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My snail is bigger!
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Discussion Starter #1
To those who have had their SOHC heads ported:

So I've taken on the task of porting and polishing my heads... a bit of a DIY job. The intake side is a no-brainer, but I'm wondering about the exhaust side. What I've done on my one of my junk heads is gasket matched the exhaust port. This opens it up quite a bit, but I'm just wondering if it's too much, even for a turbo appication.






Should I reduce the size of the exhaust ports relative to that one when I go to do my actual heads or do you think I'm perfect with gasket matching them?
 

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You need to know the difference between volume and velocity. Many people make the mistake of hogging out their ports thinking that this will lead to an increase in power. It is extremely FALSE. You are looking for a higher velocity which in turn increases flow. You should concentrate on the following areas:

#1 and most important! VALVE JOB. A proper valve job can pick up over 30% in flow if done correctly.

Bowl area.

Combustion area, unshroud the valves and clean up any casting defects.

For the ports themselves, do not worry about enlarging them. Remove the casting marks and make them smooth. Smooth surfaces = better flow w/ less disruption of the flow of the gases rushing past them.

DO NOT KNIFE EDGE YOUR EXHAUST PORT DIVIDER. If you knife edge it, it will eventually deteriorate and break apart.
 

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My snail is bigger!
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Discussion Starter #3 (Edited)
I expected a lot better advice from you... no need to talk down to me. I understand flow dynamics a lot better than your average shadetree mechanic. I have my bachelor's, I have a full-time technical job, this is my hobby. These heads already have a 3-angle valve job. My goal is to approach the same exhaust flow characteristics as the 3S DOHC heads. The exhaust ports are tiny on these heads, there must be some potential gain from enlarging the openings. And that's not knife-edged, it's merely smoothed. No different than the photos of 3SX's ported/polished heads I've been using as an example.

Like I said before, this is for a pretty hefty turbo setup (relative to what anybody else has ever done). If you'd take the time to actually look at what I'm trying to accomplish (500+ WHP) before giving me advice, it may help. There's no way you're going to make 500 WHP on the stock exhaust ports. They're TINY compared to the 3S DOHC heads.

Anybody else?
 

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My snail is bigger!
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Discussion Starter #4
Here is what I'm talking about with the 3S DOHC exhaust ports:

http://www.3sx.com/store/catalog/heads-3sx-port-polish-valves-springs-17-300.jpg

and the exhaust runners are a whopping 5mm wider (stock measures 50mm, these measure 55mm) and 3mm taller (stock 31mm, ported 34mm).
And they're doing that to exhaust ports that all ALREADY significantly larger than our own. Please explain to me why you think it would be a bad idea to port the SOHC exhaust ports to match the gasket.
 

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I expected a lot better advice from you... no need to talk down to me. I understand flow dynamics a lot better than your average shadetree mechanic.

If you'd take the time to actually look at what I'm trying to accomplish (500+ WHP) before giving me advice, it may help.
First off I wasn't talking down to you. I have no idea what your respective knowledge or skill level is. Do I know you have spent a lot of money on your car? Yes.

500WHP on what kind of dyno? It makes a huge difference because cars that make 500 on our dyno make 600 else where. A car that made 592WHP on someone else's dyno made 480 on ours.

I meant no disrespect by my post. For the most part, 90% of the members of this forum are not technically inclined. My post was not just for you but also for others reading this thread. Your ports are not knife edged. I never said they were. I SIMPLY STATED TO NOT KNIFE EDGE THEM because that is one of the worst mistakes people can do when porting besides hogging out the ports.

Do I know how to obtain better flow out of the 6G72 heads? Why yes I do. Am I going to share all that information, such as the actual angles of the cut for the valve job? Nope sure won't. I'll be releasing built heads for this platform soon so I'm not going to undercut myself like that.

I gave you good general information about how to port these heads. And no, I don't keep up with what hardly ANYONE does on this forum. Why? Because I'm too busy.

whew... this is going to be a hot thread...subscribed
There is no need for this thread to get out of hand. I think there was a simple miscommunication. Not every thread I am involved in has to resort to name calling. :lol:
 

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stupid booster
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First off I wasn't talking down to you. I have no idea what your respective knowledge or skill level is. Do I know you have spent a lot of money on your car? Yes.

500WHP on what kind of dyno? It makes a huge difference because cars that make 500 on our dyno make 600 else where. A car that made 592WHP on someone else's dyno made 480 on ours.

I meant no disrespect by my post. For the most part, 90% of the members of this forum are not technically inclined. My post was not just for you but also for others reading this thread. Your ports are not knife edged. I never said they were. I SIMPLY STATED TO NOT KNIFE EDGE THEM because that is one of the worst mistakes people can do when porting besides hogging out the ports.

Do I know how to obtain better flow out of the 6G72 heads? Why yes I do. Am I going to share all that information, such as the actual angles of the cut for the valve job? Nope sure won't. I'll be releasing built heads for this platform soon so I'm not going to undercut myself like that.

I gave you good general information about how to port these heads. And no, I don't keep up with what hardly ANYONE does on this forum. Why? Because I'm too busy.



There is no need for this thread to get out of hand. I think there was a simple miscommunication. Not every thread I am involved in has to resort to name calling. :lol:
yes it does. Give us your knowledge ................................. ASSHOLE :wavey:
 

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My snail is bigger!
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Discussion Starter #9
I'm porting my own heads on an engine I've built myself from the ground up... you can assume I know what I'm doing.

And for dyno numbers... Well, you can expect me to put down 450-475 WHP at 4400' uncorrected on a DYNO-mite dyno that reads about the same after corrections as a Dynapak at sea level. It's pretty consistent. I'm not about BS-ing numbers. She put down 374 on a conservative tune when I was stage 3 SDS with custom ignition,blah blah blah.

I'm going to try gasket matching these heads to the exhaust side. I'm going to closely look at the cross sectional area of the 3SX ported heads and try to accomplish my own variation on my own. We'll see how it goes. I do know I will lose low end, but it will definitely make up for it on the top end. Remember, I'm just opening up the port entrance and tapering it down over an inch.
 

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Just because you build your own engines doesn't mean you know what you are doing. The first engine I built 10 years ago ... God how I screwed that one up. It actually still runs but I had someone give me a hand and we basically had to redo EVERYTHING as I was putting lube on the back side of bearings etc. :lol:

Today... I don't think there is any doubt I can build an engine. My best one so far is a 2.1L that has made 660AWHP w/ a touch of C16 in the mix and 633AWHP on pump gas.

Warm&SCSI... I don't know you and you haven't proven anything to me so I'm not going to assume anything about your skill level hence my previous post. For the future, I will remember that you are above average compared to the rest of the 3G population.
 

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Do I know how to obtain better flow out of the 6G72 heads? Why yes I do. Am I going to share all that information, such as the actual angles of the cut for the valve job? Nope sure won't. I'll be releasing built heads for this platform soon so I'm not going to undercut myself like that.
How soon? Are you using a flow bench? If so can you post gains in CFM? Are you using bigger valves. What is the ball park pricing? Are you accepting cores? Would you like a core for prototype testing asap. I could jump on this so fast right now but it is going to be 6 months from now then forget it.
 

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My snail is bigger!
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Discussion Starter #13
Just because you build your own engines doesn't mean you know what you are doing. The first engine I built 10 years ago ... God how I screwed that one up. It actually still runs but I had someone give me a hand and we basically had to redo EVERYTHING as I was putting lube on the back side of bearings etc. :lol:

Today... I don't think there is any doubt I can build an engine. My best one so far is a 2.1L that has made 660AWHP w/ a touch of C16 in the mix and 633AWHP on pump gas.

Warm&SCSI... I don't know you and you haven't proven anything to me so I'm not going to assume anything about your skill level hence my previous post. For the future, I will remember that you are above average compared to the rest of the 3G population.
I've actually bought stuff from you personally, so whatever.

But thanks for all of the AWESOME advice. God this forum is useless with all of this fucking bickering. Closest analogue I can think of for Club3G is a middle school playground, but whatever. Went off on my own and came up with the following conclusion. I hope this helps anybody who is actually looking to improve upon the flow characteristics of these heads:
WarmAndSCSI said:
Well that solves that mystery. General rule of thumb is that you need about 2 mm of lip between the exhaust manifold and exhaust port to prevent exhaust gas reversion. Stock manifolds are 42 mm in diameter, stock exhaust ports are 38 mm in diameter. There's your 2 mm of lip right there. Question is should I port the exhaust manifolds to match the slightly larger 46 mm gasket at the same time? That would let me safely increase the exhaust port opening to 42 mm, which is still 4 mm over stock!

What's nice is I have a 42 mm exhaust gasket to scribe the head with as well as a 46 mm gasket to do the exhaust manifolds. I think this is the plan.
 

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My snail is bigger!
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Discussion Starter #15
Is this why this is the second engine you blew up??
:rolleyes:

Before I'm done.

No, it's because the machine shop I decided to use this time screwed me. Wasn't told critical information about what had been done to my crankshaft and it ended up destroying another engine. You can go read the horror stories about turned cranks on 3SI if you wish, but had I known pin #3 had been welded to bring it back into spec, I would have never used that crank in my engine. Of course, you have no fucking clue what I'm even talking about, so it doesn't matter.
 

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GSXR PM Pharm about that dont hijack this thread with questions like that. :rant:
Sorry. I was trying to get back to cyilnder heads instead of who has the bigger torque wrench. It is not like the topic is discussed here much if ever and now that it is it is already a pissing match.
 

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My snail is bigger!
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Discussion Starter #17
Sorry. I was trying to get back to cyilnder heads instead of who has the bigger torque wrench. It is not like the topic is discussed here much if ever and now that it is it is already a pissing match.
The topic is exhaust port sizing. I don't know if you missed that. Fucking worthless :rolleyes:

I give up. I already have my answer. Enjoy your fun kids :wavey:
 

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Your right, this thread went to shit in the 3rd post when you got your feelings hurt about what Pharm posted (which was not bad). Pharm is one of the few and only guys on here I would listen to when it comes to stuff like this about our heads and you told him off as soon as you got the chance.
 

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Suk me balls
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:rolleyes:

Before I'm done.

No, it's because the machine shop I decided to use this time screwed me. Wasn't told critical information about what had been done to my crankshaft and it ended up destroying another engine. You can go read the horror stories about turned cranks on 3SI if you wish, but had I known pin #3 had been welded to bring it back into spec, I would have never used that crank in my engine. Of course, you have no fucking clue what I'm even talking about, so it doesn't matter.
:crying: Keep the crying and whining over there at GF dude, seriously!!
 

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Discussion Starter #20
How is sharing some unique information with these SOBs over here crying and whining? DO NOT HAVE 6G72 CRANKSHAFTS TURNED OR WELDED. EVER.

God I swear this forum is the largest group of keyboard warriors and douchebags I've ever seen in my entire life.

I didn't get my feeling hurt by Greg. I got minorly pissed because he wasted his time typing out a bunch of shit I already knew and didn't really answer my question. Get your fucking facts straight. I guess it's kind of hard since not a single person who has posted in this thread minus Greg knows what the fuck we're even talking about. Most of you have about a snowball's chance in hell with actually wrapping your heads around these concepts. Piss off, I'm done here.

And if Greg is the BEST you guys have to offer, then definitely fuck this forum. I know more knowledgeable and experienced people in real life.
 
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