germeezy1 ......... now don't go putting words into his mouth. He didn't say what fuel he was talking about. But for what it is worth, your 800 hp @ 1 bar guess isn't even close. And you are low.

 

It was more of a question, I guess I will patiently await the max numbers on pump and on race gas.

 

Anyone else want to offer their guess?

 

Our race fuel will utilize an octane rating of 120.

We have ever so slightly reduced the compression ratio and utilized a CDI ignition so as to attain maximum designed boost with the 120 octane fuel.

 

1288?

Greg A

 

Greg ..... I wish. Not at 1 bar. Your about as high as germeezy1 was low.

Greg, how in the heck are you doing? It's been awhile since we talked.

 

1000 RWHP? What will be the max on pump you think? I believe this is the most powerful 996 TT on the planet or is it?

 

At 1 bar we could use 91 pump gas with our compression ratio.

Bingo ......... Todd's prediction is 1000 hp @ 1 bar. The motor is designed for 2.5 bar. She is designed for 24 hours of ten tens on the track before a rebuild.

Most powerful 996tt? ......... well maybe if it doesn't take too long to finish. And then hopefully for at least a few hours. It will take someone who puts together a really built 4.7 to 5.0 liter Koro case, heads, etc. motor. They are available, however I have only seen NA versions. I do not know of a turbo charged one in our displacement category. We did not use the Koro stretched case, heads, timing chins etc. Our displacement is the absolute most attainable from a Porsche case.

 

We are late as usual. Have not got past the pistons and rods yet ...... here is the latest as of 6-10-09.

Good morning Chad,

Sorry for not keeping you further updated.

Spoke to the Piston manufacturer yesterday regarding the Pistons. Everything is going to plan and I will be there either later today or tomorrow to finalize the design. I have sent over the Rod spec’s and will drop off a drawing when I am there.

I have found a new Coil for the CDI system. The present stock Coils are Inductive and have the Igniter built internally. The CDI system requires only a “standard" coil. No Igniter. I have several to choose from, the installation length will be the determining factor.

I will be doing more on this in the next few days to get everything sorted and designed. I have asked Rob to send down the wiring harness so I can see what modifications will need to be done in order to run CDI Ignition. The benefits will be worth the time and effort. So much more energy is produced with CDI and this energy creates greater in Cylinder temperature. It’s this temperature that ignites the fuel mixture and produces greater levels of combustion.

There is a long standing debate over which is better. Inductive or CDI? I personally prefer CDI as I have tested both systems back to back and never have I found Inductive to make more power or better response over CDI. It has always been the other way around.

There are huge technical differences, but to keep it simple, Inductive can only produce Ignition energy based upon the Ignition Coils magnetic field. It is also limited by charge time. As soon as Inductive Coils are charged they have to fire. They cannot sit in dwell otherwise they will overheat and fail.

Based upon a simple calculation Inductive Coils require a certain amount of time to recharge. This is the dwell time. The Coils primary resistance and Inductance along with the charge current set the limit of the Coils output energy. The only way to increase this output energy is to either increase the charging current of the system or the primary Inductance. These increases add to the time it takes to recharge or the dwell required, thus making the engine speed a factor. The CDI system operates completely different. There is no dwell time as the additional energy created by inverting the power is stored in a capacitor. This energy is “dumped” by the system very quickly in comparison to an Inductive system. This high bolt of increased energy results is a lot hotter combustion, which results in more in Cylinder pressure and more loading on top of the Pistons. This is the extra Torque that you feel.

Many will tell you some modern race engines run Inductive. These systems are nothing like street car systems. The biggest difference apart from the parts and technology is you are limited to a 12V system. They use hundreds of volts to drive their systems.

Hope this helps.

I have also asked Rob to send down the Pauter Rod so we can see the dimensions of the BE. I am confident our Rod is smaller at both ends, lighter and stronger. The length is now set so we can start immediately on these once we confirm the BE dimensions.

Nh

 

And another from 6-12-09

Chad,

Went and discussed the Piston with Mike today. Gave him an Arrow Rod to measure etc. he hopes to get me a sample Piston very soon.

This Piston will need moch up. He is going to have the same pockets as the last Pistons. These need to be checked as you now have bigger cams and timing.

I told Mike we can get a Piston without pockets, do the P/V and then give him how deep they need to be. The way we measure and the interference is all on paper. We know the Cam lift at different Crank degrees, and we measure only the distance the Valve moves from the Valve seat to the Piston. If this distance is smaller than the Cam lift at the same Crank angle, the difference is the interference and we then add the clearance.

Nh

I am disappointed at not being able to meet my deadline, however I don't want any chance of destroying this motor due to a design mistake. This piston design is similar to the 962C design and the length of the rods and the lift of the cams only complicate the piston design. It appears we are about four weeks away from finally getting these parts finished and in our hands.

The crazy thing about rods is I now have a set of standard Carillo's, Ruff titanimum's, Pauter designed for OB's, Pauter titaninum's and now we may go to Arrow Precision to obtain additional clearance.

 

It's really going to be interesting what comes from this when this project is finished.

 

Sorry we are in the crawl mode. There has been a lot of effort going into the design of the rods. We have the correct rod length, however we are leaving no stone unturned in designing the lowest possible weight for our application in addition to providing the best windage, lubrication and heat extraction.

I think this will be completed sometime next week.

 

I just received this update from Neil at Performance Developments regarding our pistons. Once we have the file and Neil reviews it, production of the pistons will begin.

Hi Neil,
I just finished up the design on Friday night. I did a lot of “brain storming” to get this project figured out! I will ask my engineering department this morning to create a file to send to you.

 

I spoke with Neil today and he informed me he just got the files for the pistons today.

 

Here is a pic of the plastic mock up piston. This piston has cooling a la 962C design. The wrist pin is located up in the bottom ring and the skirts are far different than anything the 996tt community has seen to date.



Chad,

It’s absolutely critical that the new Piston and Rod combination all work dimensionally with your long Stroke and high lift Cams. We have designed the Piston to run with the new Rod length and the Cam lift and this entails the Piston crown thickness to be a certain thickness for the application. It is necessary before we commit to the Pistons and the Rods to moch up the engine and make sure we have all the clearances correct. This becomes expensive if we have to re do a part. Therefore, I am sending Rob a 1st article rapid prototype plastic Piston for moch up. We will print this up this afternoon and get it in the mail to him tomorrow. The print time is 7.20 hours.

There is a small cost involved here, ($420.00) but the alternative could be lower static compression if we get the Valve Pocket depths wrong, unusable Pistons and Rods that could be too long. It is so important to use all the tools available to do it right the first time.

I will send thro photos of the Piston as soon as it pops out of the printer. We will send back all of the engine parts to Rob so he can go ahead with the moch up. The Rod will need to be moched up as well. We have the clearance issue with the Crank to consider as well. The sample rod sent here apparently clears the Crank, but now we have a longer Rod with less angle. If we can stiffen up the BE of the Rod and make use of any additional clearance we may pickup from the new Rod angle we need to look at this. Everything here is been designed for maximum strength, weight reduction and performance. We have to make sure all parts work together.

As soon as I have the final Rod weight I will forward.

Nh