A.W.O.L

I was just curious if you guys would think the sequential setup would do better or worse for some highway pulls (40 mph in 2nd).

Would the sequential setup eliminate the need for brake boosting?

Thanks

TheAndyManCan

Basically,
Sequential = Faster spool, Less top end
Non-Sequential = Slower spool, More top end

I would have to say Non-Sequential would be better for highway racing.
As for brake boosting, IMO brake boosting is not neccesary in either setup, unless you don't know what downshifting is.

rynberg

They are equal on top end....UNLESS it is a FULL non-sequential conversion on a heavily modded car. Even then, it's not a huge difference....

rx7n3wb

non-sequential is mainly for simplication right?

MakoRacing

iTrader: (12)

Yup

iceman4357

iTrader: (2)

with non sqe, you get a little more lage but the power is much linear, and you dont have the turbos switching over at 4500 rpm.

1QWIK7

iTrader: (33)

if sequential wasnt a pita, i would convert back..

i guess you have to sacrifice low end power to save you headaches

1wide7

iTrader: (1)

seq is better, the main reason people switch is because something usually goes wrong and non seq is a cheap fix and it eliminates a lot,

fastcarfreak

and because its much better for drag racing. You get more mid range power.

racer1

I just switched to non-sequential and really love it. I have power above 4k when i want to step on it, and a normal car under 4k for my daily driving around the city. Also the power is more linear and a difference i noticed is that they pull strong till redline unlike before. I would recommend it for highway and drag racing. If you autox or drift then stay away.

MR_Rick

iTrader: (7)

there is not much difference on it. I'm full non-seq. The only difference is that I have better mid rage and save a little bit of more gas. I do miss my seq system some times though.

A.W.O.L

ok, thanks for the replies

rynberg

The only place that non-sequential makes more power than sequential is from 3500-4000 to 4500 rpm. That's it. A 500-1000 rpm wide band, that you would never be in for drag racing.

You are giving up 1000-1500 rpm of power on the low end for more power over a 500-1000 rpm chunk in the midrange.

Non-sequentials advantages are more reliable boost and smoother torque curve. Sequential advantage is a 1000-1500 rpm wider powerband, all at the low end for responsive street driving. Once in a track situation, the sequential setup acts like a non-sequential setup, so the only thing a non-sequential setup really gives you is simplicity/more reliable boost.

djseven

iTrader: (56)

How come all the fastest drag times are all ran non-seq??? How come you commonly see 360+rwhp with non-seq but only a few times with seq??? I dont understand where you are basing this decision. I have owned a good number of seq and non-seq cars. While the seq setup is a little more fun to drive it doesnt pull as hard up top. I can notice a difference in cars with equal mods. Just wondering where you gather your info. Im guessin it is from dyno #s by what you have stated but can you show me seq setups that make more power than a non-seq car with same mods. My studies show the opposite of what you are saying when it comes to top end power

djseven

iTrader: (56)

Just wanted to add another advantage of a seq setup......it is not near as loud as a non-seq setup

poss

iTrader: (5)

A full NS conversion gains hp from about 4000 rpm on up.

rynberg

Because:

1) Running high boost on the stock twins in seq = blown twins because of the pre-spooling of the secondary.

2) Running high boost on the stock twins in seq = violent transition.

3) Running high boost on the stock twins in seq = more likelihood of problems with the control system.

Um, maybe the fact that the turbos operate IDENTICALLY above 4500 rpm, whether it's non-seq or seq?

I NEVER said that a seq car will make more power up top than a non-seq car with same mods, but you want to compare dyno sheets below 3500 rpm?

Someone show me a dyno sheet comparision of the exact same car, with the only change being to full non-seq, that makes more than a few more rwhp up top and I will gladly accept that I am wrong. The full conversion cleans things up a little bit and allows for a little more and smoother airflow. This is not some 20 rwhp mod -- unless someone proves me wrong.....Any takers?

RTS3GEN

I'll chime in that I have converted over to nonseq and I like it and I dislike it. My seq. setup was running fine, but my turbos were old so I bought an almost brand new set and decided to go non seq to see if I liked it. I did the poor man's way first and drove the car at a PCA HPDE, which sold me on nonseq for the road course! There are several corners where you come in very hot but some where you need mid gear as a lower gear would be way too high in the rpm's and the next gear(ie 3rd) will start out lower and the turn goes into a sweeping turn onto a short straightaway. Since you can't(or I should say "shouldn't" ) shift mid turn the 3rd gear run thru said corner(s) seq. would land me right at 3300 rpm where there is a slight flat spot in power before the dip at switchover, in this case you lose a little momentum onto the coming straight. But nonseq the turbos may only be making 7 or 8 psi on their way up to 11psi, there is no loss of momentum thru the transition phase. I've taken almost a full second and a half off my lap times by going nonseq. I haven't dragged the car yet with nonseq. but it does feel faster off the line since the turbos aren't trying to transition in first gear I get full boost where I would only manage about 7psi in first gear off a hard launch before. Just my 2 cents.
Art

RTS3GEN

rynberg,
Not to say I'm a taker, but I am going to dyno the car soon with my full nonseq. setup. The mods are identical as before but I'm doing it more for comparison sake than anything else. This too, will be somewhat subjective as the turbos are almost brand new(less than 5K miles) so there may be some discrepency in this case. I will keep you posted of the results as I too am curious to see what the actual differences are on the same modification base.
ARt

rynberg

I'm confused by this, because once you cross transition, the turbos are in non-seq mode until you drop back below 3k rpm (default PFC setting). I track the car regularly and am in non-seq mode the entire time on the track -- even downshifts/upshifts do not kick it out of non-seq. (Ok, I take it back -- out of the 2nd gear hairpin at Buttonwillow, it does tend to drop back out of non-seq in that one turn...)

This also confuses me as I'm able to hit 10+ psi in first on a semi-good launch? I do suck at drag racing and my car (wasn't) modded as heavily as yours, so maybe that's part of it?

Cool, can't wait to see the results. Good luck on the dyno.

I hope to get my car back next week with BNR Stage 3s running sequentially on a mild streetported motor -- car will still have a hi-flow cat. I hope to get the car tuned in September after break-in and we'll see what she'll do....

poss

iTrader: (5)

Last I knew, Art was running a Pettit ECU. Of course, also last I knew he was a die hard sequential proponent.

I'm not sure why, but I have the same "problem" as Art. I think it just revs so fast, that the second turbo doesn't have time to fully spool up.

I should also note that I am still sequential, but have installed a nonsequential switch. I love it, it's like the best of both worlds at your finger tips. (between sequential and equivalent to a poor man's NS)

djseven

iTrader: (56)

None of this answers why the drag racers choose the non-seq over the seq? Im guessing the guys running 16+lbs repeatedly at the dragstrip really arent depending on the turbos lasting long. These guys are going for the fastest time not worrying how long the turbos will last. With a good set of used turbos going between 3-400 bucks these days and an entire turbo swap consisting of about 4-5 hrs max I dont really see the concern of longevity for the drag racers.

I am yet to take the exact same car to the dyno in both seq and full non-seq setup but it is something I may do just to see if I am right. I am in and out of a lot of these cars and the butt dyno always says the non-seq cars pulls harder. Maybe because you reach full boost on both turbos about 12-1400 rpms sooner Hands down the sequential setup is more fun to drive but I tend to go in the path of least resistance and just follow in the footsteps of the fastest guys out there. I find it hard to believe the seq setup makes as much power up top but until we have hard numbers to prove it I guess we wont know.

Who said anything about the non-seq making more power down low than seq???? You said that non-seq made no more power up top and I asked for proof. Neither of us have it at this time so I guess we wont know. I just know there are a lot more high power non-seq setups running around then sequential. This is just my take on things but feel free to prove otherwise

rynberg

How doesn't it? Drag racers are serious about setting the best times....they need an easy to maintain/consistent setup, which the non-seq gives them. It also does give a few more hp up top for the full conversion (like I said before, a few, I just don't see how it can be more than that, given the process). For all I know, the non-seq results in a more consistent/easier launch as well. Any serious drag racer is launching at 6k+ rpm with slicks, which pretty much makes the seq vs non-seq issue moot....

Even drag racers don't like breaking things unnecessarily....and running STOCK twins seq at high boost wears very hard on the secondary.

fastcarfreak

First of all it is better for drag racing, because unless you are running slicks on your stock turbo car (most people use street tires when they arent making huge power, unless of course they are very serious racers), most people drag racing are going to be in need of that mid range power.

Second of all i said it makes more mid range power, nowhere did i say that it makes more top end.

AznPhoenix

i must agree. I went from a sequential set up w/ far more mods running 13 psi to true non sesquential turbos w/ js a dp running 7 psi(due to lack of boost pill), and i can tell you this, when i ran my old fd @ 7 lbs (lack of boost pill) my new non seq fd felt js as fast or faster.