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Discussion Starter · #1 ·
Gave up on TH200s and made the switch to a TH400 with a Pat's 9" converter. Engine and tranny performed great but the converter is too tight making the car a bit of a slug up to about 150', then it flies.

1.624, 6.815 @ 105.83, 10.531 @ 132.08. Left with 2# (foot to the floor) and saw 25.2# through the traps on the datalogger. The 1/8-mile time factors out to a 10.70 1/4-mile. 3.716 between the 1/8 and 1/4 is the quickest the car has ever gone and factors out to about a 10.29. Last time I ran the car it cut a 1.52 and that 60' would have netted me a 10.38 or better, backing up the quick 2nd half numbers. Restalling the converter and a couple more psi should lay down some decent numbers. BTW, that 3.716 is only .036 slower than the Z when it went 10.087 but the Z cut a 1.36 and was quick to the 1/8-mile with a 6.407. RX7 will never match the Z off the line with the stock IRS and being 250# heavier, but I am stoked at the potential.

The myth that the TH400 is heavier has been layed to rest and if it is robbing the engine of so much power, we probably ought to let the engine know about it :D :D
 

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Congrats on getting the change done, I finally got mine to track last night and I have some major trans or convertor issues to deal with. What were your RPM's through the traps ? I was at 6400 rpm at 119 mph in third gear with a 3.07 rear which is a sick ammount of slippage, I am getting sick of trying to make this 200 work my self.The bright side was a no boost launch yielded a 1.50 sixty and a 1# launch spun bad.
 

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Discussion Starter · #3 ·
I assumed you had 26" tires and not locking up and that factors out to 32% :eek: Definitely something seriously wrong.

My datalog shows 5590 @ 132. I am also running the 3.07s with 27x10.5x16 ET Streets which I guess grows about .25". That factors out to about 9.4% which I can live with as it gives me some room to hit 137+ @ 5800. Before I pull the converter I am going to fine tune the TEC for less fuel/more timing in the RPM and MAP ranges where I am trying to stall and also be a little more aggressive on the loud pedal when I stage. That might be what I need to get back to cutting lo-1.50s or better.
 

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I realize our combo's are very different but with your converter what kind of rpm do you see on the power brake before you get boost, I have no boost at 3000 rpm and see about 1# at 3600 rpm and 2-3 # at 4000 rpm which is about all I can hold on the footbrake before the car pushes, When I launch I see a instant 18# boost and 5000 rpm. My first pass was a dry hop of the tires(MT235/60/15 DR) with no smoke a 3000 rpm launch and every time I looked at the tach I was at 6500 rpm. I went a [email protected] with a 1.50 sixty. My next pass I tried coming out at 1# boost but it spun hard and I let off shifted second and locked the converter, wound second to 5800 and let off to shift third wound that to 5800 and shifted OD which dropped the revs to 5200 and it went another 10.90 but at 126 with a 1.70 sixty. still very low mph for the rpm with a locked converter. I wonder if forward clutches can slip that bad without total failure ?
 

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that rear end must be holding up good, how much of a hassell was it putting it in the car and what was the cost ? i've got to get mine to the track as soon as i get the head gasket problem fixed. mine has a bunch of blow bye when it's under boost and the motor is new, so i guess after 2 years i will have to pull it out, if i could get mine running somewhere near to that one of yours i would be happy. i think i can but in order to d that i will have to get out in the heat and work on it, i'm sure you know what i'm talking about. congrats on the new trans. ted :headbang:
 

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Discussion Starter · #7 ·
If the car is pushing through the footbrake, use the handbrake. That is what I do and it works great once you get the technique down.

Spent some time studying the datalog and discovered something that might be a part of my problem. I am using an aux rev limit feature to control launch RPM. It is activated by grounding the MAT. Since I use the handbrake, I put a momentary switch on the handle to ground the MAT when I pull up the handle. This should allow me to put my foot to the floor but have the RPMs limited to 3500 (my setting). Turns out that when I ground the MAT, it outputs 266*F and the ECM automatically pulls timing because of the "high temps". Trying to figure out if I have a bad MAT or that high temp output is normal when the MAT is grounded. I am also getting enough knock at the same time to also pull a little timing. Pulling timing is the opposite of what I need at that point. Once I relase the handbrake, I imagine it takes a little time to return to normal. From that point on it runs knock-free and the MAT drops to about 86*F in the traps. Temp was in the 90s yesterday. I AM AN ALKY(control) :alcohol: :D :D

The stock IRS with the C4 diff is not strong enough for a t-brake, IMO, so I would not try it.
 

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Scottie-GNZ said:
It is activated by grounding the MAT. Since I use the handbrake, I put a momentary switch on the handle to ground the MAT when I pull up the handle. This should allow me to put my foot to the floor but have the RPMs limited to 3500 (my setting). Turns out that when I ground the MAT, it outputs 266*F and the ECM automatically pulls timing because of the "high temps". Trying to figure out if I have a bad MAT or that high temp output is normal when the MAT is grounded. I am also getting enough knock at the same time to also pull a little timing. Pulling timing is the opposite of what I need at that point. Once I relase the handbrake, I imagine it takes a little time to return to normal.
What ecm are you using that does that?.
Grounding the MAT sure seems like an odd way to set *Launch Mode*.

Pulling timing (assuming the code is done correctly), is a perfectly fine way of limiting the launch RPM. The crank sensor is looked at (polled) very frequently, and the return to normal timing should only take one crank trigger event or 2 at the most to return to normal.

You might try finding a faster reacting switch then the handbrake..
 

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Discussion Starter · #10 ·
Doc1of7 said:
What ecm are you using that does that?.
Grounding the MAT sure seems like an odd way to set *Launch Mode*.

Pulling timing (assuming the code is done correctly), is a perfectly fine way of limiting the launch RPM. The crank sensor is looked at (polled) very frequently, and the return to normal timing should only take one crank trigger event or 2 at the most to return to normal.

You might try finding a faster reacting switch then the handbrake..
I am not using one of the "standard" TR engine management systems. It is an Electromotive TEC2 and using the MAT is simply a way to send a signal to the ECM. You are correct that the ECM returns timing to normal rather quickly but the issue is not the handbrake or a slow reacting switch. Once the turbo loses momemtum, it takes a moment for it to spool back up, especially when exhaust energy is that low. I simply forgot something in the configuration.
 

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Discussion Starter · #14 ·
Got the converter restalled by Steve at Pat's Converter and he nailed it!

1.458, 6.522 @ 107.71, 10.174 @ 134.50. That was with 27psi and a myriad of nitpicking problem. It was another mid-90s muggy day in Orlando and on the way to the track the 50A fuse for the Taurus fan melted the fuse holder and it pegged the 240* temp gauge before I could pull over and address it. Rigged it up so I could run on the low-speed and was concerned if it did any damage. Still not 100% sure. On the 10.17 pass I went through the traps at almost 210* but the MAT (measured at the upper plenum) was 107*. ALKY RULES!!! My shift lite also crapped out so I was guessing on the shifts and the 1-2 was at 5360 and the 2-3 at 5500!

The tune appears to be dead-on so I plan to bump it up to 28psi and enjoy it, but 1st I need to fix a few things.
 

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Discussion Starter · #16 · (Edited)
The car has a 6-pt rollbar with a DS swingout. It weighs in right at 3000# with me depending on how close it is to a holiday :D :D

Remember I just switched to a TH400 and this was the first time to the track with a restalled converter so I am still experimenting. On that pass I brought up to about 7psi then eased it to the floor as the lights counted down. Do not know exactly how much I left with but I plan to study the datalog and fully understand and try to make it repeatable.

BTW, there has been so much talk about how a TH400 saps HP and if that is really so I will make sure my engine does not know about it :D For the folks considering the 4.1L budget buildup, this equates to about 560rwhp based on a 1/4-mile formula. Should be enough to push a 3700# sled to a 10.80 and quicker in cooler weather.
 

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bad boy

You are really getting me fired up to get busy on mine. i guess the most practial thing for me to do is to get the blue car going. i have a pretty slick garage kept 86 hard top with manuel windows in it and i think it will be the lightest one of all 3, the interior in it looks like yours. so i guess the next thing is to get the motor out of the gold one and it get it apart and see where the blow bye is coming from. congrats on the times and it looks like you will be seeing the 9's real soon. ted ps; where did the roll bar come from ? a kit or did you have someone do it ?
 

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Discussion Starter · #18 ·
I am not obsessed with running 9s but it looks achievable.

The rollbar was built by a buddy at his shop, Mazworx. First one they did for an FC and there is no kit but it can certainly be duplicated. They do incredible work.

http://www.mazworx.com
 

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Scottie, congrats again. I'm still chuckling over the expressions on people's faces and their puzzled looks walking away after seeing the pass and inspecting the little v-6 under the hood. That alone was very entertaining!
The best part is that the car has much more in it!
p.s. Don't let your turbo 400 tell my turbo 400 it's supposed to slow my car down. SHhhhh! LOL.
 

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Looks great Scottie and that MPH is awesome! Good 60' too!

I think that a 9.9x is inevitable with better weather and little more boost. :6:
 
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