28 replies to this topic

[Dusky]

[carbon]

Don't understand - are these power/torque curves real engine plots?

 

If so they must be supercharged!

[Cooperman]

Those graphs don't seem to make much sense.

The best graphs are the ones in the Kent catalogue, available on-line. The SW10 torque seems to be higher at 1200 rpm than it is at 1600 rpm and peak torque is only 12% higher at 4600 rpm than it is at 1200 rpm.

[Dusky]

It are the graphs from russelengineering, supposed to be power potential, hè made a whole article about cam choice. Most people just don't get that a 266 cam wil give more bhp under (for example 4k) than a 310 cam..

[Cooperman]

It are the graphs from russelengineering, supposed to be power potential, hè made a whole article about cam choice. Most people just don't get that a 266 cam wil give more bhp under (for example 4k) than a 310 cam..

If they looked at the on-line Kent Cams site they would easily understand it.

The fault lies with the two 'comics' which bang-on about 1380 engines with the wrong cams for the application and how they are wonderful, etc.

[Fast Ivan]

building a new engine for my mini and got it stripped down and new pistons ordered to get rebored next week to a 1330. what cam do people recommend? it will be driven quite a lot but not really a daily, not wanting anything too lumpy but would like some decent power, what do people recommend? also got 1.5 titan roller rockers and getting the head port and polished. any other tips for good power gains? thanks

Have a look at AC Dodd's Rs cam.
Might also be worth forgetting the 1.5 rockers and putting the money towards the head work

Edited by Fast Ivan, 03 September 2015 - 09:46 PM.

[carbon]

Sounds like the OP has already got 1.5 titan roller rockers and also getting the head port and polished.

 

So I think it's more a question of which cam might work well for fast road. If he's planning to use the 1.5 rockers then a cam with about 250-270 inlet duration and 270-285 exhaust with 250 to 285 thou lift at the cam lobe should be in the right ball park. And that still gives quite a few cam profiles to choose from...

[Cooperman]

Sounds like the OP has already got 1.5 titan roller rockers and also getting the head port and polished.

 

So I think it's more a question of which cam might work well for fast road. If he's planning to use the 1.5 rockers then a cam with about 250-270 inlet duration and 270-285 exhaust with 250 to 285 thou lift at the cam lobe should be in the right ball park. And that still gives quite a few cam profiles to choose from...

That sounds like a Kent 266. Apparently the 1.5:1 rockers work well with a 266. They certainly don't do much with the hotter cams.

[gazza82]

That's music to my ears ... my planned set-up

[Vipernoir]

I built a 1293 for a friend last year with a 266 and an off the shelf head.

83 horsies and 83 torques on a road known to be within a percent or two of Swiftunes dyno.

[kyle9832]

It all depends on how many revs you are prepared to use to get the best power.

 

A 266 will give max power at 5700 rpm, so you'll be using around 6000 rpm when making it go at its best, so full balancing is not essential.

A 276 peaks at 6100 rpm, so use 6400 rpm as change-up revs when using max power.

A 286 peaks at 6400 rpm so use 6800 rpm when using the engine fully. This will require full balancing plus a centre main bearing strap, etc.

 

If you don't want the high revs and consequent higher engine wear then use a softer cam.

There is no point in 'over-camming' an engine and then never using full power. To keep a 286 properly 'on the cam' it needs a low FDR, like a 3.76 or lower, and a close ratio straight-cut gear set, which is not ideal for normal road use.

does this also apply for a 998? I am going to be using a 276 in my build does this mean that it will need balancing and a strap?

[Covert]

Whats the strap for then guys ?

[Fast Ivan]

Centre main strap, strenthens the centre main cap on the crank. Mainly for high revving engines. Some say that they aren't needed and some say that line boring/honing is needed after one is fitted.

[Dusky]

I'd like to add this article too about main bearings : http://www.calverst.... cap issues.htm