Thought I'd have a bit of an investigation into the limits of the stock turbo & fueling system in my TT Auto:

 

Result:

 

The map is just a work in progress I created recently. Max duty on the stock 370cc injectors at stock fuel pressure was 94% at the highlighted point with a nice 'safe' AFR of 11.89:1. 1.4 bar was the maximum boost pressure in the mid range, as RPM increases the tubbies cannot produce anywhere near this boost (yes, I know they are being pushed to the ragged edge). Still running stock elbows, downpipes, cats & SMICs. I personally don't mind running injectors at 90%+ duty, I have done it for years on various vehicles, but lower obviously means less heat. Honda run their injectors at 100% in WOT conditions, apparently.

 

I normally run my own cars leaner at 12.2:1 which would give some more headroom with regards to duty and a few more BHP. I have read a lot of reports with people stating stock injectors max out at 14/15/16/17 psi, but they don't. Leaning out under boost with stock turbos at anything less than circa 1.5 bar (bear in mind the turbos will not be producing this at high revs) is due to the OEM ECU programming, not maxing out the injectors IMO.

Edited October 14, 201213 yr by Noz

interesting stuff, so what sort of power is being exported at this level, i wonder how it would compare to say traditional upgraded tubs and injectors. also at 1.4 bar how will the engine cope long term? my other concern would be heat...?

interesting stuff, so what sort of power is being exported at this level, i wonder how it would compare to say traditional upgraded tubs and injectors. also at 1.4 bar how will the engine cope long term? my other concern would be heat...?

 

Bigger turbos & injectors are the way to go for reliable big power but that's a considerable task and costs a lot of time and/or money. Intake air temps aren't going to be great, but I've ran similar-sized turbos at similar pressures and they haven't been too bad. Longevity of the turbos could be a worry, and I wouldn't track the car in this set up. The engine will be fine, they can handle anything a couple of T25s can throw at them. It's all in the mapping :D

 

As for power, no idea. Ran a 110mph terminal at lower boost earlier this year with a full-weight car and generic map I made a long time ago. Probably at the dyno this week, so may stick it on then.

Great info :)

be interested in hearing more on this.. i've done a base set of mods and was considering injectors next, as i'm running 1 bar and didnt want to go over that on the stock injectors. i'm also running the stage 1 chip, but havent had her remapped yet.

 

keep us posted :)

We had a customer once who was running 21psi in a daily driver, bog standard engine, we checked all we could get to and nothing looked or appeared to be upgraded, the car went like a super missile and had no sign of detonation and seemed to lap up the boost No problem, I drove that particular car several times and could not work out how it was running how it did.

 

Later the owner had a small problem and posted up on here how it was running and was blasted for been incorrect and no one believed him, but we had seen it and it was real, a garage owner in Cyprus also came on here years ago and said how they had 500bhp out of a totally standard engine and no one trusted what he said, later on a trip to Cyprus I saw how it was done and its very possible.

 

Jeff TT

be interested in hearing more on this.. i've done a base set of mods and was considering injectors next, as i'm running 1 bar and didnt want to go over that on the stock injectors. i'm also running the stage 1 chip, but havent had her remapped yet.

 

keep us posted :)

 

There's not really much more to add buddy, fact is there is plenty of fueling available for 1 bar. I've run 280-290bhp on the 4 cyl SR20DET with 370cc injectors numerous times, 430bhp on a 6 cyl VG30 will be within reason, and to add a greater margin of safety, no reason why you can't simply fit an adjustable fuel pressure regulator, increase the fuel pressure slightly and map accordingly. I've been running my Auto at a minimum of 1.2 bar since I bought the car in December 2011, nearly a year. It's my daily driver, as well.

 

The maximum output voltage of the MAF in the above log is just under 4.6v, this gives a good indication of the power you can achieve even with the stock Auto turbos.

did you increase the fuel pressure on standard fuel pump? i've recently up'd mine to 1 bar since i got my hks boost controller, and i've set the boost warning to kick in at 1.4 bar. the problem i've got is I dont know how far I can push it before she'll go bang as I had a rotary before and was terrified I was going to blow it up! (thankfully, it never did :) )

It's running the standard fuel pressure regulator & standard pressure.

 

I would never let a car boost to 1.4 bar unless the ECU is running a suitable chip.

We had a customer once who was running 21psi in a daily driver, bog standard engine, we checked all we could get to and nothing looked or appeared to be upgraded, the car went like a super missile and had no sign of detonation and seemed to lap up the boost No problem, I drove that particular car several times and could not work out how it was running how it did.

 

Later the owner had a small problem and posted up on here how it was running and was blasted for been incorrect and no one believed him, but we had seen it and it was real, a garage owner in Cyprus also came on here years ago and said how they had 500bhp out of a totally standard engine and no one trusted what he said, later on a trip to Cyprus I saw how it was done and its very possible.

 

Jeff TT

 

Dont shoot me down on this as the info comes from the US and we all know about there BHP talk, but been told that the VG30DETT in stock form can handle up to 600bhp as long as its well maintained. and that is the key, it needs to be well maintained.

 

The one upgrade they say to do if going down that route though would be to change the big end bearings for race spec ones as the OEM ones are the weak point in the engine, and seeing people throw con rods due to engine knock id have to agree.

 

Obviously a decent map as well.

 

How reliable this information is i dont know.

I can't see any reason why a decent turbocharged Nissan (Japanese in general) engine can't make double the factory figures with a large enough turbo, suitable fueling, intercooling & mapping. Done it myself with a few cars.

WOW, very thanks for the information,

 

Thanks Noz,

For those that don't know, I did snetterton time attack with a stock short block, giving it death, revving to 7600rpm, key is having a good map (base boost, 420rwhp)

 

However, I'll also say, back in the day, when I had stock inj, it was leaning out at 1bar. It was at spool up it was struggling, not top end so doesn't surprise me if you have a good map it might be alright. This will be a case by case thing and will depend on how efficient the setup is. An efficient setup will flow more air at less psi, so please by careful everyone

For those that don't know, I did snetterton time attack with a stock short block, giving it death, revving to 7600rpm, key is having a good map (base boost, 420rwhp)

 

However, I'll also say, back in the day, when I had stock inj, it was leaning out at 1bar. It was at spool up it was struggling, not top end so doesn't surprise me if you have a good map it might be alright. This will be a case by case thing and will depend on how efficient the setup is. An efficient setup will flow more air at less psi, so please by careful everyone

 

What I got from various logs over the year was that they lean out in the mid range at WOT, but this is only due to a certain parameter in the ECU programming. Top end was marginal, but safe. Mid range it was dangerously lean, most notably as the 'box shifted into top. But it's all down to the mapping, the stock fuel system at standard fuel pressure is adequate on the Autos for over 1.4 bar. Just... No problem at all at 1 bar, though. The stock ECU uses O2 feedback quite far into the spool-up (transistonal) areas of the fuel map. I'm not a fan of this, it's much better to be around 12.5-13.5 coming onto boost than 14.7:1 IMO. I've found a lot of chips retain this feature, it's not ideal.

 

Without good mapping and monitoring of AFRs, it's not possible to run decent boost safely. Not forgetting the timing side of things, I also use cold-running plugs and know that everything is spot-on, especially base timing. I can't drive a modified turbo car without my wideband, it's a gauge every car should have. Plus I have a finely-tuned ear for detonation (and det cans) :biggrin:

 

Definitely don't let your standard or 'Stage 1' car hit anywhere near 1.4 bar and expect it to survive very long!

okay so in english, stock injectors, stock turbos, a boost controller, JWT or John DIxon chip , mongose exhaust , sponge air intake , standard SMIC, strong engine , well maintained , what is the MAX boost one should run, i have always been told , and respected 1 bar.

okay so in english, stock injectors, stock turbos, a boost controller, JWT or John DIxon chip , mongose exhaust , sponge air intake , standard SMIC, strong engine , well maintained , what is the MAX boost one should run, i have always been told , and respected 1 bar.

 

Simple: Depends on the chip. Nothing more, nothing less. They will have specified a boost level and it should be stuck to.

I'm in full agreement with this, the problem is that all cars are slightly different. However, if you know exactly what you're doing and map the chip for your car then there is a lot more to be gained than from a 'standard', 'safe', tuned map.

So when I want a chip or map whats the best way forward? With a tock engine and syockish tubs.

So when I want a chip or map whats the best way forward? With a tock engine and syockish tubs.

 

It really depends on what you are after. There are plenty of options though, even having your car "remote-mapped" from logs, which sits part-way between a generic chip and a live map on both the road and dyno. The downside of this is optimising the timing map. You need the dyno for that. If you're looking to push things, find a tuner you are happy with and speak to them about it. If you just want to run 1 bar on a generic chip, it's just a case of fitting said chip, upping the boost and forgetting about it (assuming the chip contains a good map).

 

There are thousands upon thousands of cars out there running generic maps. You can't beat a custom tune though, and when you push things, it's a requisite.

Id like to top over 400 at some point but I think realistically atm 350 is more realistic financially.

Id like to top over 400 at some point but I think realistically atm 350 is more realistic financially.

 

Decent chip will get you 350bhp with ease. For 400, I would personally have it mapped on the road.

Interesting info Noz.

 

Can the standard ecu map be tweaked whilst on the rolling road to adjust fuelling and timing to produce more power or is an uprated map a prerequisite?

Interesting info Noz.

 

Can the standard ecu map be tweaked whilst on the rolling road to adjust fuelling and timing to produce more power or is an uprated map a prerequisite?

 

Other than a piggy-back solution (Unichip, SAFC etc), the only way to adjust fueling & timing in real time is with a mappable ECU set-up. NIStune, for example is the most common way nowadays when working with the stock ECU, but you can also use EPROM emulators (which is what I use along with NIStune software for my Zed). These turn a stock ECU into a mappable ECU. An uprated map contained on a replacement chip cannot be adjusted on the rolling road, the same as a standard chip can't.

Nice one thanks

I have new tubs new hks air filter ( huge) and new huge FMIC. Also have an EBC and now looking to have it set up. Maybe i should invest in a fuel reg to. Anyway where do you sugest i get car set up. dont what else the car has in regard to chips ecu ect. Any ideas?

Horsham developments are great at mapping nissan ecu's and can also fit nistune boards