2.2t rebuild questions
 

Ok - about to start the teardown on my 2.2t. Looking for feedback on my choices.

Own the bible have read (most of) it! (Before somebody asks)

I am aiming at a a nice touring/ street engine with good mid range - not going to spend much time over 7000rpm.so not focused on top end power. Guess hoping to get to something like 150hp

Am going to do a total rebuild so:

- add piston squirters
- Oil bypass mod
- Case savers

I am inclined towards a short stroke and reuse whatever I can so thinking
- keep t crank
- refresh t heads
- double springs
- bore out my iron cylinders to 86mm (have read some saying I can't and some saying no problem)
- - je pistons (9.5:1)
- e cams (or DC30? is this worth it given I am sticking with t crank so wont be high rev motor)
- Weber 40s

- was hoping to avoid adding an oil cooler - interested if you think possible with this aetup

Thoughts?

Thanks in advance

Here are few thoughts highlighted in red.
Cheers

Henry wrote: “The aluminum fins will help pull the heat created by additional hp form the head. Laws of thermal dynamic tell us the heat travels from iron to aluminum not vise versa.”

That is flat wrong. The engineering field of heat transfer has established that heat always moves from higher temperature materials to lower temperature (in thermodynamic lexicon, from a higher temperature reservoir to a lower temperature reservoir). Material type does NOT affect the direction of heat transfer, only the rate.

The reason for aluminum fins on Biral cylinders is to conduct heat more quickly away from the hotter cylinders to the air flow, because aluminum has a higher K value than iron—i.e., it is more conductive. That provides a higher rate of heat transfer.

Always looking to one up the experts. It's cute AF.
The statement I made was inarticulate but correct. I should have said "cylinders" not just materials. The iron cylinder will always retain more heat than the aluminum cylinder and as soon as the iron cylinders lose their (air) cooling as in cool down mode, the heat from the cast iron cylinder will transfer to the heads. Not so with the aluminum cylinders. Heat travels from hot to cold and aluminum cylinder in the same environment as cast iron will always cool the heads better.

Thanks for your feedback Henry - I have a lot to learn, and your comments have raised more questions for me.

The bible I jokingly referred to is Wayne Dempsey's book.

I did read on this forum of somebody who successfully bored out to 86mm with no problems but I have also read a lot of folks like you who say not to, so I'll take that as a warning. Sounds like you recommend the biral anyway as they will cool better so might just bite the bullet and replace.

Out of interest - why don't iron cylinders need the squirters? I appreciate they didn't have them originally but wouldn't it be a good idea to have them if I am splitting the case anyway to help cool the pistons?

The Je pistons I was looking at are 9.2:1 with my crank and are actually advertised as low compression which is a bit weird given your comment that 9:1 would be a better target. I live in UK and 98/9 octane is readily available here.


Is the SC pump something you think necessary? Appreciate everything helps, but I am working to a budget and wonder whether the original pump will suffice if its in good condition.

So here are my take aways:

- Go with new birals over original iron cyls
- Add a front oil cooler

Thanks again for your help

If you're on budget and hoping to go with JE pistons and Biral barrels you should check out AA Performance Products. The cylinders are Chinese but reasonable quality and they offer a JE piston option. I've sold a few sets over the years and except for some ring gap issues with the 86mm, no complaints.

Thanks for this info. I have been looking at the aa package you mention. Given I was hoping to go for 86mm your comment is a bit worrying!! - how did you remedy the excessive ring gap? Did the replace the rings?

We've seen the same issue with the AA 86mm Biral cylinders.
What we've done in the past was to have the cylinder Nikasil coated. This does three things. It allows us to control the bore size, RA factor and the Nikasil reduces friction so the cylinder runs cooler. Nikasil may also reduce heat transfer keeping the energy in the cylinder but that is simply speculation. I have no data to prove that.
Of course this requires an attention to detail beyond, plug and play. The ring pact is different (Nikasil vs cast iron) and piston clearance can be slightly tighter to reduce piston noise. We've had pretty good luck using Wossner pistons in conjunction with Biral barrels. Very quiet running. They make a shelf 85mm that is easy to source. 85mm is a safe bore size for cast iron and Biral 84mm. The benefit to coating the stock cylinder is that you can reuse 84mm pistons if they are still in spec and by reusing the older style Biral cylinders you can maintain the concours aesthetics.
As for boring the cast 84 to 86mm: you can do it but it gets very thin. We've seen at least 2 different attempts at this modification result in cracked cylinder just above the spigot. Sometime "it woks" is simply a reflection of attention to detail or lack there of.

I was in your shoes on my 2.2T rebuild and here's what I did:

- all the case machine work including squirters
- four-rib SC oil pump
- stock crank and rods
- Mahle 9.8:1 S p/c's
- mod-Solex cams

I have zero heat issues -- in fact, the engine runs a little cool in street driving. I've tested the thermostat and used an IR temp gun and it just runs cool, unless it's warm out and you get on it for a while.

Only thing I would do different is open up the intake ports. It runs up to redline just fine, but it's out of breath by 5500. I've fiddled with carb specs but I'm pretty sure it's just that the T ports are a little restrictive. It would be fun to have it really want to scream past 6k. Overall, it's not a hugely different motor than when stock. It's still slow, just with a little more pep than before.

The crankshaft is your limiting factor ! You will not be driving at 7.000 rpm with a non counterweighted
crankshaft , you can , but the engine will have some harmonics and will not be smooth in my opinion .

Is this without any additional oil cooler?

For my 2.2T rebuild, I also had the machine work/squirters done as well as using a refreshed four-rib oil pump. From there I kinda went whole hog: 2.4 crank/rods, mod-S cams, 10.5:1 JEs, twin plug and a fender-mounted oil cooler. I did have a ground rule that I wanted to use the largest slip-fit cylinders possible without boring the spigots, so I chose to go with 87.5mm Nickies. (I waited until LN's annual sale to buy those.) Nickies run cooler than the iron and Biral cylinders. In my case the oil cooler was insurance for the high-compression/twin plug setup. LN also sells 85 and 86mm Nickies with 9.5:1 pistons, which would likely not require an external oil cooler. They are pricey, but I felt more confident using those over the AA Biral product.

Yeah -- I'm not even close to needing a cooler. Stock this is a 125hp engine, now it's I dunno, 140? As Henry said, you need to get up into the 160's to need extra cooling.

Below is the post of my 2.2T rebuild last year, with dyno results (flywheel). JB Racing agreed with Henry that for my application, aggressive street and occasional autocross, squiters were not needed. I"m in Florida and have had no issues with overheating.

"First, I would like to express my sincere appreciation for this forum and all who so generously share their knowledge and expertise. I have been a long time member. Although I rarely post, I frequently read and study the issues, solutions and commentary provided by others. I am a hobbyist, and the rebuild I just completed would have been extraordinarily difficult without the resources available here. Thank you.

I recently completed the build of my ’71 911T, 2.2. The machine work was performed by JB Racing in Tavares, FL, and yesterday I spent the day there with the completed engine running on the dyno. I can’t sing high enough praises for Jim Higgs and Dennis at JB Racing-they are professional, efficient, and their knowledge seems limitless. I recommend them highly. I am very pleased with the dyno results.

The engine: numbers matching ’71 911T, with the following performance mods:

Cylinders bored 1 mm to 85 mm; JE pistons with a measured ratio of 9.4:1
Cams: Solex grind by Webcam
Ignition: MSD Streetfire; stock Marelli distributor, with points
Intake: Zenith 40 TIN carbs, with 32 mm venturies; 145 main jets; 170 air corrector jets; 55 idle jets; stock emulsion tubes and stock idle air bleeds; fuel pressure 3.5 lbs
Exhaust: SSI heat exchangers, with Bischoff muffler

Results, (see table below for the final run): Horsepower, 173.3 at 6300 rpm (compared to stock of 125 @ 5800 rpm; and stock S at 180 @ 6500 rpm); 155 ft lbs torque at 5300 rpm (compared to stock of 130 @ 4200; and stock S of 147 @ 5200). The torque figures are somewhat misleading because this engine pulled over 150 ft lbs from 4100 rpm all the way through 5800 rpm.

Thank you again for all of the help!"

Thank you!

Doswald: those are very good numbers for a 2.2 engine, especially the broad torque. It must be a great street car.

More questions:

1. Did you do any work to the t heads to take advantage of the mod solex/dc30 cam? John at Dougherty is recommending dc15-102 which he says has slightly more lift than an e. This was based on my aim of a street only car prioritising mid-range. He said DC30 wouldn't give benefit without opening up the heads a bit (hope I'm not misquoting/understanding him). I know he is expert, just trying to understand why so many people seem to run DC30 on stock heads.

2. What alloy did you go for with the JE pistons - I have read people on here saying using the 2618 pistons is not advised due to fact the piston will expand faster than the barrel, and advise 4032 alloy. JE seem to make 4032 pistons but only with 10:1 compression. Will this be too high for my intended platform (ie single plug)?

Thanks

John @ DC is my go to guy but he generally suggests a "more" conservative route.


10:1 is too high for your application. Mild cams almost always increase dynamic compression so starting with 10:1 will be challenging. That said, it is relatively easy to trim the pistons to a desired dome volume (IE: lower compression).
The formula for milling 4032 pistons is:
Piston dome cc's to gram conversion: 1cc (volume) = 2.71 grams (weight)

You can use additional base gaskets to reduce compression. Additional base gaskets will increase deck height so it has to be considered a compromise.
Ordering a custom piston is always an option.

As for piston alloys: 4032 has a lower expansion rate which would match well with the cast iron or Biral cylinder. Cast iron has a lower expansion rate than Aluminum so you can run a tighter tolerance.
The 2618 expands more consistently with aluminum cylinders so they can be clearanced to take those higher expansion rates into consideration.

Henry, thanks again for your help. Everybody has been very generous with their time in responding. I am going to make some inquiries and then will post my final spec. Here is a sad photo that might go so way to explaining why I am rebuilding.


https://lh3.googleusercontent.com/pw...-gm?authuser=0

Gemanelan, the heads were rebuilt, but not modified; the pistons are custom JE pistons for a 9.5:1, id #322283. The measured CR is 9.8:1, 9.4:1 when the crevice is included. To clarify, the cam is the Solex grind, not the mod.

Pete, yes, I’m very pleased!

dho

Thanks doswald. Were these the 4032 alloy?

I built several 2.4 and 2.5 motors and dynoed them all in the same car, same exhaust system and on the same dyno. You can read the results i the link below.

https://forums.pelicanparts.com/porsche-911-technical-forum/1151593-dyno-summary-testing-early-2-4l-2-5l.html

john

Gmanulan, I don’t know the alloy. Perhaps you could search the id # and identify it.

dho

Wow, who knew? This simple formula allows you to order off the self pistons with entirely too much compression for your particular build then use this formula to custom machine them for a more exacting result.
Henry, is there a formula for 2618?

I bought the AA piston package and I'm happy with my choice. Instead of oil squirters I have notched my con rods on the big end, to squirt oil onto the piston crowns.

An experienced UK engine builder says the T crank is happy up to 7,200 revs.

I did the oil bypass mod manually. It was easy. And I got a 964 oil pump to supply the extra oil. To get it in I had to file down one of the case webs.

One of the most experienced engine builders around told me the 5 studs that it's most important to pull and put case savers on. I left all the original cylinder studs in.

I was also able to boat tail the case by hand with the long 13mm reamer previously used to clean up the valve guide bores.

Don't underestimate the amount of work involved, though. I did.

Sent from my SM-S918B using Tapatalk

Density equals mass over volume.

Sent from my SM-S918B using Tapatalk

2.8 g/cm³.

Hi - would appreciate some help choosing between these two sets:

https://aapistons.com/products/porsche-911s-2-2-2-4l-86mm-cp-p-c-kit-c-r-9-5-1-10-7-1

https://aapistons.com/products/porsche-911-86mm-je-piston-cylinder-kit-2-2-2-5

Am planning on DC30 cams but was going to leave my T heads stock. I would prefer CP pistons based on feedback, but despite the fact the CP pistons claim 9:5.1 (I think fine for my single plug application) they seem to have a very high dome height. Would I be better off with the lower comp JE pistons?

All aluminum alloys used in pistons have almost exactly the same density. In fact, almost all aluminum alloys have the same density.

The conversation about piston material is an attempt to source the correct piston design/material for a specific application.
4032 is generally better for cast irons liners because the high silicon content lowers the expansion coefficient. Full circle skirts will often create a quieter cold engine.
The quest about density differences is simply an excellent way to reshape pistons with having to CC each process. 4032 and 2618 are different enough to require a different formula to calculate CC based on weight.
After machining it makes sense to CC the final product.

http://forums.pelicanparts.com/uploa...1758148253.jpg
http://forums.pelicanparts.com/uploa...1758148253.png

First two sets of a new run of 95mm cylinders for 2.0-2.7 case. Obviously, a 7R case offers the best cylinder/head stack stability
They are in essence a 2.7 cylinder bored to fit a custom Ductile iron sleeve.
The completed cylinder is then Nikasil coated.
The special order CP pistons will run 4032 full, circle pistons with a 10:1 compression.
On a 66mm crank it's a 9.5:1, 2.8 and on a 70.4 crank it's a 10:1, 3.0.
The challenge was to source a set of rings that fit a ring stack I wanted in this low expansion piston and still be compatible with Nikasil coating.

http://forums.pelicanparts.com/uploa...1758151362.JPG
http://forums.pelicanparts.com/uploa...1758151362.JPG

When considering the density of aluminum variants I decided to compare the weight difference between the alloy used in making Mahle Nikasil cylinders vs the KS Alusil.

Of course both cylinders were decked to an equal height and both cylinders were fresh Nikasil coating. The results were interesting. The KS cylidner was 17.11 grams heavier suggesting a denser material. Almost 2% heavier.

Different manufacturers, probably different castings. How did you determine that each cylinder had the same volume of material?

Wow this thread went in an interesting direction. I started out as a newbie just wanting to learn about the basics, but ended up learning about different alloys!

Those 95mm pistons for a 2.2 look interesting! In the end I went for the CP s 9:5 pistons in AA Birals to go with my DC 30 cam choice. Based on some previous posts I found I'm a little worried about the consistency of the bore but we will see.

If somebody could help me work out my dynamic CR I would appreciate it. Also any advice on ring clearance when using the 2618 alloy in birals.

Wish me luck and thanks for the help.

Static compression ratio of 9.5:1.
Effective stroke is 2.29 inches.
Your dynamic compression ratio is 8.49:1 .
Your dynamic cranking pressure is 172.95 PSI.

A piston gave up on my stock 2.2T and I'm pondering what's the best path to rebuild the engine. I would like to get 150-170 wheel HP, nothing too extreme, and definitely a long lasting engine.
- Cost wise a set of Mahle motorsport 2.2S P&C costs 4500 Euros, and it comes with the great advantage of being all aluminum.

- Next option is AA biral cilinders at 700 Euros + 1300 Euros for a set of nice pistons, 2000Euros total. Add maybe another 4-500 if I get them nikasil coated as Henry suggests.

- Boring out my Cast iron cylinders is probably going to cost me as much as a set of AA biral cilinders, so I'm not sure it's worth it.

I was inclined to follow the Mahle route, but it would cost me 2000-2500 euros more, and it looks like most people here use biral instead. Is only cost the reason why people use biral over Mahle, or is there a technical advantage?
2500 Euros will buy me a lot of other parts, but I cannot make my mind of whether is worth it or not.

If I go the Biral route I could also go to 86mm bore and make a nice 2.3 engine.