2.0 or 2.2 TB on a 1.8

kroz123 · Post by **kroz123** » Fri Jun 06, 2008 4:18 am

Hey guys it's been a long time since I don't post on the forum, well I'm back.

I have a ? for you guys to see what you all think.

Well I have an Optra 1.8L and I wanted to go for the larger TB is it worth it.

Is there any gain in it?

Thanx

Kroz123

Pir0 · Post by **Pir0** » Fri Jun 06, 2008 7:21 am

I know this wont apply to all TBs, it's got a lot to do with the whole intake system, the size of the plenum at the start, the size of the tb, and the width and length of the runners, but, was reading something really interesting ont he astramk2 forum, and a fella got a larger tb for his redtop engine, and this is what happened.

It made it more drivable he said, as the torque was increased below 4000 rpm. But for top end it dropped off quicker, meaning he actually dropped BHP when installing it, but gained torque at the lower rpm. Absolutly useless for racing or pushing the car as the car rarely drops below 4krpm if you're pushing it, but he said it did make it a lot more smoother and drivable.

kinkyllama · Post by **kinkyllama** » Fri Jun 06, 2008 11:12 am

The 2.0/2.2 TB is probably the same as yours.

AntDX316 · Post by **AntDX316** » Fri Jun 06, 2008 12:21 pm

i read getting a larger throttle body gives torque later on the rpms

BosnianLanos · Post by **BosnianLanos** » Fri Jun 06, 2008 12:43 pm

My guess is that the weird HP readings can be attributed to his stock exhaust. With the new manifold and TB, a lot more air was entering the engine, building up back pressure. For our engines, back pressure is a good thing (helps with scavenging, ect.) With the heightened back pressure, he was able to bump his lower-RPM torque numbers up, but his higher-RPM power numbers suffered has the restrictive exhaust most likely caused too MUCH back pressure.

I believe that if he put on a freer flowing exhaust, his torque gains early in the range would most likely drop, but the numbers up high would show improvement over baseline.

kroz123 · Post by **kroz123** » Fri Jun 06, 2008 4:39 pm

kinkyllama wrote:The 2.0/2.2 TB is probably the same as yours.

so Kinky for you it won't give anything?

I also have a full cat-back exhaust 2.5" for the turbo but I changed my mind on putting the turbo due to having overhauled the whole engine.

So for this engine I won't put a turbo on it.

Arvin

BosnianLanos · Post by **BosnianLanos** » Fri Jun 06, 2008 4:50 pm

But yeah, to agree with Kinky, I'm pretty sure the 1.8, 2.0, and 2.2 have the same throttle body.

Going from 1.6 to the larger TB allows for a HUGE increase in size.

I'm working on getting my intake manifold TB flange port-matched to the new larger TB. We'll see how this goes!

MMamdouh · Post by **MMamdouh** » Sat Jun 07, 2008 12:36 pm

the 1350, 1500 and 1600 got the small TB... the 1800, 2000 and 2200 got the big one

MMamdouh

kinkyllama · Post by **kinkyllama** » Sat Jun 07, 2008 8:32 pm

kroz123 wrote:
kinkyllama wrote:The 2.0/2.2 TB is probably the same as yours.
so Kinky for you it won't give anything?

I also have a full cat-back exhaust 2.5" for the turbo but I changed my mind on putting the turbo due to having overhauled the whole engine.

So for this engine I won't put a turbo on it.

Arvin

Yeah it's the same TB. Only thing is, some nubbys and leggys have this, A bump inside the TB I think just after the plate. If yours has this you can grind it down. Also there are easy ways to DIY and polish it up.

2.5" cat-back probably won't kill your TQ without a turbo. It's what I used to have on the lacetti and what I'm probably going with on my 2.0 lanos (2.5" header back) but am running a resonator, one hi-flow (easily removable) CAT, and muffler.