TVR 4.0 HC Engine/auto box

koopsterman · Post by **koopsterman** » Thu Mar 15, 2012 10:39 pm

Can anyone tell me if a TVR 4.0 HC engine would function/behave with an auto box behind it, particularly at idle and just off idle, ie in traffic etc ??
Koopsterman

DaveEFI · Post by **DaveEFI** » Thu Mar 15, 2012 10:59 pm

No reason I can think of why it would be any different than other engines.
Unless the cam is so wild it can't idle reliably.

Of course whether it is a good match to an auto is a different matter. If it is only a three or four speed auto, you need a good wide spread of torque to avoid it disappointing too much.

kiwicar · Post by **kiwicar** » Fri Mar 16, 2012 9:59 am

Hi
there is no reason that the TVR engine should be any different to any other engine with an auto box. Match the cam and torque converter properly to the change points in the box and the axel ratio and it will be fine, get it wrong and it will be horrid!
To that end, if it is going into a light car then find an autobox from a similar weight car, if you stick a lumpy cam in the engine use a higher stall converter, if you have a very high axel ratio then have a torque converter with quit a high slip ratio at cruise, however if it has a moderate axel ratio and an overdrive have a converter with less silp.
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Fri Mar 16, 2012 10:45 am

It's a shame there was never a modern auto fitted to the RV8 - 5 speeds or more. The 5 speeder on my BMW is pretty good - it's a pipedream to fit one of those to my SD1. It can be controlled by an after market ECU. But the actual mechanics of fitting it are rather daunting.

koopsterman · Post by **koopsterman** » Fri Mar 16, 2012 5:42 pm

Thanks for the replies guys,the box is a ZF 4hp22 non electronic version from a Sherpa/LDV, and the convertor locks in 4th gear. The rear end gears are 3.73:1 and the vehicle is light (Austin devon Pick-Up ) do you think this combo will work ?
Koopsterman

JSF55 · Post by **JSF55** » Fri Mar 16, 2012 7:33 pm

What size back tyres? i'm running a 4.09 jag rear with 275/50x15 and that works out fine, pulls a little in gear on idle tho

koopsterman · Post by **koopsterman** » Fri Mar 16, 2012 8:37 pm

The tyres are 255/70 and are approx. 28" dia.
Koopsterman

JSF55 · Post by **JSF55** » Fri Mar 16, 2012 9:27 pm

Should work fine if the car is light enough

SimpleSimon · Post by **SimpleSimon** » Fri Mar 30, 2012 9:59 pm

Maybe a bit late but the HC 4.0 as a rather big cam for a standard autobox, if the cam is original its the same as fitted to the TVR500 engine and as quite a splashy idle, not helped by the fact that TVR chose to do nothing to the stock compression ratio to lump up the bottom end torque to counter act the poor low speed running of what i consider to be an over cammed almost stock 4.0 RV8

its OK in the TVR as the car weighs bugger all and masks the poor load speed torque

koopsterman · Post by **koopsterman** » Sun Apr 08, 2012 3:29 pm

Hi SimpleSimon, thanks for the input, the car its going in weighs bugger all - possibly less than the TVR, its an Austin Devon pick-up.
Do you think raising the comp. ratio would help ? or can you suggest any other tweaks ?
Koopsterman

SimpleSimon · Post by **SimpleSimon** » Sun Apr 15, 2012 2:16 pm

Pair of decent heads with reworked intake would not go amiss, also a raise in compression is a bonus too as stock is a bit on the low side for a performer