Brabham BT35/Lotus Twincam

[smo17003]

This video popped up on my Youtube today https://youtu.be/WHO5K62TGLs?si=uDWNsgO994qmmxBO

Watching it got me wondering what was the fastest Twincam powered car that was produced? I thought someone here would be bound to know. Good video btw.

Mike

[StressCraxx]

Did some searching.

On water - 11/25/67 Class "L" Parker, AZ Harvey Stuska L-64 Metisse hydroplane Lotus-Ford/Stuska 113.374
https://www.vintagehydroplanes.com/apba ... ydros.html
I knew Stuska in Denver Colorado. He built dynos and built the Twincam with Lucas Tecalmet injection.

On pavement - likely the Piper GTR 1300cc Twincam. Clocked on the Mulsanne Straight at 164mph.
https://forums.autosport.com/topic/27885-piper-gtr/
https://www.ultimatecarpage.com/car/4134/Piper-GTR.html

[shynsy]

I wonder whether there has ever been a lotus twincam powered car run at bonneville?
Tim

[trw99]

The late, great Brian Hart developed a race version of the Lotus Twin Cam engine - the 416-B; by as early as 1972 he was getting 190 bhp out of it. Some were small valve versions (1.625" intake & 1.375" exhaust), most had big valves (1.69" intake & 1.44" exhaust); some had iron blocks, some had alloy. At first they breathed through twin Weber 40 or 45 DCOEs: with short trumpets, maximum revs were 8500; for the alloy block version the maximum revs were 9250 with long trumpets.

Later he developed the Lucas fuel injection system for the engine. Hart 416-B engines were popular in the USA and Australia for the US Formula B and Australian F2 during the 1970s. Engine spec's for a 1973 416-B with iron block were 200 BHP min @ 8500 RPM, torque of 130 lbs/ft max @ 7500 RPM; for a 1974 with an alloy block they produced 200 BHP min @ 8500 RPM, torque of 125 lbs/ ft @ 8500 RPM. The engine was fitted as original to the Brabham BT40.

In his book, Miles Wilkins wrote that ‘Hart managed to extract around 200 bhp from an all alloy block TC in 1974’.

Tim

[dunclentdr1]

I have a Nerus Silhouette, designed by ex Jim Clark race engineer Cedric Selzer, with a twin cam that produces 204bhp on a 2 litre alloy block, big valves and 45 Dellortos.

[trw99]

Very nice Duncan!

SressCrax's question starting this thread implied what was the most powerful twin cam engined car produced in period, hence my reply about the Hart, producing 200 bhp in the early 70s.

It got me thinking. Recalling the Austin A35s being raced at the Revival in the St Mary's Trophy sent me researching the power they produced now and back when new. The wee A Series BMC engine in the A35 ranged from 34 to 55 bhp during production. Then I found an A35 race car for sale now, huge twin SU carbs and producing 130bhp! (No wonder the Earl of March made his impassioned plea video warning on technical eligibility, aka cheating, before the start of this years Revival!).

I suspect that with current technology, machinery and materials significant gains can be made with know-how, close tolerance CNC milling and superior steel.

In other words, there is presumably the capability now to make significant horse power gains from a twin cam, which likely bear little resemblance to those that could be made back in the 1960s & 70s.

Tim

[pharriso]

In other words, there is presumably the capability now to make significant horse power gains from a twin cam, which likely bear little resemblance to those that could be made back in the 1960s & 70s.

Tim

I was talking with a racer at a SVRA meeting a few years ago who had a Lotus 23, stated he was getting 211hp on the dyno with slipper pistons, new SAS cylinder head etc. Not sure if it was 1558cc...

[StressCraxx]

200+HP is very impressive. It does tend to make for a "peaky" driving experience. The SAS race heads are very good and correct the weaknesses of the Lotus produced heads.

The last rebuild on my 23B was in 2019 by Jay Ivey. It made 178HP on an original Lotus head.

I agree with Lord March.

[shynsy]

The use of modern tech seems to be rampant in classic racing. Kinda Don't blame them. Adrian Newey's lightweight E type and lotus 49 sound completely different to any of the others. Seem to well as well.
When we chat to the mechanics at the le mans classic and ask if their car is original spec they just look at us if we are fools.
I find it kinda interesting to see just how far old tech can be pushed. But my lines are drawn with not using standard fuel systems and non standard blocks and heads etc. In the era, things like cams, conrods, pistons, cranks and fasteners were pretty much fair game.
Tim