Rover 3.9 heads, how much metal for porting?
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Rover 3.9 heads, how much metal for porting?
Doing a set of rover 3.9 heads for a 5.0L stroker engine that I'm building, shooting for 450hp from it for a road racer.
I had some junk 3.5 heads to fiddle with & ended up finding water on them, haven't got any junk 3.9 heads to experiment on tho, so I'm going slow on the good castings.
I've fitted oversize interlocking seats 1.84" intake valves & 1.4" exhausts.
Was expecting to have trouble getting the exhausts up to scratch with the little 1.4" valves, but got them sorted no probs.
Where I'm at now is I've got the intakes moving 225cfm at high lift, but I've got some turbulence/separation around .450" lift, it recovers but still doesn't sound right - if I can fix it I'm pretty sure it'll pick up enough that I'll be happy with the port, time on the bench with the velocity probe etc is pointing at needing to lay back the turn some more.
Problem is when playing with the 3.5 heads I had the same issue, fixed it but hit water on the corner of the short turn.
I'd really rather not junk this head, so if anyone knows if the 3.9 heads have more metal in the short turn area than the 3.5's that'd be real handy info!
I suspect they do, the ports are quite different although they look similar initially.
Can't find much info on the net on these heads, just some UK shops touting how good their heads are - but they all have smaller intake valves & larger exhausts & no flow figures, so it's a fair bet they haven't been taken as far as these.
Flow as it sits:
intake:
.1 - 59.7
.2 - 125
.3 - 175.5
.4 - 204.5
.45 - 215
.5 - 213
.55 - 212
.6 - 215
.65 - 218.5
.7 - 221
.75 - 223
.8 - 225
exhaust
.1 - 47
.2 - 86.5
.3 - 123
.4 - 148
.5 - 159
.55 - 160.5
.6 - 161.5
.65 - 162
.7 - 162
.75 - 163
.8 - 163
Pics so far:
exhaust port:
I had some junk 3.5 heads to fiddle with & ended up finding water on them, haven't got any junk 3.9 heads to experiment on tho, so I'm going slow on the good castings.
I've fitted oversize interlocking seats 1.84" intake valves & 1.4" exhausts.
Was expecting to have trouble getting the exhausts up to scratch with the little 1.4" valves, but got them sorted no probs.
Where I'm at now is I've got the intakes moving 225cfm at high lift, but I've got some turbulence/separation around .450" lift, it recovers but still doesn't sound right - if I can fix it I'm pretty sure it'll pick up enough that I'll be happy with the port, time on the bench with the velocity probe etc is pointing at needing to lay back the turn some more.
Problem is when playing with the 3.5 heads I had the same issue, fixed it but hit water on the corner of the short turn.
I'd really rather not junk this head, so if anyone knows if the 3.9 heads have more metal in the short turn area than the 3.5's that'd be real handy info!
I suspect they do, the ports are quite different although they look similar initially.
Can't find much info on the net on these heads, just some UK shops touting how good their heads are - but they all have smaller intake valves & larger exhausts & no flow figures, so it's a fair bet they haven't been taken as far as these.
Flow as it sits:
intake:
.1 - 59.7
.2 - 125
.3 - 175.5
.4 - 204.5
.45 - 215
.5 - 213
.55 - 212
.6 - 215
.65 - 218.5
.7 - 221
.75 - 223
.8 - 225
exhaust
.1 - 47
.2 - 86.5
.3 - 123
.4 - 148
.5 - 159
.55 - 160.5
.6 - 161.5
.65 - 162
.7 - 162
.75 - 163
.8 - 163
Pics so far:
exhaust port:
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Re: Rover 3.9 heads, how much metal for porting?
If you could pick up 10 more cfm at around .500" lift or so that 450 HP would come a bunch faster!
Two things to try.
1) since you have not gone thru the roof yet leave the short turn left to right wise on the common wall side high and a rise the roof , less D and more U on that common wall to floor section. In fact you might try while doing that adding some clay to the floor on that side to make the drop off into the bowl more gentle as in laying back the floor but in reverse.
To get this right many times that added floor height needs to carried right on back to the flange so the corespondent added roof height will make for a Trapazoide shape to the runner on that side .
Next up would be to kill or greatly reduce that issue at .450" lift, take a pencile or pen , hold it at a 30 to 45 degree angle and set its flat end down on the floor about .250" away from the common wall and slid it in deeper into the runner starting at the flange.
At some point most times about 1 inch in you hear the bench smooth out and the pressure reading drop lower, at this point you know that you can help get rid of some or all of the issue by making a tear drop shaped affair out of epoxy and gluing it down with its fat end towards the short turn .
The main thing is to have as little turbulence as possible at the valve lift point where the piston has hit its greatest velocity down the bore and is demanding the best air flow it can get!
Also not exceeding 350 FPS anywhere in the port or bowl will be just as important as the sheer air flow numbers!
You've got one saving grace here in that the head is not iron, so if you need to blow thru the floor and weld it up so as to not top 350 FPS I would do so.
Nice work by the way, but I would ditch that polish in the intake ports for the sake of fuel management before calling it a day.
I work my ports so that a polish leaves me 1/32" away from the size I am looking for and then I go back in with a well lubed fine cut iron Burr to end up with the final texture I want.
I would not fret over the Exh numbers as they are fine, in fact you could likely run a single patter Cam and gain some cylinder pressure.
Two things to try.
1) since you have not gone thru the roof yet leave the short turn left to right wise on the common wall side high and a rise the roof , less D and more U on that common wall to floor section. In fact you might try while doing that adding some clay to the floor on that side to make the drop off into the bowl more gentle as in laying back the floor but in reverse.
To get this right many times that added floor height needs to carried right on back to the flange so the corespondent added roof height will make for a Trapazoide shape to the runner on that side .
Next up would be to kill or greatly reduce that issue at .450" lift, take a pencile or pen , hold it at a 30 to 45 degree angle and set its flat end down on the floor about .250" away from the common wall and slid it in deeper into the runner starting at the flange.
At some point most times about 1 inch in you hear the bench smooth out and the pressure reading drop lower, at this point you know that you can help get rid of some or all of the issue by making a tear drop shaped affair out of epoxy and gluing it down with its fat end towards the short turn .
The main thing is to have as little turbulence as possible at the valve lift point where the piston has hit its greatest velocity down the bore and is demanding the best air flow it can get!
Also not exceeding 350 FPS anywhere in the port or bowl will be just as important as the sheer air flow numbers!
You've got one saving grace here in that the head is not iron, so if you need to blow thru the floor and weld it up so as to not top 350 FPS I would do so.
Nice work by the way, but I would ditch that polish in the intake ports for the sake of fuel management before calling it a day.
I work my ports so that a polish leaves me 1/32" away from the size I am looking for and then I go back in with a well lubed fine cut iron Burr to end up with the final texture I want.
I would not fret over the Exh numbers as they are fine, in fact you could likely run a single patter Cam and gain some cylinder pressure.
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
Re: Rover 3.9 heads, how much metal for porting?
Maybe a Chicom sonic tester?
Jack Vines
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Re: Rover 3.9 heads, how much metal for porting?
> Doing a set of rover 3.9 heads
Those appear to be post 1994 heads as used on the Rover 4.0L/4.6L. They were also used on later 3.9L and 4.2L Rovers but most refer to them as 4.0L/4.6L Rover heads. You might find some more info if you search on 4.0L/4.6L Rover heads. As you probably already know, the later heads have 10 bolt holes (versus 14), smaller 28cc chambers (versus 36cc), intake ports notched for injectors and larger exhaust ports.
> some UK shops touting how good their heads are - but they all have smaller intake valves & larger exhausts & no flow figures, so it's a fair bet they haven't been taken as far as these.
Here are flow numbers for CNC ported Rover heads from John Eales (JE Developments) in England. These have 1.71" intake and 1.5" diameter exhaust valves and were tested at a 28" pressure drop with a 4" bore adapter:
<pre>
As delivered
Lift Intake Exhaust
inch 1.71" 1.5"
0.050 32.5 24.6
0.100 59.0 48.6
0.150 86.9 69.6
0.200 114.4 86.1
0.250 139.5 100.6
0.300 158.8 113.8
0.350 173.6 125.2
0.400 181.5 132.5
0.450 184.8 137.5
0.500 186.8 140.3
0.550 188.2 142.5
0.600 189.7 144.4
0.650 190.6 145.3
Additional work by Classic Jaguar in Austin, TX
Lift Intake Exhaust
inch 1.71" 1.5"
0.050 29.9 23.7
0.100 57.9 49.9
0.150 86.3 76.7
0.200 111.6 97.1
0.250 137.1 113.8
0.300 155.3 129.6
0.350 169.5 139.1
0.400 181.5 145.5
0.450 185.0 149.5
0.500 188.8 152.5
0.550 190.6 154.1
0.600 192.3 155.2
0.650 192.3 156.3
0.700 192.7 156.8
If you can get your hands on a pair, the 1964 Buick 300 aluminum heads are a direct bolt on and are easier to pull 200+ CFM from:
1964 Buick 300 aluminum heads
1.775" 1.5"
0.100 66 47
0.150 99 82
0.200 129 104
0.250 155 119
0.300 174 130
0.350 187 139
0.400 191 146
0.450 194 150
0.500 196 152
0.550 200 153
0.600 200 153
</pre>
Those Buick 300 heads were fitted with larger seats and Ferrea 6000 series Buick V6 Stage 1 stainless steel valves (1.775" intake and 1.5" exhaust). Intakes have a 10 degree "Super Flo" head shape while the exhausts are 29 degree tulips. The heads were hand ported by Jon Carls of JDC Engineering in Minonk, IL. I supplied Jon with a corroded Buick 300 head which he used to determine the casting material thickness limits but this was a street porting, not an all out effort. Cost (in the United States) for the ported Buick 300 heads was (much) less than half the JE ported Rover heads from England.
> 5.0L stroker engine that I'm building, shooting for 450hp from it for a road racer.
With the ported JE heads mentioned above and a Harcourt single plane intake manifold, a 4.9L Rover (offset ground 4.6L Rover crankshaft) made 391 HP @ 6300 RPM and 357 ft-lbs @ 5000 RPM. That was a street build with hydraulic roller cam. The owner has since installed side draft Webers. I modeled the engine in Dynomation and it predicts 395 HP at around 6000 RPM. If I swap in your flow numbers and valve sizes above and make some guesses on minimum cross-sectional area and port entry size, the prediction is for another 35 HP with no other changes. A bit more cam/compression/carb should put you in the 450 HP range.
> I've fitted oversize interlocking seats 1.84" intake valves & 1.4" exhausts.
Those are the best flowing ported OEM Rover heads I've seen. Is there any concern with shrouding with the larger intake valves? I recently had a TA Performance Rover heads on the flow bench and they have 1.94"/1.6" valves but the valves have been relocated to the bore centerline to minimize shrouding.
I've seen some pictures of a set of welded and re-worked Rover heads that David Vizard did that looked quite good but I never saw any flow bench info on them:
I've got a set of ported Rover heads that came off a 5.0L Rover autocross engine that I purchased a while back. I should have them on a flow bench next week. They are 3.9L Rover castings but are the early 14 bolt version and are fitted 1.782" intake and 1.450" exhaust valves with an overall length of 5.030" so I suspect they are Ferrea F5012 and F5014 small block Ford valves. I need to take some pictures of the ports but the intake ports measure 1.11" wide by 1.91" tall (2.12 square inches). The exhaust ports are smaller than yours at 0.865" wide by 1.525" tall but that might be okay as they should match the Rimmers stainless steel tri-y headers that are currently on my Triumph TR8. Minimum port cross-sectional areas (MCSA) are approximately 1.90 square inches intake and 1.23 square inches exhaust. The exhaust port exits are rounded on top and flat on bottom and fit my header gaskets with only minor trimming to match the port roof so there's a good chance they will match the small tube tri-ys.
The chambers have been welded up to provide a quench pad but oddly the pistons are 0.050" down the hole at TDC so they weren't providing any sort quench effect.
The plan is to run those heads on a temporary engine (either a 4.2L or 4.6L Rover) along with an Edelbrock Performer Rover dual plane intake manifold while the Rover 5.0L gets rebuilt with the TA Performance Rover heads. The Extrude Hone process left the plenum very smooth:
I need to decide if I want to try to rough up the plenum and ports or leave as is. Ports are substantially larger than an unported Performer Rover:
Dan Jones
Those appear to be post 1994 heads as used on the Rover 4.0L/4.6L. They were also used on later 3.9L and 4.2L Rovers but most refer to them as 4.0L/4.6L Rover heads. You might find some more info if you search on 4.0L/4.6L Rover heads. As you probably already know, the later heads have 10 bolt holes (versus 14), smaller 28cc chambers (versus 36cc), intake ports notched for injectors and larger exhaust ports.
> some UK shops touting how good their heads are - but they all have smaller intake valves & larger exhausts & no flow figures, so it's a fair bet they haven't been taken as far as these.
Here are flow numbers for CNC ported Rover heads from John Eales (JE Developments) in England. These have 1.71" intake and 1.5" diameter exhaust valves and were tested at a 28" pressure drop with a 4" bore adapter:
<pre>
As delivered
Lift Intake Exhaust
inch 1.71" 1.5"
0.050 32.5 24.6
0.100 59.0 48.6
0.150 86.9 69.6
0.200 114.4 86.1
0.250 139.5 100.6
0.300 158.8 113.8
0.350 173.6 125.2
0.400 181.5 132.5
0.450 184.8 137.5
0.500 186.8 140.3
0.550 188.2 142.5
0.600 189.7 144.4
0.650 190.6 145.3
Additional work by Classic Jaguar in Austin, TX
Lift Intake Exhaust
inch 1.71" 1.5"
0.050 29.9 23.7
0.100 57.9 49.9
0.150 86.3 76.7
0.200 111.6 97.1
0.250 137.1 113.8
0.300 155.3 129.6
0.350 169.5 139.1
0.400 181.5 145.5
0.450 185.0 149.5
0.500 188.8 152.5
0.550 190.6 154.1
0.600 192.3 155.2
0.650 192.3 156.3
0.700 192.7 156.8
If you can get your hands on a pair, the 1964 Buick 300 aluminum heads are a direct bolt on and are easier to pull 200+ CFM from:
1964 Buick 300 aluminum heads
1.775" 1.5"
0.100 66 47
0.150 99 82
0.200 129 104
0.250 155 119
0.300 174 130
0.350 187 139
0.400 191 146
0.450 194 150
0.500 196 152
0.550 200 153
0.600 200 153
</pre>
Those Buick 300 heads were fitted with larger seats and Ferrea 6000 series Buick V6 Stage 1 stainless steel valves (1.775" intake and 1.5" exhaust). Intakes have a 10 degree "Super Flo" head shape while the exhausts are 29 degree tulips. The heads were hand ported by Jon Carls of JDC Engineering in Minonk, IL. I supplied Jon with a corroded Buick 300 head which he used to determine the casting material thickness limits but this was a street porting, not an all out effort. Cost (in the United States) for the ported Buick 300 heads was (much) less than half the JE ported Rover heads from England.
> 5.0L stroker engine that I'm building, shooting for 450hp from it for a road racer.
With the ported JE heads mentioned above and a Harcourt single plane intake manifold, a 4.9L Rover (offset ground 4.6L Rover crankshaft) made 391 HP @ 6300 RPM and 357 ft-lbs @ 5000 RPM. That was a street build with hydraulic roller cam. The owner has since installed side draft Webers. I modeled the engine in Dynomation and it predicts 395 HP at around 6000 RPM. If I swap in your flow numbers and valve sizes above and make some guesses on minimum cross-sectional area and port entry size, the prediction is for another 35 HP with no other changes. A bit more cam/compression/carb should put you in the 450 HP range.
> I've fitted oversize interlocking seats 1.84" intake valves & 1.4" exhausts.
Those are the best flowing ported OEM Rover heads I've seen. Is there any concern with shrouding with the larger intake valves? I recently had a TA Performance Rover heads on the flow bench and they have 1.94"/1.6" valves but the valves have been relocated to the bore centerline to minimize shrouding.
I've seen some pictures of a set of welded and re-worked Rover heads that David Vizard did that looked quite good but I never saw any flow bench info on them:
I've got a set of ported Rover heads that came off a 5.0L Rover autocross engine that I purchased a while back. I should have them on a flow bench next week. They are 3.9L Rover castings but are the early 14 bolt version and are fitted 1.782" intake and 1.450" exhaust valves with an overall length of 5.030" so I suspect they are Ferrea F5012 and F5014 small block Ford valves. I need to take some pictures of the ports but the intake ports measure 1.11" wide by 1.91" tall (2.12 square inches). The exhaust ports are smaller than yours at 0.865" wide by 1.525" tall but that might be okay as they should match the Rimmers stainless steel tri-y headers that are currently on my Triumph TR8. Minimum port cross-sectional areas (MCSA) are approximately 1.90 square inches intake and 1.23 square inches exhaust. The exhaust port exits are rounded on top and flat on bottom and fit my header gaskets with only minor trimming to match the port roof so there's a good chance they will match the small tube tri-ys.
The chambers have been welded up to provide a quench pad but oddly the pistons are 0.050" down the hole at TDC so they weren't providing any sort quench effect.
The plan is to run those heads on a temporary engine (either a 4.2L or 4.6L Rover) along with an Edelbrock Performer Rover dual plane intake manifold while the Rover 5.0L gets rebuilt with the TA Performance Rover heads. The Extrude Hone process left the plenum very smooth:
I need to decide if I want to try to rough up the plenum and ports or leave as is. Ports are substantially larger than an unported Performer Rover:
Dan Jones
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Re: Rover 3.9 heads, how much metal for porting?
In the early to mid 80's California's Huffaker Engineering campaigned a Triumph TR8 with factory support - - reports were they experienced difficulty exceeding 300hp from the stock 3500 cc's, and I distinctly recall Joe Huffaker saying they felt the combustion chamber shape was at fault - - but couldn't be changed due to Class regulations
So, interesting to see your photos of the Rover castings modified for Autocross - - and suspect they'd be further improved if shaped similarly to the Nissan/Datsun L4 heads created by Tony Knight of Adelaide and featured here a couple of weeks ago
I also recall Nissan 260Z turbo valves were a prudent oversize drop in substitute when paired with bronze Porsche guides - -
This site also hosts several other threads on the Buick Pontiac Olds Rover engine's history and mods, including Leyland Australia's short lived 4400cc version
So, interesting to see your photos of the Rover castings modified for Autocross - - and suspect they'd be further improved if shaped similarly to the Nissan/Datsun L4 heads created by Tony Knight of Adelaide and featured here a couple of weeks ago
I also recall Nissan 260Z turbo valves were a prudent oversize drop in substitute when paired with bronze Porsche guides - -
This site also hosts several other threads on the Buick Pontiac Olds Rover engine's history and mods, including Leyland Australia's short lived 4400cc version
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Re: Rover 3.9 heads, how much metal for porting?
Another thing to keep in mind is that under SCCA rules in the Production car categories, they have to use stock valve sizes and intake manifold. In "full prep" trim like they were in C-Production at the time, they could do as much porting as they could, but the clause "cannot add any material" negates being able to weld up the chambers and the like.Leftcoaster wrote:In the early to mid 80's California's Huffaker Engineering campaigned a Triumph TR8 with factory support - - reports were they experienced difficulty exceeding 300hp from the stock 3500 cc's, and I distinctly recall Joe Huffaker saying they felt the combustion chamber shape was at fault - - but couldn't be changed due to Class regulations
So, interesting to see your photos of the Rover castings modified for Autocross - - and suspect they'd be further improved if shaped similarly to the Nissan/Datsun L4 heads created by Tony Knight of Adelaide and featured here a couple of weeks ago
I suspect even under those rules, Tony would be able to get a bunch more than those back in the day.
Great work as always, Tony. Your stuff always looks great and the numbers are always fantastic.
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Re: Rover 3.9 heads, how much metal for porting?
good info guys, cheers.
I reworked the port a little, avoided the spot in the turn where I reckon it's thin, but laid back the rest a bit more & got into the bottom cuts of the valve job on the turn a bit more as well, also raised the roof & blew out the bowl & window a bit more.
But hit water in the bowl, welded it up this morning, it's all good, I'll finish dressing the weld on Monday & flow it, fingers crossed coz I'm running out of metal to play with!
I reworked the port a little, avoided the spot in the turn where I reckon it's thin, but laid back the rest a bit more & got into the bottom cuts of the valve job on the turn a bit more as well, also raised the roof & blew out the bowl & window a bit more.
But hit water in the bowl, welded it up this morning, it's all good, I'll finish dressing the weld on Monday & flow it, fingers crossed coz I'm running out of metal to play with!
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Re: Rover 3.9 heads, how much metal for porting?
Tony, given your penchant for radical cylinder head mods, have you considered plotting wall thicknesses with an ultrasonic guage?
After researching offerings on this and other sites, six months ago for US$275 I purchased a Mitec150 with 12mm od probe from a presumably China based eBay vendor - - unit arrived promptly in perfect shape, as did a similar but 10mm od probe ordered later - - unfortunately can't comment on their accuracy as moving shop comes first
Perhaps other, recent thickness guage purchasers would care to comment?
Incidentally, vendors seem to advertise the id of the metal probe surrounding the ultrasonic wave generator/receiver, not the od of the metal probe itself - - obviously that's of no consequence if measuring flat or gently curved objects, but ports demand the smaller diameters and even then the probe "end" must be rounded off to approach the port id, petroleum jelly being used to bridge any "air gap" for repeatable readings
Your handiwork produces works of art which, even for a worthy cause, don't deserve to be hidden from view - -
After researching offerings on this and other sites, six months ago for US$275 I purchased a Mitec150 with 12mm od probe from a presumably China based eBay vendor - - unit arrived promptly in perfect shape, as did a similar but 10mm od probe ordered later - - unfortunately can't comment on their accuracy as moving shop comes first
Perhaps other, recent thickness guage purchasers would care to comment?
Incidentally, vendors seem to advertise the id of the metal probe surrounding the ultrasonic wave generator/receiver, not the od of the metal probe itself - - obviously that's of no consequence if measuring flat or gently curved objects, but ports demand the smaller diameters and even then the probe "end" must be rounded off to approach the port id, petroleum jelly being used to bridge any "air gap" for repeatable readings
Your handiwork produces works of art which, even for a worthy cause, don't deserve to be hidden from view - -
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Re: Rover 3.9 heads, how much metal for porting?
> they could do as much porting as they could, but the clause "cannot add any material" negates being able to weld up the chambers
Given that the Huffaker single plane intake manifold is a perfect match for the GM 215 race heads (which use the larger Buick 300 ports but have the smaller Buick 215/Rover combustion chambers), I've often wondered if Huffaker didn't have some engines running the GM race heads:
I didn't have any shots showing the Rover 3.9L ports handy so I took a couple pictures today. Notice how narrow the exhaust port is. It will be interesting to see how well it flows through that tiny port.
> So, interesting to see your photos of the Rover castings modified for Autocross - - and suspect they'd be further improved if shaped similarly to the Nissan/Datsun L4 heads created by Tony Knight of Adelaide and featured here a couple of weeks ago
They might and I'm sure they would benefit from some additional exhaust side porting but these are only going to be used on the temporary/back up engine so will be freshened and run as is. The primary engine will get a ported set of the TA Performance Rover heads. They also have a quench style combustion chamber and flow roughly double what an unported OEM Rover head does:
They received a bowl porting and chamber polishing. On the intake side, only a minor amount of material was removed to match the ports to the Willpower single plane intake manifold (drilled for EFI):
The exhaust ports received the bulk of the porting and were enlarged to fit larger 1 5/8" primary tri-y headers (Kirk Racing design as sold by Woody Cooper of the The Wedge Shop and Ted Schumacher at TSI):
Heads were ported by Bob Stiegemeier of Stiegemeier Porting Service (http://stiegemeier.com/) in St. Charles, Missouri USA and were tested at a 28" pressure drop on a SuperFlow 600 flow bench. Intake ports were flowed with a clayed radius around the intake port. No pipe was used on the exhaust. Flow is in cubic feet per minute (CFM) and lift is in inches. Intake valve diameter is 1.94" and exhaust diameter is 1.6". Note that the heads were purchased assembled and Bob worked around the existing valve job. For my application, only minor work was required on the intake side so most of the effort was concentrated on the exhaust. Heads were flowed unported, ported and ported with a 30 degree back cut on the intake valves. Columns are as follow:
1 = out of box intake ports
2 = ported intake, no back cut on intake valves
3 = ported intake, 30 degree back cut on intake valves
4 = out-of-box exhaust ports, no pipe stub
5 = ported exhaust, no back cut on exhaust valves, no pipe stub
<pre>
</pre>
Bob noted the flow for the ported intake with back-cut valves was for the first one he did. He got closer to 260 CFM peak on subsequent valves. He believes he can do better if starting with heads without a valve job. The exhaust port was sized for a 1 5/8" OD header primary (the larger of the two available tri-y headers for the Triumph TR8). With intake porting, these heads are supposedly capable of over 300 CFM which is a bunch for a Rover cylinder head.
Dan Jones
Given that the Huffaker single plane intake manifold is a perfect match for the GM 215 race heads (which use the larger Buick 300 ports but have the smaller Buick 215/Rover combustion chambers), I've often wondered if Huffaker didn't have some engines running the GM race heads:
I didn't have any shots showing the Rover 3.9L ports handy so I took a couple pictures today. Notice how narrow the exhaust port is. It will be interesting to see how well it flows through that tiny port.
> So, interesting to see your photos of the Rover castings modified for Autocross - - and suspect they'd be further improved if shaped similarly to the Nissan/Datsun L4 heads created by Tony Knight of Adelaide and featured here a couple of weeks ago
They might and I'm sure they would benefit from some additional exhaust side porting but these are only going to be used on the temporary/back up engine so will be freshened and run as is. The primary engine will get a ported set of the TA Performance Rover heads. They also have a quench style combustion chamber and flow roughly double what an unported OEM Rover head does:
They received a bowl porting and chamber polishing. On the intake side, only a minor amount of material was removed to match the ports to the Willpower single plane intake manifold (drilled for EFI):
The exhaust ports received the bulk of the porting and were enlarged to fit larger 1 5/8" primary tri-y headers (Kirk Racing design as sold by Woody Cooper of the The Wedge Shop and Ted Schumacher at TSI):
Heads were ported by Bob Stiegemeier of Stiegemeier Porting Service (http://stiegemeier.com/) in St. Charles, Missouri USA and were tested at a 28" pressure drop on a SuperFlow 600 flow bench. Intake ports were flowed with a clayed radius around the intake port. No pipe was used on the exhaust. Flow is in cubic feet per minute (CFM) and lift is in inches. Intake valve diameter is 1.94" and exhaust diameter is 1.6". Note that the heads were purchased assembled and Bob worked around the existing valve job. For my application, only minor work was required on the intake side so most of the effort was concentrated on the exhaust. Heads were flowed unported, ported and ported with a 30 degree back cut on the intake valves. Columns are as follow:
1 = out of box intake ports
2 = ported intake, no back cut on intake valves
3 = ported intake, 30 degree back cut on intake valves
4 = out-of-box exhaust ports, no pipe stub
5 = ported exhaust, no back cut on exhaust valves, no pipe stub
<pre>
Code: Select all
Valve 1 2 3 4 5
Lift 1.94 1.94 1.94 1.60 1.60
(Inch) CFM CFM CFM CFM CFM
0.100 67.7 76.8 78.3 47.9 63.8
0.200 105.4 120.4 129.4 70.2 108.5
0.300 143.0 173.1 185.1 102.1 146.7
0.350 164.0 198.7 206.2 114.9 -----
0.400 185.1 224.2 225.8 126.0 177.0
0.500 220.9 255.9 251.3 137.2 189.8
0.600 225.8 ----- 252.8 140.4 199.4
Bob noted the flow for the ported intake with back-cut valves was for the first one he did. He got closer to 260 CFM peak on subsequent valves. He believes he can do better if starting with heads without a valve job. The exhaust port was sized for a 1 5/8" OD header primary (the larger of the two available tri-y headers for the Triumph TR8). With intake porting, these heads are supposedly capable of over 300 CFM which is a bunch for a Rover cylinder head.
Dan Jones
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Re: Rover 3.9 heads, how much metal for porting?
I wouldn't doubt it.Given that the Huffaker single plane intake manifold is a perfect match for the GM 215 race heads (which use the larger Buick 300 ports but have the smaller Buick 215/Rover combustion chambers), I've often wondered if Huffaker didn't have some engines running the GM race heads:
1 5/8" is big for those power levels. A custom, modern racing header would likely be 1 1/2 off the head.
-Bob
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Re: Rover 3.9 heads, how much metal for porting?
Sorted it:
Before - now
.1 - 59.7 - 60.5
.2 - 125 - 126.5
.3 - 175.5 - 173.5
.4 - 204.5 - 206.5
.45 - 215 - 217
.5 - 213 - 221
.55 - 212 - 223
.6 - 215 - 225
.65 - 218.5 - 228
.7 - 221 - 229
.75 - 223 - 232
.8 - 225 - 234
.85 - 226 - 235
That'll do, not pushing my luck any further!
Before - now
.1 - 59.7 - 60.5
.2 - 125 - 126.5
.3 - 175.5 - 173.5
.4 - 204.5 - 206.5
.45 - 215 - 217
.5 - 213 - 221
.55 - 212 - 223
.6 - 215 - 225
.65 - 218.5 - 228
.7 - 221 - 229
.75 - 223 - 232
.8 - 225 - 234
.85 - 226 - 235
That'll do, not pushing my luck any further!
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Re: Rover 3.9 heads, how much metal for porting?
> 1 5/8" is big for those power levels.
What power levels are you assuming? If I assume 100% volumetric efficiency for a street tri-y, PipeMax suggests 1.594" primary and 1.719" secondary. If I assume 110% VE, those decrease 1.549" and 1.674" with a collector diameter between 2.403" to 2.653". For off-the-shelf Triumph TR8 headers, there are two choices:
Standard: 1 1/2" diameter primary, 1 3/4" secondary, 2" collector
Big Tube: 1 5/8" diameter primary, 1 7/8" secondary, 2 1/4" collector
> A custom, modern racing header would likely be 1 1/2 off the head.
Since the TA Performance Rover heads have a raised exhaust port location, the off-the-shelf TR8 headers will need to be altered anyway. I could cut off the flange of the bigger tube version and use a 1 1/2" flange. However, those are too small for the exhaust port which was ported to a 1 5/8" flange. For my strictly street toy, fully custom headers are not in the budget. I've not tested the stainless steel mufflers that came with the car but they were part of the smaller tube package and are likely restrictive. I plan to test Magnaflows on the dyno.
> That'll do, not pushing my luck any further!
Excellent results! What's the rest of the engine build look like?
Dan Jones
What power levels are you assuming? If I assume 100% volumetric efficiency for a street tri-y, PipeMax suggests 1.594" primary and 1.719" secondary. If I assume 110% VE, those decrease 1.549" and 1.674" with a collector diameter between 2.403" to 2.653". For off-the-shelf Triumph TR8 headers, there are two choices:
Standard: 1 1/2" diameter primary, 1 3/4" secondary, 2" collector
Big Tube: 1 5/8" diameter primary, 1 7/8" secondary, 2 1/4" collector
> A custom, modern racing header would likely be 1 1/2 off the head.
Since the TA Performance Rover heads have a raised exhaust port location, the off-the-shelf TR8 headers will need to be altered anyway. I could cut off the flange of the bigger tube version and use a 1 1/2" flange. However, those are too small for the exhaust port which was ported to a 1 5/8" flange. For my strictly street toy, fully custom headers are not in the budget. I've not tested the stainless steel mufflers that came with the car but they were part of the smaller tube package and are likely restrictive. I plan to test Magnaflows on the dyno.
> That'll do, not pushing my luck any further!
Excellent results! What's the rest of the engine build look like?
Dan Jones
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Re: Rover 3.9 heads, how much metal for porting?
It's a shame you guys are stuck with such large diameter valve stems on these things....
Re: Rover 3.9 heads, how much metal for porting?
That's a hint, right?
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.
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Re: Rover 3.9 heads, how much metal for porting?
Again, Nissan 260Z Turbo valves including oversizes, with Porsche guides for the smaller valve stems and original guide bores