 Head flow, 2.0L vs 1.8 |
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| KevinP |
 Dec 22 2005, 09:50 AM
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#1
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Member  Group: Members Posts: 205 Joined: 16-November 04 From: Orlando,FL Member No.: 3,127  |
I'm trying to research the percentage of flow difference (stock of coarse) between the 2.0L head and the 1.8L. Does any one how much?
What kind of difference running the larger valve set-up on both heads? (%) TIA KP |
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| sanman |
Dec 22 2005, 10:01 AM
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#2
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Leaving California Group: Members Posts: 341 Joined: 17-June 04 From: Houston, TX Member No.: 2,219 Region Association: None |
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| Katmanken |
Dec 22 2005, 10:07 AM
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#3
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You haven't seen me if anybody asks... Group: Members Posts: 4,738 Joined: 14-June 03 From: USA Member No.: 819 Region Association: Upper MidWest |
It's not just head flow..
A lot of the 2L head power comes from the combustion chamber shape and plug location. After all, the 2.0L head is the only production head designed by the factory racing team... The answer to your questions is it depends.... It really depends on how big are the valves, how big is the intake (carbs EFI), what cam, what exhaust, what cylinder size, what rpm range, etc... In some cases smaller is better and in others bigger is better. So, head flow rate is good but not all the pieces to the puzzle. Sorry for the vague answer, but don't just go by head flow. Len and Jake have modified new 1.8's to have the 2.0L plug location. Check their web sites. Ken |
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| Jake Raby |
Dec 22 2005, 11:49 AM
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#4
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
I have the data, but its not something we share.
I'll tell you now thet the plug location of the 2.0 is good for 5% more power than the flow differences. Thats a huge percentage of my engines receive relocated spark plugs..... Bigger is seldom better. |
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| fiid |
Dec 22 2005, 05:16 PM
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#5
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Turbo Megasquirted Subaru Member Group: Members Posts: 2,827 Joined: 7-April 03 From: San Francisco, CA Member No.: 530 Region Association: Northern California |
Jake - no specifics required, but do the sodium filled valves make a big difference?? (5% is a big diff in my mind (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) ).
Sorry for the hijack. |
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| Bleyseng |
Dec 22 2005, 06:14 PM
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#6
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
they were that way to help them last longer due to the cam timing being setup to run the engine hot. |
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| Dave_Darling |
Dec 22 2005, 06:28 PM
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#7
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914 Idiot Group: Members Posts: 14,986 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California 
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The idea is that the sodium melts (which it does at pretty low temperatures) and then sloshes back and forth inside the valve stem. When it is at the valve head end, it picks up some of the heat from the head. When it is up inside the stem proper, it gives off that heat to the valve stem, which then goes into the valve guide. Effectively, this gets some of the heat from the head of the exhaust valve (one of the hottest places in the engine) into the cylinder head, which is also pretty warm but has cooling fins and forced air flow to keep it from getting overly hot.
Now you know why having decent valve guides is important--they are one of the main cooling paths for the valves! --DD |
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| KevinP |
Dec 24 2005, 12:16 PM
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#8
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Member Group: Members Posts: 205 Joined: 16-November 04 From: Orlando,FL Member No.: 3,127 |
Sorry, gang I think you might have misunderstood my post. I was only intrested in the difference in the flow rates, not percentage of power between the two heads.
Pretty much common knowledge the 2.0L head has a better flow rate. The info is just a ball park figure not a exact average CFM rate. It just saves me from putting the two on a flow bench , doing the math and seeing for myself. Why, I'm a Motorhead! and just plain curious..... KP out (IMG:http://www.914world.com/bbs2/html/emoticons/flag.gif) |
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| Dominic |
Dec 24 2005, 05:49 PM
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#9
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Dominic Group: Members Posts: 992 Joined: 14-January 03 From: Vacaville, CA Member No.: 149 Region Association: Northern California |
A machinist I know back in Sacramento once told me that it would take 8 hours of work on a 1.7 or 1.8 head to match the flow of a stock 2.0L head. I don't know if that answers your question. |
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| Jake Raby |
Dec 24 2005, 07:15 PM
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#10
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Sodium filled valves suck... They were technologically advanced in the 1970s, but now we have stainless steel valves that FAR supercede them in durability... When the sodium filled valve break, they take out the entire engine with their own "Mini explosion" that makes the wallet open VERY far in a split second.....
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| KevinP |
Dec 27 2005, 07:16 AM
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#11
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Member Group: Members Posts: 205 Joined: 16-November 04 From: Orlando,FL Member No.: 3,127 |
Hey Jake,
I haven't never seen what kind of damage a sodium filled valve will do to a engine if it ever came apart or kissed a piston and broke, but I can only imagine this is an awsome site!!! Don't have any pics of these kind of melt downs do you? Thanks' KP out (IMG:http://www.914world.com/bbs2/html/emoticons/flag.gif) |
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| Jake Raby |
Dec 27 2005, 08:37 AM
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#12
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Yeah, I have a few... email me.
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| r_towle |
Dec 27 2005, 08:44 AM
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#13
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Custom Member Group: Members Posts: 24,574 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States
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Hi Jake, merry xmas...wlecome back after the short break...
I have a polish question.... Is it worth the effort to polish the chamber and ports...not change the shape...just polish...? Or, is that gonna change the heat exchange of having a rough port? Rich |
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| Jake Raby |
Dec 27 2005, 09:39 AM
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#14
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
A super smooth finish can actually cause issues in the ports, especially the intake on carburated engines due to fuel mixture...
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| r_towle |
Dec 27 2005, 11:40 AM
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#15
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Custom Member Group: Members Posts: 24,574 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States
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good, another thing I dont have to do.
Rich |
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