Merlin Heads

minorv8 · Post by **minorv8** » Sat Jan 16, 2010 3:57 pm

Crane went bankrupt, is there any info available on the net ?

kiwicar · Post by **kiwicar** » Sat Jan 16, 2010 4:12 pm

The oldsmobile version of that crane can is 238 inlet 248 exhaust on a 110 degree LSA with .536" of inlet lift, which is the same cam lift as the chevy. they don't quote it as a buick cam on their web site but I assume the buick grind id the same cam lobe, knocking off 24 thou for lash that looks like it to me. the only thing is it is listed as a hydraulic cam, but specked with at zero lash which is a little strange

That by the way is quite a long duration cam for a rover (like you hadn't noticed

) i think you will be quite safe with 11:1 cr or a little over.
Mike
PS their website says they have been bought out by another company

bigaldart · Post by **bigaldart** » Sat Jan 16, 2010 6:36 pm

Like Kiwi says the profile is a chevy one ground on a Rover/Buick blank. It works really well for top end power and Rhoades lifters tone it down for a good idle and great low end driveability, all depends on how much tappet noise is acceptable.

Alan

mgbloke · Post by **mgbloke** » Wed Jan 20, 2010 5:45 pm

Thanks guys
My plan at the moment is to have the block skimmed by 0.010 which will put the CR with composites @10.75:1 then if I use V8 tuners copper head gasket @ 0.039" compressed will put CR up to just over 11:1

Had no luck with local machine shops but Chessman were very helpful offering to do block skimming while I wait for £100. So it looks like I have a trip to Coventry soon.

Anyone want to predict what BHP/torque I can expect.
Mark

kokkolanpoika · Post by **kokkolanpoika** » Thu Jan 21, 2010 7:43 am

I just made an E-mail converstation with John Eales.. I want to break 400hp limit with my 5.2litre Rv8. But thats not a point now.
So i ask his opinion with ported Merlin heads + wildcat heads. Here is a small copy of his E-mail.

I have a pair of ported merlin heads and they flow 1 cfm less than my cnc ported big valve rover heads.

With 48 mm throttle bodies it is possible to get close to 400 bhp, but you would need a 256 or similar camshaft.

I would not recommend the Wildcat heads!!

Attached is a copy of a dyno sheet from a 5.3 litre engine that I built.

(I don´t know how to but it here? 5.3litre engine with his CNC ported heads will give 417hp, it has got 12.2Cr, 50mm crossover throttlebodies, dry sump etc..)

2nd E-mail.

I have found that the wild cat heads ports are much too big and do not give good gas speed.

The crossover inlet gives better torque and a little more bhp than the DD inlets.

Flow figures for the cnc heads is 2 % higher than the Merlin heads. At 10” test the Merlin heads flow 110 cfm

So, not sure if his trying to sell his own stuff or what? But i read also somewhere else that merlins only flow 110cfm at 10" so +-0 vs stage 4 rover heads.?

Waiting for another flowbench/dyno results still..

But what about wildcats? ports too big?

russell_ram · Post by **russell_ram** » Thu Jan 21, 2010 9:18 am

I was offering some Wildcats for flow test but wrong thread - doh !

Russ

Eliot · Post by **Eliot** » Thu Jan 21, 2010 9:38 am

I know this is a predominantly rover site - but surely once your goals are well over 300+ bhp you should be looking at alternate powerplants?

topcatcustom · Post by **topcatcustom** » Thu Jan 21, 2010 10:15 am

I know the later LS engines are ally but I'm assuming they still weigh more then the rover? Its the (only?) advantage I can see, though dont get me wrong its great to see a RV8 pushing the power limits!!!

kiwicar · Post by **kiwicar** » Thu Jan 21, 2010 10:40 am

This is getting a bit off topic, but beliefe that the rover engine is a partiulally light engine is not as significant as many think, in '64 the P5 and P6 ally blocks were very much lighter than other V8 engines, they were similar to the weight of many 4 cylinder iron block engines of the time and alot less than units like the ford Pinto. However the later stiff block castings were significantly heavier than the P6 blocks, and as versions came out like the 4 litre and 4,6 litre engine more and more metal has gone into the blockand they have got heavier.
On the other side in the US they have got better at casting thin walled blocks so they have in turn got lighter so that a 5litre SBF block is only about 60lb heavier than the 4 litre rover block. If you look at the iron block LS series (non 6 litre ones) then the block weight is more like 45-50Lb more for the iron blocks and, 30 to 40lb more for the ally ones compared to a large journal Rover. Where the Rover used to gain quite a bit over the ford and chevys was on crank and recipricating mass, however that is also reduced with the big journal Rover cranks.
An LS ally engine is not more than 30-40Lb heavier than a 4.6 rover (as far as I have been able to find out, which is not simple as there is alot of confusion on the subject of rover V8 weight) fully built up (remember the LS also has a plastic inlet manifold which is very light). bear in mind to get 400 bhp out of a rover you will need a block girdle and a long throw crank which will add even more, an LS needs a new cam, a quick port and a new chip.
Best regards
Mike

Eliot · Post by **Eliot** » Thu Jan 21, 2010 10:55 am

And to put this all into perspective - someone over on PH is selling a complete 5.3 Truck LS engine (so iron block, ally heads), complete with loom, ECU and 4L65e transmission for £1500
Combine that with HP tuners and you have a fully mappable turn-key solution.

mgbloke · Post by **mgbloke** » Thu Jan 21, 2010 11:23 am

Well in my case it doesnt really matter if merlins outflow Stg 4 rover heads. I just need them to be better than my self ported stage 3 ones.
When you weigh it up the Merlins are very good value.

Im hoping for around 310bhp which will be about 20 up on what I had.

Also swapping engines would be hugeley more expensive for me when you take into account exhaust and intake mods, gearbox, propshaft etc etc.

A friend of mine swapped his 4.6 Rover engine for a ford 302, power quoted was 345bhp but it actually made 300bhp. A head skim cam change and inlet change still only got 320bhp so now hes had to fit domed pistons to up the Cr more. The extra weight means that he has actually got less bhp per tonne than with the rover engine.

It gonna be at least another 4 weeks before I get it all back together so we will see what happens then at the rolling road. Fingers crossed.
Mark

mgbloke · Post by **mgbloke** » Tue Jan 26, 2010 12:10 pm

Now discovered that my roller rockers wont fit under the Merlin covers so I will need to get a spacer made.
Why on earth didnt they make taller rockercovers.

Spoke to real Steel who now say they have sold over 40 sets of heads.
They'r out there somewhere.

Speed 8 · Post by **Speed 8** » Tue Jan 26, 2010 2:59 pm

mgbloke wrote:Now discovered that my roller rockers wont fit under the Merlin covers so I will need to get a spacer made.
Why on earth didnt they make taller rockercovers.

Spoke to real Steel who now say they have sold over 40 sets of heads.
They'r out there somewhere.

Did you use the YT6000 set from Yella Terra? Strange they should fit under the standard Rover covers. Where exactly are you running out of clearance?

When I ordered the heads they told me the heads were developed with roller rockers in mind. Quote from original email quite a while ago...

We disigned the rocker covers to accept roller rockers & tryed to allow as much space as we could.

When I got my heads delivered about a month ago they told me they are working on development of their own roller rockers. I forgot to ask more info as I won't need them for at least 6 months.

I much like the Buick 350 setup from TA performance. I afraid there will be even more of a clearance issue with those.

mgbloke · Post by **mgbloke** » Tue Jan 26, 2010 3:57 pm

To be honest Im a bit annoyed with RS
I spoke to them today and they said that the rocker covers were designed for standard valvegear.
They said that they would have to revise the covers to accept their roller rockers when they are available.
So Far Exhaust doesnt fit, pushrods are too short and now rocker covers dont fit.
Also one of my heads has something rattling inside the waterway and according to RS its a piece of casting inside and there is nothing that can be done.
Also I would like to use studs to secure the heads but it seems they cant help with this either.
Now im thinking, is the inlet manifold going to fit?

I hope its all going to be worth it.
I wish Real Steel could come up with something positive for a change.

Darkspeed · Post by **Darkspeed** » Tue Jan 26, 2010 5:40 pm

I will get the graph sorted on the heads thread tonight with a little luck.

As a maximum the heads flowed 185CFM @ 28" on my bench

To convert to 10" its CFM B = CFM A x SQRT(PressB/PressA)

185 x SQRT(10/28 ) = 110.55 @ 10"

To be honest that figure is pretty good but it does not tell the whole story of the flow of those heads.

kokkolanpoika wrote:
....I have a pair of ported merlin heads and they flow 1 cfm less than my cnc ported big valve rover heads.

Flow figures for the cnc heads is 2 % higher than the Merlin heads. At 10” test the Merlin heads flow 110 cfm

So, not sure if his trying to sell his own stuff or what? But i read also somewhere else that merlins only flow 110cfm at 10" so +-0 vs stage 4 rover heads.?

Waiting for another flowbench/dyno results still..