Recently Purchased DPCHIP, 3Inch Exhuast - Findings. 1kz

[ARK48 Lurker Find all posts View Profile Close ARK48]

Recently purchased an exhuast/chip package for my 2004 120 (1kz) from Berrima Diesel,

3inch allumised steel full exhuast (included) dump, mandrel bent (no brand) + DP CHIP.

Although the power gains with both seem to be more than noticeable, I have noticed some odd behaviors and want to know peoples feedback.

Firstly I just added the exhuast, these are my findings.

Freely REVs now and accelerates through to band much better than stock system

However, I feel like I've lost holding power and bottom end tourque, it's hard to explain but I really have to ride the clutch to build up enough pressure to get the the car moving on a hillstart/cold engine, also going up hills i have to drop back gears because i loose REV's/momentum

its like blowing air through a big straw, I did lots of research over different systems (Beaudesert recommended 2 3/4, berrima recommended 3inch)

I read many posts with conflicting statements surrounding back pressure of 3inch exhuast, however i tend to believe that backpressure should almost always be handled by the turbo and the size of an exhuast on a turbo car shouldn't really affect anything other than allowing gases to escape faster.

As said the car is is REVing better on flat road when i put my foot down, however seems to struggle more than it used too with stock exhuast under load, the only thing I can think that's causing this is back pressure, but why.....

Secondly I've added the DP Chip,

Noticed an increase in power through the MID/TOP end, running it on setting 9 (max) i've almost fixed bottom end power but still struggles a little to hold when under load, almost considering purchasing the beaudesert (2 and 3/4 system) to confirm my suspicions,

I want my low end torque back

[ejukated Senior Member Find all posts View Profile Close ejukated]

Generally speaking, you can certainly go too big as you need exhaust gas velocity to efficiently evacuate the exhaust from the rear of the turbo. If its too big you can get vortecies forming so whilst you have reduced backpressure the flow is not smooth.

I've never driven a 1KZ with 3" but I find it hard to believe a motor that revs to 4000rpm and makes ~100kw needs an exhaust that big!

[ejukated Senior Member Find all posts View Profile Close ejukated]

you could try experimenting with just a larger dump and stock exhaust for a back to back, that would only cost time if you can fit it yourself.

[ARK48 Lurker Find all posts View Profile Close ARK48]

Appreciate the response ejukated, I will be continuing to investigate this as I want to ensure I'm getting the most out of my new additions.

Unfortunately I no longer have the stock mid/tail pipe, I'm almost sure it would not join up to the 3inch dump without modification aswell.

Looking forward to hearing other members thoughts..

[ScoticusMaximus Member Find all posts View Profile Close ScoticusMaximus]

i have written in threads many times about having a 3" and ditching it for a 2.75", best thing i did, so much better down low than the 3". i also have the steinbauer, safari snorkel and have a boost controller with a little more boost and i still dont see high exhaust temps, even when towing up hill.
cheers,
Scott.

[ejukated Senior Member Find all posts View Profile Close ejukated]

Appreciate the response ejukated, I will be continuing to investigate this as I want to ensure I'm getting the most out of my new additions.

Unfortunately I no longer have the stock mid/tail pipe, I'm almost sure it would not join up to the 3inch dump without modification aswell.

Looking forward to hearing other members thoughts..

On a separate topic.. how may km are on your car? I recently discovered my 2nd gear synco is on the way out

[ARK48 Lurker Find all posts View Profile Close ARK48]

On a separate topic.. how may km are on your car? I recently discovered my 2nd gear synco is on the way out

100,000 kms, shes only a baby

[Razorback81 Advanced Member Find all posts View Profile Close Razorback81]

would adding a smaller tail pipe make the restriction required ? 3" to 2.75"
letting out the turbo quicker into the bigger exhaust, then restricting the out flow ( like putting your finger on the end of the hose )

i am sort of in the same position but with the KD engine

the 3" exhaust fells good but didn't make as big an improvement as i was hoping
only issue is the slight drone at the rpm i drive at

on my race car
when i had the factory computer on my WRX engine in the race car with a 3" exhaust (3ft long) the engine would see boost spikes & would over boost when pushed hard
i mad a reverse cone and welded it in the tail pipe and reduced it from 3" to 2.5" and had no more issues
( lost a small amount of power but 2kw's wasn't enough to worry about)

just thinking out loud

[ejukated Senior Member Find all posts View Profile Close ejukated]

would adding a smaller tail pipe make the restriction required ? 3" to 2.75"
letting out the turbo quicker into the bigger exhaust, then restricting the out flow ( like putting your finger on the end of the hose )

i am sort of in the same position but with the KD engine

the 3" exhaust fells good but didn't make as big an improvement as i was hoping
only issue is the slight drone at the rpm i drive at

Not quite, that just leaves a large empty chamber which takes longer to fill up. The most ideal would most likely be a 3" dump that tapers into a free flowing 2.5" system or 2.75"

on my race car
when i had the factory computer on my WRX engine in the race car with a 3" exhaust (3ft long) the engine would see boost spikes & would over boost when pushed hard
i mad a reverse cone and welded it in the tail pipe and reduced it from 3" to 2.5" and had no more issues
( lost a small amount of power but 2kw's wasn't enough to worry about)

just thinking out loud

Depending on the year, the WRX turbo is computer controlled with a PID closed loop controller. When you free up the exhaust, the turbo is more responsive and the closed loop boost controller is now too slow, so it overshoots. They can be recalibrated to you don't have overshoot or oscillations.

[bprado Junior Member Find all posts View Profile Close bprado]

Have you tried to clean out yoir throttle bodie iv done similar mods on mu 04 but its auto and it goes good now. But iv got a rear muffler fitted on mine to krep the nose down

[t303 Senior Member Find all posts View Profile Close t303]

I have had a snorkel, boost controller and DTRONIC chip on my KZJ95 since I got it 8yrs ago. I have always had a problem with the EGT alarm going off when it felt like the engine had a lot more to give. Finally replaced the stock muffler with a sports muffler (left rest of system standard) and it has made a HUGE difference. Now when pulling up a hill the EGT takes a lot longer to climb and you can feel the turbo is on full song for ages before the alarm sounds. I can't detect any change in the torque/power curves, it just keeps pulling for what seems, relative to the old setup, forever. Towing the 2T van I have noticed the increase in power, and the EGT/coolant temps are both lower. It is obviously moving more air through the engine and exhaust. There is more drone, and if you leave the window open you can hear the roar as the turbo starts working, but with the road noise from big AT tyres and fairly stiff suspension the exhaust noise is not intrusive.

[floatingkiwi Lurker Find all posts View Profile Close floatingkiwi]

And your dump pipe is still factory?

[t303 Senior Member Find all posts View Profile Close t303]

Yep, simply replaced the muffler.