Feedback please on 4.7 AJP upgrade
Discussion
I'm thinking of getting my Cerby upgraded to 4.7 with the hope of reaching 500BHP. Has anybody on here had it done? I have read one thread where rich (PH'er boosted cerb) who drove somebody's a few years back, but i cant find anything else.
So far i hear it's mainly torque that improves.
All input welcome
Steve
So far i hear it's mainly torque that improves.
All input welcome
Steve
Steve, who are you looking at to do the build as to get to 500BHP you are looking at a lot more than a simple iston and liner swap. You need exhaust headers sorted, heads need attention, induction system needs mods, I would/am be putting a better crank and con rods and I think you may need to look at what cam shaft options are available.
I have seen a dyno print out of one that was making 490 BHP and 440 touquey things all at sensible revs so that is my aim, the final numbers will be what can be reached without compromising reliability.
I have seen a dyno print out of one that was making 490 BHP and 440 touquey things all at sensible revs so that is my aim, the final numbers will be what can be reached without compromising reliability.
As Gruff says the 4.7 will give a big torque boost but for outright power you need to maintain that torque for high revs which means improving the flow - mainly exhaust manifolds which are restrictive on road cerbs. The big power 4.7s tend to be racers with less tight bends in the manifolds. Flowing the heads is also worth doing and anything else that improves flow, throttle bodies etc. This is my understanding anyway.
Hey Martin, I have just spoken to Andy@APM and he said getting 500 horses will be a push. Looks like settling for the 475BHP is a good option with reliability. Anyway for now it's just been booked in with Andy for its 12k service, remap and short induction, new shocks, plus a few other bits and bobs, so looking forward to step 1 to 400ish horses 
When you get yours back, i wouldn't mind going out in it too see what it's like
Steve
When you get yours back, i wouldn't mind going out in it too see what it's like
Steve
FarmyardPants said:
As Gruff says the 4.7 will give a big torque boost but for outright power you need to maintain that torque for high revs which means improving the flow - mainly exhaust manifolds which are restrictive on road cerbs. The big power 4.7s tend to be racers with less tight bends in the manifolds. Flowing the heads is also worth doing and anything else that improves flow, throttle bodies etc. This is my understanding anyway.
Torque is the word for the 4.7 by the sounds of things. Think i'm going to save this for next year and going to enjoy the remap for the moment Skellz said:
Hey Martin, I have just spoken to Andy@APM and he said getting 500 horses will be a push. Looks like settling for the 475BHP is a good option with reliability. Anyway for now it's just been booked in with Andy for its 12k service, remap and short induction, new shocks, plus a few other bits and bobs, so looking forward to step 1 to 400ish horses
When you get yours back, i wouldn't mind going out in it too see what it's like
Steve
Not a problem Steve, hoping the new engine will be well run in by easter as I am planning to take her to Spa for a 2 day track day. Some time around then would probably be best or earlier if you want to Potter. When you get yours back, i wouldn't mind going out in it too see what it's like
Steve
andrewlloyd said:
Vee8ight said:
Is it possible to go from a 4.2 to 4.7? What would be involved?
Yes but the power would be reduced due to the inlets and also depends on the crank not being an early chocolate one ref Andy apm and about 10 grand ishEdited by andrewlloyd on Wednesday 6th November 18:58
Is it essentially a piston and liner x8 swap? Or is there more to it?
The throttle bodies are different on the 4.2, smaller and longer I believe but they can still be used if modified.
If you have an early one with the smaller journal crank then worth going billet steel, that adds £2.3k to the parts list.
I have a 4.5 and am in the process of doing this conversion and just the parts bill so far is £7.5k without any smaller items I will be looking at changing like drive shafts, bearings, gaskets, clutch, diff, fly wheel or any thing else that needs doing while she is in bits.
On top of that you have the labour, heads need a bit of work, the block needs machining, oil and water pumps should be refurbished, to optimise breathing you need to look at the exhaust headers and also the air boxes, so I would factor in for the carbon ones from ACT.
I am not trying to put you off but if you want a big power increase is is much more than just liners and pistons, I expect mine to end up at £15k or so but am aiming for big power and modern day car reliability.
If you have an early one with the smaller journal crank then worth going billet steel, that adds £2.3k to the parts list.
I have a 4.5 and am in the process of doing this conversion and just the parts bill so far is £7.5k without any smaller items I will be looking at changing like drive shafts, bearings, gaskets, clutch, diff, fly wheel or any thing else that needs doing while she is in bits.
On top of that you have the labour, heads need a bit of work, the block needs machining, oil and water pumps should be refurbished, to optimise breathing you need to look at the exhaust headers and also the air boxes, so I would factor in for the carbon ones from ACT.
I am not trying to put you off but if you want a big power increase is is much more than just liners and pistons, I expect mine to end up at £15k or so but am aiming for big power and modern day car reliability.
gruffalo said:
The throttle bodies are different on the 4.2, smaller and longer I believe but they can still be used if modified.
If you have an early one with the smaller journal crank then worth going billet steel, that adds £2.3k to the parts list.
I have a 4.5 and am in the process of doing this conversion and just the parts bill so far is £7.5k without any smaller items I will be looking at changing like drive shafts, bearings, gaskets, clutch, diff, fly wheel or any thing else that needs doing while she is in bits.
On top of that you have the labour, heads need a bit of work, the block needs machining, oil and water pumps should be refurbished, to optimise breathing you need to look at the exhaust headers and also the air boxes, so I would factor in for the carbon ones from ACT.
I am not trying to put you off but if you want a big power increase is is much more than just liners and pistons, I expect mine to end up at £15k or so but am aiming for big power and modern day car reliability.
Mmmmm think I'll stick with the 4.2, and look at nitrous or s/c, as that's a lot of £ per bhpIf you have an early one with the smaller journal crank then worth going billet steel, that adds £2.3k to the parts list.
I have a 4.5 and am in the process of doing this conversion and just the parts bill so far is £7.5k without any smaller items I will be looking at changing like drive shafts, bearings, gaskets, clutch, diff, fly wheel or any thing else that needs doing while she is in bits.
On top of that you have the labour, heads need a bit of work, the block needs machining, oil and water pumps should be refurbished, to optimise breathing you need to look at the exhaust headers and also the air boxes, so I would factor in for the carbon ones from ACT.
I am not trying to put you off but if you want a big power increase is is much more than just liners and pistons, I expect mine to end up at £15k or so but am aiming for big power and modern day car reliability.
Who am I kidding? I have enough money issues looking after 360bhp! Lol
Edited by Vee8ight on Thursday 7th November 08:21
It can be done cheaper, I am going for the ultimate if you like, I didn't need to go for the billet steel crank, or the "H" section con rods or various other bits but I did as I plan on making this engine bullet proof and only doing this once.
You can get it done for the cost of my current parts bill only, that will give you 450bhp or so i would think and a big increase in torque.
What year is your 4.2?
You can get it done for the cost of my current parts bill only, that will give you 450bhp or so i would think and a big increase in torque.
What year is your 4.2?
Would someone kindly post up their plots on the RR for a 4.7 engine. I see lots of threads and discussions but cant remember seeing a RR plot posted on PH. I'm not doubting the figures but just want to see the results. There must be a few around by now and I cant believe that everyone doing this conversion is adverse to willy waving.
Thanks for that but I know from experience that the Emerald rolling road (and they do not hind the fact to the customer) cannot measure these amounts of power so they do a frig to get the readings. It then reads very very high on any figures approaching 500bhp. I would say that this 4.7 is really producing around 440 to 450bhp and no more.
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