Difference of bhp between v8 450 of tvr and 4.6 v8 of p38
Discussion
Hello, I write from italy and my english is very bad. I see that the 4.6 of range rover p38 have 222bhp and the 450 of tvr have 285 bhp. the two engine have two different type of injection (my friend installed a 14cux with a camshaft of 3.9 in to a 4.6 of p38 and than the engine from start to 4000 rpm run good, than it was struggling). also the tvr have a pair of exhaust manifolds that are better then the manifolds of P38. But for me is impossible that an injection and a pair of manifolds changes the power of 63 bhp. also i'm interest to know the camshaft that have the tvr 450 and if there are difference between the heads of p38 and heads of tvr (vavles size different??).
p.s. i aso see that the 3.9 of range rover have 190bhp and 3.9 of chimera low compression have 240 bhp... and here what change??? but tis is another story
p.s. i aso see that the 3.9 of range rover have 190bhp and 3.9 of chimera low compression have 240 bhp... and here what change??? but tis is another story
My TVR has a standard Range Rover P38 4.6 engine and standard Range Rover cam.
We just blew on it and it makes 395 bhp.
Magic
It might just be worth checking if Range Rover's quoted bhp numbers are at the flywheel, or at the wheels.
TVRs factory quoted numbers are definitely exaggerated by about 25% and are at the flywheel.
Bhp at the wheels is generally 18-20% lower than flywheel bhp.
I was very surprised when I doubled the bhp (at the flywheel) from an engine that was supposed to make around 200bhp, by adding only 0.5bar to the air intake pressure. It is supposed to need at least 1 bar to do that.
Get your crayon out, draw your own conclusion.
We just blew on it and it makes 395 bhp.
Magic
It might just be worth checking if Range Rover's quoted bhp numbers are at the flywheel, or at the wheels.
TVRs factory quoted numbers are definitely exaggerated by about 25% and are at the flywheel.
Bhp at the wheels is generally 18-20% lower than flywheel bhp.
I was very surprised when I doubled the bhp (at the flywheel) from an engine that was supposed to make around 200bhp, by adding only 0.5bar to the air intake pressure. It is supposed to need at least 1 bar to do that.
Get your crayon out, draw your own conclusion.
Naldi Lorenzo said:
Does anyone have a disassembled head of a 4.6 v8 of TVR? Is it possible to know the diameter of the exhaust valves and the intake valves?
Thank's
Just using a tape measure on a late 4.6 head the valves are roughlyThank's
Inlet 39 mm
Exhaust 34 mm
This is the standard valve size for 4.0 and 4.6 engines I believe.
It’s only the 5.0 cars that have bigger valves as standard.
A quick google search will give you precise details.
QBee said:
My TVR has a standard Range Rover P38 4.6 engine and standard Range Rover cam.
We just blew on it and it makes 395 bhp.
Magic
It might just be worth checking if Range Rover's quoted bhp numbers are at the flywheel, or at the wheels.
TVRs factory quoted numbers are definitely exaggerated by about 25% and are at the flywheel.
Bhp at the wheels is generally 18-20% lower than flywheel bhp.
I was very surprised when I doubled the bhp (at the flywheel) from an engine that was supposed to make around 200bhp, by adding only 0.5bar to the air intake pressure. It is supposed to need at least 1 bar to do that.
Get your crayon out, draw your own conclusion.
I remember when the first lot of supercharged tvrs were coming through and the hp increases from the boost was way more than I would ever have thought possible, and yet it seems to be the case. Bizarre, yet repeatable across various installations of turbo and supercharger. I can't think that we ever tested your engine before fitting the emerald / turbo did we? That would have been interesting to have seen the changes.We just blew on it and it makes 395 bhp.
Magic
It might just be worth checking if Range Rover's quoted bhp numbers are at the flywheel, or at the wheels.
TVRs factory quoted numbers are definitely exaggerated by about 25% and are at the flywheel.
Bhp at the wheels is generally 18-20% lower than flywheel bhp.
I was very surprised when I doubled the bhp (at the flywheel) from an engine that was supposed to make around 200bhp, by adding only 0.5bar to the air intake pressure. It is supposed to need at least 1 bar to do that.
Get your crayon out, draw your own conclusion.
QBee said:
My TVR has a standard Range Rover P38 4.6 engine and standard Range Rover cam.
We just blew on it and it makes 395 bhp.
Magic
It might just be worth checking if Range Rover's quoted bhp numbers are at the flywheel, or at the wheels.
TVRs factory quoted numbers are definitely exaggerated by about 25% and are at the flywheel.
Bhp at the wheels is generally 18-20% lower than flywheel bhp.
I was very surprised when I doubled the bhp (at the flywheel) from an engine that was supposed to make around 200bhp, by adding only 0.5bar to the air intake pressure. It is supposed to need at least 1 bar to do that.
Get your crayon out, draw your own conclusion.
No car maker claims at the wheels. Always at the flywheel. We just blew on it and it makes 395 bhp.
Magic
It might just be worth checking if Range Rover's quoted bhp numbers are at the flywheel, or at the wheels.
TVRs factory quoted numbers are definitely exaggerated by about 25% and are at the flywheel.
Bhp at the wheels is generally 18-20% lower than flywheel bhp.
I was very surprised when I doubled the bhp (at the flywheel) from an engine that was supposed to make around 200bhp, by adding only 0.5bar to the air intake pressure. It is supposed to need at least 1 bar to do that.
Get your crayon out, draw your own conclusion.
Early 4.6’s where claimed to be 225hp. But in reality they where nearer to 200hp. In the USA Land Rover got taken to court over it and ended up in a recall to tweak people’s cars. Sadly I don’t know what changes they made to get the power near to the claimed figure.
Land Rovers ultimate answer was to swap to the Bosch fuel injection system with the “Thor” engines that use a different intake manifold. These are probably more powerful than the earlier engines. But LR only rated them at 214hp.
I can see no way that adding 7psi of boost will give you 395hp on this engine. I’m sure you have an awesome engine. But logical it either doesn’t make 395hp (dyno error caused) or if it does, a lot more other things are going on.
All IMO.
As for the op. I’d have thought a cammed 4.6 with the same exhaust/intake and correct tuning should be pretty close to a 4.5 assuming the heads flow a similar amount. Even in a state of tune of 100bhp/litre, which you’d be nowhere near with an RV8 you’d only be 10hp difference (10hp more with 4.6 displacement).
300bhp/ton said:
No car maker claims at the wheels. Always at the flywheel.
Early 4.6’s where claimed to be 225hp. But in reality they where nearer to 200hp. In the USA Land Rover got taken to court over it and ended up in a recall to tweak people’s cars. Sadly I don’t know what changes they made to get the power near to the claimed figure.
Land Rovers ultimate answer was to swap to the Bosch fuel injection system with the “Thor” engines that use a different intake manifold. These are probably more powerful than the earlier engines. But LR only rated them at 214hp.
I can see no way that adding 7psi of boost will give you 395hp on this engine. I’m sure you have an awesome engine. But logical it either doesn’t make 395hp (dyno error caused) or if it does, a lot more other things are going on.
All IMO.
As for the op. I’d have thought a cammed 4.6 with the same exhaust/intake and correct tuning should be pretty close to a 4.5 assuming the heads flow a similar amount. Even in a state of tune of 100bhp/litre, which you’d be nowhere near with an RV8 you’d only be 10hp difference (10hp more with 4.6 displacement).
Yes it makes 315 fly on just 2.5psi so I agree it's not a lowly 200hp engine to start with. Would have been nice to find out what it made normally aspirated before all the work.Early 4.6’s where claimed to be 225hp. But in reality they where nearer to 200hp. In the USA Land Rover got taken to court over it and ended up in a recall to tweak people’s cars. Sadly I don’t know what changes they made to get the power near to the claimed figure.
Land Rovers ultimate answer was to swap to the Bosch fuel injection system with the “Thor” engines that use a different intake manifold. These are probably more powerful than the earlier engines. But LR only rated them at 214hp.
I can see no way that adding 7psi of boost will give you 395hp on this engine. I’m sure you have an awesome engine. But logical it either doesn’t make 395hp (dyno error caused) or if it does, a lot more other things are going on.
All IMO.
As for the op. I’d have thought a cammed 4.6 with the same exhaust/intake and correct tuning should be pretty close to a 4.5 assuming the heads flow a similar amount. Even in a state of tune of 100bhp/litre, which you’d be nowhere near with an RV8 you’d only be 10hp difference (10hp more with 4.6 displacement).
spitfire4v8 said:
in fact just found this pic from when the top was off .. that's not 38mm std trumpets in there ..
We had a basic 4.6 RR engine built from an RV8 block and 4.6 range Rover crank that I had bought for £250. To this we added standard but used Range Rover heads (£50 from a Classic Range Rover fan) and a Range Rover cam (£85 new from Rimmers), then everything else came off my old 5 litre - I had broken the 5 litre engine, but still had a big box of bits. I don't actually see how a bigger inlet manifold would make any difference , as the new engine still had standard Range Rover valves on board, and the valve size is the restricting factor, Shirley?.
Sadly we never got the chance to do a before and after, Jools, even though I really wanted to and had planned to.
My plan had been to run the new engine in on the 14 CUX normally aspirated, and then bring it you for the Emerald install and a "before" BHP run, on my way to Warrington for the turbo install. Mapping to follow after the turbo was installed.
Problems with the engine build timing (nobody's fault) meant that instead I had to go straight to Warrington for the turbo without even running it in, because Eann had a long waiting list and I would have missed my turn, and we had to do the Emerald later.
You were very accommodating with my change of plan, for which I still cannot thank you enough. Your work was delayed even further because I had running in problems - a slipped little end gudgeon pin caused a second rebuild before I could complete the running in and bring it to you.
The car is now great and a total joy. On its 325bhp 2.5 psi map it drives lust like my old 5 litre did, and with the 7.5 psi map I am as quick as Phazed in his 400 bhp 5.5. Well, nearly as quick. He is still a better driver than me, and track speed is not all about bhp or even ft lbs. He drove mine around Snetterton on slicks, and seemed to enjoy himself.
Bought my 5ltr 10yrs ago. It showed 312bhp on the rollers, 26k on the clock. Lots of people said it must have had work on it. I contacted the previous owner who had it from new and he confirmed that it was how it came out of the showroom. Bearing in mind it had to have to speedo changed twice at 10,000 miles!
So some are better than others
So some are better than others
QBee said:
. I don't actually see how a bigger inlet manifold would make any difference , as the new engine still had standard Range Rover valves on board, and the valve size is the restricting factor, Shirley?.
Not really. My 4.3 made 300 PS (296 bhp) on the rollers on std sized valves. 45 mm ported manifold & ACT trumpets, carbon twin plenum, BIG Bosch AFM, ACT exhaust manifolds & decats, mapped ignition and some bits & bobs. 't Was pretty close to the 304 bhp theoretical maximum for the valve sizes and heads configuration that Puma Racing calculated, tho'... so everything else must have been pretty much spot on (on prior sessions it made 257 hp right after the rebuild, and 274 after intake & exhaust mods).
Just to add there is a world of difference between stock LR heads and stock sized valve TVR heads .... 430 (non big valve) 400 (250) for example I have witnessed some beautifully ported versions albeit with stock valves 
possibly a car like 900T's may of originally came with heads like these 
someone ordering a new 400HC for example could of spec'd these sadly no 400 or HC model I have ever seen inc mine (don't mean they didn't its TVR after all) could of saved me some money and time if it had 
to rework these mentioned TVR ported heads to further improvement would take little IMO bigger valves etc
I have witnessed some beautifully ported versions albeit with stock valves possibly a car like 900T's may of originally came with heads like these someone ordering a new 400HC for example could of spec'd these sadly no 400 or HC model I have ever seen inc mine (don't mean they didn't its TVR after all) could of saved me some money and time if it had to rework these mentioned TVR ported heads to further improvement would take little IMO bigger valves etc Edited by Sardonicus on Monday 18th February 09:37
Sardonicus said:
Just to add there is a world of difference between stock LR heads and stock sized valve TVR heads .... 430 (non big valve) 400 (250) for example I have witnessed some beautifully ported versions albeit with stock valves possibly a car like 900T's may of originally came with heads like these
Indeed (it's a 430 after all I have witnessed some beautifully ported versions albeit with stock valves possibly a car like 900T's may of originally came with heads like these ). They were quite elaborately ported from the factory. Then they were fettled some more in the course of their rebuild but for some reason the (non-TVR specific) head rebuilders back then didn't change the valves as they usually don't do that for their 'fast road' modified heads. Took them off for another fettle with intermediate large valves (bought from JED) and they also modified the valve stem seal area to make use of the modern type ones (this is a '93 car, HRC 2210 castings) and reduce friction. With a triple plenum and a TVR 885 cam (it had a Piper 285 installed at its rebuild which was showing a little wear at 43,000 miles) the engine should be good for 320-odd now.Anyway, it was just to say the valve sizes in se aren't the bottleneck at the 200-odd bhp level, far from it.
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