After contemplating between a P600-B and a D1, I decided to go for a D1 with a 10 lbs pulley for my 1990 L98. The reason behind my decision was lower noise levels because of the helical cut gear in D1 versus straight cut gears in P-600B. This D1 is not a self contained unit (not a D1-SC model). At first, I was leery about poking the hole in my oil pan but after doing a little research I thought it was ok. D1-SC is not available for L-98.

I bought the kit from Mike at superchargersonline.com and paid $3850 for the kit.

My car was at the shop for almost a couple of months because of all the problems with the "so-called complete kit". Just to let you know, nothing could be far from the truth. My mechanic whined about ATI Procharger's lack of technical support and their attitude every single time I called him . But finally the day came when it was ready. I also got the Autometer Fuel Pressure gauge and the Boost gauge and got those installed on the A-Pillar.

My experience so far with the D1 is as follows:

At first when I started the car, I felt it was still too noisy. It felt like something was rattling in addition to the supercharger whine. Now after about a couple weeks, the noise has died down quite a lot and you can only hear the whine in idle. At throttle, I do not hear any noise whatsoever. I had measured the sound level in my car with a sound meter before putting in the supercharer and the max was at 105 dBA. The superchargers noise is around 95 dBA or so I was told, but the point is that to my ears it is not bothersome at all, especially given that it is already lower than my exhaust sound levels.

As far as the power goes, I used a GTech Pro Competition meter to measure 0-60. A friend of mine who has a 2001 Z06 and I both ran 0-60 and the times were 4.9 seconds for my supercharged Vette (which has Auto transmission) and the Z06 hit a 5.1 (yes it was 1/10th of a second slower), both on street tires. My Z06 friend also got better numbers on my car as compared to his own Z06. I have yet to do 1/4 mile runs. The GTech Pro meter reported (rwhp) 443.5 HP and 517.7 ft-lbs of torque for my 4.9 seconds run. I am not sure how good are these numbers. I will take it to a shop to get the real dyno numbers.

On my boost gauge, the boost starts increasing when the RPM goes above 2500. At about 4000 RPM, it goes to 5 or 6 psi and just before the redline at about 4900 RPM, it hits 10 psi. Now what I would really like is to get higher boost at lower RPMs, say at around 2250 RPM, I would like to get at least 5 psi or even higher . I would really appreciate any advice. Do you think addition Nitrous would help? Would I really get any major gains using nitrous? Any detrimental effects on the engine?

The second major problem is that after the supercharger installation, the hood can not be kept open without holding it. The shock that holds the hood open needed to be re-located but there was no bracket that came with the kit. The ATI told us to call GM for that bracket. GM said it was a discontinued item and the mechanic threw his hands up in the air and now I am stuck with a hood that someone needs to hold to keep it open. I remember reading a post earlier that mentioned the exact same problem and also a solution. I did a search in the archive but couldn't find anything on it. I would really appreciate any help.

The third problem is that the Check Gauges light came on after the supercharger installation although all the gauges are working fine. According to the mechanic, it might have happened because he had to disconnect the sending unit to run the oil tap line from the supercharger. I do not understand what is really going on. I was thinking disconnecting the negative terminal of the battery and hence resetting it might resolve the problem. Any ideas?


Thanks in advance

Raheel

 

to the mechanic, it might have happened because he had to disconnect the sending unit to run the oil tap line from the supercharger.


Did he reconnect it? The CCM will may be looking for the engine oil temperature switch if he disconnected it and forgot to put it back......just a thought

 

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At first, I was leery about poking the hole in my oil pan but after doing a little research I thought it was ok. D1-SC is not available for L-98.
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I feel that this is a better route, as the SC always receives fresh oil. There are differing opinions on this matter. Try changing the oil on a self contained unit.

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My car was at the shop for almost a couple of months because of all the problems with the "so-called complete kit". Just to let you know, nothing could be far from the truth. My mechanic whined about ATI Procharger's lack of technical support and their attitude every single time I called him . But finally the day came when it was ready. I also got the Autometer Fuel Pressure gauge and the Boost gauge and got those installed on the A-Pillar.
_____________


These kits require the installer to have some sence of mechanical ability, as all of the cars (85-91) are not identical. That is why you took it to someone else who you thought had the mechanical aptitude to complete the task. As it has been said so many times before, these are not just a bolt on and forget it type modification. This is just the beginning of your journey.


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The GTech Pro meter reported (rwhp) 443.5 HP and 517.7 ft-lbs of torque for my 4.9 seconds run. I am not sure how good are these numbers. I will take it to a shop to get the real dyno numbers.
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If your car was stock, I would feel that these numbers may be a bit optimistic. Only you can know if the numbers seem right. In my experience ATI's systems seem to add between 30-55% power increase on the L-98 cars.

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On my boost gauge, the boost starts increasing when the RPM goes above 2500. At about 4000 RPM, it goes to 5 or 6 psi and just before the redline at about 4900 RPM, it hits 10 psi. Now what I would really like is to get higher boost at lower RPMs, say at around 2250 RPM, I would like to get at least 5 psi or even higher.
_________________


Airflow (or as you make reference to boost) is mathmatical relationship to RPM. In this case if you were to increase airflow (boost) at a lower RPM (through pulley swap), then it would likewise increase on the topend. THis may very possibly overspeed the blower. Do the calculations based on the pulley sizes, and determine if you are approaching max impellor speed.

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Do you think addition Nitrous would help? Would I really get any major gains using nitrous? Any detrimental effects on the engine?
_______________


Nitrous should not be used below 3000 RPM, per the manufacturers recommendation.

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The second major problem is that after the supercharger installation, the hood can not be kept open without holding it. The shock that holds the hood open needed to be re-located but there was no bracket that came with the kit. The ATI told us to call GM for that bracket. GM said it was a discontinued item and the mechanic threw his hands up in the air and now I am stuck with a hood that someone needs to hold to keep it open. I remember reading a post earlier that mentioned the exact same problem and also a solution. I did a search in the archive but couldn't find anything on it. I would really appreciate any help.
________________


Three solutions: use the assist shocks that were available on the very late C-4s, or locate a scissors type set-up that came on the 84-85s, or relocate the factory set-up over to the passenger side. The first solution does not offer much assist in the lidting phase, until the hood is approx 3/4 open (look at the leverage point of your hinges). The shocks will hold the hood open though. The second option should be available from many of the wrecking yards, as these were used on many cars. The third option requires the mirror image bracket of what was removed from the driver's side. This is not available from GM. You will have to make the bracket yourself. and also install the hood support nutplates into the passenger side. I chose option 3.

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The third problem is that the Check Gauges light came on after the supercharger installation although all the gauges are working fine. According to the mechanic, it might have happened because he had to disconnect the sending unit to run the oil tap line from the supercharger. I do not understand what is really going on. I was thinking disconnecting the negative terminal of the battery and hence resetting it might resolve the problem. Any ideas?
_________________


If the mechanice did not reinstall the sensor, then this will cause an issue with your gauges. The sensor is very hard to install as described by ATI. You will have to by the shortest pipe nipple (sold as "close") to install between the block and the "T". I had to actually shorten the block side mount to get enough clearance to be able to spin the T onto the nipple. You can not shorten the T on the sensor side mount, otherwise it will restrict flow to the SC oiul feed line.


Hope this helps,
Aaron

 

love my D-1 on my L98 makes good power and allot of fun!

 

There's no new bracket; just play with it. I elongated the existing holes and moved the hood end over. You can also flip the strut from the right to left side of the forward bracket. If not, the earlier scissors support works nicely.

Also "check gauges" doesn't mean there's a problem with the gauges, it means check the gauges cause there's a problem with the engine! Are you running MAF? Are your injectors at least 36lb/hr ? Have you done your dyno tuning of the ECM? If you've answered yes to any of these, more than likely it's not running right. But it doesn't hurt to check all the sender connections; there are different senders going to the ECM vs. dash gauges.

 

Are you sure you have the knowledge to be playing around with this? Please find a tuner before you destroy your engine...

The airflow of a centrifugal compressor increases with the square of RPM; i.e. 2x the RPM gives 4x the airflow (and approx 4x the boost). If you want 5psi around 2200rpm, at 4400rpm you'll have around 20psi and blow your engine apart before you get close to redline.

You work with pulley sizes to set the max to a safe level at redline. Then it is what it is at lower rpm:
12psi @ 5500 means 3psi at 2750, etc, etc.

Once it's properly set up you shouldn't have any trouble making what you need from a D-1. I have the smaller P600B and make over 450 ft-lbs at the wheels from 2700-5500rpm.

 

Thanks to all of you for your advice. I have compiled the responses and faxed it to my mechanic. I will talk to him tomorrow and find out what does he have to say in response to all the advice and recommendations regarding the check gauges light and the hood problem.

In the meantime, I took my car to get the dyno done. During the dyno, the boost gauge never hit 10 psi (which I do normally hit on the street at higher rpm) because the guy pressing the throttle didn't really know what (and how) was he supposed to do. Irony of fate, he didn't speak any English and I couldn't speak any of the oriental languages :rolleyes: The maximum boost that I saw during the dyno run was around 7 - 8 psi.

Anyway, the numbers when plotted against speed or time show up as follows:

Max HP (rear wheel): 333.09
Max Torque (rear wheel): 488.96

When plotted against RPM, the numbers change to

Max HP (rear wheel): 240.97
Max Torque (rear wheel): 284.36

I do not understand why is there such a big difference between the first one and the second one. Shouldn't the numbers stay the same regardless of if they are plotted against time, speed or rpm? How could there be a difference of almost 200 lb-fts of torque and 100 hp between the two?

I don't know how to post the pictures so here is the link to the dyno charts:

http://www.raheelkamal.com/sports_cars.htm

BTW, I do not have a lot of knowledge but I am trying to learn and have learnt a lot from this forum.