rover head vs merlin. Flow tested

[kokkolanpoika]

We just made flow bench testing with my home made rover stage4 heads vs my friend merlin. Without any porting etc. Measured @ 28"

Figures: 1.7" inlet and 1.5" exchaust
Rover
Exchaust measured without tube/flange.We add only tube with our hands, made approx 10cfm more flow.
inlet exchaust
0.1" 61 63
0.2" 119 100
0.3" 155 135
0.4" 161 153
0.5" 166 141
0.6" 170 137
0.7" 171 136
Gas speed is optimal 250??? unit, dont know what?

Merlin
inlet exchaust without tube/flange
0.1" 61 60
0.2" 111 98
0.3" 160 129
0.4" 177 131
0.5" 176 131
0.6" 177 131
0.7" 177 ---
gas speed was poor over 300xxx unit,
Guy say´s that inlet port are too small, neen opened out to to approx 47x27mm, and that funny corner have to grind away gas speed almost 0 behind that corner, also shark edged have to grind away, made too mutch turbulance in flow figures vs my rover 100% stable readings..
Exchaust was quite poor vs my rover heads, He say that exchaust port might be slightly better if port roof is raised and modifield to look like STD rover port. Also exchaust port size is to small, need to open 40x27mm aproximately..

We made slightly magic with my rover exchaust port floor, we add some modeling clay in the floor, exchaust port flow figures rise approx 0.5-0.7"range 20cfm (0.7" lift 165cfm. Approx 2-3mm rising made huge difference..)

Guy say´s that if he need rover heads, he will buy set of STD rover heads, and slightly weld those exchaust and inlet port floor, they will flow lot of better..

So if my heads flow approx 166cfm with my cam witch has got maxium lift 12.7mm and made 381hp.. I don´t understand why my heads only flow approx 350hp? I always say, that flow bench figures is only some stupid numbers. We dont grind any material my heads, figures might be better if some material is grinded, but guy says that are very good indeed without flow bench porting.

Peter Burgess heads?
http://www.v8forum.co.uk/forum/viewtopi ... sc&start=0

My exchaust flow more and inlet less..

http://forum.britishv8.org/read.php?6,15718
allmost identical numbers as mine..

MEASURED 93mm BORE 96mm might made slightly better numbers?

[Darkspeed]

If you read further into the thread about heads you will see that we found exactly the same with the Merlin heads - at .450" lift they choke and we came to the same conclusion that the ports are too small for the valves and that's the flow restriction. Open up the ports and the heads will likley flow much more.

Figures we got on the graph on page 4 at 28" seem very similar to yours

Only we got there 2 years ago

Andrew

[kokkolanpoika]

Yes i know that, but someone always ask more figures, and those are made for same bench.. And "stage 4" heads figures is quite rare?

I still don´t believe merlins real horsepower potential.. Same word´s as our head porter.. They might look good with bench, but in real world like Eales say they are slightly worse with ported than his CNC head´s..

[Darkspeed]

I am open minded - The Rover heads have had thousands of hours of development thrown at them - I would not be surprised if the merlins have had 10's of hours of further development since they came out of the moulds - I think they have potential but as the money required to get the power is compared with the cost of a crate LS it just does not make an easy economic case.

Andrew

[minorv8]

Speed 8, how about the filled intake corner ? Anyone that can explain why it´s there ?

[Speed 8]

...
MEASURED 93mm BORE 96mm might made slightly better numbers?

...
Only we got there 2 years ago
...

Hi Andrew,

Nice to speak to you again. Also nice to see your chocking diagnosis confirmed. (Never doubted it )

When we took measurements of the Merlins what bore did we use? Was it 94 or 96mm?

PS. I've yet to speak a tuner who can justify/understand the little vane in the inlet port.

[Darkspeed]

Bore sleeve was at 94mm - bigger bore would make no odds as shrouding is not the problem - we took the valve out and it still made the same numbers due to the restriction being in the port.

Andrew