1g MAF / 450cc / 14b injector DC/pulsewidth poll

[gsx91boy]

Just curious what some of ya'll are hitting as far as duty cycle or pulsewidths go on the 14b/450s/1g maf and @what psi - I'm trying to decide if I have a problem area in my setup.

So please tell me your DC's / pulsewidths @6000rpm please (and preferably in a reasonable temperature range aka no outlyers like 30 deg weather or 110 deg weather )

thanks

-aaron

 

[kpt4321]

I don't have an exact number for you.

However, a 14b on a well set up car will max out 450's without much trouble.

I had a 14b, SMIC, 3" exhaust, pump gas, and I was set at about 16 psi. My injectors would go well over 100% duty cycle, up to around 110% or so.

That was with only the lower honeycomb removed, and the screw backed out a bit.

The car made decent power like that, it trapped around 100 mph consistiently with a 3200 pound race weight.


For reference, I'm still running the 14b, but now I have a FMIC and 620 cc/min injectors. I'm pushing them to duty cycles in the 70's, maybe even the 80's, I will have to look at my datalog. The AFR at WOT is about 11:1.

 

[gsx91boy]

I had a 14b, SMIC, 3" exhaust, pump gas, and I was set at about 16 psi. My injectors would go well over 100% duty cycle, up to around 110% or so.

Excellent, this is what I wanted to know, thank you.



-aaron

 

[ahains]

I had a 14b, SMIC, 3" exhaust, pump gas, and I was set at about 16 psi. My injectors would go well over 100% duty cycle, up to around 110% or so.
That was with only the lower honeycomb removed, and the screw backed out a bit.

Kyle, good info, thanks.
I assume this was with stock fuel pump & regulator, so also then stock fuel pressure?
Thanks,
Adrian

 

[gsx91boy]

I had a 14b, SMIC, 3" exhaust, pump gas, and I was set at about 16 psi. My injectors would go well over 100% duty cycle, up to around 110% or so.

Ok another question to go along with that - did you ever hit fuel cut with that set-up (just the honey-comb removed, no bypassing, no extreme MAF hacking)?

'M cutting at around 18psi in ~65 deg weather with that setup (~80deg IAT's) and just wondering if I stil have leaks or if thats normal.

-aaron

 

[burldude]

Mine started doing that at around 18 psi also so I went with an safc and a maft and 3" maf and Dejon intake pipe with all the extra vaccum tubes installed.

 

[kpt4321]

Kyle, good info, thanks.
I assume this was with stock fuel pump & regulator, so also then stock fuel pressure?
Thanks,
Adrian

Aftermarket fuel pump, it was a Walbro 190.

Keep in mind that the aftermarket (larger) fuel pump is probably more likely to be stock fuel pressure under boost, compared to a stock pump, at this fuel flow level.

 

[kpt4321]

Ok another question to go along with that - did you ever hit fuel cut with that set-up (just the honey-comb removed, no bypassing, no extreme MAF hacking)?

I think my car has fuel cut once in the whole time I have owned it, so no, I didn't have any problems with it.

'M cutting at around 18psi in ~65 deg weather with that setup (~80deg IAT's) and just wondering if I stil have leaks or if thats normal.

In terms of boost leaks: Don't wonder, know. If you're not positive, you need to pressure test the system. With a standard MAF (pre-turbo especially) boost leaks absolutely kil every performance and drivebility aspect of the car.

I would consider running less boost on that setup, if I were you. With the SMIC and a 14b, you'll probably find that you make the most power at more like 16 psi (this assumes pump gas, of course).

 

[kpt4321]

Mine started doing that at around 18 psi also so I went with an safc and a maft and 3" maf and Dejon intake pipe with all the extra vaccum tubes installed.

None of these modifications do anything, directly, to get rid of fuel cut. In fact, by themselves, they make it worse.

If you fixed it with these parts, it was because of the reduction in airflow signal to the ECU.

 

[burldude]

Exactly the maft has a built in fuel cut defense ,giving a little more threshold . I should have included inconjunction with afpr.

 

[kpt4321]

Don't use the MAFT's fuel cut defense. It's just an aiflow cap, which is never a good idea.

 

[logic]

However, a 14b on a well set up car will max out 450's without much trouble.

I had a 14b, SMIC, 3" exhaust, pump gas, and I was set at about 16 psi. My injectors would go well over 100% duty cycle, up to around 110% or so.

Just in case someone doesn't believe Kyle, I'll back this up with my own numbers: 6-bolt 1g, bone stock except for a 2g TB elbow, K&N intake, some unrelated drivetrain work, and 17psi on 93 octane. I logged 103% duty cycle by about 5000 RPM in a 3rd-gear highway pull two weekends ago (cool evening, maybe 65F ambient), and the injectors just sputtered between 100% and 103% for the rest of the RPM band after that. Airflow maxed out at a bit over 1600Hz. Pretty high knock counts came along with that (25-30 in the upper RPM range), along with the obvious pulled timing.

So, basically, a cool night and a K&N was really all I needed to max out the 450s.

 

[kpt4321]

Logic, what car is this on? It sounds like you are using a 1g logger, so I presume it's not your 2g....

Good data though. Just imagine what happens with the same setup but a full exhaust...

 

[logic]

Logic, what car is this on? It sounds like you are using a 1g logger, so I presume it's not your 2g....

Heh, no, that was logged using MMCd on our 6-bolt 1g. I really didn't expect that, given how little has been done to the car. The exact numbers (now that I'm at home and have the Palm handy) were 103.9% DC, with 1603.9Hz, with 15 degrees of timing advance and a 23 count of knock. Also, I made a (pretty significant) typo above: it was at just over 6000 RPM, not 5000, that I started seeing 100% or more DC.

Good data though. Just imagine what happens with the same setup but a full exhaust...

Soon. Very soon. The S-AFC, FMIC, and piping are on their way, and full exhaust is planned shortly. And...er...a set of bigger injectors.

 

[gsx91boy]

I finally got around to making it to my Dad's to use his compressor. Air was just RIPPING out of one of the couplers. TIP: don't try to make a silicone coupler that is too big work, it won't

My logs were resembling old ones of when my plug on the j-pipe nipple blew off, so I knew I had some bad leaks somewhere, they just weren't showing up with the bike pump test.

I recall hitting +100% no problem on my car in the past (only drive the car 4 months of the year so I can't always recall exact circumstances) and was barely hitting +100 with 18psi and turboback. My friends car would hit 110% consistently on 16-18psi, K&N, and a leaky flex, with those nice .86 o2's, so again I figured there were leaks somewhere.

Thanks for the responses, they motivated me to use the compressor

-aaron

 

[neuro]

Just curious what some of ya'll are hitting as far as duty cycle or pulsewidths go on the 14b/450s/1g maf and @what psi - I'm trying to decide if I have a problem area in my setup.

So please tell me your DC's / pulsewidths @6000rpm please (and preferably in a reasonable temperature range aka no outlyers like 30 deg weather or 110 deg weather )

thanks

-aaron

Since you asked, I logged this the other day on the way home from work.

Logged with mmcd

Ambient Temp. 85ºF
6062 RPM (Fourth gear)
Injector PW 18.17ms
Duty Cycle 91.4% (peaks at 93.7%@6281)
Hz 1603.9
Knock 0
O2V 0.83v
Somehow forgot to log timing that time

This is on a 1990 GSX with the following mods:

Walbro 190
Apexi N1 catback
Profec B-SpecII at 16lbs
K&N no aircan
everything else stock

 

[gsx91boy]

Thanks a lot for the help!

It sounds like you have some leaks too though, , or maybe a tired 14b. I was hitting 100% DC on 16psi with a HUGE leak I found.

-aaron

Since you asked, I logged this the other day on the way home from work.

Logged with mmcd

Ambient Temp. 85ºF
6062 RPM (Fourth gear)
Injector PW 18.17ms
Duty Cycle 91.4% (peaks at 93.7%@6281)
Hz 1603.9
Knock 0
O2V 0.83v
Somehow forgot to log timing that time

This is on a 1990 GSX with the following mods:

Walbro 190
Apexi N1 catback
Profec B-SpecII at 16lbs
K&N no aircan
everything else stock

 

[neuro]

Thanks a lot for the help!

It sounds like you have some leaks too though, , or maybe a tired 14b. I was hitting 100% DC on 16psi with a HUGE leak I found.

-aaron

I've been thinking that for a while, now. My performance is inconsistent and my gas mileage is horrible (< 20MPG on the highway) and my fuel trims are all over the place (82% on the low trim, 108% high). Sometimes I think I hear a whistling sound at high RPM's in second, but I could be imagining things. I don't think it's related to my boost controller install, it was a bit off before then.

Could be the 14b, too. It seems a bit louder when it's cold when it spools. Seems laggy compared to other reports of 14b spool times - I'm not getting full boost til around 3200 RPM. I'll have to build or borrow a leak tester to find out for sure and check the shaft play while I'm at it.

 

[gsx91boy]

3200 isn't that bad - a lot of people are full of shit when they say 18psi by 2800 on 14b.

However, any loud squeeling noise is usually a boost leak. Could even been your compressor housing o-ring. I'd leak test the intake to be sure. I know 90's show a lot lower voltage, and I'm pretty sure I've seen mid .7 o2s safely on 90's, making your .82's rich.

I bought some couplers that will fit snug today, so hopefully I'll have some updated logs where I'm leaning out and maxing the injectors

-aaron

 

[neuro]

3200 isn't that bad - a lot of people are full of shit when they say 18psi by 2800 on 14b.

However, any loud squeeling noise is usually a boost leak. Could even been your compressor housing o-ring. I'd leak test the intake to be sure. I know 90's show a lot lower voltage, and I'm pretty sure I've seen mid .7 o2s safely on 90's, making your .82's rich.

I bought some couplers that will fit snug today, so hopefully I'll have some updated logs where I'm leaning out and maxing the injectors

-aaron

I was just out driving around and just for laughs shut off the Profec. It takes 3200 RPM to hit 9lbs just with the actuator alone. With the Profec on, the difference in spool time to 16 lbs isn't much. Other logs I've done recently the O2 will read .85 or .89. I'll see if I can scare up a boost leak tester this weekend...I'm sure there's a leak in there somewhere. At least I hope it's just a leak?? Well, if the turbo's headed for turbo-heaven, I'll just have to get a bigger one a little earlier than I intended.