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Kretean

TR3A Performance Engine Rebuild Advice

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Looking to get some input / advise on a 1961 Triumph TR3A that I am looking to rebuild the engine to make a fast street car. I'd like input on larger Pistons (cast or forged), Connecting Rods (stock or forged), Crankshaft (stock, nitride, billet steel), how to strengthen the bottom-end 3 main bearings to make it strong, and reliable (bullet proof, if possible).

 

What modifications would be recommended for the cylinder head? Target HP would be about 160hp (more if possible)

 

I haven't decided if Naturally Aspirated or Supercharged is the way to achieve these goals, but would like to keep redline at 5000 rpm. This will be a fast street car, and not a track car. I've heard that the Judson supercharged TR3s were putting out close to 200hp. Not sure how true that is, but I see that Moss has a nice supercharger set up for the TR3 (a bit pricey, but looks like it would be an option provided the bottom end can be built strong enough to handle the supercharger, and limit boost to 5-6psi).

 

Drivetrain would be converted over to a 5spd manual, and a Limited Slip Differential, either a Quaife or Gripper to handle the added power (need to do more research on this). All input is welcome!

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Well as you can see from the 132 views but nobody contacting you, your listing of almost everything and such a exquisitely open number of questions is filling people with dread.

If you want to go through it with me contact me by PM, click my avatar and send me a message and after a discussion we'll see what can be arrived at.

 

Mick Richards

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Well as you can see from the 132 views but nobody contacting you, your listing of almost everything and such a exquisitely open number of questions is filling people with dread.

If you want to go through it with me contact me by PM, click my avatar and send me a message and after a discussion we'll see what can be arrived at.

 

Mick Richards

We were all waiting for you Mickey ;)

Stuart.

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I would love to have a go at building more of a performance engine.

 

I have no machining knowledge.

 

But always wonder if its possible from the parts available off the shelf.

Eg a moss 89mm liner/piston set

A cam and followers ( thats a minefield in itself)

Light Flywheel. Electronic ignition.

Steel cranks are too expensive so sending original out for some sort of toughening treatment.

Sending the head off for work or buying a stage xx head.

All for couple grand of course.

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Hi Kretean,

 

You can go different ways to power up your engine.

I dit a lot off experiments to power up my TR2.

The best option a tried is the Judson Supercharger.

 

The TR engine with a Judson produce about 40 % more HP with 4-5 Psi pressure, but this is only archived when the Judson is at low temperature.

How longer you drive, the Judson heats up. This is because the Judson is placed above the exhaust and the contact from the vanes to the body.

Also is the Holley carb to small for the higher RPM range.

 

Beside this, the drivability off the Judson is fantastic. Very stable idle speed, a lot of engine torque at low RPM.

Starting the engine takes a little while, because the petrol mixture from the carb to the inlet manifold is a little bit longer.

 

I now almost finished building my TR2 with a Shorrock Supercharger with a 2" SU carb. This is the best way to go because.....

The Shorrock is placed on the other side of the engine, so it can't heat up by the exhaust. And its vanes make no contact with the body off the Supercharger.

In addition this Shorrock Supercharger can gives much more PSI than the Judson.

 

There are some pictures from the Judson and Shorrock on my website. https://www.triumph-tr2.com.

 

Robin

Edited by Kutscher

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Hi

I just bought a Judson S/C to fit my TR4a.  It will need a rebuild. Anyone have any experiance? Als I am looking for a good quality scan of the original installation instruction. 

 

regards

 

Boudewijn

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I fitted a Judson to my TR4  some years ago with very mixed results.  As a bolt on 'goodie'  it looks fine but to be honest you can get more power out of a TR engine by rebuilding it with up-rated components.  When I converted the TR4 to Webers i got reliable power  in the 150 bhp range. I'm now getting 175 bhp at the wheels with my TR3S  

i may still have some paperwork for the Judson installation. If I can find it I will pm you. 

hoges. 

blower 3.jpg

DSCN0011.jpg

DSC03272.JPG

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TR3S = Twin Cam engine made by the factory mainly for Le Mans cars in the TR3 and TR4 models back in the day. Those cars with one fitted had the S adopted at the end to signify Twin Cam fitted.

Never developed and using the SU DU6 Twin Choke carbs. Nearly unavailable now with a few ( less than 3 I think, out of maybe less than a dozen ? engines made)  engines found, and in recognised car restorers hands. 

Always possible there may be a ghost engine lurking but unless you fancy finding it and then reselling to one of the above specified restorers ( reworking and funding the specialist engine parts maybe required to get running will likely cost far more than the engine purchase) for much more big bucks than you paid for it, probably not worth the hassle of trying to find it.

Mick Richards

Edited by Motorsport Mickey

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9 hours ago, Richardtr3a said:

Hi,

What is a TR S. I am not sure I know. Please help.

Thanks

550166211_LeMansTR3S3.jpg.f9ffa1b52a550e84afc9cdb58c62bf5f.jpg693757242_LemansTR3S1.jpg.6d73eb948d6c9c1fe507ed1ab84ce7bf.jpg1144875058_LeMansTR3S4.jpg.86413a1bafd8c9cd658548516e63af9f.jpg

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Richard 

you can see the car in question here. 

A tr3 engine- not the hens teeth rare Sabrina twin cam engine that Mick talks about. It does have the funky twin SU’s tho

1959 TRIUMPH TR3S EVOCATION https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F332815718696

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4 hours ago, Motorsport Mickey said:

TR3S = Twin Cam engine made by the factory mainly for Le Mans cars in the TR3 and TR4 models back in the day. Those cars with one fitted had the S adopted at the end to signify Twin Cam fitted.

Never developed and using the SU DU6 Twin Choke carbs. Nearly unavailable now with a few ( less than 3 I think, out of maybe less than a dozen ? engines made)  engines found, and in recognised car restorers hands. 

Always possible there may be a ghost engine lurking but unless you fancy finding it and then reselling to one of the above specified restorers ( reworking and funding the specialist engine parts maybe required to get running will likely cost far more than the engine purchase) for much more big bucks than you paid for it, probably not worth the hassle of trying to find it.

Mick Richards

There is about 6 engines around now.

Stuart.

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So this is a replica, not the original car, but with the same registration number.. Do I remember reading about another tribute car being built ?

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Glen made Paul's car, pictured above.

Bob.

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Hi,

Clearly you are facing a number of options,from my personal experience the Moss supercharger kit is a very complete package. I bolted one onto my TR3 with an engine of unknown vintage but it had a great oil pressure, I am now about ten years from running this and I use the car for work (around London) and any use as it is such a pleasure to drive. I have other supercharged cars and the driveability of a low pressure supercharged car is one to behold. Power reading on the rolling road is 118 bhp with no other modifications to the engine other than a four branch exhaust and system. I suppose that at the engine/flywheel that equates to around 150 bhp but as ever the reality is what is at the rear wheels. The Eaton supercharger that Moss use is one of the finest bits of engineering you will ever see, and the technological advance over older types of superchargers is light years.  

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8 hours ago, stuart said:

There is about 6 engines around now.

Stuart.

And each one is slightly different!

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20 years ago i restored my TR3 with Revington full suspensions kits and anti roll bars. The handling is excellent. Very safe and pleasant to drive and very reliable. But now, after years driving a 200HP diesel daily car giving incredible low end torque, i find my TR much too lazy so i want to get more than just the stage 2 head i currently have. 

For my new engine, road use, i am considering 3 options:
 - 87,5 regular Piston/liners with a rally cam and 2 or 4 fuel injectors
- 89mm Revington Tr re-enforced liners and forged pistons with a milder hot cam and 2 or 4 fuel injectors
 - 87,5 regular Piston/liners and a Moss supercharger. With and additional injection price will be to much for me. Maybe latter especially if i what to go to flex fuel.

In all cases, a programmable timing distributor

My target is also not to go over 5500Rpm, keep the engine and car reliable, and an acceptable town drivability
i will keep the lambda probe i already have to fine tune fuel ratio (as i im fully satisfied with the service it gives to tune my current carburettors)  in case of supercharger option and likely use a basic audio knock detection to avoid problems.

- What experiences return do we have for theses solutions ?
- About 87,5 and 89mm liner/piston kits and special head gaskets, have you noticed better products than others ?
- How is low end with a 270, 208, 290° Cam ? With large bore, where is the reasonable limit to drive pleasantly in traffic ? Is E85 helping the get a better low end behaviour ?
- Can the overdrive gearbox and rigid axle equipped with a Quaife ABT cope with the torque of the compressor ? Does the axle need a modification to avoid torsion and stress on propeller shaft under heavy acceleration ?
- About head work, for my TR and mini engines i never used re-enforced unleaded valve seats. Do you think that it will be compulsory with such hot configurations ?

- For a LHD car, does the compressor installation needs body modifications ?

Thanks by advance for your help !


 

Edited by Kistinie

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Welcome,

a name would help in making things friendly.

Sure you will get loads of opinions on your questions.

 

John.

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Francois - I am by no means an expert on high performance 4 pot engines, but have some observations which may be helpful.

I hadn't read the earlier posts from last year when I first read your most recent one today. It would seem you have have downgraded your engine expectations in the intervening period which makes for some interesting options. You have obviously got used to driving high performance modern diesels, but I wouldn't be surprised if your modern car weighed the best part of two tons, a hell of a lot more than a 3A, so to get equivalent torque performance, in my humble opinion, you won't need anything like 200bhp and not even 160bhp.

The 4 cylinder engines are well known for their torque in the first place and even mild tuning can make a big difference to their driveability - it is also very easy to destroy the torque characteristics of these engines, and that normally happens by use of an inappropriate camshaft.

When I approached a very experienced TR engine builder about a typical spec for my TR4 engine, I explained I didn't want a racy engine but rather a really torquey one. He was pleased as he said he had made more money than anything else rebuilding rebuilt 4 pot TR engines where fast road cams had been fitted because these just didn't suit these engines. I didn't have a vast budget so the spec we settled on was an 89mm piston and liner set,  a high torque cam  ( ie something like a Newman PH1), an unleaded head but otherwise standard ( I asked about improving the head and he said he could quite happily take another £700 off me to gas flow and improve the head but it wasn't absolutely necessary), a Phoenix sports exhaust manifold and system , retention of my fully restored HS6 carbs with slightly richer needles, electronic ignition, all fully balanced and a lightened flywheel.  If you are not proposing to use more than 5500 rpm, provided you get everything fully balanced, I don't believe you need to go overboard with steel bits inside your engine, but if money is no object, then no harm in doing so.

Well everything he said turned out to be true - I have a lovely, smooth and driveable engine with loads of torque which didn't cost a fortune -  I tend to use high octane petrol as far as possible which I'm sure helps. Undoubtedly this could be further improved but the fact that you say you already have a stage 2 head and yet want more torque makes me wonder if you have an inappropriate cam.

I can't help feeling with the basics of what you already have, you should be able to achieve a really torquey unit for not that much money - for torque, you need cc's so go for the bigger piston and liner set. However, there is no doubt that going down the supercharger route will give you tons of torque and power, and sound great as well but at a fair old price!

Moving onto the drivetrain, I have no actual experience of how you improve your back axle, but I'm sure others will be along to recommend appropriate improvements. I don't think you need to worry too much about your propshaft other than replacing the UJs with heavy duty ones, but you will need to do something to your gearbox/OD if you want reliability - my preference would be to go for a Stag box with an uprated OD  as these are the strongest gearboxes you can have in a roadgoing car.

So definitely an exciting project with lots of angles but I'm sure we will all be interested is seeing and hearing how it develops.

More than happy to discuss further if you want to contact me so have sent you a PM ( personal message)

Cheers  Rich

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Rich

have you every had your set up on a rolling road what torque and power did you get - where in the rev range ?

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Hamish - its never been on a rolling road but it pulls from literally 1000rpm and then goes all the way up to 4500+ but I normally change gear then although it will easily pull round to my redline at 5500 in 1st and 2nd in no time at all. I have no idea of the power output but I would guess about 120bhp

Cheers Rich

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