P38 Rover V8s

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Henry-b
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P38 Rover V8s

Post by Henry-b »

Hello gents long time no see!

Anyway..

I have a Thor 4.6 P38 and the quoted power is 214hp and 407nm however the Gems is quoted as having more HP but less torque at 225hp and 380nm

Apparently though in America Land Rover got in trouble because the Gems didn't produce near the quoted power level from LR..

My question is does the Thor really produce less than the Gems or is there a mistake somewhere anyone had a P38 on the dyno?

Surely with the more efficient bosch motronic injection and revised intake it would produce more power than the old sagem system? :idea: :?:

Thanks

H



DaveEFI
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Re: P38 Rover V8s

Post by DaveEFI »

The long tract inlet system on the Thor is designed to maximize lower RPM torque, since it is fitted to a 4x4. The original Lucas injection which all the previous engines shared as regards the inlet design was originally meant for the Vitesse, a sports saloon.
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garrycol
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Re: P38 Rover V8s

Post by garrycol »

Yes the Thor produces a little less HP but a bit more torques.

Chicken Drumstick
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Re: P38 Rover V8s

Post by Chicken Drumstick »

DaveEFI wrote:
Fri Oct 08, 2021 10:50 pm
The long tract inlet system on the Thor is designed to maximize lower RPM torque, since it is fitted to a 4x4. The original Lucas injection which all the previous engines shared as regards the inlet design was originally meant for the Vitesse, a sports saloon.
I can see why they'd want a 4x4 to have good low rpm torque. But I've read the 4.6 Thor makes peak power at the red line.

"The Bosch engine is mapped in such a way that it produces maximum power when it hits the Rev Limiter, which is set at 5400 RPM."

Ref: https://www.tornadosystems.com/product/ ... or-engine/

Mine has been on a dyno (rolling road), but would seem to pretty much match this expectation.

I struggle to believe Thors make less power than a GEMS one from the factory, I suspect the Thor solution was the real answer in getting the power up, due to the legal action LR faced in the USA with the early examples.

A bit of a Google also suggest the Thor model is slightly quicker, which would back up the assumption that it makes either the same power or more.

1998 Range Rover 4.6 HSE Vitesse 0-60 mph 9.6 Quarter mile 17.1

1999 Range Rover 4.6 HSE 0-60 mph 9.4 Quarter mile 17.0

DaveEFI
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Re: P38 Rover V8s

Post by DaveEFI »

In terms of the electronics, I've no idea how good the Gems system is.

To do a real comparison between the inlet manifold designs, you'd need to use a properly tuned after market ECU with both (like say a MegaSquirt)

Peak power has really not much to do with a standing quarter mile figure (within reason) - it's the torque curve below that which matters for road use. Perhaps even more so with an auto. Different in a race car where you keep the engine on boil.

With the earlier Lucas systems - especially the 4CU flapper - there was quite a variation between samples. The 4CU tended to run weak at lower revs/moderate throttle openings. Perhaps to give the best lab MPG figures. On going MegaSquirt on my SD1, the big difference was the extra grunt at low revs - peak power being much the same. Wouldn't be surprised if this applied to the Gems too.
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