dprantl

Ok, so... the real definition of turbo lag is the amount of time between when you floor the accelerator to the time you have full boost available. It has nothing to do with how fast the car feels. Since a 928 is fast even with no boost at all, it still feels fast when you are experiencing turbo lag. Turbo lag is not how much slower the car is by the addition of exhaust back pressure due to the turbo.

For any given turbo system configuration, there is a maximum theoretical boost at every RPM point. The amount of time it takes when you floor the accelerator to get to that maximum boost point is what people refer to as turbo lag. This is easy to see on a variable load dyno that can keep wheel speed constant. On a supercharged car, there is no lag because the instant you floor the car, you are getting that theoretical RPM/boost limit.

Dan
'91 928GT S/C 475hp/460lb.ft

killav

Right!, The cool thing is the Dynatech is a straight through design, so the turbine can still be seen spinning. It does spin at idle fyi but just spins pretty slow.

killav

Dan,

That is a better description than I could come up with. When I get the PCV deal done, I will grab my video camera, focus in on the gauges, and let her rip from a dead stop. Although acceleration always seems slower than it is on video, it will be easy to see what the boost guage is doing in relation to RPM/speedo readings.

dprantl

You know I have been dreaming about adding turbos to a 928 for years. Can't wait to see more of the car in action.

Dan
'91 928GT S/C 475hp/460lb.ft

namasgt

This past Saturday I had the opportunity to ride in Mikes 87 turbo, so I thought I should give my feedback on his setup, since I was very impressed with the performance. He is running with only 7 pounds of boost and has not completely finished shark tuning it, which he plans to get done on a chassis dyno.

I was seated in the passenger seat and Mike start driving the car normally around the streets to get the engine to operating temperature. My impression was that the car felt like a healthy stock, naturally aspired S4, maybe even a little stronger than what you would expect from an automatic S4. No whistling sound like you would hear on some of the supercharged units. The exhaust sounded just about right, not too loud and not too quiet, engine felt very smooth. In a nutshell it still felt like a gentleman’s car that you would take out for special occasions.

So the engine warms up and we get on the HWY. He down shifts to a lower gear and pushes the throttle to the floor. My first impression was that there was no lag at all, the response was immediate. It was as if you had all that energy stored and all you had to do was push the pedal to get instant access to it. My second impression, well, let me just say that I was never scared this much riding in a car, it got up to speed fairly quickly, cars that were once driving next to us had turned in to little dots in the mirror. I remember him pointing at the boost gauge but didn’t understand what he wanted me to look at; I could not get my attention off the monstrous sound the engine was making paralleled to the sound of the turbo sucking all the air in to feed it. It wasn’t until we got back to the streets driving at posted speed limits at low RPM that I realized that every time he pushed on the gas pedal the analog boost gauge would move to the number 7 instantly, it was as if the gauge was connected to the pedal. So now I can actually say from experience, that there is no lag at all on the system he has installed. Comrades that have commented on the lag issue should definitely ride in this car and I am positive that they would change their mind.
This is one of those rare occasions in the car hobby that you can say “money well spent”.

killav

Ali thanks for the kudos my man.

This system made an already great car even better. A good dyno session and this thing is gonna be even more rediculous.

The PCV system I came up with is working really well. No oil puking out of the filter and it looks like the catch can is working and draining any oil back into the pan.

soontobered84

I have ridden with Mike also. Pre and post turbo. He was in the early stages of sharktuning post-turbo. A sport bike passed us by. I looked over and Mike had this look on his face. I thought "oh $hit, he's gonna run down and pass that sport bike." I grabbed anything I could hang on to and steeled myself for the acceleration exhilaration that I was sure was getting ready to occur. I waited and waited and waited. Probably 7-10 seconds. I finally looked over and Mike had a big grin on his face. He said, "Do you know how hard that was, not to go after that bike?"
I will say that I agree with namasgt's (Ali's) assessment above. Mike's car is a beast, it's really fast, and the turbo kit was money well spent.

Iwanna928

I have loved STS turbos from the start. Any research reveals that they work as they should w/ no lag! To many out there, a ton of satisfied customers.

A job well done!

Were is the CIS setup!

Stephen

killav

I finally might be back in business with finishing up the tune. I recieved the LM-1 today and have it wired up and ready to go!

killav

I had to get my car smog checked for the last time today. Unless the law changes, cars only have to go through the smog check for their first 25 years (in Texas anyway). My car BARELY passed last year. This is prior to me adding the turbo. I was running stock 19lb injectors and an x-pipe with the high flow cats. Also, no sharktuning at this point. My NOx last year was initially over 1200 with the limit at 1000/1100 range. The only way I got it to pass was having the operator take the car to a lower gear opening the throttle more, and adding more fuel, which I am guessing helped quench the combustion chamber and lowered the Nox to just barely passing.

Fast forward to today, and I was really sweating getting my car to pass after changing the car so much from last time. Different injectors (24lbs), different tune, different CAT, etc. etc. I was shocked when the guy told me that the car passed with flying colors. He told me that the readings were lower than most cars he has to dyno (most cars before 2002 or so require this).

The kit comes with a Y-pipe that goes to a single CAT. I guess it's enough to do the job cause the numbers speak for themselves. I have also spent many hours tuning the idle and cruise maps which has got to help. Anyway, I thought this was great news for anybody that has to go through the emmisions process.

And as far as visual, he didn't even pop the hood. I have no idea why. And I also had to stop him from shoving the 2 foot long probe into the spinning turbine! He just gave me a weird look when I told him that he can't stick it all the way in!! He handed it to me and told me to stick it in. Classic.

SeanR

Sweet numbers.

I'll have Pele's car done today (I think). Boost vac line was off above the large boot.

Courtshark

Had the same experience with my old Saab SPG that was running 25 psi of boost. Cleaner than most cars they'd tested. I think it's all of the Italian tune-ups these boosted rides get.

Just read through this whole thread. Fantastic stuff; a huge thank-you for being the guinea pig. Once I get my new-to-me lagoony sorted out, I expect to install an RMB. Debating going with the larger turbo; not really interested in 600hp, though, because I'd probably kill myself going that fast. I have a lot of experience with turbocharging from my Saab-modifying days; the fuel tuning is always the hardest. At 25 psi (9:1 compression), I had to install water injection (Aquamist; used on Lingenfelter Corvettes; http://www.aquamist.co.uk/) to control detonation; the stock intercooler was too small to be adequately effective to reduce the charge-air temp. Have you tried to measure the charge-air temp off this turbo? I think with that long of a run back to the engine the temps should be fine, and thus not needing an IC or water injection. That said, the water injection substantially reduces the charge air temps and resulted in a huge power increase.

killav

I have a basic water/methanol injection kit that I purchased from Coolingmist.com that I have yet to install. That is next on the list.

hacker-pschorr

I see you are using the cigarette lighter plug for the LM-1.

Double check how well your cigarette lighter is wired, many people have experienced erroneous readings / issues with iffy grounds on most lighter plugs.

If you are 100% set on using the plug (versus running a dedicated wire), I would run a new ground to the plug itself just to be safe. It's always best to have the Innovate equipment grounded directly to the block.

killav

Hacker,

Thanks for the info. John S. and Jim C. had warned me of this same thing. I have been using the cigarette lighter and so far have not noticed anything erroneous. The two cars I have tuned with it seemed to work great.

But, I would like to know a good place to pull the power from that is somewhat easy enough to get to on every car. It is super convenient when tuning the car to just plug this thing into the cigarette lighter......