New exhaust manifold + remap

Hi,

I just want to share with you two new mods I have done to my bella. In the last two weeks I had a new stainless steel exhaust manifold installed and remapped the ECU.

Manifold is hand made, laser cut stainless steel flange, stainless steel piping, welds are polished from inside, 4-2-1 type, 2 pre-cats removed, lambdas remained in place. Pictures are here:
http://kgb.alfaromeo-bg.com/gotcha/E...it%20manifold/

Pictures of original one are here in case somebody would be interested to see them:
http://kgb.alfaromeo-bg.com/gotcha/E...st%20manifold/

In a few weeks when funds allow, I will have main cat replaced by 200 cell racing one and the center section will be made of the same pipe diameter with one resonator. Supersprint backbox will be kept in place. I will wrap that manifold with thermal insulating tape as well to keep the gases as hot as possible for the flow proposes and keep temperature in the engine bay a little more reasonable.

ECU remap is fairly mild now, there is an option for more aggressive set-up but I will postpone the ECU fine tuning on dyno for later when the hardware work is all done. I plan to install variable intake manifold from 2,0TS as well.

If everything goes fine I might reach 145 - 150 bhp level till the end of year and I still have many more plans

looking good mate, bet she feels a lot more responsive now than with those twin cats in, i really wish alfa hadn't given us so many!

How does she sound with the new header? I had a straight thru racing header paired to a straight thru exhaust on my hyundai coupe and found the noise to be to raspy for day to day driving. Hope its not to loud for ya! Try and get a video or sound clip up if you can :-)

Looks really nice.

Originally Posted by marko

looking good mate, bet she feels a lot more responsive now than with those twin cats in, i really wish alfa hadn't given us so many!

How does she sound with the new header? I had a straight thru racing header paired to a straight thru exhaust on my hyundai coupe and found the noise to be to raspy for day to day driving. Hope its not to loud for ya! Try and get a video or sound clip up if you can :-)

The sound is more aggressive, but not too loud. When I hold steady speed, I almost can’t hear the exhaust, but during acceleration it is clearly there. There is some rough noise under the floor where the manifold connects to standard center part; the gases make some noise on the narrowing where the diameter changes, but this will be sorted out with new center part.

Nice thing is, that the sound is coming from under the bonnet and not only from the backbox like with all tuned Corsas and Polos with big backboxes.

Car is pretty responsive, but I don’t know how much of this is thanks to the exhaust and how much thanks to the remap. But the difference can be clearly feeled.

I will try to make some video over the weekend and post it on Monday.

i look forward to a video!

Tuned corsas lol, you mean ones wit oversized crap cheap bean cans on... Yak

Looks nice.

I see it is not heat-coated or heat-wrapped. It must radiate a lot of heat inside the engine bay.

Where are the two HEGO sensors from the (missing) light-off cats? Can't see them in the pictures.

Does the power output curve of the car seem changed in any way?

Originally Posted by alfasud.ti

Looks nice.

I see it is not heat-coated or heat-wrapped. It must radiate a lot of heat inside the engine bay.

Where are the two HEGO sensors from the (missing) light-off cats? Can't see them in the pictures.

Does the power output curve of the car seem changed in any way?

Manifold will be kept this way for about 2 months. Than I will have the cat + center part replaced and I will have the manifold wrapped in heat resistant tape. It was not available this week locally. And the manifold has to be removed to be wrapped anyway.

The two original lambdas are installed; they are just not on the pics. Some pictures were taken during the manifold manufacturing and threads for lambdas were not there yet. They are just behind the place where the 4 pipes connect in 2.

Two pre-cats are removed. They have meaning during engine warm-up only anyway, when the main cat is not hot enough to be effective. When the main cat warms up, two pre cats are not necessary to pass emission test. Their only job is to comply with EURO3 norm during first 3-5 minutes after start as they heat up almost instantly.

Power output is definitely changed, but don’t forget I got remap at the same time as well. Car pulls much stronger below 3,5k revs and doesn’t loose power after passing 6k. Pulls up to the limiter. Power delivery is very smooth, with no flat spots, but the final remap will be properly done during dyno testing when the exhaust and intake is finished.

I was looking for a stainless manifold for my 2.0 GTV.Only one i could see was the supersprint one,which looked very nice only they stoped making it some 18 months ago .
Had a quote to have one made and get rid of those pre-cats about £800.Needless to say i still have the standard one fitted

Originally Posted by marko

i look forward to a video!

Here we go:
http://kgb.alfaromeo-bg.com/gotcha/Exhaust/

Unfortunately I had only a compact camera available and it records sound in low quality.

ooof gotcha, sounds fantastic! sounds like you need to improve the intake a little tho, seems a bit slow at letting the revs drop off, might just be my imagination tho!

Originally Posted by marko

ooof gotcha, sounds fantastic! sounds like you need to improve the intake a little tho, seems a bit slow at letting the revs drop off, might just be my imagination tho!

Thanks

No, its not your imagination :-) I thought about this, I would like the revs to rise and drop more quickly and get better engine response, but I am not a big fan of sport air filters. Maybe in the future... I am thinking of sharpening engine reactions by lightened flywheel. My only worry is how drivable will the car be in traffic jams, when I just move in 1st. Will the engine stall? I don’t want to rev to 3k just to get going slowly. Any experience?

i have a titanium flywheel i got cheap on ebay and an uprated clutch and have no problems in traffic. it does sometimes seem to judder a little if only crawling but that is a rare occurance. all in all a very worth whilst mod IMO.

considered the autodelta flywheel and clutch kit? CLICKY CLICKY its a good spec and reasonable price. i would also suggest you do look into a sports filter, or, if you prefer, retro fitting the GTA intake system to keep noise down but improve intake

Originally Posted by marko

considered the autodelta flywheel and clutch kit? CLICKY CLICKY its a good spec and reasonable price. i would also suggest you do look into a sports filter, or, if you prefer, retro fitting the GTA intake system to keep noise down but improve intake

Autodelta flywheel kit is the one I am considering Actually Autodelta Europe is doing all the mechanical mods on my car http://www.autodelta.sk/ though they are not directly related to autodelta UK.

GTA intake mod might be interesting, but I thing the bottleneck would be the throttle body. I better finish my exhaust first and than plan the next steps :-)

marko, did you have your bottom end rebalanced after fitting the lightened flywheel? Mind you that the 2.0 TS has a big stroke and is thus vulnerable to second-level harmonic vibrations, that's why it comes with a balance shaft.

Ideally you could remove the balance shaft, lighten and rebalance the bottom end and you will probably gain an extra 10-15HP just from the missing loss of power to the balance shaft.

gotcha, I did something similar but I used a heat-wrapped manifold from a 156 2.0 TS Euro II engine without light-off cats. The HEGO sensors are exactly where you described, the main cat has been replaced with a 200cpsi metallic one, the 48mm stock tailpipe replaced with a 52mm one and the second (small) expansion box removed. The car gained +6HP (dynoed at the wheels) after being re-remapped but it felt a lot more powerful than just +6HP through the entire rev range.

Its best range is between 5200 and 7600rpm (tweaked cutoff) when the car seems to surge forward screaming but there is also some gain in the low revs below 3000rpm. I suspect that the high-rev burst has to do with the fact that both primary (4 -> 2) and secondary (2 -> 1) manifold pipes are considerably longer now.

Originally Posted by alfasud.ti

gotcha, I did something similar but I used a heat-wrapped manifold from a 156 2.0 TS Euro II engine without light-off cats. The HEGO sensors are exactly where you described, the main cat has been replaced with a 200cpsi metallic one, the 48mm stock tailpipe replaced with a 52mm one and the second (small) expansion box removed. The car gained +6HP (dynoed at the wheels) after being re-remapped but it felt a lot more powerful than just +6HP through the entire rev range.

This is my planned setup just the center pipe will be probably 54mm to fit the supersprint backbox that I plan to keep. Cat will be 200cell metallic as well. Center silencer will be replaced by a resonator box and the second (small) expansion box will be removed as well. Exhaust will be finished probably in the end of October.

if you dont remap the ecu, but install the custom exhaust manifold with the two lambda sensors as yours, there will be any problem?

My car is a 2.0TS 156 Euro3 but here in my country i think i only need the last cat to pass the emission test.

wow, they look really good!

they made a big messup with the design of the old one, the older 16vers have a design closer to your new one!

bet that sounds the nuts!

Originally Posted by gotcha

This is my planned setup just the center pipe will be probably 54mm to fit the supersprint backbox that I plan to keep. Cat will be 200cell metallic as well. Center silencer will be replaced by a resonator box and the second (small) expansion box will be removed as well. Exhaust will be finished probably in the end of October.

please post pictures of your project when is finished.

Good stuff! Nice to see someone doing some well thought out mods

Originally Posted by gotcha

Nice thing is, that the sound is coming from under the bonnet and not only from the backbox like with all tuned Corsas and Polos with big backboxes.
.

This is exactly how I feel with my car!

and mine, i