Jfrahm

Yes, I am back and had no problems with the SC kit over 1200 miles or so. My MPG was not real good but I am having an electrical fault with the MAF sometimes and I dealt with very cold weather, crosswinds and some poor driving conditions that affected that. Interestingly I found that slogging along at 60 led to worse MPG than 70-75mph cruising, the engine perhaps not in a sweet spot. I am usually in 5th at 60 in my other car (and not usually at 60 for very long) but in this case I was generally in 6th to limit torque due to road conditions, and hardly touching the throttle. MPG was not a concern at that time.

At normal highway cruise 70-80 mph, on 10% ethanol gas I got about 25mpg, which is fine but not as good as stock... but I have never done an MPG run in the winter before in a stock 968 cabrio and I know cold weather has affected my MPG in other cars. Plus the MAF issue might have made the car run fat sometimes if it defaults to a conservative fuel map. If I leaned anything, the MPG is not a lot worse if it is any worse on the supercharged car in highway mode. It could even be the same or better.

Otherwise nothing fell off on the drive, the belt looks fine, tracking is good, the annoying cold belt slip I get on my stock 968 is not evident here (due to the better belt wrap from the extra belt idler.)

The SC whistles a bit but sounds good in a jet engine kinda way. Sounds serious.
-Joel.

Carl Fausett

Answer to post 480: Our first kits were for the early Porsche 928, and those installs have been out there since 2003. Several of those are driven daily to work. I hear from them once in a long while - about every 3 years or so - for a new supercharger belt, but thats about it.

The Ferrari kits were the first to use the Raptor supercharger, and we brought the first of these out in 2006. All the Ferrari's with our Raptor kit on them are still in use today, even the very first one. He flew in here to drive his Supercharged Ferrari home to Utah in December, just like Joel did. I remember talking to him on the cellphone at midnight saying "Dude, you have to stop and rest sometime" he said no, he didnt want to, the car was just to damn much fun now!

Our experience with the Raptor was so good we opted to use it on the late-model 32v Porsche 928 kits.
Those we brought out in 1988. Our Stage 2 kit with the Raptor develops 506HP on the 5.0 Liter motor. The Raptor has a lot of capacity!

To this list we have added the 968, and the ne next car to receive the "treatment" will be the Mercedes Benz 350, 450 and 550SL coupes.

Every once in a while, you encounter a "problem install" I have one of them in the 928 area. Its usually from someone taking our engineered kit and modifying it. This owner - with very little understanding of how the system works as a whole - runs way too small a pulley, way too much boost, cannot supply a matching fuel load, and replaces a lot of head gaskets. He is off the charts, and does not represent our kit as shipped. But it happens.

wiseman

Carl,

There has been some scuttle on other sites that the 92 968 had some connecting rod deficiencies that were corrected on later models. Any issues with supercharging those 92"s ?

Carl Fausett

I would defer to those with more information about the supposed "defect" on that one.

In the 928 world, we have the spectre of the "2-6 rod bearing failure". It got started somewhere and it never has died. Under careful scrutiny, you discover that the only guys that have experienced a 2-6 bearing failure on the 928 are guys who take a stock engine to a DE or Track day, where it suddenly (magically) has become a 6800 rpm motor in spite of the redine being at 6500.

They bounce off the rev limiter (cuz now their street car is a racer) and throw the oil around in the oilpan without baffles or windage trays to keep it near the pickup. Then the pickup gulps some air, 2-6 overheat, and its Porsche's fault. The mystery 92 rod thing for the 968 may be similar.

Incidently - on 928's kept at or under redline, there is not 2-6 rod bearing failure, and on engines fitted with oil traps and windage trays, there is no 2-6 rod bearing failure.

Find out why they THINK there is a weak rod in only MY 1992 and dig for the truth.

And, BTW - there is a battery of Automotive Engineers who believe that low boost engines are gentler on rods than NA engines. The boost at the top of the piston creates a cushion to stop and reverse the direction of piston travel, preventing rod stretch.

At the boost level for this kit, we are not pushing the engine very hard. I wouldnt worry about it. If your going racing, get a good crank scraper, windage tray and Accusump installed and go have some fun.

Jfrahm

I have given the early 1R rods some thought and there is a recent thread here:

https://rennlist.com/forums/968-foru...-968-rods.html

They are the same rods as on the early GTS I think. As I also have a 92 968 and was thinking of supercharging it, the rods are a concern.

I suspect that detonation might have been an issue with those bent rods. Cheap gas or bad gas, hot weather, etc. Cylinder pressures under boost are higher but trying to compress the gas that's burning and expanding is going to be much much more difficult, it'd be much like hydrolocking.

I would personally try supercharging the 1A rod motor if detonation were kept in check with water injection, quality gas and frequent fillups. If you get gas at 1/2 a tank you never get more than 1/2 a tank of bad gas. Water injection has worked well for me in the past also.

I used to drive a Mustang that ran great on premium or midgrade but would ping noticeably on regular so I could usually tell if I paid for midgrade but got regular. This happened once or twice a year on average. Also a popular gas station chain in my area recently was investigated and fined for selling regular as midgrade or premium, so t happens. I could see high performance engines being damaged by that, particularly in hot weather.

I wish there was an easy way to see or log the spark angle or knock events on the 968.

Anyway this info being worth what you paid for it, I'd give it a try... but if you had any other reason to go rooting around in the motor you might as well change the rods too. If you are going to do the head gasket and rod bearings why not change the rods?

-Joel.

rgs944

I am just planning on that extra zip (or high if you will) everyonce in while in going from 30 to 90 on the open road. Not going to race with it. The supercharger getting to the rev limit should not be an issue as long as you do not put one of the cheap increase rev limit chips in. I also like Carl's thinking of keeping the boost at a moderate level. I think what it boils down to is that if you are going to race any engine or car to the limit on a regular basis you just need to expect periodic failures. Look at the # of $30,000 race engine that only last maybe 2000 miles. If all you do is get a heavy foot every once in a while when street driving most well designed and made engines should last a long time. That is just my theory for what it is worth.

Todd951968

Crap, I have an early '92. I was seriously considering a SC sometime soon. I may need to rethink that now. That's sad. I don't have the budget to rebuild the motor with new rods AND get and SC.

Carl Fausett

Todd,

I would not over-react to the reports of weak rods in '92. I explained why in post 484 above.

This is a very safe kit with low boost pressures. I'm sure you will be fine.

FRporscheman

The early 92 rods are different, according to a Porsche tech bulletin, than later 968 rods. Late rods are reinforced by the shoulders, near the heads of the bolts. I believe all the rods are forged though, and that's the most important thing IMHO.

The way I see it though, even if you have measly cast rods, they will function fine until something goes wrong, like detonation. Then, you might bend a rod. But if your rods are better, they will still probably bend, just bend less, and it will still be a nightmare to repair. So I'd just use whatever rods you have, and use the best fuel you can find.

I have never heard of '92 rod failure.

rgs944

Any time you modify any car to increase the HP there are going to be some risks. From the information I have gathered so far this seems to be a safer bet than drastically increasing the HP on a 951. It seems that about half of the 450plus HP 951's out there have had serious issues within the first few years or first few thousand miles. I realize a lot of these are race cars so maybe it is just that if you push any car to the limit all the time it is bound to have trouble. This is just my theory but I believe that you should be able to safely tune about any car to a 30% increase in power without sacrificing much reliability. Go over that and I think you are asking for trouble in the long run. Car makers will usually overbuild somewhat to account for future deviations or problems, but they do not build cars expecting the owners to increase HP 100% or more. Increasing the HP of a 968 by 70 or so HP and not rodding the **** out of it all the time seems like it should as safe as can be expected of any mod. As Carl has suggested, if there really is a problem with the rods in the 92, this kit might be better for them than the stock setup, who could ever answer that question accuratly? I am always skeptical of something running harder and it lasting longer but I have certainally seen stranger things in my days. With 25 or 30% more power I believe the 968 will be the perfect street car for fun so I am definitly getting the kit on this year unless I see conclusive evidence to think this will harm my engine. I will keep an open mind and look forward to conclusions and information other members can add.

odurandina

any Porsche 4 cylinder pushing over 375 hp is a high-strung bomb waiting to go off.



Carl, just a suggestion that you might go back to the first post and add the video clip.

i love the sound. http://www.youtube.com/watch?v=nr1F_z8bi1I

Vilhuer

Its not early '92 rod problem. Its before late '94 MY rod problem meaning even early '94 MY cars have weaker 1R casting number rods. There has been boosted early rod cars before and rods in them have worked. If engine is opened to build it foor boost its better to change rods to aftermarket set anyway so it doesn't matter which versions are in originally.

Carl Fausett

Here a few pics of the first in stall in a 944 S2. This S2 has a 968 engine in it.

As expected, the distance between the engine front and the hood latch is less on the S2, and these pics show the conflicts: 1) hood latch, 2) headlamp mechanism.

The customer has decided to replace the hood latch with hood pins (I recommend and use the Aerocatch at www. aerocatch.com ) and he has decided to replace the hidden headlamps with projector hedlamps with a plexi cover.

Carl Fausett

After the hood latch was trimmed out, the supercharger fell right into place, and over the top of the radiator as it should. The customer reports its easy from here.... and that he has more room for the cold air tubing and even a larger air filter than the one I provided (designed for the 968).

More photos and info on the S2 install will follow as they project continues. I am not doing this project in-house (as I have mentioned before) but I am assisting the owner from a distance.

Jfrahm

I read about a 914 that had headlights that were converted to spring up when needed and then had to be pushed back down by hand, like a jack-in-the-box. I wonder if that is a kit and it it could work on the 944 to remove the headlight motor, transmission, etc.?