The V8 Owners Forum -

Spoke in depth with a few head development people about the divider and the port block and them like me could see absolutely no benefit in them and only result being detrimental to flow which is what was ultimately shown on the bench. The valve can flow far more than the port can supply and the heads would really benefit from some port work to give full potential.

I asked Real Steel about the wall thicknesses cast in the head so I would know how much one can safely cut before finding water jacket. Never got any info. The flow is pretty much the same from 0,4" to 0,6" lift which kind of shows that the port has reached the limit. I enlarged the valve throat as far as the seat allowed but further work would have required to remove the guides. The guides themselves are not streamlined at all, basically alength of tube stuck in. I think that raising the port and filling the floor for better shape would really help but also create mismatch problems with intake manifold.

I think i will take a trip to the rolling road with the modified intake ports and the Huffaker / Edelbrock. Then I will have a comparison when I fit the throttle bodies / FI

Mark

Sureley those corners can only restrict flow at the top end? I can see they could be a benefit lower down the rev range.

Hi
putting material in that corner will have 3 main effects, it will increase velocity at the bottom of the port preventing turbulent flow in that region at low engine speeds/ low valve lift thus increasing over all flow secondly it will create cause the flow to spirel to th outside of the portdirecting it around the valve and making it curve into the cylinder effectivly sending the flow straight at the spark plug and sweeping spent exhaust products away from the cylinder wall (there is a very good David Vizard article on chevy SB2 head development explaining this on Hotrod archive from about 5 years ago) finally it will reduce cylinder wall wetting down stream of the step. The other bit you chopped out will have had 2 purposes, firstly it will have caused an area of turbulant flow behind it directed at the valve stem/guide area that will have promoted fuel air mixing, secondly this will have helped low valve lift /low port velocity flow around the valve stem/guide by keeping the flow stable in this region.
Your observation that the flow is irtually the same at .4" lift as .6" lift shows just how well these heads have been developed, how many rover cams open the valve more than .5 inches? certainly bno road cams I know of lift above .55" lift. . you have probably substantially reduced lift at .4" (say 15%) to show a small (say 5%) at .6" probably with no change at .5" and how much lift does your am give? Further on a flat tappet cam of say 300 degrees open duration about 60 degrees of that will be at max lift so only 20% of the total open period will be in the region where you may have increased flow and 80% of the time the valve will be in a lift ragime where you have reduced flow.
No one puts complication in a castng core to reduce performance in a performance head, it is just not done. The fact you do not know why the metal is there is not a reason to remove it, it is a reason to find out why it is there!
Every one keeps pointing out that the old school head porters cannot get more flow out of these heads, like you they look at these ports, don't understand why these features are here and chop them out before they try anything else, they then cannot get them to flow any better. . . suprise suprise
Please remember flow above maximum valve lift on your cam is absolutly irrelevent so on anything appart from a drag race engine you do not care about flow at .6" it makes no differance you valve does not open that far. Flow above 75% max valve lift only really matters on a full chat race engine, and only then if gains are made with only very small sacrifices to lower valve lift flow.
Sorry I will putmy soap box away, but I have spent 38 years reading about engine tuning and trying to understand why some combinations work and some do not, and this is mistake number one, modifying something an expert has spent a lot of time developing just because it is counter intuitive to you.
personally I would have first tried putting a ramp in the corner ot the inlet manifold leading up to this step area to see if a smooth transition would have helped flow at higher valve lift without sacrificing low lift flow, I would then put a lead into the devider in the inlet manifold infornt of that second piece to see what difference that made to over all flow (especially low end flow).
Also bare in mind these heads were probably developed with a wet flow flow bench with die injected into the flow stream so the head developer could see what was happening as he made changes, actuallyI suspect from the changes made it would have been a pulsed flow flow bench, that is not kit that most head portes have.
As I say sorry for the rant but there is a lot more to this than just hacking out the port as big as it will go. I do not port heads beyond a quick clean up of the casting and adding manifold transition plates, I have read so much on head porting over the years that I know it is not something an amature to take on beyond the basic clean up of casting it is a job for someone with a proper modern flow wet flow bench and a fluid flow modeling software that can be used to predict what will work, what looks or feels right generally is not!
Best regards
Mike

Mike I understand what you are saying and having driven the car with the modification I still think i have done the right thing. I want top end as it is driven flat out all the time. Im pretty sure the heads were developed with mid range and bottom end in mind.
A trip to the Rolling road is in order.

Mark

I just bought my first and LAST David Vizard engine building book ever. How to port and flow test cylinder heads. I wont even bother to wipe my ass this book. Totally disappointment, waste of money. I have spoken here in Finland couple of head porter´s and some engine builders.. They are not fan of David V.. He is not respected engine builder here....

Those Merlin heads are first head´s witch has got that stupid corner and sharp fin in the floor of the port what we have seen.. Some Harley Davidson head also got this sharp fin on the floor..

Kiwicar do you mean that RS head´s are designed in professionally?
When we tested my home made RV8 head´s and Merlins in flow bench, guy laught at those heads and ask why they make up bicycle again?
And like i allways say we have seen too many excamples of building engines some computer program, flow bench vs amateur racers..
Our local V8 magazine make stroker 383 SBC engine, speding approx at least +5000£ and made only 330hp, and then they switch dyno and new cam it will made ~400hp.. Engine is designed our Famous USA car parts shop.. they get some bad reputation, because they calculate over 40hp better readings on computer than real life..
If you kiwicar are studyet near 40y engine building´s, why dont you show you secret and make firt´s +450hp Rover V8 using Merlin heads?
That could be difficult without welding those ports..

Sorry I´m difficult person, not that bad..

kokkolanpoika wrote: Sorry I´m difficult person, not that bad..

I don't think anyone noticed so you may have got away with it.

David Vizard's pretty respected in the US where he does a lot of specialised tuning work with high performance V8 engines. And he sure knew how to make A series engines perform (his book on this is still the 'bible' thirty years on).

Maybe the Fins know something about making V8 engines go harder that the Yanks (and us Aussies) don't?

Kiwicar, my cam is a Real Steel Typhoon with .480" lift and have another cam with 0,510" lift waiting to be fitted. So I would be happy to see the head flow up to 0,5" lift.

Have you actually seen the Merlin heads how these gimmicks have been carried out ? In theory I might agree with your reasoning but not after I have seen how RS did it. The corner is filled tapers back to square shape within 1/2". OK, if you need to create turbulence why do it immediately at the port face ? I would imagine that it has a negative effect, not positive. If the port is too big one can make it smaller, especially at the floor.

The fin itself is not a fin but a huge pile of material on the port floor, adjacent to the short side radius. It is not streamlined, it is not thin but it is a pile. I don´t know why it is there and when I asked RS I got no answer. Current US aftermarker heads do used similar ideas to direct flow and create swirl into the chamber. BUT, near the guide and on the roof of the port. Vizard is showing a couple of pics of this design in his book (back to it later).

As for wet flow design with these heads, dream on. When did RS first advertise these heads, 2004 or 2005 ? I have said it before and I am saying it again, if you do new heads from clean sheet why bother with factory manifolds given that the number of sold heads is quite limited. Whoever buys the heads are probably ready to invest in specific manifolds etc as well. Now you are limited with factory manifolds which dictate the location of intake manifold. By raising the intake port roughly 3/8" to 1/2" the shape would have been totally different.

These heads were designed with a budget and with the std paraphernalia in mind so I don´t think that they ever saw any wet flow testing.

I found the results from USA where Mr. Gertz had his Merlins ported and tested. These flow 200 cfm at 0.4" lift and 211 at .450" which may be considered as practical lift figures concerning the Rover cams. The flow at 0,6" is 221 cfm. Exhaust side is 160 cfm at 0,4", 164 cfm at 0,45" and 167 at 0,5".

As std the Merlins flow around 175-180 cfm mark based on several measurements both in UK, USA and here. So there is room for improvement and surprise surprise, both the fillet in the corner and the fin in the above case were removed.

What else ? Yes the book. My history involves Minis and Mr. Vizard is well known. I have quite a few of his books, both Mini and V8 related. He also ran a series of articles in Popular Hot Rodding magazine which I liked. Very well written, lots of testing done and the results based on the actual testing results. That´s why I also bought the latest book. There is a lot of technical stuff but nothing that had not already been written elsewhere.

And I was disappointed. Not perhaps because of the technical matters but the way it is written. He writes maybe 3 or 4 times how he built his first flow bench in the late 60s or early 70s. Once is enough but why so many times ? He refers to the same stuff that he wrote in Mini books (How to modify your Mini...) in 70s. It feels partly like a autobiography, not a technical book describing the latest stuff. What has his racing wins go to do with the latest in cylinder heads ?

I tend to port quite conservative, always have and always will. Be it a Mini head or Rover head. I agree with Kiwicar 100% that one needs to know what to do and what not to do.

minorv8 wrote: What else ? Yes the book. My history involves Minis and Mr. Vizard is well known. I have quite a few of his books, both Mini and V8 related. He also ran a series of articles in Popular Hot Rodding magazine which I liked. Very well written, lots of testing done and the results based on the actual testing results. That´s why I also bought the latest book. There is a lot of technical stuff but nothing that had not already been written elsewhere.

And I was disappointed. Not perhaps because of the technical matters but the way it is written. He writes maybe 3 or 4 times how he built his first flow bench in the late 60s or early 70s. Once is enough but why so many times ? He refers to the same stuff that he wrote in Mini books (How to modify your Mini...) in 70s. It feels partly like a autobiography, not a technical book describing the latest stuff. What has his racing wins go to do with the latest in cylinder heads ?

I agree..
You get same technical information A.Graham Bell book´s or even more.. I learn mutch mutch more A.Graham Bell book than D.Vizard.. I have made quick look couple of MR D.Vizard book, and i do not like those..
But that is my opinion..

And can you Robrover justify, how Triumphroverspares get near 50-60hp more using wild cat head´s, than John Eales use TA-performance head´s witch he like.. If TA-heads are ultimate heads for Rover, so there must be cross-purpose somewhere..

Also if Mr. Gertz get near 211cfm flow at Merlin´s, where is dyno results? Or is those head´s in capinet and it is chromed..
Those head´s are manufactured near 10-year´s now. So there must be some 5.2litre engine witch use those head´s, ported or not ported items. You don´t have proof..

Also if Mr. Gertz get near 211cfm flow at Merlin´s, where is dyno results?

No dyno results, just heard from him last week re. TA heads (which he also bought) and he mentioned about too many car and engine projects and too little time.

Hi
To be honnest I see very little point in adding adding comment on these heads. There are entrenched opinions here that do not seem to follow any reaon or theory on fluid flow I have understood.
However
Slagghing the primary designer of the LS series and SB2 series chevy heads as basically (paraphrase) "not knowing his stuff" just flys in the face of the evidence I have no argument for you Timo.
I am not suprised that you did not like the Vizard head porting book. He also does one on inlet tract design, I wouldn't waste your money on that one if I were you

In answer to you question
"If you kiwicar are studyet near 40y engine building´s, why dont you show you secret and make firt´s +450hp Rover V8 using Merlin heads?"

That is very simple, I looked at the rover and decided that I had no way to build a rover motor that would make more than about 350 bhp and hold together for more than 30K miles without a partial rebuild every 10k miles, even if I filled it with all chevy rotating assembly. As I could buy a 350 bhp crate chevy for a fraction of the cost of a rover making that power, and it would come with a 50K factory warrenty it was a no brainer.
Best regards
Mike

Robrover wrote:David Vizard's pretty respected in the US where he does a lot of specialised tuning work with high performance V8 engines. And he sure knew how to make A series engines perform (his book on this is still the 'bible' thirty years on).

Maybe the Fins know something about making V8 engines go harder that the Yanks (and us Aussies) don't?

Are you talking about the Fins on the inlet port floor ??

mgbv8 wrote:

Robrover wrote:David Vizard's pretty respected in the US where he does a lot of specialised tuning work with high performance V8 engines. And he sure knew how to make A series engines perform (his book on this is still the 'bible' thirty years on).

Maybe the Fins know something about making V8 engines go harder that the Yanks (and us Aussies) don't?

Are you talking about the Fins on the inlet port floor ??

I think he will mean Finland..

And Robrover, i can´t make no quarantee who´s car is faster.. All depend´s on the budget..

And kiwicar how many horses did you get and what money when you bought your chevy engine?

I have seen couple of summitracing engine dyno graph, if they promise 450hp, engine will push approx 400hp out in here.. We think those ponies will drown in Atlantic Ocean..
And one of our motoreshop build SBF engine.. They promise 340hp for 302 engine, it is emission legal engine.. 370hp engine is not anymore emission legal.. Witch i wonder why not..
And it will cost same amount of money than build approx 300-320hp rover 4.6 engine than 340hp SBF.. Only if i do porting work on my garage..