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MG TD TF 1500 - How many extra horsepowers from a head job?

My TF1500 has the original XPEG. Apart from pertronix ignition and K&N filters the engine is stock, seemingly in vgc with minimal oil consumption and compression 155-160 psi on all four cylinders.

I am considering as a part of next winters excercises to remove the cyl head, have it skimmed to 9:1 c.r., lead free porting and the fitting of an extractor manifold. As nobody really are experts on these engines her in Norway I might send the head over to Peter Edney in the UK.

But;

What would the educated guess be as to increase in HP and "get-up-and-go" with this kind of tuning without removing the engine for balancing, flywheel lightening and a hotter cam?

Is it worthwhile, or should I just go the Supercharger way. (That is a bit fiddley in a TF.)

Thank you for your responses,

Jan
Jan Emil Kristoffersen

Hi Jan,

My TF 1250 has a Mangoletsi tuned engine. They were the doyen of cylinder head and manifold tuning in the 1960s. Due to the death of the owner whilst the car was being restored it has been laid up for over 40 years and the tuned engine has never run. However I had stripped everything down for examination and the head, ports and manifold were beautifully polished. I don't know what difference this has made to the power output but the attached photo of a letter from Mangoletsi states a 25% improvement. Just look at the cost though - £35 for the big valve, ported and polished head and special inlet manifold!


Cheers


Jan T


J Targosz

My TF 1500 has been Stage 3 tuned as per the Special Tuning Manual

It was measured at 75 HP at 5000 RPM (projected 84 HP at 6000 RPM)
They didn't want to run it over 5000 RPM.

The compression is 9.5 to 1. In retrospect I wouldn't shave the head this much as it precludes future rebuilds)

But it is the same HP as my TF 1250 with supercharger on same dyno.

Both have the stock exhaust manifolds

I have nearly as much HP as the early MGB 1800 cc engine but much less weight and with my 4.1 rear end I can outrun most MGB's, especially in the North Georgia Mountains, including the"Tail of the Dragon"
Don Harmer

Before you skim the head, keep in mind that XPAG and XPEG cylinder heads are not as plentiful as they used to be. It might be wiser to fit high compression pistons. But it wouldn't be cheaper or easier.
Steve S

"lead free porting?" I assume you are referring to valve seat inserts. They would't really do anything for hopping up performance. Inserts aren't a bad idea, but that can be put off until the compression gauge says it is necessary.
Upping the compresssion ratio from 8.3:1 to 9:1 will add a little spunk over the entire range, but not much.
Adding tubular headers will add a few horsepower but the stock exhaust manifolds are actually pretty well designed.
You know, 8.3:1 is not a bad ratio for supercharging. Contemplate how much time & money you will spend on the headers, inserts and milling, then compare that with a supercharger package with less time invested. There's no comparison in performance. Then imagine how much your car will appreciate in value with a blower.
I'm really prejudiced when it comes to superchargers.
JRN JIM

Thank you for your opinions.

I omitted a word, should be "lead free conversion, porting ...."

I sum up your opinions to maybe 5-10 hp gained on a head/header job before cam change. So a supercharger is obviously the budget way to more power. And if the crank breaks there are new ones out there to be bought.

And I believe someone are making new XPEG blocks now if I throw a rod?

regards,

Jan
Jan Emil Kristoffersen

Jan - please see my page at mgtrepair.net, if you are interested in a supercharger, a number of which have been fitted to TFs. Dollar for dollar, it is the least expensive way to get a guaranteed 45% increase in HP! You would spend a similar amount on porting and polishing a cylinder head, for perhaps a 10% increase.

I'll be happy to help in any way.

Tom Lange
MGT Repair
t lange

Tom,

I have read your homepage over and over again, as well the report from the englishman in TotallyTtype, and everything about SC on this BBS as well. I cant really make up my mind whether a SC is too radical a measure or not. And there is of course the hassle of moving the starter switch, rerouting the tubes for the heater etc. But it surely is tempting. And a grand conversation piece as well, once it is under my bonnet.

PS: The roadster gaskets i purchased from you are great!

regards,

Jan
Jan Emil Kristoffersen

Jan, another point of reference is what I have done to my XPAG TD. I had the head skimmed to provide an 8.2 compression ratio, installed a 4.3 rear axle ratio and topped it off with a Marshall-Nordec supercharger. The Pertronix ignition in my distributor was another plus. I decided on the moderate compression ratio to take advantage of modern day fuels and to minimize any damage to the crankshaft which has been magnafluxed and balanced. The blower provides about 3 to 4 lbs. maximum pressure due to the pulley ratio I used, again keeping in mind the load on the crankshaft. I no longer have to pray when the radiator of an eighteen wheeler truck fills my rear view mirror. Now, I can easily accelerate away to a safer distance without the RPM going sky high.
Jim Merz

One other aspect- when you install a blower, it includes a new carb and, in your case, you'd remove a pair of very desirable SUs worth over $1000 on the open market AND an intake manifold & air cleaners you might sell for around $500 or more (what's that monetary equivalent in Norway?).
JRN JIM

Yes , that is a point, although there is hardly a domestic market for T series parts in Norway there is always the Ebay option. 1.000 US dollars is approx. 6.500 Norwegian kroner. One litre of gasoline is 15 kroner, and a 500 cc can of lager beer is 25 kroner (almost 4 USD) in the supermarket. ( High alcohol taxes are supposed to reduce alcohol problems in society.)

Last night I reset my valve clearances after 11.000 miles of driving. One valve was at .015' while the others were spot on .012', so valve seat recession does not seem to be an issue. ( I add a spoonful of two stroke oil when I fill up the petrol tank. )

regards,

Jan
Jan Emil Kristoffersen

Jan,the man to consult about superchargers and T Types in the UK is Steve Baker. He's done lots.

http://www.stevebakermg.co.uk/

Gave a very interesting talk on the subject at the T Register Rebuild seminar in March 2013.

David
David Wardell

Steve is the UK agent for the blower I sell. I believe the dollar price is more advantageous right now.

Tom Lange
MGT Repair
t lange

Yes, it seems to be a difference of 1200 dollars in your favor Tom.

Bought myself an MGA 4.3:1 diff today..

Regards,

Jan
Jan Emil Kristoffersen

This thread was discussed between 25/07/2014 and 27/07/2014

MG TD TF 1500 index

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