View Poll Results: Adding BAE Turbo kit to my 911
I PM'd telling you it's dumb. All my work is done by a dealer because I'm afraid to change my oil.
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Turbo kit being added to '77 911s
07-10-2006, 12:26 AM
#1
Burning Brakes
Thread Starter
Turbo kit being added to '77 911s
I'm planning to add a BAE turbo kit to my 1977 911s and anothre Rennlister suggested I post a new thread on this forum about this project. BAE built these kits for a while in the 1980's and the person who sold me this seemed competent and sincere in his promise that its condition is good. He is an active participant in the Pelican Parts forum, so let me know if you want to reach him.
I've done some research and found out that my "7R" crankcase is the strongest 2.7 crankcase built, and that it is actually aluminum instead of magnesium. My engine was also rebuilt less than 20,000 miles ago, receiving all the recommended upgrades and making it as strong as any 3.0. My transmission was also refreshed and a Kevlar clutch was added.
Before installing kit, however, I need to re-curve my distributor to limit the amound of centrifugal and vacuum advance to a total of 20 degrees. I'm thinking of buying an MSD system for this purpose and would like to hear any advice about this approach.
If you send me your email address I will send you a copy of the entire installation manual.
I've done some research and found out that my "7R" crankcase is the strongest 2.7 crankcase built, and that it is actually aluminum instead of magnesium. My engine was also rebuilt less than 20,000 miles ago, receiving all the recommended upgrades and making it as strong as any 3.0. My transmission was also refreshed and a Kevlar clutch was added.
Before installing kit, however, I need to re-curve my distributor to limit the amound of centrifugal and vacuum advance to a total of 20 degrees. I'm thinking of buying an MSD system for this purpose and would like to hear any advice about this approach.
If you send me your email address I will send you a copy of the entire installation manual.
07-10-2006, 03:41 AM
#3
Burning Brakes
Thread Starter
I've heard 5-6 lbs of boost can be acheived without adding another injector and fuel controller. I'm going to start with the least boost possible, then add a little more in increments.
There are no chips for my old CIS system since it has no computer. I've added SSI exhaust and a K&N filter so far, but hope to push closer to 300 hp as long as I can keep it reliable.
Right now my oil almost never hits 200' F, to my temp gauge is the first think I'm going to watch. Once my distributor is recurved, the turbo just bolts on like a muffler replacement, so if I don't want to keep it I can easily remove it.
There are no chips for my old CIS system since it has no computer. I've added SSI exhaust and a K&N filter so far, but hope to push closer to 300 hp as long as I can keep it reliable.
Right now my oil almost never hits 200' F, to my temp gauge is the first think I'm going to watch. Once my distributor is recurved, the turbo just bolts on like a muffler replacement, so if I don't want to keep it I can easily remove it.
07-10-2006, 03:49 AM
#4
RL Technical Advisor
Chris:
If I may say,........
I've only seen 1 7R aluminum case in my 33+ years of Porsche street & race cars (and that was a KMW-Porsche) so I'd confirm your 7R case is aluminum since the mag cased versions are a poor candidate for turbocharging.
If you stick to something around 225-250 HP, it should be reasonably reliable as long as the case has ALL the necessary prep work and you control your oil temps between 185 and 200 deg F.
If I may say,........
I've only seen 1 7R aluminum case in my 33+ years of Porsche street & race cars (and that was a KMW-Porsche) so I'd confirm your 7R case is aluminum since the mag cased versions are a poor candidate for turbocharging.
If you stick to something around 225-250 HP, it should be reasonably reliable as long as the case has ALL the necessary prep work and you control your oil temps between 185 and 200 deg F.
07-10-2006, 12:05 PM
#6
Porsche thought it worth the effort to use a different block in the early street turbos. They were rated at 260 din hp (about 235 sae) using the 3.0L core. I think the kit may be more problematic than not, especially since an increase in power also needs an increas in braking ability and potentially larger rear wheels and flares.... If you only want 220-230 hp, I would think a nicely prepped 3.2l would be a more reliable choice.
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07-10-2006, 10:30 PM
#8
Burning Brakes
Thread Starter
I'll try out the turbocharger kit but am keeping it very conservative.
Some say too much power ruins the feel of the 911 and that I should just put a supercharger on my 928 instead. My current opinion is that I will probably just need to use my right foot more gently.
Of course none of this will happen until I re-curve the distributor. I used to re-curve my old GTO distributor with looser springs on the centrifugal weights. Can anyone recommend a kit for doing the same for my 911?
Some say too much power ruins the feel of the 911 and that I should just put a supercharger on my 928 instead. My current opinion is that I will probably just need to use my right foot more gently.
Of course none of this will happen until I re-curve the distributor. I used to re-curve my old GTO distributor with looser springs on the centrifugal weights. Can anyone recommend a kit for doing the same for my 911?
07-10-2006, 11:43 PM
#9
Race Car
Since you're asking for opinions...
...let me play Devil's Advocate for a minute.
If it is a magnesium case motor, especially, it probably isn't wise to throw this kind of money at it. And by 'this kind of money,' I mean both the initial cost of the used kit, and then all the as-yet-unforseen costs that will follow an initial dyno run that shows you've cut into your car's low-RPM grunt and driveability for the sake of a spike toward a peak output of something like 200-215 crank horsepower. In trying to get closer to the 300 hp number, I think you're going to see your expenses rise in a way that just means more and more bucks for a frankly still-modest bang. I mean, what's a worthwhile figure to put on creating a laggy powerplant that produces less real-world useable power than a Honda Odyssey?
Everyone goes into turbocharging with an 'I'm not going to be like those other guys -- I'm going to be as conservative as a grandmother' attitude. Everybody does. And pretty much everybody ends up waist-deep in another rebuild, some time later, because, well, let's face it: none of us, deep down, is a grandmother. Once you get spanked at a light by a minivan, you're going to turn that dial up. It's a heat-of-battle thing, and I don't think I've ever met a guy (myself included) who was able to resist.
And if you accept that sooner or later you're going to want more, then the smart way to do this would be to try to imagine what your future self's hindsight would be. 'Should I have started out turbocharging such a small motor?' 'Is anyone giving out points, anywhere, for ambitious use of small displacement?'
In the real world, you push the pedal and you want to go fast, right? I believe anyone building a performance car should acknowledge this basic truth, and work from there.
And that brings me to my final thought. I think you need to ask the age-old question: 'what am I building this car for?' An aftermarket turbo system designed in the late seventies or early eighties is probably going to have pretty terrible power delivery characteristics for most of the things we love 911s for. It's not going to be ideal for use in an autocross or DE; lower-hp cars with more linear power delivery will eat you for lunch. It won't be a good car for carving through twisty roads, since you'll be combining one of the twitchier, tail-happy 911 designs with the kind of lag that will aggravate most of an unflared 911's shortcomings. It won't even be much of a stoplight-to-stoplight racer, since the guy in the next lane isn't going to have to wait a few precious heartbeats while a not-so-high-tech turbo spools up.
As you're describing it, the car will really only be good for two things. One is just being able to experience the yin and yang of lag and boost. You'll be able to look over at your passenger and say 'watch what happens once the turbo spools up,' and feel the kick of the car coming on boost. Right after that, you'll have to explain that the neck snap would be a heck of a lot more impressive if you weren't so conservative about your boost level.
The other thing it will be good for is posting a scan of a dyno sheet on the internet. The problem is, it probably won't be the first dyno run that you post. It will probably be the one that came after you got the kinks out of the kinks, after adding the higher-tech goodies that led to the intercooler and the other items on the list of things you didn't include in the original build sheet for your 'this is the economically sensible way to do it' motor. By then, you'll have spent a lot of money, and the car still won't be very driveable, really, although it might be 'dyno-sheet-postable.'
Okay, that's my Devil's Advocate position. I don't offer it because I think you shouldn't modify your car. (I modified the heck out of mine.) But I would say that you should think of an end point to this journey that makes practical sense and work out a realistic path to get there. I'll offer the full disclosure that I'm not a turbo expert at all, and that I don't know a thing about your particular kit. But my guess would be that using an aftermarket turbo kit designed 20 years ago on a small, more-problematic-than-most Porsche motor might not be the best or the cheapest way to build a fast 911. As others in this thread have mentioned, there are larger-displacement 911 motors that might make for a much more affordable solution, if you swapped one in and sold your rebuilt unit.
And then there's always the truly smart economic path, which is to sell the 911 you've got, and use the money to buy the 911 you want. For some reason, hardly any of us (myself included) ever does this dollars-smart option. We're all too hooked on the idea of transforming the car we've already got in our garage.
So, there's my advice -- which I, of course, haven't actually followed. Oh, and it took more than a minute, too.
...let me play Devil's Advocate for a minute.
If it is a magnesium case motor, especially, it probably isn't wise to throw this kind of money at it. And by 'this kind of money,' I mean both the initial cost of the used kit, and then all the as-yet-unforseen costs that will follow an initial dyno run that shows you've cut into your car's low-RPM grunt and driveability for the sake of a spike toward a peak output of something like 200-215 crank horsepower. In trying to get closer to the 300 hp number, I think you're going to see your expenses rise in a way that just means more and more bucks for a frankly still-modest bang. I mean, what's a worthwhile figure to put on creating a laggy powerplant that produces less real-world useable power than a Honda Odyssey?
Everyone goes into turbocharging with an 'I'm not going to be like those other guys -- I'm going to be as conservative as a grandmother' attitude. Everybody does. And pretty much everybody ends up waist-deep in another rebuild, some time later, because, well, let's face it: none of us, deep down, is a grandmother. Once you get spanked at a light by a minivan, you're going to turn that dial up. It's a heat-of-battle thing, and I don't think I've ever met a guy (myself included) who was able to resist.
And if you accept that sooner or later you're going to want more, then the smart way to do this would be to try to imagine what your future self's hindsight would be. 'Should I have started out turbocharging such a small motor?' 'Is anyone giving out points, anywhere, for ambitious use of small displacement?'
In the real world, you push the pedal and you want to go fast, right? I believe anyone building a performance car should acknowledge this basic truth, and work from there.
And that brings me to my final thought. I think you need to ask the age-old question: 'what am I building this car for?' An aftermarket turbo system designed in the late seventies or early eighties is probably going to have pretty terrible power delivery characteristics for most of the things we love 911s for. It's not going to be ideal for use in an autocross or DE; lower-hp cars with more linear power delivery will eat you for lunch. It won't be a good car for carving through twisty roads, since you'll be combining one of the twitchier, tail-happy 911 designs with the kind of lag that will aggravate most of an unflared 911's shortcomings. It won't even be much of a stoplight-to-stoplight racer, since the guy in the next lane isn't going to have to wait a few precious heartbeats while a not-so-high-tech turbo spools up.
As you're describing it, the car will really only be good for two things. One is just being able to experience the yin and yang of lag and boost. You'll be able to look over at your passenger and say 'watch what happens once the turbo spools up,' and feel the kick of the car coming on boost. Right after that, you'll have to explain that the neck snap would be a heck of a lot more impressive if you weren't so conservative about your boost level.
The other thing it will be good for is posting a scan of a dyno sheet on the internet. The problem is, it probably won't be the first dyno run that you post. It will probably be the one that came after you got the kinks out of the kinks, after adding the higher-tech goodies that led to the intercooler and the other items on the list of things you didn't include in the original build sheet for your 'this is the economically sensible way to do it' motor. By then, you'll have spent a lot of money, and the car still won't be very driveable, really, although it might be 'dyno-sheet-postable.'
Okay, that's my Devil's Advocate position. I don't offer it because I think you shouldn't modify your car. (I modified the heck out of mine.) But I would say that you should think of an end point to this journey that makes practical sense and work out a realistic path to get there. I'll offer the full disclosure that I'm not a turbo expert at all, and that I don't know a thing about your particular kit. But my guess would be that using an aftermarket turbo kit designed 20 years ago on a small, more-problematic-than-most Porsche motor might not be the best or the cheapest way to build a fast 911. As others in this thread have mentioned, there are larger-displacement 911 motors that might make for a much more affordable solution, if you swapped one in and sold your rebuilt unit.
And then there's always the truly smart economic path, which is to sell the 911 you've got, and use the money to buy the 911 you want. For some reason, hardly any of us (myself included) ever does this dollars-smart option. We're all too hooked on the idea of transforming the car we've already got in our garage.
So, there's my advice -- which I, of course, haven't actually followed. Oh, and it took more than a minute, too.
07-11-2006, 12:24 AM
#10
Burning Brakes
Thread Starter
You have a nice car, Jack, and thanks for the comments. I cannot disagree with most of your points, except that it may be cheaper to change engines.
I will consider buying a new engine if this one breaks. Of course any new engine I select will have more displacement than this 2.7. If there were a market for selling my 2.7 I would consider that, too, but there is no demand for it so I will make use of it. Bird in hand, and all of that.
Low-end torque should not diminish much, if any, with the addition of a turbo, but I'm going to have to be careful with the throttle in high-RPM twisties. Life and limb are the biggest risks here. Who knows, after the first week of boost I may decide to yank the kit off and pass it along to the next enthusiast.
I will consider buying a new engine if this one breaks. Of course any new engine I select will have more displacement than this 2.7. If there were a market for selling my 2.7 I would consider that, too, but there is no demand for it so I will make use of it. Bird in hand, and all of that.
Low-end torque should not diminish much, if any, with the addition of a turbo, but I'm going to have to be careful with the throttle in high-RPM twisties. Life and limb are the biggest risks here. Who knows, after the first week of boost I may decide to yank the kit off and pass it along to the next enthusiast.
07-11-2006, 05:48 PM
#11
Poseur
Rennlist Member
Rennlist Member
We did this to my 3.0 litre 1981 SC many years ago and it was the best running car I ever had (until my latest P-car). We ran a conservative boost on it and it produced about 270hp and with the facotry 915 tranny would pull all the way to redline in 5th gear which was 162 mph. When you start to mess with an engine like that you need to get serious about other things too, like aerodynamics and brakes. I had the distributor curve relined and ultimately shimmed out the Ps&Cs to keep the CR reasonable for the boost. Bring lots of money when you go do this. There is no inexpensive way to get HP.
07-11-2006, 06:54 PM
#12
Burning Brakes
Thread Starter
Roger that, and thanks Dan. Please explain what you mean by "shimmed out the Ps&Cs" to lower compression ratio. I only have a CR of 8.5/1, but I'm curious about what you meant.
The topic of hp apparently touches a nerve in this forum, unlike the 928 forum where everyone loves to hear when another member adds boost to their "Shark."
I am in touch with about a dozen others who are using the same kit I have. The ones that have trouble usually confess to turning up the boost beyond their fuel managment system's point of eficacy.
The topic of hp apparently touches a nerve in this forum, unlike the 928 forum where everyone loves to hear when another member adds boost to their "Shark."
I am in touch with about a dozen others who are using the same kit I have. The ones that have trouble usually confess to turning up the boost beyond their fuel managment system's point of eficacy.
Last edited by LaughaC; 07-11-2006 at 11:29 PM.
07-12-2006, 01:20 AM
#13
2nd Gear
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I think I would take Jack Olsen's devil's advocate comments to heart. I've got a '74 911 with a turbo that was added by a Porsche dealer in the early 80s. The car has 74K on it and has been rebuilt twice. The first time, pistons and cylinders were worn out. The second time was a cam chain tensioner. I now have a 7R case in the back of my shop and I guess I'm waiting for the axe to fall again.
The car runs great and the performance when the turbo comes in is really impressive. But it does all happen at once and you really have to think ahead and be ready for the big surge. The car runs hot when the ambient air is over 80F. This car is mostly a mountain state weekend cruiser and has not been on the track. I'd give up the the extra power to have a car that was reliable with predictable acceleration throughout the power band.
When this engine goes, the replacement will be the 7R (non-turbo). (I think it would go down a winding road faster and safer than the turbo)
The car runs great and the performance when the turbo comes in is really impressive. But it does all happen at once and you really have to think ahead and be ready for the big surge. The car runs hot when the ambient air is over 80F. This car is mostly a mountain state weekend cruiser and has not been on the track. I'd give up the the extra power to have a car that was reliable with predictable acceleration throughout the power band.
When this engine goes, the replacement will be the 7R (non-turbo). (I think it would go down a winding road faster and safer than the turbo)
07-12-2006, 07:40 AM
#14
Burning Brakes
Thread Starter
Understood.
Twisties + turbo = spin
Lean fuel or pinging = boom
Thanks for the advice and let me know if you want to make an offer on my rebuilt 7r 2.7 before I boost it.
I've heard monitoring exhaust gas temp is the most accurate way to gauge fuel ratio and aviod ping. A good friend did this successfully on his turbo Buick when he dialed it in to run 11 second quarter mile passes. Does anyone here have experience doing this on a pre-computer 911?
Twisties + turbo = spin
Lean fuel or pinging = boom
Thanks for the advice and let me know if you want to make an offer on my rebuilt 7r 2.7 before I boost it.
I've heard monitoring exhaust gas temp is the most accurate way to gauge fuel ratio and aviod ping. A good friend did this successfully on his turbo Buick when he dialed it in to run 11 second quarter mile passes. Does anyone here have experience doing this on a pre-computer 911?
Last edited by LaughaC; 07-12-2006 at 10:08 AM.
07-12-2006, 02:16 PM
#15
I haven't heard any comments about the Timecerted head studs that are in the case. I think that would be a basic necessity, especially with +5lbs boost trying to lift the heads off.
Otherwise, it's one way to increase torque and HP. Don't fool with the boost pressure without further safeguards.
Sherwood
Otherwise, it's one way to increase torque and HP. Don't fool with the boost pressure without further safeguards.
Sherwood