Took some time out last week from work and managed to take my 300 to Bristol to see Jimmer of PowerZed

 

The plan was to try and get a bit more horse power out of the old lady as she was mostly stock when it came to the internals,

 

Jimmer fitted the Greddy EBC and removed the ECU and put in a new one with a map for stage 1, the car now feels a lot more responsive and boosts up to 13.3 psi the horsepower gains where tangible with around 350-380bhp expected (will dyno her at some point in the future to find out).

 

Next on the list of modifications will be a sports clutch and flywheel most probably towards the end of the year as well as brake pads,

 

I must say I found Jimmer to be an incredible specialist and a true gentleman, I can’t wait to take the car back to him once again in the near future,

 

Thanks Ian. The glove box is an obvious place but, much like yourself, I would forget about it. I have thought about mounting it in the lower radio/CD player hole and creating a cover plate made from the OEM CD player to hide the EBC day to day, then I can remove the cover when I feel like a more spirited drive is in order.

There’s the point of contention. I’m saying he doesn’t need bigger injectors for 17 psi to be safe, just a suitable map, you believe that stock injectors cannot supply enough fuel for that boost level. Am I interpreting our difference incorrectly?

 

I would side with this statement.

 

I would argue that at that boost level (16PSI+) on stock turbos, you're at or beyond their max duty cycle; a good map is not going to help if you go beyond that threshold. You're running close to 80% at 14PSi on 370cc injectors which is perfectly safe however when you're up around 16/17PSi, then you're reaching 100% duty which is not devastating in its self, however you have no margin for error, potentially heat issue and you have less control over the injector at 100% duty. Whilst you cannot really accurately control how much air your engine is consuming, you can meter the fuel very precisely, however at 100% duty cycle, you don't have that same level of control, it's effectively wide open.

 

It's just too much of a gamble couple that with the reliability of older pintle style injectors' coils, it's just not worth running reliably on old low-flow injectors irrespective of how good the map is (a good map is key too, I’m in no way disputing that). Sure, fitting newer style injectors would solve the reliability issue, but it's prudent and I’d say a necessity to fit higher flow injectors (with good map) when hitting that sort of threshold if you want to maintain reliable engine and I can’t imagine anyone would argue with that.

 

Almost everyone would rather run unstressed high flow injectors+map than running stressed low-flow injectors+map. There's also the argument that the lower the duty cycle the cooler the injectors run, the more they have to work, the hotter they get, the hotter they get the quicker they can fail.

 

The most cost effective injector upgrade is the 740cc upgrade. 555s are now pinteless 615s which are fine, but there’s little cost difference. That’s where the context was lost I think.

Ive got one in my glove box, its such an unhelpful place ive never looked at it. I sometimes think i should see what it shows and learn what it does, but then i forget its there again

 

:lol:

 

Same! Mine's in the din cubby.

Thanks Ian. The glove box is an obvious place but, much like yourself, I would forget about it. I have thought about mounting it in the lower radio/CD player hole and creating a cover plate made from the OEM CD player to hide the EBC day to day, then I can remove the cover when I feel like a more spirited drive is in order.

 

My HKS controller lives in the glove box fixed to the top surface. Set to 1 bar maximum boost, I treat it as a "fit and forget",

so don't need to see it when driving. It also reduces the temptation to play around with settings...

My old one did have a nice warning tone if it was over boosting on cold days. Can you hear it from the glove box though?

My old one did have a nice warning tone if it was over boosting on cold days. Can you hear it from the glove box though?

 

It will generate a tone which I doubt I would hear, but more importantly the controller returns the boost level automatically to the stock level

and stays like that until the throttle is lifted. That I would notice, but in all the years the HKS has been fitted it has never kicked in.

 

Why would your old controller over boost on cold days?

With regard to injector sizing for boost, the maths don’t lie.

 

370cc @ 43.5psi injectors x6

2998cc 6 cylinder engine

Boost pressure of 14.5psi

Maintaining AFR of 11.5/1

 

At 7000 rpm duty cycle is at 95.25%

 

 

The general consensus for ROAD based cars is duty cycle shouldn’t exceed 85%. Whilst the flow-pressure characteristics of the OEM pump mean that At 60psi absolute pressure it still flows a sufficient volume of fuel that reduce the risk of running a higher duty cycle for a VERY short period of time, running above 85% does mean that you’re eating into a margin of safety that is there to account for variances in atmospheric conditions including both air and fuel temperatures. To be able to flow enough fuel for more than 14.5 psi, you would have to raise your base rate fuel pressure to effectively force more fuel out of the injector at any given duty cycle. The risk of this is that as fuel pressure goes up the amount of fuel the pump can flow goes down.... you then run the risk of running lean by way of insufficient fuel supply from the pump.

 

When you then factor in that the early style pintle capped injectors are at least 26 years old by now, and simply don’t spray as cleanly or consistently as the newer style pintleless injectors, I would STRONGLY advise changing to the new style Nismo 740cc injectors to ensure safe running at anything above the boost levels Jimmer as set for you.

Edited July 30, 20196 yr by nickz32

I’ve never seen the logic in having a boost controller that you change dependant on the weather, I say leave it as it is and control it with your right foot! I’m in the fit and forget gang, mine is in the glove box.

 

Interestingly, regarding the discussion/row/handbags/other dimension of this thread, when Jim fitted Z1 GT525 turbos to mine with no other mods (excluding filter and exhaust that were already fitted), the duty cycle peaked at 95% at only 9PSI in the rolling road. How does this work for your calculations Nick?

With regard to injector sizing for boost, the maths don’t lie.

 

370cc @ 43.5psi injectors x6

2998cc 6 cylinder engine

Boost pressure of 14.5psi

Maintaining AFR of 11.5/1

 

At 7000 rpm duty cycle is at 95.25%

 

[ATTACH=CONFIG]117833[/ATTACH]

 

The general consensus for ROAD based cars is duty cycle shouldn’t exceed 85%. Whilst the flow-pressure characteristics of the OEM pump mean that At 60psi absolute pressure it still flows a sufficient volume of fuel that reduce the risk of running a higher duty cycle for a VERY short period of time, running above 85% does mean that you’re eating into a margin of safety that is there to account for variances in atmospheric conditions including both air and fuel temperatures. To be able to flow enough fuel for more than 14.5 psi, you would have to raise your base rate fuel pressure to effectively force more fuel out of the injector at any given duty cycle. The risk of this is that as fuel pressure goes up the amount of fuel the pump can flow goes down.... you then run the risk of running lean by way of insufficient fuel supply from the pump.

 

When you then factor in that the early style pintle capped injectors are at least 26 years old by now, and simply don’t spray as cleanly or consistently as the newer style pintleless injectors, I would STRONGLY advise changing to the new style Nismo 740cc injectors to ensure safe running at anything above the boost levels Jimmer as set for you.

 

Has your calculation taken into account that fuel pressure at 14psi isn’t 43.5psi?

Yes mate, 1:1 rising rate so @14.5 psi boost fuel pressure is at 58psi

I’ve never seen the logic in having a boost controller that you change dependant on the weather, I say leave it as it is and control it with your right foot! I’m in the fit and forget gang, mine is in the glove box.

 

Interestingly, regarding the discussion/row/handbags/other dimension of this thread, when Jim fitted Z1 GT525 turbos to mine with no other mods (excluding filter and exhaust that were already fitted), the duty cycle peaked at 95% at only 9PSI in the rolling road. How does this work for your calculations Nick?

 

Where did you get that duty cycle reading from whilst on the rollers?

I’ll add a quick footnote. As a general rule of thumb the cc Number if the injectors is roughly the maximum HP the injectors will support safely, so 370cc roughly supports max of 370hp, 550cc=550hp max etc etc etc. Obviously there are lots of other variables to take into account, but as I say, it’s a good rule of thumb

Why would your old controller over boost on cold days?

 

I couldn’t even pretend to know but on cold winter days the boost pressure would go up to my set limit and the EBC would stop it going any higher.

Thank you all for some great advice and suggestions, I'll definitely go for the Clutch upgrade first, and then save up for the 740cc Nismo Injectors as a luxury extra,

For me having gone from a stock 300bhp (ish) power to the higher boost setting of 13.3psi and map is plenty fast (for now) :)

Also I definitely want to bring the car to the next Club meet or AGM and meet everyone face to face,

Yes mate, 1:1 rising rate so @14.5 psi boost fuel pressure is at 58psi

 

Sorry, yeah you did say that.

I’ve never seen the logic in having a boost controller that you change dependant on the weather, I say leave it as it is and control it with your right foot! I’m in the fit and forget gang, mine is in the glove box.

 

Interestingly, regarding the discussion/row/handbags/other dimension of this thread, when Jim fitted Z1 GT525 turbos to mine with no other mods (excluding filter and exhaust that were already fitted), the duty cycle peaked at 95% at only 9PSI in the rolling road. How does this work for your calculations Nick?

 

Obviously the GT525s are moving more air at 9 psi than a T22/5 at a similar pressure. Which creates a leaner ratio. As nicks said, you need more information to answer that.

I’m in a slightly more patient mood today so il explain what I was on about in respect to the injectors abilty as such. The numbers below are theoretical and you can’t expect that x = y exactly every time it’s merely a guideline.

 

The fuel map, on the ECU, has a margin for error. That’s about 20%. Thus doesn’t allow you to add more than the margin within that map. Most chips etc are an extrapolation of the stock map. As per the stock map and iterations of it;

3 bar fuel pressure @ 100 duty is 370cc, sufficienct for 370hp @ the fly.

This is a smart thing for a manufacturer to do to a car for a world market.

 

If we lift the restriction of the ECU so that 100% duty is 100 of total fuel delivery, with no redundancy or margin for error, the injectors can flow;

3 bar fuel pressure @ 100 duty is 370cc sufficient for 425hp @ the fly.

Of corse this is a silly move, no error compensation and everything flat out.

 

The total flow ability for 425hp is limited by the safety margin, which conviently lands us at 370hp at the fly with the stock margin for error. Injector size is equal to peak fly HP. As far as the ECU is concerned we are alt 100% duty but we’re not we're at 85%. So, for example we lift the stock ECU restriction so 100% flow is 100% duty and do not run past 90% duty that gives us 10% margin for error, not enough for a manufacturer but for a custom map, that would be “ok”.

 

3 bar fuel pressure @ 90% true duty on 370cc injectors is sufficient for 381hp @ the fly.

 

So 17 psi on stock Turbos is about 365hp @ the fly.

For a 90% true duty cycle you’d need 355cc of fuel per cylinder per minute.

So as you can see @ 365hp your under your safety margin by a fair way.

At this point you’d be pulling about 65psi on the fuel supply to supply the correct fuel pressure.

 

At this point the factory knock sensor became useless a fair while ago, the factory boost gauge has been off the clock since lunch time and o2 sensors have quit. The only thing looking after things is the ECU with all the processing power of a SNES your passenger is stood on. This is true wether your at 12psi on 370s or 21 on 740s and a crap chip or poor mechanical health you will kill it.

 

If you’ve got money burning a whole in your pocket, for what 740s cost to instal you’d be better off buying nistune and an AFR or better yet a stand alone with failsafes.

 

In short, in my grumpy opinion, 16psi on the RIGHT chip will net you about 365hp and less than 90% true duty.

For a 90% true duty cycle you’d need 355cc of fuel per cylinder per minute.

 

That doesnt ring true Thats 2.13 litres per minute for the Zed Engine.You wouldn't get very far at that rate, about 32 minutes driving if the tank was full !

Edited August 4, 20196 yr by TonyB

I would always upgrade injectors, even if they are not running at near maximum duty it makes sense seeing as they are 20-25+ years old to replace them along with the fuel pump for safety and longevity reasons.

to move from the theory to practice, just connect Conzult or NDS and read the Duty Cycle in real time, I can not try with my Z

But, I have an example with my 200sx S14, engine SR20DET,

 

it was equipped with a complete exhaust system without catalyst, fuel pump walbro, flywheel 6kg, intake filter Apexi, intercooler Silvia S15, delete EGR, spark plug irridium IK24, Boost controler Greddy profect b2 with 15PSI of boost, injectors OEM 370cc, a Eprom Horsham.dev to configure the set

 

With 15PSI, my injectors OEM 370cc had a duty cycle between 90 and 95%

Where did you get that duty cycle reading from whilst on the rollers?

 

It was just verbal advice from Charlie at SRR, I didn’t think to ask how he knew at the time.

 

to move from the theory to practice, just connect Conzult or NDS and read the Duty Cycle in real time, I can not try with my Z

But, I have an example with my 200sx S14, engine SR20DET,

 

it was equipped with a complete exhaust system without catalyst, fuel pump walbro, flywheel 6kg, intake filter Apexi, intercooler Silvia S15, delete EGR, spark plug irridium IK24, Boost controler Greddy profect b2 with 15PSI of boost, injectors OEM 370cc, a Eprom Horsham.dev to configure the set

 

With 15PSI, my injectors OEM 370cc had a duty cycle between 90 and 95%

 

This point reminds me that I used to have Datascan on live readout when I had a car pc and it would usually peak at 96% duty cycle at 9psi.