Erik
If you look you will see that I have given each of the builders credit where credit is due, ALL of them. You don't find post here from me stating that Tim's product isn't worth buying, will be high maintainence, etc., and I sure as heck think David Roberts' product is a very nice piece of work. Kudos to Andy Keel AND Dave Roberts for plowing the way on that system, because it is an aesthetic work of art. Kudos to Tim Murphy for making an affordabe and good performing system too. But please tell your friends to not insult me by saying my system is unproven or can't perform to the levels of a CS car on the same pressure levels. Those statements are simply not true.
Erik, you are free to come to my place anytime for a ride in my car. I've ridden in V8 cars (5.0 liter big head Mustangs) with centrifugals that make 400+ RWHP and I've obviously ridden in turbo cars at the same level of power production. It's a totally different experience.
You misunderstood the word "the", it was not meant to make you think there is only one way to turbo the 928 (i.e. my way). Perhaps if I had said
"THE" then it woudl have been different. You see this is the problem with the internet, as you can't read my facial expression nor can I read yours.
Did I ever say any other system didn't have good road manners Erik? Please don't twist around everything I say to be a negative towards you or your friends and/or their products.
The fact that another system used a higher pressure ratio, less efficient compressor and burned more fuel to make the same power is conducive to making more heat. You have to think big picture here Erik, not just is what is happening right off the cylinder heads. As I said, yes the turbo car does likely see more heat on the valves, but it is no the order of magnitude you would like it to be.
Has anybody bothered to look at the compressor maps on all other boosting systems before making claims on underhood heat? Any comparison made has to be done with several variables fixed. You can't compare one system on X power to the other on Y power, it doesn't work that way. As I recall the Vortechs run about 70-72%, which is good, but not as high as the turbos, therefore they are making more heat into the charge at the same pressure ratio as the turbos do.
I'm unclear on why a bunch of guys who are all supercharger are so interested in making negative statements on twin turbo pricing. Where did I ever say Tim and Todd could not build a turbo car? I will say I do find it very interesting that as soon as I release data on my product that you continue to harp about how this was studied in the mid 90s and dismissed because it "wasn't worth it". Porsche doesn't agree nor do the guys that won LeMans in the Garrett ball bearing twin turbo powered Audi R8.
Only I know my costs, labor time and what profit margin I want to make. And only I know what is involved with the installation. There is nobody else who knows this information and anyway Erik, why does it matter to you to begin with, you already said you didn't want one, right?
So don't buy it, but please extend me the courtesy of actually releasing the pricing before you and your friends jump all over me about it. That is "reactionary" and exactly what I was referring to. People who don't want to cut the body won't buy the product, but either way is has no impact on you whatsoever, so why even make the statement? You and your friends reacted to my results Erik, it is so obvious. I can't even put an ad on E-bay without you and your posse attacking me on it on some stupid internet forum. Grow up for Pete's sake, everybody knows your game here Erik. No joke, I often wonder if you guys are on a sales commission plan.
The comparison on the 4.2 Audi and the 2.7T is
useless because the 2.7T is 250 HP and the 4.2 is 300 HP in the same basic chassis. The 2.7has virtually zero lag (I know my mother has one and I've spent some time in it). The NA 4.2 simply has 50 more HP, more torque, and is faster, forget mention that it has bigger wheels, suspension, brakes, creature comforts. It's just a nicer car period. The 2.7 can easily be built to 400 HP to make the 4.2 feel doggy. Again, big picture, and as always, apples to apples.
Mysterious Michagan Screw Pump Man:
My system
will not be offered at 2X what a supercharger is selling for. What do you mean "How can this be true?" What kind of leading statement is that anyway? This can be true and is fact because I designed it, I know the costs, and I will set the price. The first two of those three are done, the third is not, so it is therefore complete speculation for anybody to make statement on something they can't possibly have any information on. Do you know what my intercoolers cost, or the water pump, or the head flanges? No, because nobody knows or has the rights to even buy those parts since my company owns the designs. About the only piece anybody could possibly look up is the turbos and as a small business owner I pay a price lower than retail, so it's really impossible for anybody to know
my numbers there too. Your statement about "bankrupting myself"??? Where in creation did that come from? I'll assure you there is less money in my car than in your's and many others out there too. It's hard work and took a lot of time and effort in an environment of being continually attacked, but it is
far from bankrupting me. I'm glad everybody knows my financial status in life now too. Thanks. Is this a satisfactory answer for you regarding the "price"?
You completely misunderstood the point I was making on over-revving. I was not even referencing overrevving the SC to get the desired boost pressure, but rather referring to if you over-rev the engine and listing what happens if you do so with each of the three systems. The TS and Turbo will not overboost, whereas a CS will because the shaft speed of the compressor went past its designed setting (for that application) and therefore made higher boost. Spin it to 7K and watch the boost overshoot what you designed it for. I'm sorry if that was unclear, but I think you totally misunderstood what I was saying there.
The reason Top Fuel dragsters don't run turbos is because they were banned a long time ago after being penalized and having to add hundreds of lbs. becasue they were out ahead of the blower cars. Besides this point, I never viewed the 928 as a drag race type of car, that is never what it was designed to be. To me it's about mid range and top end in this car. You guys keep talking lag, lag, lag. My system runs high-medium sized ball bearing turbochargers that come on gangbusters (i.e. full boost) by about 3K and in fact can make several psi below 2000 rpm when the loads are high. Since the system retains the stock intake manifold, the torque numbers mid and high range are massive. Once I hit 2nd gear I never really leave boost and the fact that is does roll on allows the car to be easily controlled between shifts. Again, since the 928 is basically a mid range and top end car the turbos are sized to hit the sweet spot when you are running flat out but to not be jumpy around town. They are therefore properly sized for a V8. Consider where you shift and where that will land you on the torque curve when the next higher gear is selected. Have you ever driven a properly setup turbo car with an automatic transmission? Well let me tell you, you can load up the engine hard by applying the brake and throttle, basically erasing any vacuum in the engine and in some cases building a bit of boost. Then when you turn it loose, you leave the line with full manifold pressure. The twin turbo Goldmember manages 5.1 seconds 0-60 MPH and it's a silly 1980 3-sp automatic car with a 4.5 liter and tiny K-24 turbos. That car could barely do 8.5 seconds 0-60 when I bought it. It too was very streetable! That's how turbos are used on the drag strip and real world to get to unheard of times with such small displacements.
I don't believe, not for one minute, that the turbo car requires more frequent oil changes at all. As stated, if you follow a regular
diligent standard oil change schudule (as any high performance car owner does anyway), there is no issue. The fact that the system was designed with a 5-minute post shut down water circulation pump makes certain the turbos stay plenty cool. There is
no additional maintenance with a turbocharged engine as you state above. I should know, all three of my cars are turbocharged and my Audi is closing on 300,000 miles and was upgraded to a big KKK RS2 turbo at 200K miles. I've run stock liquid cooled turbos on Audis for 200,000 miles on a standard
5,000 to 7,000 mile oil change interval for 8 years and the turbos are still fine with completely acceptable shaft play. How long does a supercharger last? I ask the question and I'm sure you can give the answer back.
Just like I offered Erik, you are welcome to come here and get a ride in my car. I'll assure you you won't get out and mention the word turbo lag after the experience. I can tip in my throttle 1/3 open and build all my boost at very low RPMs. This coupled with the rest of the system design makes the car incredibly fast. Look at the credentials sheets on my car and then take a look at all the others. It flat out makes more HP and torque than any other system.
Again guys, I do appreciate you coming here to have this debate, I really do. Let's keep it open, honest, and factual. I'll be glad to answer any questions you have or if you want to talk in person feel free to call the business line at 859.781.9288