1/4 Mile Question:

[adis]

1/4 mile question: Few months ago i went to Heathcote for the first time and ran my car 1/4 mile. I did worse than i expected.

Ever since that day me and a mate have been debating our actions that day, and we haven't resolved it therefore i thought i'd ask you guys for your opinions

Car: R33-hiflow turbo, Mines ecu, 16 psi, 2.5 inch turbo back exhaust, split fire coil pack, apexi 3 inch intake, r34 cooler.

The big QUESTION: When i got to Heathcote, my friend advised me to unbolt my exhaust just before cat as "this will improve" the car, car will go better in his opinion.

I ran 14s flat at best, embarrassing, and in my opinion the car didn't run as good, just sounded loud and tough, but i don't think it went any better, if anything, went worse.

So, questions is, DOES UNBOLTING EXHAUST BEFORE CAT HELP? Please elaborate on your answers-some people say no, you need compression others say yes, better flow. ?

Edited May 11, 2010 by adis

[R31Nismoid]

Unbolting the exhaust won't do sh|t if the exhaust is already free-flowing enough. So unless you've tested it on a dyno to actually be a restriction then i'd be inclinded at this stage to say there is no benefit. (See point #4 further down).

So that part of your thread is largely pointless, so don't listen to your friend anymore me thinks...

What information/issues there are though... as follows.

1. What were your 60ft times?

2. MPH?

3. Actualy ET?

The above three will give a much better idea of what is going on.

4. You are running a yum-cha ECU/Tune (ie, not a properly tuned setup). It's probably rich as all buggery which is not helping the situation so dropping the exhaust wouldn't have even made much difference if there was restrictions anyway.

[adis]

Unbolting the exhaust won't do sh|t if the exhaust is already free-flowing enough. So unless you've tested it on a dyno to actually be a restriction then i'd be inclinded at this stage to say there is no benefit. (See point #4 further down).

So that part of your thread is largely pointless, so don't listen to your friend anymore me thinks...

What information/issues there are though... as follows.

1. What were your 60ft times?

2. MPH?

3. Actualy ET?

The above three will give a much better idea of what is going on.

4. You are running a yum-cha ECU/Tune (ie, not a properly tuned setup). It's probably rich as all buggery which is not helping the situation so dropping the exhaust wouldn't have even made much difference if there was restrictions anyway.

Correction, when i ran the car i had 14 psi, and stock cooler and stock 2.5 inch intake with pod. (190kw at wheels)

1. What were your 60ft times? 2.37

2. MPH? 104.02

3. Actualy ET? 14.0034

temp 35.3 C (lol)

-is it possible for the car to be more laggier? Because for some reason the car felt laggy once i took the exhaust off?

[R.3.2.G.T.R]

back pressure loss??

[R31Nismoid]

Correction, when i ran the car i had 14 psi, and stock cooler and stock 2.5 inch intake with pod. (190kw at wheels)

1. What were your 60ft times? 2.37

2. MPH? 104.02

3. Actualy ET? 14.0034

temp 35.3 C (lol)

-is it possible for the car to be more laggier? Because for some reason the car felt laggy once i took the exhaust off?

Ok so…

1x stock turbo

1x 2.37 60ft

1x 14.0 ET

1x approx 45 degree track temp/35 ambient

Sounds 100% normal to me all things considered.

Exactly what I would expect from a 60ft such as that on factory turbo without a proper tune and decent 60ft time.

The fact you are running 14psi through it wouldn’t have been doing any favours either.

Then add in the factory I/C… high ambient temps… after a few runs it would just be pushing hot air around. It's big fat mess of a situation! If anything running a 14.0 was probably as good as it was ever going to get!

Either way as I said – Sounds 100% normal. Nothing to worry about. Dropping the exhaust just added to the already bad state of tune/setup so no surprise it probably did more harm than good.

[Johnny]

Id say the ecu aint the best bet. Also what tyres u running? drop some psi before the run?

[PM-R33]

Yep times seem perfectly normal as Ash has said. Also what suspension is in the car and what sort of tyres were used?

[paulr33]

check the tune - how well is it tuned? is it tuned enough?

check your tyres (good? worn? new? wide enough?)

check tyre pressure (what was it?) should be 20psi for drag

with the same mods, but stock turbo i was able to do 13.7 @ 105mph with cold track and slipping diff

so it should have been quicker. my 60s were lower and my mph was the same and 1/4 was less

[FineLine]

check the tune - how well is it tuned? is it tuned enough?

check your tyres (good? worn? new? wide enough?)

check tyre pressure (what was it?) should be 20psi for drag

with the same mods, but stock turbo i was able to do 13.7 @ 105mph with cold track and slipping diff

so it should have been quicker. my 60s were lower and my mph was the same and 1/4 was less

What paul said. I was able to run 13.4 with that mph.

Concentrate on your 60 ft times and your et.s will drop considerably.

[jjskyline79]

I ran a 14.27 stock straight off the boat

thats was later found out to be 255bhp at .5 bar boost

Edited May 11, 2010 by jjskyline79

[West]

You have a Hi-flow turbo, Split-fire coil pack, Mine's ecu........etc and you're running R34gt-t cooler?

[STATUS]

for starters you need a tune to suit the hiflow the mines ecu is nowhere near optimal and secondly the r34 coolers are junk. Fit a decent cooler and get a tune.

[STATUS]

here is a mines map versus factory... bugger all diff. It is doing jack for you... time for a decent ecu and cooler as posted previous.

[adis]

here is a mines map versus factory... bugger all diff. It is doing jack for you... time for a decent ecu and cooler as posted previous.

I made 220kw on mines ecu, 16 psi, and all those mods. If i was to get a front mount, and get ecu, you still cant go past 230kw due to injectors and z32 maxing, so is it really worth it? ... i thought about it but in the end opted not to waste 1k for 10kw. My current tune is still safe, on 220kw

When i ran the car i only had 190kw and didnt have half the mods. Will be interesting to see what i get now, with exhaust on.

[paulr33]

average power makes the car quicker = quicker 1/4 time

peak power in one spot means nothing

on the street you car would be ass to drive, it would lack power and midrange

with a full tune, intercooler and real ECU the car would fly

[STATUS]

I made 220kw on mines ecu, 16 psi, and all those mods. If i was to get a front mount, and get ecu, you still cant go past 230kw due to injectors and z32 maxing, so is it really worth it? ... i thought about it but in the end opted not to waste 1k for 10kw. My current tune is still safe, on 220kw

When i ran the car i only had 190kw and didnt have half the mods. Will be interesting to see what i get now, with exhaust on.

your on crack if you make that much power (cant be nice power either) on a r34 SMIC... its a time bomb. I hope you monitor your ait's.

[3LGODZILA]

also wouldn't call 16psi out of a highflow turbo running though a r34 SMIC a 'safe tune'

[R31Nismoid]

I made 220kw on mines ecu, 16 psi, and all those mods. If i was to get a front mount, and get ecu, you still cant go past 230kw due to injectors and z32 maxing, so is it really worth it? ... i thought about it but in the end opted not to waste 1k for 10kw. My current tune is still safe, on 220kw

When i ran the car i only had 190kw and didnt have half the mods. Will be interesting to see what i get now, with exhaust on.

10kw peak?

Or how about 20-30kw through the midrange? That is certainly worth the money of a FMIC ($500) and ECU/Tune ($1800). You don't need to get injectors or AFM... and hell if you get a PFC etc you can tune past the AFM quite safely anyway within reason.

That is where the real gains of a proper ECU & tune lie, and that is what will make a car fast.

The Mines tunes generally are only marginally better than factory in most cases - they are super fuel'd and hurt the midrange power signifigantly as a result.

Yes they are "safe", but an aftermarket tune can net

1. Better economy

2. Better mid range/transitional power

3. Better peak power

#2 obviously being the biggest improvement and you'll easily notice this driving it after a decent tune is performed.

also wouldn't call 16psi out of a highflow turbo running though a r34 SMIC a 'safe tune'

Probably the only saving grace is the Mines ECU doing its super-fuel up

Either way i agree, running that much boost is asking for trouble.

After a good 15mins hard drive on the street with sufficient heat soak and so on it's probably just luck nothing is really going wrong.

[boostn0199]

Cmon man you wanna have your car running decent times and you dont want to get a decent ecu and tune a front mount, thats one of the first things youd want to get let alone looking at your suspension and tyre issues after if you want to improve your times even more.

[adis]

your on crack if you make that much power (cant be nice power either) on a r34 SMIC... its a time bomb. I hope you monitor your ait's.

Im on crack? ill ignore that just be careful my friend...im not here to insulted, just asked for opinion.

I took it to a tuner like your self, he chucked it on a dyno and thats the result i got.