VHPD differences

[andy oliver]

As a matter of interest would anyone happen to know the mechanical differences between a 1.8 VHPD and the standard 1.8 K series?

Also,is there an option to fit a bike engine to an ordinary Caterham 5 or 6 speed gearbox?

[Red SLR]

Different head?

 

X777CAT

[CHRIS CLARK]

The VHPD (Very High Power Derivative) and the cooking 1800 'K'are about 69 ps apart.

 

1800 engine has the std. kit which has a plastic plenum, std 1800 cams, etc.

Claimed power is 124 ps @ 5,750 rpm with max torque of 122lbsft @3,000 rpm

 

The VHPD has mechanical tappets (instead of hydraulic followers). It has larger in & exh. valves and a ported head, forged pistons and a nitro-carburised crankshaft. It also has high lift cams, D2H TB's of PTP manufacture (well the latest incarnations do) and a reprogrammed MEMS engine management system.

 

Claimed power is 193 ps @ 7,500 rpm with max torque of 150lbsft @5,750 rpm.

[oilyhands]

The VHPD uses a hybrid cylinder head with the porting, combustion chambers and valves sizes of the VVC but with conventional cam arrangements above the waistline. It comes equipped with Piper 872 profile cams (280 duration, 10mm lift) and solid followers with appropriate caps, it uses Omega forged pistons which are fitted to 'better material' rods but still retain an interference small end, the crankshaft is Tufftrided rather then Nitro carburised.

 

Early incarnations used the Rover KV6 throbble botties on a rather tortuous inlet manifold, later ones use the PTP (Titan?) DTH throttle bodies. Recent work on a few VHPDs has shown that *some* have a little light porting around the inlet seats and exhaust seats and others dont. The cams are also not accurately timed with the standard pulleys.

 

Claimed and acheived output vary, but its generally accepted that these make between 185 and 195BHP.

 

Early and late engines use the MEMS ECU in modifed form.

 

Oily

 

Edited by - oilyhands on 26 Jan 2002 20:44:53

[andy oliver]

Many thanks for the very comprehensive info guys.So does a VHPD have standard length valve guides 'cos I was slightly concerned when I read the thread about the chap with high oil consumption possibly due to wear on shortened ones.Also,is the idea when fitting vernier pulleys, to set them zeroed in the same position as the standard ones and then get them fine adjusted on a rolling road?

Thanks again for the advice.

[oilyhands]

The VHPD/VVC and K16 have the same length guides, the shortneing occurs when the head is ported and the guide/boss protrusion removed. *All* the heads I do now use replacement full length but tapered Colsibro guides to eliminate the guide wear problem.

 

Fitting verniers is as you suggested, there is a comprehensive guide to marking (essential) and fitting verniers here. Save yourself some pain, the instructions are straightforward. If you know the lift at TDC which is ideal for your cams then you can adjust the cam timing yourself, let me know the cams, I'll give you the optimum lift at TDC, instructions on how to set the lift at TDC correctly are on the same page.

 

Oily

[andy oliver]

Thanks Oily.I have downloaded the appropriate web page as suggested.It's an ordinary factory VHPD about 18 months old so I assume the cams are Piper 872 as per your posting.

[oilyhands]

For the 872s try 130 thou lift at TDC for the inlet and 110 thou lift at TDC for the exhaust. This should bring the torque up just about everywhere. It's worth noting what the lift at TDC is *before* removing the existing sprockets and swapping to the verniers just to see how far out the current timing is. One done quite recently had 90 thou on the inlet and 130 on the exhaust, both cams quite badly retarded.

 

When fitting the verniers initially, retard the inlet vernier by 10 degrees and advance the exhaust vernier by 10 degrees, this will minimise the lift at TDC and make your initial valve timing very safe.

 

Oily

[Petrolhead]

When did the throttle bodies change. what year?

 

Still looking for a newun sad.gif

[Petrolhead]

When did the throttle bodies change. what year?

 

Still looking for a newun sad.gif