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Multiple CTSC dyno runs with fuel pressure adjustments between runs

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Below are dyno runs that I did tonight with changes made to fuel pressure between runs. I'm very interested in getting feedback on my air/fuel ratio. The car is a 92 with 6 PSI CTSC, headers, exhaust and Unifilter. Air/fuel was measured from the bung on my Anytime exhaust with the test pipes replacing the cats. I adjusted the fuel pressure with the vacuum line removed. Comptech's recommend range is 58-62 psi. The runs below are at 60, 62, 63 and 64 psi.

These results look better than with the cats, but still seem slightly lean. Is my air/fuel acceptable and what setting works best?
 
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They still look a little lean. I would be shooting for 12:1 at the highest from 6K to redline. Very consistant though :smile: I bet it is fun to drive.
 
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think you might have posted this before. Your Dyno runs are similar to most of us who have the CTSC. At one time, I had your system with the exception of the CT unifilter and I have the CT exhaust. Your numbers with your setup are going to bounce around that AFR~13 range and there is not much you can do about it. The great limitation of the CT fuel management is that it is a very inaccurate way of tuning. The real question you have to answer for yourself is whether or not you are OK with having a very safe system on your car that has really proven itself over the years to be quite safe or whether you want to spend a couple more grand and get the AEM and flatline the AFR at 12? If you've got even more cash(~$4000), then get the AEM EMS for your 12AFR, get the highboost pulley/550 injectors/wallbro fuel pump and be prepared to get about 50 more rwhp and 40more lbs of torque.
This is ultimately what I ended up doing and it really is a kick in the pants.
RacerXJLing and I have essentially the same system and we are pleased with the results.

Your dilemma is the same as all of us that have had the CTSC. Weigh your options and cashflow to decide what you want.

Good Luck! You are not alone!

Rod
 
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HotRod said:
think you might have posted this before. Your Dyno runs are similar to most of us who have the CTSC. At one time, I had your system with the exception of the CT unifilter and I have the CT exhaust. Your numbers with your setup are going to bounce around that AFR~13 range and there is not much you can do about it. The great limitation of the CT fuel management is that it is a very inaccurate way of tuning. The real question you have to answer for yourself is whether or not you are OK with having a very safe system on your car that has really proven itself over the years to be quite safe or whether you want to spend a couple more grand and get the AEM and flatline the AFR at 12? If you've got even more cash(~$4000), then get the AEM EMS for your 12AFR, get the highboost pulley/550 injectors/wallbro fuel pump and be prepared to get about 50 more rwhp and 40more lbs of torque.
This is ultimately what I ended up doing and it really is a kick in the pants.
RacerXJLing and I have essentially the same system and we are pleased with the results.

Your dilemma is the same as all of us that have had the CTSC. Weigh your options and cashflow to decide what you want.

Good Luck! You are not alone!

Rod

Thanks for your comments. I didn't think anyone was going to respond. These were brand new numbers that I ran last night and were different from previous runs because I ran with no cats and varied fuel pressures.

$4,000? I thought high boost was $1000 and AEM was $1000. Where does the other $2000 come from.

Funny thing I've noticed is that dynos that I've seen with the high boost kit (bigger injectors) have better air/fuel numbers. I wonder if its safer to run the high boost kit than the low boost kit.
 
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The extra money comes with the tuning time and other accessories to make your system more safe and better performing. The Map for the AEM is not just plug and play. The tuner will need to program the AEM to get you the AFR and Power numbers you request. This may take days if not weeks depending on how much of the information your tuner has. Most people tuning the AEM are not likely to give out their info so the person doing your tuning may have to begin from scratch. Developing your car into a high HP machine is not like an erector set. You just can't put the pieces together and expect it to pound out the HP. The installation of the Wallbro fuel pump for safety in your 13yr old car(~$200 for the pump alone), High boost pulley_(~300?$),New fuel filter, new injectors(~$600/6 cylinders), new plugs(Cu is cooler) and especially the dyno pulls and tuning time, will probable easily run you that extra 2 grand.

Also don't listen to guys who say I don't like your AFR bounding around the 13+ zone with the low boost CTSC. That really is a lot of BS! Comptech has set up a system which is safer than anything on the market and has stood the test of time. Any of the other systems have had problems of probably 20 times magnitude over the CTSC system that you have. Because some guys think that they don't see what they want to see does not make the system unsafe. This is not conjecture, it is fact. If you like the way your car runs now, enjoy your investment. If you want the flatline AFR, then go out and get it.

Rod
 
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Gobble,
I second everything Hotrod said. The number look fine, drive it and don't worry. If you want more power, spend the money and go AEM and a high boost pulley, fuel system, wide band A/F, injectors, I am doing that right now. I already had the fuel pump installed, but other than that I have about $2400 in parts, from slowly getting things used or on sale. I will do the install, then I am budgeting 1/2 day of dyno tuning to make it safe, $400-800. I will do the final drive-ablity tuning my self, it is pretty easy to do, just monotonous like most computer thing. I might come in at $3000, but I doubt it. That speed crack pipe thing...

You do have another option which Shane at Autowave in Huntington Beach set up on the car I have, that is a Walbro 225 fuel pump and a re-curved RRFPR and delete the voltage doubler relay that kicks up the output of the stock fuel pump. My car is rich as a pig, still pulls close to the same HP as your, but I am wiping carbon out of the tail pipe all the time!
 
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Two follow up questions if I can:

1. Of the four charts I posted, which looks the best?

2. Do most with the high boost kit buy the whole thing from Comptech or buy the parts separate?
 
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gobble said:
Two follow up questions if I can:

1. Of the four charts I posted, which looks the best?

2. Do most with the high boost kit buy the whole thing from Comptech or buy the parts separate?

I would go with the 64 lbs. graph.

You have 2 basic ways to go high boost. Comptech sells an upgrade kit with smaller pulley, bigger injectors, re-curved RRFPR, might also have a fuel pump. This still has the problem of no real tuneing option, or fuel control, but it is pretty much plug and play.

Most will do the AEM set up because you can control the fuel and timing to get some big gains in power. It also have wide band O2 sensors to data log and do your own tuning on the road, not just in the shop. It is pretty easy to get the parts together yourself or buy a complete set up. here are the parts I am using:

AEM ECU 30-1002
AEM Wideband, dual 30-2300
AEM FPR 25-302
GM air temp sensor 25036751
Comptech pulley 3.9" 352-077
RC Engineering injectors, SL4-550

I will do the initial tuning with stock plugs and then adjust if I need to go cooler. Will also use some GM top end cleaner before the install to clean out any carbon deposit which should help with the inital tuning. The install will take a while, need to reverse the MAP sensor electronic clamp in the wire harness, use stock MAP sensor, wire in new air temp sensor and all the junk for the dual wide band as well as the pulley and injectors.
 
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AEM ECU 30-1002
AEM Wideband, dual 30-2300
AEM FPR 25-302
GM air temp sensor 25036751
Comptech pulley 3.9" 352-077
RC Engineering injectors, SL4-550


Fantastic information, thanks! I've always "kind of" had an idea of what was needed, but never spelt out explicitly like this. A question: if I intend on eventually going AEM, is it a waste of money to get the hi-boost kit? ie am I going to be replacing everything that comes in the kit other than the pulley? I'm assuming the higher flow injectors that come in the kit would be replaced yet again with the 550's? What else does the hi-boost come with?

Another question... I'd like to replace my existing fuel pump with the walbro irrespective of whether I do anything further with my 6lb CTSC. I'm still not clear on whether it's a straight replacement or whether modifications have to be made for fuel return etc because of the additional flow?
 
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Arshad said:

AEM ECU 30-1002
AEM Wideband, dual 30-2300
AEM FPR 25-302
GM air temp sensor 25036751
Comptech pulley 3.9" 352-077
RC Engineering injectors, SL4-550


Fantastic information, thanks! I've always "kind of" had an idea of what was needed, but never spelt out explicitly like this. A question: if I intend on eventually going AEM, is it a waste of money to get the hi-boost kit? ie am I going to be replacing everything that comes in the kit other than the pulley? I'm assuming the higher flow injectors that come in the kit would be replaced yet again with the 550's? What else does the hi-boost come with?

Another question... I'd like to replace my existing fuel pump with the walbro irrespective of whether I do anything further with my 6lb CTSC. I'm still not clear on whether it's a straight replacement or whether modifications have to be made for fuel return etc because of the additional flow?
If you are going to go AEM, don't waste money on a step in between, IMO. :biggrin: The adjantages of the AEM are enormous for tuneing, both for power and safety.

SOS sells a Walbro pump which is a 'plug and play', I think it may be just a plug they have attached for you. That said, it is about the same price I see every where for the pump so send your money to Chris for his support. :wink: The lines on the Comptech RRFPR are plenty big enough for the return.
 
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I concur w/ HotRod. I am very pleased w/ the results. The car pulls hard and dyno shows it is safe. Also, my car (I am sure as HotRod's) is tuned w/ crappy 91 octane fuel. Shane @ Autowave is also very conservative to be on the safe side of the AFRs. Good luck.

Jeff
 
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gobble said:
By turning the screw on the bottom of the fuel pressure regulator.
This 'should' only adjust the base fuel pressure and not effect the pressure through out the curve which is controled by the spring in the FPR. It's cool you were able to get some control with it, mine seemed to have no repeatable effect when I made adjustments.
 
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ibDursty said:
Just curious.. if you go with AEM do you have any problems passing state emmisions (for states that test every year or two)?
With the AEM you can tune the car any way you want, you may end up with 2 different maps, 'power tune' and 'emmission tune', but they are easy to load and change with a lap top computer. All this is assuming you are OBD 1, OBD 2 will not pass, I am pretty sure.
 
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titaniumdave said:
This 'should' only adjust the base fuel pressure and not effect the pressure through out the curve which is controled by the spring in the FPR. It's cool you were able to get some control with it, mine seemed to have no repeatable effect when I made adjustments.

Mu understand is that it increases pressure across the entire range. If I have a base pressure of 50, it goes to 90 at full boost. If I start at 45, I only get to 85-86 at full boost.
 
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titaniumdave said:
This 'should' only adjust the base fuel pressure and not effect the pressure through out the curve which is controled by the spring in the FPR. It's cool you were able to get some control with it, mine seemed to have no repeatable effect when I made adjustments.

I've never looked into the AEM and don't know anything about it. Could someone who knows a bit about cars and computers research this on his own and do the tuning by himself? Or is it best left to someone who is experienced with the system? I'll probably never make the jump, but it sounds fun and high tech.
 
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gobble said:
Mu understand is that it increases pressure across the entire range. If I have a base pressure of 50, it goes to 90 at full boost. If I start at 45, I only get to 85-86 at full boost.
With mine on the dyno the pressure would top out at 90 PSI @ 7200 RPM, no matter what I did with the base pressure.
 
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