WTB: 4B12 exhaust manifold

[bumblebee]

Exhaust heat wrap is perfect to reduce waste heat under the bonnet.
Cooler under the bonnet is the more power you will get.while your at it. Do your radiator hoses also

[burfadel]

It would help with insulating it if it is double walled, but it would only likely reduce it not eliminate it. Unless you can say you can keep your hand on it after an hour driving!

[bumblebee]

With my extractors wrapped i can touch them after a days solid drive and not get injured

[burfadel]

I painted the 4B12 stock extractors with high heat paint, let it dry, cured it (with gradual increase of temperature), and wrapped it with thermal wrap. I fitted it today, luckily it came with the 4B12 bracket from the wreckers which was good, I used the downpipe from the 4B11 manifold as the bottom part is identical. The 4-1 street extractors has the same mounting position as the 4B12 manifold, but not the 4B11. This may be further indication that it's really for 4B12's.

The car sounds different. The 4B12 manifold don't look like they're equal length, the 4-1 street's are. I noticed improved feel in the CVT typical range, say 1000-2300 rpm, but as you get higher than this the 4-1 streets seem to perform better. The 4-1 streets would be great for manual cars which is the claim anyway. I did do a small drive yesterday and repeated the same route today, and because of time of day the temperature was about the same.

The 2.0 L engine is the 'main' engine, it seems this manifold was designed specifically for it but was changed at the last minute due to the dual cat issue etc overseas. Fitting the clamshell to all the 4B11's is probably cheaper than the stock 4B12 4-1 extactors, but I guess it probaby zaps the performance of the 4B12 engines too much.

[bumblebee]

I love my 4-1 on my manual
Sounds awesome. Gives a nice growl and with the Merlin Tune its a new car

[Mooman]

As taken from a 2008 service manual, the only differentiation they make is for California vs Federal spec., not 4B11 vs 4B12. Of course this could also be that in 2008 all trim levels only had the 4B11 engine.

I still find it confusing why Australian cars have the Federal style front and centre pipe arrangement but yet have the California spec. manifold.

Maybe it was a cost cutting exercise or possibly a de-tune in order to differentiate the 4B12 performance further.

Either way I'm glad you found increased performance for CVT's as they need all the help they can get, just a shame it wasn't like that 'out of the box'.

[burfadel]

It is strange we get the Californian manifold here on the 4B11's, assuming the rest of the US actually has the federal spec 4B12 (Australia) manifold. In any case, it seems to be tuned for the 2.0 L CVT with the small primaries, it would be disadvantageous with 4B12 manuals you would think. Don't know what they mean by SUS pipe type, as far as it looks the 4B12 manifold is a 4-1 extractor. Maybe all 4B11's around the world get the clamshell manifold now, it would probably be cheaper to make and having it for just one state of one country wouldn't be cost effective either you would think. This includes the different mounting hardware. The 4-1 streets are basically a tuned length version of the 4B12 manifold with larger primaries. so it would let it breath easier with the higher revs. It would be interesting to know the difference in the normal CVT power range between the 4B12 SUS pipe manifold (extractors), and the 4-2-1 Supercircuits or RPW's, or even the 4-1 Race RPW's (either version). Although the 4-2-1 would be better in theory they have large pipes that probably benefits the 4B12 manuals more.

[burfadel]

Did some more driving today. Under around 3000 rpm it's definitely better than the 4-1 streets and especially the 4B11 manifold (the streets from memory were better than the 4B11), but you lose it in the high end. It probably performs not dissimilar to the 4B11 manifold above 3500 rpm. I think the main difference is the size of the primaries, they're tiny on the 4B12 manifold, I can imagine with the larger engine capacity of the 4B12 that the loss would occur well below 3000 rpm which would suck!

It would be interesting to know the difference between the 4-2-1's and the 4B12 manifold on the 4B11, seeing as the 4-2-1's also have large primaries.

[Mooman]

That's the problem with the aftermarket, they always focus on the end number so they can say more power more torque on a dyno without taking into consideration the drive-ability.

Imagine if someone bought out an extractor with similar narrow primaries as a replacement for clamshell type, They would be ridiculed despite the fact it would have useful real world properties.

But I still think if you have a 4B11 CVT you should definitely try to put in a 4B12 manifold as it makes the CVT more useful and less of a liability/embarrassment.