AMS EVO X Head Comparison
Feb 14, 2008, 09:12 PM
#16
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Martin,
If you would like I can flow that head for you and have it back up to you before you knew it was gone. I have a Superflow 1020 Pro Bench and I could lay that 4B11 chart over the EVO 4G head, as well as other stuff like the 1g, 2G, Cosworth, and some others. I'm located in Indianapolis.
If you would like I can flow that head for you and have it back up to you before you knew it was gone. I have a Superflow 1020 Pro Bench and I could lay that 4B11 chart over the EVO 4G head, as well as other stuff like the 1g, 2G, Cosworth, and some others. I'm located in Indianapolis.
Feb 14, 2008, 09:34 PM
#17
A little off topic, but while I'm talking about this goo...the 4G has some issues that most machine shops and head porters overlook. One of those is that you can NOT do proper valvejob on a 4G head without using a torque plate to simulate the head being torqued to the block. If you do one without the plate, the instant you torque the head to the block the seat is deformed and won't seal properly. I see it all the time. Guys do a real nice valvejob, vacuum test it and it seals with flying colors, then they install the head and the motor leaks down 15-20%. A VJ with a torque plate will achieve a near perfect seal after the head is torqued. That problem is taken futher when guys do a 1m os valve without installing a larger seat...happens all the time and there is lots of power to be had in simply doing a proper valve job
Cheers
Feb 14, 2008, 09:52 PM
#18
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I am not buying. If what you say is true then a brand new head or low mile head would show poor seal when you check it without torque plate. And that is simply NOT the case. I have checked seal of many new and very low mile heads and the seal is great without a torque plate. Sorry there isnt enough distortion to make the seat go out of round that much. In case of block the studs are pulling right next to the bores, so there is measurable distortion of bores. In case of the head the studs are compressing the head but the valve seats are at quite a distance from that distortion.
As for cutting the seat without a plate I am just giving feedback from countless heads...if you don't agree then you don't agree. Every seat that was cut without a plate distorted on the block...period. Once we started using a torque plate...problem solved. Our Spec Miata motors are the same way. And if you are allowing distortion of the bores and deem that acceptable...I guess I should wonder no more. That is exactly why we use a torque plate for every hone also
Most places won't do that considering the price of a torque plate for every different kind of motor they work on.
Feb 14, 2008, 10:40 PM
#19
94awdcoupe, drag is correct in this matter. I'm not saying that there will always be a distortion of the valve seat when not using a torque plate, but it does happen quite often from what I've read. Now, I don't know that much about intricate internal motor work, but this is pretty straight forward. Not trying to be a dick, but I'm just calling it how I see it. BTW DRAG, I would be very curious to see the results of flow bench testing the 4b11 head against the 4g63. If you do get a chance to do this, make sure to post it up. Thanks man.
Feb 14, 2008, 10:47 PM
#20
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I have seen valves leak after being torqued. Its usually attributed to torquing beyond the factory torque specs (ie A1 studs @ 100 lbs) and or o-ringed blocks with too much o-ring protrusion.
Feb 15, 2008, 05:36 AM
#21
I am not a newbee. I went to the trouble of building a torque plate for the 4g63 block. It is about 6 years old now. Bore distortion measured at .0008 without plate. I am just saying I have never seen any evidence of head distortion in my work with the 4g63. Leak checking valves is dirt bag easy to do. Its a 2 minute test. spraying carb cleaner in the ports will pinpoint distorted seat. Drag is claiming every one will distort as a matter of fact. I have checked some 20 heads with low time and never seen this distorted seat manifest. Yet Drag cant explain that? From his knowledge every one should leak before being bolted to block or torque plate. The last head I built for my car had cut seats and had 4% leak down on all 4. No head torque-plate used. Heads with lots of miles always have distorted seats. This is because they warp over time with heat. Like I said earlier the studs are less than 1/4 inch from bores. Very close. And there is only .0008 distortion. The valve seats sit some 1.00 inch from the studs. How much distortion is there that far away? Plus its a distortion form compression of head. Unlike the block studs which are trying to pull threads out.
Its a good discussion if you dont get your panties in a wad. I believe head distortion is a problem with after market heads studs torqued to the moon. The early 4g63 had beefy looking studs, The later models switched to thinner studs. Since aluminum expands more than cast iron with heat, I believe mistu made the 2nd generation of studs expand more to help relieve this distortion. VW did the same thing 50 years ago going from 10mm studs to 8mm. The valve guides would also be affected from this distortion.
Also a torque plate is only half the trick. The other half is heating the part to operating temp before working on it.
Its a good discussion if you dont get your panties in a wad. I believe head distortion is a problem with after market heads studs torqued to the moon. The early 4g63 had beefy looking studs, The later models switched to thinner studs. Since aluminum expands more than cast iron with heat, I believe mistu made the 2nd generation of studs expand more to help relieve this distortion. VW did the same thing 50 years ago going from 10mm studs to 8mm. The valve guides would also be affected from this distortion.
Also a torque plate is only half the trick. The other half is heating the part to operating temp before working on it.
Last edited by 94AWDcoupe; Feb 15, 2008 at 05:46 AM.
Feb 15, 2008, 08:52 AM
#22
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94AWDcoupe - No one is getting their panties in a bunch bro...we are just talking about it. I tell you our experiences and you tell yours. I could care less what everyone else does, we saw a trend and solved the problem with a plate...same for the block. Fact is that 90% of shops don't use the plate on these motors and their customers are doing fine and don't know the difference. We feel differently and this is our solution.
Sorry for hijacking the thread. How about back to the new motor
Lets flow this sucker! I have lots of heads to flow against it.
Last edited by DRAG; Feb 15, 2008 at 08:58 AM.
Feb 15, 2008, 11:55 PM
#24
awesome info martin-
are the valve centers the same between the evo 8 to 10 head? did they move the intakes closer to the center, so the larger valves arent shrouded by the bore?
are stem diameters smaller too on the x valves?
are the valve centers the same between the evo 8 to 10 head? did they move the intakes closer to the center, so the larger valves arent shrouded by the bore?
are stem diameters smaller too on the x valves?
Last edited by Aby@MIL.SPEC; Feb 16, 2008 at 01:22 AM.
Feb 16, 2008, 04:19 PM
#25
Hmm, I really want to see flow comparisons between the 4b11 and 4g63 now more than ever. It will either shut up the x fanboys, or shut up the 9 fanboys. Either way, one group will have less to whine about, and the other will have more.
