SEAT Ibiza - rwd turbo
Discussion
chuntington101 said:
Max, can the turbo support 600+bhp? I know the standard gt30rs is struggling at that level with most opting for the gt35rs for extra capacity.
Do garrett offer other turbos in the race spec?
The turbo currently fitted is my spare, a "ringer" as it's a (well used!) TR30r CHRA with ex GrpA touring car housings and compressor wheels. It's good for ~600, but with a relatively high EBP and boost threshold and low comp eff. Once the car has run for a bit longer, been mapped, and proven itself, i will be swapping on my "real" TR30r (the pukka WRC spec one) based turbo. This too has modified compressor housing and a back trimmed turbine, because the std WRC framesize is optimised for low mass flow at massive pressure ratios due to the mandated 34mm inlet restrictor. Do garrett offer other turbos in the race spec?
You might ask, "why not put on the proper turbo from the start", well as the engine hasn't been fully mapped, the possibility for a f**k up during mapping, either by a "finger fault" (mistype etc) or just pushing the envelope a bit too much is high, and a TR30r is ~£7k worth of turbo on the open market, and i'd rather not have to buy another one............
Trtj said:
Thanks for the reply to my last question! So heres another 
Could you explain how your antilag system works? It certainly doesn't sound like the boy racer botches that you see on youtube!
Thanks again
The so called "ALS" you often see on youtube etc is really just bouncing a turbo car off the rev limiter and backing off, where the unburnt fuel from the spark cut then goes bang in the exhaust. Sounds impressive, but doesn't actually increase turbo speed very much!Could you explain how your antilag system works? It certainly doesn't sound like the boy racer botches that you see on youtube!
Thanks again
On my car there are two ALS strategies implemented, and the one in the video is the "pre-boost" strategy used to increase engine mass flow and turboshaft speed prior to a launch from stationary. It works as follows:
1)Driver selects 1st gear,with clutch pressed fully down, and pulls up hydraulic handbrake lever to hold car in place without rolling
2)Driver pressed LC button - dash lamp illuminates to show system acceptance at Pre-Launch hold
3)Driver removes foot from clutch pedal (system holds clutch line pressure high to keep clutch disengaged)
4)Driver floors throttle:
a) System initially goes into a closed loop speed control mode, using electronic throttle system to lift engine speed to setpoint (selectable via wet(2k5rpm)-dry(4k5rpm) switch)
b) Once at setpoint, EMS commanded to apply ignition retard and revlimit. Crucially, the retard does most of the work of limiting net positive flywheel torque, meaning that the spark cut rev limit isn't very active. The retard (approx 45deg ATDC) means the charge is burnt mostly in the cylinder for controlled combustion, with the rev limit cut only acting occasionally to keep the engine speed constant
c) Once boost pressure is positive, the throttle system switches into "MAP HOLD" mode, where the throttle position is closed loop controlled to maintain a fixed absolute manifold pressure target. This gives a highly consistent engine massflow for good repeatability.
d) At this point (takes approx 2sec typically from throttle input) the dash lamp indicates the system has primed and is ready at Launch Hold by rapidly flashing the indicator lamp.
5) Driver drops handbrake, and a microswitch registers the "off" position, and commmands the system to vent the clutch pressure (controlled to a target pressure every 1ms to give a repeatable engagement) and commands the ems to remove the rev limit and ignition retard. The throttle position is then blended from the map hold value to the current driver demand value
6) Crucially, if the system isn't used, and the handbrake remains up/on, after 15sec, or by re pressing the LC request switch, the system reverts back to normal engine idle, and subsequently, selecting neutral gear will then release the clutch once the service brake pedal is pressed!
In that(pre-boost) mode, no external bypass air is required, because the engine massflow can be high without penalty.
The second ALS strategy is Overrun boost enhancement:
In this mode, the system cannot use a high internal engine massflow otherwise engine braking is lost, and the ALS system operates in a different (and more conventional mode). Once the system senses a trailing throttle after suitable entry conditions have been met (engine temp, eng rpm, peak load before entry etc), the bypass solenoid valve is opened (intake -> exhaust manifold cleanair bypass) the throttle system slams fully shut for 50ms to create a large positive pressure wave in the intake to help initiate bypass flow, the ems retards ignition, and overfuels. During this time, throttle position is maintained at a preset target verses engine speed (a trade off between maximum negative torque (engine braking) and sufficient mass flow to cleanly push the hot vapourised fuel into the exhaust manifold).
This is a much more aggressive strategy as a lot of the burn occurs in the exhaust manifold and is hence a lot less controlled! This strategy times out after 10sec to prevent overheating of exhaust line components.
Edited by anonymous-user on Monday 7th October 12:54
Max_Torque said:
Trtj said:
Thanks for the reply to my last question! So heres another
Could you explain how your antilag system works? It certainly doesn't sound like the boy racer botches that you see on youtube!
Thanks again
The so called "ALS" you often see on youtube etc is really just bouncing a turbo car off the rev limiter and backing off, where the unburnt fuel from the spark cut then goes bang in the exhaust. Sounds impressive, but doesn't actually increase turbo speed very much!Could you explain how your antilag system works? It certainly doesn't sound like the boy racer botches that you see on youtube!
Thanks again
On my car there are two ALS strategies implemented, and the one in the video is the "pre-boost" strategy used to increase engine mass flow and turboshaft speed prior to a launch from stationary. It works as follows:
1)Driver selects 1st gear,with clutch pressed fully down, and pulls up hydraulic handbrake lever to hold car in place without rolling
2)Driver pressed LC button - dash lamp illuminates to show system acceptance at Pre-Launch hold
3)Driver removes foot from clutch pedal (system holds clutch line pressure high to keep clutch disengaged)
4)Driver floors throttle:
a) System initially goes into a closed loop speed control mode, using electronic throttle system to lift engine speed to setpoint (selectable via wet(2k5rpm)-dry(4k5rpm) switch)
b) Once at setpoint, EMS commanded to apply ignition retard and revlimit. Crucially, the retard does most of the work of limiting net positive flywheel torque, meaning that the spark cut rev limit isn't very active. The retard (approx 45deg ATDC) means the charge is burnt mostly in the cylinder for controlled combustion, with the rev limit cut only acting occasionally to keep the engine speed constant
c) Once boost pressure is positive, the throttle system switches into "MAP HOLD" mode, where the throttle position is closed loop controlled to maintain a fixed absolute manifold pressure target. This gives a highly consistent engine massflow for good repeatability.
d) At this point (takes approx 2sec typically from throttle input) the dash lamp indicates the system has primed and is ready at Launch Hold by rapidly flashing the indicator lamp.
5) Driver drops handbrake, and a microswitch registers the "off" position, and commmands the system to vent the clutch pressure (controlled to a target pressure every 1ms to give a repeatable engagement) and commands the ems to remove the rev limit and ignition retard. The throttle position is then blended from the map hold value to the current driver demand value
6) Crucially, if the system isn't used, and the handbrake remains up/on, after 15sec, or by re pressing the LC request switch, the system reverts back to normal engine idle, and subsequently, selecting neutral gear will then release the clutch once the service brake pedal is pressed!
In that(pre-boost) mode, no external bypass air is required, because the engine massflow can be high without penalty.
The second ALS strategy is Overrun boost enhancement:
In this mode, the system cannot use a high internal engine massflow otherwise engine braking is lost, and the ALS system operates in a different (and more conventional mode). Once the system senses a trailing throttle after suitable entry conditions have been met (engine temp, eng rpm, peak load before entry etc), the bypass solenoid valve is opened (intake -> exhaust manifold cleanair bypass) the throttle system slams fully shut for 50ms to create a large positive pressure wave in the intake to help initiate bypass flow, the ems retards ignition, and overfuels. During this time, throttle position is maintained at a preset target verses engine speed (a trade off between maximum negative torque (engine braking) and sufficient mass flow to cleanly push the hot vapourised fuel into the exhaust manifold).
This is a much more aggressive strategy as a lot of the burn occurs in the exhaust manifold and is hence a lot less controlled! This strategy times out after 10sec to prevent overheating of exhaust line components.
Edited by Max_Torque on Monday 7th October 12:54
Thanks
Max_Torque said:
5) Driver drops handbrake, and a microswitch registers the "off" position, and commmands the system to vent the clutch pressure (controlled to a target pressure every 1ms to give a repeatable engagement) and commands the ems to remove the rev limit and ignition retard. The throttle position is then blended from the map hold value to the current driver demand value
How do you achieve blending of ALS throttle position (map based) vs actual TPS reading?mwstewart said:
Max_Torque said:
5) Driver drops handbrake, and a microswitch registers the "off" position, and commmands the system to vent the clutch pressure (controlled to a target pressure every 1ms to give a repeatable engagement) and commands the ems to remove the rev limit and ignition retard. The throttle position is then blended from the map hold value to the current driver demand value
How do you achieve blending of ALS throttle position (map based) vs actual TPS reading?The APPS (Accelerator Pedal Position Sensor) supplies a "driver demand" throttle request at all times, the ETC arbitrates(based on mode) between this request and other requests from transmission(external) and ALS, idle speed control strategy, MAPhold strategy (all internal). Post launch blending is scheduled based on clutch position, with the driver demand given full authority with a fully engaged clutch.
(ETA: At all times the ETC reports actual throttle plate position to the EMS which helps to keep the mapping simple. This would be critical for a system using tps as a load input, however my system uses MAP (via the multirunner MAP sensor system) as it's primary load dependency)
Edited by anonymous-user on Monday 7th October 20:24
ARCHES!
After fixing the new long travel wide track suspension in place, i was easy to see that some wider arches would be required, and that significant inner wing mods would be required to maintain clearance with large diameter wheels/tyres at low ride heights.
wide boy:
Innner rear arches cut out, and lifted, including turreting the rear for the coil over struts, clearance for the driveshafts, and mounts for trailing arms and antiroll bar system
Original steel rear wings cut and widened:
Bare kevlar outer wing in position:
Modified original metal wings to get the basic shape and clearance
The bare shell with the metal work (arches, tunnel, cage, mounts etc) all complete
Next, the bare shell was sent off for acid dipping and electroplating:
When back, the rear wings were flush riveted and bonded into position:
Then the joins were masked with careful application of filler and high build primer
Next job, send the shell off for a coat of "rally car white" paint....... ;-)
After fixing the new long travel wide track suspension in place, i was easy to see that some wider arches would be required, and that significant inner wing mods would be required to maintain clearance with large diameter wheels/tyres at low ride heights.
wide boy:
Innner rear arches cut out, and lifted, including turreting the rear for the coil over struts, clearance for the driveshafts, and mounts for trailing arms and antiroll bar system
Original steel rear wings cut and widened:
Bare kevlar outer wing in position:
Modified original metal wings to get the basic shape and clearance
The bare shell with the metal work (arches, tunnel, cage, mounts etc) all complete
Next, the bare shell was sent off for acid dipping and electroplating:
When back, the rear wings were flush riveted and bonded into position:
Then the joins were masked with careful application of filler and high build primer
Next job, send the shell off for a coat of "rally car white" paint....... ;-)
sierra1off said:
Could you please tell me what language this is so i can get it translated .
Thanks
;-)Thanks
Suggest you just watch the video i posted a few pages back!
You can see the launch mode handler working in that vid actually, with an initial rev with normal sparl timing (sounds normal) then the retard coming online, and the throttle opening, the rev limiter just trimming the ocasional spark to keep the engine speed constant, and finally turbospeed (and boost) building to target. Obviously, i that video, with the garage only 3 feet infront of the car, i terminate the system after a few secs at "launch hold" ;-)
Just to clarify, not all als and nls stuff out there is rev limit rubbish.
Its capable and will be mapped onto my stock bosch me7.5 management in my S3.
Although its still dangerous in how hot it can make things, and the pressures involved. Not that you need to worry about that, this thing is engineered to perfection.
Ive never seen anything quute so extensive. I only hope to have the determination to do a similar life long project like this one day.
Thanks for sharing
Its capable and will be mapped onto my stock bosch me7.5 management in my S3.
Although its still dangerous in how hot it can make things, and the pressures involved. Not that you need to worry about that, this thing is engineered to perfection.
Ive never seen anything quute so extensive. I only hope to have the determination to do a similar life long project like this one day.
Thanks for sharing
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