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Rear Mount Turbo Progress??????

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Old 12-26-2005, 01:04 PM
  #121  
Ketchmi
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Here ya' go again...

I'm not a big fan of the TS setups "yet" as I have know of many more teething problems than the CS system has. That doesn't mean that they will not be fully sorted and glitchless in no time with all the effort being applied. As far as the CS system, it's pretty much sorted out and is making some serious horsepower reliably. You are speaking in theory, apply it and then you'll have something to compare. When I say boost is boost, the 89' on 10psi is such a blast to drive, has no downfalls and way too much power for full throttle playing in town. How much better could a turbo system be? If you had ever ridden in a CS 928 you would realize that boost is linear with rpm. If you are cruising around at 4krpm in a lower gear and stomp on it, as soon as you close the BOV, you are at considerable boost. Ain't no waitin' there... You expound the virtues of a turbo in optimum conditions for your setup. There are situations where a CS will be at an advantage which you either can't see or refuse to.

Even if you develop a TT kit that is cost comparitive to a fully sorted intercooled CS kit, your install costs will be easily double or triple that of a CS. Ask me how I know, I own a shop that does this all day long on various makes and models. Just because you can do it in "X" amount of time, you are used to it and quite experienced in what the requirements are. I have also helped many a self-installer make things right on their systems, nothing is plug and play in this arena.

You talk about people being mislead, your turbo preaching is doing just that. A CS 928 is a total blast to drive, I have only experienced one thrown belt in all of my time working on these, haven't hurt a single engine yet, get nothing but smiles anytime I take someone for a ride in one and have never once heard, even from the turbo guys, that they think a turbo could do it better. Anyone that hops into a properly boosted 928 will be all smiles regardless of what type of pressure creating device is used. Your talk of proper belt tensioning being required, with the systems in use today that's about every 6 months or so. About the same timeframe as when you should retension the rest of your belts...You talk a lot about things that you don't know firsthand and it's all detrimental toward the CS system. Experience one firsthand and you'll know what I'm talking about.

I don't care who told you that turbos were not a viable option for the 928's. Let it go. There are a lot more people that know they will work but it takes a considerable amount more design work to make it so. (tell me you don't know that firsthand!)
Old 12-27-2005, 07:22 PM
  #122  
Herr-Kuhn
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So, Dave are you saying the Centrifugal Supercharger is a better piece of hardware than the Turbo or Positive Displacement machine?

Do elaborate on when and under what conditions you think the CS can outperform the turbo. If you can prove this point with facts and data and not just talk I will listen. Until then it is just talk.

I've never misled anybody. Where were you earlier this year when I showed a 3-spd AT 928 with two tiny K-24s was quicker through a 1/4 mile than a 5-spd 928 running CS boost on the same motor? That car had the advantage of the 5-spd, the MPH was the same, but the Automatic turbo car was 0.3 seconds quicker. Same boost, same engine. In the "0-60 world" I'd say that is substantial. That car made the same HP as the CS car, but a lot more torque, especially down low with the small K-24 units. No telling how much quicker it would have been with a 5-spd. I've since sold that car.

Again, I present well documented reasons below that describe why the turbo is a superior choice for maximum performance (BTW, these were not made up by me, I just read them like any other normal person can go and do):

More efficient, uses otherwise wasted energy as source of power

Last longer, has fewer moving parts

Boost is a function of load, not RPM

Builds boost hard when you need it by dropping your right foot, properly sized can be made to supply low or no boost when out of vacuum under light to moderate throttle...this means less throttling, thus better street manners.

Self compensates manifold pressure at altitude, no pulley change is required when going up in altitude to keep set/design boost levels.

Quiet, in fact a very effective muffler

Allows you to run a nice "average" boost, no need to dial it up high at the top end to get a little/ medium boost in the middle...this means more real world power that can be put to use.

Never have you heard me say it is cheaper or easier to install. I just don't make those claims, but it is what everybody seems to want to point out to defend their point. So it will take you 2X as long to install, who cares? You have a nicer machine when done, would that not make it worth the effort? Most guys install themselves anyway, so in that example the cost does not come into play, just the time. Myself, I happen to enjoy seeing such a project come together.

Hey, I think Murf has done a heck of a job on his setups, they are clean, well thought out and perform very well as you have indicated. You won't see me cutting down anybody's work in terms of how it is applied, etc., though I do stand by the fact the turbo is a far superior compressor. That has been my point all along.

Dave, you make statements that make it sound like I have not put anything together yet. Simply not true. I'll leave you with some interesting turbocharged machines to think about:

Porsche 996 TT
Porsche 993 TT
Porsche 951
Porsche 917
Porsche 930
Audi R8
Saleen S7 Twin Turbo
Hennessey Viper...1000+ BHP
RUF Yellow Bird...This turbo car still makes regular appearances at top speed shootouts
Just about every diesel rig on the road today...does this define longevity or what?
Old 12-27-2005, 07:34 PM
  #123  
Jim_H
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To be fair, didn't your motor have quite a bit of work and $ put into it?

Originally Posted by Herr-Kuhn

I've never misled anybody. Where were you earlier this year when I showed a 3-spd AT 928 with two tiny K-24s was quicker through a 1/4 mile than a 5-spd 928 running CS boost on the same motor? That car had the advantage of the 5-spd, the MPH was the same, but the Automatic turbo car was 0.3 seconds quicker. Same boost, same engine. In the "0-60 world" I'd say that is substantial. That car made the same HP as the CS car, but a lot more torque, especially down low with the small K-24 units. No telling how much quicker it would have been with a 5-spd. I've since sold that car.

?
Old 12-27-2005, 07:49 PM
  #124  
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Yes, it did...but as I tell all people doing this...you should see the material properties for the cast pistons used in the 928 at elevated temps compared to a forging...it might scare a lot of people off. I believe the forged alloys are on the order of 5X stronger than the castings at the high temps. In terms of engine work, all it had was a set of JEs, 911 rings and the Nikasil bores. The engine needed to be gone through since the head gasket was leaking when I bought it. Every seal on the engine was shot, I replaced them all. I'm that way...if I do it I go all the way, not 1/2 way.

All total, I think I had about $13,000 in the car and all the goodies. Not too bad for a 350-375 HP 928. I had the surprise of having a bad trans on the first go...it did not take well to the 400+ ft-lbs that little engine pumped out. I sold the car for $9,000 to move onto "greener pastures". True I lost some money, but I got a great deal on my 88 S4. $10K with $30K in receipts from a very particular prior car nut. It all works out in the end. Besides, the car was pure and simple an R&D project car. I didn't expect to come out ahead on it. I have not heard back from the new owner, so I take it he is still enjoying the car.

I just feel fortunate to be able to tinker and modify a car like this. 15 years ago I could only dream about owning such a car.
Old 12-27-2005, 09:11 PM
  #125  
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This is arguing back and forth is getting retarded. At the end, all 3 type of boosting will make a 928 fast enough. The real world differences between the CS and the Turbo are so minor that it becomes almost insignificant. At the end it will all come down to total cost. This is the main reason why Chevy Cavaliers are sold by the $hit load every week. They are not the best by any strech of the imagination, but they are sure dirt cheap. It doesn't have to be really good, just good enough and people will buy it!
Old 12-27-2005, 09:11 PM
  #126  
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Boy John, it took you a while to come back with a response...

You need to read my posts a bit better. I never said that a CS was more efficient or a better way to boost, I just stated repeatedly that the differences were much less than you preach about.

The CS system works, works well and is not extremely expensive. It can be done by the average home mechanic without much trouble. The driveability is not a factor as it's basically stock until you close the BOV.

You have never ridden in a CS'd 928. You don't have a 32v TT built to compare to anything. Until then it's just talk...

The examples I gave are for higher horsepower levels and pretty much beyond the limits of traction. Once again, tell me how much better a turbo will be when at these levels? If it's spinning harder, it's not accelerating any faster.

I am not interested in what the manufacturers have done, what other people are saying or doing, or even examples of other peoples work on different cars. Let's keep this in perspective shall we? How about we limit it to THE 928, THE TWIN TURBO, THE CS SYSTEM, THE TS SYSTEM, THE REAR TURBO SYSTEM and once again THE 928!

BTW, just how many fewer moving parts are there in a turbo vs. a CS system? I think that the belt and tensioner are about it. How many more custom manufactured parts that must be replaced are there in a TT setup vs. a CS? ONCE AGAIN PLEASE LIMIT THIS ANSWER TO ONLY THE 928!

I have never questioned the longevity of the turbo system nor have I stated that I thought any type of boosting was superior. Who cares if the turbo is more efficient when you can't apply all the power anyway? Who cares if the turbo is more efficient when you are burning fuel at a horrific rate to produce mondo horsepower? Get yourself some experience in the passenger's side of a well done CS'd 32v at 10psi or above. It will leave you breathless and you will begin to understand what the hell I'm saying. The differences you are ranting about become very small at higher horsepower levels. Maybe you could actually listen to all the examples of CS owners when they talk about the driveability issues and traction problems they already have. Go ahead and make more power, more midrange torque and we'll sell you all the tires you will need. It doesn't mean you will be any faster...

I am not touting Tim's kits only, I use his brackets and pulleys but do the rest of it myself. We do custom installations for whatever the owner requires. Our customers don't install their own kits and we don't sell kits.

I think Tim's kits are filling a void in 928 performance. Andy's kits were doing the same and were well on the way to being fully developed if he would have/could have completed the task. I hope DR's TS kits function as well as everyone anticipates and he sells many. Mark R. seems to have disappeared again but he may be back with his single turbo kit and I wish him success also. I really want your system to be all you are saying is already is when it gets around to being completed. Just shut the hell up about how much better turbos are than sliced bread.

All these systems work, some better than others. Some do things that some people want, others do what others want. You will never convince everyone that wants a boosted 928 to purchase your kit, realize that and quit pushing everyone else down. Believe it or not, price is a large consideration for most 928 customers. Ease of installation is probably second. I believe your system doesn't rank anywhere near first in either of those two catagories.

I am rapidly tiring of this one-side-blind conversation. I don't hate turbos in fact we do some really nasty stuff for 951 owners every day. If and when you open your eyes and at least go for a ride in a properly prepped highly boosted 32v, I'll start listening again. I do believe that in a lower boost application such as OB's where you are not exceeding 400rwhp, the turbo has some benefits. THAT'S NOT WHAT I'VE BEEN TALKING ABOUT!

For your own good, work with the crowd...not against it. Some people will have an interest in your system. Hopefully you have not driven away too many of them. Share some of your experience with the rear turbo guys and see if it applies to some of their teething problems. You never know, I may be able to help you with some of the teething problems on your system...
Old 12-27-2005, 09:35 PM
  #127  
Herr-Kuhn
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Whatever...

http://www.hotrod.com/techarticles/42798/
Old 12-27-2005, 09:50 PM
  #128  
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John, you are totally missing Dave's point.

Lets not get into the "I can post an article to disprove your article" game, ok?

Fact remains there are over 30 very happy 928 owners with SC bolted on. That number will continue to grow. Hopefully there will also start to be a large number of turbo 928 owners running around in the next few years.
Depends on how much time you spend in the garage finishing your car vs trying to defend your views on the internet.
Finish your car, put a few thousand miles on it and prove your point. Many people (including me) are dying to see these results.
Old 12-27-2005, 11:20 PM
  #129  
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Wow, that's an intelligent response...

Read my post John, it pertains to 928's.
Old 12-28-2005, 01:25 AM
  #130  
Lance J
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Boost is boost. even if you have to spend crank power to get it or not. yes i think a turbo is alot better....(wait for it) to get yourself in trouble. i mean if i had to change a pulley to run higher boost then i'd make sure the fuel was map & timing was right. you could overboost your engine with a turbo so easy its not even funny. its so tempting to just crank it up. look at the saab guys they make one adjustment and max boost is upon them. lucky the car can handle it. i love turbos and i like superchargers. so lets twincharge a 928. lol put it like this if i'm in my shark (not yet boosted) and a vette spanks me and TONY chases him down and blows his doors off for me then i'm not gonna say that doesn't count as a win for the shark clan it wasn't a turbo. no matter whats strap on shark to make it faster if i see a shark spank another car i'm happy
Old 12-28-2005, 09:11 AM
  #131  
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Lance J writes:

"tempting"

"blows"

"strap on"

"spank"

NOW I'm developing an interest in this thread!



--Evil Patrick
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84 (for sale - cheap - make offer)
Old 12-28-2005, 10:06 AM
  #132  
Jim_H
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Different strokes...

Originally Posted by Evil Patrick
Lance J writes:


"strap on"



NOW I'm developing an interest in this thread!



--Evil Patrick
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Old 12-28-2005, 11:23 AM
  #133  
Herr-Kuhn
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Man this went south fast! Sounds like you guys have been watching too much Cinemax late night as of late.

My only point in all of this is there are significant differences in the way the car drives between the three main methods of forced induction. 10 psig turbo is very different than 10 psig Centirfugal as is 10 psig Positive Displacement. The way the car responds to throttle input is entirely different. One comes on hard off idle, the second comes off idle with no boost and builds it exponentially to a peak at the max RPM. The third comes off idle easy, then hits hard across the low-mid on up to the high end. So, no boost is not boost. You could figure a turbo V8 car would be at least 50-75 ft-lbs stronger through the mid range than a CS car. When you're under high loads, WOT at say, 4000 in 3rd gear you will see and feel the differences. To claim this would not make any difference is totally crazy. Hey, isn't this about building a fast(er) 928? If 0.5-1 second in a performance measure isn't important to you why did you modify the car in the first place?

Dave, I'm not quite sure whay you went on such a rant this time. I asked you to give me examples of when you though the CS could outperform the turbo (lb per lb) and all you came back with is attacks on the number of parts, length of install, more burned rubber, etc. You have yet to answer my question, I believe that is because you know the answer. I thought it was a simple question. You could respond by saying "at XXXX RPM under these conditions I believe it will outperform the turbo"...it was that simple. You never heard me claim there were fewer parts to change or that it was cheaper, just that boost is not boost as you claimed. Where have I misled? You need to back up your claims, not change the subject to get your way or stomp your foot like a two year old. Read the above article. I'll see if I can get a copy of the Aug 2003 Battle of the Boost article from the library this week. That will shed even more light and the test was done by a reputable publication.

What is this about overboosting easily with the turbo? Provided your wastegate lines are in working order and you have a set spring pressure and it is designed properly, there is no risk of overboost.

Now I must go, I have just three more pipes to modify and get over to the welder to complete the K-26 conversion on the 4.5 liter.
Old 12-28-2005, 02:04 PM
  #134  
Lance J
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i respect this forum and what it stands for so i wont take what you said personal. i'll finish my rear mount turbo setup and be happy that my 79 has boost. all i have to say is in your post b4 you quoted one guy 9k for a kit. man what should anyone pay 9k for a turbo when they could get a CS setup for half that. i put my kit together for $1500. your not helping the 928 turbo posters any with your overprice kit. if you wanna spend 9k on your personal kit thats fine and dandy. put for someone like me i'll be damn if i pay. all people want is a afforable way to boost.
Old 12-28-2005, 02:11 PM
  #135  
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I'll see if I can get a copy of the Aug 2003 Battle of the Boost article from the library this week.
I've got it (or had it). I'll take a look as well and see if I can drum it up.


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