The Results...........
 

Well Fellas here is the scoop.....
The weather was less than co-operative, but I did get to run three times. On the way down to the track ~2hr drive about 1 1/2hr into the drive my SYS engine light same on!

I stopped the car and checked the obvious fluids etc and then started the car with the laptop connected and watched to something strange...I think it was the heated O2 sensor. Because I noticed on my WBO2 that the A/F at cruise, which is usually 14.6-14.8, was now at 12.5. Without being able to view the underside of the car its tough to say. I should also add that the SYS light went off while the laptop was connected that is why the O2 looked alright. Shortly further down the road the SYS light came back on and the A/F went crazy again.

Went to the track and said hell with it, I am running regardless.

One other thing it could be is the MAF sensor. I gutted it the night before But the g/sec was functioning just as it should have been. I spoke with another corvette owner there that was running 11.4sec on juice and 12.4 n/a with nearly the same combo + 383c.i. He said that he had experienced the same problem after gutting due to the MAF seeing unrealistic air flows???? Any truth to that?

Well enough of the tech crap lets get to the racing.....

Traction was tough to get in first and some spin in second. Here are the results.

I should also add the guy that had the vette said this track is VERY slow. He runs .2-.3sec quicker at every other track he runs at. And about 1 MPH fast too.

Here are the results:

RUN1

R/T .672
60' 1.967
330 5.621
1/8 8.646
MPH 82.44
1000 11.293
1/4 13.507
MPH 101.84

I was pretty disappointed at the results although the ET were a bit quicker...
I took it out again for another try........

RUN2

R/T .674
60' 1.974
330 5.571
1/8 8.554
MPH 82.37
1000 11.154
1/4 13.336
MPH 103.91

I was a bit more please at least the MPH were back.....but still no 12's


I spoke with the vette guy and he said that perhaps your running too much timing. I replied that I have the chip programmed to 25.3* at high load and 3000+ RPM He said he was running the stock chip! That has nearly 36-38*. I tried running that and my knock counts were ridiculous. I got kinda mad walking over to the car and I remembered I had my distributer wrench with me. So I told dad I was going to retard the timing some. I loosened the cap and rotated it back ~.5 in. Not knowing how much, noone nearby had a light. Out to the track I went....

RUN3

R/T .891
60' 1.940
330 5.505
1/8 8.463
MPH 82.97
1000 11.042
1/4 13.204
MPH 104.55

Man did that one feel stronger too. I wish I would have had slicks on, I bet it would have been a high 12's. Seems that I must be running too much timing????? I guess I need to stop thinking about it and just give the car what it wants.

Today are the local drags and although its not an ideal track (its an airport) I will get to run many times and prehaps I can find the sweet spot for my timing. Then adjust the chip to represent the change.

Any ideas why I would need to retard the timing sooo much? Everyone says that the AFR heads do not need very much timing??? Who knows.

Overall I am please not so much at the runs, but rather that the timing change made a pretty good improvement. That tells me that its me/tuning and not something mechanical. Also one other thought is that the balancer's outer piece had moved and 6* is really not 6*. That is why I had to retard the timing sooooo much.

Today I am going to retard it more and see what happens.

Hopefully the rain hold out.

All in all, I think with some slicks, skinnies on the front, and alittle more tuning I should be consistanly running in the 12's.

Give me your thoughts. For now I must take the car out to the dealership and poke around for the SYS cause.

Thanks guys!

Re: The Results........... (ski_dwn_it)
 

I had the same problem. I think the 219 cam builds lots of cylinder pressure below 3000 rpms, and it results in knock with regular timing curves. Too bad I didn't get to play with it before I broke 3 pistons from going lean. My total timing in the chip is 36 degrees, had 4 degrees retard every run, and initial is at 6*. Every time I retarded the initial the car picked up mph. The 700r4 lugs the rpms down after the 1-2 shift also, and I was getting lots of retard (somtimes 15 degrees) right after each shift of the tranny.

You may want to record some runs and take out a little timing right after the shift.

Re: The Results........... (ski_dwn_it)
 

It can be hard to easily pin down the performance bottleneck, but I think yours will be a mid 12 second Vette when you get it all dialed in. It is very likely that you were indeed running very rich (and down on power because of it) due to SYS light indicating some trouble or another. Porting the MAF is fine, but did you change any programming to accomodate the airflow capacity increase?

Every engine is different in its ignition advance needs, I'm currently running 42 degrees at WOT above 4,000 rpm with no knock sensor activity at all (I actually tested it up to 44 degrees advance with no problem, I dialed it back to 42 just to be safe).

I know that you have probably already been carefully checking out all your engine details, most likely that it is a combination of a lot of little details that is holding you back.

Have you considered spending some time on a chassis dyno and trying a series of timing and fuel pressure experiments to bring out the best in your combo? Your combo is underperforming currently and i'm not sure of a good direction to send you for the missing power. Hopefully those who are more familiar with the L98 will chime in and help you unlock the horsepower.

Thomas

Re: The Results........... (ski_dwn_it)
 

Here is the scoop on the SYS light. Just as I had expected! The heated O2 sensor rubbed on the braided ground that goes to the one bell housing bolts. As a result it rubbed through and was grounded out. I spotted it immediately and fixed it. As a result the A/F at cruise went right back to normal. :D

Yesterday at the strip I ran consistant 13.5-13.6 but the track sucked bad. All through first was a joke no matter how I took out. Part of second was spinning too.

I really think with skinnies on the front, slicks on the back I would see 12's. The last run at Beaver Springs was at nearly 105 MPH. That is the range that Beach Bum and Ralph said I should be at. Perhaps with some traction I would reduce my 60' and ETs.

What do you guys think?

My A/F is right around 12.5 at WOT reading the WBO2. My base timing has to be at close to or below zero....That kinda has me conserned, but every time I lower it I go faster. What could be the cause of this? Could I have installed the cam wrong? Distributer? Balancer bad?

I did not degree the cam, but rather installed it using the Cloyes adjustable timing setup with the 3 keyways. One for normal, retard, and advanced. I am 99.9% sure I used the normal keyway and installed the upper and lower sprockets with the dots dead lined up. That should give me the correct degree correct?

As for the balancer, I inspected it like everything else before re-installing it. Everything looked OK.

The highest air flow reading from the MAF sensor on the scanner during one of my runs was 250.5 g/sec. Does that sound about corrrect? That was at ~6000 RPM.

I did notice however that some 2 knock counts were recorded during the run. Right after takout is where they occurred. There is absolutely no bog or hesitation anywhere in the runs. Its pulling VERY hard the whole run.

Maybe traction is problem. Surely from what the rest post for 60' times, mine is notone of the best. I took Beach's advice with staging. Trying to just barely trip the last staging light. Perhaps is my driving :lol: But I don't think so.

Any ideas, comments welcome. Per the other vette owner that was running a 383 with the same setup+nitrous at 11.6 sec. He said the best his stock bottom with the upper as is would only run 12.8 sec. So I am not too far off. He also said that the track there is .2sec slower every time he is there. Others said the same.

The track/airport yesterday is a joke. Just fun for the locals. Cars that usually run in the 10's were running mid 12's and sometimes 13's! :crazy: I beat a car that is ussually in the 11's consistantly! Made my car look fast! Too bad he was spinning the first 1/8 of a mile. And he had more rubber on one rear tire than my car has combined. So I would negate any information supplied by yesterdays runs.

Please give me some advise. I can send you logs, data anything that might be a help. Thanks a million!

Re: The Results........... (ski_dwn_it)
 

Ski,
Tune for max MPH. That is your horsepower indicater. Many, many sbc's want and need 36* and much more. An example above cites 44*. You want to keep advancining until you achieve the greatest power or knock, which ever comes first. The fact that YOUR engine does it's best with less advance than others is proof that you have done something (maybe several) right. The less the advance required for maximum results is a sign of greater combustion efficiency. Your ports, valves, combusion chambers, piston tops, and deck heights, must be well set up to require a lesser amount of advance for maximum output. Don't worry about the cam. You have put together a "killer" combination. Just keep tuning for max output and be happy and proud that you achieve the best results with less advance than some others. Keep it up and good luck.

Re: The Results........... (ski_dwn_it)
 

Hi ski,

You've got a lot of tuning to do.... but based upon what you said about the track itself and 10 second cars running 12's.... I'd throw out these results and get yourself to a different track and then work off those results.

You should easily be a mid 12 car and even run into the 11's.

good luck and let us know when you can hit another track.

cheers,
Beach

Re: The Results........... (Beach Bum)
 

Jesse, i think your mph should easliy be over 110!!! It sounds like the converter has striaghten out your bottom end problem, but now your tires are the weak link as i predicted. However, your tune is still off. get the mph up in the 110+ range and then start working on hooking the whole thing up. You might want to look over the timing map i sent you a while back. It's a good starting point for your combo. With that map i run 6 degrees initial and i have found 8-10 degrees initial slows me down. I've never tried less than 6, but probably should. Then mess with your fuel curves using the wide brand for feedback. You've got an easy mid 12 sec setup that can also be tweaked into the 11s......lots of examples exist. You're making progress.

Re: The Results........... (ralph)
 

Ralph,

Here is the problem:

When I add timing via the chip, like running your timing table you supplied, I get tons of knock counts.

I had to back the timing tables at WOT down to 25.3* to get rid of the knock.

These were all at 6* of base.

Now here is the crazy thing. While at the track, we thought we would retard the timing a bit more. When we did it we were in a hurry and actually advanced it! This gave me a .2 sec better run and picked up some MPH with no knock! They kicked me off the track after that for not having a helmet. I thought the cutoff was 12.99 for a helmet...oooops!

We messed with the timing some more yesterday and the car still has no knock counts and the base timing is ~14*. So now I should be running 25.3*+8*(difference between computer thinking its at 6*, but really at 14*).

The car is MUCH stronger, and traction is a tough to get on hard takouts. I know my MPH will be even better.

But the BIG question is why will adding timing to the ECM throught the chip give knock while adding it at the distributer doesn't :confused:

If I could get the car to take the timing at the ECM I could problably be running were you guys are saying I should.

With the distributer I am just making Global changes....

Please give me your thoughts and thanks for all your help already.

Re: The Results........... (ski_dwn_it)
 

Disconnect that knock sensor for a pass or two !!! I never have mine hooked up. I think you have something else going on that needs attention, you are wayyy down in power vs what you should have. To go from 104 to 112 which is more where you should be is probably a solid 60 hp. Put it on a dyno and see where you are actually making your peak HP. That will tell a lot. I personally think even if with the stock chip you could run 108-110 mph traps, I think you have a valvetrain problem or ??? not sure.

talk to you later
Beach

Re: The Results........... (Beach Bum)
 

OK. But how the H do I tell that? I mean there is no loud clicking/knocking noises coming from the valve train. Everything is new. I even had some experienced guys listen to it and none of them said anything sounded suspicious.

The car never misses a beat going down the track, but obviously there is something causing the missing power.

Still no one has been able to tell me why I can add timing at the distributer and achieve ~36* of total timing without knock, but not be able to add it through the ECM without tons of knock. I truely think once this is answered it will bring to light some VERY important keys to me making the power I should be.

Thanks guys, together we have to have the answer.........let hear some suggestions.

:cheers:


[Modified by ski_dwn_it, 7:29 PM 5/27/2002]

Re: The Results........... (ski_dwn_it)
 

Jesse that timing map i gave you should work for your setup. I know it's working on at least 3 cars without problems, including mine and Beach's. Why that is causing knock and not the distributor, i don't know. The only difference is a complete shift in the curve vs a different curve. Maybe there is a spot in the curve that is causing the problem, or maybe the knock sensor is too sensitive or something. Try running without the sensor hooked up like Beach said, just to see what hppens. My sensor has never worked either, so either me and Beach are destroying our motors (unlikely since we been racing them for years) or there is something else wrong with your setup.

btw, how did you setup your valves??? Dont listen to anyone tell you that you need more than a 1/4 to 1/2 past zero lash. I once tried TPIS recommendation for 3 turns......damn thing barely ran. I assume you got the correct spring and have your geometry setup correctly.

Re: The Results........... (ski_dwn_it)
 

Ski,
I have been having the same problem on my setup for a year now. I'm only getting 108 mph on a good day. I've had multiple people look at it and I still haven't seen any significant improvement. I know this doesn't help you, but I feel your pain.

Glenn

Re: The Results........... (ski_dwn_it)
 

I remember when you first tested your new modifications. You were way down on power, until you hit 3000 rpms. If I followed this correctly, you changed converters to avoid the lower rpm range. You never fixed the low rpm problem, you just side stepped it by changing the converter. I don't know what's wrong, but you might keep sight of the earlier situation as you dry to diagnose the present problem. I think they may be related. Good luck.

Re: The Results........... (CFI-EFI)
 

Ralph and all,

Let me first say that the converter I had in there was either shot or not the stock one. It was extremely tight. But not getting into a bunch of details, I don't think I side-stepped the issue.....I will however keep it in the back of my mind and not dismiss the problem.

Ralph the valves were set up on your recommendation......

Here is what I did...

I first bought a "high tech" adjustable pushrod. I then painted the valve stems with black marker for easier visual ID of were the RR ran. I found mid lift on the cam with an indicator. Positioned the RR on the stud so that the RR was mid-way on the valve stem. I then brought the adj. PR out till it just barely touched on the RR. I then wiggled the RR back and forth just to make sure I was in the middle. This left a real nice visable line when everything was taken off. I did this at least a dozen times or more on different locations just to make sure. I took about 2 night till I was satisfied with the readings. All reading were 7.200" +/- a hair. So that is the size PR I ordered.

Upon assembly of the RR I lowered the PR down through the lifter valley making sure each was seated just right and had assembly lube. I then slipped the RR down over the stud and screwed the nut on the stud. I turned the nut till I could just barely feel the RR apply pressure to the PR while I was spinning it between my thumb and forefinger. I then make 1/4 turn and stopped. I then took and allen wrench and tightened the inner lock nut till it bottomed out. Next I took the torque wrench and turned the nut once again to ~35 ft/lb (which was about another 1/8 turn). This was very carefully done for each location. Intake and Exhaust.

This was the first time I had ever done anything like this and I was very careful to take my time and follow the advise I was given to a T.

Does anything sound fishy?

A few persons said I should have added another .100 to whatever measurement I got on the adj. PR. for hydraulic lifters. Many here said no, so I didn't. Could this be the problem?

I had the valve covers off several times trying to get an oil leak stopped and also when I got new V.C.s The RRs appeared to be riding from 1/3 of the way across towards the intake to about 1/3 from the the exhaust side.

The PR was chromoly and made for guides....

The heads were ordered with the spring and valve upgrade necessary for the 219's .560" lift. There stock 190s come with springs only good to .550" lift. Therefore I paid another ~300 bucks to get the upgrade.

I really have no way to tell for sure if that is what they sent. I guess I would have to take their word for it. The springs do however have an orange painted strip on them if that helps. I guess that is how they identify them. Can someone verify if they are the right ones.

Ralph I think I am going to try your timing curve again and poopie-can the knock sensor. If the friggin thing blows it might be the best thing that could happen. Then it's 383 time totally forged with nitrous! :smash:

Can I just zero out the timing retard tables or do you guys just unplug it? That is set a code if I just unplug it right? Will it effect performance with a code? I want to give it a fair shot when I try it. PLease advise how you disabled yours. I have read that some put a resistor on the end of the wire to simulate the sensor....Just for the test let me know the easiest way... Thanks

Hope all this information helps.

Thanks for spending your time helping... :cheers:


[Modified by ski_dwn_it, 11:13 PM 5/27/2002]

Re: The Results........... (ski_dwn_it)
 

Sounds like you did the valves correctly assuming you had the lifter on the base circle. If you pull off one of the rockers, the wear mark should be about center of the valve stem.

i currently have my sensor disconnected AND have the retard tables zero'd. However they dont have to be zero'd....i was trying to trouble shoot a problem and my ESC is toast and was throwing out weird voltages, so i just wanted to ensure that no retarding was happening.

Did we go over the calc of your CR??? I've been helping a couple of other guys sort out their setups and forget if we had this discussion or not. If my memory is ok...i think we did and you were cool. If you have 58cc chambers you are at least at stock CR and if you used a thinner gasket, you're probably up 1/2 a point.

Gotta be in the tuning.....especially since you're doing it yourself with almost no experience. Keep plugging, you'll get it, and by then, you'll be the expert tuner. Good luck

Re: The Results........... (ralph)
 

Hey be nice :lol: What a confidence booster you are! :lol: :lol:

To answer your questions about compression, yeah we went over them and everything checked out. They were all +/- 1 or 2 PSI.

I had the heads milled to 58cc and used a .038" gasket. I even called Summit after I was having problem and made them go to my order and verify that is the one they sent me.

I too would have to agree that its something in the tune holding me back. I wish I lived near someone that really knew what the H they were doing. I would hand them $1k if they could get it straightened out.

But like you said with time I will get it. I just can't wait to go through the traps and see 12.5 or so seconds. But then I will probably be saying to myself: What the H is wrong that I can't get 11's :smash: Thats what keeps us all busy thought and what its all about.

My fiance had to go to a dinner tonight, but she said she would hurry home so I can try the car without the knock sensor and your timing tables. I will let you know if it makes a difference. I am going to just ease into it at first. ;)

Man I just wish I was having a stumble or something in the runs that would be accounting for the loss of MPH. The car feels as strong as the Chevelle with the 509 Merlin. Even my dad said it feels stronger, but obviously SOTP is not always quicker.

I will let you all know. Thanks again guys. You make the persuite for power that much better!

Re: The Results........... (ski_dwn_it)
 

I don't know for sure what to tell you... I'm not their and my small brain after work is too tired to attempt to absorb all of the information you have forwarded.

But to everybody who is underachieving with this combinantion, my only advise is to pay very, very close attention to every little detail on your set-up.

The below is just a few things that at one time or another has cost me anywhere from a tenth to over a 1/2 second.

* Gaskets from plenum to runner slid blocking the ports. Cost me 1-2 tenths.
* Spring went weak, cost me 1-2 mph and tenths.
* Bad plug wire and undersized header gaskets combined cost me a solid 40hp.
* Ignition - rotor/cap problem cost me 3 tenths.
* TB didn't open all the way cost me about 1/2 mph
* Bad plugs cost me about 1 mph
* False knock through a hooked up knock sensor cost me over 1 mph and almost 2 mph
* Injector harnass broke and cost me about 8 mph.
* Timing set back to 4 degrees initial hurt me a solid 1-2 tenths
* Recently even a dirty air filter cost me 1.5 mph in the 1/8th mile.
* A few others I cannot think of right now.

Obviously the above all occurred at seperate times over the years, but with just 2 or 3 small problems you can really knock the crap out of your power capability. In most cases above the motor seemed to make decent power driving on the street, but once at the strip, the timeslip told me the truth.

I recommend you start with air flow and start taking everything apart working your way down stream. Ohm out your plug wires.... a bad plug wire will still fire the cylinder, but kill your power, especially up above 4500 rpm.

I know this is not a lot of help.... but you'll figure it out if you remain committed, have faith in your set-up... its been proven.

good luck
Beach Bum

Re: The Results........... (Beach Bum)
 

Thanks Beach...

Here is the scoop!

I took Ralphs timing table and applied it to what I already had. In addition I unhooked the knock sensor.

OH MY! Hello power! I am running 36.2* when PE is invoked. My blms are now a bit lean, but that is expected. A/F at WOT is 12.2-12.4, a bit rich but I added some fuel for testing. Thought I would be safe, rather than sorry. I can easily fix these items on the next chip.

I tested it on the highway first, and eased into the power while carefully listening for pinging. Nothing at at...After I was pretty sure everything was OK I went to my testing grounds. Came to a stop and reset the computer so I could log the run and record 1/4 mile pass.

Stomped the gas and to my amazement the car did not even move! Its just cat there spinning and ever so slowly lurched forward gaining speed at every second, I hit my shift point and shifted and the tires still spun in second then grabbed. I went through the 1/4 but left up shy of my mark and coasted across the line....The computer returned a new best of 12.4 at 109.86MPH. I was truely elated!

I know the computer is not very accurate, but its still a good reference to use.

The car overall is MUCH more responsive and feels like there is a whole lot more power available. Hopefully this cures my loss of power. I sure think it has, but time will tell.

The car used to stall after hard runs and when put into park at times. Now it idle perfectly.

No codes were set and I am a happy camper. I will lean out the mixture a bit tomorrow and see how it responds.

The next time I go to the track I may take 3-4 chips with different fuel curves and see how each performs.

I really think the knock sensor was the problem....There was no way I could get above 25.3* of timing without tons of knock counts. I have nearly 11 more degrees now and I can definately tell the difference. I was probably only utilizing ~80% of the possible power available.

I will do some plug reading tomorrow too, just to make sure that everything is OK with the tune.

Beach those are very good point to make on the items that usually get overlooked. I am 99% sure they are all correct though. I took my time and paid very close attention to detail. It was either you or Ralph that gave that advise, I just kept repeating it in my head....:yesnod:

Thanks guys and essecially Ralph for sending me the timing table way back. Just wish I would have had the rocks to disconnect the sensor before, but I'm glad in a way I played it safe.

Hopefully now I can join the ranks of the individual running 12's!

Can't wait to hit the track again. It will have to wait though, this weekend I have my two other kids! I will have to do a burnout for Hunter! He's 5 and everytime he sees a vette he says he's going to buy it with his piggy bank money! :lol:

Thanks again guys!

Re: The Results........... (ski_dwn_it)
 

Jesse, first of all, congrats on finding the problem to this thread. I have a few questions though. Keep in mind that my engine is stock except for the mods listed below. Would disconnecting my knock sensor help me? I know that our motors are totally different, but after seeing how much of a difference it made for you, I can't help but be curious. In one of the e-mails that you sent me you mentioned that knock could destroy an engine if uncontrolled, so I'm guessing the answers NO. I have never hooked up a laptop to it and I don't know if I'm getting knock counts. My Timing is based on SOTP feel.
Also how much of a difference do you think a custum chip would make? My goal is to tweek what I got without getting into any serious engine work.
One last question out of curiosity. Do you know what your car ran in the 1/4 mi before you did the engine work?
Talk to you later....Steve Penjuke

Re: The Results........... (Triple Black 88)
 

I was going to post in my last update that I was no condoning everyone to run out and disconnect their sensors. I was having definate false knock and am still going to keep a VERY close eye on plugs, etc. You should be able to tune without disconnecting it.

That is correct.

Its definately going to help, but you need to taylor it to your cars needs.

My car ran ~14 flats and once in the 13s at Englishtown. You have a strong running car, don't get greedy and ruin it. Be methodical in your search for power. One bad desicion, could make you an unhappy camper. I would never disconnect the knock sensor without first getting a laptop and doing some experimentation.