Turbo kit

[Grant]

Figure 5. Cast manifold with a divided turbine inlet design feature

Figure 6. Welded tubular manifold with a divided turbine inlet design feature

A design feature that can be common to both manifold types is a "DIVIDED MANIFOLD" , typically employed with " DIVIDED " or "twin-scroll" turbine housings. Divided exhaust manifolds can be incorporated into either a cast or welded tubular manifolds (see Figure 5. and Figure 6.).

The concept is to DIVIDE or separate the cylinders whose cycles interfere with one another to best utilize the engine's exhaust pulse energy.

For example, on a four-cylinder engine with firing order 1-3-4-2, cylinder #1 is ending its expansion stroke and opening its exhaust valve while cylinder #2 still has its exhaust valve open (cylinder #2 is in its overlap period). In an undivided exhaust manifold, this pressure pulse from cylinder #1's exhaust blowdown event is much more likely to contaminate cylinder #2 with high pressure exhaust gas. Not only does this hurt cylinder #2's ability to breathe properly, but this pulse energy would have been better utilized in the turbine.

The proper grouping for this engine is to keep complementary cylinders grouped together-- #1 and #4 are complementary; as are cylinders #2 and #3. Because of the better utilization of the exhaust pulse energy, the turbine's performance is improved and boost increases more quickly.

 

 

Heres a little about it .. Basically its all about utilising all of the exhaust energy of an engine rather than having "waste" like in a normal set up ...

 

The gases from 1&4 hit the bottom of the turbine in a contineous cycle and the same for 2&3 .. More efficient in short .. & better spool times ..

 

Let me konw if you want some more night time reading/watching as have a few links

[Krzys]

That's cool! I even learnt something! Light/night time reading is welcome too!

[Grant]

Good little bit here too robbed off wiki

 

Twin-scroll or divided turbochargers have two exhaust gas inlets and two nozzles, a smaller sharper angled one for quick response and a larger less angled one for peak performance.

With high-performance camshaft timing, exhaust valves in different cylinders can open at the same time, overlapping at the end of the power stroke in one cylinder and the end of exhaust stroke in another. In twin-scroll designs, the exhaust manifold physically separates the channels for cylinders that can interfere with each other, so that the pulsating exhaust gasses flow through separate spirals (scrolls). With common firing order 1-3-4-2, two scrolls of unequal length pair cylinders 1-4 and 3-2. This lets the engine efficiently use exhaust scavenging techniques, which decreases exhaust gas temperatures and NOx emissions, improves turbine efficiency, and reduces turbo lag evident at low engine speeds.^[34]

[Krzys]

Sweet, sounds quite suited to VTEC engines then! It's like it was meant to be!

[Grant]

I think they are mate yeah ..

 

Well the EVO has variable valve timing too .. Not sure on the history of the twin scroll and whether they were designed for the 4G63 or not ..

 

But they do seem to be a good shout !!!

[Krzys]

I bet anyone who owns or has driven a boosted Honda feels the OEM set up is somewhat lacking

[Grant]

I bet anyone who owns or has driven a boosted Honda feels the OEM set up is somewhat lacking

 

Yeah defo ...

 

For me, the best set ups will be the ones that complement the charateristics of the honda engines though ... So not a balls out GT35 or something stupid, but an improvement of power up top and more notabely, an increase in mid-range usable power ..

 

Of course, retaining vtec too

[Krzys]

Oh yes!

 

I had thought about cams and valve springs too but they probably wouldn't be necessary for going down the boost route, they shout more N/A to me.

[Grant]

Oh yes!

 

I had thought about cams and valve springs too but they probably wouldn't be necessary for going down the boost route, they shout more N/A to me.

 

I think there are gains to be had with doing them ..

 

Just depends on how far you want to go ..

 

At the end of the day, its all about your target and your budget .. Cams and springs is going to be 3-400 sheets .. Thats an IC, P30 & probably a fuel pump too ..

[KiNK43]

You can mount a twin scroll turbo to a single scroll mani it'll work fine. Lacking some of the benefit of twin scroll I'm sure.

Yeah the whole n/a thing ain't cheap.

I bought all my bits bar gaskets etc used. Then a remap still over 500 quid really. For 20hp I do love it tho. I've said it before for twisty b roads any more power in an eg would be suicide if you ask me.