AndyNorris

Hi,

Can anybody tell me of their experiences of Supercharging of Knoxville... good or bad.

I am especially interested to hear from anyone who has used their twin screw whipple (auto-rotor) conversion on a 3.2 Carrera.

Thanks

Andy

graham_mitchell

search for SoK or Knoxville across all the forums and you will find many related threads. At least one Rennlister has had the full Sok kit installed on a 3.6 engine. Very nice...

Jim @ EuroWerks

I have installed the TPC SC kit on a 993. HP went from 300 to 340. They didn't tell me alot of things like emmisions hook-up, key info on belt set-up. It turned out pretty good. But I'm still wondering if its worth it. You could sell your car put the money you were going to spend on the SC and buy yourself a nice 911TUUURRRRBBBBBOOOOOOOOO!!!!!!! Then you could have more performance withou hurting the value of your car and there's lots of mods from there.

JW in Texas

Andy,
The TPC & SoK kits are very different. More power & more $$ with the SoK route. I had a highly modded 930. No contest with my current SoK car. It would smoke my old turbo! The turbo was like going from Yugo to F16 at about 3000 RPM & that was after mods to get the boost to even come in that low. With the supercharger, the power is on all the time. Kind of like a Chevy big block stuffed in the back of a 3000 lb 911. Very linear thrust that will pin you to the seat. Sure to put a grin on your face every time you hit the gas

AndyNorris

Hi JW,

You are the kind of person I would like to talk to. You see I have an SoK kit in my car.

Your current SoK car, is it a 964 or an early 911? Are you using an Paxton blower or an auto-rotor one?

My car was originally a 3.2, but had already had a RUF 3.4 conversion and was putting ot 250bhp.

I had the cars compression ratio lowered to 9.0:1 and the SoK auto-rotor kit installed in March last year. The power went from 250 to 320, with fantastic torque all the way through the rev range.

The engine oil teperature went up a little, but nothing excessive. From March last year to June this year, I had no problems, but in late June the supercharger siezed up having covered just 6000 miles from the time of the conversion.

My questions are (if you dont mind)?:

1. How have your dealings with SoK been? Have they been helpful? I have had to deal with the warranty claim with auto-rotor myself as SoK have not wanted to get involved (I am in the UK). At the moment they are not even returning my emails.... who did you deal with at SoK?

2. What boost pressure are you running at. Mine is 8psi.

3. Have you taken any additional steps with charge cooling? Are you running a large or small intercooler?

4. Have you done anything to get cooler air to the engine air intake? As it is at the back under everything I am a little concerned about the temerature of the air going into the engine.

Auto-Rotor have come back saying that the charger failed due to overheating due to excessive boost. At 8 psi I think that is very unlikely. Having paid a fortune originally, a furtune to get the car back on the road my worry is that there is some inherrant problem somewhere else and that the potential exists to have another failure. Any light that you can cast on any of this based on your real world experience would be very much appreciated. I have been really happy about the car with the supercharger installed but can not afford to keep putting good money after bad.

All the best


Andy

JW in Texas

Andy,

I can't help you much but here goes:

Andy Sorry, I am no help on this one. I did a motor swap with a friend of mine before he moved to emissions hell (California). He was going to sell his RSA but we swapped my stock motor into it instead so he could keep it. My motor was one of the first SoK motors.

I am running 8 PSI also with 9.0/1 & an EFI control box.

I am running a BIG intercooler. I think it's almost mandatory. This could very well be where part of your problem lies although it is downstream of the blower so I don't know. It does reduce a lot of the heat though which could impact blower life through overall engine compartment temps. Just a guess.

This is a very good point & I have been working towards a solution. You are right, that K&N cone filter in the back of the engine compartment sucking all that hot air in isn't good for the blower at all! I just bought another tail that will get more air going through the intercooler & also allow me to move my intercooler back & level it off some. I am then going to fab up ducting & an airbox at the leading edge of the intercooler to get cold outside air to the intake. Check back with me in a few months & I will update you on progress. The tail is painted & ready but Club Race season is keeping the Supercup prep at the top of the priorities list right now until the season is over. I may try & get some work done to it between the Hallett race & the New Orleans race the end of November. I'll try to keep you updated but if you don't hear anything in a few months, drop me a line.

Even with some of the minor issues to work through, I still wouldn't trade the SoK motor! Good Luck & keep in touch!

AndyNorris

Hi JW

Thanks for taking the trouble to get back to me.

I guess we are thinking on similar lines (which is reassuring). The reason I have been trying to get through to Sok is to get their larger intercooler.... I think it should have been supplied with one in the first place, but I guess I am going to have to source one in the UK. Have you ever done anything with charge cooling?

As with you, I have got a bigger engine cover that is not on the car. which I will try to attempt to get some ducting for the air intake. I will also stay in contact with progress.

Absolutely superchaging is a fantastic way to go, I toyed with going for a RUF turbo conversion, but the way the supercharged motor pulls out of the slower corner.... there is no substitute!



All the best

Andy

johnfm

ANdy

I have a couple of e-mail & phone numbers form the SoK guys on my work PC. There are also a few places in the UK that custom fabricate intercoolers.

I will try to dig p the details for you.

AndyNorris

Thanks John, that would be much appreciated

agentpennypacker

What did the supercharger on the 3.2 cost you? Were your hp figures at the flywheel? I thought the 3.4 ruf kit would put out more than 250 at the crank.

Chaos

Do you think one would hold up under 8-10 track events a year?

AndyNorris

By the time I finished, it was about £7000. The kit was about £5000, but I made the mistake of initially going for the smaller intercooler, which I have subsequently replaced with the larger size. Work needs to be done on the engine to get the compression ratio down. The easiest way to do this is to put 1mm base gaskets on the barrels. (this will also help to check out that the engine is in good condition without having to break open the crankcase.... I needed new valve guides anyway).

In terms of power, I am still diasapointed, 320 bhp is the adjsuted flywheel value. The supplier claims 400 bhp, but I have so far not got near to this figure.

RUF claim 260 for their 3.4 kit, once again it never quite made it, but at least was closer than I have got with the supercharger.

AndyNorris

I only use my car for racing and track days now. The first supercharger failed after less than 6000 miles. Although I have never got to a satisfactory answer as to why it happened, I believe it was due to the combination of heat (small intercooler) and the length of time you spend at full throttle whilst you are racing).

With the second, I also at the same time changed to the larger intercooler, moved the air intake that SoK provided, so it is getting cooler air. The Auto Rotor OA3150 blower that is provided, also allows for an oil feed to be taken through it from the engine rather than as a closed resovior (as suppled), I do not know if SoK can provide the additional hardware, but for racing/tyack days I think it would be a good idea.

In general, I still think that supercharging is the best way to go. I get the same or better punch out of corners than much more powerful normally aspirated or turbo cars can provide. Unfortunately (for me), I am still not getting that power to last through the whole rev range, at 4000 rpm I am starting to loose boost, by 6500 rpm I have gone from 8 psi to 4 psi. I do not know if this is inherrant with this conversion and blower or a problem elsewhere (I suspect the latter), but have found out that supercharging is somewhat akin to rocket science... tring to get a straight anwser to a quesion or more information out of the manufacturer or supplier has been like pulling teeth. I am still hopeful however that I will enetually get to the bottom of the outstanding issues.

MPB993

Hello Andy,

although I dont have a SoK kit I do have a TPC kit where the manifold pressure reduces with rpm as for your setup. I have determined that the engine air flow efficieny improves with rpm as a result of the cams used on my 993. The TPC roots blower has a linear flow rate over its rpm range hence the flow divided by rpm remains relatively constant. Hence as rpms increase the engine wants to flow more but the supercharger remains at constant flow. Thus the manifold pressure reduces with rpm. The system performance of the supercharger and the engine are now governed by the intake characteristics of the supercharger and not so much the engine + cams. Athough parasitic loses of driving the supercharge reduce with manifolds pressure. What this all means to my setup is that torque remains relatively constant across the rpm range even though the manifold pressure reduces. I dont know if this might explain whats happening with your setup. I have spent the last year looking into this.

Cheers, mark.

MPB993

Sorry should have said volumetric efficiency of the engine + manifold+ cams increases with rpm. But the volumetric effiency of the supercharger doesn't increase as much hence the pressure drops.