The most definitive figures I have is before the roller over of power production starts to kick in is 60mm ~ 300hp, 65mm is about 350hp, 70mm is about 400hp.
Of course you can make more hp at these sizes but the engine needs to be more wild and the returns become of the diminishing kind.
More cylinders and or larger plenum will allow the throttle to work with more efficiency and therefore more power for the given size ( only if the TB is the limiting factor). Inversely this is why ITBs need to be so big to even work well. The CFM figures don't mean crap if the efficiency or pseudo "duty cycle" of the throttle is low or lower than idea. It's all to do with pulsed vs continuous flow and the limit of the speed of sound.
Holden 304 Banana Manifold
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vlad01
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Re: Holden 304 Banana Manifold
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
Re: Holden 304 Banana Manifold
https://www.mxengines.com.au/component/ ... gory_id=59
Maybe give this guy a call. He provides boring service on throttle bodies for motorbikes. Can't see why he couldn't do one for a car. If you need a throttle plate made, let me know what size and thickness etc. I have a mate who does precision laser cutting who likes to do cashies for me and doesn't charge much for his services.
Maybe give this guy a call. He provides boring service on throttle bodies for motorbikes. Can't see why he couldn't do one for a car. If you need a throttle plate made, let me know what size and thickness etc. I have a mate who does precision laser cutting who likes to do cashies for me and doesn't charge much for his services.
Re: Holden 304 Banana Manifold
Small update. Hopefully won’t get bagged out too much.
I got no where trying to get these manifolds flow tested, so thought I would stuff around to see if I could quantify any flow improvement in these ported manifolds myself. I didn’t have a stock manifold, so borrowed one from a mate – it is an untouched manifold from a VS Series 3 ute (so a VT era one).
My initial thoughts were to bolt up a stock throttle body complete with intake hose, air box (from a VS V6) and MAF sensor with the intention of recording MAF frequency once each runner was connected to a vacuum source. By chance I have 2 Miele vacuum cleaners which have an alleged flow rate of 140 cfm each. One vacuum cleaner wasn’t going to cut it so I connected the two up together with a Y piece and rigged this up on each port on the manifold with the throttle body fixed wide open. It was a huge assumption is that these 2 vacuum cleaners flow 280 cfm combined and I later found that they don’t. If they did, I should have gone beyond the runners flow capacity and hit higher vacuum readings. Anyway what I found was the MAF frequency pretty much stays the same, and it’s the vacuum in the runner that changes. So I guess in reality what should occur is that you would vary the flow through each runner until you a draw a set vacuum, which would be -28”H2O (or -2”Hg) and record the MAF frequency. But this is something I can’t really do with what I have.
So with no other reasonable options, I have instead I measured the vacuum 2.5” down into each runner where it is becomes round, with the assumed 280 cfm from two vacuum cleaners passing through it. Another assumption is that the lower the vacuum, the lower the restriction and the higher the flow potential. Unfortunately the manometer I have has pretty poor resolution (around 0.4” H2O) but I have measured each runner for its vacuum referenced to the throttle body and again for outright vacuum with no reference. I ended up just using the outright vacuum figures as these seemed more consistent.
I’m not going to pretend that any of this is clinically accurate rocket surgery, but it’s better than nothing. But what I found was that there was a significant difference in vacuum across the runners on each manifold tested, but the difference was much less for the mildly ported and heavily ported manifolds.
So what I found is below:
The average runner vacuum on the stock manifold is 16.00” H2O. Cylinder #5 was the worst at 18.6" H2O, and Cylinder #7 was the best. Difference between best and worst was 6.2” H2O.
The average runner vacuum on the mildly ported manifold is 11.10” H2O. Cylinder #1 was the worst, Cylinder #3 was the best. Difference between best and worst was 2.4” H2O.
The average runner vacuum on the heavily ported manifold is 10.30” H2O. Cylinder #6 is now the worst and Cylinder #3 still the best. Difference between best and worst was 1.90” H2O.
I always assumed that Cyl #1 runner would be the worst as it has a pretty ordinary path to follow to get to the throttle body through the neck, and it wasn’t until I cleaned up the runners that this became true. And while the heavily ported manifold has all the ports flowing closer to each other, this may not be the case if I could crank more flow through it. Another observation is that if I put a bit more work into Cyl #1 on the mildly ported manifold, all vacuum readings would be pretty close together, possibly better than the heavily ported manifold.
I guess all this is arguably meaningless as the figures only mean something to me, but the real standout out from this is how much of an improvement there was with just the mildly ported manifold. The ports are in reality only about 0.5mm bigger, but the improvement in flow is potentially huge so most of that must be coming from the improvement in the bell mouths.
I got no where trying to get these manifolds flow tested, so thought I would stuff around to see if I could quantify any flow improvement in these ported manifolds myself. I didn’t have a stock manifold, so borrowed one from a mate – it is an untouched manifold from a VS Series 3 ute (so a VT era one).
My initial thoughts were to bolt up a stock throttle body complete with intake hose, air box (from a VS V6) and MAF sensor with the intention of recording MAF frequency once each runner was connected to a vacuum source. By chance I have 2 Miele vacuum cleaners which have an alleged flow rate of 140 cfm each. One vacuum cleaner wasn’t going to cut it so I connected the two up together with a Y piece and rigged this up on each port on the manifold with the throttle body fixed wide open. It was a huge assumption is that these 2 vacuum cleaners flow 280 cfm combined and I later found that they don’t. If they did, I should have gone beyond the runners flow capacity and hit higher vacuum readings. Anyway what I found was the MAF frequency pretty much stays the same, and it’s the vacuum in the runner that changes. So I guess in reality what should occur is that you would vary the flow through each runner until you a draw a set vacuum, which would be -28”H2O (or -2”Hg) and record the MAF frequency. But this is something I can’t really do with what I have.
So with no other reasonable options, I have instead I measured the vacuum 2.5” down into each runner where it is becomes round, with the assumed 280 cfm from two vacuum cleaners passing through it. Another assumption is that the lower the vacuum, the lower the restriction and the higher the flow potential. Unfortunately the manometer I have has pretty poor resolution (around 0.4” H2O) but I have measured each runner for its vacuum referenced to the throttle body and again for outright vacuum with no reference. I ended up just using the outright vacuum figures as these seemed more consistent.
I’m not going to pretend that any of this is clinically accurate rocket surgery, but it’s better than nothing. But what I found was that there was a significant difference in vacuum across the runners on each manifold tested, but the difference was much less for the mildly ported and heavily ported manifolds.
So what I found is below:
The average runner vacuum on the stock manifold is 16.00” H2O. Cylinder #5 was the worst at 18.6" H2O, and Cylinder #7 was the best. Difference between best and worst was 6.2” H2O.
The average runner vacuum on the mildly ported manifold is 11.10” H2O. Cylinder #1 was the worst, Cylinder #3 was the best. Difference between best and worst was 2.4” H2O.
The average runner vacuum on the heavily ported manifold is 10.30” H2O. Cylinder #6 is now the worst and Cylinder #3 still the best. Difference between best and worst was 1.90” H2O.
I always assumed that Cyl #1 runner would be the worst as it has a pretty ordinary path to follow to get to the throttle body through the neck, and it wasn’t until I cleaned up the runners that this became true. And while the heavily ported manifold has all the ports flowing closer to each other, this may not be the case if I could crank more flow through it. Another observation is that if I put a bit more work into Cyl #1 on the mildly ported manifold, all vacuum readings would be pretty close together, possibly better than the heavily ported manifold.
I guess all this is arguably meaningless as the figures only mean something to me, but the real standout out from this is how much of an improvement there was with just the mildly ported manifold. The ports are in reality only about 0.5mm bigger, but the improvement in flow is potentially huge so most of that must be coming from the improvement in the bell mouths.
Re: Holden 304 Banana Manifold
The only photo I took was of the Y piece. I've disassembled everything now and I'm not going to lie there was some duct tape used 
I'm not an XL guru, but here is a spreadsheet though where I have put the values.
- Y Piece.JPG (79.32 KiB) Viewed 2503 times
- Spreadsheet.JPG (92.75 KiB) Viewed 2503 times
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Charlescrown
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Re: Holden 304 Banana Manifold
A work mate made up a flow bench and we tried using vacuum cleaners and they were hopless so we ended up with a huge industrial motor which did the job. I hope you can do it with vacuum cleaners.
Re: Holden 304 Banana Manifold
The other option I tried was the dust collector from a bead blasting cabinet which has a 4” inlet pipe. It probably has a greater volume, but couldn’t really pull much of a vacuum.
Re: Holden 304 Banana Manifold
Instructables.com has a pretty good info for building DIY flow bench.
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Re: Holden 304 Banana Manifold
Another minor update.
I have got hold of a bored out throttle body and am ready to fit the mildly ported banana manifold to an engine and do some before and after testing.
A bit about the test car - my grandpa spec VT Calais which happily sits in the shed with a flat battery. It’s an April 99 model so towards the last of the 5.0s. I would have been lucky to do 2000 kms in it since I bought it a few years back which is another reason I am not so keen on adding another 1200kms just for some dyno testing. It does have a few miles on it already but is close to immaculate with leather interior, beautiful to drive and is pretty much stock other than a set of R8 rims and a dual 2.25” XForce catback that I fitted not long after I got it.
I did have hopes that my eldest daughter would use it for her formal car when she finishes school, but there’s a big block HQ 2 door Monaro that she thinks will be a better option. I think she would rather walk than be seen in the Calais which might as well be a beige Camry as far as she is concerned. Luckily I have a couple of nephews with good taste who are keen to inherit it one day.
Regardless, this Calais can actually be pretty good on fuel on the highway, and the best I have seen on the trip computer was 8.0 litres/100km. It has a nice exhaust note and is not too loud, and is really comfortable. It has the factory 179 kw roller cam, stock Bosch 973 injectors, stock exhaust manifolds and cats. Diff gears and transmission are stock. As far as I know, it has never had the heads off, but the intake manifold has been changed at some stage as it has an earlier manifold on it with a bung in the MAT port. No idea why and all I can think of is they must have swapped it doing the valley gaskets years back. Either that or the original one was porous in some way. Interestingly this Calais has the HSV CNPK memcal from the factory. Matters not. Springs, struts and shocks are all original, not that wheel spin or getting off the line is going to be a problem.
But while it is nice to drive, it is absolutely gutless. So another reason why it’s not the best candidate for testing a ported manifold but it’s what I have. It’s a shame really as a dyno test on this would have been good for a laugh.
I guess some will say the 2.25” exhaust would be limiting the hp and any normal person would have gone the dual 2.5” or dual 3”, but my personal opinion is that the smaller pipes sound better. Power wasn’t a consideration as this thing is lucky to hit 3000 rpm when I do drive it so dual 2.25” pipes are more than enough coasting around town or along the highway.
I have ordered an NVRAM loaded with the enhanced bin, and have fitted this with the revised table to the Default Air Flow vs TPS so the transmission doesn’t play up with the bigger throttle. But the fuel and ignition tables etc are all stock.
To date, I have done 4 runs on the same stretch of road with the stock manifold and throttle body, and repeated this again with the 70mm throttle body.
What I found is possibly what everyone else already knew - that there is only a small gain fitting a 70mm throttle over the stock 65mm. But to be fair though it was a much hotter ambient on the night I tested the 70mm throttle, and the trans slip on the gear changes seemed a little worse. Maybe if the ambient temp was the same for both tests, the 70mm throttle would look a bit better.
The main thing that I noticed with the 70mm throttle is that it sticks open and didn’t want to close. With the engine stopped, it’s completely fine, opens and fully returns to a close and repeats this every time. But start the engine and it just doesn’t want to return home to fully closed. Almost as if engine vacuum is holding it open. I have heard of issues with these bored throttles sticking, but always thought it was due to a problem in the throttle shaft but that’s not the case here. I’ll sure smarter blokes than me have looked at this but I managed to get it working fine by cranking up the spring tension on it a little.
But at the moment, the improvement from a 70mm throttle isn’t enough that I would keep it on there – not on a stock Calais anyway. If it was a manual, then possibly worth the effort.
This is it fitted with 70mm throttle. In the photo you can see where I have moved the spring around to the next position to get it to return.
Next step is to fit the mildly ported manifold and get some more times with both the stock 65mm and 70mm throttle body. I have made a start already and have the coolant out ready to attack it. Will replace all the heater hoses while I am at it and obviously give it an oil change.
To be honest I was expecting a better result from the bored out throttle body. So now I have a bad feeling that based on what I have seen so far that getting some 0 to 100km times won't prove anything – which is probably again what everyone else already knows. Maybe a bit more cam and compression might be a different story, but I’m thinking it’s pretty unlikely that a ported manifold on a stock 5.0 will show any gains at the same rpms as an unported one. So unless you wring its neck a little more with some higher rpms, you won’t see any gains in 0 to 100km/hr times whereas a dyno would probably show this.
Anyway, I will press on as I have no other options. Good or bad, faster or slower will post up what I find.
But this is the results so far.
I have got hold of a bored out throttle body and am ready to fit the mildly ported banana manifold to an engine and do some before and after testing.
A bit about the test car - my grandpa spec VT Calais which happily sits in the shed with a flat battery. It’s an April 99 model so towards the last of the 5.0s. I would have been lucky to do 2000 kms in it since I bought it a few years back which is another reason I am not so keen on adding another 1200kms just for some dyno testing. It does have a few miles on it already but is close to immaculate with leather interior, beautiful to drive and is pretty much stock other than a set of R8 rims and a dual 2.25” XForce catback that I fitted not long after I got it.
I did have hopes that my eldest daughter would use it for her formal car when she finishes school, but there’s a big block HQ 2 door Monaro that she thinks will be a better option. I think she would rather walk than be seen in the Calais which might as well be a beige Camry as far as she is concerned. Luckily I have a couple of nephews with good taste who are keen to inherit it one day.
- Calais.JPG (134.03 KiB) Viewed 1778 times
But while it is nice to drive, it is absolutely gutless. So another reason why it’s not the best candidate for testing a ported manifold but it’s what I have. It’s a shame really as a dyno test on this would have been good for a laugh.
I guess some will say the 2.25” exhaust would be limiting the hp and any normal person would have gone the dual 2.5” or dual 3”, but my personal opinion is that the smaller pipes sound better. Power wasn’t a consideration as this thing is lucky to hit 3000 rpm when I do drive it so dual 2.25” pipes are more than enough coasting around town or along the highway.
I have ordered an NVRAM loaded with the enhanced bin, and have fitted this with the revised table to the Default Air Flow vs TPS so the transmission doesn’t play up with the bigger throttle. But the fuel and ignition tables etc are all stock.
To date, I have done 4 runs on the same stretch of road with the stock manifold and throttle body, and repeated this again with the 70mm throttle body.
What I found is possibly what everyone else already knew - that there is only a small gain fitting a 70mm throttle over the stock 65mm. But to be fair though it was a much hotter ambient on the night I tested the 70mm throttle, and the trans slip on the gear changes seemed a little worse. Maybe if the ambient temp was the same for both tests, the 70mm throttle would look a bit better.
The main thing that I noticed with the 70mm throttle is that it sticks open and didn’t want to close. With the engine stopped, it’s completely fine, opens and fully returns to a close and repeats this every time. But start the engine and it just doesn’t want to return home to fully closed. Almost as if engine vacuum is holding it open. I have heard of issues with these bored throttles sticking, but always thought it was due to a problem in the throttle shaft but that’s not the case here. I’ll sure smarter blokes than me have looked at this but I managed to get it working fine by cranking up the spring tension on it a little.
But at the moment, the improvement from a 70mm throttle isn’t enough that I would keep it on there – not on a stock Calais anyway. If it was a manual, then possibly worth the effort.
This is it fitted with 70mm throttle. In the photo you can see where I have moved the spring around to the next position to get it to return.
To be honest I was expecting a better result from the bored out throttle body. So now I have a bad feeling that based on what I have seen so far that getting some 0 to 100km times won't prove anything – which is probably again what everyone else already knows. Maybe a bit more cam and compression might be a different story, but I’m thinking it’s pretty unlikely that a ported manifold on a stock 5.0 will show any gains at the same rpms as an unported one. So unless you wring its neck a little more with some higher rpms, you won’t see any gains in 0 to 100km/hr times whereas a dyno would probably show this.
Anyway, I will press on as I have no other options. Good or bad, faster or slower will post up what I find.
But this is the results so far.
- Recorded Times.JPG (32.59 KiB) Viewed 1778 times
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immortality
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Re: Holden 304 Banana Manifold
Nice ride.
Yeah, looking at the MAF Hz there is basically no increase in flow so the 65mm TB isn't the restriction as far as overall airflow goes. All it will do is make the throttle more sensitive, more air for a given throttle %age at low throttle openings.
Definitely be interesting to see if the manifold makes any changes.
One thing I'm a bit dubious about on the VT-VY models is the little cold air intake snorkel that sits above the radiator cowling panel, with the bonnet closed where does it get it's air cold from?
Yeah, looking at the MAF Hz there is basically no increase in flow so the 65mm TB isn't the restriction as far as overall airflow goes. All it will do is make the throttle more sensitive, more air for a given throttle %age at low throttle openings.
Definitely be interesting to see if the manifold makes any changes.
One thing I'm a bit dubious about on the VT-VY models is the little cold air intake snorkel that sits above the radiator cowling panel, with the bonnet closed where does it get it's air cold from?