seperation angle has similar affects also  I would look at a cam with 250 to 265 degrees at .050 on a 106 to 110 lobe seperation angle with as mauch lobe lift that I could get for your motor  That kind of cam will sound pretty nasty at idle and up to 2000 RPM, widening the lobe angle will tend to calm it down some down low in the RPM band while raising the peak torque and HP RPM  I did a head swap on my street motor in my Duster, 512 low deck. I took off a set of ported 906 iron heads with big valves and put on a set of CNC Eddy RPM heads with the same size valves as the 906 had, the 906 intakes flowed 266 at .600 on a Super Flow 600 bench, the Eddy heads intakes flowed 310 at .600 on the same bench. The car ran a best of 10.69 ET at 124.5 MPH with the iron heads and ran 10.43 at 128.6 MPH with the Eddy heads  I did swap rockers from a set of CAT 1.6 aluminum rollers(check to be only 1.54 at the retainers  ) due to shaft wear to a set of Harland Sharp 1.6 aluminum roller that check out to be 1.64 at the retainers Buy the good heads now
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: 451Mopar]
#706493
05/25/10 02:13 PM
05/25/10 02:13 PM
|
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
AutoEngineer
OP
member
|
OP
member
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
|
Quote:
My question is how is the engine going to be used?
If your racing with it and need the extra power, then spend the $$$$ and port the heads, use a large cam, and setup the converter/gear to work with it.
If it is a street car, how often will it really be raced, and how could the extra $$$$ be better spent or saved?
It's a 1970 Challenger, mainly a street car, but occasionally used at 1/4 mile or stop light races.
Here's some specs of the engine and drivetrain, Comp XR292HR-10 hydraulic roller cam, 1.6 roller rockers, 2" headers, MP M1 intake, B&M 3000 rpm stall, 3,55 gears
My target is to run with it to mid or high 11's. That would be enough to fill my appetite for speed, atleast for a short time 
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: Dodgem]
#706494
05/25/10 02:34 PM
05/25/10 02:34 PM
|
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
AutoEngineer
OP
member
|
OP
member
Joined: Jul 2008
Posts: 179
Up in the North and Far Away
|
Quote:
I think 440source numbers right out of the box are way bogus. I hand ported a set of 440 source and can tell you they are way optimistic on their OOTB numbers.
Hears what a Friend got stock now this flow bench may be a tad stingy (hope it is by my indy head flow numbers)
Those are interesting figures.
Looks like the flow was not much increased after the .400 lift, only 10 CFM to .500 and from .500 to .700 lift almost the same rate ~244/5 CFM
Anyone else having similar results?
440Source is marketing that those heads flow 290CFM @.600 OOTB 
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: AutoEngineer]
#706496
05/25/10 03:33 PM
05/25/10 03:33 PM
|
Joined: Jan 2003
Posts: 75,043
U.S.S.A.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,043
U.S.S.A.
|
Quote:
440Source is marketing that those heads flow 290CFM @.600 OOTB
Yes they are , don't hold your breath waiting for flow numbers, they never produced any that I ever saw. The claim when they first came out was ABOUT 290cfm at .600 lift , testing By trusted sources showed the REAL numbers .
|
|
|
Re: Head flow rate effect to HP ratings?
[Re: AutoEngineer]
#706497
05/25/10 03:48 PM
05/25/10 03:48 PM
|
Joined: Sep 2005
Posts: 1,328
St. Louis, MO
mopardamo
pro stock
|
pro stock
Joined: Sep 2005
Posts: 1,328
St. Louis, MO
|
Quote:
Quote:
My question is how is the engine going to be used?
If your racing with it and need the extra power, then spend the $$$$ and port the heads, use a large cam, and setup the converter/gear to work with it.
If it is a street car, how often will it really be raced, and how could the extra $$$$ be better spent or saved?
It's a 1970 Challenger, mainly a street car, but occasionally used at 1/4 mile or stop light races.
Here's some specs of the engine and drivetrain, Comp XR292HR-10 hydraulic roller cam, 1.6 roller rockers, 2" headers, MP M1 intake, B&M 3000 rpm stall, 3,55 gears
My target is to run with it to mid or high 11's. That would be enough to fill my appetite for speed, atleast for a short time
Hello,
You will get what you want with them stock more than likely. I would not CNC port them at this time. Save the bucks and pocket port and you will hit your mark for sure.
Damon
|
|
|
|
|
