Driving characteristics 4.0 v 4.5 v 5.0 - after 250-300bhp

Driving characteristics 4.0 v 4.5 v 5.0 - after 250-300bhp

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Discussion

Andav469

958 posts

138 months

Monday 8th April 2019
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LongBaz said:

Drives nicely and quite........but all hell lets loose when you hit the right hand peddle.
Great numbers, but exactly why I didn’t go Turbo, that power curve in a light car is severe, 200 bhp increase from 3-4K rpm, I thought mine was a handful lol

AceOfHearts

5,822 posts

192 months

Tuesday 9th April 2019
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QBee said:
You might squeeze 250 bhp out of a 4 litre. You won't get 300 bhp without spending the national debt on wildcat heads etc etc.
Turbocharging or supercharging will get you to 330 bhp with little difficulty. The 400 is a nice revvy engine, as was the 430 in the early cars.
The 450 and 500 are more grunty.

The 5 litre engines are about 280 bhp in factory guise, but can be improved to 300 to 360 bhp with liberal use of wallet. The most noticeable difference I found was the serious increase in torque over the 4 litre - they just have so much more grunt.

And that's your quandary - keep it standard at 280bhp or "improve" it, because none of the improvements are cheap, or if they are they add 2 bhp and you can't tell the difference. In my humble opinion, no improvement is worth the effort for less than 20 bhp minimum.

Can I just dispell one myth - "turbo lag". A TVR Rover V8 is not a 1980s Rally Audi Quatro. If you turbocharge your engine it will mostly feel like the normally aspirated engine, just a bit faster. At the low pressure levels we use, there is no turbo lag. The main difference is that the max torque is a much bigger number, but it has a much narrower band.

If you drive my car without knowing it is turbocharged I doubt you would actually know it was turbocharged, apart from the "pssst" on changing up a gear, as the dump valve dumps the excess pressure. It feels just like a normally aspirated car, but with the power and torque in a bit narrower band.

What I am saying is, if a turbocharged or supercharged 4 litre comes up for sale, don't turn your nose up with out trying it.
I think it depends on the car again, as my turbocharger is definitely easy to notice!

Noise and torque builds smoothly until around 3000rpm and then all hell breaks loose with noise, a huge increase in power and associated wheelspin smokin