How do you know if it is a HC engine or not?
Discussion
Useful post earlier in the month:
wheeljack888 said:
Mines a 1996 4.0HC and at the rollers it produced 198bhp at the wheels, an estimated 235 bhp at the flywheel. So if its 202hp at the wheels I would be very happy! But if its estimated for the flywheel I would be a little dissapointed. If so it could be a worn cam because HC's do have double valve springs and an aggressive lobe profile, this can therefore expected to have a shorter than normal life. I took my engine apart last year, which had done 45k, and the cam was looking a little worn on the hardening, but all measured up OK, I expect it to live for another 10-15k but thats potentially 2 years motoring for me! And hopefully by then I'll have my 4.6 that I'm very slowly building.
If your interested I can confirm the following differances over standard 3.9 RV8s for my 4.0 HC (maybe slightly different on others):
TVR435R/M camshaft
Vernier camshaft sprocket and duplex roller chain
Double spring valves
Machined pockets in piston crowns for valve clearance
Standard diameter but Waisted Inlet Valves
I'm assuming shorter valve guides to allow for higher lift.
The heads have been machined to accept double springs but are unfortunately not ported though.
So the short of it is, if you want more power the double springs & valve cutouts will allow you to have a much more aggresive cam than normal 4 litre Rover V8's.
Cheers
Phil
>> Edited by wheeljack888 on Sunday 9th April 20:04
brummiewedge said:
Hi Guys, is there a way of telling whether a 4.0 is a HC engine or not?
Cheers.
It usually has HC on the engine and of course on the factory paperwork (can be obtained from TVR for a fee).
Think of the "HC" badge as something akin to the mercedes "AMG" badge. Ok, so the badge might be considered flashy by some, but, to the true enthusiast, HC is a mark of performance over and above the norm.
N
shpub said:
Does anybody have compression testing information? That would sort out the boys from the toys.
Boosted.
No it wouldn't as HC in TVR land is NOT High Compression... but HiLift Cam. Indeed some HC specs I have seen have a lower CR than a plain 4.0 and vice versa.
Then is there really any noticable performance difference?
Boosted.
brummiewedge said:
Well i have got Double valve springs, i pulled the engine out today and checked while i was at it!! says 9.35:1 on the block.
That just means they bought a 9.35:1 bottom end from Rover. If the heads are stock volumes then that's about what your c/r will be assuming they used stock gaskets and pistons (which they probably did).
Boosted.
brummiewedge said:
Well i have got Double valve springs, i pulled the engine out today and checked while i was at it!! says 9.35:1 on the block.
Good start - what about the other stuff mentioned by 888? Sounds like you may well have a high lift cam engine (HC) but there again... Are you just interested or is there another reason?
Agree with what 888 posted, mine was I beleive the developement mule for the HC and was sold in the V8S as a 'gas flowed' option. The added benefit to mine being the test mule was it was fully and dynamically balanced too, apparently quite rare for a TVR engine, not sure many if any other HC's were tho.
One of the main benefits further down the line with a true HC is upgraded cams can be accommodated with little or no other modifications (vernier pulley, pocekting pistons, recessing springs etc) not sure a boggo 4ltr could do it so easily.
One of the main benefits further down the line with a true HC is upgraded cams can be accommodated with little or no other modifications (vernier pulley, pocekting pistons, recessing springs etc) not sure a boggo 4ltr could do it so easily.
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