ctd

iTrader: (1)

I'm getting quite a collection of injectors, I tried a set of modified injectors. In SD only the idle & off idle VE cells did not tune nicely at all & it ran poorly. I swapped in a set of ID 1000's & the VE cells dialed in much nicer immediately, I actually posted somewhere the difference in those tables.....major. Still not happy with how it ran regarding surge & buck, 17* of overlap, I swapped in a set of stock LS2 injectors for an experiment. The ID 1000's ran ever bit as good if not better than the LS2's in the low speed area. So ID 1000's injector's even @ low pulse width run & tune equal to or better than the stock injector's. No luck with modified injectors.

I removed them as I'm happy with my NA power, had consider FI was the reason for going with that size of injector. I still have them if you are interested they have 300 miles. Also at this point I had re cam to 10* over lap & reduced duration by several degree's

From there I went to LS9 injectors were the low speed issue's were aggravated further. Then to LS7 injectors which made a noticeable improvement in the low speed area, but they quickly run out of fuel.

David_viny

I just want to clarify what I said before about my surging/bucking, that its very very minimal and in fact the more I thought about it my last drive, I think its mostly the play in my crappy rear diff. Just don't want to scare people away from big cams, its not bad at all. I daily drive mine all summer. I made a vid of my car cruising. I've been meaning to make a better one with my go pro but this gives you an idea.


The jingling noise is loose change in cup holder, other noise is my shitty rear that needs a rebuild.

I don't normally cruise that low rpm like that, its just for demonstration.

SilverSmoke

Looks/sounds like around 2:50 your getting some surge/buck around 1300-1400 rpm. Sounds like its enough to bounce you in your seat, which wouldn't be too comfortable for me when cruising around. Looks like your cam has 10* of overlap as well. Do you feel your car is bouncing you around a bit in the seat around that rpm a lot, and around 1700 rpms?

JakeFusion

iTrader: (7)

So, I want to bring this back up from the dead. I got light throttle surge cured by adding a ton of airflow to the Follower table.

However, when I lift off the gas, I buck under 1600 RPM (I have 16 degrees of overlap and need more gear). I've added airflow to the cracker tables, but it didn't seem to help.

Should I play with the VE tables/MAF transfer some more? I'm still a bit rich when I let off, but that's because when the TB snaps shut, airflow is killed. I need it to stay lean. Should I try adding a **** ton of airflow to the Cracker? I have a **** ton in the follower...

ctd

iTrader: (1)

I folded, my project goal was perfect manners without compromise in the tune. So I reduced the overlap with Martin's cam selection & re visited the entire valve train.

The end result is near perfect manners, no fiddling the tune, no drivers meeting, improved mid range power & no power loss in the top. The cam is easier on the valve.....

This is my third camshaft, 17* to 10.5 & now 4.5*, I've not lost power & now I'm making more.....guess what page I'm on

RonSSNova

iTrader: (3)

I like it!
No drivers meeting.
Toss me the keys please!

Ron

Russ K

iTrader: (1)

I hate to say I told you so. But I'm glad your new cam fixed your issues. And I'm still loving my 234/242/117+2 cam with 4* overlap.

Russ Kemp

Exidous

iTrader: (11)

I had a bit of surge with my 228r and that had 0* overlap @ .05". At first I thought it was the timing because the AFR was dead on. Adding or removing timing did nothing. All that was left like SE said was Airflow. As you are lifting you may want to remove air rather than add. My surge was always near the really low TPS % so I focused on getting those areas of the Airflow tables dialed in. All but pretty much eliminated the surge. I had to add some for the % TPS that caused cruise and accel and remove a little for the TPS % that caused decel. It's a fine line for sure but certainly manageable.

ctd

iTrader: (1)

I should clarify my position & why decided to change out the cam. I was to the point were I have to agree with soundengineer. The problem is I was not prepared to start drilling my nice NW 102 TB. Not being a experienced pro tuner @ that level I would have been entirely on my own as I could not find anyone with experience willing to help.....including soundengineer.

Two broken valve springs had me in fear so I was going to have deal with that issue.

Exidous

iTrader: (11)

Easiest way to tell if you need to drill is what IAC counts are required for a proper idle. Ideally you want between 40-70. Above 70 you'll probably want to drill. Below 40 you may have a leak.

When I first had everything installed with my 228r I have about 130 on the IAC. I started small and stepped up one bit at a time until I had the proper counts. It's important to make sure the blade is closed properly and you are getting 0% on the TPS.

ctd

iTrader: (1)

What if you are DBW?

ElecTech

Not the same. DBW uses strictly blade angle to control idle air and drilling a hole can usually add more trouble than it helps. Proper sizing of the TB and quality construction are more important, in this case. I tend to go to the smaller side of TB sizing to gain better drivability when a car is a daily. Most people go too big, too soon.

ctd

iTrader: (1)

I understand that & agree, just wanted to be sure the poster basing on IAC counts understood there are DBW's which do not have IAC counts. As well the drill the blade comments are not about idle control.

Also I agree with soundengineer that you might drill a throttle blade to add air somewhere off idle either cable or DBW. I think this is where Jake is at, my days of drilling blades are back with Carbs....no choice, that was for idle control & transition to off idle. Easy way for me was to re cam, that has been a win win for my situation. My skill level with HPT is not where it needs to be to dig out the number set

eaglegoat

Drilling a throttle body is a hack, especially on a dbw car. If there is a "professional" advocating for this approach then they are a hack too.

Exidous

iTrader: (11)

I understand very well DBW vs DBC. I forgot to mention it. I've been DBC for so long due to the swap that I forget it exists sometimes. :-)

Drilling a TB in a DBC car is NOT a hack if the cam is big enough. Sometimes the IAC stepper motor is not capable of providing enough air for a bigger cam. You want to have the proper range of movement through all operating conditions. When the motor first starts the IAC opens way up. If the cam is too big for the TB as is you'll have issues due to insufficient air. Too big usually refers to a lot of overlap.

DBW drilling shouldn't be necessary.

ctd

iTrader: (1)

The discussion here is not about idle it's about getting more air available during buck & surge conditions.

Russ K

iTrader: (1)

More air=more fuel to keep the AFR correct. It won't do anything for surging or bucking when you foot is on the gas pedal. You can increase the throttle cracker to hold the idle higher when the car is coasting in gear with your foot off the gas pedal. And to increase the idle speed when you push in the clutch, you need to raise the rolling idle airflow adder table.

But if you increase these tables to much, you will have a cruise control/hanging idle effect, and your car will still buck & surge. Cams with too much valve overlap buck & surge at light throttle/low RPM due to the exhaust that is pulled back into the cylinder during the intake stroke. Same as a car with a weak EGR valve spring.

And a 4000 rpm stall convertor will smooth out cams with a lot of valve overlap.

Russ Kemp

ctd

iTrader: (1)

Agreed 100%, you have to agree if the volume of air is changed @ a given point & AFR is correct the motor will run differently?

I have two examples in mind, the first being a air intake restriction @ WOT. The MAP sensor is verifying what is happening @ WOT, you correct the fuel for AFR & all is good. You remove the restriction & the AFR goes lean, you correct the fuel & bring the AFR back in line & you are probably & should be making more power. Both AFR's are correct, the motor runs differently.

The second is carb days, bigger cam & the motor is pissed off @ idle. I changed my low speed jets so I have proper range of the idle air/fuel needle screws. Drill a hole in the blade, the motor goes lean so I jet the low speed back up for proper range of the air/fuel needle screws. The motor is now very happy as it has more ilde air .....BRAF in todays speak.

Two opposite ends of the spectrum, my understanding is you can have a correct AFR in any condition. Not necessarily a happy motor.

I follow your comments regarding the cracker & follower, would it be reasonable to think that if you are adding excessive airflow to those tables you might be out of range of correct operation? Drilling the blade so the motor gets more air, only if it is happy you can back down the cracker & follower tables working within a smaller window & their range of control?

Russ K

iTrader: (1)

Not different, just increased RPM

Yes, you will make more WOT power.

On a carb, when you open the throttle too much to keep it idling, you uncover the idle transfer slot. Then the fuel is being pulled out of the main jet, so now the idle mixture screws have no effect. So by drilling the throttle plates & closing them, the idle transfer slot is under the throttle blade and now the idle mixture screws will be able to change the idle AFR. Nothing similar to BRAF in a EFI engine.

If the AFR is correct, that's all you can do as far as making the motor happy.

Yes, if you add excessive airflow, you will get a hanging idle/cruise control effect. On my car, I have .8 g/sec airflow in all RPM's of the throttle cracker and the rolling idle airflow adder table. And I have the enable/disable speeds at 1.0 KPH & .5 KPH. The throttle cracker table is in use with the clutch out & the rolling idle table is used when you push the clutch in. These tables have 0 effect on the drive ability when your foot is on the gas pedal. The rolling idle airflow table prevents the idle dipping/stalling when you push in the clutch (above 1 KPH). And the throttle cracker table helps with the idle dipping when your coasting in neutral with the clutch out to a traffic light.

And drilling a DBW throttle blade is a hack method from the LS Edit days before there was a scanner like Hp Tuners to see the STIT & LTIT values.

Russ Kemp

JakeFusion

iTrader: (7)

I actually drilled a small hole on my NW so I could close it down. My FAST 102 was barely open to have the right IAC counts. But I added a 1/8" hole to smooth out the airflow and to allow me to reduce the blade angle. That helped some. I think I probably could have taken a lathe to the blade to open it up. When it shut down completely, you couldn't see light around the blade like you could on the FAST.