turbo lag.
- Thread starter dencon
- Start date
pulsar brum
New Member
maybe it running too lean and your turbo is hesitating to come on boost early.
P
pulsarboby
Guest
i ran antilag on a motec for a while and it does work to an extent but is more trouble than its worth tbh, youll also end up wrecking turbo's very quickly.
same probs as you with lag on my black car
the rally car were building should hopefully be virtually lag free with a linear power curve similar to n/a engine but with a lot more punch throughout the rev range.
im pulling out everything ive learned over the years with this build so it will hopefully be a competetive car on track.
lag's a killer and as you know and have said will cost you valuable seconds when racing.
same probs as you with lag on my black car
the rally car were building should hopefully be virtually lag free with a linear power curve similar to n/a engine but with a lot more punch throughout the rev range.
im pulling out everything ive learned over the years with this build so it will hopefully be a competetive car on track.
lag's a killer and as you know and have said will cost you valuable seconds when racing.
Thanks Bob. As you know, my car is used for hillclimbs only with a couple of sprints. Most hills have short 80/90mph straights followed with sharp first or second gear hairpins. Retaining boost while braking really hard and selecting right gear for exiting bend is the problem. I feel I loose that little bit of time each sharp bend.
Don,t get me wrong, my car is going like a dream with 6 wins out of 7 events this year so far, but like you I am always looking for that little bit more.
cheers den.
Don,t get me wrong, my car is going like a dream with 6 wins out of 7 events this year so far, but like you I am always looking for that little bit more.
cheers den.
Trip
New Member
Hey Den,
Would you sacrifice that little top end power for a turbo with less lag. Its a fine line in choosing which turbo to go for.
As Bob said, ALS workswell up to a degree. Apart from killing the turbo very quickly, they need to be setup right and in my opinion you need much more then just an ECU to enable ALS. For starters you should need to feed the engine with air, while the throttle bodies are closed. A friend of mine tried ALS on his STI using Autronic ECU, but when in transition between ALS and putting his foot down, the car was hesistant until it picks up again. I am sure if setup right it would work out perfectly, but no one had the expertise to do it locally.
What is your turbo specs ?
Lowering the turbine A/R should in theory lessen lag but will increase back pressure. Many of us use the 5 bolt internal wastegate turbine housing which will only worsen backpressure . I am no expert in Turbo talk but i might have a solution which i would hope the turbo experts can chime in. Garrett have a T25 flanged Turbine housing with a 2.5" discharge which flows similar to a full T3. Running a lower A/R with this setup should in theory reduce back pressure (compared to the higher A/R with internal wastegate) while maintaining lag to a minimum. You would need to run an external wastegate and modify the exhaust elbow though. This setup can be mated with the well loved GT3071R 84trim turbo.
http://www.atpturbo.com/mm5/merchan...tp&Product_Code=ATP-HSG-042&Category_Code=GTH
Would you sacrifice that little top end power for a turbo with less lag. Its a fine line in choosing which turbo to go for.
As Bob said, ALS workswell up to a degree. Apart from killing the turbo very quickly, they need to be setup right and in my opinion you need much more then just an ECU to enable ALS. For starters you should need to feed the engine with air, while the throttle bodies are closed. A friend of mine tried ALS on his STI using Autronic ECU, but when in transition between ALS and putting his foot down, the car was hesistant until it picks up again. I am sure if setup right it would work out perfectly, but no one had the expertise to do it locally.
What is your turbo specs ?
Lowering the turbine A/R should in theory lessen lag but will increase back pressure. Many of us use the 5 bolt internal wastegate turbine housing which will only worsen backpressure . I am no expert in Turbo talk but i might have a solution which i would hope the turbo experts can chime in. Garrett have a T25 flanged Turbine housing with a 2.5" discharge which flows similar to a full T3. Running a lower A/R with this setup should in theory reduce back pressure (compared to the higher A/R with internal wastegate) while maintaining lag to a minimum. You would need to run an external wastegate and modify the exhaust elbow though. This setup can be mated with the well loved GT3071R 84trim turbo.
http://www.atpturbo.com/mm5/merchan...tp&Product_Code=ATP-HSG-042&Category_Code=GTH
vpulsar
Well-Known Member
I've used a motec before and it's a lovely ECU when mapped well, I didn't turn on the anti lag because as Bob said it can kill your very expensive turbo quite quickly, But you can set it up to be more gentle on the turbo I believe, What I found really useful was the launch control system which was fantastic for getting away very quickly off the line, Which would come in very handy for a hill climb start I'd of thought.
But a fully fitted and mapped Motec is going to set you back the best part £2000-£2500 I'd of thought, Probably a bit much to spend on a car that struggles to be worth that these days.
John
But a fully fitted and mapped Motec is going to set you back the best part £2000-£2500 I'd of thought, Probably a bit much to spend on a car that struggles to be worth that these days.
John
Empty Pockets
New Member
Ecu's not the problem, finding a valve thats big enough to support proper anti-lag is where the problem lays, wrc one's are something like 54mm iirc, try finding one of them.
Makaveli_se7en
Member
Propper anti-lag set ups are a small fortune, other than the ecu you will ideally need to look at maram shaft turbos, some super trick exhaust valves, as Russ has said a big enough ALS valve and then you really want an inconel exhaust manifold.
Just drop a gear more?
On a first gear hairpin :shock: I suppose there's always reverse :lol:
If it was being used constantly then i'd agree but as its for sprint & hillclimb use (most runs are probably around 1 min) i think you'd get away with it as heat build up might not be as much of an issue in such a short space of time!
I reckon a decent ecu like motec or autronic set up with mild antilag (say 10 psi) would do the job without putting too much stress on the engine/turbo.
skiddusmarkus
Active Member
If its just for sprints a nice chargecooler setup would help with lag as you can lose literally metres from the piperun with one.
takumigtir
New Member
So bob what have you got planned for the engine in your rally car anything interesting? did you sort your black car out after silverstone?
P
pulsarboby
Guest
yeah turned out it was the dipstick tube that was fitted somehow got loose and popped out the block:roll::lol: this sprayed oil up onto the manifold which led to the smokescreen behind it so was a simple fix
with regard to lag issues on the rally car....well in a nutshell im gonna
1)raise the compression slightly
2)fit vernier pulleys so i can play with cam timing
3) smaller tubby....disco potato
3) 3'' elbow and system all way through
4) smooth off combustion chambers in head and fit appropiate h/g to minimise any det
5)slightly open up water jacket and match block to head to aid cooling and try keep charge temps down
6) go back to tmic but modified arc setup which will be shielded from heatsoak by having an aspestoslux slate bolted to underside which should deflect heat away from rising into cooler
7) run methanol mix to aquamist bar directly above arc and link to brake pedal switch
in theory you need charge temps at minimum on apex of bend when coming back on the power, so if the aquamist bar is linked to brake pedal (which you would be using in order to brake for the bend) then by the time you hit the apex this should give the methanol mix time to freeze and bring temps right down
car will be running around 360bhp but hopefully should get through the revs very quickly if all goes to plan
Pah! Just stamp on the clutch if its that bad! :lol:
I
iomegalinux
Guest
maybe use an water/air cooler instead of an intercooler air/air ? could help a little bit, shorter pipe to fill pressure with.
vpulsar
Well-Known Member
skiddusmarkus
Active Member
Thats the chargecooler setup I was thinking of too, on Rob's old car.If you used the disco turbo you might be able to rotate the compressor and shift a few things out the way for an extremely short piperun
I am not sure about having the aquamist spraybar on a topmount.I tried a homemade version and it can fill the plugwells with water.Even if you seal them off it could still end up settling on something electrical.
Also, when you are braking are you lifting off the throttle?If you are, then it might give the mist time to puddle on the pipework as it won't immediately mix with the air.Most systems activate off boost pressure so mixing isn't a problem as the air is there already.I am no expert on WI but I am having it fitted myself and have done a fair bit of research the past few weeks.I have settled on keeping my ERL 2c kit(needs a programmable ecu) and upgrading it to a 2d with a pressure switch and an FIA2 controller which activates at a set pressure and takes a reading from the injectors and increases water injection accordingly.
Edited to add the above is assuming you are also injecting water into the charge.
I am not sure about having the aquamist spraybar on a topmount.I tried a homemade version and it can fill the plugwells with water.Even if you seal them off it could still end up settling on something electrical.
Also, when you are braking are you lifting off the throttle?If you are, then it might give the mist time to puddle on the pipework as it won't immediately mix with the air.Most systems activate off boost pressure so mixing isn't a problem as the air is there already.I am no expert on WI but I am having it fitted myself and have done a fair bit of research the past few weeks.I have settled on keeping my ERL 2c kit(needs a programmable ecu) and upgrading it to a 2d with a pressure switch and an FIA2 controller which activates at a set pressure and takes a reading from the injectors and increases water injection accordingly.
Edited to add the above is assuming you are also injecting water into the charge.
Trip
New Member
I have looked into the water/air system for my setup but when you add the weight of the extra radiator, coolant in the system, and water pump you will be adding a minimum of 15Kg to the already heavy front of the car.
I tried the ARC topmount but for the races i race in and being in this hot country, i don't think it good. I stay at least 5 minutes idling (with ambient temp at 25deg+) at the starting line staging for my turn, and off I go for a 40 to 70sec run. I think the race is too short to cool back down the topmount. I now went for a N/D front mount.
Apart from the TMIC being exposed to heat, the engine being so close to it will also limits (to a degree) a proper flow of fresh air which can pass through its fins. Look at the boonet vents on an EVO for example, they create a sort a vacuum to suck out air aiding the flow coming in from the front. In fluid dynamics we learn that flow is governed by pressure difference (and restrictions) between both sides of the flow.
If it is possible to cool the TMIC by using other methods (as Bob suggested) It would be in my opinion a great setup.
I tried the ARC topmount but for the races i race in and being in this hot country, i don't think it good. I stay at least 5 minutes idling (with ambient temp at 25deg+) at the starting line staging for my turn, and off I go for a 40 to 70sec run. I think the race is too short to cool back down the topmount. I now went for a N/D front mount.
Apart from the TMIC being exposed to heat, the engine being so close to it will also limits (to a degree) a proper flow of fresh air which can pass through its fins. Look at the boonet vents on an EVO for example, they create a sort a vacuum to suck out air aiding the flow coming in from the front. In fluid dynamics we learn that flow is governed by pressure difference (and restrictions) between both sides of the flow.
If it is possible to cool the TMIC by using other methods (as Bob suggested) It would be in my opinion a great setup.