1. Extra air (to raise compression hence give easier ignition, and for more complete combustion) and
2. A halved accelerator travel (=smaller fuel input) during acceleration
3. Less time spent during acceleration because there will be more pickup power.

The single Surbo or Twin Surbo can be used for diesels, with Twins requiring more air intake space (11 inches in a straight line, vs 6 inches for the single Surbo) and better matching the narrow rpm range of diesels.

Testimonial: Proton Wira 2.0D

The Citroen Jumpy 1.9 diesel was fitted with the Twin Surbo, and performance in every gear was satisfactory. Even when carrying a half-ton courier load, power was adequate. It's great to have a faster vehicle to hurry urgent packs too. The main difference over the single Surbo installations was the instant response when moving off from idle. As far as possible, we think that diesels should go with twins for maximum power (Twins are stronger between 2500-3000 rpm).

The '00 Hyundai H100 diesel van was a good example of a hardworking Surbo diesel. With a handy rpm meter, this was easy to aim. Red line was at 4000 rpm, but the tach swung to 4500 rpm with the accelerator pressed only halfway. The owner was quite happy with the new-found pulling power. He showed me some timber door brochures, and right behind us was a pile of doors he was trading in. One door was as heavy as one person, and that was quite a load, he said, and was the reason why he looked me up.

A '99 H100 2.3 diesel bus had emission problems. The owner had been fined for black smoke. His mechanic turned the fuel mixture to emit no smoke, but much power was lost. With the Surbo on, power was restored significantly.

The Isuzu diesel 3.6 with a 14 foot bed is the largest diesel both in terms of cc and weight with a Surbo so far. The owner, being very particular about black smoke, had already tuned the engine to emit none, but at idle during warming up, he had some white fumes. With the Surbo, this was the first thing he made off to check, and the white fumes had disappeared. Power was ok for him, and in view that all of his other trucks were turbo diesels. The big capacity was no problem, as the original 750 rpm at idle was maintained.

The Nissan Urvan 2.7 diesel bus had the twin Surbos directly replacing the pipe from the airbox to the pipe leading to the manifold. Before driving off for testing, the owner revved the engine (using just part of the accelerator travel) at standstill and was happy that the engine could go to between 4000 to 5000 turns per minute, and said that before the Surbos it could do only 3000 rpm. It was later also easier to jump to a higher gear sooner, enabling relaxed or even lazy progressions skipping gears, like going 1-2-4. I even saw him using 5th gear on our usual 2nd gear runway--just to really test the product.

The Renault Kangoo 1.9 with twin Surbos performed almost just as well. The owner commented that black smoke was no more visible in the mirror during driving, and confirmed it at idle by pressing the accelerator while I observed standing behind the vehicle. No trace of smoke at all.

Another Kangoo owner with a Twin Surbo made a u-turn in second gear and dropped to 20kph, and said the low rpm power had improved--previously he had to change to first gear for such a manoeuvre. He also managed to climb car park slopes in second--with no Surbo he had to change to first gear. Gearchanges upward were smoother and quicker as the greater air pressure in the engine ensured that the rpm stayed higher for longer when the accelerator was eased off during the gearchange.

Also fitted with Twin Surbos are the Toyota Hiace 2.8 diesel and the Corona 2.0 diesel taxi.

The 1993 Toyota Hilux 2.4D pickup had better pickup with a Surbo in the airpipe. The owner, Jude, said that black smoke was cut by half and since he did not have to take his eyes off the road to look in the mirror for the fumes, it was safer to drive. Fuel economy improved by 10-15%.

The owner of a 2001 Citroen Berlingo 1.9D said that before the Surbo, he could barely get to red line (5000 rpm) on the rpm meter with aircon on in first gear. With the Surbo, he could do that even in 4th gear, and just pressing the accelerator partly. The engine became smoother too.
He got back a month later to put on a second Surbo for a Twin.

The feedback regarding the first Surbo was:
1. Higher top speed--he could hit 140 kph with aircon on easily, and there was more speed up there, and this was better than the before-Surbo top speed of 130 kph with aircon.
2. Consumption remained the same despite hard driving all the time.
3. No more black smoke during cold starts.
4. Less noise and vibration during cruising and acceleration.
5. Better pickup. Previously, in first gear, there was one car length between the Berlingo and a friend's Mazda 323. With the Surbo, that was cut to half a car length.

The identical Peugeot Partner diesel car-van was also fitted with a Surbo. Once past the slow initial start at low revs in first gear, typical of diesels, the tachometer swung easily to 5000rpm with less that half throttle, and the vehicle was very petrol-like.

Also on the list is the '00 Nissan Cabstar. The Surbo was fitted under the driver's seat. After one run, the bolt under the accelerator (which was limiting fuel and unfortunately rpm too in order to prevent black smoke) was adjusted as that there could be more accelerator travel. With more air from the Surbo and more fuel, higher rpms could be reached without spewing black smoke. 80 kph could be reached easily in spite of overloading the truck's tall box cabin to the roof with dense plastic.

The '02 Toyota Liteace diesel with the engine in front also got one Surbo. It was fitted in the outlet of the filter box, and the customer reported an additional 50 km per 3/4 tank, beside the extra pickup power.

Surbo On Turbo Diesels

A VW Caddy turbo diesel van was driven by another happy customer for leisure. 0-100 kph was cut from 14 to 13 seconds with one Surbo. After that, the Twin Surbos made it even better to drive, with a lighter accelerator.

The Mercedes Vito 110 CDi turbodiesel van, when Surbo-equipped had a very long and breathtaking third gear like many petrol turbocharged vehicles. Owner reported 50 km more mileage per tank.

For the Mercedes Vito 112 CDi passenger van (automatic), even with the gearbox left in D mode, surges were very evident from standstill. This is because the Surbo's precompressed air increased the exhaust air flow, so it was spooling the original turbocharger (driven by exhaust gases) from a lower rpm than normal, resulting in a very satisfying drive that even petrol cars cannot match. Thus the Surbo is a good way of reducing turbo lag.

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