Right, thought I'd start this. As some of you may know my cars a bit broken at present and I have a pile of parts ready to fit that gets bigger without it making its way to the car.

 

So lets start with what's up with the engine. Myself and gaz pulled the engine about two winters ago now, as one of the turbo's had failed. Compression was tested at this time with a very even 170psi across the board. Pulling it all apart we found a multitude of issues, egr hanging off causing an exhaust leak old sockets rolling about etc etc. We took that time to replace every damn crusty water and vac pipe and delete just about anything I considered a waste of space.

Water plenum bypass,

EGR,

AIV,

PRV,

Cruise control,

Aircon,

Think that's all. The turbos were rebuild by myself and for the first 50-100 miles things were bob on and I didn't give it too much stick. The first couple of pulls it detonated, new plugs, reduced the issue but it still did it a bit. Changed to a smaller gap and great the det was gone. The car was pulling very well at this point with virtually no lag and was dyno'd at 289hp bone stock, no extra boost no chip. Not bad for an old auto engine. Sadly it had started to smoke on over run, I assumed id cocked up one of the turbos during the rebuild. So I had been putting it off for months, well actually years now to pay out for brand new turbos. Anyways as the tax ran out I thought id do some more inspecting as the symptoms just didn't fit the pattern of failed turbos. The first thing I found was that lovely even compression was no more, cyl had a rather lame 115psi. Cue further inspection to work out exactly what block I had, manual/auto etc I assumed it was auto. That's when I found this...

That head casting reads R-10Y, wtf is that I thought. It's supposed to read 40P this was one of those penny drop moments. The piston crown sealed that moment of realisation and many dots connected.

That's right its an NA, 30p pistons are NA and 30p1 are TT defiantly no 1 on that code. Turns out r-10y is the later spec NA head aswell, so yeas 100% an NA block. Now this engine was fitted by a garage 4 years ago a few months into my ownership and we wont go into that too much but it wasn't a great experience and it transpires it was worse than I first thought. Anyway whilst they refused to reimburse me for that error, a good will gesture was sent out to me in the post of a few quid.

So a replacement engine is going to be sourced and fitted this winter. More of that and what's happening to the current late spec NA block.

 

So now more about that shelf of parts. I purchased last winter a full rear subframe assembly off Jaffa, the one off his time attack car. Loads of goodies already polybushed to death etc. So I stripped it down to bare metal and started painting it all with a few coats of lovely hammerite. This is how it stands at present;

So this winters aims are.

Remove front and rear bumpers, re underseal all of that and rip out and guff.

Delete HICAS system

Reloacte PS reservoir and fusebox

Switch over all suspension to new units from the shelf

Fit 354mm diameter brembos

Change engine out and preform various mods

It sounds like a lot, but hey winter is along time. Don't expect it to be coming through thick and fast. Im lazy haha

42 minutes ago, Bones28 said:

I looked at the Z350 but insurance and road tax were very expensive, got a XK8 instead. A 2014 Z370 is £710 a year road tax.

Something worth noting that. I think there’s two different tax brackets for the 370z depending on age, some cheaper than others. 

Glad to hear the modern day Z retains the old school charm and the NA power delivery is something special in itself. Saw a Nismo one driving in front of me and they do look pretty mean and well stanced. Good luck in your search and on the sale of your current Z. 

I’ve always been tempted by a Nismo 370 but I’m just not a fan of the interior.

On 27/06/2024 at 20:00, Joely P said:

I’ve always been tempted by a Nismo 370 but I’m just not a fan of the interior.

The series 1 I agree. The series 2 has the Recaro C1s or whatever they are called which I like a lot. 

On the tax/insurance aspect the Vette is much cheaper. Tax is almost half, for almost twice the displacement:lol:

8 hours ago, Stephen said:

On the tax/insurance aspect the Vette is much cheaper. Tax is almost half, for almost twice the displacement:lol:

Saw a YouTube review of 370’s yesterday and they said the post 2017 or 2018 cars have the cheaper tax bracket around £190 I think. Downside is those newer ones are in the £20k  + region. Shocking that most of them are £700+ tax!! 

Had the car on the Dyno today. Mix bag really. I found a fault, the boost controller was jamming so the first couple of rolls the car was pushing about 20-21psi, luckily all quite safely. With the controller disconnected a base line was set.

First run we ran on wastegate pressure, about 5psi. So less than stock boost, safety boost basically, and she made a very healthy 286bhp more than it should. 

Then the boost was set to 16psi and we had a roll. Peak torque and hp arrived around 4500rpm at 320bhp. The car was running rich AFRs at this stage and no detonation but the car wouldn’t continue to pull progressively through the curve to produce more power into the 5k, 6k range. Why I’m not sure but if it had continued to build power at the same curve it would have produced about 350 maybe. 
 

So there lies the conundrum. There’s plenty of boost left, plenty of fueling left but we’re out of puff by 5k. On the positive a 35 year old car makes more power than new in virtually limp mode and there’s a very solid mid range performance. 

The question really is why doesn’t it make more power and what on earth will I do from here because the road to more is an expensive one, especially when my intention is to sell. Perhaps I should leave it as a solid car at near stock power and leave those questions to the next owner. 

What power mods do you have that make you expect much more? When you say plenty of boost left, if those are stock turbos 16psi is the useful limit of those really. While you can make them boost past that, you won't find much power. Similar with the stock injectors, they start maxing out around those boost levels. 

In near stock form, it does run out of pull at the top end. Looking back at my old dyno graphs and its pretty flat at the top end, like you describe.

Your peak power is a little low but that could be any number of things that are not optimal.

Just now, Peage said:

What power mods do you have that make you expect much more? When you say plenty of boost left, if those are stock turbos 16psi is the useful limit of those really. While you can make them boost past that, you won't find much power. Similar with the stock injectors, they start maxing out around those boost levels. 

In near stock form, it does run out of pull at the top end. Looking back at my old dyno graphs and its pretty flat at the top end, like you describe.

Your peak power is a little low but that could be any number of things that are not optimal and/or a dyno that reads lower than others. Can you post the print-outs?

 

It’s all been done to death to be honest, I can’t really be bother to go over it. There’s so little experienced and skill on the tuning side of these cars and we go round in circles. Owning a Z is a different path, the different path is never the easy path. You have to be prepared to trail and error things and seek out specific people and have trust in them and even that isn’t constant as the go person is often like an annual bedding plant. 
 

Realistically to make a worthy gain from here I need a custom tune and that realistically means at the very least going Nistune. Of the limited amount of people prepared to do that for the board and map it’s a grand, which is a non insignificant amount for a gain of a 30-50hp and no real safety benefits. Nistune is so basic now compared to stand alone stuff which would not only offer greater power but greater safety for the engine. If you’re in for stand alone then running stock turbos and injectors is a waste of the ECU. 
 

I’ve been doing some thinking after the events and I felt pretty despondent, still do, being frank it’s a miracle I found enough motivation to reattempt the MOT this after after the first one being a cock up. That lack of motivation in the main Is due to personal things. Whilst for a while I thought my lack of ability to make a decision was down to not finding the right car, I think the real issue is I’m just not that interested in cars anymore. 

On 02/07/2024 at 19:33, Stephen said:

Had the car on the Dyno today. Mix bag really. I found a fault, the boost controller was jamming so the first couple of rolls the car was pushing about 20-21psi, luckily all quite safely. With the controller disconnected a base line was set.

First run we ran on wastegate pressure, about 5psi. So less than stock boost, safety boost basically, and she made a very healthy 286bhp more than it should. 

Then the boost was set to 16psi and we had a roll. Peak torque and hp arrived around 4500rpm at 320bhp. The car was running rich AFRs at this stage and no detonation but the car wouldn’t continue to pull progressively through the curve to produce more power into the 5k, 6k range. Why I’m not sure but if it had continued to build power at the same curve it would have produced about 350 maybe. 
 

So there lies the conundrum. There’s plenty of boost left, plenty of fueling left but we’re out of puff by 5k. On the positive a 35 year old car makes more power than new in virtually limp mode and there’s a very solid mid range performance. 

The question really is why doesn’t it make more power and what on earth will I do from here because the road to more is an expensive one, especially when my intention is to sell. Perhaps I should leave it as a solid car at near stock power and leave those questions to the next owner. 

Can you post a photo of the dyno graph so I can see what it’s doing at the top end…

 

gut instinct says VTC isn’t disengaging and it’s stuck with too much valve overlap

Higher figure is at 16psi, lower at 5psi 

A recent shot on the drive. 

Shame we can't see the drop off up top as they pulled out of it around 6k RPM. Did they give you a corresponding AFR trace? Just wondering if you have a boost leak that is only happening at higher boost levels. If it starts leaking boost you will see the AFR go richer at that point. 

There was one present at the time but it’s not on the print out. However there’s an old graph from a few years back, the car is in the same state as then having covered very few miles 1000 would be generous. The only difference really is the plug gap, decreased from 1.1mm to 0.85mm and a pair of Godspeed SMIC. So it’s pretty relevant data and what I saw on screen reflected the reading on this. I have done a boost leak test and didn’t find anything. 
It does run very rich as soon as it starts boosting. The chip is one that TurboNoz made as a generic. 

8 minutes ago, Stephen said:

The chip is one that TurboNoz made as a generic.

You might want to swap that out for a "known" map Stephen.

22 minutes ago, AndrewG said:

You might want to swap that out for a "known" map Stephen.

Like what though? The JWT ones and variants therein are all pretty poor. I could potentially get something from the US but I’d need to be careful about what fuel is mapped for etc. I have had a chat with Horseham Developments but I’d need to go Nistune. 

2 minutes ago, Stephen said:

Like what though? The JWT ones and variants therein are all pretty poor. I could potentially get something from the US but I’d need to be careful about what fuel is mapped for etc. I have had a chat with Horseham Developments but I’d need to go Nistune. 

I’ve seen consistently good reviews of the Specialty Z chips, from UK owners. From what I read, they appear to be the best of the bunch, as SZ have so much experience in tuning Z’s, they’re usually all you need for your level of tune/power. 

I've posted this up for reference:

https://www.specialtyz.com/products/sz-ecu-chips-or-nistune-file

I plan to go with a SZ map. I'm pretty sure that Joel is running with a SZ map for his car.

Edited July 10, 20241 yr by AndrewG

I’ve pinged them over an email and asked some questions. In all fairness, I drove the car last night and the mid range pull, especially since re-gapping the plugs is great, very smooth and responsive.

I ran an SZ chip when I had a near standard setup like yours and made 330hp initially, finding and fixing a boost leak at higher boost levels, like I mentioned before, it went to 360hp on the same tune. All of them run pretty damn rich though, just the nature of using a safe general chip tune vs a custom map. That being said, those Noz maps are apparently terrible so might be worth switching regardless, if only for safety reasons and not power. 

Is that old graph showing the same flatline you are concerned about up top? It looks basically like it should to me. On standard setup mine had the same plateau upper mid range and then started to peak again beyond 6k - which is why I said it was a shame your latest graph doesn't show beyond 6k on the high boost run. That flat line in the middle does not look too unusual to me when compared to my old graphs. If you are expecting a linear curve - you won't get one.

I'd say swap the chip for safety, if it happens to net you more power, lovely, if not - just enjoy the car and double check the mechanicals dependent on how much effort you're willing to put in I suppose. 

 

As it happens I was passing Horsham Developments so I popped in and had a long chat with Jez about the options they would recommend. I haven’t had anything back from SpecialityZ yet. I may just go Nistune and then the ability is there for future wether that’s me or someone else and the tube will be far better than any generic chip. 

Keep us posted - would like to go Nistune at some point too.

25 minutes ago, Peage said:

Keep us posted - would like to go Nistune at some point too.

What are you running now?

Somethings deffo not adding up here, there no mechanical reason why it shouldn’t be revving up to the factory 7200rpm rev limiter. It has to be electronic systems based issue. But for the sake of being thorough, I’d do a compression and leak down test to eliminate any potential issues in the combustion chamber (I’m not suspecting any, but better to be safe than sorry and know for sure!)

the fact the dyno sheets don’t show what happens after 6200 rpm doesn’t really help with being able diagnose the issue.

Did the tuner give a reason as to why he didn’t Rev it all the way out to the limiter?

I don’t think the issue is VTC as I originally thought. The engine would still Rev out but it’s peak power would be made at around 5000 rpm and the torque curve would drop off more dramatically than that.

spark gap shouldn’t have made the slightest bit of difference at 16psi of boost, even at 24psi I ran NGK supplied gaps with no issue at all. Which makes me think ignition system based issue producing a weak spark

Is it still on a S1 PTU? Any sign of any misfire no matter how minor?