hi guys, been playing with my zed on rolling road today and was woundering what psi i can safely run at with stock internals and head gasket????

 

we set up at 16psi and through out rev range she was still running abit rich!!

chip was made for smithy's zed with upgraded pistons and rods!

 

this is my set-up! :nana2:

 

blitz sus induction

G reedy side mount i/c's

apexi avcr boost controller

nismo 555 injectors

smithy's t28 hybrid turbo's

ported and flowed exhaust manilolds

split divorse down pipes

custom de-cat pipes

scorpion silencers

 

i dont want to strip and rebuild engine again is water injection a good way to go!

to be safe and for long life boosting id say 14 psi. 16psi isnt too bad but you may be pushing it a tad. looking at the with the rest of your mods though its crying for some uprated internals to unleash some power ;)

sort of wish i chucked some more bits in when i had engine out!! but funds wouldnt stretch any more! its been of the road for a year so i want to keep it on the road at least for the summer!

when dyno run at 16psi there was defo no detonation and i had plenty of fueling! even that into account would a piston still let go purely because of too much pressure?????

 

to be honest i never accelerate at max boost for long (i.e flat out )

 

on rolling road i couldnt get a read out as combination of loads of torque and positive camber ment i had wheel spin throught out rev range so haveing a job making boost!!

sort of wish i chucked some more bits in when i had engine out!! but funds wouldnt stretch any more! its been of the road for a year so i want to keep it on the road at least for the summer!

when dyno run at 16psi there was defo no detonation and i had plenty of fueling! even that into account would a piston still let go purely because of too much pressure?????

 

to be honest i never accelerate at max boost for long (i.e flat out )

 

on rolling road i couldnt get a read out as combination of loads of torque and positive camber ment i had wheel spin throught out rev range so haveing a job making boost!!

With 555 nismo's 16 psi is no problem! you can probably go a little higher as you have not got stock injectors but the Standard tubs are not so efficient above 17-18psi.

Stock 370's are maxed out at over 15 to 16 psi so you are very safe with your Nismos

Stock internals are roughly estimated at there limit at 600fwhp.Nissan Head Gaskets are Very good.

so as ive got t28 hybrids and nismo 555 injectors ive still room to play???

im no where near 600fwhp!

trouble is even with good fueling there must be a point where combustion chamber cant take any more???

i carried out power run at 18psi and afr was still good through out rev range but was worried i was getting carried away??

 

thanks for the help so far!! regards steve

sort of wish i chucked some more bits in when i had engine out!! but funds wouldnt stretch any more! its been of the road for a year so i want to keep it on the road at least for the summer!

when dyno run at 16psi there was defo no detonation and i had plenty of fueling! even that into account would a piston still let go purely because of too much pressure?????

 

to be honest i never accelerate at max boost for long (i.e flat out )

 

on rolling road i couldnt get a read out as combination of loads of torque and positive camber ment i had wheel spin throught out rev range so haveing a job making boost!!

an extra 2 psi may not sound alot but once the piston has compressed the increased mass of air, the combustion pressure would be alot more. maybe 16psi would be ok, just be sensible id say. im sure you wont have any fueling problems with the 555's but if you did get any detonation from the increased pressure it could go pop!

 

water injection would be a good way to go to try and prevent detonation as would ensuring you have the correct plugs. also check that your det sensor is working properly and that it hasnt been bypassed. :)

Stock internals are roughly estimated at there limit at 600fwhp.Nissan Head Gaskets are Very good.

 

i stand corrected! didnt realise the internals were that 'bullet proof'

Most people try and push 16 - 17 psi out of stock injectors!? You are one better with the nismo's! They are supposed to be ample untill roughly 500rwhp.

The next thing to upgrade would be the Turbos then so-on.

i stand corrected! didnt realise the internals were that 'bullet proof'

Jun 300zx suppossedly (forgive my spelling Lol) managed 1000fwhp on stock pistons and rods/crank so i have been told! and its listed on the spec on there website. :confused: :cool:

There are lots of topics regarding stock internals if you use the search button Lol :D

best speak to some1 like Bazza, Mac or cj etc as they will prolly have some sound advice on the matter :)

i fitted new det sensor and loom when engine was out and am running ZFR7F-11 plugs as john dixon is!!

just thinking of a safe way to get more power without having to pull engine for the 3rd time!

if i run water injection, have no det and good fueling how far could i go???

may be i/c spray coolers are a way to go?? that way i can get more bhp from the pressure i already am running???

I am sure Smithys T28 hybrid turbos will go quite along way! Have you spoken to him?

1000fwhp on stock internals????

how long would that last????????????????????

Seeing as you've bigger tubs, bigger injectors and taken care of the intake chrage temps with better SMIC's, then 16 psi is okay IMO.

However the main part not forged in our block is the pistons and once you start upping the PSI and seeking more fuel, there was a flaw in the pre 95 Zeds with the fuel rails not providing enough fuel to No.6, hence why this one normally goes bang 1st. Under normal conditions it's not a problem.

So in short expect a minor rebuild down the line ;)

Oh and check timing is spot on if running too rich, though mine is constantly a little rich to further aid detonation.

If wheels are spinning on the rollers too much, try a rolling road set up like Thor's where they take the wheels off and bolt the hubs up.

Will reply to yer PM shortly.

cheers

smithy

1000fwhp on stock internals????

how long would that last????????????????????

As long as it took you to type the Above probably :rofl:

well going by the speed i type that car must of lasted longer than i thought it might!!!!

so would fitting uprated fuel rail help??

water injection??

in the long run im just trying to avoid removing engine and aviod rebuild in the future!!!

but i cant have everything!!

I'm confident you could run 16/17psi all day long with that setup, especially seeing as you are running rich there should be no problems with detonation...

IMHO water injection is all good. See http://www.nissanperformancemag.com/january04/300zx/

 

If water injection allows 14psi on poor American gas it has to be good....

well going by the speed i type that car must of lasted longer than i thought it might!!!!

Jun300zx

i made my own water injection for a 1/4 mile sprint car i used to have. it was a little fiat uno turbo which on the plenum had an overboost switch, when the boost pressure reached 0.7bar it would activate this switch giving a signal for the ecu to retard the ignition. this switch was removed as i was boosting more that 0.7 bar but i ended up using it to power the water injection... i drilled and tapped into the inlet manifold to house 2 injectors, i then connected the overboost switch to the rear washer bottle and plumbed it all together, so at 0.7 bar it would inject water.!...

 

it didnt work, my gash diy job just basically stalled the car lol! it needed the pressure regulating and i couldnt be assed to mess around with that as i was only pushing 170hp and it wasnt worth it anyway :)

 

prolly a good idea for the zed for extra peace of mind and the aquamist kit isnt too expensive iirc

hi guys ive been off and chated to my rolling road guy (who builds rally cars) and read almost every blown engine thread on this site and have come up with a theory and wanted to no youre ideas please????

 

most engines blow because of no 6 cylinder being the last on fuel rail and running leaner than the rest! correct?

 

people fit forged pistons to cope with this extra temperature?

which in my theory only masks the problem!

 

if i fit upgraded fuel rail to eliminate problem and water/methonal injection to reduce all cylinder temperatures this will give me a realiable high power engine (500bhp) with out having to pull my engine again this year???

the good thing about water injection is that it creates power which would allow me to run slightly less boost for same power gain???

 

what are youre thoughts please???????????????????????????????????

As far as I know water injection robs power, albeit only a small amount. This, however is offset by the ability to run higher boost adn/or safer boost. I guess adding methanol or something can put some power back and/or protect the engine even further.

 

Def a good idea though, I am going to run it on mine and I am only hopeing for 400bhp, and some would argue that I dont need it, but its safer, and it cleans the engine too. A win win situation.

the mother of mods for £ per bang would be "avgas" yes the stuff they run cessna,s with, think its about 110 octane :D could turn the heat up with that stuff ile tell ya

unfortunately it's not just the rail layout, cylinders 5 and 6 get the most air due to the plenum design and coolant flow in the block is most restricted back there.. I don't know which is the biggest contributor but you should still be able to manage a reliable 500 hp in any case.