Fuel Injector Blueprinting

DanO · 27 December 2001

Hello all

A couple weeks ago I sent all 6 of my fuel injectors to RC Engineering www.rceng.com for cleaning and flow testing. Here are the results:

Flow testing was done at 50, 60, 70, 80, 90 and 100psi. As you can see, the injectors flowed pretty much to formula, which is: SQRT(new psi/old psi) * old flow rate. Here’s a table:

I picked a baseline flow rate of 244cc at 43psi.

PSI Actual Flow Formula Flow Difference
43 244 244 0
50 266 263 +3*
60 298 288 +10
70 319 311 +8
80 347 333 +14
90 361 353 +8
100 375 372 +3

*From what I can tell, the stock NSX rail pressure is 50psi.

It’s interesting to note that two of my injectors tested “poor” and one “fair” before cleaning. My NSX is a ’92 with about 40,000 miles.

RC was really easy to work with and they processed my injectors extremely quickly. Total bill including shipping was $152.00.

I hope to do a DIY write-up (within the next few months) on how to remove/install the injectors complete with all the part#s one would need for new seals and o-rings and crush washers and post it on my diy site at www.danoland.com/nsxgarage.

DanO

[This message has been edited by DanO (edited 27 December 2001).]

ScienceofSpeed · 27 December 2001

cool post Dano... Definitely interested in the DIY.

-- C

------------------

DanO · 27 December 2001

Originally posted by ScienceofSpeed:
cool post Dano... Definitely interested in the DIY.
-- C

I think it would be cool for an aftermarket vendor to sell a kit that included all the new parts, instructions and flow datasheet for an injector overhaul (core return type thing). It's my bet that anyone going the boosted route would like to know that thir injectors are aok first.

DanO

Jason Weaver · 27 December 2001

DanO, Excellent post. That is cheap insurance for like you said someone who is about to install any type of forced induction. I am going to send mine off for sure, with the NOS and 75k miles I'm sure it's time for a cleaning. The DIY article would be great!

------------------
Jason

[This message has been edited by Jason Weaver (edited 27 December 2001).]

NSXLNT · 27 December 2001

Have you re-installed and taken for a ride yet? I'm wondering if you noticed any appreciable performance improvements. Do you think regular use of an in-fuel injector cleaner, such as Techron, would negate the need to do what you had done? Thanks for the post.

sjs · 28 December 2001

Thanks DanO!!

This is now on my do-list.

As I read it, at 43psi the stock injectors support only 224hp at 80% duty cycle. How much above 43 does the stock system go based on various sensors during high demand?

4g62bt2c30a · 28 December 2001

Originally posted by sjs:
Thanks DanO!!

This is now on my do-list.

As I read it, at 43psi the stock injectors support only 224hp at 80% duty cycle. How much above 43 does the stock system go based on various sensors during high demand?

I see 52 psi at WOT.

DanO · 28 December 2001

Originally posted by sjs:
Thanks DanO!!

This is now on my do-list.

As I read it, at 43psi the stock injectors support only 224hp at 80% duty cycle. How much above 43 does the stock system go based on various sensors during high demand?

I think the service manual says that rail pressure is around 50psi.

DanO · 28 December 2001

Originally posted by NSXLNT:
Have you re-installed and taken for a ride yet? I'm wondering if you noticed any appreciable performance improvements. Do you think regular use of an in-fuel injector cleaner, such as Techron, would negate the need to do what you had done? Thanks for the post.

No, i have not put them back in yet. There's a couple inches of snow on the ground right now so i won't be able to take it out for a bit.

I'm not expecting any noticeable difference in performance.

DanO

BryanZublin · 29 December 2001

Originally posted by sjs:
(snip)
As I read it, at 43psi the stock injectors support only 224hp at 80% duty cycle. How much above 43 does the stock system go based on various sensors during high demand?

Page 11-88, "Fuel Pressure" from the 1992 service manual lists the acceptable fuel pressure as 46 to 53 psi with the vacuum line from the pressure regulator disconnected (basically the same condition as wide open throttle). Assuming a baseline of 50 psi, this range will result in a flow rate variation of +3% / -4%.

Using the low end of 46 psi and the low measured flow rate of 244 cc/min at 43.5 psi, the new flow rate is 251 cc/min.

Using 251 cc/min, 80% max duty cycle and 0.5 BSFC, the supported horsepower calculates to 38.2 hp per injector, or 229.5 hp for our 6 cylinder. This is using the formulas on the RC Engineering web page.

I would guess that the discrepancy in the calculation vs. the actual hp rating of the NSX 3L V6 (270 hp) is because the NSX engine is more efficient than 0.5 BSFC, and perhaps the actual max injector duty cycle is greater than the "accepted industry standard" of 80%.

Using 0.45 for BSFC and 90% for the duty cycle, the supported hp jumps to 287 hp. Perhaps some day soon I will measure the injector duty cycle at full throttle and peak hp RPM.

Bryan Zublin

------------------
Zublin Engineering
http://www.zublin.com

Jason Weaver · 29 December 2001

Bryan, Wouldn't it be possible to measure injector duty cycle etc. on one of the stand along engine management systems? I know these are very pricey, and to have one on a mostly stock car would probably be a little overkill. However, I have seen up close the software and the Speed Pro system and it is absolutely amazing. Aren't some of the "basic" Haltech systems under a grand? I have been told there is some hp to be gained by fuel/timing tuning on the NSX. Just my 02.

------------------
Jason

[This message has been edited by Jason Weaver (edited 29 December 2001).]

hejo · 29 December 2001

Great stuff DanO! This fills in a few more blanks for us around the BB. I think Bryan is right also. When I did my calcs I figured the bsfc to be around .43~.44 which would lower the duty cycle just a touch to get 270 hp. Jason I know there's hp to be gained through better fuel/timing as that's what the superchips are doing.

BryanZublin · 30 December 2001

Jason,
Yes, having an aftermarket (stand alone) ECU would give you complete control over the fuel ratios and ignition timing. For a serious race only application, this is probably the preferred approach. One of the cheapest (and easy to use) appears to be the Simple Digital Systems unit.

However, you will loose some of the "street" features of the stock ECU such as traction control (the TCS computer recieves inputs from the ECU). Another issue is tuning - you will have to create fuel maps for all operating conditions which is time consuming and may result in worse driveability compared to the stock ECU settings. Then there are emissions testing issues (in CA) and CARB exemption approvals that would be more difficult. Not to mention modifications to the wiring harness, etc.

I think the basic approach that many tuners take is to keep as much of the stock ECU as possible since its driveability and reliability have been perfected by Honda. Then, adjust fuel and timing only when needed (during boost). The cost of an add on box should be less than half the cost of an aftermarket ECU.

An even better solution would be to add new fuel map entries in the stock chip for the boost condition which would be dirt cheap on a recurring basis and retain all benefits of the stock ECU. This is what the Hondata system does (http://www.hondata.com/), but it appears not to be available for the NSX ECU.

Bryan Zublin

------------------
Zublin Engineering
http://www.zublin.com

hejo · 31 December 2001

A little off topic but thought I'd ask here anyway... What size injectors are on the S2000?

BryanZublin · 10 January 2002

Extrapolating from the NSX's 270 HP to the S2000s 240 HP, an estimate for the S2000 injectors:

(240 HP / 270 HP) * (6 cly / 4 cyl) * (240 cc/min)
= (0.89)*(1.5)*(240 cc/min) = 320 cc/min

Bryan Zublin

nsx1164 · 10 January 2002

Originally posted by BryanZublin:
An even better solution would be to add new fuel map entries in the stock chip for the boost condition which would be dirt cheap on a recurring basis and retain all benefits of the stock ECU. This is what the Hondata system does (http://www.hondata.com/), but it appears not to be available for the NSX ECU.

One of my boost-happy techs in S Florida tells me that Hondata has an application for the early model NSX (non-OBD II). Tells me it works real well with TT setups.

BryanZublin · 6 February 2002

Originally posted by nsx1164:
"One of my boost-happy techs in S Florida tells me that Hondata has an application for the early model NSX (non-OBD II). Tells me it works real well with TT setups."

I just called Hondata and the guy on the phone said that they do not support the NSX. I even called back to mention that the NSX is listed on their web page, but he said that the web page is in error. He mentioned that their is no demand for the NSX application (no surprise).

Can you confirm with your Florida tech that it is in fact the Hondata system being used?

Bryan Zublin

------------------
Zublin Engineering
http://www.zublin.com

sjs · 6 February 2002

Originally posted by BryanZublin:
I just called Hondata and the guy on the phone said that they do not support the NSX. I even called back to mention that the NSX is listed on their web page, but he said that the web page is in error.

That would explain why they never answer my emails. Lazy SOBs.

4g62bt2c30a · 6 February 2002

Originally posted by BryanZublin:
Originally posted by nsx1164:
"One of my boost-happy techs in S Florida tells me that Hondata has an application for the early model NSX (non-OBD II). Tells me it works real well with TT setups."

I just called Hondata and the guy on the phone said that they do not support the NSX. I even called back to mention that the NSX is listed on their web page, but he said that the web page is in error. He mentioned that their is no demand for the NSX application (no surprise).

Can you confirm with your Florida tech that it is in fact the Hondata system being used?

Bryan Zublin

Hondata is in beta on the NSX program... There taking there time...

BryanZublin · 7 February 2002

Originally posted by 4g62bt2c30a:
Hondata is in beta on the NSX program... There taking there time...

So do you know the scheduled release date? Does "beta" mean that the product is installed on one or more NSX's that are being driven on the road?

I got the impression that they were not even considering developing the product for the NSX since the market is so small.

Bryan Zublin

------------------
Zublin Engineering http://www.zublin.com

[This message has been edited by BryanZublin (edited 06 February 2002).]

nsx1164 · 7 February 2002

Originally posted by BryanZublin:
I just called Hondata and the guy on the phone said that they do not support the NSX.

I even called back to mention that the NSX is listed on their web page, but he said that the web page is in error. He mentioned that their is no demand for the NSX application (no surprise).

Can you confirm with your Florida tech that it is in fact the Hondata system being used?

My tech is named Giovanni, and he's at SABAL CHASE (1-800-329-2427). I think Enrique (Panama NSXr) has dealt with these folks before. He mentioned an OBD-I only Hondata application (1991-1994).

4g62bt2c30a · 7 February 2002

Originally posted by BryanZublin:
So do you know the scheduled release date? Does "beta" mean that the product is installed on one or more NSX's that are being driven on the road?

I got the impression that they were not even considering developing the product for the NSX since the market is so small.

Bryan Zublin

When I spoke with them last week they said they had a couple cars they were testing programs on one was a comptech supercharged car... They had said the base program for forced induction would allow of 440 cc injectors to be run at factory psi... He said that they we still a ways away but might have the program nailed down in the next couple of weeks... I will talk to them again today and see what more info I can get.. I know first hand how amazing this product would be for the NSX community and I hope they follow through...

Corey

sak · 26 February 2002

Great post here. I'm looking for NSX injectors, but I don't know how to read the chart provided. Can anyone tell me what size the NSX injectors are?

sjs · 27 February 2002

Originally posted by 4g62bt2c30a:
When I spoke with them last week they said they had a couple cars they were testing programs on one was a comptech supercharged car... They had said the base program for forced induction would allow of 440 cc injectors to be run at factory psi... He said that they we still a ways away but might have the program nailed down in the next couple of weeks... I will talk to them again today and see what more info I can get.. I know first hand how amazing this product would be for the NSX community and I hope they follow through...

Corey

Any news?

BryanZublin · 27 February 2002

Originally posted by sak:
Great post here. I'm looking for NSX injectors, but I don't know how to read the chart provided. Can anyone tell me what size the NSX injectors are?

The injectors that DanO tested are from his stock NSX (pre-1997). I believe that the nominal flow rate for these stock injectors is 240 cc/min.

Bryan Zublin

------------------
Zublin Engineering
http://www.zublin.com

Fuel Injector Blueprinting

Similar threads