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TR4 engine rebuild complete


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Well today is the day I finally got my rebuilt TR4 running the way I want it to

 

the last piece of the puzzle (in this case) was the fitting of dual 40mm Mikuni carbs to the new (1000 mile old) high spec motor

 

The motor was the last one built by a guy called Ted Davis who has lived Triumphs most of his life here in Brisbane and in his last years specialised in building wet liner high performance engines for Targa Tasmania cars & other nutters (like me). Unfortunately Ted got very ill half way through the process of building my engine and passed away at the end of September so hasnt seen the end product. But i reckon he built a pretty good motor.

 

specs

Moldex steel billet crank, cryogenically treated

14lb flywheel

balanced rods, cryogenically treated

89mm pistons & liners fro Ken Gillanders in the states

facet fuel pump

Wizard Cooling Aluminium radiator

ceramic coated dual 2 into 1 extractors

uprated water pump

high output oil pump

ported & flowed TR4A head

custom Tighe fast road cam

roller rockers

electronic rev limiter (6500 revs)

fiuel pressure limiter

inertia cutout switch

Mikuni 40mm slide carbies

 

so attached is the dyno print out with the Strombergs vs the Mikunis for anyone interested

 

Nothing else was changed

 

94hp at the wheels on the Strombergs, 106 with the mikunis, but the real difference in the 40 miles Ive done in it tonight is the torque band which stays about 20-40ft/lb higher than previously from4500 to 6000 revs

 

I just cant wait to get it on the track or a twisty mountain road where that torque and free revving will be magic

 

putting aside the investment in the whole motor rebuild, the Mikunis cost $1000 & bolt straight on, the rolling road including fitting & tuning the mikunis (& a little fettling of new linkages) cost $800 - so about 900quid all up in your money for a 12-13% power & performance increase

 

not for everyone i know but enough to keep me smiling for a long time

 

Graze

 

 

 

 

 

 

 

151126 - TR4 dyno.pdf

post-12376-0-22845600-1448538779_thumb.jpg

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Confused now,...I always understood that normally because of the maths involved in calculating the hp after measuring the torque the torque and hp lines will cross at 5252 rpm, not just one engine but ALL engines that exceed the 5252 revs area.

Sometimes I've seen graphs that don't show this and normally you can explain it by examining the scale on one side of the graph to the other where they show other information ie scale on left 275 scale on right 300 which misleadingly reduces the revs area where the line cross, however if you reference both the scales and redo the maths then they resume the link of 5252 rpm crossing (where graphs are concerned the 5252 area can "wander" about maybe a couple of hundred revs due to the graphics). However I can't see on this graph where there could be this problem, torque is shown in lb ft and I'm slightly mystified why it doesn't work, any ideas ?

 

Mick Richards

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thanks Roger

 

Mick

 

i dont know anything about the 5252 issue sorry - hope someone else can advise

 

Graeme

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Well, I am confused as my TR4 with similar tune but with twin Webers gives a much lower torque but a better HP of 113.4 @ 4800 rpm?

Am I missing something?

Also, I thought that if you up the cylinders/liners to 89mm then the capacity will rise. The capacity shown on the notes show only 2100 cc! I am on 86mm pistons/liners which I think gives around 2168cc?

Cheers.

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monty

 

you are right about the capacity

 

they just inputted the original 2.1L - it should be 2.4L

 

different cam and or different dyno might explain the power & torque differences?

 

Graeme

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G, with a spec like that, no wonder you are called 'Mr Spender'.

 

Look forward to the video (with sound track)

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monty

 

you are right about the capacity

 

they just inputted the original 2.1L - it should be 2.4L

 

different cam and or different dyno might explain the power & torque differences?

 

Graeme

 

Nope, whatever the camshaft or the dyno the magical formulae says that ALL engines that can exceed 5252 will show graphs where the hp and torque ( lb ft) cross over at 5252. Check it out on the web, try this for an intro into it.

 

http://trust-me-im-an-engineer.kinja.com/why-do-horsepower-and-torque-cross-at-5-252-rpm-1650651680

 

Loads of information on it, it's a function of the torque being measured and the hp being calculated from it by the revs. As I said sometimes where different sides of the same graph are used for different engines or cams for comparison it's one of the ways I always compare looking for the crossover to be in that same rev area, a quickcheck to make sure of like for like comparison.

 

ie: hrdp_0401_09_z%2Btorque_and_horsepower_g

 

As long as figures are lb ft and the rest of the info is scaled correctly the power and torque will always cross over at 5252, it's the maths, that's why it's puzzling me, I can't see why these don't ?

 

Mick Richards

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Looked back at the dyno figures on my car and the Torque /HP cross over at 5252

Gee I wish I had 300ft/lbs torque my car is only slightly more than half that!!

old saying "BHP sells engines Torque wins races"

Michael

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Mick, you are correct.

 

HP = Torque (Ft/Lbs) x Revs Divided by 5252. The lines cross because 5252/5252 =1

 

Rolling roads don't measure horsepower, they measure torque (turning force) and calculate HP from that.

 

 

Edit: Just realised I have simply repeated the info contained in your link!!!

Edited by Ragtag
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Looked back at the dyno figures on my car and the Torque /HP cross over at 5252

Gee I wish I had 300ft/lbs torque my car is only slightly more than half that!!

old saying "BHP sells engines Torque wins races"

Michael[/quote

Looked back at the dyno figures on my car and the Torque /HP cross over at 5252

Gee I wish I had 300ft/lbs torque my car is only slightly more than half that!!

old saying "BHP sells engines Torque wins races"

Michael

 

Yes Michael, 160 at best with 113.4hp, both @ the wheels on a well respected dyno.

Cheers.

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