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130BHP Engine - Recommendations

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Hi Forum!

 

My TR4A Engine is basically sound. About to put on the narrow belt conversion / alternator / electric fan. Already have a 123 ignition system and K&N air filters

 

My basic question is - if I wanted to liberate a few more HP - up to about 130, what is the best way to do this , whilst still retaining the tractability of the engine and not stressing anything way more than advisable.

 

I'm thinking that 89mm Liners and pistons are a good idea - are they? does a performance manifold make much difference? what else?

 

Advise away Chaps!

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Whers's this 130 hp ? Flywheel or rear wheels ? The original engines I believe we're dyno'd and therefore their figures are flywheel which as a rule of thumb we allow 15% more for rear wheel drive losses. Now if 130 flywheel I s required that is reasonably reached with maybe a fast road cam gently reworked head 89mm pistons and performance exhaust system. The standard carbs will cope fine.

Is that the sort of expenditure you had in mind ?

 

Mick Richards

Edited by Motorsport Mickey

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Nick,

 

With TR engines it is important to match and balance all the engine 'upgrades' to achieve your desired result.

Unlike with MG's, you can't just keep bolting on stuff and getting more HP every time.

 

I agree with Mick - standard carbs are absolutely fine but money should be spent balancing the rotating masses when you rebuild the engine.

Likewise, if the block is really clean you don't need any fancy cooling upgrades, and certainly not an oil cooler.

Spend any spare money on the head and making sure it is all bolted together really carefully.

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I was referring to 130bhp at the flywheel (I think it was 104 standard?)

 

So breathing and a larger bore seemed a good idea- be interesting to hear from others on here who have done this

 

I'll be absolutely honest in that I have no idea how much a rebuild will cost - I can cost the various upgrades, but the actual work (which I know I couldn't do) I have no idea. I do have a reasonable budget (probably not enough :-)

 

do the rocker upgrades give any advantages?

 

I'm not looking to get it all done in one go - so won't be adding bits hoping for a couple of HP each time.

 

Nick

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"do the rocker upgrades give any advantages"

 

No, you need to be using lots of revs for roller rockers (if that's what you refer to) to be of benefit. The 89mm pistons will give loads of mid range torque without you having to rev the nuts off it, and a good cam will allow the breathing to benefit and help the bigger pistons and the reworked cylinder head release more power and torque which the performance headers and exhaust can then allow to breathe.

 

You have to be careful trying for fast road spec engines, it's very easy to go too far and end up with a half race spec engine that needs 3000+ revs everywhere to keep it on cam. The standard carbs either SU or Strombergs will help deliver the mid range torque and allow the use of the lower revs for the car to be "trickled" along when needed. As good as Webers are, apart from the cost the standard carbs will handle power up to 160 and they are for free.

 

Mick Richards

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" I'm not looking to get it all done in one go "

 

It doesn't make a great deal of economic sense to upgrade in easy stages . . . . . you'll find yourself duplicating labour costs to no real benefit !

 

From my past experience, you could do a lot worse than to have a chat with Peter Burgess, whose cylinder head work is exceptional - and he has decades of experience with TR engines.

 

Mick Richards is too modest to bother mentioning just how many TR sprint, hillclimb, race and championship wins he achieved in years gone by, aided I might add by Peter Burgess' head work.

 

SUs will do very nicely for a good quick road engine, Webers are needless expense for the sort of performance you are seeking, just bling factor.

 

Fully balanced engine, 89mm pistons, Burgess head, a decent cam, rebuilt dissie and carbs to suit, and a decent exhaust system . . . . .

 

Cheers

 

Alec

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Nick,

 

With the right connections, and if you do some legwork yourself, the whole exercise can cost you around £3k.

 

Go to the usual suspects and you need double that or more.

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Having done the above and some I carefully run in my new engine on the SU"s and then proceeded to give it some beans. It wasn't quite what I had hoped it would be, but impressive none the less.

 

After a short while I then moved to Webers and the difference is like night and day - they were carefully set up by a man who knows on a rolling road and I have retained the low down pull, torquey mid range with a real pull up to the red line. The engine bay looks better and the car sounds so much better too.

 

I really do not understand the negativity towards Webers and surely a Venturi per cylinder is the preferred option.

 

I'm no expert but if you would like to come and have a ride in my car you'll see what I mean.

 

I didn't consider the cost of the Webers over SU's one bit and I ran my SU's for 5 years quite happily before the major engine work.

Edited by Mark1965TR4aBRG

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I really do not understand the negativity towards Webers and surely a Venturi per cylinder is the preferred option.

 

 

In my opinion often bad setup WEBERs are compared with proper set SUs.

So the result is not like it could be.

How often did I drive a TR6 with DCOE that smells awfull after fuel!

Also visually there is the greatest difference when an engine is tuned like that.

 

Many people try to save money and buy second hand DCOE and try to

save the cost for the metering parts inside. Starting with them I had to buy

a little set in the range of 1000GBP to have something to swap.

 

Here in Germany its very common to tune the TR6 with Stromberg or SU

and a head rework, increase compression and a 280 or 290 degree cam.

Those engines perform quite well and if setup carefully they will idle still

acceptable but what you always feel is the trouble around 2000 rpm.

The engine runs not that smooth like it could and often idle is really bad.

The engine starts more idling on temperature with very low idle when cold

and running high when hot. Also the drop in rpm when lights are switched

on or other electric is needed is much bigger than before.

 

All that is gone with proper set Weber. The idle is perfect, can be seen when

race engines idle. Also at part throttle there is a huge benefit with the separated

inlet runners that do not interfear any more.

 

The price is high, the setup needs skill but the result can be worth all that.

 

Look at other 4 cylinders, how did the companies do that ex works?

The BMW 2002 starts with one carb at 100 HP, the TI has 120 with 4 carbs

and for 130 they employ the fuel injection.

Their tuning is done pretty similar to what is invisaged here!!!!

 

Alfa Romeo just from the beginning employes 4 carbs for their 2 litres to

perform 130 HP.

 

Mercedes Benz unses 4 carbs on the 190 SL to get 115 HP.

 

They would not have done so if the power can be achieved that smooth

with less money and less carbs. Especially because at that time German

Solex was a company to offer these carbs with two stages what they had

developed to perfection and are in use in many German cars of that days.

 

So its possible and cheaper to obtain the 130HP with SU or Stromberg

but its not the best way in my opinion (what should I say else as I like

the EFI as a similar way to achieve individual inlet runners).......

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" I'm not looking to get it all done in one go "

 

It doesn't make a great deal of economic sense to upgrade in easy stages . . . . . you'll find yourself duplicating labour costs to no real benefit !

 

From my past experience, you could do a lot worse than to have a chat with Peter Burgess, whose cylinder head work is exceptional - and he has decades of experience with TR engines.

 

Mick Richards is too modest to bother mentioning just how many TR sprint, hillclimb, race and championship wins he achieved in years gone by, aided I might add by Peter Burgess' head work.

 

SUs will do very nicely for a good quick road engine, Webers are needless expense for the sort of performance you are seeking, just bling factor.

 

Fully balanced engine, 89mm pistons, Burgess head, a decent cam, rebuilt dissie and carbs to suit, and a decent exhaust system . . . . .

 

Cheers

 

Alec

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So what is the best cam to fit at this level of tune?

Tony

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Thanks for all the replies and advice!

 

sorry for my typo - I most definitely AM going to get it all done in one go!

 

Paul Harvey - Legwork I'm happy with, right connections - I have none :(

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I doubt there is a 'best' cam . . . . . it's a decision to be made by the owner in conjunction with the individual engine builder.

 

Ultimately one choke per cylinder is always likely to prove superior to a pair of single choke carbs feeding four cylinders, agreed, but it is not essential for a 4-pot Triumph, wet liner or slant, if a power output hike in the order of 20-40% is desired.

 

The difference between rebuilding a pair of existing SUs to suit, tweaking the existing manifold to match, and a brace of new Webers plus manifolds . . . . . is the difference between a couple of hundred quid and in excess of a grand.

 

That additional £800 is the difference between just affordable and pipe dream for many a TR enthusiast . . . . . TR2, 3, 4 and 7 alike.

 

Cheers

 

Alec

Edited by Alec Pringle

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But the sound a Webered 4 pot makes is worth every penny spent on buying and setting up!!

Cheers Rob

The right size Webers are a delightful indulgence for those who can afford them.

The wrong Webers are a pain in the proverbial.

 

Neither will run without an engine.

Edited by Paul Harvey

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I can only endorse the recommendation to consult Peter Burgess.He has all the experience and knowledge you seek.He is also a very nice,helpful guy.

Good luck Tom

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If you are doing it in stages - the last stage would be webers as they are a bolt on job & the SU's when well set up are pretty good for a fraction of the cost.

 

Everything else is inside the engine and something you won't touch that often once done.

 

Most wouldn't advocate going over 89mm pistons/liners.

Lighten your flywheel and balance the bottom end. Reduces the chances of the crank breaking when using the power!

 

Fast road cam. Unlike the 6 cylinder TRs which can carry a pretty wild cam without losing too much tractablilty, building a screamer of an engine for road use is a recipe for dissatisfaction.

Working the head is generally power gain for nothing other than cash and allows he other mods to head & exhaust to work better. At the very least the exhaust valve seats may need fitting to save on unleaded additives if you haven't done so already.

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I have 87mm pistons and liners in my rebuilt engine, along with a "fast road" cam with the following specifications.

 

Intake: opens 20 degrees BTDC; closes 60 degrees ABDC
Exhaust: opens 60 degrees BBDC; closes 20 degrees ATDC
Duration: 260 degrees
Cam lift: 0.290"
Valve lift: 0.440"
Valve settings (hot): intake 0.012" - 0.014"; exhaust 0.014" - 0.016"
(in practice 0.014" warm, not necessarily hot, for both)
I'm not remotely near 130 bhp flywheel, but the car scoots just fine and will burble along slowly or run to the redline beautifully. Standard SU H6 AUC878 carbs.
The car ran hotternhell for the first thousand or two miles after the rebuild. Seems to have settled down now as it's loosened up. The 87mm bore has probably added more heat to the system than the original 83mm setup. Consider cooling needs if you go up to 89mm.

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