How much Power.............

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Henry-b
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How much Power.............

Post by Henry-b » Sat Nov 16, 2019 9:37 pm

Can you squeeze out of an N/A 4.6?

Been pondering the idea of doing some power upgrades on my P38's 4.6.

At 125k i'm assuming her cam is toast, as its been ran on cheap 10w40 all its life, the engine itself sounds ok but needs more umph!!

Stock she has around 218hp and 407nm of torque, that was a long time ago though!!


2001 Vogue!


I'm not really wanting forced induction.


I'm assuming Cam and tappets is the first port of call?

A bit of head work Porting/polishing?


I've heard rumours of 300hp out of a N/A 4.6, is this possible?


H



minorv8
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Re: How much Power.............

Post by minorv8 » Sun Nov 17, 2019 8:18 am

Yes it is possible. But you will need a lot of cam, good heads, higher CR etc etc. All this means that you will push the hp and torque to higher revs, not perhaps ideal considering a 4X4 vehicle.

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ChrisJC
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Re: How much Power.............

Post by ChrisJC » Sun Nov 17, 2019 9:14 pm

My 4.6L engine as 4.0L pistons, ported heads, a high performance cam, Thor engine management and a mapped ECU. And 1.75" 4-2-1 exhaust manifolds and a 2.5" straight through exhaust.The rev limit has been lifted to 6000RPM.

I am hoping that lot will give me 300BHP, but until I get it on a rolling road, I don't actually know!

Chris.
--
Series IIA 4.6 V8
R/R P38 4.6 V8

sidecar
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Re: How much Power.............

Post by sidecar » Fri Nov 22, 2019 11:06 pm

I've got 300BHP out of a NA 4.6,(I've built several that make 300 BHP). Its not cheap and you need a decent ignition system none, of the standard Lucas ones work well above 5k RPM. (They just weren't built for it). Like others have said you need a good cam, inlet manifold and exhaust but you really do need a gas flowed head with big valves, the standard valves were designed for a 3.5 lump which means that the head and the valves can not flow good enough gas to allow a 4.6 to spin quick enough to make decent power. You also need to consider the gearbox, an LT77 won't last long when sat behind a 4.6 if the car is heavy.

I found that 300BHP gets boring after a while, I stuck a 100BHP NOS system on my car. The wife won't let me use it when she's in the car. :(

minorv8
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Re: How much Power.............

Post by minorv8 » Sat Nov 23, 2019 7:08 am

I am at 315 hp with a 4.6 bottom end. I have Merlin heads and a Real Steel hydraulic cam, the "biggest" they had. It is NLA though. Merlins were bought over 10 years ago when they were cheap (ish). At least if you buy new valves, springs, add machining and porting costs etc. They were not such an improvement over my previous 4.6 heads, maybe 10-15 ponies. But an increase anyway.

But yes, still rather cheap combo. I am currently assembling a 5+ litre engine with Wildcat heads. Hope I will better that 315 number :D

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Re: How much Power.............

Post by SuperV8 » Mon Nov 25, 2019 8:31 am

I'm not really wanting forced induction.
Why don't you want forced induction?
Makes a big difference on the Rover V8. When I was 'developing' my supercharged upgrade I was struggling with belt slip so was only making 2 or 3 psi and this still felt like a big difference.
You could do a simple low pressure turbo upgrade of less than 5 psi and that would be a huge torque improvement over NA tuning.

Tom.
Dax Rush 4.6 supercharged V8 MSII

Henry-b
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Re: How much Power.............

Post by Henry-b » Tue Dec 03, 2019 8:52 pm

Thanks all

I'm not against forced induction now i think about it :lol:

She has the ZF4HP24 so its a pretty stout transmission, which'll hopefully take some power :nw

I want this P38 to tow, so i'm assuming I should steer towards torque rather than Hp :mrgreen:


H

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