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Hi all

Looking to convert my car so it runs on unleaded petrol. Whilst I’ve got the head off to do this conversion are there other simple modifications I can do to increase the power from the 150bhp engine? For example bigger valves and new headers be worth doing? Or any other suggestions?

Thanks,

Nige.

 

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There are some casting numbers and another number at the front r/h side stamped into the head, these numbers can tell us what you have at present, will need also the overall thickness of the head, and also perhaps the capacity of the combustion chamber, from this I think recommendations can then be given.

Is it a PI or carb engine?  CP or CR?

Need to know what you actually have at present.

John

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Not much to do.

If you do not expect fuel pinking you can shave the head a little bit.

As you will loose some power from the valve inserts you can grind the inlet and outlet to compensate for that and make the step from runner to insert a little bit smoother.

The combustion chamber around the valves and around the plug can be grinded carefully not taken too much away, not more than the cylinder bore shows.

The exhaust area around the valve guide is pretty tight and can be grinded a little bit right and left from guide,

Valve seats can get the famous three angle valve job but all in all you always have to take care not to make the inserts to wide open, that they will pop out.

Good exhaust header at this stage will give around 3HP over the stock max, so not worth the effort.

The fan will catch around 3-5 Hp and maybe removed for the electric fan.

 

Do not expect too much. If you set the MU properly to AFR 12.7 and do all the things you will get around 150 - 155 HP because orginally the CP had only 136 and so you can have a nice increase of 14 hp in reality.

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That guru of engine developers, David Vizard, gave us "Tuning Standard Triumphs over 1600cc", and the details are  availble online at: http://auskellian.com/paul/links_files/David Vizard-Tuning Standard Triumph.pdf    See Chapter 6.   

If you are willing to make sure that you only use 99 octane fuel (Shell V-power - BP Ultimate is 97-98 RON) then a Compression Ratio of 10.5:1 will not pink.    To ensure that any skim you do does not exceed that CR, then it's essential to measure the combustion chamber volume by buretting.     Online calcaulators cannot take new valve seats and flow mods a la Vizard into account.    May I modestly refer you to my article on "How to Do It", on Sideways?  http://sideways-technologies.co.uk/forums/index.php?/topic/7551-how-to-raise-the-compression-ratio-safely-and-effectively/

Just doing the head won't allow the optimum from the engine, so ensure that your fuel supply is up to the new set-up, an Metering unit rebuild by a reputable supplier, who will need to know what you are doing to the rest of the engine, will not cost that much, and the fuel pump - I won't get into Lucas vs. Bosch!      An 'extractor' exhaust manifold, with 6-3-1 headers, will allow your improved head to breath.

Good luck!

John

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52 minutes ago, john.r.davies said:

 

If you are willing to make sure that you only use 99 octane fuel (Shell V-power - BP Ultimate is 97-98 RON) then a Compression Ratio of 10.5:1 will not pink.    To ensure that any skim you do does not exceed that CR, then it's essential to measure the combustion chamber volume by buretting.   

+1 for Shell V-Power, my engine (CR of 9.8) runs really well on it. Anything else is noticeably worse, even with an octane improver additive.

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19 hours ago, nigelcurry@hotmail.co.uk said:

Hi all

Looking to convert my car so it runs on unleaded petrol. Whilst I’ve got the head off to do this conversion are there other simple modifications I can do to increase the power from the 150bhp engine? For example bigger valves and new headers be worth doing? Or any other suggestions?

Thanks,

Nige.

 

Hi Nige!

Get a copy of BL's Special Tuning manual ISBN978-1-78318-001-1 written by Kastner in the USA. Brooklands Books Ltd sell this book here in the UK.

Bruce. 

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A high-lift cam, re-worked cylinder head, decent extractor manifold, with appropriate exhaust system, should produce a decent rise in power. Presume your car is fitted with Lucas PI ?  That will be the only limiting factor for ultimate power, where top-end fueling requirements can be tricky to get the most from a serious cam.

Cheers.

 

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5 hours ago, Jctr6EFI72 said:

What about fast road camshaft?

The above booklet recommends and S2 cam for road use which is the same as an SAH 357 cam + head mods + exhaust header+ exhaust system.

Bruce. 

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There are much wilder cams available than the CP ( or S2 for that matter ) and the difference is dramatic but they are fraught with corollary requirements and degraded longevity prospects. I have one such, 0.504" lift / 292 degrees duration but it's in a concours car which sees ~ 500 miles/year, ~ 10 per outing. 

Head work can make a nice difference, a guess would be ~10 BHP and an optimized exhaust system likewise at best.

My next, and probably last engine will use a CP cam, Peter Burgess head, forged pistons and Carillo super light, unbreakable rods. It should go to 6500 rpm without worry but won't break any records for power. It will likely be the smoothest and most bullet proof 6-pot TR engine on the planet, easily good for 150,000 blissful miles. At this rate I'll be 95 then. 

Of course it will have vintage Italian 40DCOEs.

 

Tom

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Alternatively you could always add a supercharger :-).

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1 hour ago, Tom Fremont said:

There are much wilder cams available than the CP ( or S2 for that matter ) and the difference is dramatic but they are fraught with corollary requirements and degraded longevity prospects. I have one such, 0.504" lift / 292 degrees duration but it's in a concours car which sees ~ 500 miles/year, ~ 10 per outing. 

Head work can make a nice difference, a guess would be ~10 BHP and an optimized exhaust system likewise at best.

My next, and probably last engine will use a CP cam, Peter Burgess head, forged pistons and Carillo super light, unbreakable rods. It should go to 6500 rpm without worry but won't break any records for power. It will likely be the smoothest and most bullet proof 6-pot TR engine on the planet, easily good for 150,000 blissful miles. At this rate I'll be 95 then. 

Of course it will have vintage Italian 40DCOEs.

 

Tom

STD crank? Unbraced block? Be careful 

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7 minutes ago, ntc said:

STD crank? Unbraced block? Be careful 

Affirmative - the crank will have 6 lbs less on its throws than the stock bits, alleviating the need for bracing up to that point. At least one notorious specialist in the UK claims the stock crank will hold to 7000 rpm, 500 rpm more than the stock pistons and these will be forged. 

I doubt I'll ever take it over 6000 anyway. 160 ( genuine ) BHP?

 

Tom

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On 9/14/2020 at 9:31 PM, astontr6 said:

Hi Nige!

Get a copy of BL's Special Tuning manual ISBN978-1-78318-001-1 written by Kastner in the USA. Brooklands Books Ltd sell this book here in the UK.

Bruce. 

There's also Kas Kastner's Triumph Preparation Handbook. I don't think it's the same as the one Bruce suggested. It's a really informative book. Even if you're not doing all the work yourself (porting a head using a Dremel, anyone?!), it will help with your discussions with those you're paying to do it. It's only available as a pdf direct from the man himself - http://www.kaskastner.com/kasbooks.html

John

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4 hours ago, JohnC said:

There's also Kas Kastner's Triumph Preparation Handbook. I don't think it's the same as the one Bruce suggested. It's a really informative book. Even if you're not doing all the work yourself (porting a head using a Dremel, anyone?!), it will help with your discussions with those you're paying to do it. It's only available as a pdf direct from the man himself - http://www.kaskastner.com/kasbooks.html

John

The book that you describe is the same book as I have stated but it was sold under 2 different names I have one copy that is 50 years old and the other is 5 years old and is still in print by Brooklands Books here in the UK. SAH when they were in business here in the UK were a ST garage for BL and produced tuning kits and parts for all BL cars. They based there TR6 kits on this booklet and my car was fitted with one!

Bruce.

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I am sure we have been here before a few times.

The important thing to ask yourself is what you want from the car. For example..

Do you want a car that revs freely to heady levels of 6000 rpm but potentially isn't as tractable at low revs and perhaps has a shorter service life.

Or do you want to focus on lower end torque sacrificing the high end buzz?

It is also perhaps working with the natural talents of the engine. The Triumph 6 has a long stroke so aligned to low end than high. 

I've had triumph engines optimised for both and having a revy engine is fab but for my use (which is more endurance rallies like 10CR and RBRR) I like good low to mid range torque for overtaking and punching up mountain passes and need it to be tractable at low speeds. It is also good if it is at least a bit frugal. The Moss Supercharger kit fits nicely into here.

In comparison, I currently have an MG midget with a modern short-stroke 16 valve engine. It is very revy and has a power band that extends beyond 7000 rpm. It is huge fun if you need an adrenaline boost but may not be the best for longer runs.

It is worth considering all this else you may end up with a car that you may not enjoy driving:-)

Cheers

Tim

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As NCT says 180bhp is about the upper end of what can be achieved for a road car without compromising drivalbility and reliability/longevity not to mention costs which also tend to escalate beyond this point too.

That said some of the race cars are chucking out 250bhp+ although what they would be like to drive on the road and how much fuel they need and rebuild intervals are another thing.

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I do enjoy participating in these type of threads :)

Triumph 6 cyl

170bhp RWP and circa 200 BHP @ the flywheel & approx 200lbs ft is absolutely achievable, and entirely reliable including driving hard, with regularity. The standard crank WILL take it, combined with a good quality piston (AE/Mahle), etc. I am not sure about the standard rods, perhaps they will be OK, but in my case, I have a set of Carrillo rods.

Important the the entire rotating assembly is balanced properly (flywheel, clutch cover, rods, crank, pistons, cam & crank pulley). 

A Newman cam (hybrid) with their steel EN40 followers is a good place to start. A decent exhaust manifold (Tony Law) mated to a 2.5" (2.25" would also be OK)-Pheonix big bore. 2.5" would be a bespoke system, which are not as loud or expensive as some folks may think ? Race systems are available from places like TRE, but designed for non O/D cars. The shape is slightly different due o/d unit, perhaps they can be manipulated to fit an o/d car ?

The list of other parts would take some time to list, but if built nicely and carefully, coupled to Lucas PI, will give you a tractable car from 1000-6500RPM, and idle smoother than the earlier CP cars.

I have also driven a tripple webered 6 with a race cam, installed on a +0.80" bore block, with forged pistons and Carrillo rods. This had a lot of duration (326) and huge valve lift. It also requires the cam followers bore enlarging to accept Ford GT40 cam followers. (0.875"), otherwise the lobes will run off the sides of STD ones. A pushrod change is also required. It was very tractable from idle again, despite its nature, and produced a unreal torque plot from 2000-7000RPM.

 

I will soon be in the process of trying a Newman PH5 race cam on EFI, so will report back my findings.

 

Cheers.

 

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12 minutes ago, TRTOM2498PI said:

I do enjoy participating in these type of threads :)

Triumph 6 cyl

170bhp RWP and circa 200 BHP @ the flywheel & approx 200lbs ft is absolutely achievable, and entirely reliable including driving hard, with regularity. The standard crank WILL take it, combined with a good quality piston (AE/Mahle), etc. I am not sure about the standard rods, perhaps they will be OK, but in my case, I have a set of Carrillo rods.

Important the the entire rotating assembly is balanced properly (flywheel, clutch cover, rods, crank, pistons, cam & crank pulley). 

A Newman cam (hybrid) with their steel EN40 followers is a good place to start. A decent exhaust manifold (Tony Law) mated to a 2.5" (2.25" would also be OK)-Pheonix big bore. 2.5" would be a bespoke system, which are not as loud or expensive as some folks may think ? Race systems are available from places like TRE, but designed for non O/D cars. The shape is slightly different due o/d unit, perhaps they can be manipulated to fit an o/d car ?

The list of other parts would take some time to list, but if built nicely and carefully, coupled to Lucas PI, will give you a tractable car from 1000-6500RPM, and idle smoother than the earlier CP cars.

I have also driven a tripple webered 6 with a race cam, installed on a +0.80" bore block, with forged pistons and Carrillo rods. This had a lot of duration (326) and huge valve lift. It also requires the cam followers bore enlarging to accept Ford GT40 cam followers. (0.875"), otherwise the lobes will run off the sides of STD ones. A pushrod change is also required. It was very tractable from idle again, despite its nature, and produced a unreal torque plot from 2000-7000RPM.

 

I will soon be in the process of trying a Newman PH5 race cam on EFI, so will report back my findings.

 

Cheers.

 

Sounds impressive..

what carburation are you using? Also what revs are you getting peak torque?

Cheers

Tim

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On 9/16/2020 at 5:34 PM, astontr6 said:

The book that you describe is the same book as I have stated but it was sold under 2 different names I have one copy that is 50 years old and the other is 5 years old and is still in print by Brooklands Books here in the UK. SAH when they were in business here in the UK were a ST garage for BL and produced tuning kits and parts for all BL cars. They based there TR6 kits on this booklet and my car was fitted with one!

Bruce.

Thanks Bruce. I did wonder if it was the same under a different name. BTW here's what Kas had to say when I dropped him a note a few years ago: "Actually the download version is a ton better than the paper book which was done way over 10 years ago. You've made a good choice to start with.  Good luck with it all."

I have no idea what has been changed/updated.

John

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