The V8 Owners Forum -

If the TA heads come up with the valve sizes expected then they will be comparable with Wilcats not the Merlins,

Running the typical numbers for ideal valve sizes for capacity and maximum power RPM the Merlins are still under valved.

They actually look good valve sizes for a well prepped 3.5 running 6500-7000 can only assume that the bore size may cause a shrouding issue that hurts power.

Have the Merlin flow figures been published anywhere?

Andrew

http://www.triumphroverspares.com.au/pa ... rent3id=20

only 5900AUD

do i need also rocker cover? + extra payment?

bare ones from the US only $1500 us

http://www.taperformance.com/PDF/TAPerf ... atalog.pdf

Hi
I have seen these referred to in loads of posts over the years.. . . . .But has anyone actually got their hands on a set yet, do they really exist or are they just in TA performance catalogs
Best regards
Mike

Interesting to note:
TA performance quote 270 cfm inlet, 180cfm exhaust (with porting!)
Wildcat stage 2 quote 150cfm (doesn't state which port)
Merlin 190cfm (quoted on here)

TA perf inlet dia 2.02"
TA exhaust dia 1.60"
Wildcat inlet dia 1.95"
Wildcat exhaust 1.60"
Merlin inlet dia 1.75"
Merlin exhaust dia 1.45"

Does the wildcat cfm seem like a typo? seems too low? or is the TA performance a tad optimistic!

Is there anyway to 'estimate' max hp using max CFM's or valve dia's?

Tom.

Flow figures depend on how they were tested: Wildcats are probably measured at 10" H20, whereas TA heads are most likely 28" H20 which is typical US practice. So you need to convert the figures for fair comparison. Stock Merlins are 180 cfm at 28" H20.

Tuscan heads flow :
In 181cfm with 1.693"
Ex 143cfm with 1.455"

Not really bad for full ported RV8 heads and "medium" UBV

v8man wrote: bare ones from the US only $1500 us

http://www.taperformance.com/PDF/TAPerf ... atalog.pdf

That would be for bare unfinished castings requiring machining and porting to desired spec I believe.

Kevin

No point talking about RS or TA heads been on a waiting list with RS for 3 years and TA have never even replied! At this rate these heads will never go anywhere.

No point talking about RS or TA heads been on a waiting list with RS for 3 years and TA have never even replied! At this rate these heads will never go anywhere.

I got my Merlins about 3 years ago and did not have to wait forever. Does anyone know how many pairs they have produced ? I would have thought that they have done heads during the past 3 years.

As for TA, I have received some replies but they refuse to give specific details like flow figures and valve sizes for unported head. They do quote big flow numbers but no info whether these are for ported heads. I got redirected to the land of OZ (Triumph Rover Spares) who allegedly have bought the first batch of heads.

One guy in California bought Merlins, had them flow tested and then ported and again flow tested. They improved quite a bit. The same guy has also ordered a pair of TA heads. Naturally the delivery has been rescheduled due to machining problems or whatever.

I was speaking to John Eales this week about sumps and he asked what my engine spec was. I told him I was using merlin heads and how successful they were.
He recons that they are really bad and that he has a few pairs sat in the corner that he cant get rid of because his stage 4 rover heads make a lot more power. Might be just sales talk?

Mark

NASD90, maybe it´s worth calling Mr. Eales and help him get rid of one pair. I would not be surprised if he refuses to sell them because a) they are so bad that he simply can´t sell bad stuff and b) his heads are so much better that you need to have them.

Well, I can only speak for myself. Merlins made more power on my engine than my ported Rover 4,6 heads. Not as much as I had expected though. Yes, I would buy TA heads today since they appear to have much more potential but like already mentioned, nobody knows when they are really available.

You always compare merlin head´s to stage 3 speck´s..
Merlin heads are close to stage 4 speck´s, same valve size (inlet 1mm bigger with merlin) flow potential almost identical.
I have seen/hear over 400hp readings with stage 4 heads, Eales 5.2litre 417hp and V8 developments 5.5litre race engine +432hp.. (+my home made street 5.2litre 381hp)

And merlin head´s are sold i think at least 30pair´s? 4 dyno results, minorV8 307hp? RPI injection 4.6litre engine 307hp, realsteel 5.0litre, similar like mgbloke engine and made +330hp, + mgbloke 4.8litre over +330hp
In my mind some dosen´t match with those dyno readings..

And why don´t Real Steel manufacture those heads in say 3-6month? if they are so popular that someone have to wait over 3years.. if they are real performer and if i was a Real Steel owner, i will make at least 50-pair 4sale.

Speak to V8 tuner, he estimate that next set of merlin´s are manufactured March/April, and price is higher now..

I have also hear in this forum that 4.5litre stage 4 engine will made +336hp..

I belive quite bit with John Eales word

Hi
I find 417 bhp out of a set of stage 4 ported heads a little optomistic, unless they are TVR bhp that is . . . the flow figures I have seen put stage 4 rover head flow figures around 180 cu ft/min http://www.leylandp76.com/technical/tech-headflow.html
Chevy Vortec heads, stage 1 ported are reconed to be good for around 410 to 420 BHP and flow about 230 Cuft. On a good duel plane manifold, tubular headers and about 225 degrees of timing at .05" of lift. That puts a 5.7 chevy as road drivable but not fun in traffic.
The head flow figures just do not stack up, you may get 417 if it is a seriously lumpy mechanical cam, port fuel injection and can live with a 1500 rev wide powerband, but a not anything that would could be driven on the road. Sorry but I think someone's dyno is more than a little hopefull.
Best regards
Mike

mgbloke wrote:I was speaking to John Eales this week about sumps and he asked what my engine spec was. I told him I was using merlin heads and how successful they were.
He recons that they are really bad and that he has a few pairs sat in the corner that he cant get rid of because his stage 4 rover heads make a lot more power. Might be just sales talk?

Mark

I have spoken to John about Merlin heads and have seen the comparative dyno figs. He does have several knocking about his workshop, propping doors open etc