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Discussion Starter · #1 ·
Im thinking about doing this even tho some say its good and some say its bad, but everyone says its not as stressfull on the turbos and the shafts.

Its good to have TTC only if you have DP and exhaust for better flow for better results with the TTC but my question is this...

lets say you have a stock set up sequential set up and you do a 1/4 and lets say you get 13.7 and then lets say you change to TTC and would it be possible to get 13.5 or so or how much faster? (with no DP or exhaust)

now if comparing to sequestional set up and DP and exhaust to TTC and DP and exhaust then im sure the improvement in the 1/4 will be much better with the TTC, maybe in the 12s
 

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NickT916 said:
now if comparing to sequestional set up and DP and exhaust to TTC and DP and exhaust then im sure the improvement in the 1/4 will be much better with the TTC, maybe in the 12s
What?! TTC is not faster. If anything it would be slower. You lose power down low and Gain turbo Lag. Now what part of that makes you think TTC is faster???

I have the eTTC switch so I can go between Sequential and TTC anytime I want. But honestly I HATE TTC.

Please tell me why you think TTC is faster.....
 

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Discussion Starter · #3 ·
cwtt said:
What?! TTC is not faster. If anything it would be slower. You lose power down low and Gain turbo Lag. Now what part of that makes you think TTC is faster???

I have the eTTC switch so I can go between Sequential and TTC anytime I want. But honestly I HATE TTC.

Please tell me why you think TTC is faster.....
"This mod seems to provide more high rpm power (my car now easily loses traction in 2nd gear)." according to MKIV.com Since turbo #2 is not spinning when it kicks in around 4k then it takes a little time to spin to full boost and you get a boost drop when when switching with the sequential set up, but with TTC is already is spinning from start so it doesnt need that time to spool up anymore , yet giving more lag, but making a little more top end... but then again since it gives a little more at top end and lags more then it about evens out to the same 1/4 time.


what i want to know if anyone has run their car stock at the 1/4 and then did the TTC mod and did the 1/4 and saw any improvement or made it slower at the track because of the lag but felt more top end?
 

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In fact a quick search I discovered:

braddman: "TTC sucks, it Dyno'd zero horsepower higher than Sequential on my car. The lag is like a single without the power. "

Crossways: "I've run my BPU+ auto in both TTC and sequential mode (all other variables the same) on the same day at the track. The TTC runs were between 0.3-0.5 second slower. "

So people with real world experience are saying it is slower.

Show me proof that the stock turbos on the exact same boost level made more power in TTC mode then in sequential.
 

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omg, lol, nick, dont worry man, some ppl seem to get really wound up when you start mentioning ttc round here, easy as winding up a bunch of nerds at a star trek convention lol.

But na man, ttc is not faster, like he said, the bottom end lag from ttc will likely increase your 1/4 mile time. It does not make any more peak power (at the same psi), but makes for less stuff to play up, makes both turbo's lifes easier (simple fact, common sense, not arguable :rolleyes: ), and because of this, allows you to run more boost safely (without worrying about the seq system fucking something up, will give you better fuel consumption, a nice fat smooth torque curve, more predictability, and imo just feels cooler :)
 

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Discussion Starter · #6 · (Edited)
gmacrae said:
omg, lol, nick, dont worry man, some ppl seem to get really wound up when you start mentioning ttc round here, easy as winding up a bunch of nerds at a star trek convention lol.

But na man, ttc is not faster, like he said, the bottom end lag from ttc will likely increase your 1/4 mile time. It does not make any more peak power (at the same psi), but makes for less stuff to play up, makes both turbo's lifes easier (simple fact, common sense, not arguable :rolleyes: ), and because of this, allows you to run more boost safely (without worrying about the seq system fucking something up, will give you better fuel consumption, a nice fat smooth torque curve, more predictability, and imo just feels cooler :)
cooler lol... well i have talked to some people and read about it a lot and im thinking ill prob go with the TTC.

It is easier ont eh turbos and to many moving parts in the sequential set up, and boost drop at about 4k when it switches over.

Plus since ill be going with a DP and exhaust and prob FMIC then ill have no problem with the lag that it will cause and at about 400hp it will all make me happy im sure, and like you said makes both turbos lifes easier so letting the boost up a little wont hurt them at all, prob at 15psi in TTC modeis like 11psi in Seq mode... if comparing the wear and tear...
 

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NickT916 said:
coller lol... well i have talked to some people and read about it a lot and im thinking ill prob go with the TTC.

It is easier ont eh turbos and to many moving parts in the sequential set up, and boost drop at about 4k when it switches over.

Plus since ill be going with a DP and exhaust and prob FMIC then ill have no problem with the lag that it will cause and at about 400hp it will all make me happy im sure, and like you said makes both turbos lifes easier so letting the boost up a little wont hurt them at all, prob at 15psi in TTC modeis like 11psi in Seq mode... if comparing the wear and tear...
Ummm - if your sequential system is working OK now, you'll hate TTC.
"no problem with the lag"? Why not - it's not going away?
Of course, if the STTS is working poorly, you'll probably like TTC!
 

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why dont you try both and then let us know

The TTC setup shouldnt make your car any faster.
 

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Discussion Starter · #10 ·
97Tdawg said:
why dont you try both and then let us know

The TTC setup shouldnt make your car any faster.
i will do both yes... at the track ill do a sequential run and then TTC and get slips of both.
 
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you can wire TTC electrically so you can switch back and forth between sequential and TTC. listed on mkiv.com

That way you can test, I've heard that TTC is good for roadcoarse, and upper highway stuff.... thats about it. I'd just stay sequential, better low end response.
 

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I think that SEQ is a bit eaiser to get off the line on street tires, as it's eaiser to bog in TTC, BUT if you are running at least DR's and you want to luanch the car right you better be luanching at 4.5k+ at which point it doesn't matter if you are TTC or not.
TTC does make any more peak HP than SEQ, but you do gain midrange. See my old BPU dyno sheet, this was back to back pulls:


I didn't like the boost/power dip in the midrange in SEQ, which gets worse if you run high boost so I went perm. TTC and I love it. BTW I ran my best 1/4 and 60' while in TTC FWIW.
 

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gmacrae said:
omg, lol, nick, dont worry man, some ppl seem to get really wound up when you start mentioning ttc round here, easy as winding up a bunch of nerds at a star trek convention lol.

But na man, ttc is not faster, like he said, the bottom end lag from ttc will likely increase your 1/4 mile time. It does not make any more peak power (at the same psi), but makes for less stuff to play up, makes both turbo's lifes easier (simple fact, common sense, not arguable :rolleyes: ), and because of this, allows you to run more boost safely (without worrying about the seq system fucking something up, will give you better fuel consumption, a nice fat smooth torque curve, more predictability, and imo just feels cooler :)

just how does it make the turbos life easier? I'd argue the opposite. Can't run any more boost any safer.

better fuel consumption? Did we improve efficiency somewhere? NO.

Fat smooth torque curve? You just said it will have bottom end lag... meaning lower torque at the bottom end of the RPM, rising to stock power at the top end. Thats why you feel that punch.

The only thing that you hit is that it feels different. That's because when you FINALLY get out of lag, it (only) feels like you suddenly hit boost. Similar to a single turbo which by TTC is effectively what you have made. TTC = two small turbos making one large turbo, with all it's lag......

GMACRAE, you're FOS in my opinion.
 

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98mkiv said:
just how does it make the turbos life easier? I'd argue the opposite. Can't run any more boost any safer.
98mkiv, you usually really seem to know what you are talking about, but the fact is almost everyone I hear that blows their stock turbos blows #2. Now this is most likely due to the fact that when running high boost the #2 gets slammed on in SEQ, perhaps some of the seq systems are not functing up to par, but I believe that the system just doesn't deal with 18psi well even if it's working to spec.
 

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Thanks Josh,

As you point out, it starts and stops. I wouldn't call it slamming since it is pre-spooled by the bypass valve, which is there only to gently start #2. That all it is there for.

I think there are 2 reasons for #2 failing prematurely. The first and less prevalent is that as the reed valve wears (between #1 and #2) out #1 spins #2 backwards before spinning forwards (when the bypass opens to prespool it). More likely,It is a product of simple heat soak. The forward turbo sees less heat since it is cooled (externally) by the engine fan, where the rear turbo tends to get NO airflow at all. It's not much of a difference, but it doesn't take much to make one turbo wear out 20-30K sooner than the other. Yes, the #2 fails more frequently, but I would not attribute this to the sequential system malfunctioning by poor design. Over time the reed valves get weak. I think this is much less of a contributing factor than temperature differences between #2 and #1. This is especially noticeable (the temp diff) on cars that don't idle a bit after a hard pull. The idle allows the oil to cool the housing and also the fan cools the cast iron pieces.

-M
 

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Maybe you are correct about heat/weak reel valves contributing to #2 failures. There is still the issue that at stock boost levels you are from 6-7psi on #1 alone to 11 psi, where at BPU you at at maybe 8-9 on #1 and 18-20psi, so the transistion is much sharper. Just by looking at stock dyno graphs the power curve is much flatter than at high boost BPU, where the power/boost really shoots up when #2 comes online.

I guess everything is just educated gusses at this point as to the stock turbo failues.
 
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