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How to make it go faster
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peter scott



Joined: 18 Dec 2007
Posts: 6044
Location: Edinburgh

PostPosted: Mon Dec 17, 2018 9:46 am    Post subject: Reply with quote

47Jag wrote:
The originals posts request was to create a 100mph Aero Minx. Assuming the ability to achieve 70mph with the current state of tune. Im guessing that it wont be pulling more than 4500rpm at that speed. Extrapolate that to 100mph it would have to be capable of 6500rpm.

Art


I assumed the 100 mph target was just an indication of the power increase required. If it currently reaches 70 mph then it probably requires at least double the current power to get anywhere near 100 mph.

If 1935Hillman is serious about reaching the ton then as Art points out it will need to run at 6500 rpm on current gearing. The engine is unlikely to be properly balanced at present so balancing will be essential or it will be wasting its power trying to shake itself to bits.

Peter
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ukdave2002



Joined: 23 Nov 2007
Posts: 3412
Location: South Cheshire

PostPosted: Mon Dec 17, 2018 10:01 am    Post subject: Reply with quote

peter scott wrote:
47Jag wrote:
The originals posts request was to create a 100mph Aero Minx. Assuming the ability to achieve 70mph with the current state of tune. Im guessing that it wont be pulling more than 4500rpm at that speed. Extrapolate that to 100mph it would have to be capable of 6500rpm.

Art


I assumed the 100 mph target was just an indication of the power increase required. If it currently reaches 70 mph then it probably requires at least double the current power to get anywhere near 100 mph.

If 1935Hillman is serious about reaching the ton then as Art points out it will need to run at 6500 rpm on current gearing. The engine is unlikely to be properly balanced at present so balancing will be essential or it will be wasting its power trying to shake itself to bits.

Peter


Its also about drag:

The power needed to push an object through a fluid increases as the cube of the velocity.

E.G. a car traveling at 50 mph may require only 10 horsepower to overcome aerodynamic drag, but that same car at 100 mph requires 80 hp .

With a doubling of speed the drag (force) quadruples. Exerting 4 times the force over a fixed distance produces 4 times as much work.

At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, 4 times the work done in half the time requires 8 times the power.

Dave
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peter scott



Joined: 18 Dec 2007
Posts: 6044
Location: Edinburgh

PostPosted: Tue Dec 18, 2018 9:55 am    Post subject: Reply with quote

Just so. Look at the bottom left chart. Windage is better with more modern cars but 1930s cars have significant drag.


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alastairq



Joined: 14 Oct 2016
Posts: 1166
Location: East Yorkshire

PostPosted: Tue Dec 18, 2018 10:44 am    Post subject: Reply with quote

https://scontent.fman3-1.fna.fbcdn.net/v/t1.0-9/12565620_10156456656845051_6747990116007623791_n.jpg?_nc_cat=103&_nc_ht=scontent.fman3-1.fna&oh=f0504775c2574cafc01f6d8871130d6b&oe=5CA599DB
An image of the airflow over a typical Dellow, done by a relative of a member , who works in aerodynamics....no wonder my hair is the way it is!!
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Dellow Mk2, 1951 built, reg 1952.
Ford Mustang coupe, 1967, 6 cylinder auto.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ford Pop chassis, Ashley 1172 bodyshell, in pieces.
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1935Hillman



Joined: 06 Apr 2010
Posts: 257
Location: Hampshire

PostPosted: Thu Jan 10, 2019 8:05 pm    Post subject: Reply with quote

A number of issues have kept me away from the forum for some weeks but I am thrilled to see so many contributions to my question, thank you all very much. Alastairq your very thorough reply is particularly interesting but also the comments that it brought forth. They all warrant re-reading which I will do over the weekend.
Just to say for now that my tourer goes pretty well due to the addition of a 11/2 downdraft SU that was tuned on a rolling road by a very capable chap in Yeovil who has now moved I believe. Certainly the rear axle ratio is a known handicap having only been 'improved' from the standard saloon by Hillman from 5.33 : 1 to 5.0 : 1. A better diff would be a good start and there must be lots of options out there. I did speak to a firm about making a crown wheel and pinion but the cost saw prohibitive.Suggestions ?
Back in the day a number of heavily modified Aeros achieved no little success with among other things the addition of a Zoller blower just as some have suggested.
I have all the bits to assemble one more Aero and may start this year some time so will perhaps try to get together with an experienced sidevalve tuner to see what can be achieved.
Thank you all so much again
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alastairq



Joined: 14 Oct 2016
Posts: 1166
Location: East Yorkshire

PostPosted: Thu Jan 10, 2019 8:31 pm    Post subject: Reply with quote

Am I right in thinking the track of your car [rear] is around 4 foot?

If so, then maybe using a much more modern rear axle might sort some of the final drive ratio issues?
For example, Ford Anglia 105E?

The differential may be fine..it's the final drive ratio [crown wheel & pinion] that can be changed....

As an example, I considered using a Suzuki Supercarry van rear axle as a modern replacement for something like the Ford Pop [103E]....axle......or other sub-4 foot track axles...the Suparcarry axle being around 3 foot 9 inches. It also has a 5.0:1 final drive ratio....which may not be helpful if the engine cannot rev high enough. The idea was taken further in the Liege kitcar, to replace the Reliant axle [my cannon, which has a Suzuki axle [replaced an Austin 8 axle]....was measured on an Edinburgh trial many years ago, during a break in proceedings] hen there will be hub issues...matching the hub that is with the axle, to the Hillman wheels?
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Dellow Mk2, 1951 built, reg 1952.
Ford Mustang coupe, 1967, 6 cylinder auto.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
----------------------------------------------
Ford Pop chassis, Ashley 1172 bodyshell, in pieces.
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colwyn500



Joined: 21 Oct 2012
Posts: 1731
Location: Nairn, Scotland

PostPosted: Fri Jan 11, 2019 8:10 pm    Post subject: Reply with quote

A slightly different crownwheel/pinion can make a great difference. I changed for a bigger engine in my Fiat 500 which increased the maximum power output by 30%. So I was running out of gears before I ran out of puff. A seemingly minor change from 8/39 to 9/39 in tooth ratio has increased speed by approximately 8% but kept the gearchange intervals and overall driveability the same.
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1935Hillman



Joined: 06 Apr 2010
Posts: 257
Location: Hampshire

PostPosted: Tue Jan 15, 2019 1:51 pm    Post subject: Reply with quote

The crown wheel and pinion idea would surely be a relatively simple conversion. I should look into what might actually physically fit within the existing casing. The wheel must be the (relatively) easy bit but the pinion might prove more tricky. 4:1 would be nice.
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Ray White



Joined: 02 Dec 2014
Posts: 2923
Location: Derby

PostPosted: Tue Jan 15, 2019 3:27 pm    Post subject: Reply with quote

Is this car to be used for competition? If it is to be used for racing I can appreciate the quest for speed but if not then I fail to see the point of a 100 mph Hillman Minx. Confused
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colwyn500



Joined: 21 Oct 2012
Posts: 1731
Location: Nairn, Scotland

PostPosted: Wed Jan 16, 2019 9:43 am    Post subject: Reply with quote

Ray White wrote:
Is this car to be used for competition? If it is to be used for racing I can appreciate the quest for speed but if not then I fail to see the point of a 100 mph Hillman Minx. Confused


Some people have suggested that of my conversion but the target was to have a more relaxed experience for the engine and for me at a decent cruising speed. Even when we use the minor roads which are more suited to our cars, it's impossible to avoid the fact that most routes have been straightened and gradients have been eased since the cars were built. Whilst I enjoy tootling along at a modest speed (why else would I have bought a two-cylinder car?) Smile it's good to be able to show a decent pair of heels when the route gets boring or when I get caught up with a jam of faster cars.
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alastairq



Joined: 14 Oct 2016
Posts: 1166
Location: East Yorkshire

PostPosted: Wed Jan 16, 2019 10:30 am    Post subject: Reply with quote

Cars may be faster...but the drivers haven't been 'tuned'....

If they want to go faster, then they can overtake!
It won't be any different if we were driving a < 3.5 tonne van. Or a lorry. Or a bus. Or a mini bus. Or a series Land Rover.
All of which have different speed limits. [Whether imposed by Law, or imposed by capability.]

The fact that an old car doesn't 'look' like a tranny van is irrelevant....

In my view, I feel it is fine to 'tune' an old car...making use of the advances in technology to make it run better, more efficiently.

But I don't believe in altering them to the extent of changing their dynamics...their 'characteristics'...otherwise, [for me] what is the point?
_________________
Dellow Mk2, 1951 built, reg 1952.
Ford Mustang coupe, 1967, 6 cylinder auto.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
----------------------------------------------
Ford Pop chassis, Ashley 1172 bodyshell, in pieces.
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Ray White



Joined: 02 Dec 2014
Posts: 2923
Location: Derby

PostPosted: Wed Jan 16, 2019 11:32 am    Post subject: Reply with quote

alastairq wrote:

In my view, I feel it is fine to 'tune' an old car...making use of the advances in technology to make it run better, more efficiently.

But I don't believe in altering them to the extent of changing their dynamics...their 'characteristics'...otherwise, [for me] what is the point?


I couldn't agree more. This is why I suggested fitting a vacuum advance to the distributor as considerable benefits can be obtained by advancing the ignition at lower throttle settings; particularly with the "slow burn" problems associated with modern "ethanol" petrol.
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colwyn500



Joined: 21 Oct 2012
Posts: 1731
Location: Nairn, Scotland

PostPosted: Wed Jan 16, 2019 11:53 am    Post subject: Reply with quote

alastairq wrote:


But I don't believe in altering them to the extent of changing their dynamics...their 'characteristics'...otherwise, [for me] what is the point?


I agree with that; I get the impression that some younger owners of "classic" cars are so distant from the original experience of older vehicles on the road that they see no contradiction in completely altering the appearance and the performance so that it is closer to their experience of contemporary cars.

When discussing my little Fiat, a lot of people are very keen to upgrade the seating, add lots of gauges, lower the suspension, change steering-boxes for steering-racks, install seat-belts front and rear etc. etc. You can even retrofit central-locking to this vehicle which was first built in 1957!

It frustrates me that they miss the point of what the car represents but was it not ever the same? Shocked
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Ray White



Joined: 02 Dec 2014
Posts: 2923
Location: Derby

PostPosted: Wed Jan 16, 2019 12:39 pm    Post subject: Reply with quote

colwyn500 wrote:


It frustrates me that they miss the point of what the car represents but was it not ever the same? Shocked


Yes, of course the young have always liked to "hot up" their cars (if you can excuse the incorrect grammar) but the difference is that modern quick cars are available to them now; a situation that was not often the case in the past and which led to the building of specials etc.

I suggest your frustration is born from the knowledge that original examples of your car are now becoming rare and the practise of modification - especially doing things that cannot be reversed - is unsustainable.
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badhuis



Joined: 20 Aug 2008
Posts: 1051
Location: Netherlands

PostPosted: Wed Jan 16, 2019 12:51 pm    Post subject: Reply with quote

colwyn500 wrote:
You can even retrofit central-locking to this vehicle which was first built in 1957!

I agree for a narrow two door classic (just bend over a little to unlock the other door) it is a bit much but usually central locking in a classic is a good example of a proper useful addition.

1. it can be installed completely hidden
2. no more fumbling with your tiny key on the door and not having to use the fragile door key lock
3. comfortable and convenient - especially with a four door car

Reason #2 (#1 as well) was the main argument for me, I am installing a set into my Jensen. It works well, I have installed CL to 3 other classics years ago.
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