Heads - Merlin F85 VS Rover
Discussion
Which is the best road to go down with 'serious' heads for a 4.6 build?
Each has it's advantages / disadvantages the main being that the F85 is designed and built for high performance wheres a stage 3/4 rover head has to be considerably modified in order to get the kind of flow needed for 300ish BHP. However, the TVR fraternity amongst others has been using Rover ones for ages with seemingly few problems. Cost works out about the same considering I don't have an exchange pair off my 4.6. Not sure which way to go!?!
Does anyone run F85's? Any advice either way gratefully received.
Cheers
Ryan
I am running 305BHP 330ftlb on standard TVR BV heads, and not the ones with the better 500 porting either...
I believe that the better ported 500BV heads would provide further gains one mine - but this is not stage 3/4 yet, just the standard items...
What cam are you using, and how high up the rpm range does it perform..?
If you are running a TVR885 or Stealth cam, you may find the 500 heads or stage 3/4 rover heads sufficient - and a cheaper than going "aftermarket"...
Obviously if you're looking at a 404cam or similar, then it may be more advisable to look aftermarket for flow capability - but it's much more £££ as you are aware.
So I guess the question is - what's your planned set-up..?
Dom
I believe that the better ported 500BV heads would provide further gains one mine - but this is not stage 3/4 yet, just the standard items...
What cam are you using, and how high up the rpm range does it perform..?
If you are running a TVR885 or Stealth cam, you may find the 500 heads or stage 3/4 rover heads sufficient - and a cheaper than going "aftermarket"...
Obviously if you're looking at a 404cam or similar, then it may be more advisable to look aftermarket for flow capability - but it's much more £££ as you are aware.
So I guess the question is - what's your planned set-up..?
Dom
domV8 said:
What cam are you using, and how high up the rpm range does it perform..?
I'm keen on a Crower 50233 - About 6000 RPM max I'd reckon. The Engine has been fully balanced with lightened fly so it'll spin up like a blender but is only a stock 4.6 bottom end.The 50233 is built for mid and top so flow is reasonably important. I won't be thrashing it round a track regularly but won't be doris-ing it round town all day either!
domV8 said:
If you are running a TVR885 or Stealth cam, you may find the 500 heads or stage 3/4 rover heads sufficient - and a cheaper than going "aftermarket"...
Obviously if you're looking at a 404cam or similar, then it may be more advisable to look aftermarket for flow capability - but it's much more £££ as you are aware.
The thing that I liked about the merlins was the extra rocker pedestals and that they are new castings rather than reworking old rover heads. I don't want to build a 400 hp monster but if I'm spending good money I'd like to get the best available and the advantages that come with it. Last pair of 500 heads I saw were £1400 and are essentially a second hand bit of kit on the limits of what can be achieved without damaging / going to far with the porting.Obviously if you're looking at a 404cam or similar, then it may be more advisable to look aftermarket for flow capability - but it's much more £££ as you are aware.
http://www.ebay.co.uk/itm/290673911059?ssPageName=...
Ok so these are 'stage 5' but essentially the merlins offer this and more in standard trim.
I'm not slagging off the 500 Heads at all, they're very good indeed but they were never designed to be 'high performance' - unlike the merlins. And so it seems like a bit of a compromise to go with something that has to be so heavily reworked over something that has had 'performance' designed and cast into it from day 1 IYSWIM
Just get a set of V8D heads,
Even if there not special castings or super one off's there never been any complaints with them and IMO that's important
What cam did you pick?
Peter's cam went pretty well the other day at the strip, his spare one is sitting there on the self waiting for you
Even if there not special castings or super one off's there never been any complaints with them and IMO that's important
What cam did you pick?
Peter's cam went pretty well the other day at the strip, his spare one is sitting there on the self waiting for you
The problem with the Merlin heads is finding someone who has a pair on an engine and has a set of honest and impartial numbers to verify the company claims.
On paper they seem a no brainer even after the cost but I couldn't find anyone who had real and personal experience just lots of people who had none but had elected themselves as the leading authority on the product.
For that reason I didn't bite the bullet.
One thing I would say is that what they bring to the party is higher flow but I would question just how relevant this would be on a 4.6? I would hazard that at that cc there are existing Rover heads that will flow enough to extract the most from the engine.
When you get to 5 or higher then I would say the returns v cost climb quickly assuming they do what they are claimed to do.
Just my tuppence.
It would however be excellent to hear from someone who has fitted them to their own engine and has honest figures to show but when I investigated the silence was deafening. This convinced me that there was a not inconsiderable risk that they either hadn't sold any or what they had sold hadn't delivered as expected.
On paper they seem a no brainer even after the cost but I couldn't find anyone who had real and personal experience just lots of people who had none but had elected themselves as the leading authority on the product.
For that reason I didn't bite the bullet.
One thing I would say is that what they bring to the party is higher flow but I would question just how relevant this would be on a 4.6? I would hazard that at that cc there are existing Rover heads that will flow enough to extract the most from the engine.
When you get to 5 or higher then I would say the returns v cost climb quickly assuming they do what they are claimed to do.
Just my tuppence.
It would however be excellent to hear from someone who has fitted them to their own engine and has honest figures to show but when I investigated the silence was deafening. This convinced me that there was a not inconsiderable risk that they either hadn't sold any or what they had sold hadn't delivered as expected.
DonkeyApple said:
The problem with the Merlin heads is finding someone who has a pair on an engine and has a set of honest and impartial numbers to verify the company claims.
On paper they seem a no brainer even after the cost but I couldn't find anyone who had real and personal experience just lots of people who had none but had elected themselves as the leading authority on the product.
For that reason I didn't bite the bullet.
One thing I would say is that what they bring to the party is higher flow but I would question just how relevant this would be on a 4.6? I would hazard that at that cc there are existing Rover heads that will flow enough to extract the most from the engine.
When you get to 5 or higher then I would say the returns v cost climb quickly assuming they do what they are claimed to do.
Just my tuppence.
It would however be excellent to hear from someone who has fitted them to their own engine and has honest figures to show but when I investigated the silence was deafening. This convinced me that there was a not inconsiderable risk that they either hadn't sold any or what they had sold hadn't delivered as expected.
On paper they seem a no brainer even after the cost but I couldn't find anyone who had real and personal experience just lots of people who had none but had elected themselves as the leading authority on the product.
For that reason I didn't bite the bullet.
One thing I would say is that what they bring to the party is higher flow but I would question just how relevant this would be on a 4.6? I would hazard that at that cc there are existing Rover heads that will flow enough to extract the most from the engine.
When you get to 5 or higher then I would say the returns v cost climb quickly assuming they do what they are claimed to do.
Just my tuppence.
It would however be excellent to hear from someone who has fitted them to their own engine and has honest figures to show but when I investigated the silence was deafening. This convinced me that there was a not inconsiderable risk that they either hadn't sold any or what they had sold hadn't delivered as expected.
Thanks DonkeyApple an excellent answer and I expect you're quite right about the flow - if it was just a case of that then I would have been sold on the RV8's but the Merlins do have other advantages which are attractive. I certainly am no authority on the product just going by what I've read too - Maybe I'll be the first to fit some on a Chimaera!Alexdaredevilz said:
Just get a set of V8D heads,
Even if there not special castings or super one off's there never been any complaints with them and IMO that's important
Spot on Alex, you're right - I may well go for some V8D 3's just a case of weighing up all the optionsEven if there not special castings or super one off's there never been any complaints with them and IMO that's important
Alexdaredevilz said:
What cam did you pick?
Peter's cam went pretty well the other day at the strip, his spare one is sitting there on the self waiting for you
Damn, I really wanted Peter's cam but it's designed for solid lifters and I want to run hydraulic Peter's cam went pretty well the other day at the strip, his spare one is sitting there on the self waiting for you
- think I've settled on the Crower 50233 
INT/EXH - Dur @ .050” Lift: 220°/226° RR: 1.6/1.6 Gross Lift: .488”/.501” LSA: 112°
pwd95 said:
There's a chap on the V8 forum who had a set of these on his MGB 4.6 & he was making about 320bhp on a 4 barrel Webber! Read somewhere the exhaust manifold fitting was slightly different, not sure how accurate that is.
(Just off to find some linkys.....)
Excellent thanks! Good to see some hard numbers. That's pretty impressive with a Webber! (Just off to find some linkys.....)
Alexdaredevilz said:
debaron said:
Damn, I really wanted Peter's cam but it's designed for solid lifters and I want to run hydraulic - think I've settled on the Crower 50233
INT/EXH - Dur @ .050” Lift: 220°/226° RR: 1.6/1.6 Gross Lift: .488”/.501” LSA: 112°
Lady's cam - think I've settled on the Crower 50233 INT/EXH - Dur @ .050” Lift: 220°/226° RR: 1.6/1.6 Gross Lift: .488”/.501” LSA: 112°
http://www.crower.com/catalogsearch/result/?q=5023...
They must have the wrong numbers on there or maybe I'm being a d!psh!t looking at the wrong one!
This is more like it: (From the V8 Tuner site)
http://www.v8tuner.co.uk/product.php?id=591
INTAKE: Duration: 280º Lift: .488 Clearance Hot: .000
EXHAUST: Duration: 286º Lift: .501 Clearance Hot: .000
The specifications listed above are based on a rockerarm ratio of 1.60 IN 1.60 EX
LOBE SEPERATION 112º
Duration at .050" Intake: 220
Exhaust: 226
SILICONEKID340HP said:
What about the Buick heads !
I'm not using Rover/TVR heads. 1964 aluminium Buick 300, 1.75 inlets/1.5 exhausts ported and flow benched to support a potential 410 bhp, combustion chambers welded to 38cc, Buick 300 tin gaskets.
Considered em Daz, but they're reasonably rare - not to mention fifty years old! Plus they need a lot of work as well as having the chambers filled in to bring the comp ratio down. Would end up being more pricey than the Merlins I think but good shout.I'm not using Rover/TVR heads. 1964 aluminium Buick 300, 1.75 inlets/1.5 exhausts ported and flow benched to support a potential 410 bhp, combustion chambers welded to 38cc, Buick 300 tin gaskets.
Surely you have to match your heads/porting to your flow/rpm expectations..?
As I understand it - gas speeds will slow if the cross-sectional area is too large for the volume of gas going through it, with a corresponding drop in volumetric efficiency.
Therefore, you need to understand how much air the engine would be flowing at given rpms - (all other things being equal) determined by your cam - so the ports can then be specced appropriately...
Do you have printouts of the torque curve for this cam..? Or do you know at the rpms that max. torque occurs..?
Dom
As I understand it - gas speeds will slow if the cross-sectional area is too large for the volume of gas going through it, with a corresponding drop in volumetric efficiency.
Therefore, you need to understand how much air the engine would be flowing at given rpms - (all other things being equal) determined by your cam - so the ports can then be specced appropriately...
Do you have printouts of the torque curve for this cam..? Or do you know at the rpms that max. torque occurs..?
Dom
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