kellyk

[QUOTE]Originally posted by CBass: "Are there any SCCA classes a 16V 968 turbo could race in? Also, what method of lowering compression did you use, and did you o-ring or sleeve the cylinder?"


SCCA rules make it very hard for turbocharged cars like mine to compete. They really want NA cars as it is a lot eaiser to keep parity between the differnt manufacutures and models. I still havn't run an SCCA event and I have got about 10,000 opinions on how the car would be classed. Probebly will end up running with the LMP 900's! Currently running POC in V1.

Originally we were going to machine the pistons to reduce compression, however there wasn't a lot of piston mass to begin with on the factory Mauhl pisons and with the amount of HP we knew the engine would make we decided to shorten the rods instead. I got Carrillo to make a new set about 1.5 mm shorter which gave us about 8.0:1. I'm glad I went this way as now the bottom end is absolutly bulletproof.

We used a wide fire ring head gasket and Racewear head studs. I keep the boost regulated at about 15psi as I blew the head gasket when my adjustable boost solenoid failed. With 15psi I am probebly putting out about 500HP which is plenty for now.

Vision Motorsports recently built a full-race version of my motor with a larger intercooler and slightly larger turbo and they are getting about 600 HP out of it. I am thinking about doing this as well, but it is really expensive as I will need to install a complete one-piece front clip to handle the twin radiators, oil cooler and giant Kokeln intercooler. They are also using a Motec in place of the Link computer I installed.

CBass

Yeah, I am going to be building a 968 turbo, based off of a 924S. I am going to use FG panels all around, and try to get the weight down to around 2500 lbs. I want to run around 10 lbs off boost on the street, it'll be hard to put down much more than that

So tell me about this Link system. I was just going to run a turbo chip with the stock ECU... I am working on an EFI system, designed from the ground up. However, this is going on my indestructable smallblock Ford, not the possibly destructable and definitaly expensive 3.0L

kellyk

I'll tell you what I know about the Link computer.

Because the 951 OEM Motronic could not control the variable boost and vario-cam timing on the 16v head so we had to use a entire engine management computer. Prices on the Motec started at $10k. Link was supossivly started by some engineers who worked at Motec and saw a market for lower cost systems. The system is not quite as sophisticated as Motec but still allows something like 160 different fuel maps. It will run the vario-cam, boost control and the twin knock-sensors on the 968 engine. I don't remember the cost but it probebly about $2-3k with the software.

Re-configuring the wireing loom was the biggest hassle. I still don't have either the tach or a speedo working yet. Mechanically the conversion works well. The electronics can be problematic.

If I find anything on the Link system I will post it or e-mail you.

Brian Morris

Kelly,

Great info on your motor. I have a 968 motor in my garage which I plan on putting in my 951, but I've been dragging my heels.

I've heard a couple people mention that Vision says that you can reduce the compression by using shorter rods. I've read many places (written by engine builders) and talked to a few engine builders who all say this is a bad idea because it opens up the squish area causing more detonation. Do you think your motor is anymore prone to detonation and/or back off the timing a lot?

A year ago I started on the "I'll just get shorter rods" route and was talked out of it. It certainly is the easiest thing to do and I would go that route if I felt it worked OK. I'm looking to build a motor that isn't super high boost/HP - probably like yours around 15 psi. As you said going to higher boost/HP you need to deal with lots of cooling issues.

Any info would be appreciated.

Thanks.

--Brian Morris
89 951

kellyk

I am certainly not an engine builder but I can testify that pre-ignition has never been an issue with my motor. One of the advantages of the 968 is that it has twin knock-sensors whereas the 951 only has one. The computer can much more quickly establish pre-ignition begining and instantly retard timeing or cut of fuel flow.

My car runs great on 92 octane pump gas with no overheating although most of my driving is on the track I usually pump 110 leaded. This definitly solves pre-ignition issues!

All I can say is Vision did an incredible job on my motor, especially considering it was one of the first (if not the first) 951/968 turbo swap in the country using the 16 valve head and variocam. I am halfway through my third year of track use without a single major motor problem. I think if using shorter rods were really an issue, something would have failed by now.

One advantage to shortening the stroke is how easy the motor revs. I took about 14lbs of reciprocating weight from the crank and another 10-12 from the flywheel. This thing winds-up like a two-stroke superbike!

BTW, I am running a stock 951 radiator and intercooler (although the turbo is oil-cooled) and have had no overheating problems even when racing.

odurandina

968s rule.

MichelleJD

Wow. Is this the first thread ever from the RL 968 boards?!

flwbyu

Nice find from the past... ;-)P

odurandina

doin' what i can to help our immortal ancestors stir the pot and generally cause trouble (rest their souls).

333pg333

I would have bet my house that OD dug up this thread when I clicked on it and saw 2002...lo and behold...

odurandina

and i'll see to it that no good deed (that is, speaking good of the 944) goes unpunished on this thread.

odurandina

.......

MB968

So what ever became of the turbo'd 968 engines mentioned in the thread. How many of these were ever done?

And while I'm asking, have there been any/many roots type s/c's installed on 968 engines?

odurandina

there's a lot of engines. many of which are in 944s.... this is mainly due to the enthusiasts having so much money in their 944Ts, but at some point experiencing an engine failure.... and since already having a good car w/ suspension, brake upgrades, etc, and already having many of the necessary turbo parts, it's highly desireable to upgrade to the 3.0. but several of these engines have been done for 968s as well.

there is a 3.0T registry on the 944T forum where people show their projects.

and the first post keeps track of the number of completed engines.

https://rennlist.com/forums/944-turb...-registry.html

MB968

Thanks, I'll check it out.