Are these Single point 'cooker-ring' mixers more snake-oil?

[Gilbertd]

Is that V8 powered boats on LPG? LPG I'd guess is a safe fuel for boats - less of a fire hazard than petrol

Most ski boats used on inland lakes run on LPG as nobody wants to be gassed with petrol exhaust fumes when being dragged around on the end of a piece of string by a V8 powered boat. Many also use a Lexus V8 which is all alloy but with an open cooling system, so they are only suitable for inland use. Using an open cooling system in salt water with an alloy engine means it wouldn't be long before it dissolved. That's why most inboard boat engines use geriatric American cast iron engines as a closed cooling system with a heat exchanger makes it more complex (and boat owners don't do complex, they seem to regard the engine as that black thing that lives under a cover in the back that never gets any attention). Simon's has a 5.3 litre Ford Windsor V8, mine has a 4.3 litre small block Chevy V6.

[LPGC]

Simon's has a 5.3 litre Ford Windsor V8, mine has a 4.3 litre small block Chevy V6.

My Ford Windsor V8 is the most common 302cubic inch size with 4inch bore and 3 inch stroke known as the 5.0 or 5litre since the 80's but was really a 4.949litre. Mine's overbored by 40thou so is 307.65 cubic inches (5.03litres).

They originally made a 289 Windsor but the smallest size soon became 302. The other common size for Windsors and made over the same time period as the 302 (60's to around 1997) is the 351cubic inch (5.8 litre) with 4 inch bore and 3.5inch stroke. The 351 has taller decks than the 302 to allow for the longer stroke, also has bigger crankshaft main bearings (so you can't really deck a 351 and use a 302 crank to turn it into a 302). The taller deck also means the inlet manifold is wider and the sparks distributor is longer, the sump is deeper to allow for the bigger main bearings and the oil pump is different. Depending on year the balancing (harmonic damper and flywheel) are different. Turns out the only parts interchangeable between a 302 and 351 are pistons, cylinder heads and assorted bolts lol, yet a 351 and 302 will bolt up to the same mounts, exhaust (though the 2 halves spaced a bit wider apart) and transmission. I looked into all this when deciding whether to rebuild my engine or fit a different one, in the end I rebuilt my 302. I would've liked to have had the 351 and at the time they were more available in the UK than 302s but most of them came with truck oil pans that had the sump at the front (need the sump at the back on a boat), without a distributor and/or inlet manifold. I'm happy I rebuilt mine instead of fitting a 351 now, because apparently the 351 uses disproportionally more fuel than the 302 (like 16% bigger and 16% more torque, but a smaller figure for extra hp and a bigger figure increased fuel use), some of this due to the bigger main bearings having more friction.

There are plenty ways to increase power on all the cast iron V6 and V8 engines, having been made for so long and so popular/numerous fitted in vehicles like Camaros/Mustangs etc there are plenty bolt on upgrades ranging from simple carb and inlet manifold swaps, cam swaps, rocker ratios, up to long stroke cranks, aftermarket aluminium heads, etc. A modern day made aftermarket aluminium head will flow better than any of the old cast iron heads including all the 'special' performance heads of the time (such as GT40 heads in the case of the Windsor). But for a boat application it's said to be a bad idea to fit a camshaft that opens valves for longer duration because with longer exhaust valve duration any condensation inside the exhaust manifolds can run backwards into cylinders during starting and cause hydraulic lock, so the marine application can still limit you in terms of some things you could do in terms of tuning. As Gilbert said we don't want saltwater flowing through aluminium heads, especially not when they're bolted to an iron block. When I had the engine out I did think about converting my setup to closed cooling using a water to water heat exchanger setup (so only the exhaust manifolds would be salt water cooled), it would've given the advantage of being able to run most car/truck spec Windsor engines (late spec water pump instead of the cast iron water pump, use the later spec roller hydraulic cam instead of flat hydraulic cam, etc) so there'd be a bit of a power boost anyway and parts availability would be easier in future, could also have fitted aluminium heads instead of reconditioning my heads. With the 351 or a few mods on my 302 it would've cracked 50mph which would've been nice but at 47mph it's not slow as it is and open water cruising speed will usually be closer to 30mph anyway unless I want to watch the fuel gauge moving quickly.

[Pinger]

Is that V8 powered boats on LPG? LPG I'd guess is a safe fuel for boats - less of a fire hazard than petrol

Most ski boats used on inland lakes run on LPG as nobody wants to be gassed with petrol exhaust fumes when being dragged around on the end of a piece of string by a V8 powered boat. Many also use a Lexus V8 which is all alloy but with an open cooling system, so they are only suitable for inland use. Using an open cooling system in salt water with an alloy engine means it wouldn't be long before it dissolved. That's why most inboard boat engines use geriatric American cast iron engines as a closed cooling system with a heat exchanger makes it more complex (and boat owners don't do complex, they seem to regard the engine as that black thing that lives under a cover in the back that never gets any attention). Simon's has a 5.3 litre Ford Windsor V8, mine has a 4.3 litre small block Chevy V6.

As you are aware, the GM Vortec I have has the 'spider' injection and a modification to be rid of it is to use the (very scarce) marine inlet manifold which uses external injectors and fuel rails. It took me a while to figure out why it cast in iron...

[Pinger]

Simon's has a 5.3 litre Ford Windsor V8, mine has a 4.3 litre small block Chevy V6.

My Ford Windsor V8 is the most common 302cubic inch size with 4inch bore and 3 inch stroke known as the 5.0 or 5litre since the 80's but was really a 4.949litre. Mine's overbored by 40thou so is 307.65 cubic inches (5.03litres).

They originally made a 289 Windsor but the smallest size soon became 302. The other common size for Windsors and made over the same time period as the 302 (60's to around 1997) is the 351cubic inch (5.8 litre) with 4 inch bore and 3.5inch stroke. The 351 has taller decks than the 302 to allow for the longer stroke, also has bigger crankshaft main bearings (so you can't really deck a 351 and use a 302 crank to turn it into a 302). The taller deck also means the inlet manifold is wider and the sparks distributor is longer, the sump is deeper to allow for the bigger main bearings and the oil pump is different. Depending on year the balancing (harmonic damper and flywheel) are different. Turns out the only parts interchangeable between a 302 and 351 are pistons, cylinder heads and assorted bolts lol, yet a 351 and 302 will bolt up to the same mounts, exhaust (though the 2 halves spaced a bit wider apart) and transmission. I looked into all this when deciding whether to rebuild my engine or fit a different one, in the end I rebuilt my 302. I would've liked to have had the 351 and at the time they were more available in the UK than 302s but most of them came with truck oil pans that had the sump at the front (need the sump at the back on a boat), without a distributor and/or inlet manifold. I'm happy I rebuilt mine instead of fitting a 351 now, because apparently the 351 uses disproportionally more fuel than the 302 (like 16% bigger and 16% more torque, but a smaller figure for extra hp and a bigger figure increased fuel use), some of this due to the bigger main bearings having more friction.

There are plenty ways to increase power on all the cast iron V6 and V8 engines, having been made for so long and so popular/numerous fitted in vehicles like Camaros/Mustangs etc there are plenty bolt on upgrades ranging from simple carb and inlet manifold swaps, cam swaps, rocker ratios, up to long stroke cranks, aftermarket aluminium heads, etc. A modern day made aftermarket aluminium head will flow better than any of the old cast iron heads including all the 'special' performance heads of the time (such as GT40 heads in the case of the Windsor). But for a boat application it's said to be a bad idea to fit a camshaft that opens valves for longer duration because with longer exhaust valve duration any condensation inside the exhaust manifolds can run backwards into cylinders during starting and cause hydraulic lock, so the marine application can still limit you in terms of some things you could do in terms of tuning. As Gilbert said we don't want saltwater flowing through aluminium heads, especially not when they're bolted to an iron block. When I had the engine out I did think about converting my setup to closed cooling using a water to water heat exchanger setup (so only the exhaust manifolds would be salt water cooled), it would've given the advantage of being able to run most car/truck spec Windsor engines (late spec water pump instead of the cast iron water pump, use the later spec roller hydraulic cam instead of flat hydraulic cam, etc) so there'd be a bit of a power boost anyway and parts availability would be easier in future, could also have fitted aluminium heads instead of reconditioning my heads. With the 351 or a few mods on my 302 it would've cracked 50mph which would've been nice but at 47mph it's not slow as it is and open water cruising speed will usually be closer to 30mph anyway unless I want to watch the fuel gauge moving quickly.

I'm a big fan of large capacity American V8s - the next simplest engine after a 2-stroke! - prodigious thirst their only demerit but to be fair, hauling my 2700kg Suburban around, nothing is going to be frugal. It's testament to that Vortec that the 2700kg isn't more noticeable. Low end torque to die for.
It is remarkable the life span (eg, 60s to 07 Windsor, GM SBC are similarly long lived) of these units. Pretty much everything you say of the Windsor is true for SBCs also re tuning and versatility. Guys on the GMT400 are running engines with all sorts of power outputs - often quite a bit more than as standard. But always with the application in mind - from towing in the mountains or destroying a 1/4 mile strip. The American 'can-do' attitude is alive and kicking.

Good to hear of the progress on your boat engine and that you're happy with the direction you took. I'm in favour of rebuilding and then knowingexactly what you have. Used is fine - but can easily be X amount of years of someone else's stored up problems.

[LPGC]

Yes, I meant all the old iron engines are easy to modify for increased power/torque... But part of that is because they didn't make much power for their size in the first place lol.

There was a 'Boss 302' which uses the Windsor block and rotating assembly with Cleveland heads which back in the day flowed better than Windsor heads. They made some production Boss302's but they originally came about when a Ford manager had mechanics create a hybrid engine just for his own car using the stronger Windsor bottom end with the better breathing Cleveland heads, some modification to allow the heads to fit the block and a custom inlet manifold. But although the Cleveland heads are cast iron they wouldn't be any good for marine use because they don't make marine exhaust manifolds to match the Cleveland heads.

Before I decided to rebuild my existing engine I looked at a few engines in various conditions and with various mods. It was difficult to find just a second hand known good 302 or even 351, it would have been easier to find/buy a rebuilt and modified 302 than a known good second hand one. Seems when they were available engine builders bought them and immediately rebuilt them adding aluminium heads, big cams and shiny bits like water pumps, none of which would have been much use for the boat unless I converted it to closed cooling. The engines seemed to be in demand and I did consider importing a few from the US over winter to sell at a profit but decided it would've been a bad idea. I nearly bought a supposedly known good 351 that was available in Cornwall but it was missing the distributor and it had a front sump. Went to look at a 351 in bits locally but that also had front sump and would've needed at least a rebore and new pistons anyway, it was also none hydraulic flat tappet cam which I didn't fancy. Had a better starting point with the engine I already had and which I'd heard run.

Evolution of marine engines is slower in many respects than vehicle engines, sometimes with good reason, sometimes not. My boat is a '96 model and the Windsors were still the current Ford small block in '96 so I can understand the use of this engine, I can also understand why they used the 1970's spec water pump, but by 1996 the car and truck versions had been using hydraulic roller cam setups for a long time while the marine version of this engine continued to use a flat tappet hydraulic cam... still hydraulic but not roller. Unless you're going to use uprated valve springs etc the roller cam setups are better for high rpm use, better in general really because the cams last longer especially with modern low zinc oils. The red line on this engine with it's standard valve springs is only around 4500rpm.

[Pinger]

Evolution of marine engines is slower in many respects than vehicle engines, sometimes with good reason, sometimes not. My boat is a '96 model and the Windsors were still the current Ford small block in '96 so I can understand the use of this engine, I can also understand why they used the 1970's spec water pump, but by 1996 the car and truck versions had been using hydraulic roller cam setups for a long time while the marine version of this engine continued to use a flat tappet hydraulic cam... still hydraulic but not roller. Unless you're going to use uprated valve springs etc the roller cam setups are better for high rpm use, better in general really because the cams last longer especially with modern low zinc oils. The red line on this engine with it's standard valve springs is only around 4500rpm.

I'd kinda forgotten it was Windsor all the way until the Modular 4.6l replaced it. All alloy, not much use for offshore boating (without a closed cooling system).
I see exactly the same in GM land with the roller set-up being the preferred option and a change-over point in production that saw some blocks equipped with provisions for roller cam but with a flat tappets. Presumably a temporary supply logistics issue. There is also always a lot of discussion around the running in of flat tappet motors re the 'zinc'.
I'd not call my Vortec a 'rev monster' but it will run to 5500 happily (as it did yesterday). Your 4500 limit does seem low. Is that on account of a cam that prioritises low end torque over everything, that torque being required to get the boat 'out of the hole' and planing?

[CNG]

SU-Mixer.gif (102.27 KiB) Viewed 3575 times

For a HIF44/ HS6 SU carb, does this mixer look right to you? By my calculations cross-sectional area drops from:

44mm = 1520.53 sq.mm

to...

32mm = 804.25 sq. mm

ie the cooker ring knocks area by 47%. That much? That'd be half an engine gone? Surely not?

[Pinger]

Air (or any gas for that matter) will (obviously) speed up (and simultaneously) lose pressure passing through a venturi but, will on leaving it slow down again and regain its pressure without any loss of flow. That is only true though if there is no turbulence. Turbulence is energy squandered (to heat) that can never be recovered. Turbulence will occur when the velocity reaches a certain value. There is also a pressure drop across the venturi and when it reaches a critical threshold 'choked flow' ensues and no amount of increased downstream vacuum signal will increase flow. The only way flow can increase is if the upstream pressure is increased and even then the volumetric flow rate remains the same but the increased pressure increases the gas's density thus the mass flow can increase.
The whole lot is defined first by Bernoulli's Theorem and then by Reynold's Number.

[CNG]

Thanks Pinger. After writing, and pondering my own post, I started to think about gas speed. I return to find the bloke that studied fluid-dynamics when I was studying Transistor Transfer Characteristics! Most times, fluid-dynamics is more useful.

And yes, obvious really, of course,gas-speed increases. Hence that is the correct mixer.

[Pinger]

As a rule of thumb - Ricardo when investigating gas velocity in inlet ports found that peak volumetric efficiency occurred when the gas speed was 120-160 ft/s (37-50 m/s) and for SI engines the volumetric efficiency fell sharply at speeds of 240-260 ft/s (73-80 m/s), and at a slightly lower figure for CI engines. Presumably the lower figure for CI is due to the port imparting swirl motion (for the benefit of combustion) which inherently produces turbulence and hence lowers the gas speed at which turbulence becomes limiting.

[LPGC]

I'd not call my Vortec a 'rev monster' but it will run to 5500 happily (as it did yesterday). Your 4500 limit does seem low. Is that on account of a cam that prioritises low end torque over everything, that torque being required to get the boat 'out of the hole' and planing?

Apparently when Ford techs were looking for a way to increase power of the car/truck 302 Windsors lots of things were put forward but then one of the techs suggested just using the marine cam which made more power than the usual road going cams. The road going 5.0HO Mustang went on to use the same cam that was already used for the marine 302's, so quite the contrary to what we might expect. For sure other cams can make more top end power at the expense of bottom end torque, but I think they went with what we'd usually assume a torquey cam because the limiting factor was rpm due to the original valve train and potential valve float.

Not your fault but it seems I/we are talking a bit off subject on this particular thread, we could use the boat thread to continue to discuss this. I see you've been replying about the real subject of this thread lately (mixers etc) where-as I haven't so much lol.

[Pinger]

Apparently when Ford techs were looking for a way to increase power of the car/truck 302 Windsors lots of things were put forward but then one of the techs suggested just using the marine cam which made more power than the usual road going cams. The road going 5.0HO Mustang went on to use the same cam that was already used for the marine 302's, so quite the contrary to what we might expect. For sure other cams can make more top end power at the expense of bottom end torque, but I think they went with what we'd usually assume a torquey cam because the limiting factor was rpm due to the original valve train and potential valve float.

That, I'll wager, was for cost/logistics reasons as Ford by that time knew everything there was to know about valve train dynamics as having valve float problems racing the GT40 it commissioned a comprehensive study on the subject. It allowed them to get to grips with massive push rod operated valves in massive cylinders at high rpm. At the same time competitor Porsche was experiencing similar problems on piddly little cylinders with piddly little valves and OHC. Ford's guy on the GT40 programme offered to help Porsche but was rebuffed. Porsche went on to solve the problem itself (with some time delay though) and maybe there was Not Invented Here Syndrome first seen.

Not your fault but it seems I/we are talking a bit off subject on this particular thread, we could use the boat thread to continue to discuss this. I see you've been replying about the real subject of this thread lately (mixers etc) where-as I haven't so much lol.

What's a thread that can't meander!

[Gilbertd]

What's a thread that can't meander!

There's meandering and there's flying off at a tangent! However, boat engines are more interesting and the original question seems to have been answered anyway. My engine is the '96 Vortec SBC V6 fitted with a 2 barrel carb (progressive not sequential) which, according to Mercruiser (who call it the Gen+ engine), develops 190hp. They also did a 4 barrel carb equipped version, which they rated at 200hp, and later ones got single port injection (but still 200hp). As a Vortec, I've got the hydraulic roller cam followers (and balance shaft). As it has all been rebuilt with, amongst other new bits, +40 thou pistons, which have taken it from the original 4,299cc up to 4,360cc so should be good for 200hp even with the two barrel carb. Not sure what it will rev to but at 3,000 rpm it's up on the plane and doing 38 mph according to a GPS speedo (so only 31 mph over the blanket inland waterways speed limit). Now the weather and lack of daylight in the evenings mean it isn't likely to get any more use this year, I'm going to have to wait until next year before getting out on the sea to really open it up and see what it can do.

[LPGC]

What's a thread that can't meander?

True, and I don't care much either way tbh lol, but this isn't my thread and I just thought there is a ready thread we've been discussing boats on lately.

There's meandering and there's flying off at a tangent! However, boat engines are more interesting and the original question seems to have been answered anyway.

Lol, agreed on both counts, plus you're a moderator and I'm not

I was about to post some more videos either on this thread or the (ahem more relevant) boat thread but I'm just packing up for the day, I might post some when I'm settled indoors

[robertXX]

My only expereince with venturi's is the nomal mixer ring ones, with nothing in the middle , and the omvl ones wit the plastic ring you clip in that can be different sizes .

the biggest problem i have found with them is that , if i have the mixture right at the high rpm full throttle area , and also on the low rpm , and the cruise areas , then , if i go full throttle at say , 2000 rpm , the mixture leans right out at 3500 , then richens up again at 4000 ,mix is ok then to 6500 .

i have found this with every one i have used , ,i wonder if the rings with the centre feed would help with this ..?

of course it could be down to the omvl r90 e reducer ?


regards
robert

[Pinger]

All this has got me wondering what it would take to make LPG work with a lager venturi. After all, carbs manage larger and have no real problems pulling liquid fuel in from an obviously lower vacuum signal. Is it down to the additional circuits carbs have?

[Gilbertd]

the biggest problem i have found with them is that , if i have the mixture right at the high rpm full throttle area , and also on the low rpm , and the cruise areas , then , if i go full throttle at say , 2000 rpm , the mixture leans right out at 3500 , then richens up again at 4000 ,mix is ok then to 6500 .

The normal cause of this is having the stepper too far away from the mixer so it takes a while for the additional gas to get to where it needs to be. You floor the throttle and the stepper opens, assuming it needs to open, but that gas is in the hose and not in the manifold. My way of setting them up is to get the idle stepper opening in roughly the right area, 100 or slightly higher, by adjusting the main bias with the idle bleed closed off. Then raise the revs to 2,500-3,000rpm and adjust again to get the opening the same as at idle. Final test is to connect the laptop and take the car for a run, put it in Sport and floor the throttle. If the stepper still stays in the same area up to the red line, all is good, if it goes lean at higher revs then the vaporiser isn't man enough so not supplying sufficient when the maximum amount is needed. If the stepper opening is different in different rev ranges, then it can cause all sorts of weird problems particularly if you've got a long hose between stepper and mixer. I've got a pair of near identical 4.0 litre P38 Range Rovers, both using an R90E, one with a standard cooker ring mixer and one with one of the centre feed things and I've got them both so the stepper never needs to move much either side of 120 at all throttle openings and loads. In both cases there is around 3 inches of hose between the stepper and the mixer.

All this has got me wondering what it would take to make LPG work with a lager venturi. After all, carbs manage larger and have no real problems pulling liquid fuel in from an obviously lower vacuum signal. Is it down to the additional circuits carbs have?

Probably as carbs have slow running jets and accelerator pumps. My experience with a too large mixer was that I could get a sensible stepper opening at idle but it would go lean, or at least the stepper would have to open much more, when the throttle was open. No matter how much I adjusted the vaporiser could I get the same opening at out of idle to idle. The main bias on the vaporiser sets how much suck is needed for any particular stepper opening while the idle bleed just dribbles a constant (small) amount of gas in all the time. So you could get it to run at idle with a huge mixer (or just a bit of pipe hanging in the inlet) by opening the idle bleed but that would have next to no affect as soon as you open the throttle so it will go lean.

[LPGC]

My only expereince with venturi's is the nomal mixer ring ones, with nothing in the middle , and the omvl ones wit the plastic ring you clip in that can be different sizes .

the biggest problem i have found with them is that , if i have the mixture right at the high rpm full throttle area , and also on the low rpm , and the cruise areas , then , if i go full throttle at say , 2000 rpm , the mixture leans right out at 3500 , then richens up again at 4000 ,mix is ok then to 6500 .

i have found this with every one i have used , ,i wonder if the rings with the centre feed would help with this ..?

of course it could be down to the omvl r90 e reducer ?


regards
robert

That's interesting, I think I've seen this effect on some installs.

If the engine is using a certain amount of flow of intake air to make a certain amount of horsepower at (say) at 3500rpm full throttle when it goes lean, then I wonder if you ran the engine at 5000rpm but only at part throttle to make the same amount of power as at 3500rpm full throttle if it would still go lean at the same airflow. If we plotted a graph of airflow versus mixture would the lean mixture area always be around the same airflow regardless of rpm (so some nonlinearity from the mixer or reducer) or is the lean mixture area rpm related (could something like frequency of induction pulses play a part and if so would spacing the mixer further from the carb/throttle make response more linear).

Post crossed with Gilbert's, I took the question in context of open loop mixer and reducer response, I agree with Gilbert that stepper position and how the ECU controls the stepper can affect closed loop response. Another thing to keep in mind is that AEB175s will only aim for slightly rich mixture above 4500rpm, below 4500 rpm they'll aim for stoch mixture.

[robertXX]

ah no stepper or any sort of controls on miy stuff chaps .

[Pinger]

ah no stepper or any sort of controls on miy stuff chaps .

Which engine is this?
Your post reminds me of something I read in Jennings' 2-stroke book re the near impossibility of getting clean carburation across the entire speed range. He pretty much cited what you report ie, that the jetting that permits correct mixture low and high in the speed range just cannot provide enough fuel for the middle rpm range where the meat of the torque curve is. Conversely, when that is catered for, it is as rich as hell elsewhere.
Two and four strokes aint the same thing - by a big margin! - but airflow is airflow and tends to be ignorant of which engine it's destined for.