Has anyone gone from 60 mm TB BACK to stock?

[Tony D]

Now that you mention it ray, the two-barrel Nissan EFI T/B has a similar setup, as does the Mazda one I mentioned earlier-both a kidney-beam shaped cam, and a linkage with more geometry to slow the initial opening and then accelerate opening past a point of linkage travel.

 

I just found this in one of the posts mentioned earlier in the thread:

randy 77zt

Member

Group: Members Posts: 1215 Joined: 08-August 00 Location:modesto ca Posted 2 days ago

 

on some of the newer cummins diesel engines the turbo has shaft speed sensors.i would assume this is used as an input to the engine ecm.the engine ecm would use this to compute the output for the vgt adjustor servo on the turbo.engine has no waste gate-the vgt just lets some of the exhaust gas by on the turbine side.some of the newer after markit efi systems can use turbine speed and control a vgt

 

Gee, who suggested this control scenario. Why is Cummins going away from a wastegate and using a turbine shaft speed indicator?

Edited June 10, 2010 by Tony D

[col]

The blow off I was refering to was the blow off valve in place. If that will vent enough flow I was wrong.

As I said the bleed system would be better.

The surge you seem to be talking about is there on all engines with a standard gate when you are on and off the throttleand isn't enough to break the average turbo.

There is no point to this back and forth between us, as it is not helping the thread. If you concider what I put forward as rubbish thats ok with me. I will eventually try this system and then I will leave some more usefull feedback. Sorry for giving an opinion.

[Tony D]

The blow off I was refering to was the blow off valve in place. If that will vent enough flow I was wrong.

As I said the bleed system would be better.

The surge you seem to be talking about is there on all engines with a standard gate when you are on and off the throttleand isn't enough to break the average turbo.

There is no point to this back and forth between us, as it is not helping the thread. If you concider what I put forward as rubbish thats ok with me. I will eventually try this system and then I will leave some more usefull feedback. Sorry for giving an opinion.

 

Opinions are great, even when they are wrong. They become a problem when people refuse to acknowledge any logical and informed dissent trying to show how physical devices work.

 

You will change the laws of physics, don't be upset that I presented physical facts to question your proffered idea, or to explain why an alternate approach would offer something better in terms of the original post.

 

As we are apologizing, sorry for assuming informed dissent and debate towards the end of educating someone and combating ignorance was seen as offensive or combative.

 

Remember: In the physical world, there is right and wrong. You can't break the rules. All I ever asked you for was the mechanisim by which your 'idea' would overcome the obstacles I showed you would exist. When you 'do eventually try it' by all means give feedback. But remember that as someone who has tried wastegate only systems, and found them lacking (as have many OEMS and most racing teams now...) I choose to look forward in technology (which as I said may actually be looking back 30 years to the 80's!) and that is what this site is about. Looking forward to new ways of doing things, not simply rehashing the turbogroup fueler concept without the variable fuel delivery control loop (look it up!)

[HowlerMonkey]

You might be suffereing form Diabetic Nuropathy...If you can't tell the tip-in characteristics are different from a 50 and 60mm T/B using stock linkage. There is most definately a change. It's what all the butt-dyno experts attribute as 'horsepower increase' after installing the 60mm.

 

But this is straying from the OP's issue of on-boost modulation which is a VERY sensitive subject compared to ANY N/A car. A larger T/B will make the tip-in touchy and more power will exacerbate this. If you can feel it in a stocker with 140HP, it's worse on a turbo car with 300+!

 

My experience with both the 60mm and the 50mm showed me that the biggest difference in "tip in" response is the changing from the stock progressive linkage to a linear linkage......or someone modified the stock linkage to the point that the lesser authority at the beginning of the travel has been moved or negated.

[Tony D]

My experience with both the 60mm and the 50mm showed me that the biggest difference in "tip in" response is the changing from the stock progressive linkage to a linear linkage......or someone modified the stock linkage to the point that the lesser authority at the beginning of the travel has been moved or negated.

 

If the 60mm is connected to the same linkage as the 50mm was (the vast majority of setups out there, most people seem reluctant to expend the effort to go cable or alter linkage geometry) the tip in can be attributed to delta-change for equivalent angluarity change on the throttle shaft. It's not attributable to linkage. Which was the point all along: induce non-linear actuation (through alternate geometry or cable and eccentric cam). For the same 20 degrees of throttle shaft rotation, the 60mm flows more, and makes more relative change in airflow capacity than the 50mm, that is why it 'tips in' harder.

 

I would classify the stock linkage as linear, and the cable as equally linear, but without any mechanical slop.

 

BOTH systems need alterations to induce a NON-Linear response in the first 35-50% of the throttle pedal movement.

 

Someone can verify this: Stock pedal and linkage moves (Example) 25%, Throttle Body Shaft moves X% (say 25---or equate to degrees, say 22.5 degrees rotation). At 50% you have 50% throttle (or 45 degrees Throttle Shaft Rotation).

 

What you want is to alter this so that for that same pedal travel of 25%, you get <25% Throttle Body Shaft Movement.

 

In EITHER case, 100% travel of the pedal will always equal (or should) 90 degrees of rotary motion on the Throttle Shaft.

 

It's like a valve characterization pair. Normally it's 1:1, but if you could do it electronically it would be more like Pedal Movement:Throttle Body Rotation 0%:0%, 10%:1%, 20%:5%, 30%:10%, 40%:15%, 50%:20%, 60%:25%, 75%:35%, 80%:50%, 85%:60%, 90%:75%, 95%:85%, 100%:100%

 

From a graph of those pairings you can see that the first 75% of throttle pedal travel will take you to highway speeds and cruise easily enough. Once on the freeway the pedal becomes 'on-off'...

 

Once you characterize the response you want graphically, you can calculate what you want, and equate it to linkage angles, or even a custom CNC profile for the throttle cam. The important thing is you have to figure out where 'normal driving' occurs and deaden the pedal to that point, and understand that 85% of the cars driving will be done there. After that, you are definately wanting full power and modulation becomes less of an issue.

 

If there was datalogging available in the OP's car, I'd say watch the TPS inputs in the corners where the issue occurs, and deaden the pedal past that point. If he's having modulation issuesat a TPS of below 50% (45 degrees rotation, and I'm betting it is) then deaden it to that point plus 10%, and make the throttle 'on-off' progressive past that point. In straightline or drag racing it won't make much difference. But where sensitive throttle inputs occur, this will make the car feel more 'driveable' (easier modulation)...

 

We have to do this to linear caged valves on unloading (blowoff) valves --- instead of changing their response characteristic to non-linear we electronically alter the control signal so the linear cage ACTS like a non-linear cage. The operator never knows the difference, for all intents and purposes it ACTS like a totally different valve.

 

I do this every day at work, I kinda got a handle on valve characteristics. Fixing this is a simple matter of linkage geometry once you know where you want your response characteristic to be. Electronically or mechanically, the approach is the same.

 

<EDIT> I'll add that the throttle pedal in a late 90's Suburban is much like this, you rest your foot on the pedal and you will stay at 55-65 mph. There is resistance via spring to hold you at a cam breakpoint. This breakpoint is at approximately 75% of throttle pedal travel. You think the thing is a lumbering wallowing beast because it just takes a LOT of pedal movement to get it going. But it works to save gas and makes driving the truck easier. Whoming the pedal past that point makes power come on QUICKLY. Doing a WOT (which you have to press VERY hard to achieve) results in squalling burning tires. GM toned it down so that the 90% of peopel that drive it don't come back with complaints about 'touchy throttles'. You can do the same thing, it's all geometry.

Edited June 12, 2010 by Tony D

[rayaapp2]

If the 60mm is connected to the same linkage as the 50mm was (the vast majority of setups out there, most people seem reluctant to expend the effort to go cable or alter linkage geometry) the tip in can be attributed to delta-change for equivalent angluarity change on the throttle shaft. It's not attributable to linkage. Which was the point all along: induce non-linear actuation (through alternate geometry or cable and eccentric cam). For the same 20 degrees of throttle shaft rotation, the 60mm flows more, and makes more relative change in airflow capacity than the 50mm, that is why it 'tips in' harder.

 

I would classify the stock linkage as linear, and the cable as equally linear, but without any mechanical slop.

 

BOTH systems need alterations to induce a NON-Linear response in the first 35-50% of the throttle pedal movement.

 

Someone can verify this: Stock pedal and linkage moves (Example) 25%, Throttle Body Shaft moves X% (say 25---or equate to degrees, say 22.5 degrees rotation). At 50% you have 50% throttle (or 45 degrees Throttle Shaft Rotation).

 

What you want is to alter this so that for that same pedal travel of 25%, you get <25% Throttle Body Shaft Movement.

 

In EITHER case, 100% travel of the pedal will always equal (or should) 90 degrees of rotary motion on the Throttle Shaft.

 

It's like a valve characterization pair. Normally it's 1:1, but if you could do it electronically it would be more like Pedal Movement:Throttle Body Rotation 0%:0%, 10%:1%, 20%:5%, 30%:10%, 40%:15%, 50%:20%, 60%:25%, 75%:35%, 80%:50%, 85%:60%, 90%:75%, 95%:85%, 100%:100%

 

From a graph of those pairings you can see that the first 75% of throttle pedal travel will take you to highway speeds and cruise easily enough. Once on the freeway the pedal becomes 'on-off'...

 

Once you characterize the response you want graphically, you can calculate what you want, and equate it to linkage angles, or even a custom CNC profile for the throttle cam. The important thing is you have to figure out where 'normal driving' occurs and deaden the pedal to that point, and understand that 85% of the cars driving will be done there. After that, you are definately wanting full power and modulation becomes less of an issue.

 

If there was datalogging available in the OP's car, I'd say watch the TPS inputs in the corners where the issue occurs, and deaden the pedal past that point. If he's having modulation issuesat a TPS of below 50% (45 degrees rotation, and I'm betting it is) then deaden it to that point plus 10%, and make the throttle 'on-off' progressive past that point. In straightline or drag racing it won't make much difference. But where sensitive throttle inputs occur, this will make the car feel more 'driveable' (easier modulation)...

 

We have to do this to linear caged valves on unloading (blowoff) valves --- instead of changing their response characteristic to non-linear we electronically alter the control signal so the linear cage ACTS like a non-linear cage. The operator never knows the difference, for all intents and purposes it ACTS like a totally different valve.

 

I do this every day at work, I kinda got a handle on valve characteristics. Fixing this is a simple matter of linkage geometry once you know where you want your response characteristic to be. Electronically or mechanically, the approach is the same.

 

<EDIT> I'll add that the throttle pedal in a late 90's Suburban is much like this, you rest your foot on the pedal and you will stay at 55-65 mph. There is resistance via spring to hold you at a cam breakpoint. This breakpoint is at approximately 75% of throttle pedal travel. You think the thing is a lumbering wallowing beast because it just takes a LOT of pedal movement to get it going. But it works to save gas and makes driving the truck easier. Whoming the pedal past that point makes power come on QUICKLY. Doing a WOT (which you have to press VERY hard to achieve) results in squalling burning tires. GM toned it down so that the 90% of peopel that drive it don't come back with complaints about 'touchy throttles'. You can do the same thing, it's all geometry.

 

 

I believe you've killed this one Tony. lol

 

Its funny I remember you making an extremely similar statement about the Suburban/Gm trucks years ago on Zcar.com. I wish I could find that thread, but it was back in like 2003-2004.

[Brad-ManQ45]

Since I am converting my car from a T5 to automatic, I'll leave the linkage the way it is - let the torque converter work for me!

[woldson]

Umm, what stall are you considering then...

[Brad-ManQ45]

It's gonna be a GM 4L60E and I have a converter from PTC that is around 3K based on what I gave as parameters.

 

Boost onset ~2800, full boost ~3500.

 

Torque @ 3000 ~300 lb/ft.

 

This ought to be fun - basically the same 1st gear as the T5 w/a torque converter - 2nd ought to hit HARD!

[HowlerMonkey]

Stock linkage is not linear.

 

It is impossible for it to be linear through it's near 90 degrees of throttle shaft movement.

 

On the 280zx throttle body linkage, it starts out with the minimum authority and gains authority in relation to the throttle pedal movement the further it is opened.

[Tony D]

Stock linkage is not linear.

 

It is impossible for it to be linear through it's near 90 degrees of throttle shaft movement.

 

On the 280zx throttle body linkage, it starts out with the minimum authority and gains authority in relation to the throttle pedal movement the further it is opened.

Argh, you completely missed the point!

 

OK. ASSUME the SAME linkage on both TB's. 60mm and 50mm.

 

Now, calculate throtle plate opening area.

 

NOW, from a 0% rotation to 10 Degrees rotation, calculate the RELATIVE THROTTLE OPENING CHANGE between the 50mm and 60mm T/B.

 

Because the 60mm flows an appreciable figure more (and knowing what that number is will allow you to 'pair that' with an equivalent 50mm T/B opening) you need LESS throttle angle on the 60mm body for the same 'modulation'...

 

By using that formula, you will know EXACTLY how much to alter the linkage to give similar tip-in characteristics between the two.

 

When you look at the valve flow coefficient the non-linear response to a linear rotation characterized in degrees may be plotted, and valves of different flow characteristics may be made to feel as though they are identical. This is what happens with fly-by-wire.

 

For all intents and purposes the TB opening is 'linear' as you use the 50mm as your baseline to compare with a 60. You manage the DIFFERENTIAL CHANGE to make modulation similar. And to do this you need FAR MORE non-linearity on the 60mm TB than you do on the 50 to get the same 'feathered throttle' feeling.

 

If you want to split semantic hairs fine, but you're throwing out the baby with the bathwater arguing a moot semantic point. Throttle opening is in degrees, and THAT IS LINEAR and comparable between the bodies.

 

The flow given per angle of throttle rotation is not linear, and far mor dramatic at low throttle angles on the 60 relative to the 50.

 

Don't loose sight of what is being discussed. You will miss the forest in all the trees. You've already been discounted in the discussion as not being able to 'feel' the flow difference with identical linkages (a physical law at work there, BTW) kind of means stating the obvious (not linear throough 90 degrees of motion---who said it was?) is not contributing anything to the thread.

Edited June 22, 2010 by Tony D

[HowlerMonkey]

I was wrong and I sure don't deserve the ad hominem crap spewed in earlier posts on this thread.

 

I as wrong because I forgot to figure in the other "bellcranks" in the stock linkage which change the "curve" and possibly nullify the progressive nature of the geometry concerning the bellcrank at the throttle body.

 

Sure there is an area difference between the 60mm and 50mm throttle bodies at very small openings but the difference is just not enough to cause a huge driveability issues listed by others above since those same "surging" issues exist with the stock 50mm throttle body.

 

The perception of difference between the two is usually a problem since most "upgrades" that include going from 50 to 60mm usually include much more than just the throttle body alone.

 

Compare the difference back to back on the dyno and you find very little at same measured throttle angles.

 

I will get back to this at another date and prove my points with potentiometer tps data corrected to true throttle angle data with two back to back dyno runs (dyno dynamics twin retarder) on a stock L28et with both 50 and 60 but I'm very busy changing upwards of 240 valve springs per week at lexus while finishing the current official standing mile record holding car for october's texas mile competition.

 

Come on by and see us at the Texas Mile on october 16.

Edited October 8, 2010 by HowlerMonkey

[Tony D]

Wow, Necroposting.

[HowlerMonkey]

Just busy preparing the current world record standing mile holder for the texas mile.

 

Actually.....just seeing how far getting the last word in will continue.

Edited October 17, 2010 by HowlerMonkey

[Tony D]

Well, you've said that twice now. We got it the first time. How is that relevant to the thread?

[Gollum]

Well I'm glad it was brought back up. Because I've been thinking about what you've been saying in regards to turbine speed/boost control in this thread tony and I'm still somewhat unclear on some things.

 

What were you using to control the wastegate's movement? Was it basically a map based on the max flow of the engine at full RPM? If so how is part throttle flow calculated. Seems like this would be a serious headache to figure out, or is it just some basic tuning time to figure out?

 

It makes sense that if you had a speed sensor on the turbine shaft that this is all an EASY thing to figure out. Just find the optimal RPM for the turbo and run the wastegate against that. You could even log the positioning and then make a map to follow to keep from any possible "control jitter" from happening.

 

But without any way to tell what speed the turbo is really at it seems like it would be a challenge to tune.

 

Also, how was this setup on the street? I'd image since you said it was akin to a supercharger setup, that it was quite tame if you kept your foot out of it, but had instant power with full throttle anything close to boost threshold, which was insanely low.

 

I'd love to try this out on my car, and maybe even my friend's STI, since he hasn't been so happy with how hard boost comes on with just the stock electronic wastegate control. Adding a boost LEAK with a manual controller helped, but he's obviously loosing some threshold. But it makes it much more livable on the street. It doesn't help that he's a lead foot and knows it, but I think if he had more control like you have in a supercharged setup he'd be much happier overall.

 

And he's certainly not going to be turning his boost DOWN anytime soon. He's hoping to get close to some records when it comes to using the stock turbo on a STI.

[Tony D]

If you look at the photo I posted yesterday in the S130 forum in the 'guess the cars hp' thread, it has the Z32 GTPZX dyno sheet...take a look at what the turbo boost is doing and tell me how that was achieved!

 

One of the things the original Electramotive Company still sells is a turbocharger tachometer.

 

 

Engine flow is irrelevant...the pid loop is based on turbo speed, and the actuator on the wastegate is set to track that. The BOV is set to maintain manifold pressure as you want it (see those 'steps' in the dyno sheet posted? Wonder how that was achieved on a WOT pass from 4000 to 8000? It CAN NOT happen like that from wastegate-only control. If you have the ECU controlling turbo speed and the controller for the BOV set to maintain manifold pressure based on rpm, throttle position, etc, you can actually tailor your power delivery so power comes on when you have sufficient traction, and really lay torque down.

 

I took a ride in that car that the dyno sheet is taken from down in SanDiego in 1994 at the Z-Con Auto-X. Phenomenal. Johnny O'Connel was driving in Jack Murphy Stadium Parking Lot. Got some bitchin' video on VHS someplace of some other people riding around in it as well. It was restricted at that point, though, only making 750 or so horsepower, but with A LOT more torque down low. The car (according to Steve Millen and O'Conner) was MUCH more driveable with less HP and more torque.

 

Most guys were sensory overloaded, I was. But I was spending a lot more time watching gauges trying to figure out what I was seeing. And I hadn't seen that dyno sheet until really recently. It is all making sense now what I was feeling while in the car, and how they achieved it now.

 

Plus, some other things relating to the contrasts between tuning the VG30 for 1000HP versus the L28 for the same level of power. Some of the stuff Knepp said and was proud of now starts to make a lot more sense. As we deal with JeffP's car, we are starting to get a much clearer picture of what E-Motive did, and now that my fellow engineer is here in China with me, and has FINALLY brought all the damned manuals with him for this setup, I got to take them and then read a LOT on the plane to get up to speed. JeffP may now have a totally different way to control his boost.

 

And I may have a way to run a GT35 on a non-ported head without partial throttle surge and hellacious holeshots!

 

But I digress...

[Gollum]

Well turbos don't spool like that boost plot, so the boost HAS to be controlled through a BOV control like you're talking about.

 

I'm curious to know how it's being actuated though. Because those steps in boost look like they're being electronically controlled the way they spike and then taper down. It looks the same the way an electronic boost controller usually can't quite hold boost at or bellow peak right as it opens. But the front of the ramp is completely different than an electronically controlled wastegate turbo control, especially for those power levels.

 

Thank you for the insight though Tony. You da' man.

 

It seems that controlling the turbo with a basic loop with a speed sensor is easy as cake! And upon a basic google search I found this - http://www.turbobygarrett.com/turbobygarrett/products/Accessories_continue_speed_sensor.html

 

Seems like there might be others that agree with this form of turbo control.... surprise...

 

 

A total side note, for arguments sake (which doesn't mean I disagree, just want clarification). Should we really be calling a BOV when it's being used for venting excess charge a BOV? Seesm like a Pop-off valve might be more accurate in this instance.

[Gollum]

I didn't get into this in my last post but they're also obviously not setting their boost control method, whichever it may be, to max boost as early as possible, making the torque curve more tame down low. You can see it make it's jumps which leads me to think they would otherwise have problems keeping the engine controllable if they just fed it as much boost as the turbo was making.

[mario_82_ZXT]

I know we've strayed from the original thinking of an eccentric throttle cam, but does anyone have any recommendations on how to go about designing one?

 

My dad complains about the throttle in our cable converted 60mm setup.