2.2 T -> 2.4 upgrade suggestions ?

[blackbird225]

A buddy from this list ( BK911 ) has suggested that I stroke my puny 2.2T using a 2.4/2.7 std/std crank. In Waynes engine book, he also recomends this. I have two questions:
1)What should I pay for an already balanced / magnafluxed / polished assembled 2.4/2.7 crank?
2) Waynes book says I should use E pistons. Can I get by using my 2000 mile new T pistons, or is the E a MUST have for this setup?

Thanks in advance.

Michael

[Grady Clay]

Michael,

The first questions are:
What do you want to do with the 911?
How do you want it to be when finished?
What is your budget?

Yes you can put 2.4 crank and rods in your 2.2 case. You can also add 90 mm P&Cs for 2.7 or 92 mm for 2.8. You can use T, E, or S cams and P&Cs. You can modify the heads. And more, and more, and more.

You can see why the first three questions are so important to ask yourself and devise a plan that works for you. A very slippery slope otherwise.


Even if reusing your T P&Cs, with the longer stroke crank you should verify good clearance between the piston skirt and the crankcase & crankshaft. Your 2.2 cylinder spigots should be checked also. There is good info in Bruce Anderson’s 2nd Ed. p136, available from our host.

Best,
Grady

[blackbird225]

Well, Here's the story and direction in as short of a nutshell as I can get it.
I bought the 911 that everyone in every book hopes they never get. I am that sad story. THe guy who sold it to me is not form this list, mistake 1. HE said it was totally rebuilt, etc etc. He sent me 100's of pictures. All disguised the bad front end damage, and none could show the serious oil starvation / dirty oil damage to the cam towers. Well, someone DID rebuild it, because I have zero oil consumption and 151-152 psi in every cylinder, with 4% leakdown averages. The paint was new, there is no rust, as described, but the pan would need to be dropped, and the whole front suspension pan needs replacing. A good project for someone with those shop resources.
This weekend BK911 came over and we pulled the cam with the most known damage out. The bearing were the engine was starved is fried, gouged and scored etc. So Brian says. IF its bad here and the oil was dirty enough here, what's it like inside? Then he mentions that since you have new p/c's why not put a 2.4 crank in there to upgrade the engine. HE and I both have a case of "while your in there"-itis. If I take the cam tower off, might as well take the heads off to look at the combustion chamber. IF you go that far, might as well upgrade the puny T.
I bought a good rust free roller, and I have my engine on the floor. There is a crank for $500 that is ready to drop in. I was going to spend that on an oil fed tensioner kit, but I found that I have solid tensioners, so no need. Instant extra $500 to spend. I am pretty sure that the heads are good. I am pretty sure the p/c's are 2000 miles old, and I already have new/rec. cams and rockers. From what he was saying, I would need a gasket kit, a crank, and maybe some new bearings.
I guess my budget is about $1000-$1500 MAX incl the $500 std/std crank.

What do you think?

Michael

[Grady Clay]

Michael,

Hmmm, you have a predicament.

Considering what might be inside the engine, I wouldn’t light into it with that budget.
Ask around for a suitable fresh engine and exchange – with guarantee.

If I were in your shoes I would consider the choices:
Reassemble and sell it as “not running – needs work” but looking nice.
Disassemble it and sell the salvage.
Park it until I won the lottery.
Pour more money into it.

Probably in that order although I haven’t seen the 911. Propose this to BK911 and more local Pelicans. Get opinions from knowledgeable people who can see the 911 first hand because I may be all wet.

That said; it won’t cost any money to continue dissembling and inspecting. If you sell the car or exchange the engine, every good part you find is a bonus. The buyer will usually assume that everything is junk. You also gain much better understanding of exactly what you have in order to make a good decision. I would disassemble it completely and carefully. Clean and measure everything as if you were going to reassemble it.

Just so there can’t be a misunderstanding. You can’t just “…put a 2.4 crank in there….” It requires 2.4 – 2.7 connecting rods also.




BTW, did you consult on the screen play for the film “The Money Pit”?
Sorry, black humor.

My sincere best wishes,
Grady

[blackbird225]

BK911 looked at it and agreed that the one area was oil starved, but the rest of the cam and tower looked right. I should have mentioned that the crank comes with 2.7 rods, new bearings, polished, balanced etc. It would bolt up and be ready to go as is. I guess I will do like you said and continue the dissasembly and mic everything. My hope is that All I will need is a gasket kit and little to no machine work. ANother option is to just put the E cam in and drive it till it explodes. Others have suggested this as the new cams and rockers were the only worn part of the engine. What do you think?

michael

[Jay Auskin]

You likely won't have the proper clearances with an E cam and T pistons. Look in the rebuilding forum there's a thread on this one right now. I rebuilt my 2.4L T motor using 2.2L T pisotns. There were no clearance issues with it. So this would be basically the same engine you're looking to build. Although, I am blessed with having MFI

[blackbird225]

on that issue... camgrinder from this list reports that the E cam has a mere .08 mm life greater than the T cam. Not even 1/10th of a mm! I think the S cam would cause trouble. But I might have to trade my new T p's for some used E's if that really becomes an issue....

Michael

[Bobboloo]

$500 seems like a good price considering that you get a polished crank reconditioned rods, and new bearings.

Before you put more money into this motor though you need to access the total condition. So you would need to tear it apart and answer some questions.

The numbers sound good on the motor though so I wouldn't hesitate to run it as is but only if the oil pressure looks good.

It seems to me you might do better to concentrate on having a good chassis to run in. You could use your drivetrain as is at the moment and once the chassis is sorted then address the motor situation.

Is the chassis so bad that it's not worth fixing? Most early chassis have issues considering their age if they haven't been already addressed.

[blackbird225]

Bobboloo, I have a second, straight chassis from scca_ita off of this list. Its a nice rust free roller , T trim. In another thread someone gave me some bad news about my T pistons. I will probably need to get my hands on some E pistons. =( Either that or have the valve pockets machined down 1.5 mm. The 70 chassis is not too bad to recover, just more than I can do in my limited shop. There is no rust, and all the sheet metal is mint. the glass is mint too.

Are you suggesting running it or tearing it down?
Michael

[Grady Clay]

Guys,

It isn’t just the total lift that is an issue with valve-to-piston clearance but the timing of everything. The piston coming up chases the valve closed. The valve opening chases the piston down. There are a lot of things going on here; cam profile, cam timing, rod length-to-stroke ratio, and more.

Another issue is the valve cut-out of the piston. With race pistons and cams the relief in the piston is the same size as the valve. If the valve contacts the piston, it is usually a square contact where the piston just “helps” the valve close if it has floated from high revs. A “T” piston (and others) can only contact a valve on part of its periphery. This results in bending the valve.

Consequently, an engine with RSR pistons is less susceptible to bending valves from an over-rev than an engine with T or CIS pistons, even with much higher CR.

It is easy to build Porsche engines with all original parts. When using the mix-and-match approach, the art is to properly match everything in the mix.

Best,
Grady

[blackbird225]

Grady, Wayne wrote me back and sad the same things you are saying. He did mention that I could probably machine my T pistons with larger pockets. Worst cae scenario, I buy E pistons. We KNOW they will work with the 2.2-2.4 upgrade scenario. No biggie. I am sure someone can scrounge a set of E pistons and I am sure I can sell my 2000 mile-old T pistons. Not a big deal. Here is what Wayne suggests

Hi there. Assemble the motor dry like indicated in the book, and then measure the piston to valve clearance. Every motor is different, and I can't speak for his cams. The total lift is not what causes the major problem, but when that lift occurs (if you look at the diagram for piston clearance in the book, this becomes obvious).

If the clearances aren't big enough, then tear it down and machine pockets in the T cylinders. I believe there's enough meat on the pistons to do this...

-Wayne

I think I will do it. Everyone here said to take it down so you KNOW what is going on down there. I am getting geared up to start it this week.

Michael

[vntgspd]

If you end up blowing your budget (most of us do) and buying new pistons, I would go with the 2.2S pistons to mate with the 2.7 crank you are looking at. This will give you a higher compression ratio. Pair that with the E cams you mentioned and you will have a really sweet combination that works great on the street and track.

Then again, maybe I'm biased.

[blackbird225]

what are 2.2 S pistons gonna run me .... gulp???

[vntgspd]

Assuming you have new cylinders, you should be able to get away with buying pistons only. Check with JE Pistons in Huntington Beach, CA. They make great quality parts. I have not purchased my 911 pistons from them but I have bought a few sets of custom pistons in the past and never paid more than $125 each including rings. I suspect the higher volume on 911 pistons might make them cheaper.

As others have mentioned, any swapping of any parts within the engine may require some machine shop work to ensure that everything is within spec. So, I would budget for that too unless you are planning to build the world's most beautiful grenade.

[dtw]

It only cost me 100 bucks to have my 2.2T pistons machined - a drop in the bucket on a $5k rebuild. That mated with some hot cams and my engine is a screamer (for a 2.4).

That crank sounds like a great deal - I'd pick it up - but why not hold off making more decisions until the engine is torn down and you know just how much lunch you need to pack?

[blackbird225]

I will do JUST that. I thought I would pick up the crank because I KNOW that I want more hp out of my little T. I could get it sideways, after stomping it in a u turn with wheel fully over. I just want to get some fun out of the two years of sweat labor. The 2.4 upgrade seems like a nice upgrade. Wayne likes it, so does everybody else. Plus I hear 175hp if done right even with carbs. MFI would be nice, but I Zeniths with rebushed throttle shafts. I know I need to ream them out. Or will I HAVE to get Webers to do this upgrade?

Michael

[BK911]

If I didn’t see it, I would have never believed it. I will never use an impact wrench on a cam nut again. The wrench turned the cam nut, but the friction of the cam nut on the cam gear caused the gear to turn too. But “that other thingy”, the one keyed to the cam, did not turn. So the cam nut turned the cam gear, which spun the pin, which broke off 6 teeth on “that other thingy.” Unbelievable. I think somebody used an impact wrench when they tightened the cam nut. So lesson #1, do not use an impact wrench to tighten.

That brings us to lesson #2. A couple of rockers were toast, the cam was chewed a little, definitely discolored, and the cam box was chewed inside too. But the cam boxes were pretty clean. Actually, they were too clean. I think somebody blasted them and didn’t/couldn’t get all the media out of the oil passages. Parts of the cam were definitely running dry. So either don’t blast internal engine components, or make sure they are CLEAN!! I would be very concerned with media bits elsewhere in the engine. Not to mention the other 3 teeth we couldn’t find!

[Bobboloo]

Are you suggesting running it or tearing it down?

I know my post may have sounded contradictary. What I was trying to say is that if the oil pressure looked fine I would leave the motor alone for now and put it in the new chassis and make sure everything else like brakes, suspension, steering and alignment were good. Then address the motor. (This was before Brians most recent post however. Talk of media bits sounds scary.)

I also was saying that before I spent any money for upgrades on the motor I would tear it down completely to access its' total condition.

As for the upgrading with the T pistons you have. They presently give you a CR of 8.6:1 with your present crank. With the longer stroke your CR will go up to about 9.1:1. Not bad at all. Actually quite nice in that if you went with something like 2.2 S pistons you might have a problem finding gas with high enough octane consistantly.

2.2E pistons should give you a CR in the neighborhood of 9.6:1 which should run fine on any of the premium gas out there.

If I was going to change pistons for just a little more compression like with 2.2E pistonsthough I think I would rather spend that money on a set of bigger bore P+C's like some 90mm ones but this is the point where you enter that slippery slope. (says the guy building a twin plug 2.8 RS MFI motor$$$)

The 2.4 T motor, I just rebuilt with it's lowly 7.5:1 CR isn't a bad motor at all so I wouldn't hesitate to keep the T pistons you have. It should make a great 2.4 motor IMHO.