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MG MGA - Extra Power on the Cheap...

Read a recent thread about boring out a 1600cc engine and after recent threads and results I propose following as an extraordinarily cheap alternative ( $80 approx) to get the power of an 1800cc engine from a 1600cc engine..
....Rig up a bilge blower to blast cool air over your air filter intakes..see recent thread . When driving the filters are probably seeing 155f...if you could get this down to 110f ...and this seems practical..then extra power of up to approx 8% percent available 1600cc now equiv. to 1730 cc.
...Install stub stacks as per recent threads....extra 5% power on top of above 1816cc.

...seems too easy and I have been a wee bit simplistic on the above ..but have I got something wrong ?!!!!
Neil Ferguson

Good thinking! Get a job as a huckster!
Add it all up and the car transcends time and gas pours out of the constant self filling tank!

I have seen no evidence for reduced carb temps under road conditions over 25mph, and don't expect any, so aside from the first 100 feet, my 1% will beat your 8%.
If there is any advantage at road speed, I'd be glad to hear of it, but I would then alter some ducts or deflectors or something and save the parasitic drag from feeding the blower.

1% of all-up weight is about 2 inches belt size, how's your pants fit? A hamburger a week less costs $80 more in your pocket pretty quick! But all that cash adds weight...

FR Millmore

Then you could leave the spare tyre out; only half fill the tank; fit a sports windscreen and remove the how about a bit of water injection from a squeezy bottle?

Steve Gyles

Actually, washer pump water injection is cool (sorry).
Better yet, spray the water in the airstream from the duct blower, in a venturi nozzle, refrigeration cools the air and the carbs breathe it = one rock two bird = cooler yet.

We up to 25% power boost and free gas yet?

FR Millmore

oh ye poor souls of little faith and limited horizons.......I hope today to get some info on driving at distances beyond the length of Fletchers tongue and at speeds greater than the snails pace of the minds of both of you wee ones....
Neil Ferguson

From an unsophisticated Ozzie in the land down under and to the duet of Scoffers from the Northern Polluted Hemisphere...
I performed a series of tests today..
1) Rigged up water injection system to try out sincere suggestions from scoffers above..useless
2) Threw out spare tyre ..microscopic affect.
3) Stuffed hamburger down front of trousers to join ferret......belt got greasy and needed to change jocks.. No practical benefit.
Dissappointed in your advice..not practical...possibly just bilge.!!

Then tried my suggestion ..
Gauge fitted at position shown on pic. below .
Grandson, aged 9, fitted into pax seat as independent observer/inspector/corroborator and to read out temp. meter readings.
He has written up a separate 30 page report on following tests.

Ambient 17.5c (63.5F)

Test 1
Drove at 100kph , bilge fan off, until probe temp stabilised at 42c (107f)
Turned on fan and temp dropped almost and stabilised at 32c (89.6f) after about 1 min ..

Test 2..consistency test.
Drove at 100kph ,bilge fan off, .Temp stabilised at 42c (107f)
Turned on fan...temp dropped to 33c (91.4f)

Test 3 ..Low speed test of Fletcher absolute conviction statement below...
Drove at 50kph (31.25kph i.e. greater than 25mph)
Temp without fan...53c (127.4f)
Temp with fan ...43c (109.4f).

Fan seems to be able to achieve an approx 10c (18f) reduction which correlates to about 3.2% more mols of air going into carb.. and I think that is a magnificent result for a gross outlay of about $25.
At the gross risk of Scoffers United above suggesting I now try making a perpetual motion mga or similar ....and extrapolating ...
Basics....I have a Judson and my air filter is 46cm from the fan duct outlet. The equivalent average distance for a pair of standard mga carb filters is about 25cm .
Using the Holgren-Girkin-Burke inverse law of gas and temp mixing from a fixed point ( the duct ) and allowing for the very prominent affect of air being drawn in from the body vent ( which faces the wrong way!) and reducing my air filter temp ( as evidenced by the test 1/2 results and test 3 differences) dare I postulate that the temp drop for the bog standard carb config would be more than above 10c.....

Neil Ferguson

Neil, Oops - Sorry mate, I hadn't seen this thread of yours before replying to your other 'blower' response. Now I see where you're coming from...
P N Tipping


Surprised the water injection was so quickly dismissed:

Interesting that your temperature drops showed 10 degrees. My rough and ready vacuum test with a lower volume shift managed a 5 degree drop. When I get back from my hols I am going to get a similar pump and try it in both positions. Should be an interesting comparison.

Steve (Scoffer2)
Steve Gyles

Whilst I have a lot of sympathy with FRM I do know the merits of cooling the inlet charge to our engines, However I have tested ram pipes on a number of occassions and have yet to witness any benefits apart from the throaty sound that is generated. :) But everyone to their own as we say.

I have an intercooler connected to my turbo installation and it works very well, The only issue I have got with Neil's calculation is that the temperature of his input charge will be generated after the compressor I would imagine, how much affect the inlet temperature to the blower will have as a percentage I wouldn't want to speculate but it must have some effect?
Bob Turbo Midget England

Bob...agree with the direction of your comment . The full 3.2% is unlike ly to translate to power as the affects on the air as it passes through the blowers, manifolds , valves etc will moderate the benefit...but lower air temp is a big plus and I would guess most will translate to umph..
Neil Ferguson

Thinking about running a duct from the fan outlet down past the Judson to adjacent to carb to test to see just how low the bilge fan can lower air temp......a poor mans air box. I believe it could generate another 10 c reduction..but not sure I would like the look of it...
Another improvement would be some change to the air vent scoop inside of the vent to improve air flow inwards from this source.....This vent seems to have an major increasing benefit with speed ....
Neil Ferguson


I'm not sure where you will find the space to do that, but delivering cold air to the Judson would add a few HP.....
dominic clancy

All Hail Ozzy-Man-Dios!!

Truly thou art cooler than me!

Ever picky, I say:
"I have seen no evidence for reduced carb temps under road conditions over 25mph, and don't expect any, "
>>So now I am presented with some evidence of such improvement; extend and confirm por favor. Can you get going a bit faster and report temps there? Thanks! Twill need to be another conspirator, as you have mucked up the flows patterns with your quaint Huff & Puff as opposed to the usual Proper High Level SUckers.
Could I count and charge for the number of times I have been kicked in the ass by stuff not expected, I would be a rich man. Sometimes the kick is welcome and even kinky fun. (not as kinky as feeding the ferret with a hamburger I suggested you not purchase!)

"...don't expect any...If there is any advantage at road speed, I'd be glad to hear of it, "
>>And indeed I am, and I thank thee again, whilst again noting that the geometry/flow (feng shui?) of your engine house is a bit off the accepted community standard.
"Fletcher absolute conviction statement "
>>Bad reading on your part Ozzy.

"but I would then alter some ducts or deflectors or something and save the parasitic drag from feeding the blower."
Random: 4" blower might be better than 3" (if this holds up...)
Even just blocking off the cowl air grille might create a greater low pressure zone under bonnet to suck more cool air from the front at speed, at the risk of making low speed/stationary cookery inevitable if the blower fails. As we say here - "throw another burger on the grille".
Or ducting the blower air through a venturi extractor with the low pressure connection to the cowl vent would suck yet more and cooler air from the vent, and then cool it further as it expands out the venturi. Note that there are whole companies and little industries that build assorted devices to do just this.

Note that Mr Gyles may have an entirely different experience, as he not only has two SUckers (dat's kinky, and he tried a third!), but also a modified screen possibly causing yet more deviant behavior.

About that alleged "water injection":
"I have seen no evidence for..." Design, intent, believabilty, efficacy...etc.
Is it manifold/induction injection, duct/swamp cooler, venturi assisted refrigeration, or????

As for "Scoffers United", we are united only by the effort to keep thee honest and useful in providing us data we are not able (or too lazy) to gather ourselves, and do wish to keep you sufficiently rewarded to keep doing it. And we would make offerings of beer were we able to get it there, but it cost too much to ship, so we drink it ourselfs, in your name & honour.

You may be interested in going to MGExp>Motorsports and reading the ongoing several aero related discussions, most notably my "Aero Surprises" story.

FR Millmore

Dominic..just trial fitted a length of 4 in to see if it would go in..and it does. Will cut and trim so air goes close to K&N and try soon to see how much more temp reduction possible. see pic

Neil Ferguson

Steve..thanks for bumf on water trial (?) was with a desert blower ( as used in Oman and tents in the Rub'al-Khali ) fitted onto front bumper visibility was poor ..see principal below...will now use in bedroom....

Neil Ferguson

I have no dynamometer to support these impressions, but I don't feel as if I've more power from the engine in cold weather (of which we have lots in northern New England) than in the heat. While I appreciate that increased gas density in the cold might load more oxygen into my carbs, all else equal shouldn't I feel some boost? What am I missing, O' engineers?


Ken Korey

If the csrbs are right at 70F, they will be significantly lean at below freezing, never mind at zero. That will lose you more power than the temp gives. In fact, if it is cold enough (-30F), a well tuned SU car may require near full choke to run at all - but it will fly!
When I was doing service tunes on daily drivers in Pittsburgh year round, I always set carbs for expected average conditions, and recommended customers bring the car for free adjustment spring and fall. I started setting them outside after a tune, but soon learned the
"offset" for temps, most useful if we had the occasional warm winter day.
Noticed my Mazdas, which are self adjusting, run like the wind in zero F, but drink accordingly. Watch for blue lights and nasty papers on the Mass Pike in winter!

FR Millmore

Thanks, Fletcher! I knew there must be a good explanation, because my conjecture seemed pretty loopy even to me. But I do get better lift on a cold morning if I'm not icing up.

Ken Korey

This thread was discussed between 10/07/2012 and 14/07/2012

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