Best cams and heads for 2.4 hot street engine ?

RS-GT · 06-29-2010, 06:24 PM

Hi,

I was planning to use a set of early S cams I have, but they will finally need rebuilt, so having money to spend, I want to make sure I got the best for the bucks !

So far the parts on my shelve are : Stock 2.4 case, A nice Rennwerks twin plug distributor, 85mm JE pistons 10.3:1 with modified cylinders, PMO 40, MSD, SSI and custom 2 out sport muffler.

So for the cams : what are the best one to get good street driveability and good torque range ? Stock early S, Modified S by Elgin, DC40 or DC60 or others ?

By the way, for the heads, I was planning 2.4T heads, twin plugged with S ports ; should I go with bigger ports ?

Thanks for your always appreciate help !

JD

6771911esses · 06-29-2010, 06:50 PM

I love the 2.4E cams, don't know how the DC 40 or 60s compare. The E cams have mucho torque. My 2.4E has 2.2E pistons and pulls like a freight train in a SWB car. Quicker than a 3.2 Carrera!

Flieger · Flieger's Garage

S cams have it all up top- 6500-7000 rpm. 906 and RSR cams are even higher- 8000rpm plus.

I think you would like the E cams.

merbesfield · merbesfield's Garage

How hard is it to find E cams? I have a line on a 69 2.0L E block. It needs P& Cyl, cams, heads and sheet metal. Is it worth considering? Whats it worth?

Per the seller: The motor is a 69 2.0L E motor, has the e /s counterweighted crank, Short block is rebuilt stock std /std crank, new bearings (rods & mains), new cam chains has countershaft in it as well as oil pump, rebuilt rods. sized on both ends and new wrist pin bushings. The case is a desireable maagnesium case.
I have most of the hard parts, no P& Cyl, cams, heads or sheetmetal. Has cam boxes, cam chain boxes, oilcooler, thermostat as well as most all of the motor other than what i listed.

Steve@Rennsport · 07:51 PM

Quote:

Originally Posted by RS-GT

Hi,

I was planning to use a set of early S cams I have, but they will finally need rebuilt, so having money to spend, I want to make sure I got the best for the bucks !

So far the parts on my shelve are : Stock 2.4 case, A nice Rennwerks twin plug distributor, 85mm JE pistons 10.3:1 with modified cylinders, PMO 40, MSD, SSI and custom 2 out sport muffler.

So for the cams : what are the best one to get good street driveability and good torque range ? Stock early S, Modified S by Elgin, DC40 or DC60 or others ?

By the way, for the heads, I was planning 2.4T heads, twin plugged with S ports ; should I go with bigger ports ?

Thanks for your always appreciate help !

JD

This is a tough question to answer without further information such as what the car will be used for, how much it weighs, and whether you will have close-ratio gears,....

A hot-cammed ("S" or more) 2.4 has a relatively narrow powerband and needs the appropriate gearing for optimal acceleration. I'd use Solex, "E", or a custom grind if stock gears will be retained.

As a side note, I would not use that '69 engine case as a foundation for a hot-rod motor. Its the worst of the magnesium cases and frankly, only good when originality in a restoration is a high priority. I'd use a 4R/5R, 7R, or an early aluminum case for a solid, reliable engine that can turn 7K RPM without any long-term grief.

tobluforu · tobluforu's Garage

Street=E or solex for best all around fun.

bkreigsr · 08:36 AM

I'm currently running the 'mod s' with my mfi.
Very strong response from 2800 all the way up (7200).
Prior to these I ran 906 grind from WebCam where there was a huge surge at 4900, but much stronger then the regular "S" grind in the lower ranges. I should also mention that I had to get the pump profiled(cammed) for each pair of cams.
I stayed with single plug, and am running 86mm (2.5L) 908 Mahle p&c @10.37:1cr and no problems - as long as I can find 92+ octane
After you have driven a while with "E" cams, you will probably be kicking yourself for not going more aggressive - my.02
Bill K

911st · 06-30-2010, 06:03 AM

Just a thought. A 2.8 twin plug with Mod S cams is a wonderful motor that seems to be more than the some of its parts. Makes about 250hp. You could sell your P&C's. Even if you build it as a 2.7 w J&E's it would be great.

Your twin plug 2.4E will be about 200hp on a good day.

With 10/1 CR you probably want an aggressive cam and the Mod S might work for your 2.4 to. The twin plugs and extra compression will help the bottom end.

A 2.4S w high compression and twin plugs seems a good fit for a 914-6 but the 2.8 will make it rock. I had a 2.8 in my gutted 72 911 with smaller diameter 225/50 R1 tires, lsd, and it was faster to freeway speeds than a 993TT.

Having said all that I would call the 'cam grinder' and tell him what your car is and how you wish to use it.

moneymanager · 06-30-2010, 07:13 AM

I'd avoid the straight S grind in 2010... there has been a little bit of progress in the forty years since those were designed. I have the Elgin modified S cams and I love them, but the car is mostly used on the track. For just driving around, I'd do something closer to the E cam... pulls much more strongly at lower revs, much easier to live with in town.

RS-GT · 06-30-2010, 09:00 AM

Thanks for your input ! More details : the car is a 1970 S coupe, stock body. I got it as stripped tub. Not having the right 2.2S, I want something that will be agressive, but street driveable. I also think that the E cams are nice for street, but I put thousands for nice upgrade that I would really like to get the benefit of. (Twin plug, PMO and for the body : Polybronze bushings, monoballs, 21/26 T-bars, 19/19 sway bars, Alum. beam and t-arms.) The case is a 2.4T - 5R

I bought the 85 P/C' a while ago, for a good price, when thinking of keeping the costs lower, but being at this point I should maybe resale them and go with 2.7 or 2.8 ? With the same set-up what do you think is the HP difference, just between 2.4 and 2.7?

I agree that 906 or RSR are too much, I thinking toward Mod S or DC40/60 ?

Thanks !

JD

RSTarga · 06-30-2010, 09:53 AM

The big difference you will feel between a 2.4 and a 2.7 or 2.8 is the torque. Definitely worth it, if you are doing a complete rebuild this is an easy decision.

RWebb · RWebb's Garage

use a 7R

911st · 06-30-2010, 10:10 AM

About 10% more power going from a 2.4 to 2.7. Thus about 20+ HP.

I think a 2.4S it 190 and a 2.7RS is 210HP stock.

moneymanager · 06-30-2010, 10:21 AM

"Getting the benefit" of all those changes with the Mod S cam means little torque or power till 4500 rpm when it kicks in. You'll go nicely then but earlier the more conservative cam will have the edge.
2.7/2.4 = 1.125. Going to 2.7 is a no-brainer...you get a lot for not many incremental dollars. but I'd sure use a 7R case if I could.

73 911E · 73 911E's Garage

Hey guys, brand new to the site so bear with me. All this talk about cams, I just got my 73 911e last fall (first Porsche) and I'm just starting to feel comfortable pushing the speedo where it wants to be. I'm shifting at 5000 - 5800 between 3, 4 & 5th gears. I drive a mini van all day so I'm having a hard time convincing myself that these motors like the high revs. I'm assuming I should have no problem going higher if need be. I just don't want to kill it before I enjoy it.
The motor was rebuilt 6000 Km ago so it's good to go. And yes mine seems to pull like a freight train too.... love it.

tobluforu · tobluforu's Garage

Quote:

Originally Posted by 73 911E

Hey guys, brand new to the site so bear with me. All this talk about cams, I just got my 73 911e last fall (first Porsche) and I'm just starting to feel comfortable pushing the speedo where it wants to be. I'm shifting at 5000 - 5800 between 3, 4 & 5th gears. I drive a mini van all day so I'm having a hard time convincing myself that these motors like the high revs. I'm assuming I should have no problem going higher if need be. I just don't want to kill it before I enjoy it.
The motor was rebuilt 6000 Km ago so it's good to go. And yes mine seems to pull like a freight train too.... love it.

Rev the piss out of it I say! Does the car have a rotor with the rev limiter, if so then you are good to go.

911st · 06-30-2010, 03:16 PM

A 2.7/8 with E cams, high compression, and twin plugs would be a great AutoX motor and work well very with stock gear ratios.

A 7R case would be nice but if the revs are going to stay under 7200rpm it is not an absolute requirement. Not sure but I think it might have been Walt at Competition Engineering or someone of the same elk that told me such.

The mag case in and of its self is the bigger issue. If they are kept cool and built right they can last a long time. If not they can be a problem. Also note that to square up a mag case right and do all the little things it can get expensive.
Especially if one has to use oversize bearings. Better yet, sell off all the 2.4 stuff and buy a good used SC long block as a starting point. Much better foundation, comes with great TQ cams, and for what you will spend on the mag case you can easly pay for twin pluging the head.

So many ways to go.

kenikh · 06-30-2010, 03:37 PM

Words of experience: E cams are nice, Solex cams are nicer, DC-30 cams are the best street cam by far as a compromise between top end and torque on a 2.4 with S ports. You'll stomp the Es and Esses with this combo. Mod-S/DC40s are wicked, too, but slightly peaker, so judge based on your taste for character.

I tend to like peakier power, though, so given a choice, I'd build a 2.4 with Steve Weiner's small bore, big port heads, DC44s on 102 lobe center and have a ball. This is the most aggressive truly streetable motor you could build. E-like torque and 906 HP...what's not to like other than needing racing springs?