MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - I guess I expect more for the money

http://www.ebay.com/itm/140910390586

Stock crank and rods...and 150 hp???? Only trick thing I see is the header. And really...150 hp.....I want to see the proof. Any thoughts?
L E D LaVerne

Uhhh, yeah...sent him an email. Interested in his response, if any.
Gene Gillam

Two things I noticed is, why still retain the original oil filter and unless I'm missing something, there's no mention of an upgraded crank! 150hp on an original crank, at what RPM? Doesn't sound very good to me. 10Gs? Well, it's pretty anyway. PJ
Paul sr

I agree LaVerne.
As I look at his list of what was done, my engine has had all of that except larger carbs and manifold. I dont think that would double the HP.

Jim B.
JA Benjamin

I don't much like seeing washers under the head bolts; they don't even look hardened.

You need to do a whole lot to an XPAG to get 150HP out of it - and that makes it a flat-out racing motor, not a street job. I'd AT LEAST need to see a whole lot of magnafluxing, re-shaped combustion chambers, forged pistons, forged crank, a pretty aggressive cam, better valve seals, completely balanced, shaped intakes, modern rod bolts and head studs, etc. A rattle-can paint job doth not a good engine rebuild make...

Tom lange
MGT Repair
t lange

FWIW, this is what I do to rebuild a stock engine. A racing engine would be a whole other level of sophistication:

Clean and disassemble engine
To machine shop:
Hot tank all parts, bake and ultrasonic clean appropriate parts including oil pick-up, soda-blast block, head, pan, bell housing and timing cover, power wash everything with hot water
Magnaflux head, block, rods, crank
Measure and check everything
Bore block, as needed
Re-surface block and head a/n, check head thickness, bring head to Mark II specs
Complete valve job (new valves Mk II, bronze/iron guides and 120# springs )
Turn crank a/n, or polish
Re-size rods, polish, shot-peen if desired; replace gudgeon bolts with cap screws
Install new cam bearings
Balance ALL moving parts to ˝ gram
Scrape/rod out water passages, drill out drain hole if not already done
Clean out and brush out all oil gallery passages
Clean-out tap all bolt holes, smooth all mating surfaces
Measure rear main oil thrower and hand-fit
Clean out oil pickup
Thoroughly re-clean block
Rebuild oil pump
Install reground cam, new pushrods, re-surface/replace lifters
New 12.9 rod pinch cap screws and high-collar washers
New rod bolts
New head studs
New timing chain, tensioner spring, crank and cam gears, and keys
New main and rod bearings (Vandervell when possible)
Lighten and re-surface flywheel, new ring gear a/n, pilot bushing
Brass core plugs (naturally…)
Rebuilt distributor (Advance)
Rebuilt valve gear (Rockerman)
New water pump a/r
Check/replace thermostat (in modified original housing)
Re-assemble engine
Pump oil throughout with hand pump

Test run
t lange

This is the response I received:

"Hi, Thanks for your response. I am an MGA guy and a little out of sorts with mg td engines. I was informed by the previous owner, he raced MG TDs, MGAs, AH, Triumphs, etc., that the engine was rated at ~150 HP. I guess the only way to tell 100% is do an engine dyno. So what is the engine worth? I have communicated with other vintage MGTD racers and they have not questioned the engine build. I would appreciate to understand more."

And this is how I responded:

A stock XPAG (1250cc) or XPEG (1500cc) originally had 54bhp and 63bhp respectively (11HP and 13HP) so you can see why someone would challenge the 150HP claim...especially if, as you say, it hasn't been dyno'd.
Most "built" T-series racing engines have billet cranks ($2K),
Saenz or equiv rods ($900), J&E pistons or equiv (($800), lightweight flywheels ($450), racing cam ($400) and even then I doubt they'd hit close to 150 hp or be worth $10K.
For an engine like this one (without documentation that it's been balanced, etc.) you might be able to get $5K to $6K but not much more. There's nothing in the specs you've provided that indicates there's anything special about the engine...just looks like a typical
rebuild."
Gene Gillam

Power output? It's easy: 75 HP in the morning and 75 HP in the evening... check it out and year, you'll end up with 150... :)
R.S. Ralph Siebenhaar

Pretty much no way, without the above radical internals and maybe a blower. Could be a very short lived 150hp also. George
George Butz

My mechanic recently built a TR6 engine for a customer that was three times the brake HP from the standard TR engine on the dyno. I have seen the graph output from the test so i know it is real. The rebuild included triple Webers, custom exhaust, many trick parts inside and a strong 5 speed transmission. This is not a turbo car. So, if you can get 3X BHP on a TR6, is it not possible on a MG engine?

The TR customer also owns a new Ferrari, but prefers the TR for driving enjoyment. His next project is an early E Type. He invented some software gadget and is now having fun with his toys.

Question: What is the brake HP on a stock TD or TD? Is that the 58/63 HP we see in the books or is less?

Thanks, Jeff
JSL jeffrey

I was curious so looked it up. BHP is the HP delivered at the end of the crank with NOTHING (no water pump, no generator, no nothing) attached to the motor. HP at the wheels is after the losses for the accessories and friction and inefficiencies in the drive train. An engine dyno can measure BHP but a wheel or chasis dyno (you drive on rollers and chain the car down and put it in gear and run it) measures HP at the wheels. Friend of mine had one but no one wanted to pay to be dissapointed in their true output at the wheel (it was a good speedo check and he had a few takers with tickets pop for that) so he went broke.

Don't really know what "SAE Net" is but I think its related to HP at the wheels. Anybody know?

Thanks.

Jud
J K Chapin

I should have clarified that all of that about BHP etc. presupposes that I read it right and understood it right, neither of which are sure things.

Jud
J K Chapin

Jeff,
You may get 150 HP from an XPAG/XPEG but not with stock internals like the engine being advertised.

And according to Neil Cairns, the true HP from an XPAG is 11, the true HP from an XPEG is 13. The 54 and 63 you see is the bhp.
Gene Gillam

I don't dispute 150hp at all!
I base this on dyno readings I personally saw on a 1971 Honda 750 4 cyc engine that were off the chart!

Oh yeah ...did I mention that nobody noticed that somebody had removed the drain plug....and it was a very "short" run? ;-0 !

Yes it was "my" motor ...but not for long.
I think there are still parts of it in orbit.
David Sheward

Gene

The 11hp for the XPAG and 13hp for the XPEG refers to the RAC HP formula, which UK (and Australian) authorities used as a basis for vehicle registration charges. The following explains it.

http://www.designchambers.com/wolfhound/wolfhoundRACHP.htm

Ian

Ian Fry

It was also the (I think the major)reason Pommie engines had such long strokes - to keep registration costs down. It only used bore size for calculation.

Ian
Ian Fry

Some facts on engine testing that you may know:

Engine power is usually measured at the crankshaft (before the gearbox). Depending on the standard used for fixing the test conditions, one can get American SAE or German DIN power (among others less common). The more important difference between these standards is the auxiliary devices (generator, fan, etc) that the engine has to move when the power is measured. SAE standard allows to test the engine without some of these devices, so typically, SAE power is around 10% higher than DIN power in the same engine.

Rolling dynos can estimate the engine power at the crankshaft by measuring the power at the wheels, and then doing a deceleration test, where the frictional power loss along the drive train is measured, and added to the power at the wheels.

Jesus
J Benajes

Ian, interesting article. I wonder if this sentence fromn the article:

" The figure increasingly had little connection with an engine's actual output, so ratings such as 16/65 were seen, referring to an RAC rating of 16hp and an output of 65bhp.

with its reference to "16/65" explains the early MG nomenclatures of:

" M.G. 14/28, 14/40, 18/80 and 18/100 models, produced between 1925 and 1932"?

Jud
J K Chapin

Interesting short read. Particularly the RAC horse power.

http://en.wikipedia.org/wiki/Horsepower

Guess what I'm looking for is WHP so I can compare it to my rolling road dyno test.

L E D LaVerne

From the Wiki article cited by LaVerne: Brake horsepower (bhp) is the measure of an engine's horsepower before the loss in power caused by the gearbox, alternator, differential, water pump, and other auxiliary components such as power steering pump, muffled exhaust system, etc."


Based on that does anyone believe that a basically stock XP(?)G engine develops 150 hp or bhp or any other known type of horsepower? That is what the eBay seller is claiming.
Gene Gillam

Based on my graph of a fresh stock type rebuild and then the blower addition it looks like a 55 percent gain. If I throw that at the factory figure I'm producing 84 HP. 150 hp???? Maybe with nitro methane, 13 to 1 pistons, scatter cam and a 30 second life duration....but I doubt it.
L E D LaVerne

The question whether an XPAG engine can produce 150 HP is very interesting. And aside from testing the engine, there are some general and basic engine facts that can be called upon:

The two ways of substantially increasing engine power, keeping displacement constant are: increasing induced air flow mass (supercharging) or increasing engine speed (and at the same avoiding the loss in engine breathing capability at high rpm).

In applying the second method to an XPAG engine, there appear two important limitations: the first is the natural trend to choking in the inlet valve at high speed, that can be only avoided by increasing the valve section (larger valves or a 16-valve cylinder head). An important contribution would be reducing the piston stroke (and increasing the cylinder bore, to keep displacement constant).

The second limitation is the average piston speed, which is proportional to the engine speed and again to the length of the piston stroke.

In the case of the XPAG engine, the important limitations to achieve this power figure of 150 HP are the relatively small and only one inlet valve, and the long piston stroke (assuming that the internal parts would withstand mechanical and thermal stresses). A reasonable limit in average piston speed for a racing engine is around 20 metres/second, and an XPAG engine with a standard crank would achieve this limit at around 6600 rpm, which seems too low for attaining more than twice the original power, without supercharging.

It is well possible to obtain 150 HP from 1250 cc, but without supercharging, the basic strategies would be: a small stroke/bore ratio, four (or five) valves per cylinder, cross-flow cylinder head, hemispheric combustion chamber, tuned exhaust and inlet manifolds, and a powerful fueling device (typically multi-port injection or very large carburetors).

In short: the XPAG engine, with its basic architecture seems too limited for 150 HP, no matter what tuning work might be made.

(Hopefully, I was not too boring)

Jesús
J Benajes

L E D Laverne I guess I'm kinda dense but the curves on your graph don't seem to be labled completely enough for me to understand which is which.

The red curves show a very broad horsepower output over a wide range of RPM's. The blue curves are very proportional to RPM's I would guess that the blue curves are standard induction and the red curves are forced induction.

Neither set come up to the stated HP numbers for the Xpag. But if these are chassis tests then I guess that is correct.

The blue curves show a very sudden drop-off at 5500 RPM must be valve float. How come that doesn't show on the red curves? Different cam??
Cheers,
Bob
Bob Jeffers

Bob,

I think the blue are HP and the red are torque. The lower blue and lower red are a pair, and the upper blue and upper red are the other pair.

Charley
C R Huff

Charley is correct Bob. Lower lines are stock..Upper figures are with 6 lbs boost Eaton blower. 5500 rpm was my cut off point. Dyno tested at 4800 ft and from first hand experience I can say you get more at sea level...maybe 10 to 20 percent.
L E D LaVerne

This thread was discussed between 28/01/2013 and 29/01/2013

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.