91L98Z28

Just wondering how many folks have made a 730/$8D setup work on a radically cammed motor? I'm talking 5" of vacuum at 1000rpm radical - that's about 83kpa at idle. It's an honest 6500-6800 rpm motor with a stick. Motor is currently set up with a holley 4bbl setup and is reasonably drivable, all things considered. street/strip application. smog equip is no concern in any way at all.

I know that the O2 sensor is going to be useless due to reversion etc., so at the very least idle is going to be open loop. Can a wide band be used to aid in tuning, or is this too radical for even that?

Any hints/tips on what this might be getting into would be greatly appreciated. Would there be another ecu that would be better to start off with? How drivable could this be made, or how tempermental might it be?

TRAXION

My new setup pulls ~76kPa at a 900rpm idle After several runs through VEMaster the car is doing great. The only thing left to do is to troubleshoot some tip-in stumble but, otherwise, the 730 is doing great at handling a cam this radical.

Tim

BIG_MODS

iTrader: (9)

How would you tune a '730 at that high of speed? The VE table only goes to 5600, and I've heard of modifying source code to expand it to 6400. I'd like to know because I want to build my next motor for some r's, but only if I can tune it. I imagine the .ecu would need to be modified also, but i'm just guessing.

Hey Trax what are the new specs on your cam? Gudging from your dyno graph you'd like shift past 7000rpm.

91L98Z28

Well for the most part, VE shoudln't be changing much at that high of an rpm, and would most likely be dropping, so if anything the car should just go slightly rich as the RPMs climb and the VE's fall, but the ECM uses the VE value for 5600. Some dyno tuning time equipped with an WBO2 would be helpful to make sure of this fact. If the VE was still increasing above 5600, the VE cell for 5600 could be increased a bit. This would make things a bit rich at 5600, but back to the desired range above 5600. At least - that's how i understand it at the moment.

TRAXION

That dyno graph is my OLD cam. I don't have any dyno or track data yet for my new cam. I can't reveal the specs ... not allowed. I want to but that is the deal I made with the guy who helped me pick the best cam for my setup. But - this cam is definitely a lot more aggressive in almost every way as compared to my last cam (my old cam was a 230/245 on a 113 with 0.550" lift at both valves).

You don't need to worry about fueling. The 730 can handle it just fine. Keep in mind that if you are at 5600rpms you are going to be in Power Enrichment mode. Using PE you have control up to 6400rpms. The previous post by 91L98Z28 was very much on the money. The VE tables follow the cars torque curve. Most likely your VE will be dropping after 5000 anyhow (probably sooner). So, it's not really a big deal.

Also - I got my off idle stumble fixed this morning. Yeeeehaaaa. It required significantly more acceleration enrichment than I would have ever expected. But, now it's pretty crisp! Go 730!

Tim

MrDude_1

so with the properly sized injectors, intake, ect...... exactly how high can the ECM go up to?

TRAXION

To answer that I think we need more people to tell us about their experiences tuning these cars with big cams. I can't think that I am the only one?

In any case - I believe that the 730 can definitely be tuned for a cam that gives 80kPa at idle pretty easily (given significant previous experience in PROM programming). 85kPa would be tricky but I do think it could be done. The problem with going higher is the following ...

Idling at 80kpa means that when you crack the throttle blades for part throttle acceleration that the MAP will increase to approximately 90kPa or so (I go from 76kPa to about 85kPa on part throttle acceleration). You don't want the vacuum to increase to a point where you would normally operate at WOT (95-100kPa).

Tim

MrDude_1

heh, i didnt make my question very clear.. is there a set limit of max RPMs that the ECM can goto? like a ending point where the computer just cant go any farther?

BOWTYE8

Here is some info on my setup.
Running 248/248 112lsa comp extreme solid roller . Idles in my 383 at 975 @70kpa. Idle is choppy but holds fine.
I shift at 7000 . I cannot confirm dyno power on this setup yet but I have tried to short shift from 6500 all the way back to 7000 with best times at 7000 shifts.
This is a ZF 6 speed with me in car 3375lb corvette.


I do have a W/b WOT right now is 12:1. all the way up. (I took a new position at work and have about 1 hour every 3 weeks to tinker )

My problem is drivablilty from 1200-2500. Auto guys has the looser convertor to take up some misses (please dont take this as every auto tune is off) I am just having a heck of a time getting my low speed tune in check. You will FEEL the EVER so slightly miss in a stick car. I have been at this for some time and will ask for help.

Dennis

Twilightoptics

So went do we get a VE master for MAF cars who have radical cams?!

TRAXION

Mr_Dude:
The Code is layed out in a fashion that has a VE Table Max of 5600 along with a PE Max of 6400. If you wanted to write your own code to expand the VE table then you wouldn't have any problem using any RPM that can be run in a SBC.

Bowtye8
- Make sure that you have your desired idle when in gear. The later code seems to automagically limit the max RPM in gear to 800rpms. The AUJP does this. It will idle fine in park at your desired RPM but as soon as you put it into gear it will drop to 800rpms.
- Set your Block Learn Cell RPM and MAP cutoff values to be in tune with your engine. This will allow you to traverse many more of the 16 cells which will give you much better driveability.
- AFTER setting those points and verifying that you are traversing many Block Learn Cells THEN run VEMaster and allow it to adjust the VE tables.
- You probably also need to increase your pump shot (AE vs. delta TPS and AE vs. delta MAP) significantly.

My car is doing pretty well in terms of driveability. The only thing left for me to work out is a cold start low RPM stumble which I am thinking is either too much start up enrichment or not a quick enough decay on that startup enrichment. I need to get my wideband on it to verify before making the changes.

Tim

91L98Z28

trax - are you still using the NBO2 for feedback even at idle? I was under the impression that lopey cams will let a lot of unburned oxygen into the exhaust making the nbo2's not work correctly.

TRAXION

I was under that impression too. But, I am STILL using closed loop .... I am still using the NBO2 .... and the car is doing great. And that is with overlap in the neighborhood of 20 degrees! I've literally doubled my overlap as compared to my previous 'aggressive' cam. I am still amazed that the car is handling it AOK. I was initially thinking that this was going to be hard to tune for part throttle but it wasn't. Theory would say that I would have a problem - but amazingly things are going very very well. I thought that I was going to have to run open loop at idle and then transition to closed loop based on RPM. But, I haven't had to go that route. Theory vs. Reality. Wowzas.

Tim

BOWTYE8

Tim,
Can you PM you email addy to me.

Thanks
Dennis

TRAXION

I sent you an e-mail. I have PM'ing disabled.

Tim

BOWTYE8

Sorry Tim- I only have my yahoo email availble now. I moved to Florida and ameritech is no more.
New email is bowtye8@yahoo.com

Thanks
Dennis

87_TA

Well my last cam was a HYD roller - not huge but alot of overlap.
230/230 560/560 @ 110 66 degrees overlap.
The car had to be run in open loop! If you did not it would run and drive great, but it would also glow the headers at idle no matter what you did with timing. You will know when you are burning the heck out of plug boots.
But if you run open loop the sky is the limit - a little harder to tune that way but still easily done.
The problem was it purged so much unburned 02 at idle that the car always thought it was lean - so ecm would add fuel.
Now I run a 242/242 solid roller @ 112 lsa and it easily runs closed loop and very easy to tune. Hope that helped some.

TRAXION

87_TA ...

Are you sure you are calculating your overlap correctly? If you are then we are using different procedures. Using my procedure your 230/230 only has 10d of overlap (not 66d!). Your 242/242 only has 18d of overlap. My cam has 20d.

Here is how I am doing it. See the attached file. This is for my OLD CAM. 230/245 on a 113. Note that the intake opens at 6d BTDC. The exhaust closes at 5.5d ATDC. 6 + 5.5 = 10.5d of overlap. This is using 0.050" method. Using this same procedure gives the 10d for your 230/230 on a 110 and 18d for your 242/242 on a 112.

There is absolutely no reason your 230/230 wouldn't have idled fine in closed loop. My 230/245 had the same overlap (1/2 degree more actually) and it idled great in closed loop. My current cam has 2d more of overlap than your 242/242 and I was able to get it to idle in closed loop. Yes, I degreed in my cam and know it's exact specs and yes it does have 20d of overlap using the generic 0.050" method.

Tim

87_TA

Nope.
Keith Black has great calculators and they seem to agree

But here are the specs you can see for your self.
Grind # cs-286h-r10

valve timing.............. open/close
@.006 in................37 BTDC/69 ABDC
..........EX................77 BTDC/29 ABDC

It idled great! But the headers would get to about 750 degrees
and glow after about 2 minutes of idleing.
After sever hours with a hand held temp sensor and timing from 0 degrees to 35 degrees with BLM @ 128 give or take a few.
After much plug reading, changing 02 sensors and qiute a few plug wires I realized there was no alternative but to run open loop and lean everything from 2500 and below.
The car ran great times and drove great but had to do so in open loop.


I degree my own as well, But I use the generic .020 method.
Some say that there are to many variables @ .050.
But not like it mattered, My cam is 3 degrees advanced now
because I did care enough to grind an offset key and did not want it to be retarded any and lose more low RPM power.

TRAXION

Gotcha - you are giving your overlap based on 0.006" specs ... not 0.050" specs. If you would have listed 0.050" specs then it would come in as I said ...

Your 230/230 - 10d
Your 242/242 - 18d
My 230/245 - 10.5d
My LEFI - 20d

In any case - that 230/230 cam isn't huge in terms of overlap. I'm not sure why you ran into the problems you did. Maybe we can figure it out? My 230/245 idled without the problems you mentioned and it had slightly more overlap. Very weird. What kPa did you pull at idle? That should help unfold the story. My 230/245 pulled 70kPa at idle. My new cam is tons more aggressive compared to that 230/230 and I am not having the problems that you did. It pulls 76kPa at idle. The 242/242 is similar in terms of overlap to what I am running now, but I still have more overlap and I can still tune it in closed loop.

By chance were you using a MAF on that 230/230? Just checking because there has to be something that may have caused problems running that cam. I wouldn't think that it would be a difficult cam to tune. I am thinking that maybe something was out of whack?

Tim

87_TA

tt

Ed Maher

1 big difference 87_TA vs. Trax is 406 vs. 350.

Maybe the extra cubes, while 'smoothing out' the cam are also allowing it to pump more unburned air smoothly.

I also see no mention of advance in 87_TA's cam. With more retard the exhaust is closing later which will also put it in a better spot to get contaminated with intake air. Even at lifts under 0.050" which is what i think he was getting at, maybe his ramps were slower too.

That actually adds up in my twisted mind anyway.

BTW, notice 87_TA says the bigger 242 solid can run a closed loop idle. Maybe it was just something about that cam/engine combo that made it weird?

TRAXION

just trying to figure out what was going on. Ed brought up a good point about the 406. However - that should make it easier to tune since bigger cube motors can tolerate more aggressive cams. Full explanation is in Vizard's Chevrolet Camshaft and Valvetrain book on p. 50. Another variable is the exhaust. If you have a restrictive exhaust then the exhaust will backflow into the intake. Were you running an restrictive exhaust? I'm running long tubes to a 3" exhaust. LTs are really good at creating velocity to pull the charge from the motor.

More thoughts ...
Did you tune the BLM Cell boundaries for RPM and MAP?
At what RPM did you set your idle?
Were you running a heated O2 sensor?
WHERE was the O2 sensor in the exhaust?
What brand of O2 sensor did you use?
Did you mark the balancer for TDC after FINDING TDC during your cam degreeing? In other words - did you verify TDC?
And, of course, the kPA at idle?

Tim

87_TA

I know ,sorry



In theory you are right.

Well good point, SLP shorties, single 3" flowmaster. but I would think that would be enough. hmmm.
But I also ran the solid with that exhaust/headers for a while.
Now I have same setup as you. LT's,dual 3" Y,SINGLE 4".

Now the shorties are on my camaro with single 3" -that car just went trapped 129mph with those though lol.

Good point again - but I still have not.... besides isnt 128..128 still? maybe not right great usage of cells,but still correct mixture?.?.

800/850

yepper

Same place yours was with the shorties.

Well initially Bosch,then I bought a universal junk one and then another Bosch. - all the same results.

Ohh yeah Idle kpa was 67 range.
Yep, When I installed the AFR's I varified TDC.
Both heads - same glow. I remember after the change I was very optimistic... I thought that the big 2.08 valves in the Canfields may have contributed - no go..

Mind you through all of this I went over valves the first time I noticed just in case there was an exhaust valve to tight - not the case..
I tried Initial timing from 0-35, none of which varied temp more than 50 degrees.
Tried longer line to the MAP to help with spikes - no good.
Raised the Delta map for A/E just in case the fluctuation in KPA would do it.
Changed all surounding areas of VE in idle to same value to try..nope..
The only thing that I may question is that my 406 is a 6" rod engine which also hurts exhaust scavaging - but now with this cam its all good.
Ex temps great, ex smells acceptable , plugs look good.

Tim , What is your overlap @ .006? Just curious, maybe that will tell us something.

1bad91Z

iTrader: (1)

Could someone calculate over lap for my cam and a buddy of mine's cam?

My cam: CC XR276HR-12 in a 355ci
.503/.510
224/230 @ .050
112 LSA
108 ICA

Friend's cam CC retro fit Hyd. roller in a 406ci
.510/.540
229/246 @.050
112 LSA
108 ICA

Are any more specs needed?

TRAXION

3d for the first cam
and 13.5d for the second cam
These are @ 0.050"

Tim

OMINOUS_87

Learn some basic math, JK Mike!!!

Anyway here is handy dandy link you can play with for calculating overlap: it uses the .006, seat to seat, or advertised specs of the cam, all which mean the same thing when you look at your cam card. It does not inculde any calcs for .050 specs, so your results will not be comparable to Traxions.

http://www.empirenet.com/pkelley2/Overlap.html

OMINOUS_87

EDIT: DP

Matt87GTA

Here is some data for ya'll (not sure if it is useful or not):

Specs for my 383 setup can all be found at my site (see link) but the basics are in the sig.

Idle MAP is about 70kpa @ 800 RPM. Pretty smooth, no glowing headers, all closed loop - all the time . BLMs are 126-130 as of right now.

So far I am finding the same results as Tim as far as ease of tune when I thought it would be a bear. I disabled AE and PE and got after the VE tables with VE Master and it really drives pretty darn well at this point. BLMs are still a little rough here and there but are falling into place in short order. AE and PE still haven't been worked on much. Problem is, winter is here, car is sleeping . Probably won't be able to touch it again until spring....

Anyways, I got a readout for my particular cam and my @ .050 overlap is also 20* ..... (18* IO, 2* EC). Overlap @ .020 is 51* .....

87_TA

Overlap @ .050 does not tell whole story ,though it tells you alot.
overlap @ .006 will tell your total overlap.
Sometime people just state the overlap @ .050 and that MAKES NO SENSE . You must remember that there are many contributing factors IE, Ramp rate, base circle which people who don't understand fully cams do not know .
Somthing to remember....
As was the case with my cam having 66 degrees overlap being reason I had to run open loop.
Or something else with that combo.

Also as a note to help - I drove my car that way for weeks and weeks before I knew I had a problem and would not have know until I ran it in a dark garage to check for plug wires arching.
Ran great! Idled and tuned great! Headers were excessive hot...
Also had that cam in my 350 prior and did not notice any problems..
But its all over now

OMINOUS_87

OOOOOOOPS!!!

The link, dont I feel like an idiot!!

http://www.empirenet.com/pkelley2/Overlap.html