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Race Clutch - TR4


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I am looking for a high performance clutch with a sprung centre (for the odd occasion on the road) rather than a paddle clutch. The only one I have found so far is an 8.5" Helix, which I currently use & works well. The new engine should deliver 200bhp+ which is at the top of the helix's capability. Any one tried any other?

Nick

 

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Nick that is some power number!!! A John Wood or TRE lump? You do hear people say there engine can make number approaching that but I'd take it with a pinch of salt unless you have roller numbers from a recently calibrated RR. Is it an fia 87mm job, looks like it from the little pic.

 

Anyway I have run a Quartermaster 7.25" rally clutch in my 4 racer, with and organic clutch, spot on for the road or track (not like the sintered twin job in my TR6 (not ideal for the road).

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"unless you have roller numbers from a recently calibrated RR. Is it an fia 87mm job"

I should doubt any 4 cyl TR engine is giving 200 hp on a Rolling road linking your comments together, even a Dyno figure of that would be an achievement.

 

Mick Richards

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Keith Files has said that TRE and JW are claiming over 210 for 87mm engines now. That is 99bhp per litre, I just do not see that as possible in on a none cross flow old fire pump lump.

 

Hi Mike,

 

I have a fresh engine, with my trick Ali head (stuff in there you cannot do to dis one and from a bare casting so clever mods ???? By top mini Miglia guy, new rods, dummy main crank and more. I will be happy with 190 when run in. Plus my car is 100kg lighter than fia at least.

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Bhp figures are what you brag about in the pub.

 

Different rolling roads, dyno's give varying figures.

 

What matters is how it goes on the circuit.

 

As the saying goes....

 

When the flag drops, the bull$hit stops

 

????

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Nick,

Sounds as if you already have a clutch friction plate fitted and want another because it is wearing.

Consider having the old one recovered? And perhaps with an alternative material?

 

There may be other companies that can offer this service, but I have used Questmead: http://www.questmead.co.uk/ who were happy to discuss my needs on the phone, or by any other media.

 

John

(No association other than customer)

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Looking at simulations: with a 87mm bore, 1..630 intake valve, and a head that flows a little better than what TRE has sold (PB ported head), and a 7200rpm peak, you would need .645"+ lift at the valve. No way they are pulling that off without a custom billet cam core and rocker ratios over 1:6. This also assumes a compression ratio of 12.5:1 - which I don't think is often seen in Europe due to lack of good race gas.

 

I've always been skeptical of what some of the European tuners have posted HP wise. Some of what I've seen is they are off by 20-30hp to what they claim.

 

Peak power is pretty much a function of how those heads are ported at the MCSA. As the bore increases, the lower the peak rpm will be with the same head bolted on.

 

100hp/L is certainly doable out of the Triumph lump, but it's not getting done with anything you can buy off the shelf, requires a better modified head than what you typically will have done, and requires quite a bit of compression and rpm.

 

In the States, the very best A-Series builder is making 110hp/L at the flyhweel (measured on calibrated engine dynos, not chassis dynos and "back calculating"). He also has the airflow capacity to see 115-120hp/L, but the valvetrain can't get the valves lifted to the point to support that airflow in the lift curve. To get there will take tens of thousands of dollars and doing a lot of work on a Spintron.

 

Also, Chris, torque doesn't win races, the most average horsepower across your operating range does ;)

 

Here is how a proper TR4 race engine runs ;)

https://m.youtube.com/watch?v=my65yxWENFE

 

The other cars at that particular race have about 175-180bhp - similar builds to what Chris has.

Edited by hoffman900
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