Subscribed......welcome to the United States. Can't wait to see how this turns out.

 

Great news!
I'd be more than happy to see my little nephew hitting TXmile with the 4.3 conversion representing a great tuner like Todd Knighton from Protomotive.

Just want to start with the safety and stability measures considered explained before power.

 

Nice one Yousef. How will you manage without your beloved 911 until October?????

 

If you don't have a bucket full of cash, I would not go over 104 mm pistons and 80.4 mm crank or 4.098L ...... and this will still be expensive. I really can't imagine Todd going over 4.1L's. Then again maybe he has learned something new that I am not aware of.

Why ...... the room in the case for liners, crank swing and the piston rod ratio. You really want to stay above 1.6-1. If you spend a ton of bucks you can get a rod length of about 129.75 mm's. Without spending a ton you can get about 128+ mm's. What you really want is about 133.0 mm rod length. You won't get above 129.75 without changing deck height and timing chain length. To get above 128.0 you have to work with wrist pins, wrist pin height in pistons and true center location of wrist pins in pistons. There are many more things involved.

How do I know? I built a 82.4 mm stroke and 105.7 mm liner/piston. 4.338L motor. You are looking a big bucks and the knowledge to actually accomplish the build is very scarce. Be prepared for mistakes and a learning experience.

 

About a 82.4 mm stroke and a 105.2 mm bucket. That would give you 4297 cc's or 4.297L

 

Guy, unless a recent development occurred those above size Koro motors are not turbo charged. To my knowledge Koro never turbocharged our motors with a displacement larger than 4.2L.

 

What is the cost of such a project? Did todd send you an estimate?

 

thanks 7amood happy to hear from u ,good point regarding the safety am really not letting it am considering it 100% and i'll first start with the roll cage all i can find here and there is RSS and GMG and m looking for some thing i cant say better both companies are amazingly good but i want some thing more a full cage not half if any one have any thing in mind pls share it will really help

dianic i'll be good weather is already hott here and i'll be busy with my checkmate boat

what a pleasure having chad commenting on my thread and sharing his knowledge
first of all i've to say that in my project there's no place for mistakes cause there's a built engine in todd's workshop almost ready to go 4.3ltr doing a really great numbers 150+hp and 350trq more than what the 3.8 produced thats a ruff info pls dont take any of it as a fact but the engine is done and pls excuse my ruff knowledge in the end am a normal costumer im not a mechanical to know displacement and crank size details
we left the cost open and im sure it will not be a huge number todd's prices are extremely reasonable

 

wow, not faacking around anymore!

 

Definitely subscribed

 

They call Todd K the mad scientist for a reason

 

I really like the dedication to your Porsche! Best of luck and you're in good hands with Todd and Cynthia....

 

Chad,

You are correct, I know they are almost all non-turbo (and must be amazing on a track in terms of response). It was posted by way of an interesting aside that the 911 motor can be punched out to quite large capacity, but it is very rare that anyone goes over 4.0.

I would agree the optimum size for a turbo motor is only a little over stock ie 3.8/4.0. If you go too long on the stroke it's harder to rev really high and increasing the bores eventually leaves less metal and weakens the crankcase.

Guy

 

regarding safety requirements i'll first start with the roll cage all i can find here and there is RSS and GMG and m looking for some thing i cant say better both companies are amazingly good but i want some thing more a full cage not half if any one have any thing in mind pls share it will really help

 

Guy,

I believe if you examine the larger Koro motors you will find an extended case and heads.

At the risk of being proved wrong I will go out on a limb as say a piston diameter over 105.7 mm would be almost physically impossible. We utilized 105.7 mm pistons and had to engineer a hour glass type configuration liner with the strongest steel known/available. It took a special diamond hone just to finish them. The first hone just self destructed on the liner.

We stroked our 80.4 mm Arrow Precision crank to 82.4 mm by grinding for NASCAR oval bearings and using the offset to gain another 2 mm. The counters of the 80.4 crank leaves little clearance at the oil pump and areas of the case (after grinding as far as we dare).

I believe the piston to rod ratio which affects piston speed on the stock 996tt is 1.64 to 1. Generally, you want to stay at 1.6-1 or higher. This is dictated by rod length. If I remember correctly the stock 996tt has a rod length of 126 mm. A 82.4 mm crank would like to have a rod length of about 133 or greater mm's. Anything smaller reduces the piston to rod ration below 1.6-1. Using every trick in the book you can get just under 130.0 mm's rod length without raising the deck and lengthening the timing chain which is a very expensive proposition.

Every trick in the book to get longer rod length is small wrist pins which require stronger steel and black like diamonds coating, raising the wrist pin into the piston oil ring and offsetting the wrist pins in the pistons to a true center on each bank. Yes, each bank has a different offset from center (true center is not the center of the piston) which not only gains rod length but also makes more power as the motor is perfectly balanced.