My first time

kookoo4nsx said:

If you have a high boost S/C, why not take advantage of it? If you read through all the old CTSC posts, almost every driver loves the newfound power right away but then finds out that 330rwhp is not REALLY enough.

Why go to all the trouble if so many before you have felt a little "disappointed"? I say, go for the high boost right away. You will pull out an additional 40hp/Tq with a conservative tune and that should get you over 380rwhp without any real additional risk.

Good luck with whatever you decide.

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To be honest seat of the pants the HiBoost does not really add that much overall. You end up with a slightly higher peak HP about 10 lbs more TQ through the middle and even hotter than the normal hot IAT's that the CTSC offers. I did it on my '91 and I tracked it.

The biggest issue is and always will be IAT's with the CTSC design, you may get to 370-380 whp on a dyno but put the car on a track by lap 3 you will end up making 320-330 whp after it heat soaks and the ECU pulls timing. On the street you get to play a little longer but a 1-2-3 gear pull will put the IAT's in the 190-210 degree range and the car will just pull timing and add fuel and you will loose power.

Heat is the cause of most engine stress, so if you can cool the charge temps down to 120-140 range and keep oil temps under control less than 250, the 3.2l with a good tune will last a very long time. The 3.2l are more expensive to rebuild and will require either a new block or sleeves so it is best to take caution in your search for more power.

Dave

My first FI part just arrived. Just received the FI/C, here we go :biggrin:

If i keep getting parts at the hotel i'll be able to build a car in my room. Already have the pride v2, test pipes and some cf mirrors sitting here. Tomorrow i'll be picking up a R hood and next week the SC will be here


Mike

Wow, I had no idea that you could loose 50hp in just a few laps. I guess the advantage of the turbo is once the air is compressed, it has 5-6ft of piping with which to cool off vs the S/C which sits on top of a hot block.

I guess that heat also plagues low boost s/c's so using your math, you loose 50hp with a high boost, a low boost CTSC with heat soak is likely at or near 295-300rwph.

Maybe that's why it seems there are more Turbo cars being built recently.


The biggest issue is and always will be IAT's with the CTSC design, you may get to 370-380 whp on a dyno but put the car on a track by lap 3 you will end up making 320-330 whp after it heat soaks and the ECU pulls timing. On the street you get to play a little longer but a 1-2-3 gear pull will put the IAT's in the 190-210 degree range and the car will just pull timing and add fuel and you will loose power.

kookoo4nsx said:

Wow, I had no idea that you could loose 50hp in just a few laps. I guess the advantage of the turbo is once the air is compressed, it has 5-6ft of piping with which to cool off vs the S/C which sits on top of a hot block.

I guess that heat also plagues low boost s/c's so using your math, you loose 50hp with a high boost, a low boost CTSC with heat soak is likely at or near 295-300rwph.

Maybe that's why it seems there are more Turbo cars being built recently.


The biggest issue is and always will be IAT's with the CTSC design, you may get to 370-380 whp on a dyno but put the car on a track by lap 3 you will end up making 320-330 whp after it heat soaks and the ECU pulls timing. On the street you get to play a little longer but a 1-2-3 gear pull will put the IAT's in the 190-210 degree range and the car will just pull timing and add fuel and you will loose power.

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Both SC and Turbo design have been around forever so i'll leave that pro/con discussion to the engineers. Both will have high IATs if you don't find a way to cool it with meth and/or an intercooler. The 5-6ft of piping in your turbo won't mean much if there's no intercooler in between somewhere. One could argue all that piping required to fit a Turbo is a con.

While we could argue the merits of why a blower is better than a snail the main pro I see with the CTSC, particularly for the NSX, is the very well engineered hardware (at least on my Autorotor) and the CARB certification (which some of you could care less about). If Comptech designed a twin turbo kit i'd be all over it but i'm almost certain they could not get that CARB approved for various reasons, nor could they make the packaging as stock-like or keep the costs reasonable. On street cars, likely their primary market from the get go, I much prefer the usability of the CTSC.

The reason you lose power when a CTSC heatsoaks is because, on a stock CTSC system, once the ECU sees a high IAT condition it pulls timing and runs the car rich, therefore hp is lost. If you solve this with some kind of cooling solution then you're golden. This is why many of us are ditching the stock Comptech fueling and using an EMS or F/IC and installing an aftercooler and/or spraying water/meth. All the turbo kits I see for the NSX already come with an intercooler. It's a testament to the CTSC kit to be as reliable as it is w/o cooling or maybe it's a testament to the NSX engine.

I don't think a turbo is better than a supercharger per say. They each have their unique issues especially when choosing a kit for the NSX. If I get really serious about tracking my NSX (i'm not) i'll consider a TT kit. Otherwise, for all other types of driving, even canyons, I actually prefer the SC. Different strokes for different folks?

If Comptech designed a twin turbo kit I'd be all over it but I'm almost certain they could not get that CARB approved for various reasons, nor could they make the packaging as stock-like or keep the costs reasonable.

^^^^This

My Aerochargers were designed to be cat-back and to pass California Emissions but the cost to get anything CARB approved is over $50k and if you are not turning enough merchandise, why send in the app for approval? I'm pretty sure that with F/IC and a good tuner the numbers would be low enough to pass a CA smog with the sniffer. But once they plug into your OBDII.....toast.

That is why I kept all my OEM intake and exhaust so that next year, I can get through the bi-annual smog certification. Unless I can devise something else

I wouldnt run larger than a 550 injector with this kit. Its not needed and since the FIC is piggyback the larger then injector the further you are going from the stock map. Low boost these kits make 365whp and even if he puts the high boost pulley its more than enough injector. My AEM water/meth kit has really helped my car in keeping the power stable. My IAT have dropped 20-25 degrees. You really notice the benefit of the water injection when running the car hard. The car doesnt lose power through the gears. I have taken my car up to 150mph from 60 several times and the IAT has not gone above 155 degrees. In the middle of summer i would expect 175.

What is a ballpark on the minimum requirment for this setup? Ideally i would like to find some that can provide enough fuel at below 45-50psi. if i had a baseline then it would be easier to know what will work.


Mike

kookoo4nsx said:

Wow, I had no idea that you could loose 50hp in just a few laps. I guess the advantage of the turbo is once the air is compressed, it has 5-6ft of piping with which to cool off vs the S/C which sits on top of a hot block.

I guess that heat also plagues low boost s/c's so using your math, you loose 50hp with a high boost, a low boost CTSC with heat soak is likely at or near 295-300rwph.

Maybe that's why it seems there are more Turbo cars being built recently.

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The advantage of the turbo or centrifical blowers is the placement of the compressor allows for an easier placement of an intercooler or meth. The CTSC design with the blower mounted directly on top of the intake runners leaves very little room for any type of intercooler and in most cases forces the use of meth/water to happen prior to the blowers inlet reducing its efficiency by forcing it to cool the blowers rotors as well as the charge air instead of just the charge air.

There are other losses when considering a twin screw blower to take into consideration like the parasitic loss of turning the blower itself. That is one reason a turbo can make 400whp on 6lbs of boost and a SC will need around 9lbs to make the same wheel horse power. The pumping forces of the blower require HP to turn and the Turbo while a restriction in the exhaust is using almost free energy from the exhaust to turn, in reality the cars are making almost the same power on the same boost it is just that more is being consumed by the blower than the turbo and does not make it to the tires.

Dave

OK, i used one of the calculators and making various changes my requirements should be anywhere from 424cc to 521cc between 40psi- 43.5psi. The 424 would be at a minimum hp and the 521 would be at a higher hp then i will actually achieve. So to me, as long as i cover the 521cc i'm good.

RDX 500-510cc @ 55-58psi
Have to rule these out because of the high pressure requirement.

ID 725 610cc @ 40psi and 725cc @ 43.5psi
I belive these will be too large for my setup.

RC SL9-0550 550cc @ 43.4psi
These seem to be my only option. Wish i knew what cc they are at around 40psi.


Mike

comtec said:

OK, i used one of the calculators and making various changes my requirements should be anywhere from 424cc to 521cc between 40psi- 43.5psi. The 424 would be at a minimum hp and the 521 would be at a higher hp then i will actually achieve. So to me, as long as i cover the 521cc i'm good.

RDX 500-510cc @ 55-58psi
Have to rule these out because of the high pressure requirement.

ID 725 610cc @ 40psi and 725cc @ 43.5psi
I belive these will be too large for my setup.

RC SL9-0550 550cc @ 43.4psi
These seem to be my only option. Wish i knew what cc they are at around 40psi.


Mike

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If you stay or plan to stay under 400whp the 410CC rdx will work but will require the higher fuel pressure to be operating at their best, 440cc, 550cc, 725cc, even 750cc will all work. The F/IC will be able to deal with these injector sizes and the higher fuel pressures if you decide to run the RDX 410cc injectors.

The smaller the injector the less the injector offset will be in the F/IC. In almost every case the smaller the offset the better.

Dave

DDozier said:

If you stay or plan to stay under 400whp the 410CC rdx will work but will require the higher fuel pressure to be operating at their best, 440cc, 550cc, 725cc, even 750cc will all work. The F/IC will be able to deal with these injector sizes and the higher fuel pressures if you decide to run the RDX 410cc injectors.

The smaller the injector the less the injector offset will be in the F/IC. In almost every case the smaller the offset the better.

Dave

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How much of a difference in the offset would you expect between the 440-550? Enough to really matter?

Thanks
Mike

Mike - out of curiosity why are you against running at highr pressures?

Not really against it, more that i can't see a reason to raise the fuel pressure when i can use larger injectors at the oem pressure. Having to raise the pressure above oem is basicly what the comptech bandaid does, isn't it?

If i could see a benefit from it, i would be all over it :wink:


Mike

In the case of the RDX, the assumption is higher pressure promotes better atomization.

RYU said:

In the case of the RDX, the assumption is higher pressure promotes better atomization.

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I remember someone once saying "assumption is the mother of all f-ups". Think it was a movie :biggrin:


Wouldn't pumping that 410cc up to 510cc max out the injector? Is it good to push a small injector that hard? For some reason they are all rated at the 43.5psi at their given cc it seems.


Mike

Under Siege 2 and Heartbreak Ridge.

comtec said:

I remember someone once saying "assumption is the mother of all f-ups". Think it was a movie :biggrin:



Mike

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kookoo4nsx said:

Under Siege 2 and Heartbreak Ridge.

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Yep, seen both of them. Makes sense when you think about it.

Mike

comtec said:

I remember someone once saying "assumption is the mother of all f-ups". Think it was a movie :biggrin:


Wouldn't pumping that 410cc up to 510cc max out the injector? Is it good to push a small injector that hard? For some reason they are all rated at the 43.5psi at their given cc it seems.


Mike

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The static fuel pressure at the rail is not really that big of a deal to change. The issue you are speaking of is with CT's use of a RRFPR and a Boost-a-pump. In the case of the CT fuel system for the HiBoost you would see static fuel pressures of 45-50psi then uder boost the fuel pressure could spike to 100-110psi. This spike in fuel pressure is the issue as most of the old injectors were designed for 40-50psi rail pressure. The more modern injectors are running 58-65psi as the normal rail pressure and they do so to allow for finer droplets as the fuel leaves the injector. The other thing to keep in mind is that fuel pumps flow much less fuel at higher pressures. On a Walbro I would not want my peak pressure to be above 72psi but anything below that and the pump will not care.

If you start with a rail pressure of 58psi and run 10lbs of boost with a 1:1 regulator you will not be over 68psi peaks and all will be well so running the RDX at their recommended fuel pressure is not an issue. Or you can run a 550cc at the stock fuel levels and the flow of fuel will be very close in the end. Some will argue the RDX at higher fule pressure will make more power and be more fuel efficient based on the modern injector design vs the old school design of teh 550cc.

comtec said:

How much of a difference in the offset would you expect between the 440-550? Enough to really matter?

Thanks
Mike

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The total amount of offset does not matter much as long as it is within range of the F/IC adjustments, the benefit of a smaller offset is the F/IC does everything by percentages, so if your offset is 40% and you make a 1% adjustment then the real effect is 0.004 change, if your total offset is 80% and you make a 1% adjustment then the real effect is 0.008 change. Both the F/IC and the ECU calculate and make changes to fuel trims in percentages so the closer you make the new injector to the old injector size the more resolution you have in your adjustments.

I have not tested this yet but it may actually be better to run a smaller injector and a higher fuel pressure to give you a smaller offset based on flow. Just do not know yet as I have not played with fuel pressure changes yet.

Dave

As i said, i'm a old carb man so let me see if i understand this pressure thing.

So, The FI/C will adjust the FPR for the amount of fuel pressure required? If so then is this done by varying the vacuum to the FPR or by varying the voltage to something?


Mike


Took me too long to post so i didn't see yours.

Valuable information Dave, Thanks so much!

comtec said:

As i said, i'm a old carb man so let me see if i understand this pressure thing.

So, The FI/C will adjust the FPR for the amount of fuel pressure required? If so then is this done by varying the vacuum to the FPR or by varying the voltage to something?


Mike

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No the F/IC only adjusts injector pulse width and in effect adjust the amount of fuel delivered. The fuel pressure is adjusted by the FPR and the VAC refference. So if you raise the base fuel with the FPR you will increase the offset in the F/IC and the pulse width will be shorter and you will spray less fuel. If you lower fuel pressure the opposite happens. The key is consistent fuel pressures, that is why we want to get rid of the old CT HiBoost RRFPR as the only thing consistent about its fuel pressure delivery is its lowest and highest pressure everything else is a mystery and very hard to tune around. The 1:1 FPR gives us a linear increase in pressure and can be calculated into the injector change and was calculated into the OEM ECU as the OEM FPR is a 1:1 regulator.

You are most likely splitting hairs here at the power level you are the injectors we have talked about here will all work and present no issue for the F/IC or the rest of your fuel system. Pick one and install them you will be fine with whatever you choose. If you already have something that came with your kit then use those as long as they are at least 440cc's. Spend your money on dyno time and your tune it matters much more than the difference between a 440 or 550cc injectors. If I had to buy something and could not reuse what I had I would buy the 550cc injectors, they are good to 500whp and will have a higher resale if I decided to part out my kit at a later date.

Dave

Awesome Dave, Thanks.
Going with the 550, moving on.


I'm good on the dyno cause they are going to get it for the day.


I hear people taking about base maps. Is that something that will help out the tuner? I'm not sure how much experience he has with the NSX.


Mike

comtec said:

Awesome Dave, Thanks.
Going with the 550, moving on.


I'm good on the dyno cause they are going to get it for the day.


I hear people taking about base maps. Is that something that will help out the tuner? I'm not sure how much experience he has with the NSX.


Mike

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He needs to know the F/IC more than the NSX, send me a PM with your email and I will get you and your tuner some info to get you started. There is no real base map with an F/IC or at least one that your tuner can not make in 5 min. or less.

Dave

DDozier said:

He needs to know the F/IC more than the NSX, send me a PM with your email and I will get you and your tuner some info to get you started. There is no real base map with an F/IC or at least one that your tuner can not make in 5 min. or less.

Dave

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Dave, your the best


Mike




On a side note,

I bought that bumble bee blower :biggrin: . Anyone know the best way to remove powder coat?

You bought that? Good deal!

junior40er said:

You bought that? Good deal!

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Yep, now just got to get rid of the yellow :redface:


Mike