240Z Turbo

Nice header you have built. I see you purchased a fancy 6-1 merge collector from someone as it enters the turbo flange. You can see the real short slip joints as the pipe slides into the other pipe. Here are some things I have learned and can share with you. Your design of placing many bends before the turbo is very good. This will help to absorb the thermal expansion of the header and prevent cracking. Here is the last thing I see you needing to do. The big killer with the heat and vibration is the header also supports the wieght of the turbo and wastegate. If you can somehow hang the turbo from above to support its weight you will take much of the stress off the header. You can use heim joints on either end of a rod, one at the turbo and one from a mounting point above the turbo. The advantage of a heim joint is will will allow movement about the joint. Here is a pic of the 321SS turbo header I have just built.

a good timing curve may retard 18deg total with 18psi of boost, but not usually in a linear fashion. For example, you may want to have retarded 2/3 to 3/4 of your total timing by 9psi and then taper off. So, if you started at 38deg by 9psi you would be at 26deg and then retard the remaining 6deg until you reach 18psi of boost. As far as AFR goes, 11.5:1 is good on pump gas and you can run as low as 12:1-12.2:1 on race gas. To answer your question, you can probably safely run 26-28deg at 18psi on 114oct race gas.

I am partially done fabricating my new intake. I used a 280zxt intake and cut the runners about 2" off the flange and then decked it on a mill. I milled the webbing between the runners down an additional .200" to allow for welding around each runner. I then traced the gasket onto the flange side and instead of hand porting I used a boring bar to remove as much material as possible. I bored it to 1.375" and the port is approximately 1.425". I will then weld my 1.625"(od) mandrel bent aluminum tubes to the decked flange. These tubes are about .100" larger ID than the gasket, but I have 2" to merge from the tube to the flange. Anyway, coming along as planned and will post pics some time soon.

309L is good for mild steel to stainless, but isn't the exhaust crap cast iron? If so, you need a nickel rod tig or stick. The O2 bung is not load sensitive so most anything will be fine. If is is mild steel(exhaust) to 304 then JohnC is correct and if it is 321 to mild steel then a 347 rod is preferred.

From my experience I think the problem may be this, in most cases a modified manifold will outflow the stock manifold. However, it may become too much as it is not balanced with the ability of the stock exhaust manifolds flow capabilities and the rpm limits of the motor. The cam may also play a roll in this phenomena(sp?). Also, because the L is not a high revver in most cases, the shorter runner cannot be utilized because of the rpm limits and thus the low end power is hindered. Only after I made a custom intake/exhaust and cam did my turbo motor pull strong up to 7200rpm and never peaked hp. Anyway, I think the best option for most is to cut off the backside of the plenum and port the runners where they meet the plenum and then slightly increase the plenum volume when putting it back together.

I seriously doubt the GTI-R manifold would have gained us any advantages for our goals. We have a total cost of about $175 in this manifold of which $100 was for the full radius velocity stacks. It is just a stock manifold cut/decked/welded and should flow like an SOB on the top-end. We care about ultimate power. I did get the Maxima Diesel manifold, but it came too close to the turbo's so Mike Gadwaw sent me a stock jobber which I will cut up and make my own. I should have something to post next week.

Well, it is $1100 worth of material, 321SS so it had better survive. Yes it will be supported from above.

HEHE!

Yes, the turbo's will be supported from above. The SS is 321 and is .065" wall thickness. The old setup made about 475@wheels with 16psi and 100shot of nitrous running 11.2@130. I hope with this setup and a different tranny the car will run about 137mph at 22psi and 100shot nitrous. I just finished cutting the other tubes and will have them welded later today.

NOT NGK, but NTK sensor and you just don't know where to look. HEHE!

Header will be done on Tuesday of next week.

No, not a machinist. I have had about 4.5 years of experience in a machine shop doing work on my research. I have learned to mig and tig. I can run the mill and lathe and have gained a lot of knowledge through tinkering and various school projects. I have just carried this knowledge/ability over and applied it to doing stuff for turbocharged applications. My passion is turbocharging and maybe oneday will start a high end shop. Not changing oil in a Honda!

This is the progress of our custom intake manifold. Stock runners have been chopped off and decked 34deg from flange surface. We have ordered 45mm full radius velocity stacks that will be welded to each runner. I have just machined the new fuel rail for the chevy style 950cc injectors. Only need to fab the brackets to secure the rail. I have also removed all the casting flash from each port. Will post more pics as we progress.

I welded the rest of the header myself today to get it 90% finished.

Well, this is the swap I am helping my buddy complete. Since I am waiting on the rest of my stainless for my manifold I am building this one for my buddies swap. It is 321SS and the turbo will sit front and center of the motor. It should be done next week. Click here for more pics!

Joel, I have a good center section from an 81 Maxima for cheap. It has the short 1-2 gears.

Just click here for a link to my site! They are the 1st 4 pics on the page.

Shane, this manifold will be available from SPD or you can purchase from my buddies shop for a reduced price. Within a few weeks it will be available.

I think if we take TimZ's setup he can expect to see 30RWHP difference. I hope that Joel will come down to Tallahassee to dyno his car to get a baseline before swapping to the new manifold.

Materials were about $1100, but that is 321SS. Do not be fooled by the seemingly simple design. Remember, the stock manifold has cylinder 1-4 entering the turbo area through a single 1.5" opening. Now you have cylinder 1-4 entering through two 1.75" openings. You have increased the flow area for cylinders 1-4 by 273%. Also, this is a tubular design so flow is optimized over the cast jobber. What does equal length by you in our street applications? Spoolup, but once you are going the difference between equal length and this style is not too much. Don't argue, these are not 1000hp car I am talking about, but our 400-550hp setups. Those fancy SS headers are nice, but unless you don't drive the car often or you have the turbo properly supported it will crack. I was forced to spend big bucks for fancy merge collectors and I had to place several bends before the turbo to absorb the great thermal expansion of SS. Also, I will have to support the turbo's from hangers off my intake manifold so it doesn't crack.

Well, these were sent to TimZ of what has been done thus far. This manifold is specific to a tangential split turbine housing, but you can see what you will be getting for about $850. Options of one for on-center, t4 or t3, external or internal wastegate. I still like my header better, but If I had a single turbo I would definitely get this one.