I was wondering if anybody had any pictures from a cilinder made up of several modular pieces. (for dyno testing purposes). I believe Jan (or Frits) posted pictures a while back, but I can't find them anymore. If memory serves me correct the transfer ports and exhaust duct were seperate blocks that could be exchanged.
For testing purposes I would like to use a pressed in cast iron sleeve because it is easy (and cheap) to modify. I know these are not ideal in a watercooled cilinder. I was wondering if this could be improved by milling away the aluminum above the exhaust port (full curcumference) so the top 20mm of the liner under the head is exposed to the cooling fluid.
For testing purposes I would like to use a pressed in cast iron sleeve because it is easy (and cheap) to modify. I know these are not ideal in a watercooled cilinder. I was wondering if this could be improved by milling away the aluminum above the exhaust port (full curcumference) so the top 20mm of the liner under the head is exposed to the cooling fluid.
wouldn't that nescesitate the use of a seal between sleeve and cylinder ?
wouldn't that nescesitate the use of a seal between sleeve and cylinder ?
I also think the remaining press fit would not be up to the task of holding the cooling fluid out of the engine (or exhaust gas out of the cooling fluid). I have had some good experiences with ekraz o-rings (working temp of 300°c). So it would probably be neccesary to put an oring groove on the outside of the liner so it seals the cooling water from the rest of the engine (much like a detroit diesel liner).
I was wondering if anybody had any pictures from a cilinder made up of several modular pieces. (for dyno testing purposes). I believe Jan (or Frits) posted pictures a while back, but I can't find them anymore. If memory serves me correct the transfer ports and exhaust duct were seperate blocks that could be exchanged.
Here you are Bjorn. These modular pieces started life as normal cylinders (Garelli 250 cc V-twin, about 1984) that were modified so they could easily be fitted one into the other and taken apart again for modification. They were not meant to be used on a running engine on the dyno, but for flow testing on a flow bench.
I was wondering if anybody had any pictures from a cilinder made up of several modular pieces. (for dyno testing purposes). I believe Jan (or Frits) posted pictures a while back, but I can't find them anymore. If memory serves me correct the transfer ports and exhaust duct were seperate blocks that could be exchanged.
For testing purposes I would like to use a pressed in cast iron sleeve because it is easy (and cheap) to modify. I know these are not ideal in a watercooled cilinder. I was wondering if this could be improved by milling away the aluminum above the exhaust port (full curcumference) so the top 20mm of the liner under the head is exposed to the cooling fluid.
"I am also going back to iron sleeves. Nikasil is more of a pain than I think it is worth. I may prove myself wrong, but I am going with it.
The problem with Nikasil is if you seize it ruins it which is expensive and takes a month to have re-done. But the worst part is every time it has to be replated, the nitric acid eats all of the alloying elements out of the aluminum. Last years engine is toast. The threads are all gone. Anything that used to be a press fit is now loose. It may make more power not to have the residual heat from the iron heating up the intake, but it comes at a way too high of cost...for me.
The bike is all ready to go for this year. It makes more power than I ever dreamed. But the salt may be a thing of the past. Speed week was canceled and the Bonneville Motorcycle Speed Trials right after. World of Speed has not been canceled as of yet, but all reports make it look not promising. I will be there if it is a go.
Thanks for the replies. Some food for thought this week.
When I arrive at something tangible I will post some pics here.
Frits, you talked in the past about a structurally thermal sound engine being watercooled with onepiece cilinder (nikasil) and a high flow waterpump. Do you believe exposing a cast iron liner as much as possible to the cooling fluid would help, or will it be the proverbial (in Dutch anyways) 'droplet on a hot plate'?
Frits, you talked in the past about a structurally thermal sound engine being watercooled with onepiece cilinder (nikasil) and a high flow waterpump. Do you believe exposing a cast iron liner as much as possible to the cooling fluid would help, or will it be the proverbial (in Dutch anyways) 'droplet on a hot plate'?
It will certainly help, compared to a conventional shrunk-in or pressed-in liner but I think it will not be good enough once your engine starts making real power.
Heat transport through the iron is not nearly as good as through aluminium, only a small part of the iron liner will be in direct contact with the water, and the transition to the surrounding aluminium will be a thermal barrier for the remainder of the liner, you'll need O-ring sealing above and below the wet part of the liner, a cylinder with any shrunk-in or pressed-in liner, even if it is a light-alloy liner, is structurally weaker than an integral cylinder, the cut-away volume of aluminium will weaken the cylinder even more, and a hard-chrome plated piston ring in an iron liner will cause rapid wear unless you give that liner a nikasil surface; but then why opt for a liner at all?
It will certainly help, compared to a conventional shrunk-in or pressed-in liner but I think it will not be good enough once your engine starts making real power.
Heat transport through the iron is not nearly as good as through aluminium, only a small part of the iron liner will be in direct contact with the water, and the transition to the surrounding aluminium will be a thermal barrier for the remainder of the liner, you'll need O-ring sealing above and below the wet part of the liner, a cylinder with any shrunk-in or pressed-in liner, even if it is a light-alloy liner, is structurally weaker than an integral cylinder, the cut-away volume of aluminium will weaken the cylinder even more, and a hard-chrome plated piston ring in an iron liner will cause rapid wear unless you give that liner a nikasil surface; but then why opt for a liner at all?
Hi Frits, I am having great difficulties formulating a reply when you answer a question.
Bottom line for me would be costs. I can machine everything at home, make changes and test it the same day on an engine dyno. (It would be nice for testing purposes if you can bolt on a different exhaust duct.) Afterwards the best design can then be transfered to a nikasil cilinder.
This brings me to another question
I am in the proces of building an engine dyno/test stand. The dyno brake is a hydraulic pump suspended on bearings with a reaction arm connected to a load cell. Did anyone here build their own dyno/have any experiences with this matter?
That modular CNC machined RD400 cylinder was analysed /designed in EngMod and was beautiful work.
The good thing about optimizing everything in a well constructed sim first, was that it made exactly the power as predicted, no experimental changes were needed at all.
He solved all the issues with sealing the liner and it ran very hard as you can see from the dyno graph.
If you are serious about doing the huge amount of machine work then PM me and I can put you in touch.
It hasnt run on the salt yet to my knowledge due to water issues ruining the speed week.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
Back story so far:- Finished product, narrowest part of the duct is 1.5 times the bore diameter from the exhaust port window, it looks the business.
Blue = 75% nozzle of total port window, but with a dam blocking part of it. So basically 100% of the blowdown. Tonight's efforts, Red line = 75% nozzle of the open part of the exhaust port. Or basically 75% of the blowdown. The 75% restriction is 1.5 times the bore diameter downstream from the piston.
It is looking like the nozzle should be 75% of the total exhaust port window without the dam.
At 13.6 rwhp this is Team ESE's best RG50 powered bike. It was prepared by Chambers for Av. The engine development is fairly conventional and its performance is good by New Zealands F5 standards. The best F5 bike I have heard talk of, is a Derbi with mid 14 rwhp.
The Team went to a lot of trouble to build a better RG50 engine, full reed inlet system, toridal head insert and exhaust port dam with exhaust port duct nozzle, bigger A transfers and Boost ports.
Top Blue line is Chambers best cylinder, currently in bike 21.
Green is the new cylinder we had high hopes for with big case reeds, toridal head, but with no exhaust port dam or exhaust duct nozzle yet.
Middle Blue line is the new cylinder with exhaust port dam added and a 90% of blowdown nozzle.
Red, our latest effort, 75% of blowdown nozzle.
We recon that if we keep working diligently by the end of the week we will have halved the power we started with.
And by the end of the year, will possibly have disappeared into a black hole. ...
Next move is to remove the dam and start working backwards undoing all those good ideas.
Sit down with a nice wine and contemplate "the first concept of superior principle is always defeated by the perfected example of established practice"
I found a std head under some stuff the other day if you have an actual need for it its yours.
Thanks but I think the problem is not going to be the head, I suspect the reed valve setup myself.
Originally Posted by Grumph
Sit down with a nice wine and contemplate "the first concept of superior principle is always defeated by the perfected example of established practice"
I am in the proces of building an engine dyno/test stand. The dyno brake is a hydraulic pump suspended on bearings with a reaction arm connected to a load cell. Did anyone here build their own dyno/have any experiences with this matter?
That sounds a lot like a water brake. My first dyno was a Heenan & Froude water brake. In its original form it was totally unsuitable for two-stroke development.
The torque curve of the engines was much steeper than the brake's torque curve so either the engine torque was lower than the brake's and the engine would stall,
or the engine torque was higher than the brake's and the revs would shoot right up to the engine's maximum rpm.
I more or less solved that by doubling the brake's revs and tripling the water pressure in the system. But the high pressure led to the next problem: the hoses that connected the brake body to the feed pump, tried to straighten themselves, exerting an unknown amount of extra torque on the brake body and hence on the scales (no load cells in those days).
Another consideration: building an inertia dyno is always simpler and cheaper than building a braked dyno and an inertia dyno is much more useful for competition engine development because you can choose the gearing such that the rate of engine acceleration on the dyno equals that of the same engine on the race track.
This way the all-important temperature rise of the exhaust pipe will match the real circumstances; that is impossible to achieve with a brake.
And before someone tells you it can be done with a step-test: no it can't. A step-test requires a brake with a sophisticated controller and all it can do is register a certain rpm and a certain torque value, and then let the engine accelerate to the next rpm-step in a pre-set amount of time. If the engine happens to pass through a torque dip, the controller will ease off some braking in order to get to that next rpm within the pre-set time.
Reality is not so kind: if an engine on the track goes through a torque dip, the rate of acceleration will drop, it will take more time to get through the dip, and sometimes carburation behaves so bad that the engine won't climb out of the dip at all. An inertia dyno will relentlessly reveal this; a brake won't.
Very true Grumph. It means that each time the result of a modification is bad, you will have to fight the general opinion that the modification itself was bad.
And as the general usually holds the purse, this can be lethal for research. I've experienced it more times than I care to remember.
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Originally Posted by bjorn.clauw.1
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