Turbo lag

[hersonevia]

Hey, I have a Ca18det with a t28 turbo. I was wondering am I suppose to have turbo lag?

[Trigger]

exactly what are you calling lag...when do you get full boost?

[hersonevia]

as i shift from second to third it takes a little time.

[iliketocrash]

yes, you'll have that. ball bearing turbos i hear have almost zero transient response time though.

[f s t caz]

my car was pretty bad w/ the GTiR t28. It would drop to and start spooling again at 5psi, maybe lower. I'm interested to see how a less restrictive manifold/downpipe/entire exhaust system will effect it. but first, i need a motor to spool it again

[iliketocrash]

it also has to do with what you're using to controll boost. especially if its a mechanical boost controller

[float_6969]

Many factors will effect lag. Just because you install a BB turbo doesn't mean lag is going to go away. First of all is how well your exhaust system flows, before AND after the turbo. Secondly is your boost controller, you'll have less lag with an electronic unit. Thirdly is your BOV. If you are venting to the atmosphere, you'll have a longer lag time as the turbo will have to repressurize the system. Recirculating that BOV will allow for quicker spool times.

[hersonevia]

I still dont have a boost cont. I still have the stock b.o.v. I have the hks hi power exhaust with greddy down pipe. I have another question, I am about to do oil change, what oil am I suppose to use? Is synthetic good?

[float_6969]

An electronic boost controller will help. The CA didn't come with a BOV. Changing the turbo outlet elbow out will help as it is very poorly designed. As for the oil, it's not nearly that easy. I could talk about oil for days, and if you really want someone who knows their stuff, talk to PalmerWMD (aka Fred). Until then, check this out. It's a great site and I really like it. http://www.chris-longhurst.com....html

[rico05]

Def. do not vent your BOV if/when you have it. I just got back from a spirited drive and it is very hard to match up the harsh clutch with the repressurization of the piping and keep it smooth. As for oil, I personally run Mobil1 15W-50 but I live in Hell (aka Texas) and it never freezes here for any amount of time at all. An EBC will help as it will keep the wastegate closed for longer, usually opening right at the set pressure point. (stock will actually begin to open earlier than necessary venting off exhaust making the turbo spin less per volume of exhaust actually expelled by your eninge)

[iliketocrash]

is there and article on this whole recircing bov decreases lag thing? i don't see how recircing prevents having to "re-pressurize" the system especially when a bov is recirced to pre-turbo.

[GotBoost4Yall]

couple things i found:

function is to provide an escape route for pressurized air trapped in the intake system when the turbocharger is spinning and the throttle place suddenly closes.

A blow off valve or shift valve is a device that allows boost pressure to be relieved from the intercooler hoses when shifting and the throttle blade is closed. This has two benefits: 1. Turbo stays spooled up, there is no compressor slow down due to "stacking". 2. Turbo lives longer due to boost not "stacking" up on the compressor blade. Stacking is when the pressure in the intercooler hose's is greater than the turbo output- that's the noise you hear when you shift with an open element air cleaner, and it's very bad for the turbocharger.

I was running an s14 t28 with the SMIC at 7psi, full 3" from DP to HKS HP catback, you can feel it wasn't being used to its full potential and I also didn't have injectors so stock boost it was. I had a spare sr t25 rebuilt and putting that back on, seals on the t28 went bye bye. As far as BOV , I have an old HKS exposed, no problems.

[iliketocrash]

stacking... that's a new one. i've always heard it referred to as compressor surge. it does sound really cool though. if you have an adjustable bov you can actually set the spring rate so you get a light compressor surge sound when shifting at relatively low boost. if done right i don't think it really effects the turbo much at all either. then again i could be wrong. either way, i'd never do it myself.

[float_6969]

It can shorten the life of the turbo charger in the long run, but not as much as people would think. Remember, Nissan didn't have any sort of recirc/bov valve for the CA from the factory. Mine was just fine and it had never had one, and I never used one while it was in the car.