How come lost power after upgrade from stock exhaust?

[jamslau]

Hi ppl, anyone has improved power, reduced lag by upgrading coupe's stock exhaust? I want some growling sounds too
Does the ECU need programming?
I replaced stock exhaust with one straight through muffler,
the car lost 2 secs (0-60mph) used to be 8sec (was trying to achieve close to the specified 6.5sec) .... now 10 sec ,
fuel consumption increased 20%!! Used to be 400km/tank, now 320km/tank
Something is wrong here... Anyone has achieved exhaust pipe nirvana? Can share your secret? TqTq

[DeaDLocK]

Which sections of the exhaust did you change?

[jamslau]

Removed cat & 2 mufflers before & after rear wheel
http://www.facebook.com/photo.php?fbid= ... =1&theater

Replaced with single 3" straight muffler, to dual 2" exit on driver side.
http://www.facebook.com/photo.php?fbid= ... =1&theater

[DeaDLocK]

It's a bit odd. Not sure what the issue is, but make sure the lambda sensor wasn't worked loose (don't know how this could have happened, but you never know!).

It could also be something unrelated and pure coincidence that it happened at the same time. How are running temperatures? Do you have the kit to read the engine codes?

[jamslau]

Where is a good workshop to sort turbo issues? Just stock power will do, don't want 10-20k upgrades.

[ognam]

1) maybe your fuel consumption is worse because now that your exhaust sounds good, you tekan a lot.

2) why the dual exit? Why not straight all the way?

3) what turbo issues?

[saabretooth]

I suspect that due to too much air escaping, the car loses the low end pul. the velocity of air has slowed down due to larger exhaust.

too much air in/out, means the ECU could be dumping fuel to richen the mixture and bring it back to its standard setting. thus, increasing fuel consumption.

you might need a tune to normalize it. even then you'll lose your low end pick up, unless you have system to ignite fuel after the downpipe and speed up the exhaust air going out.

either that, or a damaged lambda sensor :p

[pistole]

stock is best

.

[bravosx]

Your dual tail pipe a side exit? Looks like your pipe is shorter in length. No?

[jamslau]

Stock is too quiet for my liking, i'd like a sporty exhaust note.
Twin 2" is due to lack of height for 3", currently it's already scraping the largest speed bumps
2x2"=4"?
Yes it's shorter.. But I thought turbos don't need back pressure, shorter is better,No?
Many different opinions on this, from the research I've read...
Stock: turbo kicks in after 3500rpm with stronger torque, (no pop sound)
Current setup: turbo starts around 3000rpm, no "kick" but gradually starts pulling till 6500 rpm, exhaust pop sound when shift at high rpm (5000)
Looks nice, Sounds nice (slightly too loud , but power gone

[jamslau]

Possible solutions:
1. Tuning ecu, check lambda sensor, check boost pressure
2. Improve velocity by using smaller pipe 2.5"?
3. Straighten to rear exit (which still has two 45 degree turns)
4. Revert to stock exhaust

[raitag]

When u remove the cat, better and silencers, u get better flow, resulting in higher HP... BUT u will lose some torque... dyno the car and see the result...

Exhaust tuning is a black art... u do it wrongly, u will lose power and torque...

i removed the triangle silencer and i lost torque... and since i use the car mainly in town, i replaced it with CSC unit... power back but damn quiet la...

[fabianyee]

exhaust tuning is both art and science... Proper tuning involves calculations on length, pipe cross section area and total volume...

BTW, 2x2" pipe has less cross section than a 1 x 3" pipe... How so? cross section area = pi x radius x radius
so
3" : 2 x 2"
(1.5 x 1.5) x pi : 2 x (1 x 1) x pi
2.25 : 2
1.125 : 1

So a 3" pipe has slightly more cross section area compared to 2x2" pipe. Ratio of 1.125:1

[saabretooth]

Is not back pressure. It's the lack of velocity of the air. When the air slows down you lose the torque pull feeling. And thus the ability to pull off as fast as you used to. If you want to have 2x 2" mufflers, make the mid pipe a bit smaller. That saying, you haven't solved the ecu problem of the AFR.

[DeaDLocK]

I think all this talk of air flow area of 3" vs 2x2" etc is completely irrelevant if his downpipe is stock, which I am assuming it is.

[raitag]

stock down pipe is good for stock turbo...

[jamslau]

Down pipe is stock. Wow! Thanks for the calculations I forgot all my maths already
Must go tell the exhaust guy

I think could be loosing boost pressure somewhere, cos I just sent to workshop to fix oil leaks, they removed turbo, exhaust manifold, intake piping etc. they replaced hose clips, looks ok but I need a boost meter to know... Btw What is the stock pressure supposed to be at 3000,5000,6000 rpm?

[DeaDLocK]

Stock boost pressure is sustained 1 bar (ignoring overboost and ECU boost acceleration retardation). You should see this at 3000+ and it will start going down by around 5000+. If you have a boost leak, a boost gauge will show it very clearly. Another simple thing you can do is plug in a laptop to read the codes (but you need the right cables).

[jamslau]

I dyno the coupe & it showed 1.4 bar at 4000 rpm, then going down to 1bar at 5000 rpm & 0.8bar at 6000 rpm
Is that normal?
http://www.facebook.com/photo.php?fbid= ... =3&theater

[jamslau]

Ok, 1.4bar is not normal, so if the ECU is not limiting it, that means the solenoid valve is faulty? Where is this located?

[ognam]

Yes. Your EBV could be dirty and jammed hence the spiking. Give it a good clean using carb cleaner or WD40. It's located near your battery tray. Looks like a bell.

You're running a bit rich now because of the boost spike. Other than that, power seems healthy for a stock (?) coupe. Give/take 225bhp. But you have lost a bit of torque.

[myLittleMonster]

I think your measurement and set up for the coupe is quite wrong if turbo and ecu is still stock.

MLM

[ognam]

Once you've fixed the boosting issue, a remap would be a good idea.

[jamslau]

Just checked today, the boost hoses to the EBV is not connected, only control wires & vacuum hose to intake is connected.

[ognam]

[jamslau]

The car could be running on maximum boost, with the leaking cracked hoses saving the engine's ass from blowing up
The mechanic that did this for the previous owner must be lazy or something.... fortunately, it's not running lean, even at 1.4bar...

[jamslau]

Oops! Sorry I checked again & found that the hoses were connected to the EBV. so I'm gonna service the EBV & see, also will install 1 or 2 manual boost controllers to allow selection of 0.8, 1.0 or 1.2 bar

[ognam]

If you're going to install a manual boost controller, you don't have to service the ebv because it will be useless. Althought you need to blank off the pipes and leave it plugged in so it doesn't come up as an error?

How can u select boost levels by installing 1 or 2 manual boost controllers? I only know electronic boost controllers to achieve different boost settings.

[jamslau]

For multiple preset boost, I will connect 2 manual boost controllers in parallel, each set to a fixed pressure. Then use 12v solenoid valves to choose which controller/boost setting to use & turn off the other 1.

[jamslau]

At the moment, I'm still using the short side exhaust, power output is normal (from dyno readings) or psychologically gotten used to it.
I'm driving with an eye on the boost meter, full open throttle is still 1.4 bar but using right foot boost limiter
intake hose (after intercooler) has cracks/leaking.
Next step is installing manual boost controllers, then replace/fix the hoses.
0-100kmh is still 8s, possibly due to clutch slipping.
Getting 350-380km per tank RON95
Still driving around

[Kelv27]

For multiple preset boost, I will connect 2 manual boost controllers in parallel, each set to a fixed pressure. Then use 12v solenoid valves to choose which controller/boost setting to use & turn off the other 1.

This has got to be the most complicated boost control setup i have ever heard. James, why bother running 2 parallel PRV's with solenoid valve switching between the 2?? With the amount of money you're gonna spend buying all that rig, you might as well just buy an electronic boost controller, which can alternate between presets at a push of a button. Much tidier setup and less points of failure. The more vacuum hoses you use, the less accurate your boost control is going to be.

[ognam]

These are one of the more affordable EBCs around:

http://www.ebay.com/itm/2012-version-HD ... 35b9687a98

I've used them before too. You can set the boost in-car without having to manually set it in the bonnet.

[ognam]

If you could stretch your budget a bit, go straight for the Greddy Profec B-Spec II. These allow you to fine tune your boost characteristics and has a solid solenoid. Probably one of the better mods on my coupe now.

[jamslau]

Not complicated lah,(also I'm an electronics engineer)

I just bought a MBC to test http://www.aliexpress.com/snapshot/211750173.html
It'll be nice to have electronic controller but I don't need to change settings often, I'll be happy with 0.8 & 1.0 selection. Also, I like cheap low tech solutions like MBC, (less electronics, more reliable)

[jamslau]

Manual boost control is very simple...
http://www.turbosmartusa.com/technical- ... tallation/

[Kelv27]

Maybe i should rephrase this. Not doubting your capabilities as an engineer, just that it seems like you're reinventing the wheel. I can understand what you're trying to do but the additional vacuum hoses required to achieve what you are wanting to do is unnecessary. If its cheap, don't expect it to be reliable.

If you're adamant on using a manual controller with switchable preset boost levels, why not go for a dual stage manual controller? I think Raitag has one for sale

[jamslau]

Thanks for your advice Kelv,
Well, in this case, Because a MBC is a simple pressure valve (containing a spring & a ball) that opens the wastegate when pressure exceeds 1bar, so it would be quite reliable & robust.
I'm not trying to build a race car, only a working daily driver.
I do have to keep a tight budget, so I can maintain & complete my other project cars (1974 VW bus, 1966 fiat 850 sport coupe, 1968 fiat 850 coupe)
also wife & 2 kids & house....
Money is not easy to earn & prices have skyrocketed...
So if I can fix a problem with RM100, I won't spend RM1000 to do it with extra fancy features... Not that I don't want, but I'm not rich yet...
I do spend on the important stuff, since buying the car in Sept 2012 till now (4 months) I have done RM8000+ worth of work on it, it's now at the aircond shop to sort out oil contaminated system (more $$) ...

[Kelv27]

Got ya James. We all have the same problems and dilemmas

How ironic. I have aircond issues today too.

[newbie]

Well, in this case, Because a MBC is a simple pressure valve (containing a spring & a ball) that opens the wastegate when pressure exceeds 1bar, so it would be quite reliable & robust.

how does the MBC opens the wastegate when pressure exceeds 1bar? and how to determine how many bar until the wastegate opens?
Newbie here =)

[Kelv27]

As mentioned, theres a steel ball bearing and spring in the manual boost controller / Pressure Releasing Valve. The bolt that screws in and out controls the tension of the spring that pushes the ball bearing. The more you screw in, the harder the spring compression that pushes the ball to cover the pressure coming from the vacuum inlet. If you are setting it to 1 bar, it just mean that it takes 1 bar of pressure to overcome the tension of the spring.

[jamslau]

Yes, as you accelerate, the turbo is an air pump, air pressure increases until it's strong enough to push the ball against the spring, that will release some air to push the waste gate open & reduce the amount of exhaust going to the turbo. Therefore lowering/maintaining the pressure at the preset 1bar. You need to install a boost pressure meter to see what's the preset pressure.

[jamslau]

http://www.tercelreference.com/tercel_i ... heory.html

Garrett turbo engineer explains why turbo does not need back pressure, means larger is better after the turbine..
Before turbine requires higher velocity, so optimum size must be selected to get fastest spool without loosing top end. Too big will result in slower spooling & more lag.

[ognam]

Good article James. Explains how our stock manifolds are ready to make huge power. Albeit all the cracking issues.

Back to your case. Have you tried resetting your ecu after doing your exhaust mods? Disconnect your battery for 10 minutes or so, hook it back up and see what happens. Also consider getting another chip in there ie. Gtec 1. It's quite affordable. I feel the stock chip is quite limited in producing more power no matter what exhaust you slap on the car.

But then again, what deadlock mentioned way earlier in the thread could be possible. Other things that happen to fail coincidentally.

Did you have a cat before the exhaust job? Decatting a coupe with a standard turbo may shorten the life of your turbo seals. Especially at this age. But a turbo seal refurb with 360 degree thrust bearing will be an improvement in reliability.

[raitag]

u don't pump gas, u compress it... u pump liquid... so turbo is an air compressor... sorry, cannot resist...

[jamslau]

In that case, why do we say "pump your tires?" Next time must say " I compress air into my tires!"

[ognam]

Turbo your tyres!

[jamslau]

Update: replaced leaky intake hoses (after intercooler), now boost is faster but its uncontrolled! shoots up higher than 1.5bar! I Installed Manual boost controller but still can't reduce the boost pressure.... Something must be wrong with the wastegate actuator, so I pumped some air into the hose for wastegate & heard a hissing sound.
Where can I get a new actuator? What's the price?

[newbie]

Got mine sorted out at Tong Turbo, bring your faulty one there they'll get new diaphragm and what not in. Sudah lupa, was it RM3xx?

[jamslau]

Can I have TongTurbo contact? Thanks

[ognam]

You might want to try adjusting the screw on the actuator first and see if that works. Although if it's hissing, then maybe it's kaput.