Winter Projects Update...

[Guest]

Finally got my car back today. Its not finished yet but its ok to take to Spa next week and the boys at JAZ pulled out all the stops to get it done. Great stuff, really appreciated. They did 8am to midnight days this week.

First off, the new exhaust looks good. The muffler needs some polishing and the tips are a little thin but it looks pretty good. I just snapped off the photos after I got home and while there was still some light. This is as much as you can see of the SSIs from the back.

 

[Guest]

You can't really see the muffler but at least this gives you some idea of the look from behind. The two tailpipes are not quite the same length - the first thing my wife commented on as she humoured me by pretending to inspect the new toys.

BTW, this is a muffler from MB911 off the Pelican BBS. Landed in the UK for under GBP300 and it is a very lightweight muffler with little restriction. Apparently uses aircraft muffler technology. The welding looks to be good quality and it is 100% stainless. My only concern is that the pipes look too thin to support bolt on cans if I needed them for noise limits - more on that in a moment.

 

[Guest]

So what does it sound like? Steve at JAZ didn't paint a flattering picture - sounds tinny and it will resonate. Oh dear. When I collected the car Dave was much more enthusiastic, but then hes a fair bit younger as well.

What do I think? It is freakin loud !!!

Yes it has some resonance, though not evil resonance, from say 1800rpm to 2800rpm. I found myself staying in second in 30mph areas and downchanging to 1st for roundabouts to stay over 3000rpm as that is where it starts to sing. Over 4000rpm and it really howls.

I never believed people who say a muffler can make a 911 sound like an F1 car - and I still don't. But what it does do is give an overlay more like a 355s metallic howl. Very nice. I have still yet to go over 5000rpm (more on that later) so the full joy is yet to come.

The best thing was that in stop and start traffic a young teenage girl (with her father) leant out the passenger window of her to car to smile wave and give me a big thums up. How cool is that. I also caught a couple of Eurobox drivers winding down their windows to get a better listen.

My wife of course was somewhat disparaging. She said she thought is was some "bogun" car until it reversed into the driveway and she realised it was me! FYI, a bogun is kiwi slang for the lower class of petrolhead who drives a V8 ute, has a mudflap haircut and has trailer trash wife and kids. Highly flattering. She does have a point as it idles pretty poorly (more on that later).

Time for another picture. This time of the engine bay with backdated heat. It looks so clean without the heater - and also much lighter. Again kudos to JAZ as they had all the tinwork plated and did a super job on getting this neat and tidy. They also got the footwell heater blowers to work, which is a first since i have owned the car. I just assumed they were kaput.

 

[Guest]

So why the 5000rpm limit and the strange idle? Well, while we were in there, we decided to rebuilt the engine as well. So its still running in the new rings and new cams, top end.

The cam choice is a 993 Supersport grind and the engine has 993TT rod bolts and race valve springs with TI retainers, so it is good for 7000+rpm and the cams should make good power to 7000ish unlike the 3.2 cams or even 964 cams that fall away much earlier.

It sure feels like it wants to rev. At 5000rpm it feels like it is just climbing into the power band. It might have lost a little midrange but it is too early to tell really. I won't hazard a guess on hp until it is dynoed and remapped but it feels promising. The guesswork at JAZ threw up some pretty impressive estimates so fingers crossed. Bottom line is it feels strong and sounds ballistic. Now I just have to hope the noise tests are ok.

The character of the engine has really changed. The car feels more like my friends 2.8RS motor that makes 260hp and revs to 7500rpm. It doesn't come on cam as strong as that motor but it feels more like a motor that really wants to rev. It could all be just the sound playing tricks on me though as the exhausts on the two car are very similar.

The idle? A consequence of the cams. It is a really lumpy, cammy idle that sounds very race car. Certainly conveys a certain intention and makes heads turn. I am just happy it idles at all as some people told me it wouldn't idle.

Fingers crossed it all holds together and survives Spa - forecast rain!!! - so I can report back on how it all goes when the full rev limit (6840rpm for now) is available.

Last picture.

 

[Guest]

PS - its not finished yet either.

It was supposed to get a lightweight flywheel and a higher clampforce clutch but we struck issues over that and are having to rethink it. Hope the old clutch is good for the next few days....

 

[bones]

Nice one Richard hope you really enjoy the new engine. I feel like you are a kindred spirit. Incidentally you couldn't be more right about the idle on tuned 911s , they sound like a bag of spanners.

 

[sheep911uk]

looks like a great job,i am thinking of getting a twin outlet exhaust how did you modify your bodywork to fit the twin outlet
Thanks

 

[Guest]

cut the valence. I will post detail pics in due course. Remind me if I forget or send me a PM.

 

[IanHighfield]

Good write-up and pictures as ever - enjoy Spa and may get to meet up at the Weltmeister Dyno day.

 

[plhorner]

ORIGINAL: Richard Bernau
Time for another picture. This time of the engine bay with backdated heat. It looks so clean without the heater - and also much lighter. Again kudos to JAZ as they had all the tinwork plated and did a super job on getting this neat and tidy. They also got the footwell heater blowers to work, which is a first since i have owned the car. I just assumed they were kaput.

OK Richard, you were right, it does look a lot better with the heating system backdated. I might well consider it myself and loose the cumbersome std. blower and ducting.

 

[Guest]

The heat output is also very good without the blower. I will post more info later but I think the engine work gets a qualified thumbs up. I don't think there is a huge power increase yet but then given the continuing high oil consumption, I don't think I am yet fully run-in/bedded-in. My car seemed more or less as quick as Andy Tim's chipped CS on the long straight up to Les Coombes at Spa so its quickish. I will try to get a report on Spa done over the weekend.

RB

 

[Bazgillie]

Richard
Where did you source the tin ware for the heater ducting? Is it a standard part? Its a mod I would like to do to my SC at some point.
Baz

 

[bones]

I bought mine from breakers Baz but it's still available according to my parts CD.
Incidentally a new parts CD is available from your OPC in .pdf format for about £7.00, covers all vehicles from 356 up to the present day but always check if unsure when ordering that you are buying the right part and it is returnable in case you've made a cock-up. If the parts man makes a cock-up they take the responsibility.

Parts CD Porsche Part 000.043.400.05

 

[Guest]

JAZ got most of it for me.

I got the LHS duct from a breakers and then had to take a rubber mallet to it to clear the distributor. You can order a 930 part new from a dealer which clears the distributor but its about £100. The RHS duct you can buy for much less - again, from the dealer. My tinware was re-used and replated (I think it was re-used anyway). The rear piece of tin has a big hole in it that the old heater blower went thru and JAZ just made a little shiny plate to cover the hole. You can buy most of the old backdate tin from the dealers if you want to do it that way.

I can't find my list of the part numbers but I just copied it from Pelican after doing a search for "Heater Backdate".

Richard

 

[Guest]

Just a couple more thoughts. I have been corresponding with the Muffler manufacturer regarding the noise level and he thinks a lot of it is due to the cams so other 3.2s would not (and have not in his experience) been so loud or resonant.

Anyhow, this is how I described the fitting and sound to him:

"Yes, it fitted just fine. We made up some straps for it and it bolted straight on. If I was to be hyper-critical, I would say that it is slightly odd that the LHS outlet is longer than the RHS and that the RHS is also slightly higher.

I like the sound. It really screams at high revs. There is a real change in sound when you go from idle past 1800rpm where its very loud with lots of bass and what I described before as reverberation. This continues thru to 2800rpm where it quietens off dramatically and starts to go into the "screaming phase". It is fairly quiet thru to 4000rpm just steadily building to a crescendo. Cruising speed is determined by keeping it between 3000 and 4000rpm and picking a gear. On overrun and light throttle it pops and bangs in a way that I think is great with that nice hollow sound that only stainless systems seem to have.

I have never really believed people who have in the past described a muffler change as creating a sound like an F1 car or a Ferrari. Now I wouldn't go so far as to say it sounds like as F1 car, but there is a certain similarity to a Ferrari 355 once the revs are past 3000 - and I say this after riding in a 355 for a few laps while at Spa then jumping straight back into my car.

I guess it is relevant that my car has 993 Supersport cams in it, which give it a very lumpy, cammy idle and maybe make it sound a little different to a std 3.2 once the revs rise. The engine has only just been rebuilt so its yet to be remapped and I suspect the mixture is off a fair bit, but that should not really change the sound. It appears to have very little restriction, but that is just a guess right now until it gets dynoed and remapped."

RB

 

[Guest]

The 993SS cam wasn't designed for hydraulic lifters - although I don't know if that makes any difference anyway. As I understand it, it was used in the 3.8 Cup cars (and perhaps in other applications like 964 Cup cars?). Also, a cam is a cam is a cam ! You can put most any 911 cam in any displacement 911 engine. It will change the character, just as displacement will mask the effects of a very peaky cam, for example, but it will run.

These are the technical specs:

MODEL DURATIONS .040" .050" lift C/L SETTING
964 I 246 238 .470" 113 1.26 mm
E 232 226 .430"

Super I 248 242 .490" 112 2.0 mm
Cup E 234 228 .455"

The table isn't very clear but in summary it shows that the durations are a little longer than the 964 grind cam and the lift is a little higher. It is about as "hot" a cam as you can run in a 3.2 in the two critical areas. First, valve/piston clearance and secondly, overlap in a common plenum intake engine. The theory is that it will make a little more power and also allow the engine to rev through to about 7,200rpm without the dramatic falloff in power that the SC/3.2 cam suffers after 5500rpm. So, from 5500rpm to 7000rpm it should actually make a lot more more power as the engine is able to "breath" or take in anough air to keep making power at these higher rev levels. That is the theory - yet to be proven on the dyno.

Is it designed for 3.2s? No, not really, but I don't know of any commonly available cam that is. The most common upgrade is the 964 cam but that is not a very dramatic step away from the SC/3.2 grind. The 993SS grind goes a step further. The gains are not huge as you can't use a cam like an "S" cam because of the two restrictions I noted above. Without paying for a cam to be developed, I think the 993SS cam will create the most power of any commercially available cam when used with the std Ps & Cs and intake/fuel system - I don't know of anything better anyway. I like the character of the cam so far - not peaky just a good flow of power that keeps building and building. I have only run the engine to 6500ish (due to running in) but it seems to work very well. I would guess that the midrange torque is a little down right now, but I think we can get it back with the mapping. Low restriction exhausts tend to lose midrange torque anyway, so this is not unexpected.

One engine builder basically told me I was being stupid using these cams and suggested I concentrate on the basics and get the most out of a standard engine with MOTEC mgmt to control fuel/spark. I just thought it was odd to put a "limiting" cam back in when I could put in something better and still at a later date add MOTEC if desired. Besides which, I am doing a full topend rebuild with race valve springs, Ti retainers, new rings, stretch type 993TT rod bolts and full SSI exhaust and new clutch and flywheel for, in round number, the same money as MOTEC purchase and install. That didn't add up to me.

Cheers,
Richard

 

[Guest]

ORIGINAL: MoC2S

Those specs look to be on the higher end for lift, with fairly moderate duration compared to the range quoted by Bruce Anderson - he recommends the 911S cam for 3.0 and 3.2s (less lift much longer duration) or the Jerry Woods GE40 which has duration 256 I 238 E, lift .470 I .440 E at 102 degrees Lobe Centre. I would do the maths to convert it into dead centre timings but .....

I think (but can't find confirmation) that hydraulic lifter cams have a different ramp profile - certainly all 993 engines have 993 part no cams including the RS ....

cheers, Maurice

I think you have missed the point - in fact both of them []

First, these are not 993 cams. They are, to be pedantic, a new billet 3.2 cam ground to 993SS specs in terms of lift, duration etc. So they are not in any way, form or respect designed for a 993 engine with hydraulic lifters. In this respect they are designed to work with a 3.2 and have been used in many, many 3.2s in the US. The only thing unique is that very few (if any) in the UK have used them in 3.2s - though one of my friends had them in his 964RS. I am not aware of the 993SS cam ever having been supplied for an hydraulic lifter engine. I believe it only ever went into 3.8 Cup engines. My chosen camgrinder has been in the business for many years and has supplied these cams for many 3.2s. I trust he knows what he is doing.

Secondly, you can't run 911S cams or GE40s in a std 3.2. The S cams fail in two respects. First the domed pistons in a 3.2 do not have the valve pockets that a 2.4S/2.7RS had so there is insufficient valve piston clearance (in fact negative clearance ie., they will hit big time). Secondly the common plenum induction cannot deal with the reversion pulses that an S cam creates, so the engine will never idle or run at under 3000rpm, more or less. The GE40s are similar in that they fail the valve to piston clearance test - but may run with common plenum induction, I don't know one way or the other. BTW, neither of these cams would work in a 964 or a 993 either, for the same reasons. To use these types of cams you need to use pistons with deep valve cuts and to use throttle bodies or carbs for the induction. On a 3.2 you would also have to go to twin plug ignition as the combustion chamber is effectively split with the deep pocket type pistons - which requires aftermarket engine management. You do the maths, this would have at least doubled the cost of my engine work.

You have correctly identified that the 993SS cams are on the high end for lift but not much longer for duration compared to an SC/3.2 cam for example. If you think about it, this is the only way to get more air in and out once realise you are restricted on duration and valve clearance. The only negative consequence is that the std valve springs becomes slightly marginal (though my friend ran std valve springs in his 964RS without issue). A heavy duty valve spring is better, but to be safe, I have gone for a race valve springs with the Ti retainers.

HTH
Richard

 

[Guest]

Expecting this any day now... its a trick lightweight aluminium pressure plate with a 240mm 930 sport disc.

 

[Guest]

Richard,don't mention clutches!!

Just had the car in for a routine clutch change and a new clutch,flywheel,rear main oil seal,shaft seal and various other sundries later the car is back!! Oh,and booked back in to replace two oil pipes in a couple of weeks.
the car drives great well so money well spent. the missus doesn't quite see it like that though![]

Cheers

Dave

 

[Guest]

You tell your wife what you spend on the car ?!?!?