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Old 02-21-2006, 04:14 PM   #1
ataac_flat04
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Question TGV tuning

An idea maybe... Is it possible to make the TGV's follow the same opening as the throttle? I was wondering if slightly closing the TGV's during light load/cruise conditions would have any effect on fuel economy. I think they can function similar to the intake runner "throttles" on some ford DOHC dual intake runner intake manifolds. They essentially open another intake runner at certain RPM/load for increased breathing. I think the SHO engine does this. Is there any reason why we couldn't do this on our engines, but use it for torque gains or mixture velocities down low?
Right now I'm satisfied with upper RPM power with the TGV's in place (I don't see the need to remove them). I would like the ability to be able to experiment with them to see if there is any gains to be had by messing with them. Anyone have any input? -Chuck
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Old 02-21-2006, 11:24 PM   #2
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What you are thinking of is a dual intake runer set up. short tunnels for high rpm hp and long ones for low rpm torque. all the nissan vq30 and vq35 have this as well as many other suche as the last eclipse.

Tuning to stay open is the best best as they do not open all the way and is just another restriction in the airway.

Joe
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Old 02-22-2006, 01:58 PM   #3
ataac_flat04
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Yes that's what I'm thinking of. Basically our intake becomes a two runner with the TGV assembly. I realize it's best for more power to leave them open or remove them for that last little bit. What I'm proposing is being able to leave them partially closed when you don't need eleventy billion HP( making that small "torque" runner), like under cruise conditions (where many people spend a lot of driving time). I wonder what the effect of introducing "tumble" in other parts of the rev range would be, other than just at cold idle. Would there be any benefit there? Think of it in the same sense of AVCS tuning, changing cam advance/retard in different places can have a small effect on idle quality and power. I wonder if adjusting the TGV's can have an effect also. -Chuck
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Old 02-22-2006, 06:41 PM   #4
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I think you missunderstood what i said. there is a butterfly on the engines with a DUAL runner design which transfer airflow to a short or longer runner depending on rpm. However we only have ONE runner so tuning the TGVs to stay open is all you will want to do.

http://www.nissanusa.com/vehicles/ModelAttributes/0,,124716|31005|,00.html
click on "variable intake"
then click on fiew for a flash demo of the two runners in action.

Again we only have one runner per cylinder.
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Old 02-22-2006, 07:08 PM   #5
ataac_flat04
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Yes, I understand we only have one runner per cylinder. We also have a butterfly valve in each runner that directs/constricts that runner essentially the same way that multi runner manifolds do, it just does it with one runner. I'm after the same benefits that multi runner manifolds have when that butterfly valve is closed. Not really concerned with runner length at this time.

What I'm asking is....It's in there for cold start idle enhancement now, can we use it to gain low end torque or fuel mileage? Not everyone wants just high HP, some of us want strong daily drivers that perhaps sacrifice some peak numbers for area under the curve and efficiency. -Chuck
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Old 02-22-2006, 07:51 PM   #6
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simple answer is NO. better gas mileage can be had by modulating the TB better. The valve will add power ONLY if taken out.
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Old 02-23-2006, 10:43 AM   #7
ataac_flat04
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Question

I'm not trying to pick a fight here. I'm glad you chimed in scoobdude, but I'd still like to be able to experiment and confirm your standing for myself. You stated there's no gain to be had, yet offered no evidence or experience that you have tried to mess with them on a Subaru. I would like to determine if the restriction of the TGV being less than open is bad or good, not just listen to theory.

Back to my original question, more directed to the ECU tuning guys with access to the code, are the TGV tables or code able to be modified? -Chuck
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Old 02-23-2006, 11:21 AM   #8
ride5000
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i don't think that there are any torque gains to be had from keeping those valves closed any longer than they need to.

if there were, after all, don't you think it'd be programmed into the ecus already? changing a few lines of code which control a tgv is a hell of a lot easier than adding avcs!!! if there were appreciable gains it would have been done.

that's my take on it at least.
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Old 02-23-2006, 11:53 AM   #9
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under certain conditions it would be helpful to have the tgv's close slightly to increase gas velocity into the head. have you ever noticed that when you go wot in the 1k-2.5k rpm range that the turbo lags and you have no power, but if you lift just a little bit (10-20%) in that range, you spool much quicker and can feel the power difference very distinctly? that is a direct result of gas velocity through the intake tract. closing the tgv's just slightly would help when the velocity of the air in the intake is quite a bit less than optimal. just as in porting heads, a bigger hole (throttle opening) does not always mean more power. gas velocity is much more important than port volume.
that said, tuning the tgv's would be a waste of time if you had to decompile the code and then experiment with different algorithms to get it to work just right. just use your right foot.
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Old 02-23-2006, 01:19 PM   #10
ataac_flat04
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diablerouge... that was exactly my line of thought on this... gas velocity. As far as algorithims, I was going to start simple, with the TGV's following the same opening as the throttle. Or if they have a map in the ECU like fuel or timing, then it would be as simple as changing values, assuming the map has more than 1 RPM column. Also remember that they direct air to a different part of the intake port, I'm curious what effect that has as well.

ride5000... I understand what you are saying, but also just because the engineers can do something, doesn't always mean they do. Stage 1 reflash nets as much HP as adding AVCS, yet they didn't do that either . Engineers aren't the bottom line when it comes to fine tuning.

Overall, I think it should be something that's investigated, along the same lines as AVCS tuning. We have the parts installed, is there any tweaking that can be done that would extract drivability. That's what I'm trying to say. -Chuck
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