View Full Version : TR4/4A New TR4 Restoration Project

02-04-2012, 08:52 AM
Hi All:

I am in the middle of total body off restoration on my totally standard 63 TR4. I will be keeping it as standard as possible for purity but am really interested in to making a couple of changes:

1) Exhaust System - I really like the dual out exhaust look of the TR4A's. The std TR4 has a single outlet. Is it possible to add a dual system to a TR4 ? I checked the exhaust manifolds outlets and they seem to be the samne for both cars

2) TR6 Engine - I am think of this but has anyone out a TR6 engine in a standard TR4 as I'm sure you know that the sound of a 6 engine is wonderful. Does anyone know if there is a reference site on how to do this ?

Many thanks for any advice you can give ?


Geo Hahn
02-04-2012, 09:13 AM
...I will be keeping it as standard as possible for purity but...

1) Is it possible to add a dual system to a TR4 ?

2) has anyone out a TR6 engine in a standard TR4?

Wow, that's some 'but'. And I thought I was comprimising originality when I went with a spin-on filter and H4 headlamps. :smile:

Anything's possible with time and money but I think the challenge for the exhaust system will be that hole in the cruciform that the current single pipe passes thru.

Considering the engine swaps some have done the TR6 engine should be a manageable change but I believe that the 6, whilst being a bigger engine, is not necessarily more powerful than the 4 you have now.

FWIW, both changes (IMO) would greatly reduce the value of the car -- not that that should necessarily be your priority but something you might think about.

02-04-2012, 09:32 AM
Exhaust.yes it can be done, a friend has the 2 pipe system on an early TR4. Eliminate the center muffler and I think it fits right in. However he may be using a TR4A manifold too.

02-04-2012, 10:37 AM
There will be interference issues with the steering rack trying to drop a TR6 engine onto a TR4 chassis.

Besides, a well sorted TR4 will run rings around a TR6. (Puts flame suit on.)

02-04-2012, 10:37 PM
I had a '63 TR4. I've tried in vain to find it so I could make amends for all the bad things I did to it.

OK, I'll let that pass. It's probably in a wrecking yard stripped to the frame by now.

Having made some mistakes, I'd strongly recommend you not change out that engine. A TR4 engine is one heck of a great engine, and as Geo says, devaluation will be the first real ramification of any such change. There will be plenty others, and I'm concerned they wouldn't be positive.

As for the exhaust, I can see why you might want to do that, but you'd have to change out the exhaust manifold and there may be other issues with the pipes underneath. I'm not certain, but I doubt there would be an issue with the cylinder head--you should check.

Good luck, but I'd stick to your initial inclination--stock, except for maybe a few items of popular preference (steering wheel, eight blade fan, auxiliary electric fan, maybe, maybe).

Andrew Mace
02-04-2012, 11:21 PM
If the "look" is really what you're after....


$70 or so.... :devilgrin:

02-04-2012, 11:53 PM
For what it's worth I would tend to agree with the majority here and say go for the exhaust swap but keep the TR4 engine. I had a '67 TR4A IRS and IMHO it was as fast as or faster than my TR6 and would run 80 mph all day on the highway, which my '76 TR6 with stock 4-speed will not do comfortably (or economically). This is why I'm looking for an OD unit for my 6. It's your car so do whatever pleases you but the TR4 does have good power. The TR4A with resonator and two oval mufflers had a sweet sound all its own. I respect the purists' opinions on originality but support the right of the individual to express his own individuality in building his LBC. If it devalues the car so what as long as you like it; you're paying the bills. Good luck with your resto and keep us updated with pics.

02-05-2012, 06:01 AM
For what its worth, I don't have a 4, but do have a 3B that has the 4 engine and a great exhaust look and sound.

I have a set of jet-coated headers that run into a long oval Cherry Bomb muffler and exit through twin chrome-tips from Flowtech. I put 1/4" red tape between the chrome and black and it really looks great. Kinda' like an Ansa exhaust. The red tape goes where the yellow tape is on the picture.

I used to have a Monza muffler and twin chrome tip outlet but didn't like the sound as it was too quiet for my taste.


02-05-2012, 07:20 AM
I wonder how different the gear ratios are between the TR4 and the TR6
maybe some one can fill in the TR4

1st 2nd 3rd 4th OD
3.14 2.10 1.33 1.0 0.82

and what the engine size,
I know the TR6 is 2.5L original 101 hp for 71 assuming at the flywheel
torque I am guessing somewhere around 143 foot pounds, the manual gives it in 1719 lbf inch what ever the heck that is

of course mine is 200 hp and 187 foot pounds at 5500 rpm


Tim Tucker
02-05-2012, 07:55 AM
The gearbox ratios are the same. The TR4 has a 3.7 rear end. The TR4 has a 2138cc engine (with 86mm liners). The HP rating was 100@4600rpm and the torque was 127ftlbs@3350rpm.

I hope to tear into my TR4 engine this spring. I am likely to go with larger 89mm liners (https://www.bpnorthwest.com/.sc/ms/bdd/ee/10095/Piston%20and%20Liner%20Kit%2089mm) for a little instant power.

I would not consider a TR6 engine in my TR4. If I had to change out, I would have a friend of mine build me a mild version of his 4-cylinder Ford motors. Smaller, lighter, cheaper, with more power. IMO.


02-05-2012, 09:30 AM
The rear axle (for the US) was the same, but the TR6 had larger tires (stock), for a slightly higher overall ratio. But the heavier body, heavier engine, and emissions junk (in the US) conspired to make it slower overall.

Personally, I'd think the Moss blower kit (or a DIY) would be far preferable to trying to swap in a TR6 motor. Or if you really want to keep it all Triumph content, a TR8 motor should fit fairly well and give a real boost in performance.


02-05-2012, 10:58 AM
Well I can confirm a 4A manifold will fit, no problems at all, I put one on a couple of years ago, it ties in nicely to the TR3/4 exhaust pieces right at the rear gearbox mount. Based on Jerry's comments, you could probably run a full 4A set up in there with the dual rear pipes with no problems, but I haven't done it.

Other than bling I'm not sure it does much, I'm going back to a stock setup just because I have a cleaned up manifold now and a stainless downpipe.

02-05-2012, 11:35 AM
Personally, I'd think the Moss blower kit (or a DIY) would be far preferable to trying to swap in a TR6 motor. Or if you really want to keep it all Triumph content, a TR8 motor should fit fairly well and give a real boost in performance.

As the owner of a supercharged TR4A and a TR8, I have to agree with Randall's suggestions. The Moss kit really is bolt-on, and includes everything you will need. I wouldn't put it on a tired engine, though. And if you are going to do all the work for an engine swap, the Rover aluminum V8 is very light, compact, and can easily be built to supply 200 HP (and significantly more than that, though I'd be wary of any more power in the TR4 frame and drivetrain).


Tim Tucker
02-05-2012, 05:39 PM
Good Lookin' TR3-V8...Whose is that?