questions!

[911tmaster]

OK,
i have a 2.2L "T" motor and i am putting a 2.4L crank and rods so it should make it 2.4L. i already have new p and c's that are 2.2L "T" pistons and cylenders so they should give me higher compression with the 2.4L crank.

what kind of cams can i use? will s or solex cams make the valves hit the pistons?

and carbs. i want to convert to 40mm webers. anyone have any that are cheap?(maybe $500-600)

i also plan on installing oil squirters, rounding off the cross members in the case, port and polishing the heads, and i'm putting headers and a bursh muffler in it. bruce anderson says in his book i can do this but it does not say the other things i need to do. and does anyone know what horsepower and torque may end up being? and finally are these ideas to gain power good ones?

answers to any of these questions and some advice will be very helpful! thankyou.

p.s. i think i have asks a couple of these questions before but i'm confused on some of these things so i just want to organize my thoughts.

[911tmaster]

bump

[911tmaster]

bump

[pwd72s]

Chuck Stoddard, writing for PORSCHE PANORAMA, January 1972 issue; article title: THe 2.4 engine for '72
"At this point, the eager PCAer probably has thoughts about stroking his '71 crankshaft, buying some '72 rods, and this create a low cost high compression "hotrod". Assuming one tried this with a 911-E or a 911S crankshaft, the first problem is that because the crank journals are progressively depth hardened, (hardest on the wearing surface) it would be nearly impossible to accurately regrind them eccentrically, and then re-heatreat to restore proper hardness, etc. THere would also be an increase in compression ratio due to the increase of stroke. (Formula given edited out here) By applying the known values from the '71 engine ...it is easy to predict the R (compression ratio) for the hotrod which turns out to be over 10/1. THis is a bit much for longevity and highway use. HOwever, it is physically possible to install a '72 crank, rods, and pistons and cylinders in a '71 engine, but then the fuel injection pump will not to the displacement. Changes to the fuel metering system are not easily accomplished, or recommended."

So, there..in a free time warp, Chuck Stoddard's thoughts..

[Bobboloo]

I believe you have to stay with the t cams for clearance. Since your going with carbs the change in dissplacement is not an issue for MFI.(which I don't believe you have since yours is a 2.2T motor,Zeniths right?) Basically you'll end up with a higher compression 2.4T motor. The Euro 2.4T motor had carbs and was rated at 130HP@5600 w/7.5:1 comp. Yours would be around 9.1:1 so I'll make a wild guess 137HP?

Bobby

[Wayne 962]

What type of driving are you planning on doing? Where do you want your power band? You need to answer those questions before we can make recommendations...

-Wayne

[jluetjen]

Justin;
The 2.4E's (165HP) used the same ports as you've got on your T heads. Used on the 2.4E's the heads had about the highest intake gas speed of any of the early 911's that I've checked the data on (about 100 meters/second). In spite of that no one ever suggested that the 2.4Es felt chocked. Since Porsche seemed to keep the intake gas speed for the early 911's between 70 m/s and 100 m/s, I don't think that you want to get any wilder then 100 m/s. BTW; a second data point is the 2.7 with CIS also used the same port size and put out 150 HP.

$/HP, I don't think that its going to be worth the money to port your heads if your going to only use E cams or moreso the milder T cams. With E cams I suspect that you'll be in the 155-160 HP range no matter what you do with the porting. In order to get more then that you'll have to think of some way of improving the BMEP of the engine which is in the 140 psi (max HP) to 156 psi (max torque) range for all of the E motors even though the gas speed ranged from 89 m/s (2.0E) up to 100 m/s on the 2.4. Changing the BMEP involves changing the cams or significant reengineering. If you went with the E cams and Weber carbs I'm betting that you'll see about ~158 HP when it's all said and done. I'm guessing that based on the 2.4E's 165 HP -10HP for swapping the MFI with Webers and +3HP for the higher compression and other mods such as 'boat-tailing' the case. Those are just guesses on my part though.

If you decide to go with S cams, then you might want to consider porting the heads. T heads with on a 2.4 with S cams (and the S's rev range) would generate an intake gas speed of 105 m/s which seems to be too high. With the heads ported out to 34mm it would result in a speed of 93 m/s and the stock S porting of 36 mm results in a gas speed of 83 m/s. The result of that configuration should be up closer to 190 HP. I would recommend that you evaluate the other components of the motor to determine if they'll survive the 7200 RPM's required to generate that sort of HP. No matter what cam you use (E, S or even T), you should be sure to check the valve clearences so that they don't have a "spatial event" with the pistons.

BTW: You can often find webers in that price range on EBay, often with rain shield, linkages etc. Just keep in mind: Buyer beware and check the sellers previous feedback closely.