WOT Tuning
 

With the recent results I've gotten at the track and on the dyno, I have started looking for ways I can optimize tune for WOT. I heard about doing "plug cuts" before but never took the time. This time I did. Very revealing.
Looks like its running "a bit" rich and that I have some fuel to take out. Next step is hooking up my ZT-2 at the collector. My suspicion is that the WB at the dyno is on the lean side because its at the tailpipe. Using my WB at the collector should give me a more accurate reading. Attached
is a pic of an NGK BKR7E plug on the left and an AC Delco 41-602 on the right.

Re: WOT Tuning
 

Interesting. I've never cut plugs before, but am very familiar w/ the concept of reading plugs. So...a Q for U:

Were either of those plugs pulled immediately after a WOT run, or was there a period of normal (closed loop) fueling and/or a shut-down and cool down and a restart? Point is, plug reading to determine fuel rich/lean, etc, is pretty quickly compromised by conditions outside those being tested - hence my question.;)

P.

Re: WOT Tuning
 

Paul,

The answer is that neither were pulled immediately after a run and then shutdown. However, as you look at the porcelain, there are 3 regions. Closest to the tip being idle, mid-section indicates cruise, and the bottom is WOT and therefore the need for the plug cut. Ideally, the bottom should have a wispy tan look to it. I may try to borrow my wife's tool for examining childrens ears. That supposed to work too but I had these plugs laying around and thought I'd give it a shot. After the track, I decided to try a plug one step hotter but I still need to pull fuel out of the WOT zone of the VE MAP.

Re: WOT Tuning
 

I use an 8x eye loupe, but I'm too cheep to start cutting my platinum plugs, I guess ;)

Anywayz, mebby ya need to have a spare plug or two and shut 'er down at the trap and coast into the turnout area. That way the results won't be compromised.

A quick read some may find interesting::)

http://www.dragstuff.com/techarticle...ark-plugs.html

P.

Re: WOT Tuning
 

Paul,

As much as I would like to do that, I am more concerned with removing and tightening plugs on hot aluminum cylinder heads. Very few places where I could go thru that cycle around here so a certain amount of contamination is unavoidable.
BTW, that was one of the articles I read on plug reading. One of the reasons I got the NGK BKR plugs is that they were less expensive but provided the heat range I was looking to test. Once satisfied that I have the right heat range, I can then move up to a Platinum or Iridium equivalent.

Re: WOT Tuning
 

Thats what anti sieze is for I use it on the pro stocks every pass
Bob

Re: WOT Tuning
 

Thanks Bob. I do use anti-seize when I install the plugs.

Re: WOT Tuning
 

Guys, as I recall the LT-5 is programmed for a 12:1 fuel/air ratio with the secondary injectors on. It will be faster if you lean it out (ideal stochiometric ratio for gas is 14:1), but it is programmed rich to protect against detonation. Let's face it, the 90-92 cars have 2nd generation ECMs and only read every 25 RPM. With Speed Density control and batch fired injectors there is not much to work with here. You can detonate the hell out of the car without it responding enough to prevent it, just on a bad tank of gas.

The 93 up cars have the P8 ECM that read every RPM. I've often thought that there would be more driveability there but have not found anyone that has made the change.

Re: WOT Tuning
 

Not to pick a nit, but I double checked and the LT5 injectors (according to my sources) are sequentially fired, unlike the L98. That notion is supported by the fact there are individual (ECM) injector control leads on the Zs - not "ganged" (L98s, etc) for what it's worth.;)

P.

Re: WOT Tuning
 

Here's the latest on my playing around with spark plug heat range.

First .jpeg shows ground strap heat range indication. Yoou can see that the color changes near or at the gs bend.

Second .jpeg shows the fire ring at base of porcelain. The plugs are (left to right),
BKR6E, AC 41-602, BKR7E, TR55XI. Looks like there's more fuel to take out at top end but I'll need to monitor KR and AFR using my WB. However, it tends to confirm that my suspicion is that the WB, at the tailpipe, used by the dyno operator is reporting lean.

Re: WOT Tuning
 

I'm sorry to say that, regarding LT5 applications, there isn't much correct in this quoted post.

"Ideal stochiometric ratio" describes a chemically balanced mixture - it has nothing to do with best performance. Leaning out the AFR of a performance engine at WOT to anything approaching 14:1 is a recipe for disaster.
Has has been pointed out, the LT5 injectors are not batched fired.
The computer runs plenty fast to respond to rpm changes. The post makes it sound like the computer sits around and once every 25 rpms does something. That isn't correct. And while a bad tank of gas could cause a little detonation, there is a knock sensor which will prevent "detonating the hell out of the car." And really - do people get "bad" tanks of gas any more? Lastly, the computer used in 1993 was not noticeably different than the one used in previous years.

Marc

Re: WOT Tuning
 

Buy a WB with recording capability and have it plumed into the collector. I am all for reading plugs but having a actual track picture would pay for itself in the end. Marc is right, 14.7 is not anywhere near your target AFR for load based tuning. Not sure what Marc uses as his baseline for WOT but it would be a good start. I would think money spent on suspension improvements would have a better return than trying to find additional HP through calibration changes.

Tyler

Re: WOT Tuning
 

Tyler, you keep that logic up and we'll have to award you a Beacon of Reality award. Can we do that on the forum? :razz:

Seriously, Marc has spoken the truth also. There has been this urban legend posted before about the mysterious "P8" ECM in 93+ cars. It isn't true, at lease to the best of my knowledge...still got the good ole P4.

Todd

Re: WOT Tuning
 

Not certain if this was directed to me or someone else. I think I previously stated that I do have a ZT-2. Used it for 2 years on my old 84. Haven't installed it yet on the ZR deciding how to route it into the cabin. As for finding additional HP from calibration changes, so far with a change of plug heat range ($1.50/plug) and modifying both SA and VE tables(FREE) where it counts, I've been able to pick up about 2- 2.5 mph in trap speed. IMO, pretty good bang for the buck and I don't think I'm done yet. I'd agree that tires should be on the short list.

Re: WOT Tuning
 

Kind of both. Repairing a broke LT 5 can be expensive. There is a lot of collective wisdom on this forum that hopefully can help. I do not know your knowledge level on the calibration tables so I am urging caution. If I were to race a ZR-1 the first thing I would address is the radiator bypass and how it functions. In stock configuration this system starts routing water around the radiator at 5200 rpm and by 5800 you have almost no water being cooled unless you slow the revs back down, leaning the motor only increases the likelyhood of blowing a head gasket in this situation. The fix is simple but does call for a heavy duty radiator and cutting the thermostat pressure spring and blocking the bypass.

It is obvious you are comfortable with data monitoring so there is no reason to fly blind. Take the laptop and record a session then look at temps and rpms then look at the AFRs from your WB O2 to see just what fueling is doing throughout the run. What happened to spark? As previously stated the computer will pull timing out and you will never notice without going back over the data. Oh yeah start the session with enough fuel so you will have at least 1/4 tank at the end of the session. The dual pumps suck a lot of fuel and it does not take much to lean out the motor when a turn or stop pulls fuel away from the pickup.

Tyler

Re: WOT Tuning
 

Interesting. Thanks for that bit of advice.

Last year I datalogged a number of runs at the track. That led me to re-curve spark avoiding the knock retard. Trap speed went from 111 to 115mph.
The most recent changes I made were based on datalogs from my dyno runs a few weeks before. Having done some plug cuts, I began to suspect that the WB used at the dyno may have been reading lean although the dyno charts showed a pretty
steady 12.8 - 12.9 AFR up thru 7000rpm.
Hoping to go to track one last time this weekend. Back to your point however, if I lean it out any more, I will be datalogging looking for any knock. I'll keep you posted.

Re: WOT Tuning
 

Here is a picture of which spring to cut. When you cut the thermo like this it is always open for water flow as long as the bypass does not open to pull the water around the radiator which is why I put a 1 in plug in the hose to block the bypass. Do not do this unless you have upgraded the stock radiator.

http://deliquescence.net/~tyler/misc/Thermo.jpg

Another point to consider is that the best HP in a LT 5 is made when the water temp is between 160-165 deg. This was tested some years ago by a tuner and I asked Graham B directly and he agreed that the test was accurate. He also made the point that OEM water temp was a compromise between emissions and power with emission winning the day. If you go back and look at your earlier data runs I would be interested in what you see when you compare rpms to water temp. IE what happens when you hold a rpm over 5800 for a period on time.

Tyler

Re: WOT Tuning
 

Tyler,

Thank you for that. I will review my datalogs altho I think the main issue is maintaining a 160F temp before a run. You know you just sit there waiting to get up to the line. :handshak:

Re: WOT Tuning
 

Tyler,I have no problems running my car at the track with a Ron Davis and a 170 Therm. I double stinted the car with Dwight at the track this past summer and the coolant temps were never a problem. The oil temp was a different story though.

Re: WOT Tuning
 

The bypass works by pressure. The stock radiator has a low (restriction)flow rating and once the water pressure gets to a certain point (5200 rpm) the spring on the thermo begins to open and water goes around the radiator. The Ron Davis has a higher flow rate (less restriction) which raises the flow needed to open the bypass spring. With the cut thermo I could run 160 deg-165 deg with A/C and outside temps of 95+ as long as I was moving.

Lane Goldstein (Fastlane) used a switch in the cockpit to turn on his fans with engine off to cool down his motor between runs. You can do the same thing by turning off the motor but leave the ignition on and turning on the A/C both fans should come on.

Tyler

Re: WOT Tuning
 

Another little know reality is the worthlessness of the oil cooler system. There is a thermostat like device that prevents any meaningfull oil being circulated through the cooler until the oil gets to over 240+ deg. by then it is really too late to help. So if you are looking to address cooling the oil you have to do something about this 'thermostat' first.

Tyler

Re: WOT Tuning
 

Tyler,

Please keep those little nuggets coming. =D>

Re: WOT Tuning
 

how would one change the opening temp of the thermastate (oil)

Re: WOT Tuning
 

Tyler,

What if the oil thermostate was removed, would that be too much cooling? As prviouly asked how can the opening temperature be changed?

Thanks,
Jerry
93 White ZR1

Re: WOT Tuning
 

If you remove the water t stat the water will not be in the radiator long enough to cool thats why you cut the spring and leave it in the system. The only down side is that when the outside temp is below about 65 deg the system runs so cool that it never goes into closed loop. Lane kept a piece of cardboard to block the radiator when it was too cold.

I know of no one that has removed the 'oil temperature control valve'. If you look in the service manual 6A2-37 at the breakout for the oil filter housing you can see its location. I have a email to Geoff about where get different value valves. It looks to me that one should be able to replace it without too much trouble.

Tyler

Re: WOT Tuning
 

Per Geoff Jeal ex Lotus calibrations engineer for the LT 5 engine.

Quote

As far as I know there is no alternative wax capsule for this application, you can however remove the wax stat and jack the shuttle valve open. This is how all of the dyno engines were run during development.

Unquote.

Tyler

Re: WOT Tuning
 

Tyler,

Thanks for posting the reply from Geoff. Any thoughts on what the oil temp would be if the valve was open all the time. Past posts stated that we don't have a problem with oil temp unless it's 300F, that temp troubles me. I have a Ron Davis Rad. with a 180F thermo., when doing track events at both Portland and Thunder Hill in Northern Ca. my oil temp will go to 240-250F when the car is being pushed, I back off when I see 250F. I still would like the oil cooler in the loop at all times. Am I being too conservative?

Thanks again,
Jerry

Re: WOT Tuning
 

Do not know anyone who has done the mod but if they were doing it on the dyno motors it must have helped stabilize the temp where the wanted it to be. If your oil is going that high your water must be really hot. Not sure what the stock oil cooling system would do after doing the above but if I went to the trouble to mod it as above I would add a cooler rather than use the stock setup unless you do the bypass mod above. In stock form the water temps are still high and since the oil cooling is so close to the radiator I would be concerned that it is not getting as cool as needed.

Tyler

Re: WOT Tuning
 

Best solution then would be to eliminate the thermostat. I've done that in the race car, but it does not see much cold temp operation unless it's a nice day and i take it out on the streets to cycle everything. But I let it get real hot by cutting off the cooling fans.

Re: WOT Tuning
 

So I have a question? In the winter when air cooling is at its max, the temp should hover around where the thermostat device opens, right? My car in the winter will generally have an oil temp around 180-185F in street driving. I assumed from that that the oil thermostat begins circulating oil at that point? Am I thinking about it wrong?

Re: WOT Tuning
 

What is the purpose of the Oil thermo., could it be for those folks in the mid west and eastern states that have those misable winters? Most folks that have a car that is driven hard install "oil coolers", yet they don't have thermostats, so why is there one on the ZR1?

Will be inspecting my cooling system thermostat this week as I don't believe I should be seeing high temps with the RD radiator no matter how hard the car is driven.

Tyler keep posting those "nuggets" of info.

Thanks,
Jerry

Re: WOT Tuning
 

According to Geoff the oil cooler setup was kept to help HEAT the oil in cold climates. When they did cold weather testing the proxmity of the cooler to the radiator and the minimal flow helped the car come up to temp faster thus pass the emission testing. With the high thermo opening it was not really designed as a functional oil cooler.

Tyler

Re: WOT Tuning
 

Tyler,

Thanks for the reply. I am still confused on the water bypass around the rad.; if the spring is cut why would you have to plug the bypass if the thermostat is what sends the water thru the bypass?

Jerry

Re: WOT Tuning
 

Jeff,

Where did you get a 170F thermostat, I find only 180F and of course the $100plus 160F?

Jerry

Re: WOT Tuning
 

I ran mine both ways. I started without pluging the bypass then ran it with a plug to see if there would be any difference. I did not notice any difference but left it in to make sure there was no hot water leakage around the radiator.

Tyler

Re: WOT Tuning
 

randy woods he also sellls the under drive pullies . he also has a 165 therm that lets our cars run right at 180 . i got that one and love it . the 160 doesnt let the car go into closed loop.hes under specilized racing products . hope this helps

Re: WOT Tuning
 

John,
Do you have a web site address for Randy Woods?

Tyler,

If I cut the thermostat spring as indicated in the picture you posted will it allow for bypassing the Rad. when it's cold? I think I understand how it works at high RPM and thus cutting the spring will get rid of that problem but what about warm up, the water needs to go somewhere when the thermo is in the closed position?

Jerry

Re: WOT Tuning
 

go on the links page on the registry and find specialized racing products click that and your home :cheers:

Re: WOT Tuning
 

Cutting the heavy spring opens the thermo all the time as you are cutting the spring that opens the water flow as the water warms up. IE In the stock configuration when cold the bypass is opened by pressure because the main water route is plugged. As the water flows down the bypass it warms the thermo and it opens to allow flow through the radiator. This drop in pressure closes the bypass and forces water through the radiator until it is opened by pressure brought about by the increased rpms. I also think this design increases the failure rate of the water pumps.

Tyler

Re: WOT Tuning
 

Tyler,

If I read your reply correctly it seems to me that one could "plug" the bypass line and remove the thermostat?

Thanks,
Jerry