Interesting Problem....

[joeyjoejoejuniorshabadoo]

i'm off to get my 2835 installed in a couple of weeks so i decided to do a few of the less time consuming supporting mods myself... (fuel pump etc)

so i installed some new splitfire coils and some bcpr7es gapped to 0.8... and put the car back together

when i took it for a drive i noticed 2 things...

1) it feels smoother and more linear throughout the rev range

2) its running less boost. ?!

formerly i was getting .9 bar with boost controller (bleeder) switched off but spiking out to 1.1

now its getting .5 bar and not spiking past .55

so i turned up the bleed valve to .8 bar and it holds nicely without spiking past .85ish

car has pfc, fmic, turbo back etc. how much boost shold it be producing with these mods?

also when the car was tuned a year ago @ racingline, nige said there was a tiny leek that he didn't have time to locate,(i needed transport back) but the car was running fine and not to worry. the car ran strong for a year with no problems.

so... my question is this...

was the car running with a leek that was acting like a bleed valve and upping the boost for a year

OR

did i not put a hose on properly this time? (i have checked and checked again...)

[Guilt-Toy]

rice costs 20c a kg in china.

[madbung]

Not an answer to your question but i'm curious re: something else, if you're running pfc & splitfires why are you gapping down to .8 on your plugs?

Edited June 5, 2008 by madbung

[paulr33]

it sounds like you were running unlimited boost before which tapers off around 1.1bar on the stock gtst setup

[joeyjoejoejuniorshabadoo]

So one of the hoses around the coil pack cover area could have caused this?

[joeyjoejoejuniorshabadoo]

Oh and they're gapped to .8 cause i've been told by many many people that would be the optimum gap...

[madbung]

Oh and they're gapped to .8 cause i've been told by many many people that would be the optimum gap...

On a stock ecu/tuned car running 98ron yes

With an aftermarket ecu, tuned and new splitfires your gap should be 1.1..

The idea of setting the gap to .8 is a cheap get around for the pinging/breakdown issues most skylines have on 98ron when using the factory tune.

It's a stop gap, for peeps that can't do it the right way atm...with your parts you shouldn't be bothering with that crap.

Embrace the strength of a bigger spark!!

I did the same thing when I first got my nissan, until I got around to doing it right.

[joeyjoejoejuniorshabadoo]

i dunno... taking all that shit off again... might give it a go when i get round to installing those injectors that are still sitting in the box next to my bed

any ideas on the prob guys?

[GeeTR]

it may be late but sorry, but are you saying you wacked some new plugs and splitfires in, and now it holds boost properly; without spikes? strange. Did you replace any lines, anything at all to do with boost control?

[joeyjoejoejuniorshabadoo]

All the lines attached to the elbow came off and were put back on. But nothing else

[ztuned]

was the splitfire coilpacks worth it? im putting GTRS, pfc, injectors and z32 afm into my car in a few weeks.

just wondering if it's worth the money getting the splitfire's before i get a tune

[joeyjoejoejuniorshabadoo]

i'd say... even if your coils are ok now they'll be on the way out

[rev210]

Coat the old coils in silastic and you can keep them going for a very long time. looks ugly but, no one looks at them anyway.

Sounds like one of the hoses was not on right.

[joeyjoejoejuniorshabadoo]

yeah that is what i'm thinkin

coils aren't really cosmetic anyhow

[MBS206]

Even once the coilpacks are "coated in silicon" the car will fart and miss above 5000RPM if you gap is at 1.1mm WHERE IT IS MEANT TO BE!

Once you chuck the Splitfires in, (Or even BRAND NEW stock coilpacks) you will be able to gap plugs to 1.1mm AND rev to redline perfectly cleanly, producing a better flame front in your engine.

Technically, from what I can gather, it will also allow you to run slightly more advanced timing when you do the tune, as you have a wider initial flame front.

Hence @ 1.1mm you should be able to make more power cleanly...

[rev210]

Even once the coilpacks are "coated in silicon" the car will fart and miss above 5000RPM if you gap is at 1.1mm WHERE IT IS MEANT TO BE!

Once you chuck the Splitfires in, (Or even BRAND NEW stock coilpacks) you will be able to gap plugs to 1.1mm AND rev to redline perfectly cleanly, producing a better flame front in your engine.

Technically, from what I can gather, it will also allow you to run slightly more advanced timing when you do the tune, as you have a wider initial flame front.

Hence @ 1.1mm you should be able to make more power cleanly...

Depends on a variety of things but, in this case the 0.8mm gap is going to be better at high rpm/boost and power levels in terms of reliable spark.

1.1mm is a nice gap for a cleaner burn at lower rpm, hence it's factory.

The factory coils are just as good as splitfires by the way. Splitfires are just cheaper to buy new.

[paulr33]

yeah adding splitfires gives no power gain

theyre only needed when your get misfire city on boost

this is when the stock coils die

[madbung]

Depends on a variety of things but, in this case the 0.8mm gap is going to be better at high rpm/boost and power levels in terms of reliable spark.

1.1mm is a nice gap for a cleaner burn at lower rpm, hence it's factory.

The factory coils are just as good as splitfires by the way. Splitfires are just cheaper to buy new.

How do you figure a smaller spark is better on higher boost?

Gapping down is a very basic and simplistic way of advancing timing...used to get around pinging on a stock non-tunable ecu.

If you tune the car correctly with 1.1 gap it is better...you can actually feel the difference in top end, revs more freely.

Splitfires don't create more horsepower, but they do give a stronger spark (%20?) which certainly helps.

But hey if 8 is your lucky number.... who am I to say different.

[rev210]

How do you figure a smaller spark is better on higher boost?

Gapping down is a very basic and simplistic way of advancing timing...used to get around pinging on a stock non-tunable ecu.

If you tune the car correctly with 1.1 gap it is better...you can actually feel the difference in top end, revs more freely.

Splitfires don't create more horsepower, but they do give a stronger spark (%20?) which certainly helps.

But hey if 8 is your lucky number.... who am I to say different.

I'm sorry but, 'feeling the difference' in top end?

Unless the tune was rooted before I can assure you that not only is there no power difference but, also this 'feeling' is peculiar only to cars that started out with a spark issue or were seriously 'under-gapped' for the density of the air/fuel mixture.

Smashing more power/rpm/boost into a motor and gapping down on the exsisting heat range is tuning 101( for all cars). If you get no joy in the top end after gapping down on the exsisting heat range you go to a colder plug etc.

For example, for most of the NA V8's I've tuned you can just about go off a rule of thumb that is gap down 4 thou for every 50hp added.

I've been doing this to alot of different cars over the years so 'luck' has nothing to do with it.

There are some serious horsepower GTST's & GTR's running around with factory coils as well. Splitfires do one thing well and thats make a cheap replacement for the expensive factory coils when they are shagged.

Edited June 8, 2008 by rev210

[joeyjoejoejuniorshabadoo]

Spose i'll ask rob what he recommends when he tunes it