I've been having a nightmare trying to tune out a hotrod I'm doing. Ive got it now where the car "runs" (aka 55mph cruise) great. But its REALLY and i mean REALLY lackluster when it comes to power. Worse then my stock 350 tpi. It's also drinking gas like no other. I can't figure out if its the timing or what.

Anyways the engine is:

350 + .030" flat tappet
Heads are from an 85 LB9 - 58cc ported very nicely w/ 1.94 1.6 valves
Cam is a straight pattern .447" lift 222* duration, unknown overlap

All topped by a stock TPI system (plenum ported, base cleaned up etc) with 22lb injectors.

The rest of the powertrain is a TH350 channeled into a mopar 8 3/4" rear with 2.76 gears.

This car is incredibly light weight (nothing to it) so the 2.76s shouldnt be the problem. The thing is just totall lethargic at WOT. The RPMs at cruise are tame due to the low rear gears, so it shouldnt be sucking gas like this either (10-12 mpg).

I have tried working from a 350 timing map and have it running good. I've also tried a 'vette timing map (thinking the 58cc chambers may have a similar timing requirements). But it hasnt really gotten any seat of the pants faster. I could beat this thing with a 305tbi truck, it's so slow.

So to narrow it down to a specific question:

is this cam just incredibly bad for the combo

Thanks,
Matt

 

Have you tried putting a WB O2 on it?

 

If I can talk him into removing his exhaust and adding an o2 bung I will, but odds are slim.

 

I don't know how you can tune it without it.
Waste of time IMO otherwise.

 

if its TPI, doesn't it have a NB O2 sensor already? if so just put the WB O2 there & hook the 0-1 volt output to the ECM & log with the 0-5 volt output.
another thought, does it have cats?

 

So, how much of a fee are you getting for this and are you going to share? Normally, I would lock this post because we are for guys who "Do-It-Yourself" to their own cars, not "bins for hire".

However, I find your the setup intriguing and DIY membes an opportunity to see how to tune something like this vehicle. So this is your lucky day and I am going to help point you in the right direction.

Frankly, I would toss out the gears & TH350, and go 3.55s with a 700R4 to start. But I doubt that will happen as these guys typically collect "junkyard parts" that are available dirt cheap. But that is the first problem with this combo IMO; so I'll move along from there...

As for tuning, you really need to get a WB and get that AF ratio around 12.8. If he WON'T allow a bung, then a chassis dyno is the next best alternative, and you will need to do some fuel tuning there. You don't mention if it's SD or MAF. Being a hotrod, I will assume it is SD as most of those guys want the "nice clean TB".

I would suggest finding a calibration similar to a peanut cam auto LB9 for the spark map. Those heads won't tolerate any spark (and frankly the real source of the problem IMO). You'll be lucky to get 25* of REAL spark advance (assuming you have disabled the knock sensor). If not, that's probably your problem because those heads will be triggering the KS as the advance begins to amount to any significant size and then pull a TON of spark out. If you hook it up to a scan tool and adjust for the KS, you will probably find the effective total spark advance is in the low 20s (maybe even in the high teens).

If it has a KS, disable it in the bin and set the retard to the lowest setting just above 0* (so you can see it kick in) and then tune WITHOUT the KS. Advance your spark curve slowly until you begin to hear detonation, then back it off and that's as far as you can go.

Small chamber heads, no matter how well they are ported and especially iron heads; just cannot tolerate much spark advance. Bin thar, dun dat.

If he want's his hotrod to be fast, I wouldn't toss out the cam; I would toss out those heads (along with the TPI) and buy a set of AFR180s and an HSR (and maybe change the gears & tranny as I suggest too). It's been my experience that those hotrodders come up with some combos that "look cool, but are awful for performance"; and the truth is sometimes brutal. But, assuming your client want's the looks and doesn't want to do "the real fix"; you will have to do what I suggest with the starting bin & then modify the spark in conjuction with the KS accordingly.

Good luck.

 

 

First of all, this is my fathers hotrod. I am not charging him anything to do it. I should have stated this from the beginning.

TH700R-4 is not an option. A TH350 barely fits between the X-Member of the frame as is. A 700R will not fit without a tubular x member. There's a method to our madness, and frankly, being a hotroder doesn't mean we scrounge up junk thats cheap and cobble it together. Most hotrods are very well done up peices of engineering. So what is with your comment?

WB is a possibility. I will have to take it out of my trans am though. I see plenty of other guys around here that are getting a decently good tune without, I didnt figure it would be impossible to get anywhere without it.

I've already had the KS disabled since the get go. I know the heads cant tolerate much spark, we actually made a lot of gains when I pulled a bunch out at cruising speeds, got rid of a burble we had and made it run much nicer.

He doesnt want it to be a rocket, but, if you drove in it youd see that it should, even with whats there, be way faster then it is. Its a total dog. Its not even as fast as a stock LB9 car, and it weighs half as much.

So assuming the timing is somewhat close, could fueling be causing such a lack of power? I figured if WOT was lean it would pop or misfire.

 

Does it have a narrowband?

Did you check the #1 cylinder TDC mark on the balancer to make sure it's correct, and set base timing accordingly?

With such bad mileage, I'll have to assume it's both/eithor rich and/or retarded timing. You've pulled out part throttle timing, and it improved, so that leaves it being rich, mosts likely.

Also, don't go for a year chasing your tail. If it doesn't respond to much, then you have to consider the possibility of the cam being in wrong (retarded), transmision problems, dragging brakes, etc...

You can stick a wideband up the tailpipe. It may melt the plastic a little, though, but it's like it shrink wraps it, not burns it off. If you do only part throttle with it that way, it probably won't melt it.

If the cam is on a 106 LSA or something rediculous, then you may just need a converter and gears. If it's 110-114, you may be able to live with what you got, but even a 2000 rpm converter would wake even a stock cam up.

 

Last statement....WHAT is the torque converter for this TH350. given the low ratio rear axle, if you have a tight converter, you may always be in PE at low revs most of the time. Not good for either performance OR Fuel Economy. I would suspect a better matched TQ Converter would help....

 

The torque converter stalls at around 2500RPM. The rear gears used to be 3.55. We only changed to the 2.76s a week ago because we were getting such terrible mileage. It barely helped. Didnt noticed much of a decrease in power, thats how weak it was even with the 3.55's.

 

Another thing... it does have a regular narrowband o2 in it. The tune we have runs a good 124-132 blm going down the road so it "should" be somewhat stoich at cruise, yet it still just drinks the gas like no other. Maybe I have unreal expectations.. but I figured a three speed with 2.76s should be able to at least muster upper teens fuel economy. I have suggested that he swap the o2 for a new one or try a different one and see if the BLMs are similar. Next step will be to investigate how he installed the cam, quadruple check base timing and then work on fueling I guess. If its not spark it must the fueling, right?

 

That cam is a dead ringer for the GM L-79 cam with a 114 LSA. A decent N/A cam and a good boost cam. Overlap @ .050" is 222-228 = -5* so it should tune half decent with the TPI intake.

Look at what the NBO2 voltage is. It sounds like with the high load it spends most of the time in the high KPA areas that are tuned rich from the factory. It is probably in the 13.6 AFR range (10% ethanol reference). Since it is light then you can tune it leaner. It could also use more spark advance also if it is that light.

EDIT: The stock NBO2 values are tweaked so that in the high KPA area the engine runs richer than stoich. and burns more fuel.

 

I would go over the basics first. The engine only needs a few things to run properly. Good compression, proper a/f ratio, and proper timing (both ignition and valve). Your engine obviously lacks one of the key ingredients. It is up to you to determine which one. I would first check the base timing to ensure that it is set at 6*. Once the base timing is set, reconnect the "Set Timing" connector and verify the ignition timing advances above the 6* base. I would also check the fuel pressure with the engine running and the vacuum hose disconnected. It should be around 42-45 PSI. Hook up the vacuum to the regulator and it should fall a minimum of 1 psi for every 2 in/hg of vacuum the engine makes. That cam should idle with around 14 in/hg of vacuum @ 700 rpm. That means that it should fall to between 35-38 psi. With the help of a 2nd person, I would then choke the wheels, put the transmission into gear and powerbrake the powertrain against the brakes to make sure that fuel pressure rises up to meet the demand. You might lose 1-2 psi as the fuel system is put under load, but it should not decrease much more than that. You might also check the idle vacuum and cranking compression. If either one is way off, it is reasonable to suspect a valve timing problem. Once everything has been eliminated, proceed with the actual electronic tuning via the prom.

As far as smaller chamber heads being detonation prone on a 350, I have never run across that. I ran 32* total advance with NO knock retard and no pinging in a 5,000+ lbs van with a mild ZZ4 cam and 9.5:1 compression on 89 octane. Fuel economy was in the upper teens on the highway with 3.07 gears and a 700r4.

EDIT- Just going to post up my timing table, timing corrections, and VE graph of what I came up with. I tuned my engine for both SD and MAF running the TBI setup.

 

I highly agree with changing these, here is why. With the hotter than stock cam, it is going to be much easier to push the high KPA readings at light throttle than a stock engine. A stock engine makes 18-22 in/hg of vacuum and a modified one will only make 13-16 in/hg. Going down the road with a 222/222 @ .050 cam, you will often see MAP readings of 85-100 KPA with as little as 20% TPS reading. Stock you might see 50-60 KPA at the same 20% throttle. Lack of mechanical advantage from the 3spd trans and 2.7x rear gear is going to mean that you dip into the throttle more heavily to accelerate than a 700r4 with 3.4x gears would.

Speaking of heavily loaded powertrains (your engine qualifies with the cam, transmission and rear gear). This is what a stock 1995 G20 Van (5,000#) with a 190 HP 350 TBI, 4L60E, and 3.08 gears uses for an O2 bias table and PE table. There is the Target O2 voltage table and two TPS% tables. The first table is TPS% vs. RPM for initial enrichment (13.7ish:1) The second table is TPS% vs. RPM for PE (12.1:1).

 

Matt, it's a pity that when they were engineering the chassis that they didn't engineer it for a 700R4 (with a locking torque convertor). It would solve many things. I guess it might be a kit and those kits are designed to use "cheapest, most readily available parts from junk yards"...such as SBC 350, TH350, Mustang II front ends, etc. It's not a slight, it's just what kits do - and while they may be "well engineered" when they were developed (a few years ago), they are not well engineered for to take advantage of today's technology. TH350 is old school and hasn't been used in over 25 years.

Moving on. The NB sensor DOES NOT give a good tune. It can develop a reasonable tune for part-throttle but it is totally useless for WOT. The NB is strictly a switching device designed to go "rich & lean" that develops an overall tune (in part-throttle) that attains stoich. Nothing more, nothing less.

And this is what I think your biggest problem lay (assuming you have tuned the spark to the point where just 1 more degree causes detonation in WOT). Also, "tip-in" and your P/E engagement (via the TPS) need some tweaking.

If you play with the P/E engagement, you can make if feel like the secondaries of a carb kicking in (without even flooring it). That can have a lot to do with it "not feeling fast".

As for poor gas mileage, one of the biggest contributors to the 3rd Gens good fuel economy (besides fuel injection and 700R4) is the locking torque convertor (and another good reason to go 700R4...which I understand will not work). If you get that tune down, you could try invoking Highway Mode to increase the fuel economy. With Highway Mode and proper locking of the torque convertor on my L98 (when it was still basically stock), I was able to attain US 30 mpgs. So it can be done.

BTW, you still haven't stated whether this is SD or a MAF setup (and which calibration).

 

Your 350 has 64cc heads...those are not small chambers. 58cc is a small chamber, and iron makes them quite detonation prone. And 54cc as used on 305s are even more smaller (and trickier to give any spark).

But, Matt is running without a KS, so he can see how much spark they can tolerate before he can hear the ping. I have found with numerous dyno testings, that the trick to getting power with small chambers and lazy gears is to get up the spark curve to it's max value as quickly as possible without triggering detonation. If Matt can get 32*, FANTASTIC - see if it can get a bit more. But, I think Matt is going to find that he doesn't get even close to 32*.

 

Seems memory serves me that prior to the Vortecs, my 350 HAD a pair of ported 081s and prior to that a pair of 14022601 305 HO heads with 1.94/1.60 valves in them and some unshrouding around the valves. Those are 53cc (I cc'd mine at 56cc after chamber mods) 305 heads last time I checked. I ran 32* of timing with no knock retard out of them. I did however notice that when I put my 3,500# boat behind it, it would go into the low octane retard mode running on 89 octane, but still would not show any appreciable knock counts after going into low-octane mode.

 

Its a 1946 frame. So... the 700R4 wasnt even a twinkle in somebodies mind back then. Its amazing the TH350 even fits. But if they wanted it to be modern, it would have had an LS1, since TPI is old school and hasnt been used in over 15 years.

Anyways, I'm going to have to give all these replies a triple read and try some things out. If I get ambitious I will pull my wideband setup from my Trans-Am and hook that up to the 46.

Oh yeah, its a SD system, $8D mask.

http://mattodoom.com/newta/7-9-07/IMG_1249.JPG

 

I forgot one thing that has actually already been mentioned. The cam sounds like a clone of the old GM 151 (350 HP 327). That cam is not known for great low-end torque, only a little HP, and dismal fuel economy. It makes peak torque nearer 4,000 rpm. The TPI setup resonates between 3,200 and 3,600 rpm. He should invest in cam that puts peak torque in exactly that RPM range. Positive things will happen when the cam and the TPI come into harmony at the same RPM, can we say TORQUE. I had an isky 258 supercam (202/202 @ .050, .425/.425) in my 305 TPI with ported 14022601 heads. I had 3.08 rear gears and my passing acceleration in 3rd gear was 10 seconds from 65 to 85 mph. That sounds like alot, but its a 5,500lbs aerodynamic brick and the little 305 was only turning 2,800 rpm @ 65 and 3,500 @ 85. The 350 short block helped things ALOT over the 250,000 mile 305 short-block.

 

We have another cam and lifter set available to try, its a comp cams 12-402-4, specs: 212/218 dur, .444/.444 lift on a 114 lobe seperation.

Would it be worth tearing the front clip off the car and doing a cam swap? (AKA: will swapping to this cam make things a ton easier and be a much better combo with what we got?)

 

That cam should give more torque. I would be even more enthusiastic if it were a roller cam. Is the block a roller block or pre-1986 (non-roller)? If it were a roller block, there are lots of L98, LT1 & ZZ4 roller cams floating around that you should be able to pick one up dirt cheap. Unfortunately, retro-fit is cost prohibitive.

Have you tried running any of these combos in DeskTop Dyno? While I take DD's HP/TQ estimates with a grain of salt. I do find it useful for comparisons for component changes.

I do look forward to you WB results. Once you get the fueling dialed in, then you can try tuning the spark again. I assume you are doing all tests with a scan tool. What is the max spark (with the KS set to minimal value) you are able to run before you encounter detonation and at what rpm?

 

Sorry, but I haven't been documenting the history of your vehicle. But, let's not hijack Matt's post by arguing this point.

As you know, there are tuning differences between a "wet intake" and a "dry intake" system (such as TPI). I base my comment solely on the large number of posts that I have helped people tune their vehicles over the years both on DIY Prom and in real life; on basically stock engines and modified engines (many very heavily modified...as I am attracted to those just for the "challenge").

Running a lot of spark is not necessarily a good thing. GM is purposely going to heads where you do not need (or want) a lot of spark advance to attain max power. It greatly increases the life of the engine if you can achieve basically the same amount of power with a lot less spark.

In fact, when it comes to dyno testing, I will often experiment with the spark and discuss with the person if we can achieve 99% of the max power (before detonation occurs) at a lower spark advance. Sometimes you can pull 4-6* of spark advance out and still achieve 99% - sometimes not.

Anyway, I will be happy to "rumble & roll in the mud with you" in a PM if you wish to continue this debate. But in the meantime, lets just help Matt.

Okay?

 

Just looked at this thread, my 2 cents that its your classic mismatch of parts. From someone whose done a lot of porting, even with a good job done, those heads and a stock TPI intake are for a completely different rpm band than the cam. Also despite the fact that it's light weight, the lowest gearing I'd ever go is 3.08's and it really needs to be more, especially if your father has done the typical "hot rod" thing and but big fat tall tires on the back, remember taller tires really sap out gear ratio, not to mention adding rotating mass and rolling resistance.
But really I need more info ... what's the compression ratio? that cam and a lower CR would be very lazy. what do you have the timing set at? Lots of discussion of it, but havent seen the #'s. BTW, for once I find myself in disagreement with Grim Reaper, if the fuel tune is right, I've not had much problem running plenty of timing with those and similar heads- provided gearing and cam selection don't put unnecessary load on the motor, and we've stayed realistic with CR. Especially in a light car.
How tall are the tires? Did you get any flow numbers on the heads? I've seen many people actually reduce flow on those heads with porting. Particularly at the low lifts we're talking about, or get a high flow # but kill the charge velocity, which cause the heads to really, hm , well suck basically. More info on the cam would be nice. What's your rpm at 60 mph? Especially with a bigger than stock cam you can actually make mileage worse by taking the car too low in it's RPM band. Especially with a higher stall converter, can you say slippage causing bigtime mileage loss? The lack of info on the cam isn't helping. I assume the duration # is at .05 . In which case its fairly big for your combo. LSA? Overlap? dunno could be huge- which would be a problem, and I'm assuming it is, cause if it was small you shouldn't be having thosue problems. with those heads I'd really look into something with a dual pattern. In hot rods like that I've had a lot of luck with the 4x4 series of extreme energy cams from Comp, a little more LSA, dual pattern, and aggressive lift curves. Done any intake tract modifications? Obviously you're datalogging, any wierd sensor readings? Any possiblitly of an exhaust leak causing faulty O2 readings? Running headers that may not be heating up the O2 sensor enough? Nothing worse than the computer tellin ya it's lean or right on when it's really rich. How do the plugs look? You've disabled the knock sensor, any chance your actually getting some detonation? Oh one more stupid thought for you. I have seen more guys use the wrong timing pointer with their harmonic balancer then you would ever believe. Remember that chevys had some that TDC was straight up, and some where it was at about 2 o'clock, and if you mismatch them your timing will be fubar.

Without knowing more about the rest of your combo, assuming a head swap is not an option, I'd go with a much smaller cam, something along the lines of comp cams part number 12-256-4. 210/218 duration at .05, .449/.456 lift, 112 LSA. I assume he's already got headers, make sure they're a small tube, not some huge honkin super comps. Then depending on tire size, I'd for sure step back up to a gear set at least in the mid 3's. If the tires size is real tall, maybe even low 4's. Here's a good informative link on gear ratios
http://www.4wheelparts.com/gear_ratio.html. I'm running out of steam now though, sorry for the way long winded reply.
John

 

Rhuarc31, you are absolutely right - we have not seen many numbers or specs. No spark, no fuel, no scan logs.

Matt, post your bin and the info above.

 

Wow, lot of questions there. First: tire size. Im pretty sure they are no taller then whats on m T/A (26"?). Here's a picture: http://www.mattodoom.com/newta/7-9-07/IMG_1246.JPG rear rim size is 17x8 to give it some perspective for you.

The cam specs you recommended rhuarc are very close to the other cam we have. We'll probably end up swapping to that one. The cam is as they have stated above, the 327/350hp cam. I dont know the compression ratio - I didnt build the engine. It has dished pistons - how much I dont know - so I'd imagine in the 9's somewhere. I didnt do the headwork, I dont know who did the headwork - it looks professional. They are not hogged out by any means, just cleaned up nice with a good bowl blend. Pinned rocker studs.

We only have the two gearsets available, 2.76 and 3.55. With the 3.55s in we were screaming down the highway, it's just too much gear. The headers are small tube - probably 1 5/8 block hugger shorties.

It has the correct balancer and timing tab. The car "runs" great. Idles perfect, runs smooth as silk down the road. Just slow at WOT and bad gas mileage.

As for heads, its these or the original heads (tbi truck heads). They are really bad heads, have huge indents in the intake ports where the pushrods come through and swirl ramps, etc. The block is a flat tappet block, no roller cams for this one.

I dont have the .bin or logfiles available to me on this computer. I'll see what I can get.

To get a couple things out the way - at this time there is NO chance of new heads, different gears (other then the two we have), a 700R swap or any of that. I realize that these parts are less then optimal, but im not asking so much for parts suggestions as to advice on how to make what we have work as good as it will. There will not be any significant amounts more money put into the car - divorces will do that. I can tell you right now that theres not even a possibility of going back to the 3.55's. The only thing that could / is going to happen is the cam swap to the 212/218 .444/.444 cam. Other then that, I'll just try to get it going as good as I can for him. In a few years I'm going to buy it off him (was a father/son project) and I will probably swap it to an LS1.

Thanks

 

If the rear is a MOPAR 8.75", I might be able to help you with a gear between those two ratios.
What case is it? 489? 741? 742?

See link for how to identify.....

http://www.autohobbydigest.com/8_75.html

I do have a 3.31 ratio (non posi) that is either a 741 or 742 (need to check) case that I would swap for the 3.55 unit. Just need to know if it would fit. Also need to know if you want JUST Crown Wheel and Pinion, or a whole differential. BTW, I could BRING it to Michigan (Detroit area) around Thanksgiving, as I will be there......

 

He doesn't want to trade the 3.55 center section. It'll probably be going on eBay.


Anyways, I went out there with the laptop today and got all plugged it, let it hit closed loop and took off. Got to the end of my road and the laptop shut off (battery is shot now I guess). It's just one thing after another. Yesterday I heard him mention getting an intake and carb, so I don't know. Not going to get anything done this year without a laptop to datalog. I might put the wideband on it and check out WOT for kicks and try to make adjustments that way.

 

Matt, do you have any scans with the car in WOT? If so, please send it and I'll look inside. Also, please "cut out" any extraneous portions. I.E. If you took 5 minutes to warm up the car and drove another 10 minutes before you did a WOT run, cut that portion out as I don't know where you actually opened up the car (but you do) and I don't have time to scroll through trying to find it.

As well, cut-off the portion after to keep the file size down.

This is really the only way I can look and try to see if anything stands out in the way of your tune. Else, I won't be able to help you.

 

Dished pistons? Boy matt, with 64cc heads, depending on what head gasket was used, I guess more in the 8:1- 8.5 range on the compression ratio, which isn't really a problem, but if your cam has alot of overlap it could create the situation your describing creating an even lower effective compression ratio and costing you mucho power and mileage down low. Everything else sounds real good, so if it's not there I'd guess in the tune or we're missing a simple mechanical problem somewhere. I assume you've pulled the plugs after a run and read them. Best bet being to do a run where you can pull over immediately and pull one so you don't burn off any deposits running in a different area of the curve. The tires look maybe a bit taller than a stocker, but not by much, I'd say you're right there. If they're 26inchers you should be turning close to 3k at 60, which is kinda screamin, even the 2.76's will put you over 2k. And if you had this problem before the gear swap, I don't think it's the issue, just that it's exarcerbating it. Oh and you're right I'd stay the hell away from those truck heads. Though lookin at the pic of the car, I'd bet it's heavier than you think.

 

They arent 64cc heads. They are 305 heads. Something like 54cc. Should be in the 9ish to 1 compression ratio.

As far as the weight goes, the entire inside of the car is empty. No interior. The body doesnt weigh that much (we've carried it) so basically all it is is a motor, trans, rear and frame.

 

305 LB9, and even 305 HO heads are all 58cc. He should have no problem running 30-32 deg WOT total spark with those, I have done it on my 10:1 327 w/ minimal to no KR. Yeah you can't run 36-38 deg WOT, but you don't really need to either.

 

Ill keep that in mind. Since my laptop battery crapped out on me ive been having to do this "burn a chip, go do a WOT run" thing. Its getting old fast haha. But I've been steadily adding spark into the upper kPa's and so far no pinging.

 

Another thing, I think I found at least a significant part of the problem.

First of all, the car doesnt have a tach (dunno why not). Anyways, I threw one of those cheapo sun pro's on it to check it out, because I'm a tach lover (even with an auto). Anyways, at WOT the stupid TH350 is shifting out at about 3900RPM. So for the next few runs i shifted it manually and held it till around 5k. Its got a little more umph up there but still vastly slower then my L98 GTA. So what's needed to alter the shift points, spring and weight kit? Or an adjustable modulator?

 

Yes, governor spring and weight kit. It is the same gov that the 700R4s use. Although 3900 is too low for anything, even stock. You may have some problems with that trans

 

Oh yeah, sorry, someone else said 64cc, caught it when I scrolled back up.

 

Well. I wouldnt expect that little sunpro tach to be anything all that accurate. Its probably more likely in the low four-thousands. Regardless, its too early. The trans shifts really good and it is fresh. Ill have to get a peak inside the governor area and see if something came off and is causing the early shifts.

Too many projects... not enough patience!

 

I know this is a little off topic, but how do you edit the files? I'm using Tuner Pro RT and have some rather long logs, that I may want to break up.

 

Get an AC/DC power invertor that plugs into a cigaretter lighter (or off the car's battery) and they plug your charger into the 110volt outlet - then you can run your laptop indefinitely.

I'll give you a quick way to dial in your spark curve "from scratch" that I have used successfully over the years on a wide variety of engines.. Just make sure the KS is disabled and preferably the fuel is reasonably close. As well, remember that the spark will affect the AF ratio, and may need to be re-adjusted.

You need to start with a fairly low values (but not ridiculously low) and increase the spark in 1* increments starting from 3,200 and up rpm until you hear detonation. STOP whenever you hear the slightest amount of detonation. You can do the WOT in just 1st or 2nd gear so you don't even need to go that far from your neighborhood to speed up the testing. If you should hit 36*, stop (for now)

Once you hear detonation, then back off 1* (you can later fine tune for that last 1/4*) - that is going to be your maximum from 3,200 to max. Then start decreasing the starting rpm (by 100 rpm) below 3200 rpm until you start to hear detonation. (ie 3,100, then 3,000 etc until you hear detonation) Then back off the spark until it disappears. Then start reducing your rpm by 100 rpm again, until again you hear detonation. Again, back off the spark until it disappears...repeat until you are down around 2,000 rpm.

It is BEST to do this at sea level (100 kpa), which will always have the lowest spark advance. As you increase elevation (lower kpa), the thinner air can tolerate more spark advance. If you find a nice mountainous area, you can then use that to work your spark curve for the lower kpa values. It generally has a direct relatationship (and curve) similar to the highest kpa values.

The above will work until around 75 kpa, which is quite high. After that, you are in the "part-throttle" area of the table.

This is just a method I have found to sucessfully tune WOT spark curve. If it works for you, great. If you need more explanation, feel free to ask. If you have a better method, then use that instead.

But I have found this very useful in dialing in the spark curve for any EFI engine which I have the ability to modify the spark tables.

 

That seems OK to get it roughed in. I usually see knock on the sensor without hearing it. The knock is completely silent...I have good ears. I am guessing that he will have the same problem as it occurs with most engines. Do you pull timing for the sensed knock or leave it?

 

Under the datalog menu you can hit "Export to CSV(Comma seperated values)" This will create a .csv file of the log. You can then open this with excel and make graphs and other pretty things.

Also, Grim - thats a great idea for the spark! Thanks for that.

 

Quick question. When considering "total" spark advance I'm adding the spark table along with the PE Spark for each RPM. Is there any other tables that get added in there or just these two?

 

Looks like I'll have to learn how to use excel.

 

Net Effective Total Spark Advance = Main Spark + PE - Retard (From scan of KS).

If you look at a scan log, you can reconcile this by taking the "Spark Advance Total", subtracting your "Knock Retard" to get your net Effective Total Spark Advance.