New record for pump gas, set with the HTA35r
Nov 14, 2007, 12:12 PM
#91
Dave,
First off thanks for the in-depth explanation you posted..........as i know you do not have to share your hard learned information with the rest of us
Very interesting to hear what you have to say in regards to head porting and cam selection.
FWIW - I too disagree w/ the statement about the Mustang vs DynoDynamic dynos as we have had cars that had testing done on our Mustang and another shops DynoDynamic and ours was about 25-30 hp less.
My ? is how does all of this change if any when speaking in terms of an Evo9 w/ Mivec
Have you guys any experience w/ building a car w/ similar mods BUT w/o porting the head........as it seems to me that this is where a lot of power is made as you stated.
I'm currently waiting to install the 2nd fp and wil try and run the boost up as high as possible but just wondering if we'll hit a wall in terms of hp w/o the head being ported.
First off thanks for the in-depth explanation you posted..........as i know you do not have to share your hard learned information with the rest of us
Very interesting to hear what you have to say in regards to head porting and cam selection.
FWIW - I too disagree w/ the statement about the Mustang vs DynoDynamic dynos as we have had cars that had testing done on our Mustang and another shops DynoDynamic and ours was about 25-30 hp less.
My ? is how does all of this change if any when speaking in terms of an Evo9 w/ Mivec
Have you guys any experience w/ building a car w/ similar mods BUT w/o porting the head........as it seems to me that this is where a lot of power is made as you stated.
I'm currently waiting to install the 2nd fp and wil try and run the boost up as high as possible but just wondering if we'll hit a wall in terms of hp w/o the head being ported.
Nov 14, 2007, 12:33 PM
#95
The ports on 1G DSM heads are larger than the ports in an EVO head, and even when both are ported, the 1G still flows a little higher. Here's a comparison from Fox Lake, who builds CNC'd cylinder heads that John Shepherd uses: http://www.foxlakeracing.com/shep.php
Compared to stock, a well ported cylinder head will pick up 50-65 CFM and still have good port velocity.
Compared to stock, a well ported cylinder head will pick up 50-65 CFM and still have good port velocity.
Nov 14, 2007, 02:16 PM
#98
I have flow tested a lot of cylinder heads here from other companies. I have kept notes from all of them that we have tested and the flow charts.
There are many companies making BS claims as to high their heads flow and other companies that are porting them and the heads loose flow everywhere but up and over .400 lift, which is retarded as there aren't many cams that go much over .400 lift in the first place. Then these companies advertise they gained XX% on their port work, problem is that gain is at .500 lift and it is useless.
We did back to back testing from non ported to ported heads. When we did it we did it on small turbos, maybe stock actually, been 3 years and I don't remember. I say if you are sticking with the stock turbo or probably even the Green, porting of the head is going to gain you very little in power.
There are many companies making BS claims as to high their heads flow and other companies that are porting them and the heads loose flow everywhere but up and over .400 lift, which is retarded as there aren't many cams that go much over .400 lift in the first place. Then these companies advertise they gained XX% on their port work, problem is that gain is at .500 lift and it is useless.
We did back to back testing from non ported to ported heads. When we did it we did it on small turbos, maybe stock actually, been 3 years and I don't remember. I say if you are sticking with the stock turbo or probably even the Green, porting of the head is going to gain you very little in power.
Nov 14, 2007, 03:36 PM
#99
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I would like to ask Dave B If what I read in Turbo is true about your guys stage 3 head that uses .5mm oversize valves? it seems most shops use 1mm over. Is this to avoid peaky power and obtain a good curve while improving flow or is this a typo? Thanks!
I also remember years and years ago the Extremes old race/ported heads only used oversive valves on the exhaust side regardless if a 1g or 2g and there were no Evos.
Nov 14, 2007, 03:47 PM
#101
I will say as already said that 1G heads have larger intake ports then 2gs and Evos. I have a mildly ported head from a local machine shop that seems very knowledgable. He (the owner) said that 1g heads intake ports should only be deburred/smoothed. All the porting should be focused in the bowls and exhaust side. If you get aggressive with the intake side you actually lose power execpt peak HP. He also noted 2gs and EVO heads take well to only mild porting on the intake side.
I would like to ask Dave B If what I read in Turbo is true about your guys stage 3 head that uses .5mm oversize valves? it seems most shops use 1mm over. Is this to avoid peaky power and obtain a good curve while improving flow or is this a typo? Thanks!
I also remember years and years ago the Extremes old race/ported heads only used oversive valves on the exhaust side regardless if a 1g or 2g and there were no Evos.
I would like to ask Dave B If what I read in Turbo is true about your guys stage 3 head that uses .5mm oversize valves? it seems most shops use 1mm over. Is this to avoid peaky power and obtain a good curve while improving flow or is this a typo? Thanks!
I also remember years and years ago the Extremes old race/ported heads only used oversive valves on the exhaust side regardless if a 1g or 2g and there were no Evos.
Nov 14, 2007, 04:12 PM
#103
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Im sorry I was trying to point you out with what you said. I just used your quote because the unported DSM head phrase. I do agree with what you said. I just dont think most Evo owners know the difference in size from a 1g port to an Evo port. Extremely different. I have seen some flow bench numbers that say that 1g head floe better then 2gs stock by a good amount. then take that same head and having it ported with stock size valves then outperform the 1g head.
Nov 14, 2007, 07:24 PM
#104
Get the air in and back out as easily as possible. I'd venture to guess I could run a GT42R on this same car at 40 psi of boost on 93 octane without a problem. The reason is the compressor wheel is efficient, keeps the charge air temps cool and the exhaust wheel keeps back pressure down which keeps the cylinders free of the old backed up exhaust from the last event.
Dave I'm going to hold you to this comment next year!LOL
Dave I'm going to hold you to this comment next year!LOL