Questions from the track.

[turbojimmy]

Hi all,

The past few years I've been whining about hitting a performance 'wall' at around 114-115 MPH. This year I've added a T70 turbo and headers hoping maybe to get beyond 115 MPH. The car 'feels' stronger - at least throttle response is better. I headed out to the track last night and got essentially the same timeslips I've been getting for about 4 years now. High 11s at around 113-114 MPH. I'm not running a lot of boost - around 23 PSI - and I know I need to crank it up in order to go faster (and to make best use of the T70) but I think some of my numbers show that I'm pretty close to peaked out so I'm looking for opinions (and have some other questions). I have the mods to get me into the 10s so I guess it's a matter of tuning?

First, my (narrowband) O2s start at 850 and get down to 805 at the end of the run. Seems to me that this is pretty good - maybe a little fat. EGTs are high-1500s, low-1600s. Given this it doesn't it seem like I don't really have room for another 4-5 PSI? I'm running 27/25 timing and C116 fuel. I can probably get away with 29/27 or 29 flat out.

Second, how much range should I be able to get out of a HD actuator? Last night I was trying to get more boost out of the T70 and just couldn't. I'm using an HD actuator and a simple bleeder for boost control. It seems my range is like 3 or 4 PSI. I've got the rod pretty tight and only saw about 23-24 PSI with the bleeder wide open. If I close the bleeder completely I have like 20 PSI.

Third (more of a curiousity), what does the MAT reading have to do with anything? Since I made my MAF 'blow-thru' I now have the air filter (and thus MAT sensor) under the hood rather than behind the bumper. MAT temps were 100+ on a high-30 degree ambient temp night. I'm used to seeing MAT temps that reflect ambient temps but I don't know if it really matters.

Fourth, the good news is that I'm picking up more MPH between the 1/8th and 1/4 than I ever have. I'm getting like 22-24 MPH from the 1/8th to the end of the 1/4 - used to get 20-21. But I'm way down in the 1/8th. I've gone from a best of 96 MPH in the 1/8th to 89-90 MPH. I put a new Vigilante converter in the car last year that I thought might be slowing me down but looking at the RPM and shift points it's almost identical to my old 9x11 (except that it actually locks under WOT). It keeps the engine operating in the 4900-5500 RPM range the length of the track. Is this too tight? How does one measure converter efficiency (I've seen the term but I don't know how to calculate it)?

Fifth, and related to the converter question above, my chip locks the converter at 90 MPH. Would I gain anything by locking it earlier? Looking at the RPM and MPH plot you can barely see where it locks which makes me think I may benefit from locking it earlier? I don't want to bog it down, but if I'm locking it at a point where it's already coupled pretty good what good does it do?

I guess that's it - sorry for the long post. I think it was a decent first run of the season. Even though it was Friday the 13th I did have a bit of good luck in that I didn't set my car on fire. I drained the 93 out of the tank and added the C116 and forgot to hook the fuel pressure gauge back up to the rail. Closed the hood, cranked it over. Nothing. Cranked some more nothing. Smelled gas. Popped the hood and there was C116 EVERYWHERE. I let it air out for about 15 mins and ran it. Unfortunately EVERYTHING still smells like fuel: the interior, under the hood, me, the garage, etc. Hopefully it will air out. On the positive side C116 makes an excellent (albeit expensive) degreaser.

Jim

 

[Chuck Leeper]

My $.02...

1.I'd be doing some checking with a WB, and see what the fueling really is.
2. What does the rpm do at the shift points? If the engine goes to max rpm, and doesn't pull back on the shifts, the converter could be too loose?
3. Have you done the math to see if the verter is slipping, even tho it's supposed to be locked? 3.42 gear,115mph,1:1[3rd gear], locked,28" tire = 4719RPM. That raises the ?? Is it really locked?[Assuming the input values are correct].
4. EGT's over 1600, are a ??
5. RWHP shows to be 427. The Et is 11.8+, and the MPH shows to be 115. I used a race wt of 3600#.
A loss on the short time, and the 1/8th, may indicate a verter is??

MAT input can trim the fuel. Maybe extend the cable, and put it in the intake plenum, to get realtime reporting of intake temps?

 

[turbojimmy]

1.I'd be doing some checking with a WB, and see what the fueling really is.
2. What does the rpm do at the shift points? If the engine goes to max rpm, and doesn't pull back on the shifts, the converter could be too loose?
3. Have you done the math to see if the verter is slipping, even tho it's supposed to be locked? 3.42 gear,115mph,1:1[3rd gear], locked,28" tire = 4719RPM. That raises the ?? Is it really locked?[Assuming the input values are correct].
4. EGT's over 1600, are a ??
5. RWHP shows to be 427. The Et is 11.8+, and the MPH shows to be 115. I used a race wt of 3600#.
A loss on the short time, and the 1/8th, may indicate a verter is??

MAT input can trim the fuel. Maybe extend the cable, and put it in the intake plenum, to get realtime reporting of intake temps?

Thanks Chuck!

I think the RPMs on the shifts are fine. I put together some charts here:
http://turbojimmy.4t.com/041307_runs.htm

What concerns me a little is that I also have a chart from 2004 when I ran my best MPH (117 and change). The RPM with the 9x11 locked is less than the Vigilante locked which makes me think that the 'locked' Vigilante may be slipping a little? The difference is only a couple of hundred RPM. I'm pretty sure I'm running the same tires, but I'm not 100% sure. Definitely the same size tires (275/60s) but height might vary slightly between manufacturers.

The converter math makes sense - I'll have to noodle that through. The MPH I get from DS is not accurate because I'm running a 28" tall tire but I can adjust for that.

Jim

 

[norbs]

From your datalog, your pulse width calculation, it shows you are close to 85+% duty cycle. This means you are supplying enough fuel to support 460 rwhp. What is the weight of your vehicle? From this we can see what mph you should be running. The T70 you should be atl east 122-124 mph on that set up. You are probably running too rich, losing 50 hp. But without wide band your o2 readings could mean anything from 10.0-14.0. Get the innovate lm-1 on this thing and tune it to 11.3-6

 

[TurboDave]

Thanks Chuck!

I think the RPMs on the shifts are fine. I put together some charts here:
http://turbojimmy.4t.com/041307_runs.htm

What concerns me a little is that I also have a chart from 2004 when I ran my best MPH (117 and change). The RPM with the 9x11 locked is less than the Vigilante locked which makes me think that the 'locked' Vigilante may be slipping a little? The difference is only a couple of hundred RPM. I'm pretty sure I'm running the same tires, but I'm not 100% sure. Definitely the same size tires (275/60s) but height might vary slightly between manufacturers.

The converter math makes sense - I'll have to noodle that through. The MPH I get from DS is not accurate because I'm running a 28" tall tire but I can adjust for that.

Jim

From that chart, it appears as though the converter clutch is slipping BADLY!!! It appears to be locking around frame 160 and the rpm keeps dropping into frame 175 or so. A very slow sloppy lock. I've got better traces than that way back when I was locking my stock converter. Your clutch is very likely shot.
And unless it's a multi disc I would NOT recommend WOT locks. Not on any single disc, regardless of what you've been told. You need a multi disc to do WOT locks and expect it to perform/lock and stay not slip.
Your rpm drop with a multi disc WOT lockup should actually be sharper than the rpm drop at the shifts (by a lot).

 

[norbs]

Or the tranny could be slipping in 3rd or a combination of both. But you need to get the motor dialed in then go after one thing at a time. The lockup is very hard on the direct clutches also. You shift into 3rd gear at 60 mph and your rpm is over 5000 rpm? The calculated rpm for 3rd gear at even 65 mph should be 2700 rpm about. Seems you converter/tranny is keeping the motor at 5k it should drop right after the shift. If you locked it up it should be at least under 4k at that speed.

 

[turbojimmy]

The trans is a new (Sep 2006) CK Performance trans and the converter is a new (Sep 2006) Vigilante 5-disk converter. I thought the car slowed down a bit when I moved to that converter. I replaced a 9x11 with it that had a cracked stator and also wasn't locking anymore.

The car is a full-weight GN - I figure 3600 lbs with Mototron injectors.. I might go weigh it today, actually, just for fun. I need to head over toward the salvage yard on an errand anyway.

Thanks all for the replies thus far.

Jim

 

[turbojimmy]

Or the tranny could be slipping in 3rd or a combination of both. But you need to get the motor dialed in then go after one thing at a time. The lockup is very hard on the direct clutches also. You shift into 3rd gear at 60 mph and your rpm is over 5000 rpm? The calculated rpm for 3rd gear at even 65 mph should be 2700 rpm about. Seems you converter/tranny is keeping the motor at 5k it should drop right after the shift. If you locked it up it should be at least under 4k at that speed.

Yes - it's shifting to 3rd @ 5400 RPM. I'm not locking until 90 MPH though. If I locked it in 2nd gear I suspect it would be closer to the 2700 RPM. It drops about 500 RPM after each shift, unlocked.

I think it is running rich, too. Chart 2 is when I forgot to shut off my alky. Since I was running C116 I didn't need the alky. Run 3 is after I shut the alky off - I picked up 1.5 MPH in the 1/4 and after spinning for like half the track (in Chart 3 you can see where it finally grabbed). The track was very slippery last night. I know typically MPH isn't affected by traction much, but it was terrible. Run 14 could've been a 117-118 MPH run but I had no traction off the line - I actually thought I broke something because it felt like the engine wasn't connected to the trans. I let up and tried to let it grab a couple of times and finally got moving. My 60' time was 2.7. The guy was mopping something up as I staged - I should have known.

So why would a new Vigilante 5-disk not be locking up properly? Chris uses the better solenoid in his transmissions and he installed the funky plumbing that came with the converter. Or is it because I'm locking at 90 MPH? Would it be better (and quicker) if I locked as soon as it shifted to 2nd?

Thanks,
Jim

 

[TURBO 6]

When I had a multi disk I would activate the switch after I did my burnout. Why have a multi disk if you are gonna lock it at 90 mph?? Let it lock as soon as it hits second gear. That's 2 mph right there.

 

[turbojimmy]

When I had a multi disk I would activate the switch after I did my burnout. Why have a multi disk if you are gonna lock it at 90 mph??

I dunno - never thought about it. I'll have to try that next time out.

I had the car weighed - 3,540 lbs. w/out me in it. 3,740 (give or take) with me in it. Using an online calculator, that's 440 at the wheels which is a bit off given the injector duty cycle, correct?

I'll have to run more boost to lean it out a little - I still have not gone beyond 24-25 PSI with it.

Jim

 

[TurboDave]

When I had a multi disk I would activate the switch after I did my burnout. Why have a multi disk if you are gonna lock it at 90 mph?? Let it lock as soon as it hits second gear. That's 2 mph right there.

Because some of us don't make enough HP to lock it that low. After a couple of years of testing and beating on mine, I found that after going through all the data, that the car didn't run near as fast locking it when second gear hits as apposed to locking it after the 2-3 shift. It all has to do with where the car is making it's power. The 1-2 shift bog (rpm dropped way down out of the power curve) was just too much drag to overcome for my measly 450HP motor.

 

[norbs]

There should be a huge drop on the lockup, even at 90 mph you should be at 3700 rpm. If you lock at 60 mph the car will bog and go slower. I found its best to lockup above 85 mph minimum,or it will bog. If it doesnt drop at least 1000 rpm then its not working or slipping away.

 

[TurboDave]

There should be a huge drop on the lockup, even at 90 mph you should be at 3700 rpm. If you lock at 60 mph the car will bog and go slower. I found its best to lockup above 85 mph minimum,or it will bog. If it doesnt drop at least 1000 rpm then its not working or slipping away.

That's why I now have my chip set to lock it at 88mph. It seemed to be the optimum speed, and yielded my consistently highest 117.5mph runs.

 

[turbojimmy]

There should be a huge drop on the lockup, even at 90 mph you should be at 3700 rpm. If you lock at 60 mph the car will bog and go slower. I found its best to lockup above 85 mph minimum,or it will bog. If it doesnt drop at least 1000 rpm then its not working or slipping away.

Yes, you're right. Looking at the data I'm not really getting much of a drop at all. 100-200 RPM tops. Of course I can't lock it at 90 MPH manually when I'm not at the track, but it will lock hard and bog at WOT at highway speeds. Strange.

I'll have to try locking it manually at the track but I doubt it will be any different. It's doing something as evidenced by the slight RPM drop when it calls for the TCC lockup.

Jim

 

[turbojimmy]

But without wide band your o2 readings could mean anything from 10.0-14.0. Get the innovate lm-1 on this thing and tune it to 11.3-6

So if I go wideband, can I replace the stock O2 sensor or do I need another bung welded in? I already have my 'extra' bung consumed with the EGT probe.

Thanks,
Jim

 

[Nojug]

how new are the valve springs?

 

[TurboDave]

So if I go wideband, can I replace the stock O2 sensor or do I need another bung welded in? I already have my 'extra' bung consumed with the EGT probe.

Thanks,
Jim

You can't run a wideband sensor in the stock location. To much pressure and heat!!!!! It needs to be in the downpipe, or anywhere at least 10-12' downstream of the turbo.

 

[norbs]

Dave is correct, and if you have alky don't use it until you get everything else sorted out and the a/f perfect. Once you throw alky in the equation the a/f now has to be tuned richer, depending on how much you spraying, which makes it harder to tune.

 

[turbojimmy]

Dave is correct, and if you have alky don't use it until you get everything else sorted out and the a/f perfect. Once you throw alky in the equation the a/f now has to be tuned richer, depending on how much you spraying, which makes it harder to tune.

I only use alky as a crutch on the street to keep from blowing the engine up. I just turn up the knob to keep the knock gauge quiet. At the track I run 116 and shut off the alky.

I ordered up an LM-1 wideband sensor. I'll have to put a bung in the DP down by the test pipe I guess. Is the wideband O2 and EGT redundant? I'm thinking if they are then I'll sell the EGT arrangement.

I'll deal with the converter once I get my 1/8th mile performance back.

EDIT: Forgot to comment on the valve springs. They're newish - probably about 8-10k miles on the rebuilt engine.

Thanks!

Jim

 

[norbs]

If your looking for an innovate rpm converter to go with your lm-1 I will sell you one a brand new spare one i bought along time ago at a great deal. The rpm converter allows you to graph rpm and any 0-5 volt inputs, like boost, and tps. The software is a very powerful tool that lets you do many neat things. Your best results for tuning are in 3rd gear always. The lm-1 very sensitive to even pickup misfires as it will show as lean spikes on your datalog. The egt should be placed right before the turbo if your is in the dp it will show 200-300 degress lower than before the turbo.