TR6 rolling road results

[Ogrodz]

Hi I am a new TR6 owner. My car is a US conversion to RHD and has triple webers. I think the engine block has been re-bored out to slightly more than 2500 - possibly 2800. I noticed some stuttering on acceleration so set about fixing it - starting with re-placing the FACEL fuel pump below the fuel tank and vertically in the boot (it was horizontally mounted). Then with the excellent services of Northampton Motorsport, addressing a sloppy throttle linkage which was not opening all of the carbs in unison and fettling the carbs to an optimum configuration as measured on a rolling road. The result - I am getting Engine Trq max = 154.5 and Engine Pwr max = 147.2. 

Simple question - how does this sound / compare? The car was first registered in 1976.

[Motorsport Mickey]

Hi Ogrodz,

Welcome to the forum, we often post with our first names also...makes it easier to talk between us.

Sounds good rolling road results, but they do vary around the Uk, maybe we know the road or operators ? and of course the revs when these figures were achieved will help to assess how the engines delivering.

Mick Richards

[Ogrodz]

Hi Mick

Eng Pwr max = 147.2  was at 5490RPM and 111mph. The Pwr curve is nice and linear with no bumps

Eng Trq max = 154.5 was at 4359RPM and 88mph. The Trq curve is pretty flat

The rolling road was at Northampton Motorsport - STP corrected flywheel power vs RPM

Stefan

 

[Ogrodz]

Here is a picture of my TR6 for the record.

 

[David Solloway]

8 minutes ago, Ogrodz said:

Here is a picture of my TR6 for the record.

 

I would be disappointed with the results. Big increase from American spec but it could do much more, perhaps the cam hasn’t been changed 

[Ogrodz]

What would you be happy with? What could I expect if I tried...

[harrytr5]

Love the look of your TR6 Stefan.

You must be proud of that.

Regards Harry TR5 Nutter

 

[FatJon]

147 at the wheels is a good result especially at 5500 RPM, that’s way better than a standard PI. You could get a bit more with a hotter cam but it may be less tractable and the standard crank is not noted for enjoying high RPM.

[FatJon]

And I love those wheels!

[CP26309]

Looks Racy and quite butch!

[Bill944T]

Eng Pwr max = 147.2  was at 5490RPM and 111mph

"147 at the wheels"

I didn't read it as at the wheels, as if it were, you'd probably be looking at 180 bhp at the engine flywheel.

Regards

Bill 

[TRTOM2498PI]

14 hours ago, Ogrodz said:

Hi I am a new TR6 owner. My car is a US conversion to RHD and has triple webers. I think the engine block has been re-bored out to slightly more than 2500 - possibly 2800. I noticed some stuttering on acceleration so set about fixing it - starting with re-placing the FACEL fuel pump below the fuel tank and vertically in the boot (it was horizontally mounted). Then with the excellent services of Northampton Motorsport, addressing a sloppy throttle linkage which was not opening all of the carbs in unison and fettling the carbs to an optimum configuration as measured on a rolling road. The result - I am getting Engine Trq max = 154.5 and Engine Pwr max = 147.2. 

Simple question - how does this sound / compare? The car was first registered in 1976.

I have seen your car before.  Derby area.

if you are on a 2.8L bore (more than +120 bore), I would question the reliability/head gasket at this level, plus wall thickness between the bores, sorry to digress.

Depending on the head, cam, & exhaust manifold, somewhere around 180bhp at the flywheel would be my guess.  Yes, RR do vary, but this is a typical figure seen on several rolling roads across the UK  I would also expect around 180lbs ft at this level too.

Do you know what cam it has fitted ?

Cheers.

 

[john.r.davies]

2800cc??  Is that possible?  Without offsetting the bores?

120 thou is 3mm! Surely there ain't enough metal between them, otherwise?

John

PS rolling roads often lie, and you just can't compare between them. but I have an alleged 160bhp from a +60 over bore >> 2600cc. 

[Ogrodz]

Thanks for all comments - much appreciated.

Yes, car is located in the Derby / Leics area. I am not sure of the final capacity (2800 does sound way too much) but the engine was completely rebuilt, rebored re-sleeved and the head worked on by Peter Burgess. Since the car has a sport 6 branch manifold (which usefully helps balance the fuel/air intake from the carbs) and big bore sports exhaust fitted, I assume that the cam will also have been "uprated" although I don't have paperwork to confirm this. The full nut and bolt restoration is a testimony to the previous owner.

The car is still running too rich at the moment - I am hoping to improve airflow somehow (gauze covers on the intakes removed) which I think will also make a positive difference. The carburettor air intakes are right above a very hot exhaust manifold - everything does get very hot which can't be helping - so I am thinking of wrapping the exhaust to try and reduce the hot air. Any thoughts about this? Is there any other way of improving cold air flow here?

I am enjoying the journey so far...

[Tony]

I have a similar spec engine and the Webcon gauze filters knocked 5 BHP  off the total figure, not that I notice it and prefer to have some form of filtration.

[JochemsTR]

2 hours ago, john.r.davies said:

2800cc??  Is that possible?  Without offsetting the bores?

yes, rare but possible without offset. rare in the matter, the bores are ultrasonic inspected and have a good consistent wall after bore.

I have a 2.7 with close upto 190. 200 can be achieved with a good head.

Edited September 13, 2022 by JochemsTR

[FatJon]

42 minutes ago, Ogrodz said:

Thanks for all comments - much appreciated.

Yes, car is located in the Derby / Leics area. I am not sure of the final capacity (2800 does sound way too much) but the engine was completely rebuilt, rebored re-sleeved and the head worked on by Peter Burgess. Since the car has a sport 6 branch manifold (which usefully helps balance the fuel/air intake from the carbs) and big bore sports exhaust fitted, I assume that the cam will also have been "uprated" although I don't have paperwork to confirm this. The full nut and bolt restoration is a testimony to the previous owner.

The car is still running too rich at the moment - I am hoping to improve airflow somehow (gauze covers on the intakes removed) which I think will also make a positive difference. The carburettor air intakes are right above a very hot exhaust manifold - everything does get very hot which can't be helping - so I am thinking of wrapping the exhaust to try and reduce the hot air. Any thoughts about this? Is there any other way of improving cold air flow here?

I am enjoying the journey so far...

I have similar cold air problems. My Jenvey throttle bodies don't leave much space for a good plenum to get cold air to the intakes. I plan to get busy with my TIG welder over the winter and see what I can come up with but first I'm building a new all steel engine with forged pistons. I will also implement some heat shield between the exhaust manifold and the inlet manifold/plenum/throttle bodies. Maybe also some heat wrap on the exhaust manifold, I have had good results with that in the past. Every day more bits arrive on the doorstep. The pistons are due today and I'm hoping to be talking to a gentleman from Cambridge about a steel crank this afternoon. If I get 200 at the flywheel I will be very happy and I think that's plenty for a road going TR on the original engine. I don't want to end up with an unpleasant 100% full race engine, just a strong and reliable one with the power to "let it all out" on rare occasions with no worries about the chocolate crank.

[john.r.davies]

As those above will very well know, the internal combustion engine is a lazy beast.     It cannot be more than just over 50% efficient, even theoretically, and our old anchors are probably less than 40%.     The rest is lost as noise and HEAT, and the vast majority of that is expelled via the radiator.    So unless you can put that somewhere else than in front of the engine, the underbonnet area will always be very hot!

Once, I built a racing TRiumph Vitesse estate, so that I could put a radiator in the back.    It worked, not so well that I won any races, but well enough.  That car was so cold to drive, even on a sunny day!   Almost all the heat was going out of the back, nowhere near the driver sat.      

Also, I have in the past wrapped my tubular exhaust, with glass fibre tape.  I painted it with HiTemp, but it always looks ratty!   And eventually I took the wrap off.     The manifold beneath had alarming corrosion!     Instead of the usual red powdery rust, blue-black layers of metal spalled off the tubes in large, thick flakes!      I suppose that this was the "ferrous" form of iron oxide, less oxidised that the red "ferric" form we are so familiar with.

John

[Ogrodz]

17 hours ago, Bill944T said:

Eng Pwr max = 147.2  was at 5490RPM and 111mph

"147 at the wheels"

I didn't read it as at the wheels, as if it were, you'd probably be looking at 180 bhp at the engine flywheel.

Regards

Bill 

To be clear the original figures I quoted were engine (flywheel) measures as estimated by a Superflow rolling road - apologies if I wasn't clear in the first post:-

The max corrected HP at the wheels was 126.3HP (using STP correction). This was measured at 5433 RPM and 109.8 MPH.

The max corrected Torque at the wheels was 139.2 lb-ft (using STP correction). This was measured between 4291 - 4359 RPM and 86.8 - 88.1 MPH.

See the curves below. I would like to know how this compares - is there more potential?

 

 

[DRD]

2 hours ago, Ogrodz said:

To be clear the original figures I quoted were engine (flywheel) measures as estimated by a Superflow rolling road - apologies if I wasn't clear in the first post:-

The max corrected HP at the wheels was 126.3HP (using STP correction). This was measured at 5433 RPM and 109.8 MPH.

The max corrected Torque at the wheels was 139.2 lb-ft (using STP correction). This was measured between 4291 - 4359 RPM and 86.8 - 88.1 MPH.

See the curves below. I would like to know how this compares - is there more potential?

 

 

This is my printout from a RR run I had a few months ago. These are 'at the wheel 'values so the power seems similar to yours.

NB: The engine is a CMES Stage 2 engine, with a ported & flowed head and high lift/duration cam etc.

Edited September 13, 2022 by DRD

[FatJon]

1 hour ago, Ogrodz said:

To be clear the original figures I quoted were engine (flywheel) measures as estimated by a Superflow rolling road - apologies if I wasn't clear in the first post:-

The max corrected HP at the wheels was 126.3HP (using STP correction). This was measured at 5433 RPM and 109.8 MPH.

The max corrected Torque at the wheels was 139.2 lb-ft (using STP correction). This was measured between 4291 - 4359 RPM and 86.8 - 88.1 MPH.

See the curves below. I would like to know how this compares - is there more potential?

 

 

I reckon there should be more to come then. The key once the mixture and timing are optimised might be cam and compression ratio. The US engines were low compression which helped emissions but lost a good bit of power. I certainly think triple webers and a good head could do better. Peter Burgess has an excellent reputation for head work but his head on an engine with badly tuned carbs, sub optimal ignition timing and a US cam is maybe where the problem lurks. 

 

[TRTOM2498PI]

3 hours ago, FatJon said:

I have similar cold air problems. My Jenvey throttle bodies don't leave much space for a good plenum to get cold air to the intakes. I plan to get busy with my TIG welder over the winter and see what I can come up with but first I'm building a new all steel engine with forged pistons. I will also implement some heat shield between the exhaust manifold and the inlet manifold/plenum/throttle bodies. Maybe also some heat wrap on the exhaust manifold, I have had good results with that in the past. Every day more bits arrive on the doorstep. The pistons are due today and I'm hoping to be talking to a gentleman from Cambridge about a steel crank this afternoon. If I get 200 at the flywheel I will be very happy and I think that's plenty for a road going TR on the original engine. I don't want to end up with an unpleasant 100% full race engine, just a strong and reliable one with the power to "let it all out" on rare occasions with no worries about the chocolate crank.

The standard crank (if fully balanced) along with: rods, pistons, flywheel, clutch cover & crank pulley), will take serious revs & not break.  11 years here & counting (80k + miles).

Ive seen a steel crank & standard crank that both received balancing at the same location. The stock one required less material removed over the steel one.

The standard cranks are very robust - FYI.

[FatJon]

The vibrations on the TR crank at high RPM are torsional. No amount balancing will fix it. It twists and untwists violently until either the crank breaks and destroys the engine if you’re lucky or the flywheel parts company from the crank due to elongated bolts/holes and a shearing off if you’re not lucky. I’m very attached to my feet and intend to stay that way. I hope you stay lucky.

[stuart]

27 minutes ago, FatJon said:

The vibrations on the TR crank at high RPM are torsional. No amount balancing will fix it. It twists and untwists violently until either the crank breaks and destroys the engine if you’re lucky or the flywheel parts company from the crank due to elongated bolts/holes and a shearing off if you’re not lucky. I’m very attached to my feet and intend to stay that way. I hope you stay lucky.

Scatter shield!

FWIW when I got my 4 there was several large holes in the bell housing where something had exited through!

Stuart.

[john.r.davies]

1 hour ago, FatJon said:

The vibrations on the TR crank at high RPM are torsional. No amount balancing will fix it. It twists and untwists violently until either the crank breaks and destroys the engine if you’re lucky or the flywheel parts company from the crank due to elongated bolts/holes and a shearing off if you’re not lucky. I’m very attached to my feet and intend to stay that way. I hope you stay lucky.

Which TR did you have in mind, Fat Jon?    As Torsional Vibration is my specialty I'm most interested!

However, if you refer to the six cylinder engine, I think that the speed limitation is down to the increased stroke over the original 2L.    This means that the acceleration forces on pistons and conrods exceed those that ordinary materials can withstand.

This will affect the crank, obviously, but torsional vibration is due to the regular impacts of the ignition stroke.   If they coincide with a resonant frequency of the crank, then that may be damaged, like an opera singer at a wine glass,or the Verrazano Bridge!

There are resonant frequencies below the 6K that an ordinary TR engine is limited to.   That is why Triumph fitted the crank damper to the front pulley, dampers that are all fifty years old, minimum, with many no longer able to damp out the excess vibrations.

The controversy continues about the Triumph four cylinder engine, and the use of electric fans, when the mechanical one MAY act as a damper.   I'm still looking for someone who will let me bolt my test equipment onto their TR4/3!

John

Edited September 13, 2022 by john.r.davies