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