Getting more juice

[scellis]

I have a original US spec TR6 with about 106bhp. What is the best/easiest way to get some more juice out of the engine, to say 140-150bhp?

[Bald Rick]

Hi

 

There ain't no easy way! Unless you take it into a specialist and say "make it go quickly". In which case be prepared to hand over your wallet!

 

The most straightforward way would probably be to buy a CP series engine complete and change it over. Or buy a CP cam, head, distributor and all the injection bits and pieces and swap them over. Whether that's the best way is a moot point.

 

Personally I prefer to mess about with carbs, different cams, modified heads etc. That can be a minefield for the unwary. It's also not cheap, a modified head alone can cost several hundred pounds. But for me, finding out what works and what doesn't is part of the fun of owning the car.

 

Of course the PI system is proven to work and provide between 140 and 150 bhp.

 

There are those far more experienced than I with TR6's and many who will have differing opinions, but I think they will all agree one one thing, if you're doing it yourself there ain't no easy way.

 

Tony

[Guest andythompson]

Depends if the engine is fresh or not...

 

Depends if you want the injection set up or not...

 

If the motor is reasonably fresh the easiest, cheapest power would be the following...

 

1.Fit HS6 Carbs... you may need a saloon manifold for the linkage and modded throttle cable

 

2.You need to lift the head and put in a decent camshaft + new followers... a Chris Witor custom cam is an excellent compromise.. bit less overlap than a TR5 but a bit more lift on the inlets... good for carbs

 

http://www.chriswitor.com/Chris_Witor_Price_List.pdf

 

3..You should get a late head 219016 or 219021 and skim it to 3.400" thickness ie 9.5:1 CR.

 

You will need to run premium unleaded

 

4.If you have the spare cash.. fit bigger inlets (37.75mm or 38mm) and fit unleaded seats and standard exhaust valves.

3 angle cut on seats.. no other gas flow work really necessary.

 

5. Get a 6-3-1 Alternate Pulse extractor exhaust

 

6. Distributor will need rebuilding to give less initial advance

 

Bolt it all together and find a decent Dyno that can tune SU's... this should get you 140-150bhp no problem.

 

If the engine is tired the same applies but you will need a rebuilt bottom end.

 

Do the same but fit injection or webers and you would make about 150-160bhp but spend a lot more money

[marvmul]

Agree with the recipe of Andythompson. If you intend to do it in stages, buy a stage 3 unleaded cylinderhead from a well known supplier now. You can't go around a modified cylinderhead when searching for more power, and perhaps balancing the engine. The other items are bolt on and you don't loose money when you put them later in. With a good modified cylinderhead, the engine will run more economically.

With the SU's real 150 bhp is possible, you have to realise that most real world US spec cars are 80 to 90 bhp and most PI's are perhaps 115 to 130 bhp. A perfect, not modified PI has 143bhp or 124 bhp if you are lucky.

[jellison]

I have a original US spec TR6 with about 106bhp. What is the best/easiest way to get some more juice out of the engine, to say 140-150bhp?

Best way is skim the head for about 10.5 CR (pointless over this on a lightly modded engine),

put a good a fast road cam in it - bin the twin SU's these are junk and will be killing it (as per the orginal spec vs the same age uk cars on injection). Get hiold of set of triple webber 40's (expensive though) or fina a FI - system - we might have one - ALL readey set for a fast road car - (won the roadsporst part of the TR Register champ in 2000 at first attempt - most of engine now surplus to requirement as full steel bonkers 260bhp!)

 

***If interested drop me a note or mail - also have the Full FI sytem - all pumps, etc, CAM, all rods and pistons, lightened flywheel and prbably a lot more!!!

 

We had a well balanced, cammed car with increased CR and worked 150 head on mddied injection - (this is not the easiset thing to get right), making around 180bhp - over this it get pretty expensive.

 

You can get 220bhp on the std injection (on a race engine) - for me iot would have to be FI or webber - the rest is largely a waste of time.

[marvmul]

- bin the twin SU's these are junk and will be killing it (as per the orginal spec vs the same age uk cars on injection).

 

All TR6's were delivered with PI or Stomberg carbs,no SU's were ever fitted. If you think SU's are junk, than either you are confused with the Strombergs, or you've no experience of a TR6 that is tuned, with the use of SU's.

[vanflyer]

Just to add my 2 cents, a skimmed head to 9.5 CR new rocker shaft and valves re seated, re-ground cam new bearings, overbore of 0.040 and a damn good tune put me back $7,000CAN. The Strombergs are not **** they are poorly understood and much maligned. The US cars were set up to run really lean, so change out the pistons and needle carrier to the later adjustable type, lower the main jet tot richen pu the mixture and fix all of the vacuum leaks and the car will be transformed.

[Guest andythompson]

I only suggested SU's as there are a huge selection of needles availible for a non-standard engine making correct tuning far easier... They are low tech compared to both PI and Webers and much cheaper (e-bay from a saloon + rebuild kits from Burlen) .

 

To say they will strangle the engine is total nonsense... on a road car they would be fine...

 

Early 3.4 Jags seem to do pretty well on just a pair of them.... it's all down to the correct needles.. as has been said most 70's carbs particularly the US Strombergs but also SU's were fitted with progressively leaner settings as the 70's progressed...

 

I am not trying to bias towards SU's.. I run sixes on both SU's and fully tuned Lucas injection...

Edited April 25, 2006 by andythompson

[Guest AndyTR250]

Heres a link to a thread currently running on the popular "British Car Forum" over here: http://www.britishcarforum.com/ubbthreads/...0&page=1#202772

You will find that we get pretty creative. I see a definite trend towards Goodparts triple carb set-up. Triple carbs run the gamut from Stromberg, SU, Mikunis, and Webers. Some are experimenting with electronic fuel injection. Moss USA is about to launch a supercharger: http://www.mossmotors.com/Shop/ViewProduct...teIndexID=47648

For a bone stock, low CR Federalized engine, this may be the least cost solution for maximum HP.

[jellison]

marvmul - trust me chummy I know what I am talking about. Fair enough OK stromberbgs not SU's - (just got off a Mini formum and talking about su's so still thinking su's!) - the basic twin system is hugely strangeling the engine if you want minor mods like a cam swap and a mild head skim. Why the heck do you think the US spec car had much less power than the euro spec ones.

 

I the swap to the original fi (who said anything about efi!?) is to much - then fair enough use what you have (strombergs wise and rejet - but to get any meaningful performance increase you will need to do a cam swap at the very least. (we are not talking alot for this!). The pi system can be tuned for what ever you have in the engine, and is fine to way over 200bhp (just has to be done by people that know the system).

[marvmul]

Why the heck do you think the US spec car had much less power than the euro spec ones.

 

The differences in power between US en European cars started with the six cylinder engines. Surely PI has to do with it, but it was also a matter of compression ratio and the proliferation of the anti pollution gear on the US engines. That no PI was delivered to the US, was also because of the clean air laws.

PI engines are intended not to rev over 5500 rpm, well, with 2 SU's filling of the cylinders can be made as complete as with PI. It is the flow of the cylinder head itself that limits it's maximum possible power.

If the cylinderhead has been modified for improved flow(stage 3), a PI system can extract more power than 2 SU's in the high rpm's, it's only then that the SU's and Stromberg limits will be apparent.

[Guest ron]

Marvmul

I'm with you on this one, there is nothing wrong with a pair of SUs on the TR6, in my view they are a better carb than Strombergs, if for no other reason than they are simpler to work on and tune. I think what Alex posted is relevant, the original poster wanted an improvemnt to his engine's performance not an out and out racer, things like PI conversions, stage 3 heads, Webers etc are OK if you've plenty of spare cash, but as I found out when I was a youth tuning Mini Coopers you can chuck a lot of cash at an engine and not always get a great return.

Scellis, I have an ex US engine, it has early big valve PI head, reconned SUs from Burlen, PI spec distributor, 125 cam [thinking of changing that?] and a Kenlow, it has plenty power for driving in modern traffic and returns good economy when touring, the suspension has been uprated as well, this probably gives better value for money than engine upgrades.

Ron

Edited April 25, 2006 by ron

[graham.dillaway]

I have a original US spec TR6 with about 106bhp. What is the best/easiest way to get some more juice out of the engine, to say 140-150bhp?

 

Thought I would add my personal experience to this discussion

I have an original US spec car This is what I did to uprate the engine/performance

 

1: Fitted SU carbs on BAE needles

2: fitted K&N filters

3: Skimmed the head 125 thou to take it up to 10.5 cr

4: Fitted tubular exhaust manifold 3:2

5: Fitted twin sports exhaust system

6: Fitted uprated camshaft BP370

7: Modified the distibutor curve to PI spec

 

After I had done this I had the car tuned on a rolling road and got 150 BHP

 

regards Graham

[Guest andythompson]

That compression sounds a bit radical for the average fuel around nowadays

 

I think the obvious thing from this thread is there are a 100's of different state's of tune available to us lucky Triumph six owners...

 

Personally I'm a Lucas injection person and have about 160-165 rwhp from a modestly worked injected six but I have also driven TR's and saloons using SU carbs and have seen the excellent results that can be achieved using the right combination of very modest parts...

 

I think the most amazing thing I have seen from an SU equipped car was a genuine 130mph "fly-by" on the M5 near Bristol at 2am on the Club Triumph Round Britain run... performed by a 1975 2500S saloon with SU's , K&N's, Big Valve head, Piper rally cam and 6-2-1 extractors... 155bhp at the wheels...

 

Do the research, keep asking questions... pay the money and make your choice....

 

Good Luck

[marvmul]

Maybe a stage 3 head is a little over the top for a road car, the difference over a stage 2 is essentially the reworking of the shape of the combustion chamber. A stage 2 is grosso modo limited to improve the ports.

I think stage 2 is necessary to get more power and economy. A stage 2 head, with fitting hardened valve seats, porting and skimming to raise the compression ratio isn't that cheaper than get the chambers reworked two to get the stage 3 head. If someone thinks of tuning further at a later time, he will not be limited by the cylinder head. But I agree that a stage 2 will do for a fast road car.

And getting a car that is fun to drive isn't about power alone of course. 180 bhp can be disappointing or boring if it is in a car with a crash suspension, duff brakes and bad steering

[jellison]

A PI engine not reving more than 5500 - what!?

 

Strange I have been driving one for best poart of 2 years at 6k + and there are fine to 6.5 for short bursts.

 

FI is fine upto low 200bhp.

 

The 2 little carbs on the poor 2 into 6 manifold is only ok up to a point - (and that is a low point) if you want real power.

 

If serious get FI or webbers. You might squeeze over 150 - 160 from the 2 carbs, but can't see more with the US cars having a lower Cr - you need to get this up - CR can be the deck height of the pistons or the amount off the head or both. Cam in US cars is lame as well.

[Joey]

Has anyone considered bike carbs, like a pair or Hsr48 mikuni's (suitable for up to 1700cc each) 

Straight 48mm bore on full throttle, no obstacles like the bridge in an su? 

I love su carbs but have been turned by bike carbs that are just a modern improvement on a su design. 

I'm intending on fitting a pair onto my engine when built. 

[Richard71]

I think there was an article in TR Action or maybe Triumph World magazine on someone's car with six Kawasaki carbs, yep, one per cylinder.

Maybe someone will be along with a link or perhaps even the owner of the car to give more info.

Richard.

[simonjrwinter]

How about dropping in a Rover V8?, lighter, more power, more torque, keep gearbox and drivetrain ( unless you go silly with the power), very little in the way of mods, easily reversible (for the purists).

My TR6 has been a V8 since 1982 and I’ve owned it for 11 years, I love it. It’s not a fire breathing monster, but rather a lovely smooth car, with enough power and torque for me (only a bit more than a good CP car but not a huge amount 170-180 brake?) no need for suspension upgrades, hugely reliable engine and very straightforward to maintain. My car does 30 mpg on a run at a constant 65-70. What’s not to like.

simon

[Andy Moltu]

If you are goping to do 65-70 whay's the point of tweeking th engine?

Don't get hung up on triple SU's or Strombergs - the firing order renders this an expensive blind alley.

Either inject - Lucas or electronic or triple Webers if you choose to change the carbs. Lucas sets come up from time to time. Beware second hand Webers/Dellortos - they may cost you as much in bits to get set up for your car than buying the correctly set up ones from new.

As Jon says the head will need work to up the CR and whilst you are at it get is properly worked. Even if no extra power it will pay back in terms of economy.

Replace the cam with one appropriate for your driving style and the chosen fueling option (Efi, Lucas PI, Webers or Twin SUs) The right cam requires matching with the set up.

When you need to take the bottom end apart, lighten the flywheel (pick up will be vastly improved), balance and tuftride the whole bottom end which is important for longevity.

The dizzy may need re mapping to avoid pinking low down (compression ratios of up to 10.25:1 can be set up not to pink on regular unleaded)

[astontr6]

On 4/25/2006 at 9:49 AM, marvmul said:

 

The differences in power between US en European cars started with the six cylinder engines. Surely PI has to do with it, but it was also a matter of compression ratio and the proliferation of the anti pollution gear on the US engines. That no PI was delivered to the US, was also because of the clean air laws.

PI engines are intended not to rev over 5500 rpm, well, with 2 SU's filling of the cylinders can be made as complete as with PI. It is the flow of the cylinder head itself that limits it's maximum possible power.

If the cylinderhead has been modified for improved flow(stage 3), a PI system can extract more power than 2 SU's in the high rpm's, it's only then that the SU's and Stromberg limits will be apparent.

Correction on PI in the USA. The reason PI was never fitted to USA TR's was purely on price, it made the car sell price above BL's target sell price and the dealers did not want it because it was too complicated in operation. This info came from the BL's USA marketing manager. BL even considered triple DCOE's!

Bruce.

[DRD]

I've trodden the same route myself recently and I would caution at trying to do bits of the engine rather than the whole job. You end up wasting a lot of money!

IMO the best way, if you want to keep the original engine, is to have the engine completely rebuilt to a fast road spec, gas-flowed head with a higher CR, new fast road cam etc etc. You will also need improved breathing/manifold/exhaust and get the distributor rebuilt to match the engine. Finally whatever fuel system you decide to use such as HS6 SU's or Webers need setting up on a rolling road by someone who knows what they are doing.

It isn't going to be cheap but I ended up with about 145HP using SU's. You could get more with racier cams but then you loose tractability at slower speeds and the engine has a very lumpy idle.

Cheers Daz

[DRD]

On 4/25/2006 at 12:36 PM, graham.dillaway said:

 

Thought I would add my personal experience to this discussion

I have an original US spec car This is what I did to uprate the engine/performance

 

1: Fitted SU carbs on BAE needles

2: fitted K&N filters

3: Skimmed the head 125 thou to take it up to 10.5 cr

4: Fitted tubular exhaust manifold 3:2

5: Fitted twin sports exhaust system

6: Fitted uprated camshaft BP370

7: Modified the distibutor curve to PI spec

 

After I had done this I had the car tuned on a rolling road and got 150 BHP

 

regards Graham

Hi Graham, I've got a similar spec engine and am surprised your SU needles are rich enough. I was using those before my rebuild and the car was very lean at the top end after the rebuild. I had the car setup by Tom Airey on his rolling road and he used BBA needles.

Cheers Daz

[Nigel Triumph]

On 4/24/2006 at 3:45 AM, Guest andythompson said:

Depends if the engine is fresh or not...

 

Depends if you want the injection set up or not...

 

If the motor is reasonably fresh the easiest, cheapest power would be the following...

 

1.Fit HS6 Carbs... you may need a saloon manifold for the linkage and modded throttle cable

 

2.You need to lift the head and put in a decent camshaft + new followers... a Chris Witor custom cam is an excellent compromise.. bit less overlap than a TR5 but a bit more lift on the inlets... good for carbs

 

http://www.chriswitor.com/Chris_Witor_Price_List.pdf

 

3..You should get a late head 219016 or 219021 and skim it to 3.400" thickness ie 9.5:1 CR.

 

You will need to run premium unleaded

 

4.If you have the spare cash.. fit bigger inlets (37.75mm or 38mm) and fit unleaded seats and standard exhaust valves.

3 angle cut on seats.. no other gas flow work really necessary.

 

5. Get a 6-3-1 Alternate Pulse extractor exhaust

 

6. Distributor will need rebuilding to give less initial advance

 

Bolt it all together and find a decent Dyno that can tune SU's... this should get you 140-150bhp no problem.

 

If the engine is tired the same applies but you will need a rebuilt bottom end.

 

Do the same but fit injection or webers and you would make about 150-160bhp but spend a lot more money

That's exactly the spec I chose when rebuilding a 2500S saloon engine for my GT6 last year, including Chris Witor's excellent CW3021 camshaft. In addition, the engine is balanced and uses a GT6 flywheel, weighing only 8Kg. My starting point 2500S engine was rated at 105bhp by the factory, so very similar to the US-spec TR6.

 I can't yet give a dyno figure, it was going for a rolling road session when lockdown started. Subjectively, the engine feels very strong throughout the rev range now it's run in. Compared to my CP series TR6, the tuned GT6 doesn't have quite the same punch of torque from around 1,500rpm but from 2,500rpm onwards, it's hard to notice any performance difference. In the lighter GT6, it absolutely flies and top gear acceleration is astonishing!

I would not advocate the expense of Webers for road use, SU HS6 carbs are perfectly adequate. I'm sure Webers are fine instruments but if my budget had stretched to the cost of triple Webers, I would have chosen EFi.

Nigel

[Andy Moltu]

39 minutes ago, astontr6 said:

Correction on PI in the USA. The reason PI was never fitted to USA TR's was purely on price, it made the car sell price above BL's target sell price and the dealers did not want it because it was too complicated in operation. This info came from the BL's USA marketing manager. BL even considered triple DCOE's!

Bruce.

There were also concerns about the looming emmission legislation in California and other states which would have added further to the cost of supplying the Lucas injected TR5 & 6 in the states. Hence the TR250 designation emphasising the 2.5 L engine in the watered down version of the TR5 suplied to the States.

The Lucas PI could have been modified to meet the legislation but would have been more complicated and costly to make. (We have all come across metering units with latitude compensators supplied in small numbers to high altitude markets rather than what they did in the main which was to simply weaken the mixture)