I agree. I've never heard of anything with similar displacement making power like that at 14 psi.

But, I'm open to the possibility....

 

Scott's motor has be quite reliable. Just snapped 3rd gear today at road america so you may want to consider tranny and clutch issues also. It needed the gt2 slave upgrade anyway

 

I am waiting for Neil @ Performance Developments to tell me when he will be shipping the motor to SCarGo Racing to install the motor, prefab the piping from the IC's to the CF inlets on the intake. SCarGo Racing will then ship the motor to Todd at Protomotive where Neil and Todd to break in and tune on the engine dyno at Todd's facility.

 

Scott,

Not quite 4.4L ....... do the math 105.7 mm buckets and a 82.4 mm stroke with a 1.587 piston to rod ratio. There is a little more than just extra displacement at play with this motor to develop 1000 ponies at 1 bar.

 

CJV,
so you are finally done with the motor after 5+ plus years ?

 

unvmy996,

Not exactly. For those who were following the build we were testing it awhile back when upon breakdown for inspection we found issues with certain bearing.

We have since reassembled the motor, changed the intake, added six 48 mm TB's and added dual injectors. The engine management has also been modified.

No matter what the final result ........ no more motor mods. Whatever the final result is ........ that's fine. We just may see 1000 ponies with a little less than 1 bar.

 

Got it. I'm comparing it to motors with similar displacement and every breathing mod imagineable. I don't remember seeing any with similar displacement that produce that amount of HP at only 14 psi.

I'm not saying they don't exist, but I don't remember running across any in person, online, or in tuner mags over the years.

Good luck either way.

 

Thanks Scott ....... I will only be too happy to prove it to you.

 

I'm looking forward to it, along with a lot of other people. Can't wait to see/hear numbers.

 

A littel bird told me that we can go to 5.0liter on 997tt engines

 

Chad,
i see, well i have been following your build for a LONG time.i thought maybe that it was go time. i mean at one point you need to stop and think when is enough enough ? i mean ,its been a long *** time in the making , i think you should do as you said and say enough and enjoy it. i know what you guys did and found out will help the community with the big engine builds so props to you for that .

im excited for you . and i cant wait to see the final resaults .

 

yeah ....... your little bird is Koro out of Germany. www.koro.de Been there and done that.

The 996tt and 997tt are basically the same. I have discussed and examined Koro. They claim a 112 mm bucket and 84 mm crank to get 5L. There isn't enough room for 112 mm liners unless you siamese the liners. Sort of that you have to lengthen the case and the heads. Regarding the crank, we could not get a crank in a Porsche case any larger than 82.4 mm because of case wall and oil pump clearance problems. Then again changing the case dimensions will work.

Finally, a stock Porsche has a rod to piston ratio of about 1.64-1. It starts to get on the outer limits with a ratio below 1.60-1. KA has a ratio of about 1.58-1 ......... this is a result of rods with a length of approx. 130 mm. I believe stock is approx. 126 mm. I would have liked to had 132-134 mm. The only way to raise the ratio and reduce piston speed is to lengthen the rod length. Surprise ...... to get to 130 mm required offsetting piston center on each bank, raising the wrist pin into the oil ring and reducing the diameter on the wrist pin. There is no more room for any longer rod length. Now imagine the rod length required for a 84.0 mm crank.

You go too much below the 1.6 ratio, your pistons will travel too fast, you drastically lower your red line and you motor has a tendency to go boom. On the plus side your torque will be in never never land.

Short of raising the deck height you can't gain any more rod length. Now we looked at raising the deck height with spacers or billet custom case but alias you have issues with the timing chain. Talk about throwing money into a deep dark hole.

Finally Koro has built large displacement 996 motors up to 5L, however they are normally aspirated. I don't believe you will presently find a turbo 996/997 motor larger than 4.3 or 4.4L.

This is as I know things today. You have to remember in 2001, 450/500 hp was king on the street and a little bit earlier Porsche won LeMans with a staggering 600 hp. Everything may change tomorrow. Hell, throw enough money at it and it can be done, however be laying down when you get the bill.

 

I kept thinking we would max this case out. Back in April 2004 when my car was a featured article in Excellence we had a whooping 640 hp and a bit less torque. At the end of the article I told Dave Colman, the writer for Excellence that we were going to build a 1000 hp motor. He all but said I was crazy being the most power motor at the time was just over 800 hp.

My point is these motors are probably about as far as they can go now with making a custom billet case.

 

great thread. how reliable can a 500-650 turbo be on stock bottom.

 

Very reliable.