Midnitz

Nice packaging setup for your Turbo and IC. Have you ever thought of "standing the IC off" from the radiator? Such that the radiator also draws air in from a small cavity formed between the two? Have you looked into thermal coatings for the aluminum lines that route from the turbo to IC to intake? Thermal dispersant coating is applied on the exterior and helps dissipate thermal flux faster than aluminum can on its own.

I disagree somewhat with your assumption based on physics. First of all, the whale tail spoiler will have virtually 0 drag increase. ------------------------------------------------ The ENTIRE idea of creating a spoiler is to INDUCE DRAG to create downforce. any spoiler that does not induce drag is useless for downforce. This is the trade off.... This is due to it redirecting the air at the very back of the car upwards, and more effectively allowing the air going under the car to flow upwards and fill in the space behind the vehicle. ---------------------------------------------------- The spoiler induces drag by creating a high pressure surface at a chosen point on the vehicles' profile. BY inducing drag, we increase he profile of the low pressure albeit behind, below or above the car. That surface experiencing high pressure should be at the lower front of your car, and at a limited scope, to the rear of your rear wheels, just above the rear end. This reduces the separated turbulent region behind the vehicle and reduces overall drag. ---------------------------------------------------- You must be talking about the pressure differential between the air moving above versus the airstream below the car....The air above usually has more velocity (higher pressure) than the air below and as they converge at the rear of the car, (at leaston our old Zs) the air above pushes the air below approx 3-4 feet to the rear of the decklid....it then moves down towards the ground and moves towards the rear bumper and up again towards the decklid, creating an unstable rear end at high speeds...at 120+ MPH, this will create lift under the rear bumper and fuel tank as the pressure builds. This is why we must induce drag at this point....to "diffuse" this high pressure reversion that creeps up on our cars at 120+mph. The cost is an impact on the overall Drag Coefficient. Oh and as soon as a `spoiler' allows air flow between it and the car, as in that high/rear mounted 280ZXR, it becomes a wing. Wings work better higher as they receive cleaner air, and rearward because they place more force on the vehicle with a longer lever. --------------------------------------------------- Any surface on a vehicle that creates a pressure differential between its upper front and lower rear faces can be considered a "wing". While it is true that an elevated spoiler will receive a more laminar airflow, you will still have to fight the reversion I spoke about earlier. This is why Nascar vehicles use the integrated style spoilers, they are more efficient. Get a proper wing multi-element wing, as well as a smaller wing placed very close to the car down low which even MORE effectively pumps the air upwards and out from under it. Oh and while you're there, full venturi tunnels would be the go. I've just drawn up scale sketches for this on an S30, as well as designed radiator/intercooler/3 oil cooler placements and ducting. ------------------------------------------------ Actually, by manipulating the air under the car, you can make the deck lid spoiler more effective.... Fabbing "diffusers" for the creation of laminar air flow as it passes under the rear end is a great way to keep the air from moving too slow and creating low pressure under the fuel tank. The wheel wells are also a good candidate for air diffusers as they tend to develop high pressures. Probably make the car slower.. hehe. Dave I like your enthusiam!

here is a small pic of my progress....I will attach better pics in the future...as time is short...

re: Sure the setup is not ideal, and I am not all together convienced you can make much improvement, but it is the most efficient use of the header. Going custom is cool, but in this case not necessary. I am running a log style header from South Flordia Performance and what a nightmare that has turned out to be. I had to rework the part three times to get it to work. ------------------------------------- JeffP, You are right, nissans L28T manifold is far from optimal, it is very inefficient....exhaust pulses being shot into the primaries of other exhaust ports...Using only the ambient pressurization of the manifold to engage the turbine.... The turbo flange position WRT exh primaries needs to encourage directional orientation of exh pulses, this prevents exh pulse reversion (that is present in the stock manifold), this will make the turbo we choose more sensitive to exhaust pulses, not just ambient manifold pressurization....by implimenting this, we can help mitigate turbo lag and the over saturation of thermal flux. The only problem I see here is we will have to use thermal barrier coatings further down the exhaust pipes... What I intend to do: 1. work with the packaging clearances Nissan has given us.... 2. Reroute the PCV from the valve cover to TB hose....to valve cover to air cleaner tube bung (prior to the turbo) 3. Design and make the header as directional as possible 4. Tap the wastegate into the collector as closely to a Y pipe config as possible on both sides. With multiple iterations of CFD studies, I am CONFIDENT I can improve upon what is out there. The difference is I am in it for the enthusiasm....not to make a buck...so time is not an issue for me. One more thing, I will not be running stock boost pressure. I plan on running 16 psi, perhaps 18. My target is 400bhp and 325-350 lb ft of torque.

Hughdogz, What you stated indeed makes sense.....I made the changes to the reference geometry plane.... I probably will not center the flange on runner #5, it will probably center on in between 4 and 5 to even the length of the primary tubes....and tilt the flange another 5-10 degrees. I will be building this using tig-welded stainless tube I'll keep you guys filled in.... I will perform a mockup using the T3/T4 to help guide me with constraints. I'll provide pics of this process as well. Thus far, the rotating assy has received lightening treatment and knife-edging as well as the cryo treatment. -Planned are Pauter "polished" ultra-lightweight billet rods. http://www.pauter.com -Slightly Dished CP Forged aluminum alloy pistons with dry-film coated skirts. -Ferrea under-cut stainless valves with dry film lube coated valve stems. -CNC machined bulkheads on engine block to remove stress risers. -Main Cap stud girdle -lightweight billet flywheel -BW T5 trans -Upgrade to R200 LSD What do you folks think of Haltech ECUs? I want a coil pack per cyl setup. Thanks!

Cmon guys.... Thus far, I have the exhaust flange and the rectangular to to round primary tubes modeled in 3D.... Today, I started to model the front most primary exh tube, I can get a bend radius as tight as 1.625 (centerline to bend pivot), I also incorporated the 45 degree transition for that tube to make it horizontal and start its run towards the rear. My goal is to combine the 6 tubes into 4 inlets that run straight into the turbo flange spacer. So....the last piece of info I need is the turbo flange to cylinder head dimension.... If you guys helped, I wouldn't rule out sharing info, heck I may just build a few extras and ask for the cost of material. Anyone? Next post will have Jpeg of the solidmodel. I will also post CFD results to show how this baby flows.

If you will use thermal dispersant, coat the exterior of the intake manifold. The black coating has a high emissivity in the infra red range. Coating the exterior of your exhaust manifold/headers, turbo exhaust housing and downpipe will prolong the life of the thermal barrier coating as you will experience a thermal gradient in the coated substrate that will take some of the direct heat from the exhaust. Exposing the barrier coating by coating the interior shortens its life. CermaKrome is the more cosmetically apealing coating....there are others that stand up to higher temps, but don't look as good.

The coatings are more of a build sequence issue....if you have it apart, it requires small semi-tedious tasks to get the coatings applied. The benefits will far outweigh the costs. If the motor is built, stick to coating things like the intercooler, the intake, oil cooler, exh. manifold or header, turbo housing etc.... The flow #s Tony is talking about are a good approximation... you can squeeze more flow out of the ports but it requires more than a bit of carbide and sanding roll/flap wheel work. Getting a dummy head and optimizing the intake and exhaust ports for the best flow is usually the way to go. This is where the inner bore diameter measuring tool works great to approximate dimensions at given incriments. Casting a die of the ported cavity and cutting in half for fit checking of any subsequent ports is also a good thing if you want to balance the ports....flow benching to verify a correlation is a must.

Calgary, It makes sense to coat both the exhaust manifold/header, turbo exhaust housing and downpipe with the cermakrome coating. The biggest caveat is the prep work before the coating, make sure the aluminum oxide is new and uncontaminated. Make sure any and all portwork take place before the coatings. The intake, after portwork, should get coated with thermal dispersant coating to just the exterior and because these are "Dry" intakes, have the people doing the portwork perform normal bead blasting on the interior of the intake prior to re-welding. If you can do the coatings yourself, make sure you spray the thermal dispersant on lightly, not too wet. Other items that can and should be considered for thermal dispersant; Oil pan, oil coolers, intercoolers, routing tubes, impeller housing. Other coatings to consider, Dry film lube coating the piston skirts, valve stems. Oil Shedding coat the wrist pin side of pistons, the top surface of the cyl head, interior surface of the valve cover.

Monzter, excellent picture of the cut intake...this is by far the best way to massage your intake runners. The main mistake people make is they enlarge the runners too much.... enlarge them the most as they leave the plenum and the volume should reduce as you approach the cyl head interface....this drop in volume will maintain air intake velocity and help throttle response. I would gasket match, the velocity of the taper on the intake runners would help mitigate reversion due to cam timing overlap. re:techline coatings I swear by the coatings and use them on all my engine builds....infra red prometer and thermocouple tested, the coatings work well and will improve your engine's efficiency. I reckon it will improve turbo lag due to retention of heat in the exhaust manifold or header and turbine housing. (I see a pre and post coating dyno study in the making here) KTM: I disagree....the thermal dispersant coating on the exterior of the intake should be considered, since it will improve the intakes' ability to dissapate any heat faster than if left uncoated. I believe techline calls it the TLTD coating The con: they only sell the good coatings to businesses....so I have to order from work.

Now get the intercooler and spray on some thermal dispersant coating to optimize efficiency.

the modifications totally make sense, I don't understand why Spearco wouldn't perform their own CFD analysis. The first velocity analysis cross section is right on.....the consistent size as you progress away from the inlet creates a pressure drop....thus a drop in velocity....by adding your radiused end, you have diminished volume enough to stabilize velocity across the whole intercooler. The plenum divider also killed any low pressure spots by splitting the volume into two....and making the forced airflow more directional, this also mitigates the possibility of unwanted turbulence. Excellent work! Now if every supplier could excersize this level of dilligence!!!

Calgary280zt, The numbers for airflow are decent, but what are the valve lift vs airflow at .100 inch incriments? 0.050 incriments? By knowing the dynamic flow characteristics of a cylinder head, the camshaft designer/grinder can zero in on the cam duration/lift profiles and LSA design. In most cases, a typical Turbo cam profile emphasizes the exhaust side duration and lift to help mitigate turbo lag while LSA usually won't dip under 112. In most cases a thorough flowbench analysis can yield you lots of good info to help you design the supporting components. Insufficient good data can leave you building a "detuned", powerplant.

Gentlemen, I have some questions.....most relate to dimensioning and clearances. 1. I am looking for the dimension of the two constraining vertical planes.... the flange (cylinder head mating surface side) to the Turbo flange (Turbo mating surface side). I know that the larger the turbo, the smaller this dimension will be due to engine bay and steering assembly constraints. Let's assume I will use a hybrid T3/T4 turbocharger, 2. Will this further constrain the space I have to work with? 3. Does anyone have drawings for a T3 or T4 turbo? 4. Does anyone have drawings for the exhaust flange for an N42 head? Once done, I will share pics of the design and look for some feedback. For those who don't know me, my name is Rob, I live in the SF Bay Area, drive a family owned since new 76 Z, and am looking to add a turbo to a custom built rotating assembly to my N42 block and head. I am a Mechanical Engineer and have some experience on automotive engine building, cylinder head port and flowbench work. I can also perform some cfd work, Solidworks, ProE, COSMOS FEA. I love to fabricate, machining and welding parts and just tweak things until they are optimized. I look forward to sharing info and having fun with my engine build

If we were tuning our intake tract for the second, third, fourth or even the fifth wave, then it would be at the point where either of these waves is just approaching peak pressure that we would want the intake valve to open, therefore allowing this column of air and its kinetic energy to “shove†even more into the cylinder than the piston could “suck†in on its own, ie. Greater then 100% Volumetric Efficiency, or VE for short ------------------------------------ Hence why cylinder head design, intake design/tuning and camshaft profile are important..... More modern engines have variable valve timing as well as variable intake tuning...to help widen the Band of peak VE%. Good post Paul.

Its funny you say that the N42 offers the larger overall power potential... I found I even had to weld some of the exhaust ports a bit to improve port matching to the header flange. Now if I can only find a place to port my intake.... L28 N42 head and intake

I think that removing the liners is generally a bad idea....most of the work needed on these heads is at the valve bowl and the valve guide, unshrouding the valve is also a must with the newer heads as the valves are larger. Flowbench work is also a must as balanced flow is important. In some cases, I have welded the N42 exhaust ports because of the cast core shift is so bad and the ports are too large for practical header flange interfacing....Effectively raising the exhaust port floor up by up to 2 mm in some cases and adding up to 2mm to the sidewalls to make up for shifts in the cast cores.... Also I have discovered that leading up to the valve guide on the intake side, there should be a splitter that progreesively tapers air around the guide such that the guide itself doesn't produce unwanted turbulence and cause the air to tumble..... This is why being able to weld aluminum and perform clay work along with a flow bench is so necessary. To find out what works at given valve lifts.

WingZR0 Your Z exhibits the makings of a compromised cylinder head....the milky oil or coolant clearly tells you of your problem..... the white plumes of Vapor exiting your tailpipe confirm it. In the ther gentleman's case, it sounds like he may have the infamous blueish smoke that is a tell-tale sign of bad valve seals, these are located just under the camshaft area....right in the line of fire of the oil spouts in the cams itself or the external rail.... Also be sure to check the TPS for proper voltage, if it is out of range, adjust it....if still out of range, clean the electrical contacts....a wet boot receptacle will short the signal out and keep your rpms below 2500rpms.

You are indeed a lucky man...Those Boss302s weren't meant to be ground-pounding straightliners like the 427s, 428s and 429s of that day....these cars were designed for the trans am circuit....where the large-port head 302 can do its thing at or above 4500rpms. They handle quite well and are worth big bucks now....$65+ K for a #2 car.