Rebuild time: stick 4.5 or twist 4.7.
Discussion
Jhonno said:
If you can afford it, I can't see why not..
I did get 428bhp and 375lbft torque out of a 4.5 build though..
Mine was a healthy 417bhp and 365lbft a few years back. I'm just in that position of spending a lot of money to get back to where I was, or a lot more money for an upgrade. I did get 428bhp and 375lbft torque out of a 4.5 build though..
Depends how knackered the 4.5 is. If the liners just need a hone and the pistons are fine and just need new rings then its a fair bit extra for a 4.7. £1500 or so for a set of 4.7 pistons and however much for the liners to be machined out to 4.7 bore size. If the liners and pistons have had it then a4.7 is essentially the same price as you'll be paying the same price for a new set of liners and pistons whether they're 4.5 or 4.7.
MackemPete said:
Jhonno said:
If you can afford it, I can't see why not..
I did get 428bhp and 375lbft torque out of a 4.5 build though..
Mine was a healthy 417bhp and 365lbft a few years back. I'm just in that position of spending a lot of money to get back to where I was, or a lot more money for an upgrade. I did get 428bhp and 375lbft torque out of a 4.5 build though..
MackemPete said:
Yeah I'm in that position atm. What sort of figures are they making these days?
Well that is a question to open a can of worms.What I can say is that mine was tested at Surrey Rollong Road at 402 flywheel BHP just before the rebuild and it is noticeably quicker than it was.
The rolling road figure after the rebuild on a still tight engine was 399 BHP measured at the wheels but that was on a different rolling road.
When I picked it up after mapping with a mate who was used to my car before the rebuild he commented on how it seemed to have more torque and when I booted it down a slip road his comment included the words Jesus Christ that is quick! My words were something along the lines of "fudge me".
gruffalo said:
Well that is a question to open a can of worms.
What I can say is that mine was tested at Surrey Rollong Road at 402 flywheel BHP just before the rebuild and it is noticeably quicker than it was.
The rolling road figure after the rebuild on a still tight engine was 399 BHP measured at the wheels but that was on a different rolling road.
When I picked it up after mapping with a mate who was used to my car before the rebuild he commented on how it seemed to have more torque and when I booted it down a slip road his comment included the words Jesus Christ that is quick! My words were something along the lines of "fudge me".
What spec 4.7 did you go with and who built it? Did you also upgrade the engine management. Feel free to Pm me if you'd prefer. What I can say is that mine was tested at Surrey Rollong Road at 402 flywheel BHP just before the rebuild and it is noticeably quicker than it was.
The rolling road figure after the rebuild on a still tight engine was 399 BHP measured at the wheels but that was on a different rolling road.
When I picked it up after mapping with a mate who was used to my car before the rebuild he commented on how it seemed to have more torque and when I booted it down a slip road his comment included the words Jesus Christ that is quick! My words were something along the lines of "fudge me".
The 4.7 does usually seem to give a midrange increase over a std 4.5, but not a great top end increase.
The last 4.7 I ran on my dyno made just under 390hp, and 370lb.ft
Looking back through my dyno graphs the averages for 4.7s seem to be around 400hp and 370lb.ft
The best 4.7 I've seen on a std cerb install (with further mods but a home build engine) is currently hovering around 440-450 and 400lb.ft
However a nice 4.5 to red rose spec would be around 425hp and 370lb.ft anyway.
I don't know how much the difference is between a 4.5 build to red rose spec, compared to a 4.7 from the usual builders but I do know a recent 4.7 owner who visited said his conversion totalled 11k and it made a smidge over 400hp.
If money isn't an issue there's no reason not to go for the 4.7, however why does the engine require a rebuild and can good results be had by keeping much of what you already have if still serviceable?
The last 4.7 I ran on my dyno made just under 390hp, and 370lb.ft
Looking back through my dyno graphs the averages for 4.7s seem to be around 400hp and 370lb.ft
The best 4.7 I've seen on a std cerb install (with further mods but a home build engine) is currently hovering around 440-450 and 400lb.ft
However a nice 4.5 to red rose spec would be around 425hp and 370lb.ft anyway.
I don't know how much the difference is between a 4.5 build to red rose spec, compared to a 4.7 from the usual builders but I do know a recent 4.7 owner who visited said his conversion totalled 11k and it made a smidge over 400hp.
If money isn't an issue there's no reason not to go for the 4.7, however why does the engine require a rebuild and can good results be had by keeping much of what you already have if still serviceable?
Gents
A question of philosophy
Why is it that figures are being bounded around like the differentiation of 399 and 400
BUT
No-one is willing to quote, even ballpark figures, the costs they've paid for work?
Is it a Tax Fraud issue or summat else that I cannot fathom.
I have told the world and his mother that my Cerb went from 326 bhp to 389 for £800.
That's a 20% increase for a lot less than a grand. - Unbelievable !
A question of philosophy
Why is it that figures are being bounded around like the differentiation of 399 and 400
BUT
No-one is willing to quote, even ballpark figures, the costs they've paid for work?
Is it a Tax Fraud issue or summat else that I cannot fathom.
I have told the world and his mother that my Cerb went from 326 bhp to 389 for £800.
That's a 20% increase for a lot less than a grand. - Unbelievable !
I think one of the reason that no one will post any figures regarding cost of a rebuild.
Is this is a open public forum and easily read by our dearly beloved ladies and wife's......
Is this is a open public forum and easily read by our dearly beloved ladies and wife's......
Mr Cerbera said:
Gents
A question of philosophy
Why is it that figures are being bounded around like the differentiation of 399 and 400
BUT
No-one is willing to quote, even ballpark figures, the costs they've paid for work?
Is it a Tax Fraud issue or summat else that I cannot fathom.
I have told the world and his mother that my Cerb went from 326 bhp to 389 for £800.
That's a 20% increase for a lot less than a grand. - Unbelievable !
A question of philosophy
Why is it that figures are being bounded around like the differentiation of 399 and 400
BUT
No-one is willing to quote, even ballpark figures, the costs they've paid for work?
Is it a Tax Fraud issue or summat else that I cannot fathom.
I have told the world and his mother that my Cerb went from 326 bhp to 389 for £800.
That's a 20% increase for a lot less than a grand. - Unbelievable !
I have no first hand experience of a 4.7 build but I really couldn’t bring myself to part with £10-£12k to be left with figures I could achieve from a well set up 4.5. Of course it depends what you could have the current engine rebuilt for and what the price differential is; if the difference is £2-3k then it’s maybe worth the extra, but I can’t imagine it would be.
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