just a thought, im sure ill be shot down but here goes

 

its widly thought that you should not exceed 80% duty cycle on an injector

 

most people will not go over 15psi boost due to the injectors reaching 80% duty cycle- correct? limiting you to around 380bhp

 

however it has been my previous experience that side feed injectors as fitted to the 300, and for that matter the 200sx are quite happy running up to around 95%- perhapse because they are better cooled.

 

has anyone ever tried running higher than 80% and for that matter has anyone ever had a failure due to this?

 

theoretically you could reach 450 bhp?

 

what cc are gtr injectors?

 

it would be interesting to hear some thoughts.

 

ps im not sure id want to try it on my engine but might have a go at 17psi with some research.

 

let the fireballs rip

the main problem with running high duty cycles is you loose the safety margin - e.g. you're running around at 95% then go for a drive on a nice cool morning thinking "what's that rattling sound?"!

very true, perhape my point is that is 80% a bit too safe when you could get a fair bit more and perhaps utilise the maximum efficient range of the std turbos- 18psi

 

however im not suggesting we all go out and turn the boost up untill we get dett etc. i totaly understand why all tuners would want too keep a nice margin.

 

nissan themselves gave a very good margin as stock

 

perhapse its just me being tight but it seems amazing that people would spend well over 1k on new injectors and rails. you can pick up a set of huge cossy injectors for under 100.

 

i think i saw a thread about 350z injectors recently. perhapse there is a good market for an affordable top feed rail.

very true, perhape my point is that is 80% a bit too safe when you could get a fair bit more and perhaps utilise the maximum efficient range of the std turbos- 18psi

 

perhapse its just me being tight but it seems amazing that people would spend well over 1k on new injectors and rails. you can pick up a set of huge cossy injectors for under 100.

 

i think i saw a thread about 350z injectors recently. perhapse there is a good market for an affordable top feed rail.

 

THANK GOD SOMEBODY ELSE SEE'S WHAT I SEE!!!!!!!!!!As stated by Rich the stock injectors are at there absolute MAX at 14.5-15psi so you cannot utilise all the power of the Tubs without going Major Lean and blowing everything up (1st hand knowledge here :()

 

So to get to the higher amount of boost then Injectors need to be upgraded with a higher CC and the next size up for 300zx's are 555cc which are too big for what people with a slightly upgraded setup and will be pointless (including the whopping price)

 

I agree with you totally on its stupid how Cossie injectors are 1/10th the price but the same size but im unsure about fitment which is why i suggested the 350z ones as they can be bought as 440cc and have similar fuel pressure to a 300zx and according to one forum member a specific series have the same o ring which would entail that fitment may not be a major ball ache and at half the cost much much better value :)

 

If you have a lookie at my 350z injector thread it had no interest really which is a shame as there's not too many people on this forum willing to explore alternatives and too many are 'happy to get the check book out' so to speak :tongue:

 

Your train of though on upping power was my exact same thought and im glad to see we both saw that it was the Injectors limiting the power and that upgrading them was the best option but not to spend a fortune on Oversized and Overpriced injectors

very interesting tread

 

welldone to both you guys for exploring the injector situation on the 300zx.

 

Im in the middle of a engine build at the moment and i for one will be looking into what has been said by Munny975.

I think I have mentioned before - I have had the same thoughts - and I am going with top feed RC Engineering injectors fed via a custom top rail. All injectors from [RCE] 555-1200cc are the same price - about £60.00 each and of course the top feed injector types are many and plentiful should I wish to change - most manufacturers use them these days. It won't be ready until end of November now though ;-( Lower plenum has been machined with new bungs for the top feeds though - complete with silicone o-rings - no metal to metal contact - the whole rail will be insulated from conducted engine heat ;-)) I will get some pics up when I have something..

 

Best regards to all. Andy

ill post up some pics of my diy fuel rail fitted on the kit car

Yes please - that might help ;-))