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AEM on 91 Comptech SC dilemna?

Joined
22 April 2001
Messages
125
Location
West Palm Beach, Florida
I have talked with several people regarding adding the AEM EMS to a 1991 Comptech SC high boost (although I max at about 6.5 psi) with headers and free flow exhaust. NSXRod has one and believes the AEM added 40 HP bringing it to almost 370 total and said he knew others who had similar improvement. I talked to a guy in a tuner shop in Florida who also thought it should be worth 40 HP (actually I think he said about 20%).
However, Chris at Science of Speed, who I would expect to be one of the foremost experts in this said I would probably pick up only about 20 HP and sounded dubious about whether it is worth the extra trouble and expense.
Can others tell me what they have experienced?
 
Re: AEM on 91 Comptech SC dilemna?????

I don't know the HP gains from adding the AEM as I didn't have a before/after dyno....don't think I did. Regardless, I did it for more control of the A/F ratio....just being able to control things throughout the rev range helps me sleep at night. Of course, you have the added $$ of a FPR, Walbro FP, and larger injectors as well. It is now more comforting to rev the car to 7K+ RPM where it's usually lean.

Jeff
 
Re: AEM on 91 Comptech SC dilemna?????

I wonder how many folks out there are even running a/m engine management systems with the CTSC. I thought one of the beauties of that system was it is plug-n-play and you don't have to bother with engine management.
However, if you are running a high boost system and are only seeing ~6psi, then I would then you are losing boost somewhere. I would confirm you have that setup or trace your boost problem and then you would pick up quite a bit of HP. JMHO
 
Re: AEM on 91 Comptech SC dilemna?????

With the Hi-Boost Setup you should see 7 to 7.5lbs of boost throughout your midrange and roll off to around 6.5lbs by 8k RPM. If you are not your belt is slipping or you have a boost leak some where in the system. The issue of engine management on a high boost setup is safety. You need to control timing at higher RPM's.

The CTSC HiBoost was designed to run very rich, (I am assuming of course you have the complete upgrade kit, pulley, injectors, recalibrated FMU) more fuel will only help to a point to control knock, but will quickly become an issue as your system is heat soaked from pushing it hard for a while. Another issue is the fuel itself, when you run on the limits of what is safe any variable can spell disaster.

The AEM will add some performance gains, the biggest improvement is safety. All these things come with the a few negatives, make sure you have a very good NSX/AEM tuner very close by and be prepared for some down time and many tuning sessions if you expect it to be perfect. For us OBD1 guys the AEM ECU is probably the best choice, for the OBD2 guys the AEM FI/C may be the better choice.

I have been running the AEM/CTSC/HiBoost for three years now, I have also taken the time to learn the AEM ECU and how to tune it, but I can tell you I have many hours into my tune, I would hate to think what the real cost of tuning would be if I had to pay someone to tune my car. I am sure others that tune for a living could have got there quicker than I did, but I did learn a lot on the way.

By the way if you do the AEM, you should look at Titanium Dave’s belt adjuster thingy that he makes for the CTSC setup, guys have been getting another half a pound of boost after installing it, that should get you a few more HP.

Best of luck

Dave
 
Re: AEM on 91 Comptech SC dilemna?????

Dave,
Thanks for the good advice. It sounds like you are in he same camp as Chris at Scienc of Speed saying the HP increase won't be big. Do you know your HP? Is your car just AEM, Hi-boost CTSC, headers and exhaust. My coptech set-up is about 5 years old and back then people didn't seem surprised with the 6 lbs boost. Do you know if things have changed along the way?
I will definitely get a belt adjust. Sounds like a few easy HP.
Thanks again.
 
Re: AEM on 91 Comptech SC dilemna?????

I think this was asked in a previous post a long time ago,but I can't seem to find it now...anyway, does anyone have any experience with getting this to pass CA smog on a 91 with a low boost Ctsc? Are there any issues or concerns with this?Please feel free to PM me if you don't wish to reply on this thread.
 
Re: AEM on 91 Comptech SC dilemna?????

<<The AEM will add some performance gains, the biggest improvement is safety. All these things come with the a few negatives, make sure you have a very good NSX/AEM tuner very close by and be prepared for some down time and many tuning sessions if you expect it to be perfect.>>

Shouldn't the programming for people with high boost systems and headers be pretty similar from car to car? Has anyone started with somone else's perfected program and gone from there? I would assume the system still utilizes the knock sensor to provide some automatic adjustment.
 
Re: AEM on 91 Comptech SC dilemna?????

The AEM is my recommendation.
I am very pleased with it. Well worth the money.
safety, service, and service after sale is almost priceless.
The main key is a knowledgeable tuner.
The guys at AEM will add you with any questions as they did for me.
We had to start from scratch with my tune.
I can say my car has 5k miles on it with the AEM and still
running strong.
Though I have a turbo setup with 750 injectors, I would be more
than happy to send you my tune as a starter tune and your tuner can adjust it for your vehicle specifics.

Nook.
 
Re: AEM on 91 Comptech SC dilemna?????

I was told I needed a NSX specific knowledgable tuner to be able to cleanly and properly do the install. (2 1/2 hours away). Would a good non-NSX tuner be able to make the furhter tweaks?
 
Re: AEM on 91 Comptech SC dilemna?????

Dave,
Do you know your HP?..... Do you know if things have changed along the way?

My setup is at 382 RWHP on a Dynajet48X Dyno. I have the older style Comptech Kit, Whipple blower (the newest kits have the Autorotor blower), welded cast intake (some have a two piece design and the real early units were cut and welded from the OEM intake manifolds). I have CT Headers, ARC DTM Exhaust, 9lb pulley, Walbro fuel pump, RC 550cc Injectors, AEM FPR, AEM ECU, Dual Uego O2 sensors, EGT Sensor, Fuel Pressure Sensor, and various other stop faster parts to go with my go faster parts.

While this may or may not seem like a lot of power, it is more than I can use at most road course tracks, if you are looking to build a street fighter out of your CTSC you will quickly reach the limit of the kit and still want more. I love my HiBoost/AEM setup and feel the power level is just about perfect for the track, but if you are not going to track your car. I would give some serious thought to keeping the 6lb pulley in place and not making the move to the AEM. The nice thing about the CTSC 6lb setup is that is so simple and is easily reversed if you ever decided to change the car back to stock. However, it can be allot of fun if you are willing to take on the challenges of an aftermarket ECU.

I am lucky, I have access to the dyno I use anytime I want, so my car has lots of time on the dyno and lots of time on the street logging data and adjusting my calibration file.

I cannot stress it enough the tuner is the key to your cars happiness. If your tuner is looking for a base map to start with, I am not so sure he would be my tuner, the AEM software has a startup cal that any good tuner should be able to start from and build you a custom cal just for your car. I have looked at many cal files from many tuners, some that were held very high in the tuning world, and was surprised and sometimes shocked at what I saw. If your guy can not build the cal for your car, he is not really a tuner, he is a tune loader. I am neither of these things, I will not tune anyone’s car but my own, I am more than happy to help someone solve problems along the way, but I do not feel comfortable with tuning someone else’s car or sharing my finished cal. Every car and setup is different and I would feel horrible if a mistake I made in my tune had caused someone else’s car to fail.

If you have the time and want to learn for about the price of what some tuners charge you can take a tuners course from AEM and learn the programming steps to tune an AEM ECU. You should have a good understanding of how EFI and general engine tuning knowledge prior to taking the course, but that is all I had to go on when I started. I did get lucky enough to have one of the best teachers at AEM.

Just keep in mind, just making the move from the 6lb to the 9lb & AEM will not make a night in day change in the way your car drives, you will feel the difference but you will adjust to the change in power very quickly, too quickly. You need to figure out what you want the car to do then design a system to meet those goals, otherwise or until you know what you want I would leave the 6lb setup in place and enjoy the ride.


Dave
 
Re: AEM on 91 Comptech SC dilemna?????

My setup is at 382 RWHP on a Dynajet48X Dyno. I have the older style Comptech Kit, Whipple blower (the newest kits have the Autorotor blower), welded cast intake (some have a two piece design and the real early units were cut and welded from the OEM intake manifolds). I have CT Headers, ARC DTM Exhaust, 9lb pulley, Walbro fuel pump, RC 550cc Injectors, AEM FPR, AEM ECU, Dual Uego O2 sensors, EGT Sensor, Fuel Pressure Sensor, and various other stop faster parts to go with my go faster parts.

While this may or may not seem like a lot of power, it is more than I can use at most road course tracks, if you are looking to build a street fighter out of your CTSC you will quickly reach the limit of the kit and still want more. I love my HiBoost/AEM setup and feel the power level is just about perfect for the track, but if you are not going to track your car. I would give some serious thought to keeping the 6lb pulley in place and not making the move to the AEM. The nice thing about the CTSC 6lb setup is that is so simple and is easily reversed if you ever decided to change the car back to stock. However, it can be allot of fun if you are willing to take on the challenges of an aftermarket ECU.

I am lucky, I have access to the dyno I use anytime I want, so my car has lots of time on the dyno and lots of time on the street logging data and adjusting my calibration file.

I cannot stress it enough the tuner is the key to your cars happiness. If your tuner is looking for a base map to start with, I am not so sure he would be my tuner, the AEM software has a startup cal that any good tuner should be able to start from and build you a custom cal just for your car. I have looked at many cal files from many tuners, some that were held very high in the tuning world, and was surprised and sometimes shocked at what I saw. If your guy can not build the cal for your car, he is not really a tuner, he is a tune loader. I am neither of these things, I will not tune anyone’s car but my own, I am more than happy to help someone solve problems along the way, but I do not feel comfortable with tuning someone else’s car or sharing my finished cal. Every car and setup is different and I would feel horrible if a mistake I made in my tune had caused someone else’s car to fail.

If you have the time and want to learn for about the price of what some tuners charge you can take a tuners course from AEM and learn the programming steps to tune an AEM ECU. You should have a good understanding of how EFI and general engine tuning knowledge prior to taking the course, but that is all I had to go on when I started. I did get lucky enough to have one of the best teachers at AEM.

Just keep in mind, just making the move from the 6lb to the 9lb & AEM will not make a night in day change in the way your car drives, you will feel the difference but you will adjust to the change in power very quickly, too quickly. You need to figure out what you want the car to do then design a system to meet those goals, otherwise or until you know what you want I would leave the 6lb setup in place and enjoy the ride.


Dave

I was trying to decide if I should to go from the 6lb to 9lb...


One owner who did the same , told me similar----He stated it made a difference but he should have used the 3k some where else. Therefore I got boost/A/F gauge , dali scoop (used), chip , belt tensioner (1 day ago) , tuning and dyno for around 800 and left well enough alone.....After All, I don't track the car....I just get on my r1 when I want a lil more quickness.
 
Consider a simple solution

My .02, based on personal experience with the kit:

If money is not really an issue, the AEM or a similar fully-programmable system is, without a doubt, the best solution. However, the reality is that controlling anything besides fuel is not crucial with that set-up. Timing is a factor, but I, personally, have never seen a proper installation with a functioning stock ignition system where timing actually caused problems. The factory ECU does a really good job of sorting out the timing by itself on simple systems like that.

So, you should give serious thought to a fuel controller like the Neo, which replaced the V-AFC. I have put them on couple of blower cars with very nice results. The CT kit gets you in the rough area for the fuel curve, so a piggy-back system is fine for making the minor adjustments needed to dial it in exactly where you want it. The only issue I have personally encountered is that, on some cars, the ECU tries to compensate for the changes and correct back to the factory settings. The good news is that when this does happen, it is a slow process and re-setting the ECU once a month or so seems to counter it.

An hour or so on the dyno should be fine to tune it in. IIRC, one of the better respected tuner shops on here (Factor X or Autowave) mentioned they did a couple of cars like that and were happy with the results.

Best of luck with your project.
 
Simple solution

Great comment. With good factory ignition conrol and fuel control, shouldn't that get you all the benefits of the AEM? It sounds like an added benefit of the Neo would be simplicity-hopefully no repeated trips to a good tuner which people have been saying is essential to getting the AEM right. It would also retain the diagnostics of the stock ECU which I would have to think would be beneficial in locating problems. David, did you get any horsepower gain? Anyone else have experience or comments on David's route?
 
DDozier
has a very valid point.
I cannot stress it enough the tuner is the key to your cars happiness. If your tuner is looking for a base map to start with, I am not so sure he would be my tuner, the AEM software has a startup cal that any good tuner should be able to start from and build you a custom cal just for your car. I have looked at many cal files from many tuners, some that were held very high in the tuning world, and was surprised and sometimes shocked at what I saw. If your guy can not build the cal for your car, he is not really a tuner, he is a tune loader. I am neither of these things, I will not tune anyone’s car but my own, I am more than happy to help someone solve problems along the way, but I do not feel comfortable with tuning someone else’s car or sharing my finished cal. Every car and setup is different and I would feel horrible if a mistake I made in my tune had caused someone else’s car to fail.

I would only get a tuner that has experience with the AEM. He should be able to make his own map with the base tune from AEM.
I dont believe he has to be the most knowledgeable person with NSX but, definitely with the AEM programing and tuning.
 
Re: Consider a simple solution

Timing is a factor, but I, personally, have never seen a proper installation with a functioning stock ignition system where timing actually caused problems. The factory ECU does a really good job of sorting out the timing by itself on simple systems like that

The biggest issue with the OEM ECU is how you intend to use the car (my comments relate to a 3.0l and a Whipple CTSC setup with the Comptech 9lb kit), if you do the 9lb and you intend to track or push the car hard for an extended period of time you are likely to have an issue with timing. If you are driving your car on the street and doing a few hard runs from stop light to stop light you will be less likely to see a problem.

The Whipple in HiBoost will push your intake temps very high at the track (240-260+ degrees) and while the onset of these higher temps helps as the OEM ECU retards timing based on higher intake temps, the range does not seem to be enough to cover all the bases. Your intake temps continue to climb and the OEM ECU only has one defense left to retard timing and that is based on Knock. If the car was still N/A you would never see these kinds of temps and for that reason no programming was put in place to deal with these issues. Another issue with timing is the OEM ECU seems to be very aggressive about returning timing after a knock event. That means that if all things are the same you will have a second knock event, then a third, and so on. Keep those knock events coming and you keep stressing the piston ring lands and that is the weakest link in the chain.

The OEM ECU as I understand it looks at two things when in closed loop to decide if the timing map needs to be retarded. The IAT (intake air temp) and Knock Sensors are the two sensors that have the most control over timing. If anyone knows exactly what the range of adjustments is they are not talking. The OEM ECU is very smart, and has more than one ignition map and more than one range of adjustments based on conditions seen by these two sensors as well as others, like coolant temp sensors and I believe the TCS may have a play in things as well.

Keep this in mind as well, the CTSC Autorotor kits are seeing issues with knock, that blower is more efficient than the Whipple and will make more boost at a lower intake temp range, the reason the Whipple seems to have less issues with timing is it heats up quicker and operates with higher IAT, and this by design or luck seems to be a better match for the OEM ECU's program.

One other option for controlling all this stuff may be the AEM F/IC, and seems to be a viable option, but it is designed for OBD2 cars. While our OBD1 ECU's are not that different from the OBD2 ECU the fact that we cannot just hook up a scan tool to see important data will make tuning the new F/IC much harder. Without access to live data about fuel trims it is going to mean allot of time adjusting and readjusting the fuel and O2 maps to make the ECU happy. There are a few out there running on the OBD1 cars and if I had not already done the full fuel system upgrade and the AEM ECU I would give this option a serious look. You could probably get away with getting the F/IC and using it just to control timing while under boost.

Sorry for the long post, but there is a lot to this subject and these are the things I have learned after playing with this setup for a little over three years.

Dave
 
Don't stop Dave, keep it coming. We need all of this Proper important info laid out. Not many of us Track our cars, but your prospective on both is great. Also laying down some of the fundamental differences on the old whipple, new autorotor and the different boost is great.
Keep up the good work and make sure your free in a month when I install my used low boost whipple system when my engine is broken in.
We will be hosting a whipple party.
Unfortunately Dick 'Mr. Whipple' Wilson will not be attending, he passed at 91.
Thanks
Trev
 

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I agree completely that if the car is to be tracked regularly and driven hard (more than just routine HDE), then full engine management is a good idea. At that point, you need to think of modifications in a more race-oriented fashion vs the more ordinary street performance.

If not, the NEO should be a fine solution. As for gains, you would see the same improvement that you would get from the fuel trim adjustments with an AEM, but not whatever gains came from timing adjustments. Its impossible for me to say how much that would be, but I suspect it would be 80-90% of the power gain the AEM would show and would give you the safety of not running pig rich at certain rpm points, with is bad for the rings. In my experience, Chris' estimate is more realistic - expect 15 - 20 whp.

As mentioned, the AEM piggy-back unit could also work for you, with the added benefit of retarding timing. I am not sure of the pricing on it, but I don't think the hard ware costs a whole lot more (+ $100?) than the NEO, although the tuning is considerably more involved. It was designed to work with OBD2 cars, but I can't think of a technical reason it shouldn't work fine on yours. You may have the same issue with the ECU trying to correct, but again that is easy to solve by re-setting it periodically.

Best of luck with project.
 
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