HC ECU on standard 4.0

[BillC99]

Whilst moving my ECU I noticed that the label said 4.0 HC. As far as I know my engine is not an HC.

1) Does anyone know if the ECU's are different?
2) How would I identify if my engine was an HC?

Any help appreciated!

[blitzracing]

At worse case it will only be the fuel map chip thats different, but you need to open the ECU and see whats written on the chip. Generally the biggest difference between the chips is the airflow scaling, depending on engine size, not so much small variations in tune, so if it runs OK, I would not worry about it.

[MikeTVR]

It's likely that your car is an HC as I understand that most of them were.

If your car has the original HC cam (and that's the only real difference) then you'll be finding that the engine isn't smooth below about 2200 RPM.

Mike

[SMB]

MikeTVR said:

It's likely that your car is an HC as I understand that most of them were.

What's your evidence for this comment? Many of the ECU's had things scribbled on them, but by this age so many changes could have happened, the only 100% answer is the eprom inside. Mine was labled hc on the outside in pen, It would be nice to think my 4.0 is an but I don't expect it.

[MikeTVR]

SMB said:

What's your evidence for this comment? Many of the ECU's had things scribbled on them, but by this age so many changes could have happened, the only 100% answer is the eprom inside. Mine was labled hc on the outside in pen, It would be nice to think my 4.0 is an but I don't expect it.

The only way to be 100% sure is to compare the cam lift with a standard cam, but as I said you'll gete a good idea of whether it's an HC (High-lift Cam) by how smooth the engine feels at around 2000 RPM.

Mine is labeled HC on the ECU and on the EPROM inside.

[K4TRV]

MikeTVR said:

The only way to be 100% sure is to compare the cam lift with a standard cam, but as I said you'll gete a good idea of whether it's an HC (High-lift Cam) by how smooth the engine feels at around 2000 RPM.

Mine is labeled HC on the ECU and on the EPROM inside.

Probably going to open a-can-of-worms..............HC "can and probably (IMHO)" means High Compression and not anything to do with the cam (sounds more plausible to me than just a High lift cam)!!!

Still, I've never bothered to look at my ECU, but during recent cam change for my '93 400, we saw double valve springs which indicated some elements of a HC engine. The other changes believed for an HC, which we could not view (money & time), are: Pocketed High Compression Pistons; larger valves (double springs) and ports, but no change to the cam!! Futher checks discovered the TVR cam specified for all 400's is exactely the same for all models from 93 onwards??!!

If you think you have a HC, then you need to inspect the pistons, ports and valves - seems logical?? I do wonder what advantage you would get with just a higher lift cam, other than a rubbish tick-over, if you didn't do a lot of work to the heads?? Likewise, keep the same cam, but make it breath through larger valves and a higher compression, sounds more HC to me!!

Just my opinion and not attacking anyone's beliefs/aspirations/egos - just so confused when HC is called a cam change only!!!

[captaintact]

One would normally think HC meant 'high compression' BUT in this case is DOES mean 'High Cam Lift'!

[SMB]

captaintact said:

One would normally think HC meant 'high compression' BUT in this case is DOES mean 'High Cam Lift'!

Correct, from memory an HC should have a high lift cam, a revised ecu map, double valve springs, pocketed pistons and double chain cam drive iirc. oh and a stick on 4.0HC badge on the plenum. Of course the easy things to change do not mean you have a real HC.

[rigga]

And if the cam has been changed at some point in its life, and at the age these cars are a lot have, then its a moot point calling them HC ..... mine is one such like .