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Tony
Unregistered
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 Posted Sunday, August 8, 2010 @ 03:04 PM
Dear all,
First post so please be gentle! Am currently researching engine fitment for my newly acquired RF4D project, and a number of options lie ahead of me. I'm a professional Aircraft Engineer in the UK, having worked in the industry for 16 years from Warbird Restoration, General Aviation, Airline Line Maintenance, and now run my own Light Aircraft and Glider repair and maintenance business. I'm therefore not inexperienced in the paperwork and logistical side to alternative engine fitment even though it is pretty unpleasant.
I'm purely at the research stage at the moment, however I would welcome input form anybody who may have investigated this route previously.
I'm a larger chap, so the thought of bolting a standard 1200cc Rectimo in the front of the RF4 doesnt excite me too much, particularly as the strip it will be operating from normally requires something with a bit more grunt to maximise the take off safety factor. I'm not one for over powering small aircraft, but I do believe that more modern technology can be embraced with the older airframes, if it means spares and longevity of the powerplant is improved.
I really need the 1400cc Rectimo as a minimum, however I know of the AeroVee VW conversion that produces a monster 80Hp from 2180cc and seems to have returned a good safety record since its commercial launch in 2004.
The link here http://www.aeroconversions.com/products/aerovee/index.html gives the full low down on the unit, it weighs in slightly heavier than a standard Rectimo, and the power is considerably more, however unless someone has tried and failed before, I'd be interested in getting this fitment approved here in the UK.
So...
Has anybody bolted one of these into a Fournier and if so, was the power too much for what is a very strong airframe, or where modfications needed to the engine mounts to transmit this increase to the airframe. Does anybody have any performance data for such a fit, or even a propellor option.
It seems cost wise to be a little more than a 40 year old rectimo, however if the power increase proves not too problematic, the fact its a brand new unit designed after years of experience gleamed from the old units, it must be worth a shot at approving here in Europe.
I would welcome thoughts or comments from those on the forum.
Regards
Tony
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Jorgen
Unregistered
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Posted Sunday, August 8, 2010 @ 05:31 PM
Hi Tony,
wellcome and congratulations on your project, you will find a considerable wealth of information and Fournienthusiasm here. I take it you already read Bob Grimsteads thorough report on his engine upgrade:
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=x3udlOvUc40GewijdHqRY6qoU7&forum=13&thread=683
The AeroVee VW is certainly an interesting alternative, but I don't know of any Fournier beeing equipped with one, which doesn't rule out that there could be someone out there. The RF 5 and RF5 b's have in many instances been upgraded to the Limbach E01 2000cc which is also said to produce 80 hp, although some manufacturers disagree on the actual "grunt" it's rated at.
I'm not sure you need to worry about take off performance though, my 4 has 1400 cc and I've always felt safe on 3-400 m grass strips, unless the grass is tall or wet. I feel more that the long wings lift me up than the "grunt" of the engine, so maybe you needn't worry. There are plenty of Fourniers in the UK, try one and see for yourself before you add to much paper struggle to your project. Remember, René Fourniers Memoires are titled "Mon réve et mes combats" for a reason, and the paperwork was not his dream if you catch my drift...
May the 4's be with you/ Jörgen
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Tony
Unregistered
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Posted Sunday, August 8, 2010 @ 07:21 PM
Hi Jorgen
We've talked previously on the Cub forum in America, I believe you were rebuilding a J3 and I have the L4H. The dear L4 is still here, having moved through about 3 workshops, wings are complete, tail complete, and fuselage 95% complete. In fact all that remains is to cover the poor old girl and she'd be up and running! Slow progress though, seems to happen if I share a project! The Fournier luckily is all mine.
As for T/O performance, the strip I'm on is 600 meters with trees all around. Bob has flown his RF4 from here and its ample enough, but you wouldn't want too much of a cough outside of the field to put you in the trees. Bob is running a 1400cc I believe in his UK Fournier.
I've flown a Fournier many years ago, loved it. Has taken 7 years to get my hands on one!
My problem is that paying work has to take precedence, and with only 1800sq ft of workshop, it doenst leave too much room for the 4. The plan is though to gather and sort all the parts during the winter, and as things calm down in April next year, the hope is to bolt it all together.
I too think the AeroVee is interesting - more thoughts welcomed...
Tony
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Jorgen
Unregistered
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Posted Monday, August 9, 2010 @ 03:32 AM
Aha-
Mr Hoskins a.k.a. "FOURNIERBOY"- Even more wellcome and nice to hear from you again! Well then you know the performance envelope pretty well and also know what your getting yourself into. Rest assured all efforts to get your 4 into the air is well worth it, most on here will vouch that even after many years of flying the 4 it still evokes the "silly grin"-syndrome.
L-4H "479748" is still flying as a J-3 and I´m still trying to do some research in anticipation of the day I will have to re-cover. Nice to hear that your ambitious L-4 project is still ongoing, many Fournier pilots on here seems to fly Cubs as well (although Bob Grimstead is in the Champ-Camp and will probably comment if we post to much Cub talk).
Getting back to the AeroVee, we´ve had some discussion on their carb (AeroCarb) and I believe Ray (jb92563) is running one on his Rectimo and seems happy with it after some tuning.
May the 4´s be with you/ Jörgen
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Bob Grimstead
Unregistered
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Posted Monday, August 9, 2010 @ 06:26 AM
Hi Tony,
Bob the Grim here.
Several points arise.
First, for two years I operated my 1400cc RF4D off my 360-metre strip (see the 'where do you fly from' thread).
My main problem is it slopes downhill to the north-east, and has power and phone lines along its south west end, so on most occasions I'm taking off downhill but downwind so the margins are tight (see vid clips on YouTube, search for FournierBob).
However, last year we extended the strip to around 450 metres and now it's no problem at all, either for myself or Matt (who is a tad heavier, around 100 kg, I think --although I may be doing him a disservice here).
So 1400cc should be more than enough for you.
Point 2, G-BIIF is on a C of A, so you're NEVER going to get any power increase through the CAA, although you might do so through the BGA if you have enough clout.
Francis D at the LAA will not approve more than 1600cc in an RF4, but we've discussed the possibility of my going to 1750/1776 as I have in Australia, and he has agreed to look though my file 'next winter, when I have time'.
Apparently, according to Francis, because British Permit Fourniers now have EASA Permits, not British ones, this makes modifications much more complicated for him.
Point 3, last year I replaced my original (Barry Smith) Rectimo engine with a new one from John Maher because the oil pressure was not what it might have been.
New engine -- still pessimistic oil pressure. Bought new pressure gauge, pressure fine.
Which leads me to realise I've just wasted £5,000.
However, Bobby Warren is about to strip the original, 650-hour 1400cc Rectimo to check it out insde and replace anything that might need it, and then re-assemble it as a spare.
Meanwhile, I plan to do the same with my Aussie Fournier's 1400cc Rectimo when I get back there.
This means I shall have at least one complete, rebuilt, spare Rectimo by next spring.
I should also have a carburettor, magneto & coupling, intake manifolds, exhausts, baffles etc to make the full installation.
Fitting a proper, plated Rectimo will cause you no problems, time, effort or paperwork.
Talk to me and we can come to a deal.
Yours, Bob
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Donald
Unregistered
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Posted Monday, August 9, 2010 @ 08:24 AM
Bob, I don't want to take over Tony's thread, but if he doesn't want your 'spare' 1400 Rectimo, can we talk?
Donald
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Bob Grimstead
Unregistered
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Posted Monday, August 9, 2010 @ 10:38 AM
Yes of course, but I will let Tony reply first.
Yours, Bob
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Tony
Unregistered
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Posted Monday, August 9, 2010 @ 01:17 PM
Hi Guys
Am talking slowly with the BGA over the engine issue, it might be a simpler task but I just need to test the water to see if anyone has done anything previous. Having quickly discussed it with Jim H, with the AeroVee being a direct VW conversion, it may be fairly simple for an installation approval, but the performance is what the BGA would need to see to take it through to the EASA mod stage. Mainly the issue is as to whether more than 2 litres has been put in a 4D, and what loads this placed on the airframe.
All in the AeroVee is working out at just over £4k plus shipping to a friend in East Coast USA and then the usual methods for it crossing the atlantic, which for a brand new engine makes it about the same as a rebuilt second hand rectimo.
As for the BGA/LAA mod thing, I've had a long chat with Jim H about the highs and lows of both and have an email discussing a number of points which may be of interest to the wider audience.
Are you around thursday evening Bob for a beer if I pop over your way, have a few things to chat over, so many questions at this stage and a couple of developments! I'll drop you a text in the next few days if you are...
Rgds
T
Ps. If theres some good basis for trying for the AeroVee, I'll give it a go, if not I'll go for a Rectimo Bob.
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Jorgen
Unregistered
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Posted Monday, August 9, 2010 @ 04:17 PM
That´s the spirit, Tony!
I think we all would be excited about bolting an AeroVee to a RF 4D. Charlie Webber might have gotten closest to the increased loads on the airframe with his Revmaster 75 hp, but his example might be hard to use in communication with authorities, since he doesn´t appear to have had that much contact with them:
http://www.cfiamerica.com/Fournier_RF4D_For_Sale_N7723.html?session=lFxnmfJJUUEFuHWxeRgqDL3ZMJ
May the 4´s be with you/ Jörgen
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Bob Grimstead
Unregistered
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Posted Tuesday, August 10, 2010 @ 07:38 AM
Hi Tony,
Thursday evening's good.
Any time after 6pm, but don't make it too late, I've got another practice early the following morning.
You can see my whole, bulging file on Fournier engine power increase.
And remind me that I've got that cranked stick for you.
Yours, Bob
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jb92563
Unregistered
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Posted Thursday, August 12, 2010 @ 02:09 PM
Tony,
Yes I'm still running the Aerocarb on my Rectimo 1400cc.
After some initial trials and tribulations to get the needle set just right I now can now hand prop it no problem and it fires right up after a swing or 3.
It has behaved itself very well and I have added CHT's and soon EGT's to make use of the leaning feature that the Aerocarb provides.
It sure comes in handy when climbing at greater altitudes to keep the power working for you.
I can not see any drawbacks to the aerocarb at this point, but once I start with my aerobatic training I will likely find that having a bowl carb
will provide that little bit of extra fuel to help the engine run through some of the inverted and negative portions of the envelope.
Ray
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Bob Grimstead
Unregistered
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Posted Friday, August 13, 2010 @ 09:08 AM
Tony,
Just in case you haven't already seen this thread, there should be lots of useful information for you here... I hope.
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=cDF7QqhOq8KpkodhtUoKrmfL5d&forum=13&thread=683
Note that the performance improvement was not anything like as good as I had hoped, plus all the technical calculations required.
Yours, Bob
[Edit by Bob Grimstead on Friday, August 13, 2010 @ 09:10 AM]
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jb92563
Unregistered
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Posted Friday, August 13, 2010 @ 01:10 PM
I have often thought that a Jabiru 2200 would make a great high power source for the RF4D since it offers 80 hp at about the same weight as the Rectimo 1400cc if I recall correctly.
Cost is higher than an AeroVee but perhaps worth it to stay light and get the maximum punch by doubling the HP.
I think climb rate is going to benefit a lot more than top speed with the HP increase as the drag increases exponentially with speed.
I think you can also put composite props on a Jabiru opening up the potential to use some very efficient and adjustible props.
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Donald
Unregistered
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Posted Saturday, August 14, 2010 @ 03:00 AM
I'm no engineer but I remember reading some time ago that in, say, doubling your speed the drag will increase as the square of the increment, ie. 2^2=4, and the power required will be the cube of the increment, ie. 2^3=8. To turn that around if you double your power from 40 to 80 hp the theoretical speed increase, all else being equal, can only be around 26% max.
But there are other considerations. Weight and balance, cooling (cooling drag?), reduced ground clearance for the larger prop required to absorb the extra power, higher fuel burn bringing with it reduced range or the need for additional tankage which in turn adds weight and complication, increased induced drag and a reduction of speed.
I'm not really a fan of stuffing bigger engines into an airframe not optimised for it, but that's just my opinion. It's also not an option for me with my RF3 for there is not too much distance on my ASI between max cruise and VNE and she climbs at around 4m/sec. I guess I'm pretty happy with what René wrought.
Donald
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Bob Grimstead
Unregistered
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Posted Saturday, August 14, 2010 @ 07:17 AM
Hi Guys,
Please be aware that, after seven continuous years of Fournier use, with my continual need for more power, I have done all this investigation properly.
Both the Jabiru and the Rotax engines have much more bulk of accessories on the back.
To fit either of these engines would mean:
They have to be much further forward, needing revised engine mounts and putting the C of G outside sensible limits (compensating tail ballast puts the total weight out of limits).
or
You have to cut a much bigger hole in the firewall, ruining the structural strength.
You could probably do this with lots of structural analysis and re-design (very expensive) and physical beefing up of the firewall and its attachments to the fuselage, but then you might well be overweight again.
Never, NEVER use a composite (fiberglass or carbon fiber) propeller on a direct-drive engine. The vibration pulses cause the resin to heat up and become soft, allowing the fibers to move relative to one another, and in the blink of an eye you lose a blade and then the whole engine. That is shortly followed by tail failure (in milliseconds) and total structural failure.
There are SOME composite props which can be used with care and severe rpm limits on SOME direct-drive engines, but they are rare, and NEVER, NEVER for aerobatics.
The foregoing does not apply to Hoffmann propellers. They call their propellers 'composite' because the wooden propeller is covered in a thin layer of glassfiber, but they are basically wooden propellers, which is fine on a direct-drive engine.
Please read the FAA publication I recommended before jumping to conclusions about increasing a Fournier's power.
Yours, Bob
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jb92563
Unregistered
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Posted Monday, August 16, 2010 @ 11:38 AM
Interesting insight about the composite prop have internal stresses with the direct drive.
I always thought the danger of composite props on the direct drive was to the crank due to the higher inertia.
RevMaster do allow composite props apparently on their engines because they have increased the crank strength.
I like to be conservative though and prefer to stick with wood myself.
I am fascinated by Mr Lipps props and found a great technical description of his remarkable props in the current Issue 101 of "Contact Magazine".
He has made a great case for his designs and proved them in actual performance tests and in competition to be superior.
He has a remarkable explanation of how his multi (3) bladed props are actually more efficient and offer more speed than 2 bladed props which flies squarely in the face of previous common knowledge.
http://www.contactmagazine.com/backissu.html
[Edit by jb92563 on Monday, August 16, 2010 @ 11:41 AM]
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Skyhawk 3
Unregistered
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Posted Monday, August 16, 2010 @ 08:26 PM
Tony,
Matthew here!
In the skyhawk days we flew in 11 countries in one season using the trusted old Rectimo 1200, on our way back from somewhere in Europe we diverted to Sauer's airfield where he had put a large VW in an RF-4, it was I think very close to 2 litres may be even 2.1.
All three of us flew it and came to the same conclusion......... it was not the earth shattering increase in performance that we had hoped for. It came as a great surprise I must say.
Un be known at the time it was our last season so the R&D stopped.
Without putting a numeric or indeed a technical slant on things, I have done a lot of time in Stearmans, they were originally fitted with a Continental or Lycoming 220hp engine, which laboured. The dusters were fitted with the unbustable PW 985 producing 450hp, that spoilt the handling of the aeroplane (however it did climb very well) the sweetest by far was fitted with 300hp Lycoming.
Same goes for Super Cubs with the 180hp being quite a harsh airframe to fly compared with the 125hp. with the best being the 150hp.
I have just had the option of putting any thing from 1200cc to 1600cc in my RF-4 and working purely on what feels right gathered from flying many types and variants over the last 25years the 1400cc is for me the best.
Speak soon
Matthew
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jb92563
Unregistered
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Posted Tuesday, August 17, 2010 @ 10:34 AM
Based on a few observations and the experiments with props, carbs and engines, it seems like the RF4D benefits the most from being light weight.
Sam Mason might be the lightest pilot in an RF4D and consequently he gets spritely performance and a 700+ fpm climb rate on the 1400 engine.
His RF4D also weighs under 600 lbs empty if I recall correctly and his top speed is up near 118 mph.
The fastest RF4D I have heard of is 128 mph with the 1400 cc with a custom 8:1 compression ratio and a Culver prop, with a climb of about 600 fpm.
And as has been pointed out, doubling the HP to 80 will only yield a theoretical ~25% increase in speed, which might get you near redline for a flat out run, and that does not sound like the best thing to do in a 40 year old plane.
Even Charlie Webber with the 75 HP Revmaster mentioned to me that he felt that the increased weight spoiled the handling over the original configuration.
It all seems futile to make the RF4D into something that it was not designed to be.
Rene certainly optimized his design with little room for additional improvement as we always end up concluding.
However it is fun to tinker provided we don't get carried away.
[Edit by jb92563 on Tuesday, August 17, 2010 @ 10:36 AM]
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Donald
Unregistered
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Posted Wednesday, August 18, 2010 @ 03:23 AM
Interesting post from Matthew and, while I don't have his wide experience of flying machines, intuitively I feel his conclusion is right on the money. I also think that Ray's observation about light weight is absolutely correct and could probably be applied to most aircraft but is likely to be more significant with light aircraft like ours.
Ray's Charlie Webber hearsay is very revealing and I wonder if there are any others out there who have gone beyond the original engine block size (I don't include the 1400cc here) who would like to comment on whether, given the chance, they would do the same again.
[Edit by Donald on Wednesday, August 18, 2010 @ 03:26 AM]
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dannparks
Unregistered
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Posted Wednesday, August 18, 2010 @ 10:42 AM
The AeroVee is basically a big-bore VW with their own large main bearing/prop hub, accessory case, intake manifold, carb, and secondary ignition. You can essentially duplicate all those things with parts from other vendors. You could also build a 1600cc version which would be a little lighter. You could also build a 2180cc version with Nikasil cylinders that would be 10 lbs lighter that the stock 2180.
The main things you will be faced with are; making a new mount system that mounts the acessory case to the firewall; The stock cowl will no longer fit, so you will need one of Engenio's new cowls; the Aerovee top intake tubes and the carb placement will likely not fit under that cowl, so that will need to be reworked; the Aerovee prop hub is a few inches forward of the stock position, so you will need to modify the cowl for that. You will also likely need to build a custom exhaust.
I was faced with the same situation of wanting to replace the engine with one of slightly more power and decided to use a 1600cc from Great Plains with a custom mount and intake system. Look at the Picasa link on the bottom of this email to see how I've been progressing. Best of luck with your project.
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eugenio
Unregistered
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Posted Friday, August 20, 2010 @ 07:22 AM
If you accept not to have an electric starter you can modify your original engine without adding weight.
The engine can be easily upgraded to 1700/1800 cc with the same basic weight and using all existing accessories plus you can add a small Kubota generator always maintaining the same weight.
If you do it with new parts it's easier:
New case bored for 90 /92 or 94 nikasil cylinders. (90 is better just because you have more material left on the case and heads and cyl walls are thicker)
New (overhauled) 69mm crankshaft from GPASC with 3° tapered end, so you can use your original prop hub
New nykasil cylinders and pistons
New single port heads (1600 single port)
New (overhauled) rods
New (overhauled) rocker arms (1.1:1 ratio) and longer pushrods
Magneto support, magneto, carburetor and manifold can be reused without problem, you only need to change the manifold flange for the new heads.
You add a small Kubota generators and you will have an engine with 50% more power at the same weight (the increase from the generator is compensated by the saved weight from the nikasil cylinders.
Next step is to find the correct propeller.
Now with a 69 crank and 90 nikasil cyl I have a top speed of 210 Km/h with 3400 RPM and a rate of climb of 4 m/s at 110 Km/h
I guess this is the best option you can obtain for a RF4, sincerely I think a 2000 or bigger engine is not the best choice unless you want 8m/s of climb and a thirsty engine for the cruise.
Eugenio
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Bob Grimstead
Unregistered
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Posted Saturday, August 21, 2010 @ 05:59 PM
Hi Guys,
Like pretty much everybody else, I now know 1400cc is the best for an RF4.
I reckon I wasted my money and a huge amount of time on the nikasil 1750cc motor that's now in my blue one.
(See my separate post).
Yours, Bob
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Donald
Unregistered
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Posted Sunday, August 22, 2010 @ 02:17 AM
Hi Bob,
That's a disappointing conclusion to arrive at yet you're prepared to sell your 'spare' 1400cc Rectimo? At the risk of stating the obvious can you not swap it into the blue 4 and sell the 1750?
Donald
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Bob Grimstead
Unregistered
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Posted Monday, August 23, 2010 @ 07:18 AM
Hi Donald,
Remember, I have two Fourniers, separated by 10,000 miles, and each has two engines.
I recently put a new John Maher 1400 in my British (red) one, because I was concerned about the original (red) Rectimo's comparatively low oil pressure, and despite having replaced its whole top end.
Then the new John Maher (black) engine exhibited low oil pressure.
I replaced the oil pressure gauge, and bingo, the oil pressure's fine, so now I know there's nothing wrong with the original red Rectimo.
Bobby Warren (Skyhawks engineer and rebuilder of Matt's excellent Rectimo) will overhaul it for us as a spare this winter, but to speed the return of Tony's G-BIIF into the air, I would be happy to sell it to him.
Over in Australia, I've replaced my blue Fournier's grey Rectimo with an Australian Aeropower 1750, using 90mm nikasil cylinders.
It does not exhibit much better performance, it is physically bigger, it needed a new carburettor, new intakes and exhausts (which are burning the cowlings), it uses more fuel and it vibrates like a Harley Davidson, despite having fully balanced components and propeller.
I am not selling my original (grey) Australian Rectimo, and will probably overhaul that with the help of local Volkswagen expert Mike Munninger of Aeropower Engines (who built my 1750).
In a year or so, after having fully broken in that Aeroppower engine, I will make a decision as to whether to sell the original (grey) Rectimo, or to re-fit it to my blue Fournier and sell the Aeropower 1750.
Watch this space.
Yours, Bob
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eugenio
Unregistered
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Posted Monday, August 23, 2010 @ 02:11 PM
Maybe something has not been blueprinted if you say that about the 1750. And I add that you wasted lot of money trying to modify everything, while there was nothing to modify...
Mine with 90mm Nycasil cylinders (a set from a Limbach 2000) with the same carburator and all original manifold and mag support, (only new head flanges for the manifold) run smoother than any other engine I tried before (1200, 1400 and 1600) has a lower fuel consumption (at same speed) and much better performances.
Eugenio
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Bob Grimstead
Unregistered
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Posted Tuesday, August 24, 2010 @ 09:30 AM
Wow Eugenio, I thought the vibration was because of the bigger pistons etc.
The engine was blueprinted and the crankshaft was dynamically balanced, plus the propeller was new and statically balanced and it has a new spinner, so I must investigate further.
The reason for the new mainfolds etc was that I had to use twin-port heads, because I could not find any new single-port heads in Australia. Maybe they are available in Europe, but John Maher (VW expert, Scotland) also said he could not find them new, only old, used.
I think maybe the poor performance is partly due to a lot of internal friction. The propeller is quite stiff to move. I have only made two flights, so maybe once the bearings have eased a little and the piston rings are properly broken-in, the performance will improve. I do hope so. The engine builder told me that nikasil cylinders take longer to break-in than normal piston rings/cylinders -- maybe 50 flying hours -- mine are also 90mm cylinders from a Lmbach 2000.
I am currently running the original Zenith carburetor, but with a 1.40mm main jet and drilled-out internal fuel passages to allow 20 litres per hour fuel flow, which is what it burns at full throttle. I established the mixture is correct on full-throttle ground runs using an NGK AFX fuel/air ratio exhaust sensor (the Limbach 1700 with Zenith 28RXZ carb uses a 1.50mm main jet). Maybe if you get improved comsumption, you are running a little lean?
Yours, Bob
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eugenio
Unregistered
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Posted Tuesday, August 24, 2010 @ 03:22 PM
You must check in the US for the single port 1600 heads, there's where I found them.
I did not do all the check like you did, I first used the 1.30 main jet I had on the 1600, then when I found I had high CHT (not too high, just high) I opened the jet to 1.35 so now I have fine readings always in the green arc, also in steep climb and 50°F below yellow arc in cruise.
All people with the 1700 (the L1700) claims to have a fuel consumption about 10 liters at 150 Km/h; Usually I run a little faster, but at 150 Km/h I have less than 2500 rpm and at 2700 rpm I cruise at 170 Km/h with about 12 l/h of consumption. I don't think that with the 1400 at the same speed you have a smaller fuel burn.
Vibrations can also come from the spinner or even from the propeller, also if it is statically balanced. Try without the spinner, spinner dome and another propeller. You can also chech dynamic balance of the entire engine to find out the problem.
It is very strange that the prop's stiff to move, it should not, unless you have too small clearance in the bearings or end play, or maybe depends on the modification you did with the thrust bearing. Does the crankshaft do clunk-clunk when you pull the prop? if not probably you have not enough end play.
Nykasil cylinders take longer to seat, but this does not affect stiffness.
I never found which size of main jet uses the L1700, but 1.5 is the needle valve seat hole size that in the 28RXZ is 2.5 due to the lack of fuel pump.
ciao
Eugenio
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Tony
Unregistered
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Posted Wednesday, August 25, 2010 @ 04:17 PM
Hi Bob et al
In light of the various comments here and with a few other questions that about the Aerovee that have popped up during the thought process, I think I will go with Bob's Rectimo 1400. Whats your timescale for getting rid Bob, I'm probably in a position to go for it during this winter when all my regulars come back for their annuals...
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Bob Grimstead
Unregistered
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Posted Wednesday, August 25, 2010 @ 04:21 PM
Thank you very much for all that information Eugenio.
When I return to Australia, I will investigate further, and tell you all what I find.
Meanwhile, the main jet for a Limbach 1700E engien with the Zenith 28RXZ carburetor is 1.50mm.
Go to http://www.fournieruk.com/
Click on the Technical tab on the left
Click on Manuals (at the top, second from the left)
Click on Limbach 1700E engine manual.
Go to page 8, section 3.2.2, line 14 says Main Jet 1.5omm
That document does not give the fuel consumption with this carburetor and jet, but the original RF5 manual using that engine quotes fuel consumptions as:
110 mph/3400rpm = 14lph, 100mph/3200rpm = 12lph, 87mph/2800rpm = 10lph.
You can see my fuel consumption on my page of 1750cc engine information.
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=so6jxl4kToHvelis1WZUgKY7ko&forum=13&thread=683&page=1#17
I used 24 litres in one two-hour flight.
That is a very rough average 12 litre per hour consumption, but this was not steady cruising.
I suggest that, if your are using a smaller main jet Eugenio, or burning less fuel than that, you may be running a little lean.
Thank you for all your advice, and thank you, Mike Millar, Dave Bland, Collin, Steve and everybody for making all this information available to the whole Fournier world.
Yours, Bob
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eugenio
Unregistered
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Posted Wednesday, August 25, 2010 @ 05:31 PM
Thanks for your input about the Limbach 1700 Manual, I was not able to find it; you're right the main jet is 1.5, but I can assure that I found every size of main jet on Rectimos. On one of the last, a 1200 overhauled by Sauer some 10 years ago, fitted with 83 mm cylinders (so it's a 1400) I found the main jet sized 1.20, and was working fine since the overhaul (more than 1000 hrs ago), so I think that the main jet size is important, but not so much. With the 1.30 mine had too high head temps, but with the 1.35 temps are ok, so I think now it is fine. Maybe also the whole cooling baffles installation and oil cooler can affect the heads cooling, not only the more or less lean mixture. Also the compression ratio can be important, mine is between 7.5 and 8.
Also the propeller can make the difference, there are propellers that cools the engine better than others (with more or less the same performance) and I can assure it is not easy to find the right one. By the way mine is a copy of an MT 133/100.
Thanks for your suggestions
ciao
Eugenio
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