Guest JAMIE T Posted March 17, 2005 Share Posted March 17, 2005 modified chamber stock chamber ported exhuast port The first pic is the chamber modified. The intake side quench pad is removed and the valve seats are blended into the chamber. The exhaust side quench pad is rounded to prevent detonation due to edges in the chamber. The same thing should be done to piston tops, and that includes any high end forging. Even JE doesn't remove the sharp edges on the valve pockets. The head isn't done yet and the first set of ports and chamber probably has more than 8 working hours in it. Quote Link to comment Share on other sites More sharing options...
Synlubes Posted March 17, 2005 Share Posted March 17, 2005 Ambitious project there Jamie. Lets see 8 hrs x 6 ports = 48 + 6 more ports = . . . Nice looking job! After the last L series head I did, I said never again. But, I will also be "cleaning up" my N42 before it goes back together. You going to bring the head up to Mike`s? I wanta see! Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 17, 2005 Share Posted March 17, 2005 Did you get it flowed beforehand? Getting it flowed afterwards? Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted March 17, 2005 Share Posted March 17, 2005 Since each port is the same in shape/length, etc..., I think I'm going to get one set of ports flowed before I port it. Then compare the one that's done to the stock one. Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 17, 2005 Share Posted March 17, 2005 good idea. The issue is unless you have many years of experience porting heads, just going in and doing things to the port that you might think will help may not provide the returns in flow you desire, provide little improvement, or provide improvement at some lifts and not others. Here's an idea: Hegelson (sp?) makes 2-dimensional templates for porting production SBC heads that the novice can use to get things like short side radius, etc. in a good ballpark of what's important as far as changes to make and for checking. I've seen these talked about in David Vizards book on porting SBC heads, if you want further info. If you find your porting is advantageous after the before/after testing, you could use a similar method of making some templates so that you could get close to duplicating the porting in the other ports. The key would be where make the templates (where in the port are the changes you've made most advantageous). BTW, I', wondering if making the center wall beginning very sharp would help things. Quote Link to comment Share on other sites More sharing options...
ZROSSA Posted March 17, 2005 Share Posted March 17, 2005 Jamie, Go have a play around http://www.theoldone.com Study all the 4 valve heads you can. I think you will find that you will want to keep the quench pads, particularly the intake side, so that the combustion chamber has a bias towards the exhuast valves. Get your chamber right and you can run lots of compression with a turbo. Douglas Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted March 17, 2005 Share Posted March 17, 2005 Removing the quench pad on the intake side was under advise from Matt Hutchins who builds alot of high powered RB26's. His detail and knowledge of the subject is great how he described each item and potential problem and cause and effect. Pete, i've got a fair amount of experiance porting and polishing heads. Probably more than a dozen sets of SBC, SBF, 4.3L GM, BBC, etc... This IS my first DOHC head. I've not changed the shape of the port in any significant manner. The main work is in the bowl and the chamber. Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 17, 2005 Share Posted March 17, 2005 Jamie, this isn't a slam. You may well have done testing on your work, but unless you've done before/after flow, dyno runs, and/or drag runs under controlled conditions on your porting work, how do you know if those heads were any better performance wise when you were done? Quote Link to comment Share on other sites More sharing options...
cheftrd Posted March 17, 2005 Share Posted March 17, 2005 Jamie, this isn't a slam. You may well have done testing on your work, but unless you've done before/after flow, dyno runs, and/or drag runs under controlled conditions on your porting work, how do you know if those heads were any better performance wise when you were done? Because the RB26 has been done over and over and over again. HKS is the only one who still retains some "secret" info for keeping the head in place. The limiting factor on the RB26 is the head lifting at around 1200-1300hp. It will pull the bolts right out of the block, stripping the threads. Larger bolts will crack the cylinder between the bolt hole and cylinder. With the exception of how HKS keeps the head on their engine, there is no new development to be done for this engine. This is why I hate building this engine.....it's BORING. There is no new R&D to be done. BTW, I suspect that HKS uses much larger studs and installs thick sleeves, in addition to a partial filling of the block. Head modifications are well documented. What Jamie has done is right in line with the Nismo GT500 circuit race engines. This info is even published. The port shape does not change. Smooth the bowl and short-side radius, knife edge the splitter, push the splitter back about 1 cm into a "V" in higher rpm engines. Exhaust side gets the "lump" removed and the bowl and short-side radius cleaned up. Knife edging the splitter in the exhaust port will give very small returns. Both ports can be manifold matched and the valve guide boss' gets smoothed into a "V". Remove the intake squish pad and chamfer the exhaust. These are the basic head mods that every tuner in Japan does. The pads in the combustion chamber are not quench pads designed for inert effects, like an OHV American V8. They are squish areas to promote chamber turbulance and a faster burn at lower engine speeds. Mid level engines have the intake side removed and the exhaust side chamfered. Full race engines have both pads removed (the Pulsar GTI-R SR20 chamber is like this from the factory). Removing the pad on the intake side has two effects, besides lowering compression, it unshrouds the intake valves for a substantial power increase and eliminates pocket detonation. Without this mod, you will burn the pistons on the intake side when getting near 600hp. You will not hear the detonation, but it's there. A knock meter won't pick it up in a 700 hp engine because mechanical noise is substantial. Quote Link to comment Share on other sites More sharing options...
ZROSSA Posted March 18, 2005 Share Posted March 18, 2005 Didnt mean to point anyone in the wrong direction. I guess there is a point where boost takes over from mechanical compression. Still you need the combustion chamber to burn properly, no mater what the engine. Have a look around that site James. Interesting reading. Douglas Quote Link to comment Share on other sites More sharing options...
cheftrd Posted March 18, 2005 Share Posted March 18, 2005 Didnt mean to point anyone in the wrong direction. I guess there is a point where boost takes over from mechanical compression. Still you need the combustion chamber to burn properly' date=' no mater what the engine. Have a look around that site James. Interesting reading. Douglas[/quote'] You're not pointing anyone in the wrong direction. For the most part, pent roof combustion chamber theory follows true. When I first started messing with the 26, I thought the people performing this mod were full of it too. I was like "watch this; I'll show these Japanese guys what thinking outside the box is all about". A few burnt down RB26's later.......... It's a sacrifice made in high power boosted engines. You sacrifice some combustion efficency for the ability to run more cylinder pressure and make more power. The off-boost power loss is not really noticable, though. Being from NZ you probably know that 600-700 hp GT-R's are a dime a dozen running around the streets of Japan. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted March 18, 2005 Share Posted March 18, 2005 Here is a pic of a 26 head where the removal of the pad may have helped this motor live longer.... Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 18, 2005 Share Posted March 18, 2005 Because the RB26 has been done over and over and over again. HKS is the only one who still retains some "secret" info for keeping the head in place. Very nice to hear. Is this info on head mods thoroughly documented somewhere, with testing what works and what isn't worth while to do as far as mods? Still, even though it may be that mods to the head is well documented on how to get increases from head porting, minor details in how the valve job is done can make vast differences in flow, and hopefully power production. Pete Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted March 18, 2005 Share Posted March 18, 2005 Thanks Matt for helping me with the project. I have the head at the guys shop who will flow the ports. He is VERY knowledgable and I trust the hell out of him. He's done AMAZING work. He approved of what I'd done but of course had never heard of a Nissan Skyline GT-R. He wasn't sure why the lump in the exhuast port was there, and figured Nissan changed there mind on the bolt hole location that is near by. He approved of my short side radius work on the intake and actually muttered "impressive"... He is going to do the valve job and deck it when I'm done porting it. He is the finest cylinder head guy in my area. He did mention some stuff that would be awesome to do on a future head. He suggested raising the exuast port by atleast a 1/4". To make the path straighter. He also said the Turbo engines like to have a tight exuast port to keep velocity up. I opened up my ports to the stock gasket, but no further. I might go way out on the head on my engine after I swap this head on to it. I'll raise the intake and exhuast port ports by adding weld to the port floor and on top of the port and re shaping the port completely. I'm also going to build my own flow bench for future use. Pete, I've ported alot of heads and have proven performance with them. My SBF ported stock 5.0 heads out flow and way out-perform Edelbrock heads. I did a set for a guy that included machining for bigger valves, etc... They were nice. He was dissapointed in his cars performance and TRADED a guy the heads I'd done for a set of Edelbrock Performer heads and his car lost 3 mph in the 1/4. And, the other guys car got faster. The heads on my Z28 are freakin works of art in the bowls and chamber. Shear horse power and torque curves have allowed me to be confidant in my abilities. I don't use "plugs" or templates to check the ports. I use inside calipers and dial calipers to check progress as I go. Taking my time to sculp each port. I leave the valve job to my head guy. I'm 29 years old and have been doing this work since I was 14. Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 18, 2005 Share Posted March 18, 2005 Jamie, nice to hear that you do the testing on your work and use precision methods for doing the work! So many times I see people either buy heads and believe that they are bolting on a potential for power or others that just pull out the grinder without ever testing their work on a flow bench or dyno. (e.g., See the threads about Canfield heads that vendors supply with their own lousy valve work that make them flow much worse than they would if bought directly from Canfield already assembled.) All that needs to happen is for my old Eclipse to bite the dust and I'd be buying that Z/28!!! In other words, I'm not doubting your expertise! Oh, building the RB26 might be boring to some, but I don't think 600-700 hp would be boring to me!! Cheers, Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 18, 2005 Share Posted March 18, 2005 I gotta agree with Jamie on this one. Pete, I think you're right that people can screw up a head, but if you look at what others have done right, don't try to reinvent the wheel, and don't go crazy with the grinder you won't be disappointed IME. I've just ported a couple of heads now, never flow tested any of them, but they certainly seemed more powerful when I was done. One, my Toyota 22re, with no other changes idled 2000 rpm higher when I fired it up and ran it again. Nissan, GM, Ford, doesn't matter who but ANY mass producer of vehicles isn't going to leave the chambers all exactly the same size, nor are the castings going to be perfect. There is room for improvement on just about anything coming out of a factory. Interesting stuff about the quench pads. I wouldn't have thought that they would be a source of detonation, but then I suppose when you run very high psi through on a turbo setup the rules of the game are bound to change. Quote Link to comment Share on other sites More sharing options...
cheftrd Posted March 18, 2005 Share Posted March 18, 2005 Oh' date=' building the RB26 might be boring to some, but I don't think 600-700 hp would be boring to me!! Cheers,[/quote'] The power's not boring. I'm just one of those people who thrives on going places others haven't. That's why I started doing swaps with the 26. The RB26 is a fantastic motor and can take an old Z car to places where the L motor doesn't even dare to dream. Reliably! I never even work on GT-R's anymore Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted March 18, 2005 Share Posted March 18, 2005 Pete, this is the first head I've ever had flow tested. My head guy agrees that you can't argue with success. I decided it would be best for this head since in the US, we seem to know little about it. Since I have a couple of them, I figure I should learn first hand what works and what doesn't. That way when the engine gets more popular and more of them are brought here, those folks will have a place to turn for honest performance information. I'm dead serious about performance and take pride in my craft, whatever it may be. My head guy said his valve job will yield huge improvements. I'm getting the head flowed before and after the valve job also. Great pic Joel! Is that head off the same motor that the crank with the worn oil pump lobe came out of? I don't think I'll be bored with 600-700hp either Pete. BTW, don't you have a nice Zcar that you'd trade for my Z28? Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted March 18, 2005 Share Posted March 18, 2005 Great pic Joel! Is that head off the same motor that the crank with the worn oil pump lobe came out of? Yep Jamie, thats the one. That motor died a horrible death, that wasn't only caused by detonation. It was beat down to the ground in every possible way.. I just may remove my head once I get the car back from James, and finish off my head work by removing the intake pad. Thats the only thing I did not do... Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 18, 2005 Share Posted March 18, 2005 Pete, this is the first head I've ever had flow tested. My head guy agrees that you can't argue with success. I decided it would be best for this head since in the US, we seem to know little about it. Since I have a couple of them, I figure I should learn first hand what works and what doesn't. That way when the engine gets more popular and more of them are brought here, those folks will have a place to turn for honest performance information. I'm dead serious about performance and take pride in my craft, whatever it may be. Flow isn't the whole story, as we all know. But dyno and drag strip performance is the bottom line (if you can keep the changes in all the other variables the same). My head guy said his valve job will yield huge improvements. I'm getting the head flowed before and after the valve job also. That's a great idea. First the before/after porting flow numbers, then the before/after valve work numbers. Some people don't understand just how important the valve work is to good flow. You'll have the data to show your port work improvements, and your specialist's valve work improvements. Write up a web page on it!!! I don't think I'll be bored with 600-700hp either Pete. BTW, don't you have a nice Zcar that you'd trade for my Z28? You are so funny. Your Z28 is faster than my 240Z, but I think I'll keep my 240Z. I want your Z28 in ADDITION to my 240Z . But you knew that! Quote Link to comment Share on other sites More sharing options...
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