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Message started by tbalam on 04/21/07 at 12:34:13

Title: porting the intake?
Post by tbalam on 04/21/07 at 12:34:13

Does the intake have the same restrictions, i.e pressure drops, as the exhaust?

if you over port the intake are there any problems? THis is flow problems not damaging the head.

Title: Re: porting the intake?
Post by Greg_650 on 04/21/07 at 13:35:01

There's a lot of discussion on this area....flow, swirling, etc.

I polished mine up to the split and left it alone. All in all, I don't think much can be gained. The total intake area is still greater than the combined intake valve area...and besides, what goes in must go out. The exhaust valves are smaller.

I could be wrong...???

Title: Re: porting the intake?
Post by barry68v10 on 04/21/07 at 15:37:43

No, I don't think you're wrong Greg! The most improvement that can be made on this, and most other stock heads is the exhaust side. I've heard of guys using stainless intake valves on the exhaut side in American V-8's to gain "free power". Problem has been that intakes are not designed to handle the heat an exhaust valve can...

Title: Re: porting the intake?
Post by Max_Morley on 04/21/07 at 19:39:45

Think about the pressure difference on the intake side, somewhere from O -15 PSI depending on the throttle opening. about 5 at idle and almost 15 at WFO. The exhaust has about 4 times the compression value for pressure at peak lets say 150 x 4 = 600 PSI, so the pressure difference across the exhaust will be much more even as the piston approaches BDC . Max

Title: Re: porting the intake?
Post by justin_o_guy on 04/21/07 at 19:49:29

Then maybe the best thing to do with the intake would be to swirl & texture it so as to create as good an atomizor as possible & avoud smoothing it so much thet it creates droplets of gasoline on the walls? Is there some preffered ratio of intake area to valve area? Does it take Voodooo or just plain Majikk?

Title: Re: porting the intake?
Post by Greg_650 on 04/21/07 at 21:17:11

Max_Morley wrote:

Good point too. That little thing about ignition and "Bang" does change the pressures a good bit. Basically you have a helluva lot more velocity going out the exhaust side too:P

Title: Re: porting the intake?
Post by Greg_650 on 04/21/07 at 21:21:01

barry68v10 wrote:

"Free power". Hmmm. Think I got it. Never heard it before though (haven't done much automotive like that). You mean actually porting the head with equal size intake and exhaust valves?

Title: Re: porting the intake?
Post by barry68v10 on 04/22/07 at 03:39:56

Quote:

You mean actually porting the head with equal size intake and exhaust valves?

Yes. Although, getting a cam with a bigger exhaust lift and longer duration (exhaust only) can accomplish similar results and is cheaper/easier. You just can't duplicate the low RPM performance of a bigger exhaust valve with a smallish intake valve. If you reach your upper limit of lift and duration though, and have to get more exhaust out, then a bigger valve is your only choice. There are porting techniques which can help with any given size valve, but I don't know much about that...

Title: Re: porting the intake?
Post by barry68v10 on 04/22/07 at 03:44:24

BTW, anyone know what size intake and exhaust valves our Savages have? I know Lancer already posted the stock and Lancerized cam specs...

You liked that didn't ya....Lancerized ;D

Title: Re: porting the intake?
Post by Greg_650 on 04/22/07 at 06:56:50

Now what did I do with those measurements? Hmmm..

Here they are...

Intake = 33 mm or 1.3"
Exhaust = 28 mm or 1.1"

http://i21.photobucket.com/albums/b277/gmdinusa/HeadChamber_2528.jpg

Title: Re: porting the intake?
Post by barry68v10 on 04/22/07 at 07:48:03

The way that head is milled, you can't make round valves any bigger. Sure, there's room to the inside, but not on the outside. You could switch to oval valves and get LOTS of extra capacity on the Savage head.

If you started from scratch on this head, it would be no problem to use the same 1.3" intake and exhaust valves. The center of the exhaust valves would have to move inboard however, creating other "problems" to fix.

With such close sizes, I'd just go with a cam grind with the same intake lift and duration, and get exhaust lift and duration to match or exceed it... I wouldn't think it'd be worth the trouble to change valve sizes.

Total valve area is 1.9 square inches exhaust, and 2.65 square inches intake.

(compared with 2.01 square in. exhaust and 3.2 square in. intake area per cylinder for a high performance chevy 350 w/2.02 intake and 1.6 exhaust)

Translation: The Savage has more exhaust capacity and less intake capacity for its engine size than a HO chevy 350.

IMHO, the best cam grinds have equal intake and exhaust lift, and longer exhaust duration for the way I like to drive/ride...

Title: Re: porting the intake?
Post by Greg_650 on 04/22/07 at 08:14:45

barry68v10 wrote:

As you state...I'm pretty sure that the "Lancerized" Hard Chrome cam grind has the same lift and duration for the intake and exhaust.

Title: Re: porting the intake?
Post by thumperclone on 04/22/07 at 11:11:14

velocity....
www.mototuneusa.com
this guy D fills his ports.interesting theory, and he gets results!

Title: Re: porting the intake?
Post by verslagen1 on 04/22/07 at 14:08:52

Interesting concepts, and some bull...

If his engines were so sought after he could charge any price, yet he's running a website, and selling subscriptions like all the rich realestate molguls on tv. ;D

Title: Re: porting the intake?
Post by Reelthing on 04/22/07 at 21:43:50

Well there's been classic cases where D ports worked far better than O - the case of the 351 Cleveland factory 4-bbl heads we had ship'd to the US from the Aussies - see ford never sold such a thing in the US. Great big dang valves and ports - turned out the exhaust port was too big for lower rpms if you had the least bit of over lap on the cam - the D port plates made a big difference.

On the intake side much work is done around swirls and such - but also the velocity of the intake mixture - you want it as big as you can get it until the intake velocity slows down - then it's too big - the cam overlap effects it as well - anyone have a flow bench handy?

Title: Re: porting the intake?
Post by klx650sm2002 on 04/23/07 at 00:58:31

Greg_650 wrote:

Now what did I do with those measurements? Hmmm..

Here they are...

Intake = 33 mm or 1.3"
Exhaust = 28 mm or 1.1"

http://i21.photobucket.com/albums/b277/gmdinusa/HeadChamber_2528.jpg

KLX has inlet = 37mm
exhaust = 32mm

Clive W :D

Title: Re: porting the intake?
Post by barry68v10 on 04/23/07 at 02:17:27

Quote:

KLX has inlet = 37mm
exhaust = 32mm

100mm bore with bigger head does give you more area to play with...I guess that's one of the reasons for the 13hp difference for stock configuration.

Title: Re: porting the intake?
Post by Greg_650 on 04/23/07 at 05:18:30

klx650sm2002 wrote:

KLX has inlet = 37mm
exhaust = 32mm

Clive W :D

5 MM difference between valves in both engines....

Title: Re: porting the intake?
Post by Greg_650 on 04/23/07 at 05:21:26

Reelthing wrote:

The velocity will slow down if the intake is larger than the carb throat. Right?

Title: Re: porting the intake?
Post by LANCER on 04/23/07 at 06:48:10

klx650sm2002 wrote:

KLX has inlet = 37mm
exhaust = 32mm

Clive W :D

What is the stroke on the KLX?

Title: Re: porting the intake?
Post by Reelthing on 04/23/07 at 06:51:59

I believe so - as well as bigger than the valve area needs to keep it high - I have read the magic rate was around 300 ft per second.

The other area was always to back cut the intake valves - go from a tulip shape to a quarter on a stick this opens more valve area sooner - but too much back cut will cause the valve head to pop off.

Title: Re: porting the intake?
Post by verslagen1 on 04/23/07 at 09:24:44

Not that I do anything with flow dynamics...

I installed a superquiet bathroom exhaust fan recently. At first, I ignored directions and slapped it in with available ducting. (Manual? we don't need no stinking manual!) Huh, louder than the one it replaced! So I read the manual. For optimum performance, it needs 2 to 3' of straight ducting before turning to exit. OK, did that. SOB, it's quiet. I suppose it needs the straight to achieve laminar flow and possibly momentum.

OK, to reduce resistance to the intake you need to reduce surface variation. Micro pockets of vacuum and pressure causes areas of high velocity and low. Read friction. you want gradual change not sudden. HTHS. ;D

Title: Re: porting the intake?
Post by klx650sm2002 on 04/24/07 at 01:06:51

The bore and stroke on KLX is 100 x 83.

Clive W :D

Title: Re: porting the intake?
Post by Greg_650 on 04/24/07 at 05:14:10

The bore and stroke on LS is 94 x 94.