Just Bring It

ok, I'm thinking of going non-seq. I got 94 FD with dp, catback, intake, ecu, hi-flo and SMIC. Can someone please tell me what exactly is lag. I know it's stupid question but i don't know what exactly is. I'm sure i felt it before. I used to have a 88 Turbo 2.

Is it similart to what happens before 3500-4k in a turbo 2?

Also with my mods, till what RPM will I have lag, if i do Rikki style Non-seq, for now.

Thanks

legal-z

Lag is the period where you feel a lack of power while waiting for your boost to build. when you go non-sequential, full boost will take longer to build because both turbos are getting air all the time, thus it takes more air/a longer time to get both spinning at full boost. with your mods you probably won't have full power/boost until somewhere over 3500 rpms, whereas with the sequential setup you get full boost from the primary turbo earlier than that because the secondary is either not getting air or only getting pre-spool air. when i went non-seq, i just ended up changing my driving habits when i want to go fast, taking into account that i have to have the revs up more than stock (above 4k) to be able to step on the pedal and have immediate full boost, which for me is about 11-12psi. hope this helps.
andy

Shinobi-X

Turbos run off of exhaust air from the engine, so in order for them to spool, and make boost, it must have enough exhaust air flowing through. When you hit the throttle, lag is the time it takes to build the boost, after aquiring enough air from the engine exhaust. That lack of instant pull when you hit it is the lag. Smaller turbos (primary), use smaller turbines, that are easier (less inertia to overcome) to spin, so they have less lag- but they may spin too quickly in the high rpms, and among other reasons, are limited in the power they can create. The larger turbo (secondary), has a larger turbine, and though it has more lag (in order to spin the heavier turbine), it has the ability to create larger power. With the non-sequential system, both turbos are set to run at the same time, so it's obvious where the lag is coming from.

I haven't done the non-seq. mod yet, so I cannot answer your second question. However, if your seq. system is working fine, and you are worried about lag, it would be best to just stay in seq. mode for now. It really depends on what you are trying to do though.

rynberg

To me, there is no point to going non-sequential unless you just cannot solve your boost issues or you are racing the car a lot and want to avoid the transition spike while cornering. Those guys running upgraded turbos at over 350 rwhp also go non-sequential because the transition can be too violent at those higher boost levels.

Shinobi-x: I just wanted to point out that the secondary turbo on the FD is the same size as the primary. They are both identical Hitachi HT-12s. The TT Cosmo in Japan used a smaller primary than the secondary.

Shinobi-X

Thanks for pointing that out.

Just Bring It

well the problem is that my Sequential system is not working properly. I'm loosing boost at around 5k, which means secondary turbo problems. I have done various things to try to fix it.

First i did vacuum hose job Result -10-8-8.
I replaced TCA and TCA solenoid, the one on the lover manifold. Result - same

Then I replaced vacuum tank because it was leaking some air - or so i thought it did. - Result still same.

I checked pressure tank, charge control acuator, everything - still same results.

I also changed all check valves and still same.
In first and second gear i get like 10-8-7
Third gear 10-8-9-8 something like that.

I honestly don't know what to do anymore. I like sequential system but can't fix the damn thing. That's my main problem to go non seq.

Thanks guys.

nmo93

you might want to check the 1" hose that goes to the crv. mine was hard and no matter how much i tightened it w/ a screw clamp i was able to twist it back and forth. i replaced that and did a vacuum hose job at the same time and it fixed my boost problem.
nick

Kahren

iTrader: (13)

if your sequential system doesnt work properly FIX IT

going non seq is not an answer

RX7SpiritR

iTrader: (1)

rynberg: Are they HT-12's or HT-21's? I've heard 21's but maybe I've heard wrong.

nmo93

rynberg was right, their ht-12's.
nick

Just Bring It

Mine is hard too, but i can tighten it easy, and it doesn twist at all. I wish i could fix sequential, but if i don't, i have no other alternative.

t-von

iTrader: (8)

Hey try this. Accelerate hard in third till past transistion. Once your boost drops to 8psi and stays there(like you say it's doing), let off the throttle for a spit sec then floor it again. I had a similar problem a few months ago. My boost was 10-7-5. Once the boost droped to 5, I let off and floored it again. For some freak reason I ended up getting full boost (and this was well past 5k rpms). I later found out that the turbo outlet coupling was loose, therefore venting boost once "both" turbos were spooling. Made since to me since both turbos flowed more volume than just one. Anyways once tightend, it fixed my problem. I would also check all of your turbo outlet piping for cracks. Once the pipes expand from all the air that flows threw them, it may cause some small cracks that will only "leak" under full boost. Oh and one last thing, oily dirt around the turbo piping is a sure sign of a boost leak.