2.2t rebuild questions

[gmanelan]

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

[Henry Schmidt]

Here are few thoughts highlighted in red.

Originally Posted by gmanelan

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) What is this "Bible" you refer to?

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 The 2.2 911 T was a 5400 rpm engine. 7000 rpm is an upgrade requiring a little thought.

Am going to do a total rebuild so:

- add piston squirters Cast iron cylinders do not require oil squirters.
- Oil bypass mod By pass mod is useless without a 908 style pump
- Case savers smart but not necessary

I am inclined towards a short stroke and reuse whatever I can so thinking
- keep t crank the crank is fine as are the rods. ARP bolts are generally recommended but ARP does not make a 2.2 rod bolt. Some rod modification is necessary to install 2.4/2.7 bolts.
- refresh t heads You might want to open the intake ports to enhance volumetric efficiency.
- double springs ?? all 911 engines come with dual springs, depending on cams, stock springs are good to go (after testing)
- bore out my iron cylinders to 86mm (have read some saying I can't and some saying no problem) You can not bore 2.2 T cast iron cylinders out to 86mm. The cylinder wall get too thin. If you goal is higher compression I would look to install Biral 86mm cylinder. 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.
- - je pistons (9.5:1) There are many choices for after market pistons and JE will work fine . You might target 9.0:1 to protect against potential detonation on street gas. Hot heads, high dynamic compression (mild cams given your desired rpm range) can offer a challenge since your goal is "no cooler".
- e cams (or DC30? is this worth it given I am sticking with t crank so wont be high rev motor) DC 30 is a Mod Solex and is a nice compromise. Solex cams are also a favorite of mine for your projected
- Weber 40s IDA carbs or preferable to the IDT that came on many 2.0, 2.2 and 2.4 T engines.

- was hoping to avoid adding an oil cooler - interested if you think possible with this setup Whenever Porsche designers came up with a formula that made 165 hp they generally added a cooler. OF course the 75-77 2.7 cars were an exception....a mistake for sure.
That said, high days and spirited driving will generally facilitate a front cooler. Once again, head temps created by your final configuration will be key.

Thoughts?

Thanks in advance

Cheers

[PeteKz]

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.

[Henry Schmidt]

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.

[gmanelan]

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

[911 Vintage Par]

Originally Posted by gmanelan

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.

[gmanelan]

Originally Posted by 911 Vintage Par

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?

[Henry Schmidt]

Originally Posted by gmanelan

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, play 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.