-6 cams, any insight or places to do research? Options

[seanery]

It sounds like my six is going back together. It currently is:
2.7 RS pistons, webers, headers, ported heads, E cams... this is a track car. Is there a better set of cams? I don't wanna change a lot of other stuff, like rebuilding the heads (they were done when the build started a couple years ago).

Anyone have a webpage or FAQ that could help direct me?

[Joe Bob]

Guy(s) to ask.....Chris Campbell or Ottos....aka John Williams. Chris is easier to get a hold of and has a thinner crust..... (IMG:style_emoticons/default/laugh.gif)

I'm more familiar with FI cams.....the 964 profile and the 20/21. Post results as the 2.7 motor in Blondie also has E cams and webers, so I will learning along with you.

[steve@ottosvenice.com]

We have Web grind to spec .Steve

[ArtechnikA]

2.7 RS pistons, webers, headers, ported heads, E cams... this is a track car. Is there a better set of cams?

Anyone have a webpage or FAQ that could help direct me?

you have Anderson's 911 Performance Handbook, right ? good section in there on cam characterisation. give me a couple hours and i'll see if i can find cam specs from the 2,7RS - i have -the- 'Carrera RS' book and all that stuff is listed if i can't find it in '911 Story'.

several people lately have reported very good results with 'S' cams. while they're peaky in the little motors the word is they mellow out with increased displacement.

if you're using 'E' cams, you're going to be limited to 3-bearing (early) cams unless you want to upgrade to later-style 4-bearing cam boxes... all the 'new profile' GE cams, fr instance, are ground on 4-bearing billets (as are, IIRC, the 964 cams Mikey recommends ...)

as always - condition of the valve train (double springs, etc...) must be consistent with the total lift provided by the 'S' cams. and you must be -very- careful about piston-valve clearance of course ...

the '906' and 'RSR Sprint cams' have good reputations on the track - but i don't remember when the cam bearing change was made to know if the RSR Sprint cams are 3- or 4-bearing styles ...

i have 'E' cams in the 911 (it's an E!) but also in the 2,0 /6 with the original 40IDTP13C Webers - albeit with larger venturiis and some other detail tweaks... runs nice ... early 'S' cams may be the ticket for your application, tho ...

[seanery]

This is what I found at webcam:

120/104
.476/.450 284/270 264/248
Strong mid and upper end power for hot street and club racing. Carburetors or mechanical injection.
regrind your cams 05-261 $670.00
new cams 05-262 $820.00

464/465
.470/.440 280/262 256/238
Excellent profile for the 2.7 liter engines. Good torque and better acceleration. Designed for hot street and club racing. Carburetors or mechanical injection.
regind your cams 05-401 $670.00
new cams 05-402 $820.00

[Eric_Shea]

(IMG:style_emoticons/default/agree.gif) Spend the afternoon with the engine chart in Bruce's book. It's a good place the get your head around cam grinds etc. There's some newer grinds out there now so don't bury your head in the sand with it.

If you have 2.7 RS pistons then an S-cam grind might be the ticket to extract a bit more power from that engine. There were no clearance problems with those pistons and that cam. You should expect around 200hp with the S-cams and carbs. MFI looked like it was good for another 10hp. The factory was always a bit low on the hp ratings so you might see 210-220hp...??

I'm building a 930/07 (1980 3.0 SC) block as a 3.0 RS motor currently. I had Web put an S grind on a pair of 4 bearing cams with the pump drive on the left cam. This cam requires I get a new set of JE pistons to work with it. I'm sticking with 36mm intake ports to keep a broader torque curve with the S-cams. Others have gone 39mm and 40mm and they'll encourage you to do the same but, after reading through damn near every motor spec in Bruce's book, I noticed the factory never went over 36mm with the S-cams. You can gain a few more ponies on the very top end by opening up the ports like that but, on the tracks I've been on, the advantage (especially in a 914) is in the corners where you may not have the engine screaming along at 7,000rpm. The engine I'm currently building is for my 911 RS clone and it will be mainly street driven with an occasional autocross (another reason I'm sticking to 36mm intake ports). I'm building the 914-6/GT clone for racing purposes. When the factory went with larger ports they used the 906 cams... you might want to go that route.

Let the confusion begin... (IMG:style_emoticons/default/laugh.gif)

[TimT]

Web Cam 20/21 (have on my 3.2) pulls like a *^(&*

Web Cam 158R had on my 2.2 nice power good torque

Web Cam 104/102 sounds promising

The GE 60 and GE 80 are possibilities also

[retrotech]

which is more radical, the Ge60 or Ge80?

[seanery]

the 80 seems to be

[seanery]

I'm trying to make sense of all the numbers. Bruce Anderson lists Intake lift & Duration, Exhaust lift & duration & lobe center (degrees). Webcam lists valve lift (intake/exhaust) duration (degrees) & duration at .050 in degrees. how do I compare if they don't list the exact same stuff, or do they and I don't get it?

webcam doesn't specifiy if the duration is intake or exhaust and what is duration @ .050? what does lobe center mean?

Bruce's book only has a small section on cams, with no help on the different lingo that others use.

[ArtechnikA]

did a little research. 4-bearing cam boxes were used in the 2,8 RS in 1973 (as were needle roller bearings in the front A-Arms !). i'd have to infer that the 'RSR Sprint Race' cams that followed were also 4-bearing cams.

'street' Carrera 2,7RS used 8,5:1 compression and delivered 210 HP. the racing 2,8RS delivered 300 bhp. (Porsche consistently used 10,3:1 CR in racing engines...)

Jerry has been quite consistent with his camshaft designations: bigger number, more radical.

also note when comparing Porsche camshaft specs with US camshaft specs that Porsche specifies timing at 0,1mm lift (0,040"), while US typically specs at 0,050" lift. the same cam will show different timing with different measurement technique...

if anybody still needs me to drag out the big RS book, lemme know...

[steve@ottosvenice.com]

8-)

[Brad Roberts]

I love engines. Good shot Steve (IMG:style_emoticons/default/clap56.gif) We really need for you to start sharing some of the Otto's projects going on in the shop.

We are currently using the GE100's in a short stroke 3.2. It has NO power below 5k RPM and pulls thru 8200 RPM and laid down over 320hp on Woods dyno with the TECIII and 52mm TWM's.

We run GE60's in a 3.0 pump gas engine with 9.5:1 compression. It laid down 245hp with 46 IDA's and only makes power above 3k RPM and pulls nicely to 7k.

I highly recommend the Aase springs or the Woods springs.. otherwise.. you will not get the most out of these cams.

B