Upgrade 2.4 to 2.5? - Page 2

cnavarro · 11-12-2005, 11:22 AM

If you were to go with Nickies, you don't have to limit yourself to the 84mm or 85mm bore sizes- there really is no reason not to do at least the 85mm or preferably, the 87.5mm, since there would be no measurable difference in longevity and the added displacement would most certainly give you more low end torque. I would even suggest running 9.5:1 or doing a 9.8:1 S spec JE in any of those bore sizes with single plug. Maybe camgrinder can suggest something a little more lively, say a solex grind, to take advantage of the added displacement and compression, but something that won't throw the MFI off?

kenikh · 11-12-2005, 12:12 PM

As an example, I believe that a 2.4S that switches from 2.4S pistons to 2.2S pistons comes in around 9.9:1 and runs on single plugs on pump gas.

cnavarro · 11-12-2005, 01:56 PM

Yup, that's the ticket. You can use the same "S" profile and basically up the bore size and just adjust the piston dome height.

Fdalgas911T · 11-12-2005, 06:51 PM

So the larger displacement is more desireable... bigger = more power overall including low end torque. and the S profile is more lift, different timing and duration lift vs the E. I was under the impression the S profile produced its peak power in the upper rpms and the E was more in the midrage... lower RPM vs the S. Know where i can observe some power torque curves of E vs S profiles? Will the S profile require new valve springs vs the T. E.?

cnavarro · 11-13-2005, 05:26 AM

I was referring the the "S" spec 9.8:1 pistons, not the S cams. Sorry!

Fdalgas911T · 11-13-2005, 08:06 AM

cnararro, Were you recommending an increase in compression (over 9:1 I'm currently considering) or a piston characteristic (shape, etc) of the "S" spec 9.8:1 or something else I may not be considering?

(By the way, do you have NICKIES in your 2.2T?)

kenikh · 11-13-2005, 08:26 AM

Yes, he is and his advice is as good as it gets. You should be running between 9.8 and 10 to 1 in a 2.4.

cnavarro · 11-13-2005, 08:49 AM

It's on my schedule for next year to put on a set of 87.5s, as long as Souk can squeeze me in :-)

I've only had my T since March and I'm trying to get my '66 912 done and back on the road first, as well as my '72 vw squareback that has been sitting for years without a drivetrain since I restored it. :-)

cnavarro · 11-13-2005, 08:50 AM

And yes, in the 9.8:1! I may go to efi and dual plug it, then do something more, but we'll see how much time I have once the newborn arrives in Thanksgiving. :-)

Fdalgas911T · 11-13-2005, 01:52 PM

With 9.8:1 will an E cam run on pump gas or will the S cam profile be required? Is there a downside to the S cam. I desire a reliable long lasting street machine with some big city traffic driving. (Plus, I don't currently have an oil cooler and oil cooler setups are more difficult to find/create for the 1972 with the unique oil tank behind the passenger door.
.

kenikh · 11-13-2005, 06:04 PM

You can get a Carrera oil cooler w/ fan for the front fender well. That will solve your problems, including in the Texas heat. I drive an 'S' cammed 2.0 (9.9:1) in Seattle traffic and find it to be JUST FINE. I think when people say an 'S' has no torque, they are comparing it to a 3.2. An 'S' will still have more poop than any grocery getter.

cnavarro · 09:05 AM

That's good to know about the S cams! Although I have probably already mentioned it, some proven figures I have from our own dyno testing showed a 30F reduction in oil temps when switching from a cast iron or biral cylinder to Nickies (the results should be approximately the same for aluminum, although the thermal efficiencies of alloys differ). Torque and horsepower in every test was at least 15% more too, which we figure to lower cylinder temperatures and higher VE #s. Unless you're going to be tracking the car, I don't think you'll need an external oil cooler (it can always be added later). Just run a good syn after break in and you'll be golden. Fuel injection can help to reduce the temperature and get more power through better tuning which you could always go to at a later date.

orange911 · 02-05-2007, 11:40 AM

After reading through all these threads, I never found any results. Did the motor ever get built? I would love to transform my T in to 87.5 9.8:1 E cams and rebuild on the injection pump. Still learning though.

Fdalgas911T · 02-07-2007, 05:56 PM

Orange911:`I finally decided to build a 2.7 with new 90MM Mahle Nikasil cylinders, a modified S cam (DC40 profile), EFI, and Motec control. If you are interested, there's another thread with more info and some photos here: Advice on EFI injector to replace MFI

criv911 · 02-08-2007, 04:09 AM

I have 86.7 mahle pistons and cylinders that I would be willing to sell if anyone is interested. In fact I rebuilt my first engine to these specs buy over boring the 84mm T cylinders and having Weisco make custom pistons. I used MFI and a Elgin mod S cam ported heads. Makes one fun motor.

911pcars · 02-08-2007, 12:42 PM

Quote:

Originally posted by Fdalgas911T
Orange911:`I finally decided to build a 2.7 with new 90MM Mahle Nikasil cylinders, a modified S cam (DC40 profile), EFI, and Motec control. If you are interested, there's another thread with more info and some photos here: Advice on EFI injector to replace MFI

I was going to suggest that too, but you ended up with the same conclusion. There is no substitute for cubin inches. After passing the slippery slope of installing case savers, there's only a little difference after finding a reasonable set of 2.7 RS P/Cs. Planned EFI and Motec indicate you have a workable budget.

Best wishes,
Sherwood

orange911 · 02-09-2007, 04:04 AM

What would I have to do for my T MFI induction if I wanted to keep the MFI. By the way I ordered wayne's book from our host on Mon and should arrive today.

criv911 · 02-09-2007, 05:04 AM

You have to have the pump recalibrated, the throttle bodies have to be ported, and you need S stacks. The throttle plates in a 73 T are the same size as an S so the porting only need be from the plate down to the head. If your TB's need rebuilding anyway then you can enlarge the butterflies.

criv911 · 02-09-2007, 05:11 AM

Wayne's book is great but, if you don't have Bruce Anderson's get it. I'm sure Wayne knows far more than I ever will [MIT grad and all] but, he just doesn't cover the old stuff as well in his book. It may just be that Bruce's book was written some time ago.