David K Posted June 30, 2003 Share Posted June 30, 2003 I found this on an Australian z club website. More info would be nice, if anybody knows anything. I dont get what benefit a cross flow head would have. The air is let in the chamber, the valve closes, the air is squished, it is ignited, the valve opens, the air is pushed out, and it happens all over again. Now since the air flow does not maintain a straight air path due to the air being, lets say....'temporarily stopped', then what benefit would a cross flow head have over an L series head? I dont see how it could be any better, since the air flow still follows the same path once the compression stroke occurs, and what direction the intake flow comes from really doesnt matter as long as it gets in the cylinder smoothly, and the valve closes. Now i understand about the intake manifold temperature issue, but if you are able to solve that, how can a cross flow head possibly have a performance benefit? Ive come to the conclusion the cross flow head is a waste of time and money, IMHO. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 30, 2003 Share Posted June 30, 2003 There are 2 things cross-flow heads are better at than non-crossflow. One is intake/exhaust port size - with 6 inlets and 6 outlets on one side, you can see they could be bigger if the intakes were moved to the other side. The other is the proximity of the exhaust port to the intake port, and larger ports are worse, as there is less metal in between - you will get a cooler charge into the engine. Quote Link to comment Share on other sites More sharing options...
David K Posted June 30, 2003 Author Share Posted June 30, 2003 If people, some here on the website, are going to spend time and money on fabricating new heads, then why dont they do something like make our existing head taller? Bigger ports could be had due to more room, and the stock manifolds and equipment could still be used. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 1, 2003 Share Posted July 1, 2003 With LY28, you have to alter the motor mount agnle and transmission bell housing to fit it under the hood. Quote Link to comment Share on other sites More sharing options...
turbobluestreak Posted July 1, 2003 Share Posted July 1, 2003 David K I'm swaping an RB20 head to the F54 block that means that we can use JDM parts and save a lot in fabercating of cams, manifolds, and a lot more parts. As of now I'm trying to get an VG30 oil pump to mount on to our blocks then convert to timing belt and swap on an RB head, for extra power. tbs Quote Link to comment Share on other sites More sharing options...
DAW Posted July 1, 2003 Share Posted July 1, 2003 I'm tellin' you tbs, the head water jackets are too close to the bore! DAW Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted July 1, 2003 Share Posted July 1, 2003 I was thinking the exact same thing David, the flow is interupted by compression and combustion...the only time flow might benefit is during valve overlap. I just think you need some good insulation between the intake and exhaust manifolds (not just the thin factory heat shield), maybe run the motor a little cooler, and it'll be good enough for me. Once port velocity increases, I don't think the intake charge will have time to significantly heat up (unless the fast moving air carries more heat away from the head...not sure). These heads perform pretty well anyways, with peak power at 5500-6000 RPM on stock L6 motors. Go to Zhome.com and look up Electromotive's NA 280ZX...over 300 HP out of a 2.8 liter (over 100 HP/liter), just as much as most high performance crossflow DOHC heads. Its not a perfect head design, I do realize that...but it has enough potential that I think most people don't need to worry about the fact that it is non-crossflow. Unless you are trying to break records... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 2, 2003 Share Posted July 2, 2003 Didn't the Electromotice Z put out around 600 HP? Maybe I'm thinking about the wrong car. But this guy built his own custom fuel injection system, had massive heat shielding on, nice turbo, I/C etc. Theres a few pic in that "how to modify your datsun SOHC engine" book. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 2, 2003 Share Posted July 2, 2003 I added alumium covered high silica blanket under my factory heatshield and I can now touch the intake. Quote Link to comment Share on other sites More sharing options...
Mudge Posted July 3, 2003 Share Posted July 3, 2003 Also, you can move the exaust to the other side avoiding heat soak on the intake side of things. Quote Link to comment Share on other sites More sharing options...
Guest z1 performance Posted July 5, 2003 Share Posted July 5, 2003 Mudge has the main benefit right there...the ability to get the intake and exhaust sides seperated. I considered going to the cross flow head whe building my motor, but it turned out to be far less expensive to go with the built head I ended up with, and performance would not have varied much from the OS Giken setup (the one I had considered) Quote Link to comment Share on other sites More sharing options...
David K Posted July 5, 2003 Author Share Posted July 5, 2003 The fact is that the crossflow head is near impossible to find, so whoever wants to use one, has to either fabricate it, or spend lots of $ to modify an existing head to work...and we are talking about thousands. Then you get to the performance gain you get with a crossflow head over the nissan L head. Its tom foolery to even start fishing those waters, IMO. For at least 5% the $ you spend completing a crossflow prototype, you could completely solve the cooling issues with the manifolds being so close together on the L head. For those who stand by the crossflow head, show me some #'s to prove that its worth all the time, money, and effort to re-invent the wheel. There was a reason for discontinuation, and still is a reason for non production of a cross flow head for the L series engine. Its plain as day that its basically not even worth it. I hope this post doesnt steer anybody away from following their dreams of producing a crossflow head. Quote Link to comment Share on other sites More sharing options...
Guest zline Posted July 6, 2003 Share Posted July 6, 2003 A big reason that it was disqualified was the fact that it was so expensive and the factory works cars could use it because they had huge budgets, stay inside the same race class but put down 10-12% more hp than the smaller race teams. The head was outlawed because the smaller "sunday club" racer didnt have or didnt want to spend the resources on the crossflow head, not because it wasnt a great thing - in a matter of fact it was, but for our performance levels you're right - spending obscene amounts of money for one more cam and cooler manifolds doesnt make any sense, build a high comp 3.1L with 3 50mm webers jet em right and put a good cam in it and you'll be smiling just as much - and have a big wad of cash left in your pocket compared to if you wanted a crossflow head. sorry for being long winded. Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted July 7, 2003 Share Posted July 7, 2003 What about using ceramic coatings on both the intake and exhaust manifolds to reduce heat...and on the insides of the ports? How about using a completely separate cooling system for the intake manifold...have its own small radiator and pump. It could run at a lower temp than the rest of the motor. And of course, decent insulation between the intake and exhaust. As far as Electromotive goes, they had both an NA and a turbo car. The NA car made about 300 HP, and the turbo car made about 600 HP. Quote Link to comment Share on other sites More sharing options...
Guest zline Posted July 7, 2003 Share Posted July 7, 2003 you dont need all that stuff, an intake manifold radiator? ive never even heard of that!! just get proper heat shielding if anything jet hot coating and you're good. Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted July 8, 2003 Share Posted July 8, 2003 Who cares if you've never heard of it...its just an idea. The idea is just that the manifold runs at the about same temp as the engine since they share the same coolant. If they each use a separate cooling system, the manifold could run at a cooler temp so the air passing through it wouldn't absorb as much heat. And yes, proper heat shielding and jet hot coating is without a doubt the way to go, the cooling system thing was just another idea. Quote Link to comment Share on other sites More sharing options...
Guest zline Posted July 8, 2003 Share Posted July 8, 2003 chill out man. talk about jumping down a guys throat hell. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.