I drove the twin turbo
10-10-2007, 02:40 PM
#1
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I drove the twin turbo
Kind of a late post, but I have had a killer work-week. Sunday, I made the trip down to northern kentucky to see john. Last i saw the car was SITM, and it had just been finished up for the drive, and had several tuning quirks (lumpy/unstable idle). Some road/dyno tuning in the meantime has solved most of the problems, and the dyno graphs posted on Pelican say 515 HP and 514 Ftlbs at the wheels.
John took the car out for a drive down some familiar back roads near his house, and then a mixed drive of interstate and in-town to give a good impression of the cars capabilities. On the back roads, he was able to get it to slide out sideways in second, and again in third, leaving behind long patches of rubber. Cruising on the freeway is in no way adversely effected by the turbos. The car sounds like any other car with gt resonators and RMB. The throttle response at cruising speeds, above 2200 RPM is just amazing. The turbos roll on hard, and have a great sound. He used factory by-pass valves, as used by audi on their S4 motor, so the only noise is the (IMHO) pleasant whir of the turbos spooling, but no rice noises. In town, the car was incredibly well behaved. The way the turbos develop their power allows you to drive the 928 with little difference than stock, or really lay it on. I was very impressed by the dichotomous nature of the beast, in that you could drive it like any other 928, and never even feel/hear the turbos, or just go nuts, and not even be able to hook up the 10" rubber in 1st.
He then let me drive the car. Unfortunately for me, i have been driving my 86 audi 4000 daily for the past 8 months, and am essentially brainwashed to the standard shift pattern, and characteristic of my clutch. I have to admit that i stalled the car out twice trying to get used to the 928 clutch. Needless to say, i was never able to push the car to its true limits. As part of the turbo conversion, John put in a spec clutch and pressure plate to hold up to the new power level. It has a great action once you get used to it, very button like, but is tricky to get started. I imagine like with most cars, a few hours behind the wheel would acclimate you to just about any clutch, but I only drove the car for about a half hour or so. The car has an amazing feel. I dont know exactly what to say about performance, but can answer questions if anyone has any. I would say that this car would have a high wife-acceptance-factor, in that you can drive it totally normally, and even let her drive it without ever dipping into the massive power reserves.
There were some perceived rough spots in the air/fuel mixture down below. I could feel a faint hick-up that i would estimate was around 1200 - 1500 rpm. I was talking to john about doing true dyno tuning, and mentioned that there were some limitation in the sharktuner which wont allow for both ignition and fuel tuning at the same time. I imagine that there is more power in the car if both could be tweaked simultaneously, or if he rented the dyno for a multi-hour session. He did comment that when he finished up the current map on the car, the dyno room was 90 degree ambient temperature, and there was little moving air to help out his air-to-air inter coolers. At any rate, this is going to be one serious piece of kit. I think i am going to have to drive up to michigan to experience the twinscrew project to make a comparison, as i have yet to ride or drive in a DR car... or a Murph stage 3. I can say though that the 928 chassis seems to really respond well to high levels of power and torque, and I really encourage anyone with the funds to investigate some forced induction kit. It really makes all the other attributes of the car shine.
Hans
John took the car out for a drive down some familiar back roads near his house, and then a mixed drive of interstate and in-town to give a good impression of the cars capabilities. On the back roads, he was able to get it to slide out sideways in second, and again in third, leaving behind long patches of rubber. Cruising on the freeway is in no way adversely effected by the turbos. The car sounds like any other car with gt resonators and RMB. The throttle response at cruising speeds, above 2200 RPM is just amazing. The turbos roll on hard, and have a great sound. He used factory by-pass valves, as used by audi on their S4 motor, so the only noise is the (IMHO) pleasant whir of the turbos spooling, but no rice noises. In town, the car was incredibly well behaved. The way the turbos develop their power allows you to drive the 928 with little difference than stock, or really lay it on. I was very impressed by the dichotomous nature of the beast, in that you could drive it like any other 928, and never even feel/hear the turbos, or just go nuts, and not even be able to hook up the 10" rubber in 1st.
He then let me drive the car. Unfortunately for me, i have been driving my 86 audi 4000 daily for the past 8 months, and am essentially brainwashed to the standard shift pattern, and characteristic of my clutch. I have to admit that i stalled the car out twice trying to get used to the 928 clutch. Needless to say, i was never able to push the car to its true limits. As part of the turbo conversion, John put in a spec clutch and pressure plate to hold up to the new power level. It has a great action once you get used to it, very button like, but is tricky to get started. I imagine like with most cars, a few hours behind the wheel would acclimate you to just about any clutch, but I only drove the car for about a half hour or so. The car has an amazing feel. I dont know exactly what to say about performance, but can answer questions if anyone has any. I would say that this car would have a high wife-acceptance-factor, in that you can drive it totally normally, and even let her drive it without ever dipping into the massive power reserves.
There were some perceived rough spots in the air/fuel mixture down below. I could feel a faint hick-up that i would estimate was around 1200 - 1500 rpm. I was talking to john about doing true dyno tuning, and mentioned that there were some limitation in the sharktuner which wont allow for both ignition and fuel tuning at the same time. I imagine that there is more power in the car if both could be tweaked simultaneously, or if he rented the dyno for a multi-hour session. He did comment that when he finished up the current map on the car, the dyno room was 90 degree ambient temperature, and there was little moving air to help out his air-to-air inter coolers. At any rate, this is going to be one serious piece of kit. I think i am going to have to drive up to michigan to experience the twinscrew project to make a comparison, as i have yet to ride or drive in a DR car... or a Murph stage 3. I can say though that the 928 chassis seems to really respond well to high levels of power and torque, and I really encourage anyone with the funds to investigate some forced induction kit. It really makes all the other attributes of the car shine.
Hans
10-10-2007, 03:02 PM
#4
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10-10-2007, 03:04 PM
#5
Man of many SIGs
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Great report Hans. I would suggest copying and pasting that post into a word document and saving it for posterity. I have had posts involving that builder dissapear in the past due to some sort of personal animosity towards him by our exalted class here on the list.
10-10-2007, 03:09 PM
#6
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Thread Starter
Yes, its Johns twin turbo. He doenst post here anymore, but most of the build threads can be found on the Pelican forums. Its a pretty amazing car. As I understand it, he is working out ways to duplicate the kit, but it will have a much higher price tag than any of the supercharged options or the single rear mount turbos. I would forsee a price tag well below stroker, but higher than the $7kish price of the super options.
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10-10-2007, 03:22 PM
#8
Man of many SIGs
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Yes, its Schmoopie twin turbo. He doenst post here anymore, but most of the build threads can be found on the Pelican forums. Its a pretty amazing car. As I understand it, he is working out ways to duplicate the ***, but it will have a much higher ***** tag than any of the ************ ******* or the single rear mount turbos. I would forsee a price tag well below stroker, but higher than the $*kish price of the super options.
You are getting dangerously close to verboten speech. I suggest editing that last post and removing any reference to pricing or products that may come up for sale one day. Keep to the review and the facts and your thread may survive. BTW, we decided in a previous thread to use the nome de plume of schmoopie to describe this builder.
10-10-2007, 03:27 PM
#9
Captain Obvious
Super User
Super User
You are getting dangerously close to verboten speech. I suggest editing that last post and removing any reference to pricing or products that may come up for sale one day. Keep to the review and the facts and your thread may survive. BTW, we decided in a previous thread to use the nome de plume of schmoopie to describe this builder.
Careful there….you are turning into Randy!
10-10-2007, 03:48 PM
#11
Race Director
Yet another sweet boosted 928 out there!! It would be very interesting to see the dyno sheet compared to the Murf Stage 3 kit.... Since they both make similar power
10-10-2007, 03:51 PM
#12
Rennlist Member
I think he has built an incredible car. I know personalities on this board collided and thats too bad. I think he was an assett to the 928 community here. I am impressed with all of the innovations for the 928 that give us so many new options for increased performance.
I will be adding force feeding to my car in the next 3-5 years and love the fact that I have options. I don't think I will go with the TT route; but I still think it totally rocks.
I will be adding force feeding to my car in the next 3-5 years and love the fact that I have options. I don't think I will go with the TT route; but I still think it totally rocks.
10-10-2007, 04:19 PM
#13
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Thread Starter
I am not advertising for John, or have any clue what the price will be, I just know it will be higher than current options, and only stated such so that people can have a little more information. It hard to compare kits without having some frame of reference. It will not really compete against the current products, as it will have a noticeable price premium.
John has the car conservatively tuned, as it is running on a stock motor with over 175k miles on the clock. I see the advantage of this kit more-so to those who plan on rebuilding the motor to a lower compression ratio. The turbos used in the kit have plenty of overhead when used on a 5L motor. *Theoretically* with a lower compression in the 8.5:1 range, these turbos could push out some serious boost, possibly breaking the 600 mark without much issue. Look at the 951's turning over 400hp, i dont see any reason why a properly built motor could reach 120hp/liter in our configuration. Then again, i really cant see any reason why someone would want that much power in a daily driver either.
John has the car conservatively tuned, as it is running on a stock motor with over 175k miles on the clock. I see the advantage of this kit more-so to those who plan on rebuilding the motor to a lower compression ratio. The turbos used in the kit have plenty of overhead when used on a 5L motor. *Theoretically* with a lower compression in the 8.5:1 range, these turbos could push out some serious boost, possibly breaking the 600 mark without much issue. Look at the 951's turning over 400hp, i dont see any reason why a properly built motor could reach 120hp/liter in our configuration. Then again, i really cant see any reason why someone would want that much power in a daily driver either.
10-10-2007, 04:21 PM
#14
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