thehelix112

A cowl `induction' bonnet is called that because air flows IN to the engine bay via it. This occurs because the cowl entrace is right at the high static pressure zone created by the windscreen. A cowl induction bonnet will do exactly nothing to benefit engine bay temperatures. You want vents that are placed at the point on the bonnet where the airflow is fastest (lowest static pressure). I imagine this is potentially just rearwards of where the bulge starts. Dave

I wouldn't be surprised if the superchargers they are talking about are Toyota 1GGZE SC14 superchargers. I ran one on my L28 a while back with a Holley draw through. Waste of time and money for a measly 5psi rubbish IMHO, but would be different. Dave

10psi = (14.7+10)/14.7 = 1.68 Pressure Ratio. 1 pressure ratio is atmosphere. Dave

I really wanted to tell you what you want to know, but I suck at typing. Dave

Jon, Very good point, which I had forgotten. I'm sure there is a trade off somewhere along the line. You might also be able to delay the spill around the sides of the car (C-pilar) towards the point of separation and reenergise the flow that way? Dave

Hmmm.. Are you unconcerned that the alcohol mixture could potentially be sprayed everywhere by the BOV? I'm sure you can set it up with the AEM so it shouldn't, but its physically possible? Aside from that it looks damn nice. Lemme know if you need moral support during the first drive. Dave

Yes it is dependent on speed. The faster the speed, the more energy the air has, as the more willing it is to remain attached longer in the face of an unfavourable pressure gradient. The whale tail is interesting in that it gather's air from the sides of the car and redirects them onto the spoilers. Something else for me to think about. Dave

From what I have read (limited) I would guess the following: 1. Vortex generators should be placed just before (I think?) the point of flow separation down the hatch, so it would be good to test that with some tape and wool before you decide where to put them. 2. Vorticies produce LOW pressure on the surfaces they interact with due to the increased speed of the air travelling about the vortex core. (Longer helical path as opposed to straight line, in the same time). You don't want low pressure on the top of the spoiler obviously. 3. The vortex generator should stick up JUST past the boundary layer, which I have heard people say is only around 2-3cm, so made sure they're not too big. Though new BMWs and the like look to be more like 4-5cm, so who knows? 4. I'm with Jon veritech, the louvers you drew would not do much I think. 5. All this leads to is, vorticies are great where you want low pressure and/or delayed flow separation for drag reduction. At a guess I wouldn't think they'd interact well with any topside spoiler/wing. Dave

I would hazard a guess that if you want people to start believing what you say, it would help if you provided something akin to an explanation? ``I'm an engineer, I can tell by looking'' doesn't hold much weight with me sorry. Doesn't necessarily have to be in a wind-tunnel. A few coast-down tests with(out) the wing would soon tell if it had any effect on drag. As for downforce, there are a few ways to approximate it without a tunnel, suspension compression, video footage, etc. Aftermarket parts are designed only for looks? Really? I'd never've guessed. We agree on something at least.

Have any form of analysis to back up that oh-so-certain comment? If not, I suggest you leave the option open. You may well be right, but you may well be wrong. Everything I have read in a couple of aero books always says `it depends ENTIRELY on the specific vehicle'. FWIW, the simple nascar spoilers are shown to reduce both drag and lift, and these cars have nasty ugly square fuel cells at the rear (about as far from underbody devices as you can get). Refer to McBeath `Competition Car Aerodynamics' or the appropriate Aerobytes article (from RaceCar Engineering). Dave

First of all, the whale tail spoiler will have virtually 0 drag increase. 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. This reduces the separated turbulent region behind the vehicle and reduces overall drag. Refer to McBeath and or Katz and or any Nascar for further evidence of this. If it were me, I'd be making a simple alu sheet angled spoiler for its tunabiliy. Easier to find the appropriate front/rear balance by extending the spoiler and or making it steeper. 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. 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. Probably make the car slower.. hehe. Dave

My steering wheel is on the wrong side, and the car is currently more than 6000km away from me. :S Dave

Thats a Ford Falcon XR6T 4.0L straight six engine built my nizpro. http://www.nizpro.com.au and you can download the movie. Over 1000 (australian) hp IIRC. The XR6 Turbo comes factory with a GT35R-based turbocharger. Would be fun if the car didn't weigh 1700kg. Dave

Wow. Dave

AdrianZ, Did you read my post? Please don't forget these are DynoDynamics (Australian) dynos. According to Drax they read atleast 17% under DynoJets. Go look at the video of the 852awkw, then do the maths. 852 * 0.7457 (to hp) * 1.17 (to dynojet) = 1336hp. Did I mention they then rebuilt it for more boost (no wastegates) and more revs (13000rpm). Surely you can't do that for under 50K? Dave

Things to check: 1. The diaphram actuator isn't leaking. Connect a hose and blow into it. 2. The wastegate flap isn't stuck shut. Manually try and move the actuator rod and flap to make sure its not jammed. 3. All boost lines to and from the manual boost controller and diaphram. Good luck, Dave

NP. Dave

Check that there is a Garret tag attached to the CHRA. Get P/N, ring Garrett and ask what it is. Dave

That is the design of a front diffuser yes. I have finished reading Katz's book and think I've got a much better grasp on them now. Also after poking around Mullannes corner today, it seems that it doesn't matter so much where the air after the end of the front diffuser goes, aslong as it is out of the car and it is free to get there easily. In this case what you are trying to achieve is a front wing. The upsweeping underside coupled with a little high pressure on top, voila. I have just traced the 240z chassis schematics from the brakes & chassis forum from my laptop screen onto paper so I will have a sketch over the next little while and see what I can come up with. Will post results if anyone is interested. Oh, seeing as I plan on using the 280YZ, if anyone who has the kit could give me some measurements (any really) that'd be awesome. Dave

Nice post Tim! The incorrectness of such web calculators had occurred to me but I hadn't spent any time thinking about why. My neurons thank you. Dave

My fav is the 852awkw run. Please note, that is all wheel kilowatts. Convert that to hp, then convert it to the equivalent dynojet hp (+17%) and you have over 1300awhp from 2.7L. Then they rebuilt it to rev higher and run more boost. Insanity. Dave

DCZ, Spot on. A larger A/R housing (in a given family, ie T3 or T4) will mean more flow potential, but also more lag. Note when I say lag I mean lag, not boost threshold which (if you are driving hard) only really matters once. The rule of thumb is 1lb/min is good for around 10hp. So I would be looking at maps that are good for atleast 30lb/min, more like 35 to give you room to play if you so choose. Largest, smoothest flowing dumppipe you can get is always going to be a good thing. Dave

T4 compressors aren't (to the best of my knowledge) named in stages. Thats the turbine wheels. T4 compressors are broken into two categories B and E, and all listed here: http://www.turbofast.com.au/flowmaps.html Are you getting confused with the `trim' series? TO4E series are named in trim numbers, with a 57 trim being quite common. The way you have written it sounds like the turbine trim. T3/T4 hybrids I believe were originally developed for tight-ass people who didn't want to have to go external wastegate, but wanted more compressor flow. Indeed most T3 housings are internally gated (with some exceptions, the GT35XXR series for example), so you shouldn't need a new manifold/ext gate. Tell us correctly and precisely what you are talking about and we'll go from there. IMHO 0.63 T3 turbine housing is overly small, but probably still enough to meet your 300 (fw/rw?) hp requirements. Dave

John, Thanks mate. Much obliged. Dave

China-spec is always a worry. Don't forget Cunningham rods. They have an excellent reputation from what I can gather. Dave