Putting a Band-Aid the lack of Torque?
02-11-11, 10:53 AM
#1
Putting a Band-Aid the lack of Torque?
Dear Experts,
Imagine a 6 port 13b, a 1.15 A/R exhaust housing and how cruddy low end acceleration is. To be honest it is nearly unsurvivable around town. I am trying to figure out what some of the options are to fix the issue and could really use some help.
First idea would be to use the best possible factory drive train options. What combination of transmission and rear end would be best. Something like S5 transmission and the 4.33 rear?
Another option is a smaller exhaust housing but I really like the security the extra flow gives me when it comes to expelling heat from the engine.
The last thing is the car has megasquirt v2. The off the stoplight tuning may be off. If i recall correctly the afrs are around 14+/-1. Spark is off from Aaron Cakes website.
Thanks for any help guys,
Chris
Imagine a 6 port 13b, a 1.15 A/R exhaust housing and how cruddy low end acceleration is. To be honest it is nearly unsurvivable around town. I am trying to figure out what some of the options are to fix the issue and could really use some help.
First idea would be to use the best possible factory drive train options. What combination of transmission and rear end would be best. Something like S5 transmission and the 4.33 rear?
Another option is a smaller exhaust housing but I really like the security the extra flow gives me when it comes to expelling heat from the engine.
The last thing is the car has megasquirt v2. The off the stoplight tuning may be off. If i recall correctly the afrs are around 14+/-1. Spark is off from Aaron Cakes website.
Thanks for any help guys,
Chris
02-11-11, 11:43 AM
#3
big port + big turbo=
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Are your six ports functioning correctly?
What are the specs on the motor? How much power are you trying to make?
I would check out what your tune looks like down low, and make sure the 6-ports are fully functional. Then look at downsizing the turbo or going to a lower (numerically higher) r/p ratio.
What are the specs on the motor? How much power are you trying to make?
I would check out what your tune looks like down low, and make sure the 6-ports are fully functional. Then look at downsizing the turbo or going to a lower (numerically higher) r/p ratio.
02-11-11, 01:53 PM
#5
and be sure you have the stock flywheel. only things to do to get better low end mainly in rotary applications is higher compression rotors, stock flywheel and/or possibly going to a supercharger. the turbine will only make up so much before it works against you a ton up top.
02-11-11, 02:32 PM
#6
The actuators are removed, the mounting points for them were removed and closed up.
We are running S4 N/A rotors on stock ports, the manifold pressure sticks to 10PSI at 4500rpm.
Downsizing the turbo is the last option because I am talking in the 1500-2500 rpm range. I am not looking for any major power difference just a little extra in being able to leave stop lights and stop signs. We are running the factory flywheel.
Would a change in gearing not help me in this department? I was thinking that and some lightening of the chassis would be enough.
Anyone run a 4.33 that can tell me the difference in the drive?
We are running S4 N/A rotors on stock ports, the manifold pressure sticks to 10PSI at 4500rpm.
Downsizing the turbo is the last option because I am talking in the 1500-2500 rpm range. I am not looking for any major power difference just a little extra in being able to leave stop lights and stop signs. We are running the factory flywheel.
Would a change in gearing not help me in this department? I was thinking that and some lightening of the chassis would be enough.
Anyone run a 4.33 that can tell me the difference in the drive?
02-11-11, 02:56 PM
#7
big port + big turbo=
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That's a really big turbo for an essentially stock 6-port at 10 psi... You could get a much wider power band throughout the rpm range, with out loosing peak power, if you went with a smaller turbo.
If you could get the 6-ports functional again, maybe electrically actuated, you would find some low rpm torque.
If you could get the 6-ports functional again, maybe electrically actuated, you would find some low rpm torque.
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02-11-11, 03:11 PM
#8
Well, we Definitely want to put the stock block to its limits this year, 10PSI is just a base line. I do not think any turbocharger is going to address the 1500-2500 RPM range power issue I am having. I was hoping for answers other then the turbocharger because of the modifications it is going to take to mount the down pipe to it. We had all the welding done by a profession with a tig and the fitment does not allow for more then .5" of movement in any direction, maybe less.
02-11-11, 07:41 PM
#10
yessir
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which intake manifolds? If you lock open the VDI chamber on the S5 non turbo intake manifolds, you really lose alot of torque in that range or RPMS. (*** dyno(by feel)) Regardless of 6 ports open or closed.
02-11-11, 08:03 PM
#11
talking head
you can mod the TB so the delay for the secondaries holds out longer
with the simple mech link ones, you tighten the dash pot on the delay
with early ones with the thermo switch and pneumatic valve to hold off secondaries while warming up
you can re-route the pneumatic signal to come from the primary runner,, engine side
vacuum on this side will hold secondary delay throttles shut
they will open to same throttle setting as the primary when the primary porting becomes restrictive an 0 vacuum or load begins to build in the primary inlet
you may need to add a little pill and make a little pinhole in the vacuum line to the valve to prevent the engine continuing to accelerate by itself in high gears when you lift throttle
( as it can create a surge of pressure into the partly open primary throttle and give an almost cruise control effect ,, it will break the signal if you also clutch in and remove load from the engine )
to do this method you must have the right TB,, and i am unsure if this same early arrangement is avail on the NA TB
with the simple mech link ones, you tighten the dash pot on the delay
with early ones with the thermo switch and pneumatic valve to hold off secondaries while warming up
you can re-route the pneumatic signal to come from the primary runner,, engine side
vacuum on this side will hold secondary delay throttles shut
they will open to same throttle setting as the primary when the primary porting becomes restrictive an 0 vacuum or load begins to build in the primary inlet
you may need to add a little pill and make a little pinhole in the vacuum line to the valve to prevent the engine continuing to accelerate by itself in high gears when you lift throttle
( as it can create a surge of pressure into the partly open primary throttle and give an almost cruise control effect ,, it will break the signal if you also clutch in and remove load from the engine )
to do this method you must have the right TB,, and i am unsure if this same early arrangement is avail on the NA TB
02-11-11, 08:10 PM
#12
^ I am going to get a throttle body with that stuff still in place and see what I can do with it. The throttle body on the car has the forward plates removed.
Thanks for something besides "modify the turbocharger"
I feel like the combination of that and a rear gear might be enough to make it drive better.
-First gen man
It is S4, thanks for the input though.
Thanks for something besides "modify the turbocharger"
I feel like the combination of that and a rear gear might be enough to make it drive better.
-First gen man
It is S4, thanks for the input though.
02-11-11, 08:20 PM
#13
talking head
^ I am going to get a throttle body with that stuff still in place and see what I can do with it. The throttle body on the car has the forward plates removed.
Thanks for something besides "modify the turbocharger"
I feel like the combination of that and a rear gear might be enough to make it drive better.
-First gen man
It is S4, thanks for the input though.
Thanks for something besides "modify the turbocharger"
I feel like the combination of that and a rear gear might be enough to make it drive better.
-First gen man
It is S4, thanks for the input though.
[ mild port turbo center plate and rotors and oil pump ]
with LPG mixer fueling and a 3.9 diff and a V trim s5 highflow ( in a s4 )
[ hell i need this trick more than you ! ]
and i have been doing this TB trick since the last century to boost engine TQ below 2500 rpm
would still love that 4.3 when i find one !
02-12-11, 01:07 AM
#14
How much power are you trying to make up top?
I know you aren't getting the answers you wanted, but this turbo seems to be improperly sized, and there's not much u can do about that other than fixing the problem. You mention swapping a trans AND diff to compensate; how is this less difficult than replacing the current turbo with one that meets your needs?
However, u did say "bandaid" right in the thread title which implies a less than optimal (hopefully temporary) solution, so I'll play along... Can u provide more details on the tune? 14's seems about right for that rpm range, perhaps it would respond better if leaner, or timing was adjusted. I doubt a TB mod is going to give u what youre looking for, its the motor that lacks response, not the throttle. I believe someone already mentioned getting the aux ports functioning properly, that would bfe your best bet. N/A rotaries are notoriously anemic w/o them and a turbo 6-port w/huge turbo will fair little better.
I know you aren't getting the answers you wanted, but this turbo seems to be improperly sized, and there's not much u can do about that other than fixing the problem. You mention swapping a trans AND diff to compensate; how is this less difficult than replacing the current turbo with one that meets your needs?
However, u did say "bandaid" right in the thread title which implies a less than optimal (hopefully temporary) solution, so I'll play along... Can u provide more details on the tune? 14's seems about right for that rpm range, perhaps it would respond better if leaner, or timing was adjusted. I doubt a TB mod is going to give u what youre looking for, its the motor that lacks response, not the throttle. I believe someone already mentioned getting the aux ports functioning properly, that would bfe your best bet. N/A rotaries are notoriously anemic w/o them and a turbo 6-port w/huge turbo will fair little better.
02-12-11, 03:10 AM
#15
talking head
those who drive a nikki with mech secondaries will relate the flat spot that comes with too much throttle too soon
this TB mod is effectively restoring the engine to two stage throttle ,, load depending
with the large secondary and aux ports combined denied from the airspeed equation until the turbo comes through
this is to maximise the airspeeds and keep the engine on the smallest port possible until required
- the same strategy that mazda use on the aux port switching in the original setup
mazda use a three stage strategy,, though without much delay between primary and secondary
this new TB setup amounts to two,, and only when the engine becomes boost assisted
when done correctly ( ie being sure the car isnt driving itself past 200 km/h in fifth with the new super cruise function )
it brings a surprising result
as is i have this magic 1.0 divided rear turbo and reasonable 0.60 front on a near identical setup and yet i still require the throttle trick,, and desire the 4.3
this TB mod is effectively restoring the engine to two stage throttle ,, load depending
with the large secondary and aux ports combined denied from the airspeed equation until the turbo comes through
this is to maximise the airspeeds and keep the engine on the smallest port possible until required
- the same strategy that mazda use on the aux port switching in the original setup
mazda use a three stage strategy,, though without much delay between primary and secondary
this new TB setup amounts to two,, and only when the engine becomes boost assisted
when done correctly ( ie being sure the car isnt driving itself past 200 km/h in fifth with the new super cruise function )
it brings a surprising result
as is i have this magic 1.0 divided rear turbo and reasonable 0.60 front on a near identical setup and yet i still require the throttle trick,, and desire the 4.3
02-12-11, 11:32 AM
#17
-sharingan 19
Thanks for the thoughtful response. When I designed the exhaust system I designed it for that turbochargers dimensions. For a V-band to properly seal it needs to be lined up fairly precisely, just like any flange. I had to have the welding done by a professional so I was not able to just tack weld as I cut pieces. So fabrication vs replacement, replacement will be more convenient.
As for power goals, at most we are looking for 400. I mentioned that a big plus to having this turbocharger is that it allows the engine to expel heat and makes for a more reliable setup, from my experience.
-bumpstart
I understand it is more then just a throttle body mod and it is the first thing I am going to do when the weather breaks. It makes sense that it may not drastically improve my the problem. A few small changes and some light weight reduction could improve it.
I am considering a smaller turbocharger but nothing I put on will be small enough to address the rpm range I am talking about.
Thanks for the thoughtful response. When I designed the exhaust system I designed it for that turbochargers dimensions. For a V-band to properly seal it needs to be lined up fairly precisely, just like any flange. I had to have the welding done by a professional so I was not able to just tack weld as I cut pieces. So fabrication vs replacement, replacement will be more convenient.
As for power goals, at most we are looking for 400. I mentioned that a big plus to having this turbocharger is that it allows the engine to expel heat and makes for a more reliable setup, from my experience.
-bumpstart
I understand it is more then just a throttle body mod and it is the first thing I am going to do when the weather breaks. It makes sense that it may not drastically improve my the problem. A few small changes and some light weight reduction could improve it.
I am considering a smaller turbocharger but nothing I put on will be small enough to address the rpm range I am talking about.
02-12-11, 09:25 PM
#18
well i did mention the stock FD twins but you would have to have an engine management system that could control the sequential system but that WOULD get you near your goal HP range and still actually give some response below 2500RPMs. it also wouldn't work with most FC intake manifolds without some ingenuity.
02-13-11, 03:13 AM
#19
Rotary Freak
you can mod the TB so the delay for the secondaries holds out longer
with the simple mech link ones, you tighten the dash pot on the delay
with early ones with the thermo switch and pneumatic valve to hold off secondaries while warming up
you can re-route the pneumatic signal to come from the primary runner,, engine side
vacuum on this side will hold secondary delay throttles shut
they will open to same throttle setting as the primary when the primary porting becomes restrictive an 0 vacuum or load begins to build in the primary inlet
you may need to add a little pill and make a little pinhole in the vacuum line to the valve to prevent the engine continuing to accelerate by itself in high gears when you lift throttle
( as it can create a surge of pressure into the partly open primary throttle and give an almost cruise control effect ,, it will break the signal if you also clutch in and remove load from the engine )
to do this method you must have the right TB,, and i am unsure if this same early arrangement is avail on the NA TB
with the simple mech link ones, you tighten the dash pot on the delay
with early ones with the thermo switch and pneumatic valve to hold off secondaries while warming up
you can re-route the pneumatic signal to come from the primary runner,, engine side
vacuum on this side will hold secondary delay throttles shut
they will open to same throttle setting as the primary when the primary porting becomes restrictive an 0 vacuum or load begins to build in the primary inlet
you may need to add a little pill and make a little pinhole in the vacuum line to the valve to prevent the engine continuing to accelerate by itself in high gears when you lift throttle
( as it can create a surge of pressure into the partly open primary throttle and give an almost cruise control effect ,, it will break the signal if you also clutch in and remove load from the engine )
to do this method you must have the right TB,, and i am unsure if this same early arrangement is avail on the NA TB
02-13-11, 12:19 PM
#21
it's only an option if the delay system hasn't been adjusted properly to begin with. usually the dashpots are out of ajustement, have lost a bit of their slowing tension and the spring on the secondary return cam is also not holding as it originally was designed to. most of the time i see the plastic cam rub stoppers are cracked and/or missing too which really affects it a bit.
the system works but usually it is working either far too slowly(dried out components sticking) or far too quickly(broken cams or weak dashpots) for one of the reasons mentioned. some people see benefits in low end holding the secondaries closed until upper RPMs more than others, it really depends on the tune and how the car is setup.
the system works but usually it is working either far too slowly(dried out components sticking) or far too quickly(broken cams or weak dashpots) for one of the reasons mentioned. some people see benefits in low end holding the secondaries closed until upper RPMs more than others, it really depends on the tune and how the car is setup.
Last edited by RotaryEvolution; 02-13-11 at 12:21 PM.
02-13-11, 02:47 PM
#22
Rotary Freak
I could buy a simple voltage switch from JayCar and set it to trip the solenoid off the boost/pressure sensors signal to the ECU. No worry 'bout putting a pin hole in a vac line etc. and no worry 'bout an unauthorized cruise control like he mentioned. Cost? Thirty bucks I figure if using a spare stk *emissions* solenoid.
02-13-11, 09:13 PM
#23
talking head
I could buy a simple voltage switch from JayCar and set it to trip the solenoid off the boost/pressure sensors signal to the ECU. No worry 'bout putting a pin hole in a vac line etc. and no worry 'bout an unauthorized cruise control like he mentioned. Cost? Thirty bucks I figure if using a spare stk *emissions* solenoid.
( i have no ecu and no 5 V bus to run a map sensor, but i do like the hobs switch idea )
but for those with that option
methods using vac switch or ecu out to pull and dump the vacuum with a redundant birds nest solenoid are practical solutions to the inadvertent super-cruise
again i will remind those who experience it,, that a clutch dip will stop the issue when it goes scary
and its a unique experience to have your rotary engine vehicle TQ away in 5th or 4th with only light or no throttle applied
this setup may surprise a few- when they get the balance right-
here is a pic of stuff from the pit
- early style s4t TB with the single throttle secondary delay vac can and no mech dashpot
( right,,underside showing,,, can visible )
02-13-11, 10:08 PM
#24
yessir
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I can sorta vouch for bumpstart.
I experience (*** dyno) a decent drop in power if I go over half throttle before 4~5 grand. Or quarter throttle before ~3 grand. (s4 non turbo w/ only ported manifolds and ported/stripped throttle body.)
I have been wanting to put the vacuum operated secondary throttle plates back on to see how much they help or not. It seems like it would be nice to be able to WOT ONLY the primary plate until a certain RPM. Which I believe is the reason for the additional two vacuum operated butterfly's I have been religiously removing... I'm not 100% sure that they are there for that reason. (can someone confirm?)
The rx8 operates like this. With the single butterfly throttle body, the control is done with valves in the manifold. You can WOT and only the primary runners are open.
I experience (*** dyno) a decent drop in power if I go over half throttle before 4~5 grand. Or quarter throttle before ~3 grand. (s4 non turbo w/ only ported manifolds and ported/stripped throttle body.)
I have been wanting to put the vacuum operated secondary throttle plates back on to see how much they help or not. It seems like it would be nice to be able to WOT ONLY the primary plate until a certain RPM. Which I believe is the reason for the additional two vacuum operated butterfly's I have been religiously removing... I'm not 100% sure that they are there for that reason. (can someone confirm?)
The rx8 operates like this. With the single butterfly throttle body, the control is done with valves in the manifold. You can WOT and only the primary runners are open.
02-14-11, 08:06 AM
#25
Rotary Freak
The outer set of secodary are for cold running/choke. When the water warms up the water thermo sensor cuts the path of vacuum to the outter sets diaphram and then they open all the way for the rest of the drive.
Most people remove them for faster throttle response. I just removed the small rod/spring and tied them open and drove it like that for a while. Decided it wasn't worth removing them and reinstalled the rod/spring................the rod/spring ties the outter set to the linkage if there's doubt as to what I referr to. Talking stk turboII USA version which has the vac diaphram plus the damper and cam to slow down the opening of the inner set of secondarys. Make sense? Probably not.
EDIT: Meant to add a snide remark. I have a stk unbutchered TurboII. I also have a non turbo engine converted to Turbo in another car. That non turbo to turbo sucks big time under 2500 rpms. Makes me wonder why on gods green earth I ever did it when I've a good stk turboII engine sitting in the shed. They are NO GUTS at all under 2500 with a stk turbo. Sooooooo the idea of making the outter set of secondarys open much later has appeal to me. Like BumpStart says ...in effect......they'll act similar to the way the non turbo aux acturators worked i.e. cutting off the secondary ports til the time has arrived for them to open. Seems that way to me.
A 1960 VW has more torque than a six port conveted to turbo......below 2500 rpm.
Most people remove them for faster throttle response. I just removed the small rod/spring and tied them open and drove it like that for a while. Decided it wasn't worth removing them and reinstalled the rod/spring................the rod/spring ties the outter set to the linkage if there's doubt as to what I referr to. Talking stk turboII USA version which has the vac diaphram plus the damper and cam to slow down the opening of the inner set of secondarys. Make sense? Probably not.
EDIT: Meant to add a snide remark. I have a stk unbutchered TurboII. I also have a non turbo engine converted to Turbo in another car. That non turbo to turbo sucks big time under 2500 rpms. Makes me wonder why on gods green earth I ever did it when I've a good stk turboII engine sitting in the shed. They are NO GUTS at all under 2500 with a stk turbo. Sooooooo the idea of making the outter set of secondarys open much later has appeal to me. Like BumpStart says ...in effect......they'll act similar to the way the non turbo aux acturators worked i.e. cutting off the secondary ports til the time has arrived for them to open. Seems that way to me.
A 1960 VW has more torque than a six port conveted to turbo......below 2500 rpm.