porting v8 heads - some observations

[coops71]

I'm in the process of doing some work to my v8 heads as recommended in Des Hammill's book. I have taken the valves out and have noticed a few things of interest. Note that this v8 has been run purely on LPG for about 10,000km and is very clean apart from in the combustion chambers and behind the inlet valves. I'd appreciate it anyone can check out the photos I have taken(link below) and give me an idea if the soft build up behind the inlet valves and in the chambers is flashlube build up(my bet) or if it is oil. The engine was using very little oil and I was running a semi synth. Also check out the casting deformity in one of the exhaust ports. I think that this along with the crud on the inlet valves may have been robbing a few hp.:o

Link:
land rover - a set on Flickr (http://www.flickr.com/photos/36609027@N06/sets/72157623157497650/)

[discowhite]

if that was purley a petrol engine ide say it way too lean, ive never seen the inside of a gas motor so the white valves may be normal???

as for porting a stock rover v8...you probably notice any differance in power, but couple it with higher comperssion ratio and then you will.

rover heads/ports are crap for HP

cheers phil

[Blknight.aus]

if its only been on LPG for 10K km that may still be the remnants of the petrol gunk coming out.

assuming that its not that

flash lube is oil so yes the carbon build up is from the motor burning oil. be it flashlube or a little more than no oil consumption past the rings its hard to tell.

the whitish stuff on the valves is lpg related but Ive not seen it quite like that before on the couple of lpg only donks Ive done its usually just a little bit around the edge of the face of the valve.

[coops71]

if that was purley a petrol engine ide say it way too lean, ive never seen the inside of a gas motor so the white valves may be normal???

as for porting a stock rover v8...you probably notice any differance in power, but couple it with higher comperssion ratio and then you will.

rover heads/ports are crap for HP

cheers phil

Not expecting any big increase in hp. Will be putting in a Crower 50229 cam. Hoping that cleaning up ports(especially exhaust) will help give some good low down and mid range. Hammill reckons on not going over 0.43" lift. The Crower cam has 0.44". Hoping this won't bind up valve springs.

[PhilipA]

Its oil of some type, maybe down the guides or maybe flashlube. I think down the guides. Maybe fit teflon guides when you have them serviced.
That cylinder looks pretty oily also.

Put quite a bit of work into the exhaust ports, as I think this is where you will pick up quite a bit, but only make the radius smooth around the bowl and raise the roof not lower the floor, and widen it around the guide. do not shorten the guide.

Inlet port work included guide off at the roof, blending into the seat, and widening towards the outer angle, exhaust bowl work and effectively 20 thou off.( 50 thou plus composite) . I also unshouded the inlet valve across to the fire ring in the chamber so the combustion chamber volume was probably unchanged. BTW the head guy could not do a 5 angle cut on the seats as the inlet valves were too small in the seat to have room.

I gained 6% across the board with work. This was dyno checked on the same dyno as previously.

It was about 30 hours with only a Dremel but 6% wasn't bad.
Regard sPhilip A

[coops71]

Its oil of some type, maybe down the guides or maybe flashlube. I think down the guides. Maybe fit teflon guides when you have them serviced.
That cylinder looks pretty oily also.

Put quite a bit of work into the exhaust ports, as I think this is where you will pick up quite a bit, but only make the radius smooth around the bowl and raise the roof not lower the floor, and widen it around the guide. do not shorten the guide.

Inlet port work included guide off at the roof, blending into the seat, and widening towards the outer angle, exhaust bowl work and effectively 20 thou off.( 50 thou plus composite) . I also unshouded the inlet valve across to the fire ring in the chamber so the combustion chamber volume was probably unchanged. BTW the head guy could not do a 5 angle cut on the seats as the inlet valves were too small in the seat to have room.

I gained 6% across the board with work. This was dyno checked on the same dyno as previously.

It was about 30 hours with only a Dremel but 6% wasn't bad.
Regard sPhilip A

So you reckon a dremel is ok for this work. Some have told me I should use an air grinder?

[Blknight.aus]

a die grinder is fine for the hheavy work but a dremel is great for the final detail and polish.

[LOVEMYRANGIE]

Use a Dremel if you aren't experienced using an air grinder as you may take out more than you expect.
Philip is pretty much on the money with the dimensions. Take out too much floor and you will suddenly find your self in a water gallery.
The head ports are not the only thing to consider. If you are going to all the trouble, make sure you
matchport both intake and exhaust manifolds otherwise it ain't worth diddly, particularly in the exhaust. The key is getting a smooth transition of gasflow across connecting parts.
RPI Engineering "RPi Engineering - Specialised Rover Engines" (http://www.v8engines.com) have a good article on matchporting. Fairly easy to do, just don't rush your measurements and mark gaskets "headside" and "manifold side" and you should be all sweet.
With the .440" lift, do the valve springs. Stock springs won't last with this particularly if their life has been spent only pushing the STD .283". Seen this too many times ans springs aren't that expensive compared to a dropped valve!
Cheers

Andrew

[coops71]

Use a Dremel if you aren't experienced using an air grinder as you may take out more than you expect.
Philip is pretty much on the money with the dimensions. Take out too much floor and you will suddenly find your self in a water gallery.
The head ports are not the only thing to consider. If you are going to all the trouble, make sure you
matchport both intake and exhaust manifolds otherwise it ain't worth diddly, particularly in the exhaust. The key is getting a smooth transition of gasflow across connecting parts.
RPI Engineering "RPi Engineering - Specialised Rover Engines" (http://www.v8engines.com) have a good article on matchporting. Fairly easy to do, just don't rush your measurements and mark gaskets "headside" and "manifold side" and you should be all sweet.
With the .440" lift, do the valve springs. Stock springs won't last with this particularly if their life has been spent only pushing the STD .283". Seen this too many times ans springs aren't that expensive compared to a dropped valve!
Cheers

Andrew

Yeah I was intending to match ports. I currently have a 500 weber and edelbrock performer manifold on the 3.5. Made a big difference to the 3.5. Once I swap it to the 3.9 it should make a fair difference. Now to get some new springs!

[loanrangie]

When i ported my heads 15 years ago i spent more time cleaning up the rough castings than actual porting, exhaust ports are very restrictive so use a gasket or the dark outline on the face to match the ports to the manifolds - both inlet and exhaust manifolds. After i did mine i fitted a bosch dizzy and a 350 holley and the difference was remarkable, heaps more revability and 70 klms extra per tank.

[Bigbjorn]

Its oil of some type, maybe down the guides or maybe flashlube. I think down the guides. Maybe fit teflon guides when you have them serviced.
Regard sPhilip A

I will reveal an old used car dealers trick to stop oil burning through worn valve guides.

Get some fuel injection hose that is a nice neat fit over the valve stem and cut to a length that allows it to concertina when the valve is fully open. This stops excessive oil being sucked into the port.

You can do this without removing the head by use of compressed air to hold the valve closed.

[400HPONGAS]

Oh dear , how right you are , Rover heads are absolute utter utter crap , as anybody into high performance egines would soon learn . If you want real performance then go Blown , its the only way you will make any serious power out of any rover head , Could allways use Oldsmobile 300 heads and a offenhauser manifold , a P76 block with a ford windsor crank with a 6 bolt girdle and still be lucky to make 350FWHP . Yes .power and Rover heads are a oxymoron !!!

[Blknight.aus]

a smooth delivery of torque across the board tho....

which given thats what you really want in an offroad engine.

the heads and engine are fit for purpose. just not much more.

when you want real power you go diesel.

[loanrangie]

The rover V8 is a great little motor, pretty tough really, i would like one in a rod .

[400HPONGAS]

Agreed , my 2 loves are landrover 4WD's and the old Holden V8's , Im just going to combine the two ! What I dont like are gutless engines that chew fuel . Dont mind gutless engines that are economical like my 200/300 TDi's or powerful engines that arent economical , like my 400-500Hp engines , just dont like gutless and uneconomical engines like the Rover V8 . (Sames as Yuckota 6 cylinder engines !!!)
Jeez that new LR4 sequential Turboed Diesel , supposed to put out 600nm of torque , thats nearly eactly the same as my 450HP petrol engines . Unreal , Im going to get a LR4 !

[Blknight.aus]

ive seen some unoffical numbers on a modified 4 pot turbo diesel pushing out well clear of 1800nm of torque. Its not a big truck engine either its physically able to fit into a deefers engine bay.

v8s sound nicer tho.

[PhilipA]

Oh dear , how right you are , Rover heads are absolute utter utter crap , as anybody into high performance egines would soon learn . If you want real performance then go Blown , its the only way you will make any serious power out of any rover head , Could allways use Oldsmobile 300 heads and a offenhauser manifold , a P76 block with a ford windsor crank with a 6 bolt girdle and still be lucky to make 350FWHP . Yes .power and Rover heads are a oxymoron !!!

A set of wildcat heads would do the trick.
Welcome to Wildcat Engineering (http://www.roverv8engine.co.uk/index2.htm)

I think Triumph Rover spares sell them.

Regards Philip A

[400HPONGAS]

Thanks for that PhillipA , didnt know this "Wildcat" mob existed , and it does look like they have produced a good head that eliminates all the terrible design errors in the standard heads . Looks like they are a Pommy mob , probably out of Wales by the given address . Wonder if there would be anychange out of $10000 AUD for a set ? !!!! , Stll why bother , a Chev/Holden motor will less than half the price and still put out far more Horsepower/Torque .Even a ALCOA special like a LSX1 or 2 or 3 would work out alot cheaper , stronger and more reliable.

[RoverP6B]

I think that the standard Rover V8 is quite adequate for its intended purpose...ie the powering of heavy 4 wheel drive vehicles, and Rover cars prior to 1987.

I run a 4.6 in my 1974 Rover, twin SU carburettors, 3 speed Tx, tons of torque just what you need for an automatic. I don't go revving beyond 4 grand so head modifications don't enter into it.

Country running sees usually less that 10 litres / 100k which is not too shabby at all.

Ron.

[400HPONGAS]

RoverP6B , I find it strange that on one hand you say that the standard V8 is fine for powering 4WD's upto 1987 (What happened in 1987 ? that made this so ? EFI was 1986 wasnt it) and on the other hand you have re-powered your 1974 vehicle with a 4.6 .I suppose the 3spd auto was one of those C4,or BW35 mods that goes on to the LT95 chopped case. Far as I know the most gutless .fuel chewing Range rover ever released was the 1985 3 spd auto (Chrysler 727A) and they were lucky to do better than 20litres per Hundred Kays , or 5 k to the litre .
Now seeing 10L per 100k , for us old fellas thats 28.25 MPG ,

What would be your average road speed and load condition be to get that ?

1985 was a weird year for Range rovers, that horrible auto ,that even just as bad LT77 manual with the twin stronmmies,and that queer/rare VM diesel version .
28,25mpg from a 4.6 V8 ,with twin SU;s and a 3 speed automatic ? ? ?

[rovercare]

Country running sees usually less that 10 litres / 100k which is not too shabby at all.

Ron.

Your calcs are out:angel:

[djam1]

I guess its true massive HP from a Rover V8 is expensive
I personally think they are a great 4x4 Motor I dont need to do burnouts or 8 second quarters I have always built 4x4 motors for low speed torque.
I do know that a Range Rover with either a Iron Chev or Holden is diminished though the handling just isnt the same.
The later alloy Chevs would be a different story though I guess

[rovercare]

I do know that a Range Rover with either a Iron Chev or Holden is diminished though the handling just isnt the same.
The later alloy Chevs would be a different story though I guess

I do closely relate this with things that smell like........

Only as much as adding duel batteries and a bullbar adds;)

I personally think the rover V8 "could" of been a great thing, add 1.5L cubic capacity MINIMUM, fit stepped liners and, just to keep it on topic, better heads:D

[RoverP6B]

Have removed my post as it was not addressing the topic of the thread,

Ron.

[400HPONGAS]

Agreed Rovercare , adding a Holden/Chev engine with alloy heads wouldnt increase the front end weight more than 50kg , however Twin batteries a Decent roo-bar perhaps a winch , spotlights , extra cooling et etc etc wii add much more and put it further out from the axle center line .As for the effect on handling ? your joking !! add in the next uprated spring rated set (usually found in the rear , LOL )
I did the big liner step up on my 4.4 block which takes it out to 5 litres , alas the horrible Rover/P76 heads still restrained any real perormance .
As for better heads , I can get the heads ( any so-called Rover big valve head) ported to a Port potential over 400HP , but that ridiculous squish/quench chamber , the dished pistons . the Tiny valves etc ,the lack of material at the pushrod chokes ,the oversize bowls ,the stepped short turn , the low lift cams , the low rocker ratio rockers , butter soft valve springs , the low Dynamic Comp ratio , all add up to finding the only was is to boost it .
The more I think about it , I come to the same conclusion that Landrover itself did , dump the old BOP/Rover engine and get something the works in this century .
Now that new LR4 with it TDV6 , now that is really something !!!!!!

[400HPONGAS]

Sorry RoverP6B , for some reason I thought we were talking about Landrovers , the 4WD ones to be exact .
"The worst fuel consumption was 27.5mpg, the best spot on 29mpg." And I calculated it to be 28.246 MPG , where did I go wrong !!!!!! Im glad your happy with your calculations . Try this Calculation . while we have gone totally off subject ,
My Stato weighs 4233lb , it has 6 litre engine (355CI) .it does 5 to 5.2 Kilometers per litre of LPG . LPG costs 60 cents a litre , Lets say tour petrol Cost $1.20 a litre. So the fuel running cost of my car is the sames as yours and it has Twice the Horsepower and Torque yours does . How about that ! (Helps when your passing a triple roadtrain etcetc)
excuse my deviance from the threads intention !!!

[RoverP6B]

Hello 400HP,

Your vehicle has far greater mass than mine, so at the end of the day it is all relative.

If my engine had more power than it currently does, it would serve no real purpose as I would not be able to legally drive any quicker than I do now.

The 4.6 does make my Rover much more enjoyable to drive compared to when it was a 3.5 litre, and the fact that it delivers better fuel consumption is just a bonus.

Ron.

[coops71]

So anyway....... I have got around tidying up my first exhaust valve. Just behind the valve seat was the biggest tidy up. Finding it hard to get down and polish at the base of the valve guide. Tried small rolls etc but to actually get in and polish is rather hard. Finished off by matching the gasket to the Hedman headers and then matching the port to the gasket. Im guessing the inlets will be a lot less time consuming. About 5 hours for one exhaust port. Im guessing about 4 for the next now that I have sussed it out. I think this will have to make some gains on power.
Im not after huge power gains. Even my old series 3 diesel had enough low down to follow chev converted toyotas up some serious hills. Have added some vids of the engine when it was in the discovery before rolling it. See if you can spot which vid has the upgraded exhaust and extractors. Should be good in the 110.


YouTube- Land Rover Discovery hill climb
YouTube- Bornholm Hill Climb

[350RRC]

I guess its true massive HP from a Rover V8 is expensive
I personally think they are a great 4x4 Motor I dont need to do burnouts or 8 second quarters I have always built 4x4 motors for low speed torque.
I do know that a Range Rover with either a Iron Chev or Holden is diminished though the handling just isnt the same.

Awwwwwwwww.............really? Have you actually driven one?

My POS has a 350 mooring block, 2" lift with HD springs with a working load leveller and it has far less body roll than a stock RRC for starters.

If you get the springs and shockers right (mine already pretty much was when I bought it) you don't really notice much difference. It handles just fine and I wouldn't hesitate buying another similar set up, or even one with an Isuzu.

And I'll say it again............. who would pull a Chev or 5l Holden out of a RRC and put in a 3.5 Rover motor as an 'upgrade'? :eek:

cheers, DL

[400HPONGAS]

You spent 5 hours on one exhaust port ? You realise Port polishing went out with the Dinosuars , 2 minutes after you start it up it will be carboned up again . Exhaust ports operate at 600PSI at 600 C temp , what is polishing anything in there going to achieve . Save your polishing for only the Combustion chamber . Fair enough grind away any obvious dags, casting abberations , but NEVER enlarge the Cross sectional area of the exhaust port other than matching all the exhaust ports to the same CSA.
Its allready "over exhausted" just use/fit the right TRi-Y extractors and align them properly . The best tool to use when Porting heads is a pair of Internal dividers .
Measure all the way through and find your maximum and minimum CSA per port , and then compare positions and sizes for all ports . Another little secret , 1 Hours work on the inlet port/valve/seat/bowl/chokes will give you 10 times the effect than messing around with exhaust ports will .
When you find out the maximum and minimum CSA's and final valve area size we can than calculate the Speed/velocity or MGV which will tell us the max Port potential in CFM which will allow us to HOG out that dreadful inlet manifold so it doesnt go Sonic or Turbulent . Velocity into MGV is far more important than Flow !!

[PhilipA]

Have you SEEN the exhaust ports on later 20 bolt heads????

It is very obvious that the cores have slipped /worn enormously and there is a giant casting ridge /flash half way down the bowl between the valve seat and roof in all ports to some degree.

I reckon that you would gain about 10% flow by just smoothing that ledge out and that is what I did as well as broadening the port around the guide and smoothing it all out.
I agree it is a waste of time to polish any port but the time spent blending the port is well spent.

BTW, In the theory books I have read the exhaust port should always be smaller than the opening in the exhaust manifold to prevent reversion of gases. ie there should be a step, not smooth transition.
Regards Philip A

[djam1]

Awwwwwwwww.............really? Have you actually driven one?

My POS has a 350 mooring block, 2" lift with HD springs with a working load leveller and it has far less body roll than a stock RRC for starters.

If you get the springs and shockers right (mine already pretty much was when I bought it) you don't really notice much difference. It handles just fine and I wouldn't hesitate buying another similar set up, or even one with an Isuzu.

And I'll say it again............. who would pull a Chev or 5l Holden out of a RRC and put in a 3.5 Rover motor as an 'upgrade'? :eek:

cheers, DL

350RRC you are right I havent owned one to be honest I am just going with the flow in terms of what I understood over the years so my statement probably is one of ignorance.
I remember back when I bought my 1973 Range Rover Classic the suspension was very finely tuned magnificent as it was it could be affected easily.
That said the other Range Rovers I owned never seemed to have the finesse that that original had but they never handled like the original either.

[coops71]

You spent 5 hours on one exhaust port ? You realise Port polishing went out with the Dinosuars , 2 minutes after you start it up it will be carboned up again . Exhaust ports operate at 600PSI at 600 C temp , what is polishing anything in there going to achieve . Save your polishing for only the Combustion chamber . Fair enough grind away any obvious dags, casting abberations , but NEVER enlarge the Cross sectional area of the exhaust port other than matching all the exhaust ports to the same CSA.
Its allready "over exhausted" just use/fit the right TRi-Y extractors and align them properly . The best tool to use when Porting heads is a pair of Internal dividers .
Measure all the way through and find your maximum and minimum CSA per port , and then compare positions and sizes for all ports . Another little secret , 1 Hours work on the inlet port/valve/seat/bowl/chokes will give you 10 times the effect than messing around with exhaust ports will .
When you find out the maximum and minimum CSA's and final valve area size we can than calculate the Speed/velocity or MGV which will tell us the max Port potential in CFM which will allow us to HOG out that dreadful inlet manifold so it doesnt go Sonic or Turbulent . Velocity into MGV is far more important than Flow !!

I spent 5 hours on and off fiddling around with making a template for matching the ports etc. A bit of reading in between. Looking back now its probably going to be about 3 hours per port. The polishing I have decided goes as far as making the port feel like glass. Doesnt take much to do with some wet and dry.

[400HPONGAS]

The Point is , you are wasting your time making any of the Port "feel like Glass" It will do nothing , Lucky its not an inlet port , any polishing to that standard of finish will absolutely ruin an inlet port . There are standards for the correct Texture to have your ports finished to. For you a finish that is only just finer than your Favourite Golfball is about right . You need to enderstand what "Laminar" , "Boundary" and "turbulent" Flow is before butchering your inlet ports . The only place such "polishing " 70 grit or better will benefit is the combustion chamber . and that dont last forever .
PS , heres a Good one for you , Try fitting Singh curves instead , and pull another.040 of the decks !!!

[350RRC]

The Point is , you are wasting your time making any of the Port "feel like Glass" It will do nothing , Lucky its not an inlet port , any polishing to that standard of finish will absolutely ruin an inlet port . There are standards for the correct Texture to have your ports finished to. For you a finish that is only just finer than your Favourite Golfball is about right . You need to enderstand what "Laminar" , "Boundary" and "turbulent" Flow is before butchering your inlet ports . The only place such "polishing " 70 grit or better will benefit is the combustion chamber . and that dont last forever .
PS , heres a Good one for you , Try fitting Singh curves instead , and pull another.040 of the decks !!!

I don't know anything about polishing ports but I can relay some info that may be of interest re: polishing and flow with sailboards and surfboards.

Traditionally surfboards were polished to a glass like finish. Sailboards and true windsurfers came along in the 80's and underwent very rapid development in every associated field including the finish.

It was found that a sailboard went faster with more control with a rougher finish (directional 320 wet & dry). Surfboards are slower and 600 worked better, giving more control. This was before the 3M skin sheets were stuck on the Yank Cup challenger in Freo in 198?

The fins on sailboards are under a huge amount of pressure and a directional 320 finish could drastically reduce cavitation on the same fin that cavitated like mad with a gloss finish.

cheers, DL

[coops71]

The Point is , you are wasting your time making any of the Port "feel like Glass" It will do nothing , Lucky its not an inlet port , any polishing to that standard of finish will absolutely ruin an inlet port . There are standards for the correct Texture to have your ports finished to. For you a finish that is only just finer than your Favourite Golfball is about right . You need to enderstand what "Laminar" , "Boundary" and "turbulent" Flow is before butchering your inlet ports . The only place such "polishing " 70 grit or better will benefit is the combustion chamber . and that dont last forever .
PS , heres a Good one for you , Try fitting Singh curves instead , and pull another.040 of the decks !!!

Yeah I know the whole 'don't polish your inlet" story. I did some reading that said that 80 grit is about the finish you need for inlets. Go back to the start of the thread and read what I initially said i.e cleaning up/following Hamill's instructions. I am not touching the port shape other than removing bits of casting etc. Most others on this site as well as Hamill mention that most gains although small come from smoothing over the roughness just below the valve seat/blending it in. Anyway - the ports tend to feel like glass even with some minor sanding with wet and dry. I have not even mentioned treatment of the inlets yet.

[up2nogood]

Interesting not port matching the exhaust. Is this absolutely the case?

[400HPONGAS]

Depends on what your definition of " Port Matching " is . Is it the alignment of the Exhaust system to the exhaust port . or that all exhaust ports are matched in CSA , which is deteremined by the bowl to choke ratio to get a MGV of between 400 -425 Ft/sec.
Does that mean you grind the exhaust flange or do you grind the Head ? What decides which thing to do ? Should there be a step in it or not ? Whats the diffrence extractors or headers or standard casties make when "Port matching ?

[coops71]

Depends on what your definition of " Port Matching " is . Is it the alignment of the Exhaust system to the exhaust port . or that all exhaust ports are matched in CSA , which is deteremined by the bowl to choke ratio to get a MGV of between 400 -425 Ft/sec.
Does that mean you grind the exhaust flange or do you grind the Head ? What decides which thing to do ? Should there be a step in it or not ? Whats the diffrence extractors or headers or standard casties make when "Port matching ?


Essentially all I am doing is removing any imperfections and ensuring the valve seat blends in nicely. I have matched the exhaust ports to the extractors but have left the ports stepping down just a half mm or so into the extractors. I am also removing any raised welds that are inside the extractors. There was some big lumps sticking maybe 5mm proud about 20mm below the valve seats in two of the four exhausts Ive done so far. These have gone now. Oh and the crud built up around the inlet valves might me due to the total lack of valve stem seals. These are 95 heads but apprently much earlier rover heads never had valve stem seals.

[Blknight.aus]

You spent 5 hours on one exhaust port ? You realise Port polishing went out with the Dinosuars , 2 minutes after you start it up it will be carboned up again . Exhaust ports operate at 600PSI at 600 C temp , what is polishing anything in there going to achieve . Save your polishing for only the Combustion chamber . Fair enough grind away any obvious dags, casting abberations , but NEVER enlarge the Cross sectional area of the exhaust port other than matching all the exhaust ports to the same CSA.
Its allready "over exhausted" just use/fit the right TRi-Y extractors and align them properly . The best tool to use when Porting heads is a pair of Internal dividers .
Measure all the way through and find your maximum and minimum CSA per port , and then compare positions and sizes for all ports . Another little secret , 1 Hours work on the inlet port/valve/seat/bowl/chokes will give you 10 times the effect than messing around with exhaust ports will .
When you find out the maximum and minimum CSA's and final valve area size we can than calculate the Speed/velocity or MGV which will tell us the max Port potential in CFM which will allow us to HOG out that dreadful inlet manifold so it doesnt go Sonic or Turbulent . Velocity into MGV is far more important than Flow !!



how highs that pressure again?
turbo diesels dont run that kind of pressure between the exhaust valve and the turbo...


the exhaust valve might open against 600 PSI but once the valve is open flow starts as pressure is just resistance to flow once the valve is open the flow starts so the pressure drops unless you have a blocked exhaust somewhere.


Given that flow and velocity are the same basic thing I'd consider them both to be important. Volume is what really counts

[400HPONGAS]

"turbo diesels dont run that kind of pressure between the exhaust valve and the turbo " Well old chap it depends where its measured , at the valve or at the port or at the manifold . Flow is meaningless with out the correct velocity . Flow and Velocity are two totally different things !!! You appear to mixing up Flow with Volume .Are you aware of Volumetric Efficiency ?

[ozscott]

Just realised this is and old thread

[kokkolanpoika]

Oh dear , how right you are , Rover heads are absolute utter utter crap , as anybody into high performance egines would soon learn . If you want real performance then go Blown , its the only way you will make any serious power out of any rover head , Could allways use Oldsmobile 300 heads and a offenhauser manifold , a P76 block with a ford windsor crank with a 6 bolt girdle and still be lucky to make 350FWHP . Yes .power and Rover heads are a oxymoron !!!

Head flow figures are just some stupid numbers, they wont mean anythink in real world.. Those head are quite poor for big engines, put for smaller they are acceptable. How many 4cylinder engine 2 valve heads fill flow near 380-400hp? Not many i say..
We have tested my home ported head on flow bench, also we tested those famous Merlin F85 heads in same bench..
My home modded heads flow 172cfm and merlins 177cfm..
So my head flow approx 355hp@ 0.55" valve lift, merlins flow approx 370hp same valve lift..

My engine valve lift is 0.5" and my heads flow approx 345hp that valve lift. And it will push over 393 flywheel horsepower.. And there is lot of capacities left.. Only limit is emission´s and drivebility.
It is possible to take over 20-30hp more for my engine.. So near 420-430hp is possible, but those last horses aren´t free..

Big valves and good flowing heads are not always the best parts..
I have seen too many poor flowing head and they will perform mutch better than good heads.

[Davo]

Just realised this is and old thread

Ah, but what a thread it is. A poor sod asks for some advice and after a helpful first page winds up with yet another highly technical discussion about how he really needs a flux capacitor because Rover V8s are so awful. Classic!

[Nick S]

Agree Davo a real classic. It amazing to watch the way these threads get out of control, reminds me of listening to some blokes at the pub. Everyone is an expert but like you said it just starts out with a simple question and then degenerates into some kind of religious argument. Good fun to watch though!

[LOVEMYRANGIE]

Half the reason I don't frequent here anymore.

[rovercare]

Half the reason I don't frequent here anymore.

To help minimize arguments? It works:p

[kokkolanpoika]

And you all continue talking off topic..

:wasntme:

[Davo]

Topic? What topic?

[PeterM]

That's half the fun!

[coops71]

It's OK everyone. I got there myself in the end. It's a beast!

[Davo]

That's good to see. I've just finished the same thing on a pair of heads and I'll do a thread on it when I have the time. And it's wasn't that hard after all . . .

[Hoges]

Must admit I find these threads illuminating in that they often expose the "secret lives" of backyard tinkerers :D More importantly such threads can also put up large signs in one's mind saying "DON'T GO THERE- save your money!"

Thanks to the rules laid down and enforced:o :BigThumb: this forum is far and away superior to others I have perused at times... sure people can get "assertive" in their technical point of view...often that's because it's from lessons hard learnt..:angel:

so thank you for the contributions: I would just "lurve" to bolt a twin screw supercharger to my 4.6, mainly for interstate trips where interminably long grades at around 600m -800m ASL across the Great Divide sap the oxygen from my poor P38's lungs, forcing me back to 3rd and even 2nd gear in the LH lane while pesky Hilux diesels and their jumped up ilk seemingly skip past in 5th... and towing trailers:eek::mad: How I miss my commodore LS1!