Rb20 Lag. Is There A Fix?

[Vanilla_Rice]

Probably a question raised in here a few times but looking for a quick and possibly obvious answer...

Basically after looking over a lot of other rb20 dyno figures on the results thread it occured to me that I'm even worse off in the lag department than other rb20 owners..

Feel free to look at my dyno printout in the other thread but in a nut shell im only putting out 80wkw or so at 4000rpm then makes all its power before 6000rpm.. (this was on a hub dyno aswell so could well be lower on a roller dyno)

http://www.skylinesaustralia.com/forums/Rb...&start=225#

Its increadibly laggy with the new 3'' exhaust and previoulsy with the 2.5'' exhaust was not much different. I wanna get some power down early in the rev range nothing outragous just enough to get that turbo spooling a little quicker because 4000rpm is quite righ rpm for only 80kw.

Is messing around with engine internals my only option from here? I love the rb20's so dont wanna go out and buy an rb25 just yet..

Your thoughts anyone?

Edited January 11, 2009 by Vanilla_Rice

[Weapon]

Wow, thats a pretty bad torque spread. I am guessing you still have rev limit set to about 7-7500rpm..... if so that means you'll only be getting about 1500rpm at full power.

There might be some restriction in there if the turbo manifold isn't the best quality...

No matter what you do when you push over 200rwkw you'll always lose low end torque/power but this case seems a little much. See if you can get your tune sorted and then maybe try some cams to open it up and let it breathe a bit. if you rebuild the engine with forgies then if you leave it standard bore and stroke you won't make it more torquey/powerful, it will just make it more durable

[Vanilla_Rice]

i have scratched the issue of exhaust collection being a potential problem on our kiwi forums here:

post #41 has a pic there

http://www.skylinesdownunder.com/forums/sh...7809&page=2

then on the next page it shows possible alternatives but weather this will fix the lag issues im not sure.. your thoughts??

Car has just had a fresh hub dyno tune in conjunction with its new full three inch exhaust, also being New Zealand we can get away with straight through pipes, no cat or reso's so its loud as.

Edited January 12, 2009 by Vanilla_Rice

[ZOKU]

I had a vacum leak, boost leak and exh manifold leak when my car was laggy-er. each problem I fixed, the boost built up faster, making it much better to drive slowly around town. how much vacume are you getting on idle? my rb20 sits on 58cmhg. my car needs a retune soon I think...

[Guilt-Toy]

rb20's middle name is lag. the best fix is to get rid of the problem alltogether (the rb20) and install a RB25DET or RB30DET.

[paulr33]

diff gears

aggressive tuning

clutch dumping

anti lag system

twin scroll setup

[Roy]

Ok, dump pipe type, do you run a cat? Inlet pipe to turbo, air filter type? What ECU and who tuned it? Ignition timing correct? What size wheel are you running? RB20s are not known the for their torque below 3,500rpm but i challenge people to show me why a 250rwkw RB20 cannot go punch for punch with a 250rwkws RB25 at over a fist full of revs.

Dont crack the motor, jst check the basics

[R31Nismoid]

i challenge people to show me why a 250rwkw RB20 cannot go punch for punch with a 250rwkws RB25 at over a fist full of revs.

I do remember a day when we went to calder, i do believe the RB25 was faster MPH wise?

[Roy]

I ran 113mph with 14psi Need to go back now that i have Splitfires and Racepace tune rather then the old ICE tune which ran the 10cm housing. LOL, i only had 215rwkws back then

And, you ran quicker mph Ran quicker ET Ran quicker 60ft It sux to be me

[R31Nismoid]

And that was with 220rwkw on a t04e if i remember correctly - basically the RB25 version of lag monster for fk all power!

[EFI Performance]

ohhh we know why...........

[toffy]

diff gears

aggressive tuning

and cam gears

what controls your boost?

oh and throw away your ecu imo remapped std ecu for you , raise the rev limiter to 8500 possibly throw the turbo away (replace it with a different one)?

to be honest i don't see why everyone jumps to replace the rb20 under 250rwk , you can get 1000rpm more out of it so generally you get the same type of power band... just replace the diff gears if it needs to come on sooner

disclaimer: im tired , this post may or may not make any sense and most likely should be ignored

[Vanilla_Rice]

how much vacume are you getting on idle? my rb20 sits on 58cmhg.

Not sure, ill check next time I use it

[Vanilla_Rice]

Ok, dump pipe type, do you run a cat? Inlet pipe to turbo, air filter type? What ECU and who tuned it? Ignition timing correct? What size wheel are you running?

Dumpy is 3'' right off the turbo, not sure what you mean by 'type' but its not a branded dumpy like trust or something. No cat, its a straight through pipe to rear muffler (can get away with that in nz).

Inlet pipe to turbo is below, and its a K&N pod.

Now ECU is a Link Ver 5, yes the old type.. is probably an area that lets me down a bit although I think this is more evident higher in the rev range and not so much low down.. Was tuned by TrickyTune in NZ so i doubt your familiar with them but he tunes alot of the D1NZ cars that race over here .. I asked him for an 'agressive' tune and he spent quite a while tuning to get the most out of it, timing was tweaked aswell.. compressor wheel is a 16g.

Edited January 12, 2009 by Vanilla_Rice

[Vanilla_Rice]

what controls your boost?

oh and throw away your ecu imo remapped std ecu for you , raise the rev limiter to 8500 possibly throw the turbo away (replace it with a different one)?

Only thing that controls my boost is the spring inside the wastegate

Hearing words like revert back to stock ecu make me wanna pull my hair out, i spent so much getting that link installed all on bad advice.. but I dont really want to get into an ecu discussion so ill stop that there..

As far as throwing the turbo away, the td05 is hardly a lag monster, but considering future power goals etc something like a gt3076 turbo could well be on the cards if i wanna part with heaps of my hard earned cash.

Edited January 12, 2009 by Vanilla_Rice

[TTT]

his car is a GTS4.

so he already has the shortest gears you can get for a skyline.

but being a gts4, it also means he is carrying GTR weight (my 4 door gts4 was 1450kg), while being powered by the no torque rb20.

you say your boost is controlled by the wastegate spring.

but in the dyno thread you have results from 18 psi and 22 psi..

Perhaps you could build yourself a JAYCAR boost controller.

it has the ability to keep the wastegate completely shut till the desired psi.

that should ramp the boost up quicker.

you are getting 205rwkw using 18 psi... similar power could be had using a stock RB25 turbo (well around 190rwkw with 15psi or something.. someone on here actually made 195rwkw on 14psi.. I think it's in that dyno thread)

I'd say it would make for a shit load faster car than your car currently is.

those too lazy to click his link.. his car details are:

R32 GTS4

rb20det

stock internals

td05h turbo

tial 38mm w/g, plumb back setup

rx7 flowed and tested injectors (550cc)

bosch fuel pump

Link ver5 ecu

600x300 hybrid style intercooler

k&n filter / custom stainless intake pipe

3'' full exhaust

turbo-smart ssq bov (type 2 vee port)

Running an Older Link is the problem here, cant keep up at the end and started to detonate, this was the highest run during tuning 221wkw @ 22psi.. Car is currently running 18psi @ 205wkw

[Roy]

Do you happen to know the A/R or the size housing the TD05 s running? It could be a little large as it is making decent enough power and running decent amounts of boost so perhaps it is the physics of the exhaust houing that is makign it so laggy. You dont happen to have pictures of the turbo before it went on? Is it an internal gate rear housing that you have decided to run with an external gate?

[Vanilla_Rice]

how much vacume are you getting on idle? my rb20 sits on 58cmhg. my car needs a retune soon I think...

I started it up before, and after about a min or so in idle the gauge was reading 16 In. Hg thats the unit my gauge measures in not cmhg like you said but dont know how to convert it..

[Vanilla_Rice]

Do you happen to know the A/R or the size housing the TD05 s running? It could be a little large as it is making decent enough power and running decent amounts of boost so perhaps it is the physics of the exhaust houing that is makign it so laggy. You dont happen to have pictures of the turbo before it went on?

Sorry this is the only info i could find on the turbo,

http://www.trademe.co.nz/Trade-Me-Motors/C...n-149812251.htm

Inducer: 1.89"

Exducer: 2.68"

Compressor wheel: 16G

Turbine Wheel: TD05D

This turbo was just a cheap chinese replacement option as I couldnt afford over a grand to replace with a genuine turbo at the time.. I could take a photo of the turbo installed on the car but will have to take off the inlet hose etc, maybe someone could recognise the writing on it if I do that..

Is it an internal gate rear housing that you have decided to run with an external gate?

If I understood you correctly yes it did have an internal gate that is welded shut and uses the external wastegate instead..

Edited January 13, 2009 by Vanilla_Rice

[Vanilla_Rice]

you say your boost is controlled by the wastegate spring.

but in the dyno thread you have results from 18 psi and 22 psi..

Yeah thats because we changed the springs around when he was tuning it.

you are getting 205rwkw using 18 psi... similar power could be had using a stock RB25 turbo (well around 190rwkw with 15psi or something.. someone on here actually made 195rwkw on 14psi.. I think it's in that dyno thread)

I'd say it would make for a shit load faster car than your car currently is.

Yeah true but I'd put my money on the cheap chinese turbo + setup issues being the main culprit of such high boost for such little power.. Im quite positive a good td05 would dominate an rb25 turbo in most areas but mainly maximum hp unless of course the rb25 turbo is high flowed or something.

Edited January 13, 2009 by Vanilla_Rice