josh817 Posted February 27, 2009 Share Posted February 27, 2009 I'm at a cross roads... college is coming up in a couple of months, money is flowing, my head may not be flowing, spend $1500 on a port job? I ported and polished my head myself, however it was my first head so I have no idea what I was doing really besides the basics. Now I'm worried that I'm only feeling like 200hp rather than maybe uhhhh 260ish? The things I am considering is that I can sell off my head since it has a Schneider cam and I can call my port job mild, P90A solid lifter conversion. I am also considering that spending big money on a head is a one time thing unless you mess it up somehow. I just can't bring myself to spending that much money that quickly. I'm thinking well... I can just wait until the next motor to put the head on however who knows when that will be. I'd hate to wait until the last leg of my motor to install a new head... Tell me what you guys think of this plan: Dyno day coming up soon, if power is under 220hp, get Rebello head (because I'd hate to make good power and then spend $1500 to make 10 more hp). I think I can safely ask for ehhhh $700-$800 for this P90A head? Not even 2000 miles on it, mild port, unshrouded valves, polished chambers, .495" 290º cam, solid lifters, ready to bolt on. Save me some money there I guess. I don't know. For some reason I had the urge to call them today and now all my plans just got bumped down one spot to make room for a head which I really want but as we all know, its damn expensive. I WOULD sit down and do more work on a head myself however I don't have a flow bench and I think the likeliness of getting 200cfm for the intake and 140cfm for exhaust would be slim with me on a learning curve. Thoughts? EDIT: Forgot one more idea, lets do consider that $1500 all at once is painfull however $2000 over a period of time isn't so bad. We've seen 1 fast Z's DOHC KA head... Maybe with some engineering one could be done... agian. Then I would have uhhhh 300 cfm? Highly unlikely, I would have to get working head gasket unless I can just use a normal Datsun one, then I would have to somehow get my intake/exhaust onto the KA bolt pattern... Then figure out cams, and finally throtle linkage. Hmmmmm.... Quote Link to comment Share on other sites More sharing options...
Challenger Posted February 27, 2009 Share Posted February 27, 2009 I wouldnt count on getting that much for your head. You might but it might take awhile. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted February 27, 2009 Administrators Share Posted February 27, 2009 Lets get your priorities straight first! Quit using flow numbers and power figures as if they are somehow one in the same. I’ve beat this drum before. I can port your head to deliver impressive flow numbers on a bench that will beat lots of other “flow bench” racers numbers, but I guarantee you the head I port for the next guy who wants to build torque and power will out run your "flow bench" special down the drag strip each and every run with better drivability, mileage, power under the curve! Hear me know, believe me later, and think about it sometime. Flow bench figures are NOT HP figures, and vice versa! A flow bench is a tool used by the person porting the head balancing the flow across the cylinders of the head, and those max flow figures are only to help him in becoming more proficient at his craft. For the end user, flow bench numbers only indicate a heads potential to flow statically, not taking into account runner lengths, expanded exhaust gasses, scavenging, valve closures, yadda yadda yadda. It is akin to a torque wrench, i.e. a tool, not a dyno. The torque value on your rod bolts has about as much indication at how much power your engine can produce as flow bench numbers! Dave Rebello is one of the most respected and renowned L-series race engine builders on this planet! He uses the tools he has at his disposal to extract the most power he can, and has proven that time and again at race tracks all over the world with cars running his engines. He uses a Dyno to test and verify his work. He uses a flow bench for repeatability and to enhance flow, then backs up it up on the Dyno. Again, the Dyno and a wining track record are the final say, NOT a flow bench number! Regardless of flow bench numbers, if you want a head that flows with respect to making power, you can have Rebello port your head and you will be rewarded with a cylinder head with not only several years of experience in testing and proving what does and does not work, but also many years worth of race winning, dyno proven power production behind it. Then back up that port work with a tight lash Rebello cam! Trust me when I say the Rebello tight lash cams are incredible! VERY aggressive ramp rates, lots of lift under the curve, delivering a broad powerband! The .520” lift grind is the cam he uses on his 300 HP N/A 3.1 strokers! For a more streetable version of that cam, (I call it the sister cam), the .487” performs comparable to the Schneider .500” lift cams with smoother street manners! Induction must be aftermarket EMS with a custom intake or carbs to realize this sort of N/A power potential. That’s my not so humble opinion. Quote Link to comment Share on other sites More sharing options...
josh817 Posted February 27, 2009 Author Share Posted February 27, 2009 Lets get your priorities straight first! Quit using flow numbers and power figures as if they are somehow one in the same. I’ve beat this drum before. I can port your head to deliver impressive flow numbers on a bench that will beat lots of other “flow bench” racers numbers, but I guarantee you the head I port for the next guy who wants to build torque and power will out run your "flow bench" special down the drag strip each and every run with better drivability, mileage, power under the curve! Hear me know, believe me later, and think about it sometime. Flow bench figures are NOT HP figures, and vice versa! A flow bench is a tool used by the person porting the head balancing the flow across the cylinders of the head, and those max flow figures are only to help him in becoming more proficient at his craft. For the end user, flow bench numbers only indicate a heads potential to flow statically, not taking into account runner lengths, expanded exhaust gasses, scavenging, valve closures, yadda yadda yadda. It is akin to a torque wrench, i.e. a tool, not a dyno. The torque value on your rod bolts has about as much indication at how much power your engine can produce as flow bench numbers! Dave Rebello is one of the most respected and renowned L-series race engine builders on this planet! He uses the tools he has at his disposal to extract the most power he can, and has proven that time and again at race tracks all over the world with cars running his engines. He uses a Dyno to test and verify his work. He uses a flow bench for repeatability and to enhance flow, then backs up it up on the Dyno. Again, the Dyno and a wining track record are the final say, NOT a flow bench number! Regardless of flow bench numbers, if you want a head that flows with respect to making power, you can have Rebello port your head and you will be rewarded with a cylinder head with not only several years of experience in testing and proving what does and does not work, but also many years worth of race winning, dyno proven power production behind it. Then back up that port work with a tight lash Rebello cam! Trust me when I say the Rebello tight lash cams are incredible! VERY aggressive ramp rates, lots of lift under the curve, delivering a broad powerband! The .520” lift grind is the cam he uses on his 300 HP N/A 3.1 strokers! For a more streetable version of that cam, (I call it the sister cam), the .487” performs comparable to the Schneider .500” lift cams with smoother street manners! Induction must be aftermarket EMS with a custom intake or carbs to realize this sort of N/A power potential. That’s my not so humble opinion. Well now not to stir up some trouble. I'm going to give you call and figure out what you can do. Its a split between Rebello, You, or 1 fast z. I know I want his cam, and if I wind up like ZRedBaron I think it was with like a 180hp stroker, well I will be pissed and a new head will be a must while this motor is still fresh. The KA head sounds exciting and it may be a long term project with my spare block, however I think I want to keep the origins of the Z species on my motor. Once you go twin cam I don't see why not go out and buy an RB and put ITB's on it or whatever. Plus it kind of either knocks you out of certain classes for racing or it knocks you up into an unlimited class where you get raped by other fellers. When I called up I asked for race and street port prices however race port probably won't be suitable for me since that flow will only be good for the higher RPM's. $1500 was a quote to have a P90 core street ported and his cam although I think I want a full setup due to (like you said) the nature of his cam and the spring rates involved. If I get a junkyard head, tear it down, have them do their thing and send it back with cam and springs, have rockers sent off for resurfacing and buy some swirl valves I would be good. $700 sounds on the pricey side for the head I have now too. I don't think I would go anything lower than $500 though. The cam setup + good clean head costs more than that, now add the solid conversion (only like $30) and a mild port job. Meh who knows. Everything is up in the air right now. I do know dave Rebello has a very good reputation however he is my goal setter. I'm 18 years old now, have little but SOME interest from others on building their motors. I'm looking to build up a reputation and hell maybe in 10, 20, 30 years I'll be a competitor of Rebello? Just have to keep my nose clean, keep the quality high, and make sure everyone is happy. Personally, I am not particularly fond of outsourcing my motor parts to others. I would much rather prefer to port another head myself but porting and polishing and L series head isn't a shops every day work and I'm not into the business of porting a head without having proof numbers to back my work up. If I can't port a head and send it out with a card showing its specs then I don't want to do it. Simply put, I refuse to port heads for others but I have enough spare time to do one for myself... as you can see I have doubts with the flow of mine though. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 27, 2009 Share Posted February 27, 2009 Why don't you look at making a flowbench? There are lots of plans online. I think Rebello's street port isn't going to be much different than yours if you took your time and did what you did well. At your dyno day keep in mind that you will be measuring whp, Rebello measures bhp. Also different dynos measure differently, so something that was measured on Rebello's dyno might show higher numbers than something measured on a different shop's dyno. In fact if that happened it wouldn't surprise me at all. Katman has talked numerous times about "west coast hp", and Drax240z has said that he can tweak his dyno to measure 100 hp higher or lower at will. Knowing what little I do about your motor, I'd try swapping in a Rebello cam or even better a Sunbelt single valve spring cam before I spent big $$$ on a "street port" job. I don't think the Rebello headwork AND the cam are going to net you 60 whp though. 60 whp is a LOT. If you want big hp numbers out of small displacement motors, you have to increase displacement, increase compression, and spin them faster. All the while your reliability and streetability and longevity is going down. Finally, rather than doing a frankenhead with the cut up KA heads, why not just consider a motor swap or a turbo? You could hit your goals EASILY and not have to put all the time and energy into any of the above. When I realized the time and effort I put into my L28 I finally said screw it and went out and bought a 310hp 5.3L V8 with 27K miles on it for $1100. Sure I'll have a couple grand in a trans, clutch, driveline, and the rest of what is needed to get it running, but it will still be a lot cheaper than the L, and I won't have to run race gas. In fact, I'm betting it will run fine on 87 octane when its all decked out in "race trim". There are tons of other options though from the RBs, to the SRs, to the KA, the 1JZ, 2JZ, 7MGE, and all these engines can easily outdo a built up NA L series without breaking a sweat. Quote Link to comment Share on other sites More sharing options...
X64v Posted February 27, 2009 Share Posted February 27, 2009 ...why not just consider a motor swap or a turbo? That's what I was just thinking. Turbo is the way to go for streetable power on an L6 IMO. I'm at about 240whp (rough estimate) with more than enough torque off boost to feel just fine around town, even at 7.3:1 SCR. And I certainly have less than $1500 in my entire motor, including the engine rebuild, EMS, turbo, etc etc. Quote Link to comment Share on other sites More sharing options...
josh817 Posted February 27, 2009 Author Share Posted February 27, 2009 Why don't you look at making a flowbench? There are lots of plans online. I think Rebello's street port isn't going to be much different than yours if you took your time and did what you did well. At your dyno day keep in mind that you will be measuring whp, Rebello measures bhp. Also different dynos measure differently, so something that was measured on Rebello's dyno might show higher numbers than something measured on a different shop's dyno. In fact if that happened it wouldn't surprise me at all. Katman has talked numerous times about "west coast hp", and Drax240z has said that he can tweak his dyno to measure 100 hp higher or lower at will. Knowing what little I do about your motor, I'd try swapping in a Rebello cam or even better a Sunbelt single valve spring cam before I spent big $$$ on a "street port" job. I don't think the Rebello headwork AND the cam are going to net you 60 whp though. 60 whp is a LOT. If you want big hp numbers out of small displacement motors, you have to increase displacement, increase compression, and spin them faster. All the while your reliability and streetability and longevity is going down. Finally, rather than doing a frankenhead with the cut up KA heads, why not just consider a motor swap or a turbo? You could hit your goals EASILY and not have to put all the time and energy into any of the above. When I realized the time and effort I put into my L28 I finally said screw it and went out and bought a 310hp 5.3L V8 with 27K miles on it for $1100. Sure I'll have a couple grand in a trans, clutch, driveline, and the rest of what is needed to get it running, but it will still be a lot cheaper than the L, and I won't have to run race gas. In fact, I'm betting it will run fine on 87 octane when its all decked out in "race trim". There are tons of other options though from the RBs, to the SRs, to the KA, the 1JZ, 2JZ, 7MGE, and all these engines can easily outdo a built up NA L series without breaking a sweat. Because I have already built a stroker motor and I would like to keep it that way. :] I WOULD do any of the other options however I wanted something unique. My biggest issue was wiring. I can't stand wiring and I don't know ANYTHING about MS or any of that stuff. I am however considering going over to a turbo again. Something small because my comp. is at around 8.5-9:1. I still don't know though, I don't know how much boost or anything. I don't know anything about fuel injection and I already have an EDIS-6 setup however I think MS can run it. Making a high 200hp motor on carbs excites me and thats all I want. I never wanted 300+hp, tires won't hook up, things break, I can't fund that. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 27, 2009 Share Posted February 27, 2009 The stock ports on L6 heads (E88, N42, E31) head flow well enough to generate an honest 200 horsepower using the stock cam, pistons, and SUs. Some work (mostly on the exhaust side) balancing flow, bumping the compression ratio to 12 to 1, and .500 lift 300+ duration cam will get you an honest 240 horsepower - still on SUs. I personally think that $1,500 would be better spent on books and tuition for your college. Quote Link to comment Share on other sites More sharing options...
josh817 Posted February 27, 2009 Author Share Posted February 27, 2009 The stock ports on L6 heads (E88, N42, E31) head flow well enough to generate an honest 200 horsepower using the stock cam, pistons, and SUs. Some work (mostly on the exhaust side) balancing flow, bumping the compression ratio to 12 to 1, and .500 lift 300+ duration cam will get you an honest 240 horsepower - still on SUs. I personally think that $1,500 would be better spent on books and tuition for your college. But I like car stufffffff. Nooooooo mommyyyyy. We'll just have to wait for the dyno I guess. Quote Link to comment Share on other sites More sharing options...
X64v Posted February 27, 2009 Share Posted February 27, 2009 Some work (mostly on the exhaust side) balancing flow, bumping the compression ratio to 12 to 1, and .500 lift 300+ duration cam will get you an honest 240 horsepower - still on SUs. Is that rear wheel or flywheel? Just curious. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 27, 2009 Share Posted February 27, 2009 Current SAE on an engine dyno. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted February 28, 2009 Share Posted February 28, 2009 The stock ports on L6 heads (E88, N42, E31) head flow well enough to generate an honest 200 horsepower using the stock cam, pistons, and SUs. Some work (mostly on the exhaust side) balancing flow, bumping the compression ratio to 12 to 1, and .500 lift 300+ duration cam will get you an honest 240 horsepower - still on SUs. I personally think that $1,500 would be better spent on books and tuition for your college. Wisdom at it's best. Get your education then put a twin turbo LS7 in when you have the $$$$. In the meantime, you can port match the head and unshroud valves yourself. Next have a quality shop that knows how to work on an L series head do the rebuild and back-cut the valves. You'll still have a grand left over for school. Seems like a win/win to me. (Sorry Paul) Quote Link to comment Share on other sites More sharing options...
josh817 Posted February 28, 2009 Author Share Posted February 28, 2009 Wisdom at it's best. Get your education then put a twin turbo LS7 in when you have the $$$$. In the meantime, you can port match the head and unshroud valves yourself. Next have a quality shop that knows how to work on an L series head do the rebuild and back-cut the valves. You'll still have a grand left over for school. Seems like a win/win to me. (Sorry Paul) Well lets think like this... I COULD get a head ported and basically copy it on another head myself. Just a thought. I just really want as much power out of this motor as possible before the motor is a bit old and ready for a rebuild... Quote Link to comment Share on other sites More sharing options...
josh817 Posted February 28, 2009 Author Share Posted February 28, 2009 Wisdom at it's best. Get your education then put a twin turbo LS7 in when you have the $$$$. In the meantime, you can port match the head and unshroud valves yourself. Next have a quality shop that knows how to work on an L series head do the rebuild and back-cut the valves. You'll still have a grand left over for school. Seems like a win/win to me. (Sorry Paul) Well lets think like this... I COULD get a head ported and basically copy it on another head myself. Just a thought. I just really want as much power out of this motor as possible before the motor is a bit old and ready for a rebuild... Well... kind of dumb, pickup some junk cores and cross sectioning them would be much better. There are pictures of those floating around however you have to scale them properly. I tried to and based my work off of what I thought was safe. However... if I'm going to be putting lots of time into a head... make it something sweet like a KA frakenhead there are too many unknowns I would hate to mock-up something to run the cams and such because of all the forces, speed, and how important of a role they play... However... buying die grinder heads are cheap and I hear the electric ones are better than air powered ones so I wouldn't have to get a compressor. Men, this leads into the subject of "Its about time I start gathering up a tool collection." As much as I would hate to mention it, I think if my daddy ever passed away, his tools wouldn't be handed down. Step mom is a gold digger, she would probably sell them. If I want my own shop I guess it should start now. BUT if its a Datsun shop then I will stick with only metric! Haha I do love my metric sets. Quote Link to comment Share on other sites More sharing options...
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