911 engine/suspension

speednut567 · 12-26-2002, 02:56 PM

I need help choosing which 911 engine and suspension to used in a Porsche 356 replica I am considering to be custom built by Intermeccanica. I don’t have any experience with older Porsches and all I know I have learned by reading over the last two weeks. Any help would be appreciated

Background: This will be a daily driver (no track use) to be used by both my wife and I. My wife has some arthritis and we would like a tiptronic. She thinks she will also need PS and PB, but I have been told they are not necessary in a car this light (about 2,400 lbs.). PS and PB are still a question? We are looking
for a set up that will not just be fast, but will be easy to drive fast i.e great handling but also predictable handling. Previous cars were a 1999 Porsche 996 with tiptronic and 1995 BMW M3. These are the standard which we would like to come close to handling wise. (We also owned a 2000 M roadster that handled like a POS). Performance should be faster than a standard corvette (0-60 less than 5 sec. and top speed at least 170 mph.).

Issues: Engine- Based on power to weight calculations for corvette, I estimate I need a minimum 250 hp. I also want a lot of torque and a wide power band. From what I can tell the “best” engine would be a 993 3.6 engine with Varioram. But I have concerns that this may be more than I need with unnecessary cost , though I was told by someone that all rebuilt 911 engines will cost about the same ($15,000?).The extra cost could come from complicated engine install? From a simplicity standpoint (and possibly budget) I wonder if a 3.2 motronic with upgrades like twin ignition, chip, air flow improvements, performance exhaust would be better? Any thoughts about which approach is most practical? Will a tiptronic hook to the 3,2?Also looking for limited slip.

Suspension: It appears that the 993rear multilink suspension and front and rear coil over is a preferred suspension over the previous trailing arms and torsion bars. But I don’t know yet if this will fit the car (still have to talk to builder ). Can the old suspension be tuned to handle like I want with upgraded torsion bars, sway bars, etc.? I plan to use 17” Boxster wheels with 245 or 255/40 in back and 225/45 in front. I was told that standard mid 80’s Carrera brakes would be adequate for this light car. But I would like ABS and assume that I would need a later set-up for that?

A big concern of ours is the so called “tail happy” nature of the older Porsches. I read that this is not an issue with a properly set up chassis, as long as you stay away from the cars handling limit (then it can bite without warning). If this is the case I don’t have a problem, as we would not be pushing the limit (assuming it has high limits), but is this an issue in emergency handling (i.e. swerving to miss a dog in the road)?

Based on what I am trying to accomplish, what is the most practical from an initial and ongoing cost, reliability, maintenance standpoint? Cost is an issue, if too high we will buy a new M3, but sure would like this unique Porsche. Thanks

Steve

john_colasante · 12-26-2002, 03:32 PM

You're talking about alot of very exotic mods that will take extensive fabrication to accomplish in a 356 kitcar. For example a Tiptronic is heavily integrated with the cars chassis and computer, so it will require mods that will break your budget. Also fitting a 993 rear suspension will again take extensive fabrication. I would expect you'll be into $100K with only a few of the mods you're considering. My guess is that you're going to have to drop all of the exotic stuff (Tiptronic, ABS, 993 syspension) and settle for less extensive mods if you need to fit into a budget less than a new M3.

speednut567 · 12-26-2002, 04:07 PM

Thanks John:
This particular car is already modified to fit a 911 engine and transmission and mid 80's 911 suspension within budget. It sounds like you are saying that the tiptronic/abs/993 suspension might require too much additional mods. I can understand the 993 suspension problem, but did not realize the tiptronic was such a problem. Would it make a difference to use a post 89 3.6 with the tip vs. trying to make work with a 3.2?

Steve

john_colasante · 12-26-2002, 04:16 PM

I don't know anything about the kit in question but if it is setup to work with a 915 gearbox then fitting a Tiptronic will require the chassis to be modified because the Tip will be a longer unit. The 993 LSD suspension is also significantly different from a mid-80's 911 rear suspension as far as the mount points are concerned. As for ABS the whole wheel carrier and hubs will need to be modified. Plus all of the electronics for Tip and/or ABS will need to be grafted in - not an easy task. Have you discussed these ideas with the builder? It seems he will be able to directly address the costs and feasibility of these ideas.

john walker's workshop · 12-26-2002, 04:34 PM

the TIP pretty much rules out that project. a sporto would be a lot easier, although still a minor challenge.

speednut567 · 12-26-2002, 04:38 PM

I did indeed discuss my "wish list" for 993 suspension and tip/abs with builder. The reponse was pretty much as you have indicated -that is- too costly. I did not have time to get into specifics as to why, and what partial things we may be able to work in because I really did not know ( and still don't) what would be reasonable to expect and what would not be reasonable from a cost/benefit standpoint. The builder is closed this week and I am trying to educate myself as much a possible before re-starting the building discussion.
At least you are giving me information consistent with the builder.
I think the 993 suspension is probably definitely out. Does this mean I am stuck with significantly less handling even with upgraded torsion bars/sway bars, etc?
If the tip can be engineered to fit without problem, any way to minimize the electronic mapping issue? I could probably do without ABS.
thanks.

Steve

speednut567 · 12-26-2002, 04:51 PM

Quote:

Originally posted by john walker's workshop
the TIP pretty much rules out that project. a sporto would be a lot easier, although still a minor challenge.

Is a sportmatic fully auto or a clutchless shifter?Maybe ok if fully auto.

Can someone help me understand why the tip is such a big deal. I am not wanting the steering wheel switches, just the floor shifter box. Since the post 89 3.6 was available with tip as option I thought it should be a matter of just hooking up the wires.

Thanks.

john walker's workshop · 12-26-2002, 05:14 PM

the sporto has no clutch pedal, but has to be hand shifted. it takes more effort to crank the steering wheel than to do the shifting. how bad is the arthritis?

john_colasante · 12-26-2002, 05:15 PM

The pre-993 suspension is considered tricky. But if you can minimize these qualities by tuning it. Alignment, spring rates, shocks, antiroll bars, bushings - they all play a role. In general you want to stiffen it up and lower it. Remember the 911 was one of the most successful sports racing cars for three decades with this suspension design.

I have not worked the Tiptronic transmission but from what I understand the electronics are half of what makes it work. It's tied into the gas pedal, the shifter, the engine ECU, the steering wheel paddles and a host of sensors. I do not think it will work at all unless most if not every input is working correctly. Now maybe there's a hotrodder out there who can provide the inputs but it's not a popular thing to hotrod. Unless your guy is a Tiptronic expert and has reverse engineered the electronics he is going to pass on it.

My guess as to what will be doable for the 356 will be limited to well know suspension and/or engine mods or a 3.6 with the stock computer wired in. It is popular to put thiose engines in early cars.

speednut567 · 12-26-2002, 05:26 PM

Quote:

Originally posted by john walker's workshop
the sporto has no clutch pedal, but has to be hand shifted. it takes more effort to crank the steering wheel than to do the shifting. how bad is the arthritis?

The problem would be where my periodic episodes of laziness flares up . Could interfere with coffee drinking.

speednut567 · 12-26-2002, 06:00 PM

Quote:

Originally posted by john_colasante
The pre-993 suspension is considered tricky. But if you can minimize these qualities by tuning it. Alignment, spring rates, shocks, antiroll bars, bushings - they all play a role. In general you want to stiffen it up and lower it. Remember the 911 was one of the most successful sports racing cars for three decades with this suspension design.

I have not worked the Tiptronic transmission but from what I understand the electronics are half of what makes it work. It's tied into the gas pedal, the shifter, the engine ECU, the steering wheel paddles and a host of sensors. I do not think it will work at all unless most if not every input is working correctly. Now maybe there's a hotrodder out there who can provide the inputs but it's not a popular thing to hotrod. Unless your guy is a Tiptronic expert and has reverse engineered the electronics he is going to pass on it.

My guess as to what will be doable for the 356 will be limited to well know suspension and/or engine mods or a 3.6 with the stock computer wired in. It is popular to put thiose engines in early cars.

The builder was not that familiar with tips and from what you are saying it looks like we need to get up with an expert tip person to discuss cost. Bummer to here it is not an easy mod.Could be a deal breaker.

The builder does seem very knowledgeable about the pre 664/993 suspension set up and I believe will complete the right tuning. Anybody drive an m roadster that can give a handling comparison? I hope the porsche set-up is better.

Thanks. Your comments help me understand what to expect.

steve

widebody911 · widebody911's Garage

If daily driving comfort are your primary concerns, get the M3 and kibosh the speedster idea. Sure, you could spend al kinds of money to make a fiberglass replica run and fell sorta kinda like a 993 or an M3; but give me enough time and money and I can do the same to your John Deere riding mower.

Speedsters (and replicas) are best enjoyed as spartan fun good-around cars, not serious daily driver cush-mobiles.

speednut567 · 12-26-2002, 07:07 PM

Quote:

Originally posted by widebody911
If daily driving comfort are your primary concerns, get the M3 and kibosh the speedster idea. Sure, you could spend al kinds of money to make a fiberglass replica run and fell sorta kinda like a 993 or an M3; but give me enough time and money and I can do the same to your John Deere riding mower.

Speedsters (and replicas) are best enjoyed as spartan fun good-around cars, not serious daily driver cush-mobiles.

I agree with you that the replica is not going to have the comfort and technology of a modern car like stability control, power everything, etc. The M3 is a great car and fun to drive but IMO it is as boring to look at as a honda accord. We really love the 356 look and hope to be able to put together a reasonably comfortable daily driver with performance close to the M3 (at least faster , maybe not as good handling-but safe handling ) .

The Intermeccanica replica is not your tipacle speedster replica. It is actually a convertible D and comes with roll-up windows, air conditioning, leather heated seats, and with the right Porsche running gear we will have a car that outperforms just about everything on the street-all for less than the cost of Boxster.

My wife is already set on this car- so I need to make it work!She saw a 356 in a movie and she is from the south and she carrys the reccessive gene for bootlegging liquer and wants a FAST 356.She would drive NASCAR if they drove Porsches.

Don Plumley · Don Plumley's Garage

Off the wall reply - A while ago in Panorama there was an article about a 356 that was built on an SC/911 chassis (I think). Anyway, maybe you could consider finding a 993, cut off the body (gasp) and fit a 356 shell on that? Yes, I know it needs to be wider and longer, but that was the basics behind the car in Pano. From a short distance you would not know it was not a 356, but upon closer inspection it was wider. This would at least solve your tip/abs/power steering needs.

widebody911 · widebody911's Garage

Quote:

Originally posted by speednut567
...and with the right Porsche running gear we will have a car that outperforms just about everything on the street-all for less than the cost of Boxster.

You'll to redefine "outperforms everything on the street" and "less than the cost of a Boxster"

My wife is already set on this car- so I need to make it work!She saw a 356 in a movie and she is from the south and she carrys the
There's the root of your problem... Call me a pessimist, but I pragmatically would find it cheaper to change the customer and project rather than try to fight the scope creep.

You might be better off starting with a 993, cutting the body off, and bonding the speedster body on what's left.

widebody911 · widebody911's Garage

I went back and re-read the first message, and have come to the conclusion we've been trollled.

speednut567 · 12-26-2002, 08:04 PM

Quote:

Originally posted by widebody911
I went back and re-read the first message, and have come to the conclusion we've been trollled.

Not sure what you mean by the term "trolled". My wife and I are
looking for helpful input on what Porsche engine and suspension will most practically achieve the performance we are looking for. I too am pragamatic, but once my wife is fixated on something I am doomed. She is as tenacious as a dog with a bone. (God help me).

The idea of chopping off a 993 and putting a 356 body on it is literally the ideal car but likely more expense and impractical than putting 993 components in a proven 356 replica frame. The fact is that a 250 +hp porsche engine can be put in this 2400 lb car and outperform anything short of a Porsche turbo, corvette L?, or viper. The cost to do this (with mid 80s 911 suspension is less than the cost of a new Boxster. This is already a fixed identified cost. We are asking for help/ideas on if it is feasible and how we can upgrade to 993 /ABS/Tiptronic.

john walker's workshop · 12-27-2002, 07:25 AM

those kit cars were not designed to use those components. it would be back to the drawing board for a total redesign just for you. the builder isn't going to do that.

ben parrish · 12-27-2002, 08:28 AM

Speednut,
I owned an Intermeccanica factory built speedster for over ten years and I can attest to the quality of this vehicle and it's Canadian owners. I must however caution you in your plans to have the above mentioned mods made with the desire of making a "better than anything at a lower cost" daily driver. I suggest you find a 356 and have your wife drive it for a while before deciding that this is the way you want to go. The fact is that a repli-car is just that; a replica of it's "real" counterpart. GREAT REPLICA, thats it, no matter what the mods and how much you can spend. Look at the post of the 912 speedster; might be an option at a lower cost and equal outcome. Good luck.

masraum · 12-27-2002, 08:43 AM

From the sound of things you could build the car you are talking about for tons of money, bucket at a time. I would think the cheapest way to accomplish the wish list, 356 look, PS, PB, 993 3.6, modern suspension, all fast an easy enough to drive for someone with arthritis, capable of 170 (356 speedster?), I would say your best bet would be to buy a 993 or 996 and then spend a small fortune getting someone to custom make a 356 body to go on the tub instead of a large fortune trying to get all of the parts mounted and working on a chassis they weren't designed for. It would be easier to start with everything working and just cut the body off and start with a rolling functioning chassis with all of the electrics still intact.

Sound like you are asking for the impossible unless you have a nearly unlimited budget.