Xnke Posted June 10, 2015 Share Posted June 10, 2015 Peak torque won't be inside the L28's revs-per-dollar, I'm afraid. Studying K20A engines, they peak at 8000+ RPM, pretty much regardless of displacement, headers, cams, induction...they just want to rev. On the other hand....that should point to an engine that just needs to be spun harder if you want more power... Quote Link to comment Share on other sites More sharing options...
1vicissitude Posted June 12, 2015 Share Posted June 12, 2015 After spending 10k on this head (assuming that's the final cost), what's another 3k for a fully counterbalanced crank? It can built to Rev to whatever in this price bracket. Quote Link to comment Share on other sites More sharing options...
bradyzq Posted June 12, 2015 Share Posted June 12, 2015 Remember that the K20A2 is an iVTEC motor. Unless you go all out and make your new 6 cylinder K-series head iVTEC, you won't have the wonderful wide torque band they have. They only look peaky because the torque just doesn't fall off, seemingly ever. Check out this dyno graph of that motor with boltons and a tune. 90% or greater of max torque between 4500 and 8000RPM. 80% or more for the whole dyno pull. Heck, the torque PEAK is 1000RPM wide!! With conventionally timed cams, I would guess you can still get a nice torquey motor, but it won't be as flat a curve. http://www.av-engineered.com/site/news/224whp160tq-stock-k20a2-dyno-tuned Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted June 12, 2015 Share Posted June 12, 2015 Lol 150 ft-lbs across the board. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 12, 2015 Share Posted June 12, 2015 Lol 150 ft-lbs across the board. Yeah, that's begging for boost. Quote Link to comment Share on other sites More sharing options...
Derek Posted June 13, 2015 Author Share Posted June 13, 2015 (edited) Here is a link (I may have posted it before) about putting stock A2 cams in an A3 head and using the exhaust rockers on the intake. He killed the iVtec rockers but kept the variable cam timing. http://www.k20a.org/forum/showthread.php?t=66643 It's a pretty good thread with dyno results posted. Based on everything I calculated, my head in it's stock form will flow more along the lines of a ported A2. That remains to be seen obviously. I'm revisiting iVtec because I've had a few inquiries about it in PMs. But I'm only revisiting it to the point of making sure there is cast aluminum everywhere it needs to be in order for SOMEONE ELSE to implement. There is a whole ton of things that have to happen for iVtec to work. Cams and custom timing chain hub come to mind as well as a ton of extra machine work. Possibly custom cam towers or at the very least highly modified towers. Hopefully someone with really deep pockets will make this happen. If I had to guess I could easily see another $4000.00 or more for taking it to that level. But if someone was thinking about plunking down 40 grand for an OSG head, 15 or 20 grand for a 6 cylinder full iVtec head looks pretty appealing. Edited June 13, 2015 by Derek Quote Link to comment Share on other sites More sharing options...
280zex Posted June 14, 2015 Share Posted June 14, 2015 I know you have heard this already, but thanks for all the information you have posted in this topic. I obviously would like to have one of your heads, but I just don't have the $$$. Maybe if I decide to sell a testicle or something........... Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 15, 2015 Share Posted June 15, 2015 Brady is noticing the things I did... Yeah they peak "high" when set up that way...but it's all in cams. A stock Datsun Crank is well within its capability at 8,500 rpms easily...if you set it up that way. You can rev the hell out of it and make interesting power. Or, you can put a mild boost to it with the flow it produces and have an engine that has stump pulling torque at 2,500, which pulls to a massive horsepower peak using less than 12psi at 8,500.... Acts for all intents and purposes just like a very large N/A that revs to 8,500... A head flowing 220CFM on the inlet with a cam that maximizes that flow for turbo applications will come on at 3,500 just like the stocker N/A, yet pull like a freight train past 8,000 at 12-15 psi and make well over 600HP This head will flow more than that... Quote Link to comment Share on other sites More sharing options...
seattlejester Posted June 15, 2015 Share Posted June 15, 2015 Ah, the v-tec killer arrangement. One of the few users who did implement that for the A3 setup added boost and then went back to the traditional i-vtec setup with boost due to a lack of torque until you got into boost/higher rpm's. He found drivability off the line at regular speeds was startlingly poor without the variable cam for the A3 motor. The gains when you romp on the throttle are great, but given the K20's poor torque the sudden loss of low end torque can make regular driving quite difficult. For an L28 though which seems to naturally have more torque I'm not sure if that would be an issue. Quote Link to comment Share on other sites More sharing options...
Derek Posted June 15, 2015 Author Share Posted June 15, 2015 Ah, the v-tec killer arrangement. One of the few users who did implement that for the A3 setup added boost and then went back to the traditional i-vtec setup with boost due to a lack of torque until you got into boost/higher rpm's. He found drivability off the line at regular speeds was startlingly poor without the variable cam for the A3 motor. The gains when you romp on the throttle are great, but given the K20's poor torque the sudden loss of low end torque can make regular driving quite difficult. For an L28 though which seems to naturally have more torque I'm not sure if that would be an issue. There is like 40 pages of people who have made the mod on that link I posted. There are videos and dyno reports so it's more than a "few" users. Now if you meant to say "one of the few users that added boost" then that's a different animal. The overall feel I got from the thread was that most were happy with the mod. Not looking to pick a fight just looking to create a balanced picture. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted June 15, 2015 Share Posted June 15, 2015 No worries, I mean it has been many years since I was up to date on the rsx forums, it could very well be a more wide spread mod by now. I felt the a2 cam/exhaust rocker on intake swap didn't come into play as I was finding interest elsewhere. I just remember the example because it was so startling given the praise the mod was seeing and the gains, that one of the early adopters decided to swap back. It could have just been the addition of boost made the desire for more power top end moot, but alas, I still remember it. For the k20 in the rsx any mod that drops the torque makes a real difference in which gear you can be in on hills and such. Given that a 240z weighs 800lbs less, has two more cylinders, and 0.8Liters more displacement, I doubt it will be as big a factor. Brian Crower has had Vtec killer cams for a while, so I'm sure it works. Maybe a blip on the radar and anecdotal at best, but one person did go back.,On a different motor on a different car with different mods in retrospect probably not even worth mentioning, lol. Carry on sir, carry on. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 16, 2015 Share Posted June 16, 2015 Most of those are terribly mismatched turbo setups as well. Many here aren't making boost on their L-Series until 4,000, 4,500 under some misconception that smaller hot side A/R's will "restrict the top end" when in fact they give you boost sooner, FAR more power "under the curve", and greater drivability. What is really needed is an understanding that conventional boost control schemes are 50's technology, 60's at best. In the 80's there was a device called "the turbo group fueler" which utilized the smaller A/R to run double boost at lower rpms, and taper it back as rpms rose. This was on the premise that sufficient fueling existed for maximum horsepower in the stock setup for top RPM use...but because no flow was generated down low, that excess fueling capability was wasted. The device utilized it. Using a suitably sized A/R and staged wastegate a control scheme whereby 17psi runs at 1,700 rpms...and tapers or maintains to redline. You can do it in an L-Series...you can do it on this. It would be such a waste to see strictly conventional "stuck in the box thinking" limit the power curve on the motor. Power comes from flow, and this head has it. Pump it up and watch the torque bump up from 1,700/2,000 to where the dual valves start shining in a N/A revving application. Then again, running 4.44 or 4.62 gears isn't going to kill anything. The little A12's ran 4,000-4,400 rpms at freeway speeds and lasted forever as well. High Nickel Blocks were used for a reason! Quote Link to comment Share on other sites More sharing options...
Mack Posted June 16, 2015 Share Posted June 16, 2015 HE351VE turbo. 'nuff said. Quote Link to comment Share on other sites More sharing options...
rooger82 Posted June 25, 2015 Share Posted June 25, 2015 Over a week with no updates, Who else here checks this thread for updates as soon as they get on HybridZ, I know I am not the only one. It starts off my work day. Quote Link to comment Share on other sites More sharing options...
Derek Posted June 25, 2015 Author Share Posted June 25, 2015 (edited) This will have to hold you for a bit:) Final design on the valve cover. I rendered it a gunmetal grey which is the color I'm going to get it powder coated. Here it is on the head. This is a rendering from the casting so there is a ton of machine allowance on the outside rim where it meets the head. It will be a better fit after machining. Camshaft castings are on the way to me and I should have them on Tuesday. Waiting on the foundry to pour the first manifold. Other than that things are in a bit of a holding pattern. Derek Edited July 7, 2017 by Derek Quote Link to comment Share on other sites More sharing options...
88dangerdan Posted June 25, 2015 Share Posted June 25, 2015 That sure is Purdy Quote Link to comment Share on other sites More sharing options...
LanceVance Posted June 25, 2015 Share Posted June 25, 2015 As a graphic designer, photographer and a Z enthusiast I'm sure you can do better than plain text for a logo! Shoot me a PM if you're interested in making something a little more flashy before you do the final machining. Quote Link to comment Share on other sites More sharing options...
Derek Posted June 25, 2015 Author Share Posted June 25, 2015 That sure is Purdy Thanks! As a graphic designer, photographer and a Z enthusiast I'm sure you can do better than plain text for a logo! Shoot me a PM if you're interested in making something a little more flashy before you do the final machining. As a pattern maker I LOVE plain text Thanks for the offer but I'm trying to emulate the Nissan text from that era. And that was quite plain and blocky. I'm open to improvements on plain and blocky but it's going to be plain and blocky no matter what:) Derek Quote Link to comment Share on other sites More sharing options...
rooger82 Posted June 25, 2015 Share Posted June 25, 2015 Looks like its Lego brick inspired. Quote Link to comment Share on other sites More sharing options...
Derek Posted June 25, 2015 Author Share Posted June 25, 2015 (edited) You mean like this lego brick:) Edited July 7, 2017 by Derek Quote Link to comment Share on other sites More sharing options...
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