260DET

Routine check showed that the four M8 brace bolts to the firewall had loosened up quite a bit after some track work, obviously there is body movement between there and the area forward of the firewall. I just hope that tightening them does not result in another handling change.

It would not want to bolt to the car, movement on the gearbox mount would wreck it.

Softened the front ARB up a bit, not a lot, and the understeer is gone. In fact it's a bit oversteery now so some of the ARB change will be reversed. It certainly happens that once the body is stiffened up small suspension changes can make a big difference.

Of course but most people start off that way and then look for more and more speed, it's natural. Too much air flowing through the front will, from what I can see of your car, end up going under the car lifting it as well as slowing it down. There was pic around here years ago of someone racing on one of your great speedways who had closed off a lot of the grille opening, apparently it hauled big time and sounded like max fun.

Does look good and the splitter should be functional. But for race track high speeds there is way too much front air intake area which will result in lots of drag and slow you down. And we don't want that do we.

The Z's front ARB has rubber bushed links, it would be quite easy to adjust their resilience either by slackening the retaining nuts or replacing the bushes. The sort of thing that can be done at the track too, good idea.

Tremec 5 speed is good, unless you really need a six speed which is relatively heavy and clunky. As has already been said, to fit a gearbox which does not bolt up requires either modifying the bell housing or using an adapter plate. That's it.

Going through the log book reminded me that the car has a history of sensitivity to low speed bump adjustment at the front and understeer. Easy place to start. Front track is at the max already John but I like the idea of trying changes that will potentially benefit the car overall. My first thought was tyres RZ but they were OK a couple of weeks ago so trying reversible suspension changes first seems to make sense here, rather than get a new set of tyres just yet.

That makes sense, thanks.

On the 280ZX which used to handle great but now on the same cold semi slicks has lost nearly all grip on turn in after fitting a triangular brace from strut top to strut top and back to the reinforced center of the horizontal firewall seam. The difference, with nothing else changed, is spectacular. It was a circuit track test day for the auto so we were concentrating on other things but it was like driving on ice at the front, with cold tyres anyway. Everything is adjustable on this Z, including rebound and low and high speed bump. Any suggestions where I should start?

Let's clarify the terminology here which I understand is universal in racing without necessarily being always applicable in any one particular country, open wheeler cars excepted. It is usual for the splitter to be attached to the bottom of the front spoiler and then continue back to form an undertray if required. A splitter by itself is very simple, it is a piece of flat parallel with the ground extending forward from the spoiler and back in some instances. Any substantial continuation back from the spoiler is known as an undertray. Of course all these pieces may be shaped or have attachments or whatever but the basic description still applies for identification purposes. So a splitter can be really simple, the important part comes from understanding that it will generate down force and so will have to be made and attached so it can withstand that sort of force eg a splitter that extends substantially forward may need supporting at the front to stop it from bending down in use. Talking high speed use here not the usual street thing. Hope this helps, terminology seems to be part of the problem when talking aero.

I played seriously with a VG30DET about ten years ago, the most important differences between them and the VG30DETT are obvious visually, there are no real secrets. The heads are good, some say better than the DETT's, the stock exhaust manifolds are also good. The inlet manifold setup is rubbish, mine was all custom including the top feed injector rails which were an absolute nightmare to get right and fit, with that and a GTX35/82R turbo did 420hp at the wheels on 15psi boost. Good luck to anyone who plays with these, they are basically an excellent engine but it's the external detail that will drive you mad if you want real power.

R200 will certainly handle what you propose, makes sure that the axle shafts and bearings are good though. They should be OK but are the weak link rather than the diff.

The undertray is basically just a flat sheet level with the ground, other than the 'kicks' mentioned. The idea was to make something which, no matter what else it did, would not produce lift which is where theory comes in because I don't have any way of testing it other than on the car around a circuit track. In theory it should produce some downforce, reduce drag and assist engine cooling.

Don't know about 3" not mattering Jon, the one on the production car I looked at the other day was more like two inches and I guess it's there for a reason. But I'd agree that it's going to be difficult to work out in practice what effect it will have which is why I'm trying to assess what the applicable theory is, to the part in front of the engine. The two parts in front of the wheels should be kicked up, that seems fairly clear, but when that was done with the previous under tray gravel used to collect there because the kick up stopped it falling out. Leaving part of it flat should remedy that. Anyone else?

Although I'm asking about the back part of the tray which ends at the engine, the bottom of the T, the L and R sides which end in front of the wheels are of interest too John now you mention it. From what you are saying they could be bent up.

Long, flat undertray on the 280ZX V8, connects to the bottom of the front spoiler and goes right back to the front of the engine and right out to the sides in front of the wheels. Looking at it from above it's a T shape with the curved head of the T connected to the spoiler, it's around 1.1m/43" long front to back. Bit hard to take a pic of it fitted so lots of description The question is, should the back of the tray stay flat or should say 75mm/3" of it be bent up or down? Going on what a lot of modern cars have I've bent the back down to about a 45 degree angle, assuming this will help extract air from the engine bay and not have any negative aero effect although the result is an upside down hatch spoiler shape there which may by itself generate lift. But of course there is air flow on both sides of the 'spoiler' which I assume changes things. In all my aero research I've never seen this point discussed so does anyone have some good info that they could share?

First time I've seen this, pity it was not in the Member's Projects section, get a lot more attention there.

No understand.

Amazing what a search turns up

Speaking of autos my track LS3 engined 280ZX is in the process of getting a 4L85E auto tuned for sequential shifting using an aftermarket transmission control unit. It's been a hard and expensive road but for me will be well worth it in the end.

One thing about Nissan is that they don't change bits from model to model unless there is a good reason for it, unlike those Germans who seem to change things just to make life more complicated The kangaroo could mean that the casings were cast in Australia.

400 horses at the flywheel I assume you are talking about John, VG33ET is of course another easy option and it still has that old school cool look.

Otomoto usually imports and sells Japanese Restored brand name composite body parts

There is someone around here doing a LS swap into a Z31.