Does anyone want an overview UNDERSTANDING YOUR FUEL SYSTEM?

[BadCarma]

Hey guys, does anyone want an indepth explanation of our fuel system? with all these new SC installs it seems alot of guys are concerned about proper fuel delivery.
I would cover the fuel pump, the fuel lines,the regulator and the injectors.
then I would break it down in sub sections pertaining to each portion of a properly tuned fuel system to meet the demands of N20 ,SUPERCHARGER OR TURBO. I am beat and dont want to do it tonight but feel it is needed with so many new guys gone FI. let me know if this is something you want to see.if not oh well.
Best Regards David
PS this is in the interest of obtaining a proper A/F ratio for your new SC car

 

[D'Ecosse]

David, I'm confident this would be a very worthwhile addition to the knowledge base!

Some won't realize how much they will have appreciated it until after you lay it out, so go for it my friend! <!--StartFragment -->

 

[stevenlee]

David,
Please share your knowledge with us.

 

[DutchBlackNsx]

Sure David, sounds interesting, maybe even more if you also include differences with other fuel systems such as the low pressure ones and its pro's and con's.

I'm still suprised by the amount off peeps who put a turbo/sc on there car without understanding the importancy of the fuel delivery system.

 

[Bob Kenney]

David,
This will be great topic, any knowledge shared/gained is worth the effort, please layout the overview.

I am specifically interested in discussing:
A/F ratios required at what RPM and how the injectors work to achieve this ratio.
Size of the injectors in relationship to displacement and boost.
Fuel pump types/pressure and what the acceptable range of pressure is for the injectors.
Fuel regulators/types and how they operate and are controlled, what happens to the excess fuel being pumped.
Compression ratios verses A/F ratios, A/F temperatures and boost; how are they related.
How gasoline Octane can effect what A/F ratios are acceptable.
How engine timing and RPM is related to all the above.

I know it is a lot to ask; but as long as we are at it we might as well try achieve a comprehensive understanding of what is happening in the engine and how that is affected by Boost.

Thanks

Bob

 

[splitz]

Any new knowlege about this car is greatly appreciated. Would this cover the basics of tuning and mapping?

 

[BadCarma]

David,
This will be great topic, any knowledge shared/gained is worth the effort, please layout the overview.

I am specifically interested in discussing:
A/F ratios required at what RPM and how the injectors work to achieve this ratio.
Size of the injectors in relationship to displacement and boost.
Fuel pump types/pressure and what the acceptable range of pressure is for the injectors.
Fuel regulators/types and how they operate and are controlled, what happens to the excess fuel being pumped.
Compression ratios verses A/F ratios, A/F temperatures and boost; how are they related.
How gasoline Octane can effect what A/F ratios are acceptable.
How engine timing and RPM is related to all the above.

I know it is a lot to ask; but as long as we are at it we might as well try achieve a comprehensive understanding of what is happening in the engine and how that is affected by Boost.

Thanks

Bob

Bob, piece of cake! that is a very good spectrum pertaining to what I want to discuss.we will get into ALL of that.
Best Regards David
PS. You seem to have thought about this before as you touched on all the major points to discuss.BTW You ask above for me to layout the overview...I think you did a fine job with it! if we cover those points you want addressed it will lead to some offshoot questions but is a very suitable overview AFAIAC

 

[Bob Kenney]

"When the student is ready the teacher will appear."

Thanks David, I am looking forward to these discussions to clarify the "Balance" that must exist between these dynamic parameters.

Bob

 

[DDozier]

"When the student is ready the teacher will appear."

Thanks David, I am looking forward to these discussions to clarify the "Balance" that must exist between these dynamic parameters.

Bob

I too am ready to learn Grasshopper.

Dave

 

[BadCarma]

hey guys, I am not going to get into it tonight. I have been engrossed in one of my cars motor swap....a swap that would piss off some folks,I am wanting to put a nissan JDM bluebird motor into my crx.the motor is a transverse sr20det like used in the jdm silvia. I think I can pull 350 out of it at the wheels anything more I will need to do surgery.
this all fits with the nsx fuel delivery topics as I have been deluged with info on designing a proper fuel system to support the frankenbeast. I have learned alot of subtle issues I was not aware of and will share away but I really need to finish this baby up as parts are disapearing...were I dont know.they have been available for months and when I finally get down to business the parts I chose or want are suddenly gone. sob sob sob. I will lay out the setup tommorrow for sure, BTW you dont need me to start.there are some bright boys on here.

best regards david

ps sorry for flaking but I want my hybrid honda that will eat all that dares step to it.
oh hey I found an awesome link that covers how to:
leakdown test
compression test
verify signs of detonation
lots of subjects of interest to many on the board,I will post that link also

 

[jmp]

Fuel System 101 would be greatly appreciated. Curious to know your thoughts on cavitation of the fuel impeller; fuel pressure vs. fuel volume/unit of time, and injector pulsing.

Thanks grahs-hahpa!

 

[HotRod]

This would be greatly appreciated. Thanks for your efforts..

Rod

 

[splitz]

Oh, and how fuel managment systmes play into the whole game would be great too!

 

[Bob Kenney]

Fuel System 101 would be greatly appreciated. Curious to know your thoughts on cavitation of the fuel impeller; fuel pressure vs. fuel volume/unit of time, and injector pulsing.

Thanks grahs-hahpa!

jmp,
BadCarma sounded a bit tied-up with his latest project and encourage us to get started without him. Your question concerning fuel pump cavitation caught my interest.
Do you believe that you have had this occur?
If yes; under what conditions? [highspeed cornrering, near empty tank]
What were the systems?

Bob

 

[jmp]

Overburdening my fuel pump by zapping it with extra voltage to take an impleller designed to run at 50 psi and have it run at 90. The dyno results interpreted by two people whom I trust suggest cavitation (A/F ratio that goes up and down throughout the rpm range until the upper end at which point it cannot keep up and A/F remains wel above 12 causing us to not complete the testing). New CTSC. Trying to sole the A/F dilemma.

 

[Bob Kenney]

Overburdening my fuel pump by zapping it with extra voltage to take an impleller designed to run at 50 psi and have it run at 90. The dyno results interpreted by two people whom I trust suggest cavitation (A/F ratio that goes up and down throughout the rpm range until the upper end at which point it cannot keep up and A/F remains wel above 12 causing us to not complete the testing). New CTSC. Trying to sole the A/F dilemma.

It is my understanding that CT used the increased voltage to the stock fuel pump to increase the fuel pressure so the stock [240 cc injectors {app}] would be capable of suppling enough fuel for the increased air flow from the SC. The system has worked well in a lot of applications for years but as with most things I feel it can be improved upon.
I seem to have a problem with running excessively rich at times. Tail pipes are very carboned when driving around town; on the track at high RPM and high loads the tail pipes show Little sign of deposits and what they do show is light tan indicating complete combustion.
I have decided to order an AEM ECM to deal with the problem. I will also change to a Walbro fuel pump and AEM fuel regulator at the time of the AEM ECM install. I am toying with the idea of purchasing the "9 lb" boost kit from SOS given it comes with the Walbro pump, AEM fuel regulator and larger injectors in addition to the new pulley and drive belt.
I am wondering if just the addition of a Walbro high pressure pump would make a positive difference; I believe this change would require a different fuel regulator [AEM] to work effectively. Do you have any thoughts on this proposed set-up?

Bob

 

[BadCarma]

jmp,
BadCarma sounded a bit tied-up with his latest project and encourage us to get started without him. Your question concerning fuel pump cavitation caught my interest.
Do you believe that you have had this occur?
If yes; under what conditions? [highspeed cornrering, near empty tank]
What were the systems?

Bob

Bob, thanks for getting the ball rolling.that was exactly what I wanted and it is the swap project holding me up with other projects except a n20 kit that needs to go to Cali (James...get ready bro!) its coming!

I have been dropping in and checking this thread and jmp and others are touching on valid concerns about their fuel systems and effect on the SC performance,AF TUNING so on. I do have alot to say about this but one thing I do NOT want to see is any bashing of Comptech or any vendor in the discussion.we want a rational exchange of theory and application and keep it free from emotional ties to problems that can be ironed out. if it happens to be a comptech SC on your car and fuel delivery is the issue we are merely looking at alternative ways to accomplish the goal then was provided at install.
JMP, your trusted sources are correct in their assessment.I will explain what I came up with in terms of duty cycles on the injectors and the whole system that has been used for fuel delivery the comptech way. the good news is it can be improved on just stay light on the peddle until you get a reliable AF across the band
Best Regards David
PS. would you guys want to use the chat feature of prime one night to toss info back and forth. hell invite comptech if they want to come as a guest speaker....that could go sideways but what about it.anyone up for a chat one night this week? the chat would be on fuel system only!

 

[BadCarma]

It is my understanding that CT used the increased voltage to the stock fuel pump to increase the fuel pressure so the stock [240 cc injectors {app}] would be capable of suppling enough fuel for the increased air flow from the SC. The system has worked well in a lot of applications for years but as with most things I feel it can be improved upon.
I seem to have a problem with running excessively rich at times. Tail pipes are very carboned when driving around town; on the track at high RPM and high loads the tail pipes show Little sign of deposits and what they do show is light tan indicating complete combustion.
I have decided to order an AEM ECM to deal with the problem. I will also change to a Walbro fuel pump and AEM fuel regulator at the time of the AEM ECM install. I am toying with the idea of purchasing the "9 lb" boost kit from SOS given it comes with the Walbro pump, AEM fuel regulator and larger injectors in addition to the new pulley and drive belt.
I am wondering if just the addition of a Walbro high pressure pump would make a positive difference; I believe this change would require a different fuel regulator [AEM] to work effectively. Do you have any thoughts on this proposed set-up?

Bob

Bob, what do you think your injector duty cycle is at under full boost,I say in the 90 pecentile...high in the 90's. I think we can bring it down,others have suggested that the 240 cc can handle it.I do not atleast in the long term and I think they may in some instances be stepping which is not good. thoughts?

 

[jmp]

First of all, I agree with the comment about not bashing CT. While I have had issues during the install/tuning phase, I still respect CT's products, R&D and overall success in deliverying good value to us. I am only looking to get my car tuned properly and overcoming a few challenges so that I can enjoy their product.

By Monday close of business, I will know if the combination of the Apexi piggyback fuel "computer" combined with the 440 injectors took care of the problem. If it does not then we need to go to a hi-flow fuel pump, which is fine with me, but ... I understand that I will encounter some electronics challenges with zapping the pump (the CT is setup to send a double-zap to the oem pump to double fuel pressure and I am not sure how your bring that voltage down short of an AEM), and I do not then wish to spend another $1500 for an AEM and then lose oem starting and driveability.

I have my fingers crossed for Monday. Thanks to all.

 

[RON98]

you dont need extra fuel with a SC/TC setup.

The extra air will do all the work + better gas milage too. Duh!! :biggrin:

 

[Bob Kenney]

Bob, what do you think your injector duty cycle is at under full boost,I say in the 90 pecentile...high in the 90's. I think we can bring it down,others have suggested that the 240 cc can handle it.I do not atleast in the long term and I think they may in some instances be stepping which is not good. thoughts?

David,
I hope your swap went/is going well.
I do believe the fuel pressure, fuel pump, injector relationship on the Whipple CTSC can be improved. The duty cycle of the injectors is maxed, the fuel pump is pushed beyond its designed voltage and the pressure in the fuel supply system is quite high. Going with just larger injectors and a higher volume fuel pump may work but does not seem refined enough to be efficient across the whole RPM range. How would you handle the problem? AEM?

Bob

 

[Bob Kenney]

Quote; BadCarma
PS. would you guys want to use the chat feature of prime one night to toss info back and forth. hell invite comptech if they want to come as a guest speaker....that could go sideways but what about it.anyone up for a chat one night this week? the chat would be on fuel system only![/QUOTE]

David,
Great idea; an open flow of ideas and information might be just what is needed to define the concerns/problems some of us are facing and explore solutions that may not have been considered. Count me in; but I leave on Friday for Road America for the weekend.:biggrin:

 

[12AMNSX]

I think the chat idea is good with the exception that it won't provide a written trail of what is discussed like you would accomplish via a thread.

 

[Bob Kenney]

I think the chat idea is good with the exception that it won't provide a written trail of what is discussed like you would accomplish via a thread.

You make a very valid point; so lets get this disscussion going on this thread.
What are your needs, concerns, and desires concerning the fuel system on your NSX? :smile:

Bob

 

[Bob Kenney]

By Monday close of business, I will know if the combination of the Apexi piggyback fuel "computer" combined with the 440 injectors took care of the problem. If it does not then we need to go to a hi-flow fuel pump, which is fine with me, but ... I understand that I will encounter some electronics challenges with zapping the pump (the CT is setup to send a double-zap to the oem pump to double fuel pressure and I am not sure how your bring that voltage down short of an AEM), and I do not then wish to spend another $1500 for an AEM and then lose oem starting and driveability.

I have my fingers crossed for Monday. Thanks to all.

I also have had my fingers crossed for you all weekend hoping that you have found the solution. It is the end of the business day on Monday; I am anxious to know; how did your experiment turn out?

Bob