Modify a 2,2

[jasam]

Hi everyone I have a simple question... I'm going to modify a little bit my 911 (70 2.2 T) and I want some suggestions:


I don't want to do any swaps or anything alike I just want to gain some power and I think of two possibilities:


1--> 86 mm 10:5.1 pistons and 2.4/2.7 crank, Fidanza flywheel plus some work with the heads

2--> 84 mm 10:5.1 pistons fidanza flywheel and the work in the heads

I have that two options but I'm open to changes of a different way to gain power but as far as I've seen it's the most common way to modify an early 911 with 2.2 engine.

Plus I'm changing the Torsion bars and the anti-sway bars for a Tarret and ER.

Have you tried the Rennshift for a 901?

Hope you could advice me about it

[jasam]

nobody ?

[304065]

Welcome to the forum. You will find that many, many others have had the same question before. Using the search feature turns up threads like the following:

2.2T with 40IDTP3C1 webers to be converted
Rebuilding 2.2T to a 2.2 race motor...Thoughts?
Upgrade 2.4 to 2.5?

There are more threads in the archives. But to give you a specific answer, the 911T is a difficult starting point for a high-performance engine because virtually everything will need to be changed. For example, the case is magnesium and will probably require a line bore and perhaps other machine work like fixing the through-bolt holes or machining the spigots flat. Also, depending on whether your case has squirters, you may want those to be installed, and the oil bypass modification is definitely recommended anytime the case is apart.

The 1970 911T crank was not counterweighted. Some racers prefer this crank because of the lower rotational mass, but it is noisier and the bearings will wear faster than a counterweighted version.

The cast-iron cylinders are not the best choice for a high-performance application. Even 84mm Birals should probably only be bored to 85, so if you are looking for 86, you should consider an aftermarket cylinder.

10.5:1 will require twin plugging the heads with the associated distributor modification, or crank-fire direct ignition.

External oil cooling will definitely be required, so factor that into your plans. Pelican sells the required parts and Elephant Racing has an excellent web site as well.

Finally, the carburetors will need to be modified to cope with increased power, which is difficult to do with Zeniths.

Zenith 40 TIN Carbs

I hope this is helpful to you.

[Grady Clay]

jasam,
I’ll second the welcome.
You will find a lot of help here.

I’ll offer another suggestion – build yourself a separate hot-rod engine and preserve your virgin 2.2T.

I’ll start with the outrageous. Buy a good 2.4/2.7 core with a 7R case. Build a 2.8S, twin-plug, MFI at 11.5:1 and use race gas. A 2.7RS with the CR carefully bumped (still twin-plug) is a good option. PMOs in place of MFI or EFI reduce the monetary cost – at a performance cost.

While there is the good economic option of a 3.0 or 3.2, there is a weight penalty and transmission issue with larger torque and hp.

Best,
Grady

[jasam]

Hi guys, thanks so much for your advice. As I read the posts I see that is not such a good idea to stroke my 911, but I don't like the idea of swapping the engine, I'd like the originality of a car but I just want some extra power.

I read the options of changing the cams and the pistons and the crank (thx john for the links) , I'd like to keep my car as good as possible considering that is not a track car, it's a weekend car, that may go once or twice a year to a track day.

That being said what do you recommend, the cams? or the 2.4 crank? or the pistons with a higher CR?.

My mechanic told me that I shouldn't change the crank nor the cams, he told me to change the pistons for the higher CR and polishing the heads combined with the flywheel and that will make a nice car to drive...

What would you change ? some parts to E specs maybe S or 2.4?


I'd like to reach the S bhp specs more less

[Grady Clay]

jasam,

OK, lets analyze the pro & con of three common “improvements” for a 2.2T: The longer stroke crank, larger bore P&Cs (with whatever CR) and cams/induction.

The OE crank is a non-counterweight 66 mm stroke cast steel part. The replacement is a 70.4 mm stroke counterweighted forged steel part common to 2.4 & 2.7 engines. The connecting rods are necessarily different and must be changed with the crank. The crankcase must also be relieved for piston clearance at BDC.

The longer stroke increases the displacement in direct proportion to the change in stroke. Conventional wisdom says the increase in stroke has slightly greater increase in torque compared to hp.


Without changing the case spigot bore (92 mm), about the largest piston is 86 mm using custom (modified) cylinders and new pistons. Your stock 2.2 pistons are 84 mm diameter. The larger bore increases the displacement in square proportion to the bore. Conventional wisdom says the increase in bore has slightly greater increase in hp compared to torque.

It is common for the case to be modified to accept the larger (97 mm) cylinders spigots. The bore can be increased to 93 mm max. Normally the conversion is to the 90 mm 911 Carrera RS (8.5:1) or the 92 mm 911RSR (11.3:1) Mahle Nikasil. There are also aftermarket (JE) pistons available.


The performance of the heads, cams, intake and exhaust can collectively be called “breathing.” All of these issues must be addressed in concert. Simply changing cams without addressing port size and carburetor venturi (and jetting) doesn’t work well. A 2.2T already has great headers (heat exchangers).

As an aside, twin ignition improves performance (and drivability) and slightly reduces octane requirements.


OK, that is the quick tour. There are other important issues.

Probably most significant is the crankcase. You should look at the casting numbers on both sides of the case halves. I suspect they are 901.101.101.3R and 901.101.102.3R. The crankcase strength increased over the years with the 7R being the final (and strongest) version.

The OE Zeniths do not have performance (or even adjustment) spare parts available but you can make your own. Appropriate replacements are Webers and even better PMOs.


If you start with a ’72-’73 2.4 911T MFI core engine you have the basics for a 2.8S. The greatest benefit is you can take your time building the engine while maintaining your 911 in service. You can also build another engine where it appears exactly (911E or 911S) period correct.


I recommend you study two important books:
Anderson, B.; Porsche 911 Performance Handbook
Dempsey, W.; How To Rebuild & Modify Porsche 911 Engines
These are available from out host.

While you study both of these books, write yourself a proposed plan. You can then discuss that with knowledgeable engine builders and post it here for discussion. By doing this you can turn a vague engine idea into an action plan, complete with all the technology, contract services and cost estimates. The best part is at this point you only have some time and the book cost invested.

Best,
Grady

[jasam]

Hi Grady, thanks for the information, I ordered the Anderson, B.; Porsche 911 Performance Handbook, hope it gets here in a couple of days.

I'll build an exact plan for the car and then I'll post it, but I think it would be my mechanic's plan moving foward so far, but I'm not going to decide until I read the book....

If you were in my position and you would like to keep the engine with no extravaganza modifications, what would you do?

I'll think I'll focus now in the 'Breathing' side changing pistons to S spec with E or S cams and will change the venturis of the Zeniths, this carbs can be pretty good (not as PMO) and would work nice... I'd like to reach the S specs... I don't like to give my engine a 30 hour life.

Thanks for you incredible help.

John

[304065]

John,

If you want the car to be faster around the race track, spend your money on the suspension modifications. The shifter works fine, I have a few podium finishes in class with the stock shifter. A 2,2T is plenty powerful, you just have to keep your foot flat longer.

[jasam]

Originally posted by john_cramer
John,

If you want the car to be faster around the race track, spend your money on the suspension modifications. The shifter works fine, I have a few podium finishes in class with the stock shifter. A 2,2T is plenty powerful, you just have to keep your foot flat longer.

hehe I'll keep that in mind (In fact is the first mod I did, torsion bars and brake lines, and I'll get anti sways soon from tarret plus bushings bought in ER).

Do you race with you 911 E? if you do, is it stock?

[Grady Clay]

John jasam,

Perhaps we should back up a little bit. What is your intended use? There are many choices and combinations. Some require specific solutions, others are a collection of engineering compromises. You will find many very experienced experts here.

First you need to look at the overall condition of your 911. Is there rust? Is there prior crash damage and repair? What is the long-term maintenance condition? Good that you installed stiffer torsion bars. What is the condition of the rest of the suspension? What tires & wheels?

You need to step back and analyze if your 911 is appropriate for your goals and situation. Some are not.


Depending on your intended use (and budget), these are important issues. There are a tri-polar description of your quest. The three axis are: street, race and “café racing” (appearance). Your mission is to decide which axis you want to go toward. Everything you do is a compromise. The key is to understand the pro & con of every decision and make the compromises appropriate for what you want.

This forum can help you not make a mistake. Only you can direct the compromises.

Best,
Grady

[jasam]

Originally posted by Grady Clay
John jasam,

First you need to look at the overall condition of your 911.

You need to step back and analyze if your 911 is appropriate for your goals and situation. Some are not.


“cafeé racing” (appearance).

My car has never been in a crash or something, it has 52500 original miles with original paint, and of course original interior... to end it fast... it is completely original

Sorry for my ignorance, a "café racing"... what it is exactly? I found that, but mostly used as a bike term... It is when you modify your car in appearance and a little bit mechanically ? or what does it mean this....

To end fast I love my car being narrow body even though I would love to have an RS but I don't like to cut the cars so much so I rather enjoy my little car as a Narrow body, but as I insist I'd like to have 30-50 bhp more hahaha no to have a 2.8 RSR

A must in my car is the S spoiler .... I love that look haha, the only looking mod that is scheduled.

And let me say again thank you so much for being so helpful with me...


P.S. you can call me John hehe, JASAM are actually my initials John Albert Salinas M.

[Grady Clay]

John jasam,

Great, we are on the same page.

Now comes careful consideration of what you want and how the Pelican Forum can help. If you are not DIY, there are many shops that can help, advise and perform what you want. Henry is one. There are many others.

I did this from the late ‘60s to the mid ‘80s and retired. Many (ANDIAL, Garretson and others) were patterned after what I did. We all cooperated with information. That same cooperation is now on Pelican for everyone’s benefit.

Best,
Grady

[jasam]

Hi, I'm beginning with the plan, but I need the specs of my stock cams, do you guys know what are the specs of my 2.2 T cams?

[jasam]

Originally posted by Grady Clay
jasam,

OK, that is the quick tour. There are other important issues.

Probably most significant is the crankcase. You should look at the casting numbers on both sides of the case halves. I suspect they are 901.101.101.3R and 901.101.102.3R. The crankcase strength increased over the years with the 7R being the final (and strongest) version.

Best,
Grady

Fan shroud number is 901.106.101.5R
6106042 from a 911 T
911/07 don't know what it is

[JCF]

911/07 - That's the engine type # for the 70-71 2.2 T (USA)

[jasam]

Originally posted by JCF
911/07 - That's the engine type # for the 70-71 2.2 T (USA)

Thank you for the information.


I can't wait for the books to arrive, plus I'm making already a plan for my 2.2, I'll post it as soon as we finish it.


P.S. thx everyone that helped with my questions, and John C. hope you received the PM