John Dixon

There seem to be a few different approaches now. Saw some drawings of the nissan system ages ago and from memory it uses followers on a moveable shaft as part of the linkage presumably to give variable lift and duration, can't really remember exactly how it looked. The multi-air has a cam with basically the biggest profile that doesn't make the valves hit the pistons then uses hydraulic actuators between the cam and the valve to control the valve movement. Pretty sure they even do multiple valve openings at low revs to give higher velocity / increased swirl. Didn't honda do a V12 at one time in some limos too, wonder if that had VTEC?

Nissan V8's after the Y series all had VTC on them, even my 1992 VH45DE. The newer VK ones they do have continually variable cam timing on both sets of cams I think. Can't remember the model but it'll be VK50xxx, use in the new infiniti saloons, very nice bit of kit. Its kinda odd how Honda sell so much on VTEC yet most manufactures use similar technology. The new fiat/alfa multi-air engines are a great bit of tech too, one of those ideas so simple you wonder why nobody has done it before.

Its still an engine load cut regardless of what sensor its based on. Air flow is a far more fundamental measurement of engine load than boost alone. If you swap the cams on and TBs on a stock VG30DETT then you’re going to see far higher air flow rates at the same boost pressure on a stock engine. In that instance the TP based cut would save the engine, a boost cut would not. Prone to what sort of variation exactly? Other that variations in air temp which are accounted for by the fact it’s a MASS air flow meter its only metering air, it doesn’t see any real turbulence effects unless you fit a bad filter design. At the end of the day, it’s the ECUs primary load sensor, it relied on entirely for the operation of the engine. If it was prone to variation then the engine would not run properly. Its no mistake that every modern production car uses AFM as their load sensor, it’s the only way to get the accuracy required to meet modern emissions standards. That’s only an assumption. Its equally valid to assume that the engineers simply chose to implement a load cut strategy that would protect from a wastegate fault or split line which would make Nissan look bad or lead to a warrenty claim (which the TP cut does do) and didn’t worry about people doing unsupported mods. Its also not hard to believe that with the 280bhp ‘gentlemen’s agreement’ in place at the time the 128 TP value is to allow some gentle tweaking - otherwise why have maps upto ~100TP/13psi in the stock ECU. FYI TP=160 is ~18psi on a stock(ish) setup so its well below that. Its very repeatable too, if you hold the load on the dyno you can set it accurately on a custom map. Do you not think given the effort on the rest of the ECCS system and the lengths they went to (even a fuel temp sensor!!!) that if a MAP sensor was necessary it would have been fitted? The ECU has spare 0-5v inputs and there’s already a MAP sensor there for the boost gauge which could have been used for almost no cost. Sorry, but that’s completely untrue. Any mods that significantly change the VE curve of an engine render a boost based cut meaningless unless the ECU is remapped. An engine running de-restricted intakes, TB’s bigger turbos and a good exhaust would blow long before it hit a 15psi boost cut that was perfectly safe/effective on a stock engine assuming the maps were unchanged, the dynamic CR would be way higher and timing requirements would be for much less advance. On the emeralds I fit I use alpha-N / MAP load sensing and do use a boost cut but that’s only relevant when the engine setup is completely unchanged. With a MAF based system it will at least sense the extra air flow and cut the ignition. To be fair, we’ve kinda gone off piste here and what I’m sure your experiences will back up is that almost all blow-ups just come down to bad modification and / or not sorting the basics out first!

It does exist, its just implemented as an air flow cut not boost but as the table is air flow / rpm based its close enough to the same thing. It definietly works, you can adjust it on the dyno and see the results. Normally set it to 110% of max TP on full boost at each rev break point. On stock its set pretty high. Suspect when people have blown them then there may be other underlying problems or incorrect timing etc. etc. or they have a JWT or similar ECU with the cut removed completely.

TP Calculation is based on MAF voltage corrected for sensor curve then with several mods for throttle enrichment etc. Essentially though its air flow.

Odd, all the values in the TP limit table are the same on all 8 bit TT Stock codes that I've ever seen @ 128.

Sounds like you've got an ignition issue and its struggling to spark across the dense mixture - maybe new plugs needed as a first check. Either that or your ECU is hitting the boost cut if its stock.

I did a few of these years ago and as far as I know they're still going. An absolute bugger to solder though!

Happy birthday Mike!

If you set all the corrections in the SAFC to 0 and just use it to add the MAF signals (assuming you have 2 MAFS) then it's fine. If you only have one MAF then yes, bin it.

Cheers all! Glad you're happy with it mate. Nice to see a good, well looked after Z too :)

If you're stuck I've got 2 old subframes and you can have the ones from there, just can't make any promises on time I'm afraid as they're down the pit in the garage and I need to move about a million things to get to them. Have you tried Jeff, he must have hundreds of old ones about? Worst case any machine shop could knock you some up if you give them the dimensions.

Hi Dewi, will do mate, will do it tonight. Cheers

Or option 3 which I'm doing: Skyline GTR diff. It's an R200 so fits the NA subframe and gives the weight saving. Is a 4.1 ratio like the NA BUT has all the 6 bolt big spline flanges like a TT R230 so you can use the bigger driveshafts AND is a better plate diff rather than viscous. I'm 1/2 way through doing mine so will let you know how it goes (don't hold your breath though, could take me a while!!)

Yes, currently I just wired it to the gearbox speed sensor so it can do gear detection (speed vs RPM) but for TC etc. it will need all 4 ABS sensors wired up.

Its a standard nissan part on manual cars. Just need to get one off a breaker is easiest. The emerald will have launch control too so may be easiest to use it for TC/Launch too maybe then its all integrated into one place. Also, with your gearing as it is, we can do gear specific boost control to limit boost in lower gears if you want?

Glad you had a good day down there Bazz, Dave really is a top bloke. Once you get the fuel pupm sorted we can even out the boost dip in the higher boost setting which will remove the torque dip too. Full throttle shift is ready to go but you need to fit a clutch switch as your car didn't have one. Did the other guys tidy up the cables etc. for you yet? How is the drivability?

No prob Bazz. Car is going to be stunning when it's finished. Love the genuine, metal, strosek kit. Aaron, haven't forgotten you either mate, just trying to juggle 75hr working weeks and house renovation with the dyno guy's timetable!!

They all do pretty much the same job really, just comes down to cost, features and local expertise. There's not much wrong with the AEM other than the sensors are usually miles off calibration and the mapping software is awful. It's a re-badged GEMS unit. I use emerald for a few reasons but mainly because the service is 2nd to none and price-wise its hard to beat. Think that if you go to emerald for the mapping, you have access to the people there who design and build the ECUs! For example, they have now done a firmware to read the 300zx CAS directly after I nagged them for a while. Another BIG plus for emerald is fixed price mapping, £275 to map it is cheap and Dave will usually sort out other issues too without charging extra. In the past he's even machined up new spindles and all sorts for customers.

Best bet thees days particularly if you're having a re-map is to use a ford lightening MAF. Flows enough for 700bhp, is cheaper than one nissan unit and no low speed issues like with the doolz style intakes.

Hi James!

Friday on here has a pretty nice one for sale. He's not really on the forum much but if you drop him a PM he'll probably respond.

I've got a VH45DE in mine, if you want to have a chat about it drop me a PM. It's not a job for the feint hearted!

Not sure if the AEM recognises the 36-1 (Ford) pattern but if it does then yes, it would work OK. It's a bit of a bugger to change, you've just got to be carefull with it really and the screws that lock the disk in place are a bugger.

Stick with the 550 for your application mate, 740s just overkill and likely to be a very slightly worse idle.