camshafts Specification

[geni]

pour ma culture des arbres à cames
Je voudrais connaître les différents arbres à cames (ceux de l'Elan d'origine en général) et la puissance délivrée avec eux.
Toute bonne info est la bienvenue et pour la comparaison aussi
geni

[alan.barker]

Geni,
in English please

[geni]

:sorry but the translation is not automatic so I used GoogleTraduct and here it is

for my camshaft culture
I would like to know the different camshafts (the original Elan ones in general) and the power delivered with them.
Any good info is welcome and for comparison too
geni

[geni]

Surprise voila j'écris le texte en anglais et cela apparait en Français !
et j'ai bien fait l'effort suite a la demande répété mais alors que choisir en la solution idéale ?
geni


Surprise, here I am writing the text in English and it appears in French!
I have made the effort to do so, but what is the best solution?
geni

[rgh0]

The starting point for camshaft selection is what do you want to use the engine and car for ?

3 original Lotus camshafts std, S/E and Sprint if using these you would use the Sprint cam in any new engine build. The Sprint gives great torque and 126 hp with a 6500 rpm rev limit with the right carb settings and exhaust

Beyond that really two different types of cams are useful in most cars. Most other cams are old technology and not worth using

1. High lift (0.41 to 0.44 inch lift) and less than around 285 degree seat to seat as high performance road cams for around 160 to 170hp in a 1600 twink with a 7500 to 8000 rpm rev limit. Also better torque and power of about 150hp with a 6500 rpm rev limit of the standard bottom end in a 1600 cc twink

2. Higher lift 0.45 to 0.46 inch and less than 300 degrees seat to seat for a racing cam for around 180 to 190 hp in a 1600cc twink with a 8300 rpm rev limit

What they actually make in terms of torque band and max power depends on the specific cam and many many other engine details

You can get higher lift again to 0.50 inch with durations of around 320 degrees but these only really work in a light open wheeler where you can select gear ratios to suit the track and even then I am not sure the loss of torque is actually worth it for maybe another 10 hp at 9000 rpm in a 1600 twink and the resultant short engine life at these revs.

The option are many and its really what to you want to do with the engine and car and how deep are your pockets to pay for it.

cheers
Rohan

[S2Jay]

Speaking of various Cam profiles...[apologies for a brief thread hijack]

Tony Ingram seems to have developed his own profile that was used in a recent S2 restored car that sold on BaT [Bring-a-Trailer] for 81K USD. This was a 1706 Stroker T/C in an S2 intended, apparently, for a “fast road” type application. [<https://bringatrailer.com/listing/1965-lotus-elan-s2-12/>]
On the invoice this was noted as “ING-360-V” Profile.

Is anyone familiar with these Cams, and how they would compare in a similar application vs. other 360 or 440 Cams? [S2, 1706 Stroker, 1.625 & 1.40 Valves, port matching, mild clean-up porting, 125E Rods, CP or JE pistons, 10.5 C.R., 40 DCOE, header, 2-1/4” exhaust.]

[rgh0]

You need to talk to Tony about the specification for this cam but with the 360 designation I presume it is a copy of the original sprint cam with 0.36 inch lift. I think Tony can also supply cams similar to what I have listed below

A 0.42inch lift cam like the QED 420 or equivalent can be fitted with just spring replacement normally and in a road engine will give around 20 to 30 hp more and improved midrange torque in a 1700cc twink with 6500 rpm rev limit .

A 0.44 lift cam 285 degree seat to seat cam from John McCoy will give another 10 to 20 hp and another increase in midrange torque above that from the QED 420 but will require new longer valves in addition to springs and also probably new thin followers.

cheers
Rohan

[HCA]

If you go down the mild tuning road and take the almost mandatory QED420 cam, you may want to spend the little extra and machine the front of the shaft to take Elantrikbits 'long bolt mod'. If you do, then I suggest you contact Kent Cams and buy their D144 cam that is pretty well identical to the 420 and also well respected in the tuning world. These cams are made to order and as such, Kent will machine the longer thread during manufacture for a few pounds more... The bolts from Elantrikbits are approx £30 per set.

Does it do the job? Dunno, but I can say that two of the Cortinas I spoke with at Revival had the modification - mind you, I only spoke with two so the other four might well have had the same mod as well!

I only mention it as I am co-incidentally starting my build, helped greatly by Rohan of course ...

IMG_4169.jpeg (72.71 KiB) Viewed 874 times

[661]

You need to talk to Tony about the specification for this cam but with the 360 designation I presume it is a copy of the original sprint cam with 0.36 inch lift. I think Tony can also supply cams similar to what I have listed below

A 0.42inch lift cam like the QED 420 or equivalent can be fitted with just spring replacement normally and in a road engine will give around 20 to 30 hp more and improved midrange torque in a 1700cc twink with 6500 rpm rev limit .

A 0.44 lift cam 285 degree seat to seat cam from John McCoy will give another 10 to 20 hp and another increase in midrange torque above that from the QED 420 but will require new longer valves in addition to springs and also probably new thin followers.

cheers
Rohan

Do you think a 420 type cam would offer the same improvement in a ported Stromberg head, or are the limitations of the carbs the key area?

[rgh0]

I cant recall ever seeing a dyno result for Stromberg engine with something like a QED 420 cam in it but it should give a substantial improvement. Probably not as much as with Webers but it should be well worthwhile.

I suspect someone here has done it ?

cheers
Rohan

[seniorchristo]

I have ING-420 -V cams in my Elan. 1700 cc, 1.625 and 1.4 valves , and large exhaust.
My engine dynoed at 156 HP and I would say Tony's claim of 2000-7000 useful RPM range is accurate although I am still fine tuning things. I would suggest 1.375 exhaust valves on a .360" valve lift camshaft.

[Quart Meg Miles]

Although all the books list three Lotus cam types, the SE cam was developed progressively by Lotus engineers and gave as much power as the Sprint, even without the "Big-Valve" mods.

Miles Wilkins' personal standard Elan S3 on Strombergs turned 0-60 mph times close to 6 seconds. Its cam profile is similar to the the Sprint's which was a Tony Rudd BRM design; the rest was hype.

[Craven]

Camshaft used in the Mike Spence BRM tuned engine is a Cosworth design CPL 2 25/65/65/25 270deg Cam lift 0.360,
Sprint 26/66/66/26 272 deg Cam lift 0.360
My view is Lotus avoided a copy right problem.

[Quart Meg Miles]

Camshaft used in the Mike Spence BRM tuned engine is a Cosworth design CPL 2 25/65/65/25 270deg Cam lift 0.360,
Sprint 26/66/66/26 272 deg Cam lift 0.360
My view is Lotus avoided a copy right problem.

Tony Rudd, in his autobiography "it was fun", wrote:

"Colin Chapman asked "How would you like to build all our racing twin-cam engines?" In 1965 we [BRM] produced four versions, ..... and a 125 hp, which eventually became the 1971 Lotus Big Valve".

[Craven]

"Colin Chapman asked "How would you like to build all our racing twin-cam engines?" In 1965 we [BRM] produced four versions, ..... and a 125 hp, which eventually became the 1971 Lotus Big Valve"

As you say the rest is hype,
A Lotus Cortina shown at the London Racing Car show January 1963 fitted with Cosworth CPL 2 cam.
BRM project 125 Twincam engine.
Test results from the BRM Dyno
25/1/67 Type C cam ( Weber SE ) 121 BHP
26/1/67 Type CPL2 cam 129 BHP
30/1/67 Type L1 141 BHP