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MG TD TF 1500 - Tubular exhaust manifold

Any views as to the benefits or otherwise please? Agreed probably not worthwhile on a std engine (other things to do first). I am thinking more of the next step after having raised the compression, fitted a sports camshaft, some porting, timing advance, etc. Don't want to go down the supercharger route, owing to much higher cost, ditto roller cam followers.
Dave H
Dave Hill

Dave I have no direct experience with those on a MG T but do have experience with other British cars used in vintage racing -- Mini and Turner. Based on that experience I agree with your comments that they may not be worth the cost for a normal T. I do not have the web site readily available but the person in the USA who makes and sells those is a gentleman named Manley Ford AKA Manley racing. All I can say is that they do provide some increase. Nothing to blow your socks off but perhaps in the 3 to 4 HP range.

As you are probably keenly aware there is not magic bullet to increasing performance in these cars. Seems like you do one thing to add a couple of horse power and then another to get some more, etc. However, you do need to look at modes using a systems approach rather then just a piece here and a piece there. You also need to consider the issue of reliability. My racing friends drive me nuts when the last thing is reliability and first is increasing performance.

I recently went thru the same decision process of upgrading my TD and here is what I determined. The cost to build a engine to compete with the gain you get from a supercharger was more then the cost of the supercharger. I approached it from the point of view to make it as reliable a engine as I could. This is getting long so I will not belabor this with the details. If you want them let me know.

IF you do NOT do the work yourself here are the costs just to improve the head. Enlarged new valves, new guides, hardened seats are the materials and add the machine work to put these in was in the $600 to $800 range. Porting was was another $500 to 600. When that is done you get around 5 HP. You will have in the range of about $1400 just for labor for 5 HP. Please do not forget new push rods and tappets when you do the head. Oh and also you will want to consider rebuilding the rocker assembly. I had mine rebuilt for $225 by Rocker Arms Unlimited, USA. Roughly you are $2300 or $460 per HP.

If you just add a super charger you go from 52 HP to about 73 HP at a cost of about $4300 USA. That is about the cost of $200 per HP.

Do not forget to consider switching to a new 4.3 rear end to really see the performance from all the mods and new upgraded axles while you are in there. Cost in the neighborhood of about $1400 USA.

Hope this helps you with your analysis.

Joe





JWP Policastro

I agree with what Joe writes - also note that not all tubular headers are the same. Not all will accommodate carbs under the bonnet.

Just installing a roller cam or a supercharger will yield a significant HP increase, all other things being equal. See mgtrepair.net for supercharger information and references, etc.

Tom Lange
MGT Repair
t lange

Dave. I have one of Steve Bakers headers from the U.K. It is very well made and I am quite happy with it. He makes them as just an exhaust header or with a integrated intake which is what I am running. I do recommend having it ceramic Coates as it will further drop the under bonnet temps. At the time Steve didn't offer this service and I didn't have it done locally. But may in the future. I also had him ad an O2 sensor bung in the collector. Pipe aligns with stock exhaust systems and is designed to fit both LHD and RHD. There is a bit of a performance gain I'm sure but this was my first XPAG build and I have made many mods to it including full roller cam and rockers, billet crank and rods, forged pop up high compression pistons, H-4 carbs etc. not having owned or operated a stock XPAG I can't give comparisons related specifically to a header ona near stock XPAG but I would presume that the free flowing characteristics of a Tri-Y header and its overall design would help with Miss range Torque and add a few HP over stock cast exhaust manifolds But I don't have any numbers to back that up. Contact Steve and talk to him I know he has dyno'd a few cars and may be able to answer your questions better

Bill Chasser
TD-4834
W. A. Chasser

Steve Baker designed and built header when I got it

W. A. Chasser

Thanks guys. Its a TF XPAG. I have done all the basics myself. Rebuilt the engine, magnafluxed crank, all balanced, lighter flywheel, bored to 1330 cc, 9.2:1 comp, porting to match manifolds, MGB distributor reworked by Jeff Schlemmer, Edney sports cam, shortened push rods, modified cam followers, sports exhaust. I am running a Ford 5 speed gear box and a 4.55:1 axle. It goes well, but just wondered if a tubular manifold is a worthwhile investment.
Dave H
Dave Hill

MG XPAG normally aspirated, Abingdon Performance Ltd. street performance camshaft, XPAG 1350 CC dyno results: 75 HP, 72 lbs/ft of torque. more than 64 lb/ft from 2600-5200! HP. (About 10 F/# more torque @ 5,200 RPM than stock) An HP increase of about 40%!
Torque increase about 15%
A very flat torque curve!!!
This type of HP & TORQUE curve can not be produced by a flat lifter cam.
This engine has MK 11 valves, etc, an extractor exhaust manifold, stock OEM cylinder head, ported by XPAG engineering 9.8:1 CR.
Soon expecting to get results from a dyno report with my Abingdon Performance S/C cam and one of Tom Lange's Superchargers.
See my re opened XPEG dyno report post for graphs of this XPAG engine.
Len Fanelli

With all that done you only have one piece left and that is the headers. When you list the actual mods, it seems to be a no brainier. What are you waiting for?

Joe
JWP Policastro

Just looking for corroboration, I guess, that I might get a few bhp and I wouldn't be wasting a bundle of money.
If I were starting again I might go for the roller cam, etc., but from where I am its a non- starter.
Dave H
Dave Hill

Dave, I put a couple of KR circular filters into the filter casings on my TF1250. I didn't use the perforated covers. I had just had it dynoed: after the filter change, on the same dyno, I got four more HP at the wheels.

And the visual difference is minimal, compared to a tubular exhaust.

David
DavePro

Thanks, but I thought there were no alternative filters that would fit in the Vokes filter housings. Or were these cut down from larger filters.
I've looked into that and its definitely an option. I also wondered about making short, i.e., very short, but radiused stubs, to aid airflow.
Dave H
Dave Hill

This thread was discussed on 29/11/2016

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