Mudge Posted August 1, 2003 Share Posted August 1, 2003 OK, here is what I am proposing for the combustion chamber mods. That is not a P90 head right? It looks open chamber to me? Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted August 1, 2003 Author Share Posted August 1, 2003 It is indeed a P90 head. All mods to the chamber will be done by welding material and then removing it to the new desired shape. I am going to do one cylinder on this junk head and have it flowed. I hope I can have it modded by the end of next week so I can slap it onto a flow bench. If 250cfm is realized below .600" lift then.... In the how to hotrod book they have flow #'s for an early 260Z head. It made 238cfm at .500" lift and 251cfm at .600" lift. I will probably run the Web .585" cam on this next head. Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted August 1, 2003 Share Posted August 1, 2003 Big flow = Big cam Was I right about the 290cfm being at .600" lift? Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted August 1, 2003 Share Posted August 1, 2003 This is looking very promising James. We appreciate your intrest in making the L6 head work better for us strait 6 guys.. Although they are not the P90 head, I have a stack of every other # head, if you need to chop up another. Also, please keep me in mind when you upgrade your cam, I'd buy your current one from you. thanks and keep it up... Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted August 1, 2003 Share Posted August 1, 2003 James, I'm sure you've seen the E31 head pictured on page 47 of the How to modify book. Those ports look pretty large I looked at a FIA group 2(4 cyl L4) head awhile back. That thing had huge ports almost 2" diameter. They would have been fed by 50MM mikuni's. It actually seems like the raised area between the valves would hurt flow. But. I'm not sure about that. The only reason I could see doing it would be to increase compression. I could be wrong on that though. I thought the P90 was supposed to have superior chambers over other L6 heads anyway? Maybe do one with just unshrouding the valves. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 1, 2003 Share Posted August 1, 2003 heck I won't even be greedy, 250 cfm works for me. Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted August 2, 2003 Share Posted August 2, 2003 Awesome discussion here, this is what this board is all about. I honestly believe this is one of the best discussion boards on all the net. Nice tight-knit community of rebels with ideas and engineering degrees to back them up 8) I want to see what will happen with this P90. I've been scouring the board for all the info I can find because I think I see an L28ET buildup in the future for me... Quote Link to comment Share on other sites More sharing options...
speeder Posted August 2, 2003 Share Posted August 2, 2003 I've been lurking on this discussion with great interest since it started. James, You da man! After you do all the hard research work I'm ready to start on my own P90! I've got to second that Hybrid Z is the BEST gearhead's resource I've ever encountered. Quote Link to comment Share on other sites More sharing options...
niceguy678us Posted August 3, 2003 Share Posted August 3, 2003 You guys always get a two thumbs up from my corner !! I have come to rely on this board verses any other on the internet. I can't wait to see how this P90 head modification comes out!! Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted August 3, 2003 Author Share Posted August 3, 2003 I just want to spark some interest and in the process learn something. I checked out a book today from the library entitled, "The theory and practice of cylinder head modification" by David Vizard. This was recommended to me by the fellow who is an expert on cylinder heads. I would advise you read this if you can find it. However, I need to find if any differences in the designs of port and combustion chambers will be necessary when turbocharging is considered. This book details how to mod the combustion chamber, how to design a port for maximum flow. How increasing the valve size can decrease flow if there is increased valve shrouding. What is the optimal port size based on the valve Diameter. Anyway, this is very exciting stuff to me and the thought of making 250+cfm from these ports is worth the time/money. Now...can someone donate some money to me? Actually, this guy is willing to develop a port on this scrap head to test the possibilities. This includes the modifications to the combustion chamber. He said he would not rake me over the coals, but it will cost a few hundred bucks. WEll, I will keep you posted on the progress. Quote Link to comment Share on other sites More sharing options...
jeffp Posted August 3, 2003 Share Posted August 3, 2003 I dont think the raised part of the chamber in between the valves is going to beneficial. What I would do in stead is to relieve the block and the head like you see on big block chevy engines on the exhaust side. Using a metal head gasket will enable you to open up the exhuast valve flow on the edge of the combustion chamber, then cutting a slight relief in the cylinder, and deck to mirror the relief in the head will improve the flow significantly, then with the other modifications to the port you should reach the numbers you are looking for. The intake side of the head is easily improved with your porting, then use a stainless steel valve that is worked with the valve seat area close to the top of the valve head, remove excess valve area by countouring the valve to a smooth transition to the seat on the valve. That will improve the flow of the intake valve. Now, the lift on the cam, you will want to watch the lift on the exhaust side as increased lift on a ported head tends to hinder flow, but with a good relief in the side of the combustion chamber it may improve. The trick here is to use the valve and the lift to promote an easy exit of the gases, with the relief in the head and the deck, you can use the valve as a base for the exit, then contour the port, to flow with the added opening in the combustion chamber and deck. Do you see what I am talking about? anyway just some of my thoughts. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted August 3, 2003 Author Share Posted August 3, 2003 I was told the ridge between the valves does, in fact, help performance. It is said to help direct charge and also hinder the ability to flow out the exhaust during valve overlap. The combustion chamber is critical to power for several reasons: 1) unshrouding of the valve to help increase flow 2) directing the charge towards the center of the bore 3) swirling of the charge to help promote a better burn these can all be very significant in making power. I don't claim to understand the dynamics of this event as it relates to reshaping of a chamber. However, the important thing to realize is this has a significant affect on power. BTW, someone posted a pic of the Maxima N47 combustion chambers. Very interesting...heart shaped chamber...small cc....looks promising....me likes! Quote Link to comment Share on other sites More sharing options...
Bluto Posted August 13, 2003 Share Posted August 13, 2003 Had to make sure this post didnt get lost in the merge.. hate to see it lost! btw, any updates? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 13, 2003 Share Posted August 13, 2003 I think you're right about the ridge hindering overlap. I cut the ridge way down to get more effective overlap on my NA motor at the suggestion of my machinist (who builds lots of race engines). Jon Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted August 14, 2003 Share Posted August 14, 2003 Couldn't the "ridge" between intake and exhaust result in a "hot spot" where pre-ignition could occur? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 14, 2003 Share Posted August 14, 2003 Depends on how thin you make it. I'm sure if you made it razor sharp there would be issues. Jon Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted August 15, 2003 Author Share Posted August 15, 2003 Update: The head is with the machinist who agreed to develope one intake/exhaust port on the chopped up head at a very good price. He will use epoxy instead of welding because it is just prototyping work. The price was good because he appreciated the head being chopped in all directions to take the guess work out of porting. He had many heads to show me at his shop and how modifying the chambers directly influences port flow and swirl. Interesting stuff to say the least. One of the mods he will be doing is to angle the spark plug towards the exhaust valve. I was shown a Busch series head and they only flowed in the 380+cfm range on the intake ports! I also checked out some top fuel heads...no wonder they flow so well! Heads with dual plug'd hemispherical chambers and much more. Anyway, he has a SuperFlow 600 with velocity probe and swirl meter. I should know something within 2 weeks time. Will keep you posted! Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 15, 2003 Share Posted August 15, 2003 Sweet stuff James, keep it coming! Quote Link to comment Share on other sites More sharing options...
clint78z Posted August 15, 2003 Share Posted August 15, 2003 I found this website a while back not sure if I posted it. It has some great info if you start digging. The company has an impressive track record with NHRA Bob Glidden mop the track with his engines . The one thing that impresses me is that everything is not a huge secret. Obviously they have trade secrects, but they explain all their concepts. This one is good reading for ford, chev, hell any gear head. http://www.theoldone.com/about/default.asp Quote Link to comment Share on other sites More sharing options...
turbobluestreak Posted August 26, 2003 Share Posted August 26, 2003 Any updates on the head yet? Also when we get the results can we see it on a data sheet? tbs Quote Link to comment Share on other sites More sharing options...
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