Why can't you get performance cams for diesels?

obi_waynne

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They are not tuned as much as petrol engines so there is less of a market for them but there are also technical reasons why you can't get diesel performance cams.

Diesel engines are quite low revving, so a performance cam will not provide as much lift as it would on a petrol.

On petrol engines the gains tend to come in at 4000-8000 rpm, and most diesel engines just don't hit this level or are just about to redline.

The principles behind a compression ignition engine, as apposed to a spark ignition engine are very different when it comes to tuning them, so things that work well on a petrol do not always work on a diesel.

Interestingly a remap on a diesel nearly always gives better fuel economy, whereas on a petrol engine this is very unlikely to happen.

That's not to say there is no benefit from a slightly longer intake/exhaust duration, but most performance diesel engines out there are designed to a pretty high standard.
 

Snorkky

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If you can`t get a cam for a diesel, there`s nothing to stop you using roller rocker arms that have been designed to increase valve `lift` by re-positioning the rocker arm pivot axis.

The only thing that you have to watch for is a piston top/head hitting a valve and that has to be checked as you assemble your engine and turn the crank by hand. Even if a piston does touch a valve, there are suitably experienced tuning engineering businesses that can machine out valve clearance into the piston tops.
 
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Fabia17

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Why can't you get high performance fast road or race camshafts for diesels?

Do they work on diesel engines or is there no demand for them?
Kent and Piper offer cams for diesels. My father had a Peugeot 306 years ago with a fast street cam in it and a remap, it was bonkers....
 

obi_waynne

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Those Peugeot diesel engines are phenomenally good, and seriously underpowered unless remapped.

It's interesting to know that cams for diesels are out there.
 

orca1911

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The 2.0 and 1.6 HDi engines from PSA have quite a following when it comes to tuning but the biggest fanbase is probably the VAG group. Their forums might be the only places where one can get some tuning info. People just go for vnt turbos and bigger injectors + remap by most part almost doubling the power, not many went for cams though but dual turbo setups were the most fun ones to see.
 

Ronbros

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check out Audi V12 DIESEL dohc twin turbo , banned from racing because they were TO FAST, compared to petrol/gasoline engines!
R-10 TDI
 
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Fabia17

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You can have your cams ground, but diesel engines rarely require a high lift cam, usually because they are turbo charged, and a turbo cam is designed for maximum efficiency working with the turbo. Changing your cam profiles could cause all sorts of knock-on and undesirable effects. Hope this helps.
 

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