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Initial tuning results for TEC3/GT42R...


TimZ

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Hi Tim,

 

If you ever get tired of you L6, I'll buy it to power my SR71. OK, I'll take a stab at the high EGT's. Could you have too much restriction in your 1 and 2 cylinder exhaust runners? It looks like they merge into one 2" pipe. Considering you're flowing more fhp through those two cylinders alone than my whole engine, I'd speculate this restriction could cause a backup to your intake manifold as well as create high egt's/boost creep. This might explain why your high egt's look PR independent because your turbo/wastegate might not be the bottleneck. Does the creep start at a particular mass flow rate? If there is a header/exhaust port restriction, I would guess that creep would start at a higher rpm for a lower PR.

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Gotcha. For some reason I assumed the 630HP was crank HP. I've thought of running full sequential with my Tec3 and one option I have found was a cam timing sensor that Ron Tyler (on this forum) made for a friends car. He basically fabricated a distributer like device in place of the factory distributer for the cam timing them used individual coils mounted on a bracket right next to the spark plugs. If I remember correctly the SP wired were about 2" long.

 

Now I got to get back to work myself....:icon11:

 

I just took a factory electronic distributor, locked down the mechanical and vacuum advance mechanisms, and ground off all but one of the teeth on the reluctor. The factory pickup works just fine with the TEC3.

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I just took a factory electronic distributor, locked down the mechanical and vacuum advance mechanisms, and ground off all but one of the teeth on the reluctor. The factory pickup works just fine with the TEC3.

 

 

Both of those are good ideas, thanks! We will need a cam position sensor when we use the ECU882 system on our engine, and that "single tooth" conversion sounds easier than what I was thinking about doing.

 

Matter of fact, both ideas sound easier than what I was thinking of doing.

 

I am glad someone has more common sense than me on some of this fabricated stuff! LOL

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Both of those are good ideas, thanks! We will need a cam position sensor when we use the ECU882 system on our engine, and that "single tooth" conversion sounds easier than what I was thinking about doing.

 

Matter of fact, both ideas sound easier than what I was thinking of doing.

 

I am glad someone has more common sense than me on some of this fabricated stuff! LOL

 

Glad I could help, Tony - I'm happy to see that you found this thread!

I think that the mods I did to the stock distributor took me about an hour to complete - so that was really an easy way to get the cam sensor function. The TEC3 only requires you to be within something like 40 degrees for the full sequential function to work, so the extra scatter from the distributor drive is irrelevant.

The most time consuming part of this mod mostly involved taking care of the aesthetics - I tapped the hole for the vacuum advance dashpot for a 3/8" npt plug, and then I cut down a distributor cap and filled the holes with JB weld in order to make it like it was meant to be that way.

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Tim, I love the simplicity... great idea!

 

Mr. Kurzahls if referring to this scratchbuilt 'cam' sensor, utilizing the stock distributor shaft (no crank sensor needed)...

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hintzcamsensor.jpg

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John, I ended up using longer wire's than originally planned...

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coils.jpg

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James Thagard talked me into the turbo, but I was skeptical - it just seemed too optimistic. It does take it a bit longer to come on, but when it does, DAMN! :mrgreen:

I remember the conversation.

 

James: Hey Tim, do you want a GT42R? It will allow you to make more power and the spool should be the same.

Tim: OK:)

 

When we discussed this turbo we speculated it making 575-600hp with the turbo swap. I guess that number is out the window!

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I remember the conversation.

 

James: Hey Tim, do you want a GT42R? It will allow you to make more power and the spool should be the same.

Tim: OK:)

 

When we discussed this turbo we speculated it making 575-600hp with the turbo swap. I guess that number is out the window!

 

:mrgreen:

Okay - so I was skeptical, but not so much that I wasn't going to try it...

 

I think there was at least one "are you sure?" in there before the "OK".

;)

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Yeah, Ron, we had formerly used the TEC2, and had the Electromotive "small" crank fire wheel installed on our distributor like the setup you showed. I think it's far more practical for cam sensing. They said on the TEC2 it would not be reliable over 8500rpm, and they were right! So since the TEC2 used that damnable $300 O2 sensor, and we needed both a sensor AND to reinsall another balancer to get the accurate Crankfire sensor off the crankshaft, we converted to the ECU882 Setup. The dissy is plugges, but on the N/A L20A we are not using the Sequential feature, for the Turbo as Tim is surmising, we will probably be better off with some bigger injectors and sequential injection.

 

Bravo on the Coil installation "Great Minds Think Alike" is all I can say! LOL

Those coils look a lot like the units we got from Lance for the ECU882 Setup.

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They said on the TEC2 it would not be reliable over 8500rpm, and they were right!

 

Probably becuase of the close proximity of the sync. tooth?

 

we converted to the ECU882 Setup.

 

I would really appreciate an unbiased opinion of the 882. This thread isn't the place for it though. If you get around to it, can you PM or email me your opinion, likes & dislikes?

 

ron@primeems.com

 

Bravo on the Coil installation "Great Minds Think Alike" is all I can say! LOL

Those coils look a lot like the units we got from Lance for the ECU882 Setup.

 

:-D

 

I'll find out in a couple weeks what I think of them. You like them so far?

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  • 5 months later...

Now that the weather is coming around, I've been able to start the dialing in process. Here's a bit of confirmation of my suspicions...

TIP.jpg

 

I instrumented the turbine inlet pressure and datalogged it along with everything else. It appears that at ~24psi manifold pressure, I'm seeing anywhere from 16 to 20psi TIP (!).

 

Exhaust temps are still running a bit high, but damn it's pulling strong... :mrgreen:

 

Tony D (or anybody) - any insight on tuning strategies?

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Tim, With ~24psi manifold pressure shouldn't you see the same or higher turbine inlet pressure? Unless I'm reading this wrong you literally have a negative backpressure.

 

Regarding the high EGT's, the only other options besides AFR's and timing I can think of would be to run E85 or install water/methanol injection. This is a stretch but maybe the turbo cam profile is contributing to the higher temps. If the exhaust valve opens too early you might get the symptoms you are experiencing.

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Tim, With ~24psi manifold pressure shouldn't you see the same or higher turbine inlet pressure? Unless I'm reading this wrong you literally have a negative backpressure.

 

Regarding the high EGT's, the only other options besides AFR's and timing I can think of would be to run E85 or install water/methanol injection. This is a stretch but maybe the turbo cam profile is contributing to the higher temps. If the exhaust valve opens too early you might get the symptoms you are experiencing.

 

You were reading correctly - I literally have less pressure in the exhaust manifold than in the intake. This is not a situation that I am used to having. I've been thinking about retarding the cam timing, but haven't gotten to it just yet - hopefully this weekend. The thinking behind this is that keeping the exhaust valve closed longer will result in more energy being used in the power stroke, thus lower EGT when it does open.

 

So far, I've found that I can keep the EGTs down to ~1600F by running a really rich mixture (~10:1), but that is killing the power. I've found that "leaning" the mixture out to ~11.5:1 adds a considerable amount of power, but the EGTs go back up. Also, I've found that adding timing has helped to an extent, but I'm not too comfortable with advancing any farther than where I currently have it.

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I always like you writeups Timz, they are so informative. I may be able to help you out with some of your questions.

 

First we will tackle you EGT numbers, yes probe placement can have a effect on the numbers you get, and also guage calibration. When you get above 500F some of the gas laws, and themodynamics start getting tricky. There is conduction, convection, and radiation now when the gasses get hot. The probes visual line to the glowing gas has an effect on the reading.

 

Second is the pressure ratio of your turbo. Your boost limit is dependant on how much you can push through your dowpipe.

 

Think of your downpipe as a straw. The outside air is 1bar. Now with your old setup turbine pressure was 4bar (for example), so that would be like blowing on the straw with 4bar. This means there is a differential pressure of 3 bar. This will give you a certian flow through the staw. Now with the new setup you are blowing with 2bar pressure turbine pressure. This will have a differential pressure of 1bar, there will be less air flow throuh the straw with your new setup. (It is a little more complicated than that, temperature will actually play a factor).

 

This is why with your new more effiecient setup, you need a bigger wastegate.

 

 

Next I would like to open up the disscusion on ignition timing on EGT, I think for most ballpark situations that less timing = less egt, more timing = more EGT. There comes a point where you retard timing so much that the combustion happens in the exhaust giving you high EGT's. This is how rally cars spool there turbo's off the line (anti-lag). It can cause a turbo explosion if not done properly, and in general reduces the life of the turbo.

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You really should look into E85. A local supra guy is making killer power on it with a stock longblock and a gt4276r. He pushed it to 30psi on E85 with methanol injection.

 

http://www.supraforums.com/forum/showthread.php?t=427200

 

Heres a dyno chart at 24psi on straight E85:

http://www.rrevmotorsports.com/public/e85.bmp

 

Heres a dyno chart at 30psi on E85 + methanol injection(He says he could have run this boost on straight 85, but he added methanol as a safety margin since this is a completely stock longblock):

http://www.rrevmotorsports.com/public/e85meth.bmp

 

Regards,

Justin

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Guest speedy1003

Hi Timz. I don't stop here by much, but found this post when researching my own "higher than normal" EGT issues on my 91 TTZ.

 

I am running JWT 400 cams in my VG, and I noticed they build in 4 degrees of advance in the exhaust side. Prior to degreeing these cams, I found that my exhaust timing was retarded by approx 4 degrees on the pass side, and about 8 degrees on the driver's side. I think you posted similar results on tt.net some time ago. Well, when I degreed my cams, I built in the 4 degrees of exhaust-side advance...to make these cams match what JWT intended.

 

Result = MUCH higher EGTs. Running 11.5 afr / conservative timing / Sunoco 94 octane and 15psi, it's nothing to see my EGTs shoot to 850C. I'm still dialing in my tune, but as the tune sits now, there isn't much wrong with it...just needs a little tweaking here and there. I'm in your boat - scared to go too high on timing, and just hate the thought of running pig rich just to cure the problem.

 

Prior to degreeing my cams, my EGTs were fairly normal. It took running a race tune with C16 at 25psi to even come close to 900C. I am leaning towards the fact that buiding in the 4 degrees of exhaust cam advance is the culprit to my high EGTs. Based on the latest comments in this thread, sounds like that might very well be the case.

 

I know we're not talking apples to apples on engines, but if you have any thoughts on my scenario beyond what I listed, I'd love to hear them.

 

Regards,

James

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I was in Detroit on Monday and spent some time with Tim and his family. I had an opportunity to ride in the car before the rain came and it is fast. First and second gear were useless once boost hit, but we were able to get a few good pulls in 3rd gear on the street. The car pulls very hard in 3rd so I don't think the numbers he posted are too far off.

 

The setup is exceptionally clean and the detail in Tim's setup is apparent as everything has a place and purpose. However, at this point there is not too much more room for anything else.

 

Thanks for you hospitality and the ride:)

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I was in Detroit on Monday and spent some time with Tim and his family. I had an opportunity to ride in the car before the rain came and it is fast. First and second gear were useless once boost hit, but we were able to get a few good pulls in 3rd gear on the street. The car pulls very hard in 3rd so I don't think the numbers he posted are too far off.

 

The setup is exceptionally clean and the detail in Tim's setup is apparent as everything has a place and purpose. However, at this point there is not too much more room for anything else.

 

Thanks for you hospitality and the ride:)

 

 

Tim's car has always been an inspiration for me ....

 

When you going to be down my way James ?? :burnout:

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