parallel vs. sequential
07-31-07, 06:07 AM
#3
this is like asking which oil is best for the car. There are a lot of opinions from both sides, neither setup is perfect. Both have their up sides and their downsides.Basic sticking points that I've seen are as follows:
Sequential Pros:
Quick spool
Sequential Cons:
tends to be a lot of upkeep
Second turbo "surprise"(some people like this, but it can hardly be considered a positive)
Parallel Pros:
simple; easy to trouble shoot
not much to break
marginally higher output(maybe 5hp, probably mostly due to the flow improvements)
Parallel Cons:
Does not spool up as fast(from what I hear, an open exhaust, open intake and a streetport and doing the conversion fully can greatly reduce turbo lag getting it close to the same as sequential)
FWIW, I refuse to take my FD to the city, so stop and go driving is a rarity. For me, if I have to wait an extra 300RPMs for the turbos to spool it's no big deal because I live in a very rural area. I'm having "the guys" mod it to be fully non-sequential, because it's just easier to have it that way than to worry about vacuum hoses blowing off or solenoids getting stuck.
07-31-07, 09:03 AM
#7
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i have the poormans version running 10psi. lag is more noticeable, the car does feel like a slug if youve JUST come from sequential or from a car that has a smallish turbo like my s15.
daily driving isnt a problem because even off boost the car has no problems matching it with traffic. My friends also know when i hit boost cos the race will start even and then ill just rocket away.
daily driving isnt a problem because even off boost the car has no problems matching it with traffic. My friends also know when i hit boost cos the race will start even and then ill just rocket away.
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Gear2078 (03-31-22)
07-31-07, 11:26 AM
#10
2/4 wheel cornering fiend
What "upkeep"? I did a silicone hose replacement almost 10 years ago, and haven't touched the sequential system since.
My transition is practically smooth as silk, even at 13 psi. Hardly could be considered a surprise, especially since I've lived with it for over 10 years.
FWIW, I drive in both urban and rural areas (plus racetrack when I can find the time, which has unfortunately been scarce), and I love having near-instant response rather than having to deal with all the additional modifications and hassles associated with running a full exhaust just so that the turbo lag can be reduced to bearable levels. If I want to deal with lag, I'd just go with a single turbo.
FWIW, I drive in both urban and rural areas (plus racetrack when I can find the time, which has unfortunately been scarce), and I love having near-instant response rather than having to deal with all the additional modifications and hassles associated with running a full exhaust just so that the turbo lag can be reduced to bearable levels. If I want to deal with lag, I'd just go with a single turbo.
07-31-07, 02:19 PM
#14
What "upkeep"? I did a silicone hose replacement almost 10 years ago, and haven't touched the sequential system since.
My transition is practically smooth as silk, even at 13 psi. Hardly could be considered a surprise, especially since I've lived with it for over 10 years.
FWIW, I drive in both urban and rural areas (plus racetrack when I can find the time, which has unfortunately been scarce), and I love having near-instant response rather than having to deal with all the additional modifications and hassles associated with running a full exhaust just so that the turbo lag can be reduced to bearable levels. If I want to deal with lag, I'd just go with a single turbo.
My transition is practically smooth as silk, even at 13 psi. Hardly could be considered a surprise, especially since I've lived with it for over 10 years.
FWIW, I drive in both urban and rural areas (plus racetrack when I can find the time, which has unfortunately been scarce), and I love having near-instant response rather than having to deal with all the additional modifications and hassles associated with running a full exhaust just so that the turbo lag can be reduced to bearable levels. If I want to deal with lag, I'd just go with a single turbo.
Also in my friends FD, it's very noticable when the second turbo kicks in. I've read some stories of people spinning this car care of the secondary turbo.
Like I said, there are ups and downs for both setups. If you've been running the same solenoids and same hoses for 10 years you're probably the damned luckiest FD owner right now and you know it.
Also, FWIW means "For What It's Worth"
07-31-07, 07:12 PM
#16
this is my take. I converted from sequential to FULL non sequential to see what the big deal was about. I had a perfectly working sequential system but I was looking for reliability.
Sequential truths that I experienced:
Instant boost at anything above 2.9K rpms. Can be very tempermental. About every 6 months (I drive my car a lot) I would have some kind of boost issue which really sucks. I did a full vacuum hose job at it kept my system trouble free for about 3 years but then the problems began again. At elevated boost levels (above 12 psi) I would get a spike at transition (no harmn done but it bugged the **** out of me).
non sequential truths:
I didn't get 10 psi until I hit 3800 RPMs and supposedly I had all the right mods (SMIC, DP, MP, CB, Streetport). Some people claim they hit full boost at 2.9K here on the forum but I have not met one single person that has been able to do it, and I live in So Cal so there are a lot of FD's runing around. The system also had lag as it wasn't instant boost past 3.8 K RPMs. On the plus side I never had any more boost problems after I went non-sequential
A miscontrued truth about nonsequential: Increase the parallel power band by 700 RPMs and thus make your car faster. (remember 4500 RPMS @ sequential Vs 3800 RPMS non-sequential). True you do increase your power band but you certainly are not faster unless you brake boost... IMO that's kinda gay if you using the same turbos. Another thing to note that those 700 RPMs are only usable during your initial WOT. Most people shift at redline, which brings back your RPMs to above 4500 RPMs WHERE either setup ALREADY HAS BOTH TURBOS RUNING IN PARALLEL ANYWAY! so those extra 700 RPMs are not being used after the initial shift.
My buddy has porsche boxter before I went non-sequential I dusted his *** in every gear at 10 psi. After I went non-sequential and upped the boost to 12 psi I always had to play catch up. Why? the damn lag that's why. By the time I hit boost he was already ahead of me. Don't get me wrong I would dust his *** but like I said I would have play catch up first.
IMO the best of both both worlds is simplified sequential. Only 20 hoses instead of 72 for full sequential, or 6 for full non-sequential. So you keep the responsive factor and yet eliminate the majority of the hoses so it keeps things simple.
Sequential truths that I experienced:
Instant boost at anything above 2.9K rpms. Can be very tempermental. About every 6 months (I drive my car a lot) I would have some kind of boost issue which really sucks. I did a full vacuum hose job at it kept my system trouble free for about 3 years but then the problems began again. At elevated boost levels (above 12 psi) I would get a spike at transition (no harmn done but it bugged the **** out of me).
non sequential truths:
I didn't get 10 psi until I hit 3800 RPMs and supposedly I had all the right mods (SMIC, DP, MP, CB, Streetport). Some people claim they hit full boost at 2.9K here on the forum but I have not met one single person that has been able to do it, and I live in So Cal so there are a lot of FD's runing around. The system also had lag as it wasn't instant boost past 3.8 K RPMs. On the plus side I never had any more boost problems after I went non-sequential
A miscontrued truth about nonsequential: Increase the parallel power band by 700 RPMs and thus make your car faster. (remember 4500 RPMS @ sequential Vs 3800 RPMS non-sequential). True you do increase your power band but you certainly are not faster unless you brake boost... IMO that's kinda gay if you using the same turbos. Another thing to note that those 700 RPMs are only usable during your initial WOT. Most people shift at redline, which brings back your RPMs to above 4500 RPMs WHERE either setup ALREADY HAS BOTH TURBOS RUNING IN PARALLEL ANYWAY! so those extra 700 RPMs are not being used after the initial shift.
My buddy has porsche boxter before I went non-sequential I dusted his *** in every gear at 10 psi. After I went non-sequential and upped the boost to 12 psi I always had to play catch up. Why? the damn lag that's why. By the time I hit boost he was already ahead of me. Don't get me wrong I would dust his *** but like I said I would have play catch up first.
IMO the best of both both worlds is simplified sequential. Only 20 hoses instead of 72 for full sequential, or 6 for full non-sequential. So you keep the responsive factor and yet eliminate the majority of the hoses so it keeps things simple.
Last edited by Montego; 07-31-07 at 07:21 PM.
07-31-07, 07:35 PM
#17
My friends FD had vac hoses constantly flying off when he first got it. The hoses were redone with silicone, but they still fly off from time to time. Not to mention when solenoids start freezing up and stop working the way they should.
Also in my friends FD, it's very noticable when the second turbo kicks in. I've read some stories of people spinning this car care of the secondary turbo.
Also in my friends FD, it's very noticable when the second turbo kicks in. I've read some stories of people spinning this car care of the secondary turbo.
It also sounds like something is wrong with his transition. Transition should be smooth and quick and should certainly not upset the car.
07-31-07, 08:09 PM
#19
2/4 wheel cornering fiend
No, not quite. I know quite a few fellow FD owners in the L.A. area with the "same solenoids and same hoses"-- some with hose jobs even older than mine. You only read about the horror stories on this forum because the people with working sequential systems usually don't bother to write about it.
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Gear2078 (03-31-22)
08-01-07, 02:44 AM
#22
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Keep it sequential. I was pissed off with solenoids failing to and the crappy transition. I got fed up, went and bought New Vac lines from Auto zone, not even silicone, zipped strip every one of them to Rob Baileys solenoids. I start making boost at 2000 rpm, i say about 5 psi, spools up to 10 psi at 3500 and get a full 14 psi at 4500 rpm every freaking day!!!!. But its so dam quick it shocks the **** out of who ever is in my passenger seat every time. Save the money and keep it sequential if you can. It was made like that for a reason, just save up and you wont regret it.
08-01-07, 03:27 PM
#24
I can't, not even once, remember making 15-16psi with out blowing off a vac line somewhere with seq.
But, damn, I WISH I was able to so I didn't have to switch to NS.
Those talking about NS in anything but a FULL NS should keep thier mouths shut.
But, damn, I WISH I was able to so I didn't have to switch to NS.
Those talking about NS in anything but a FULL NS should keep thier mouths shut.
08-01-07, 05:23 PM
#25
Original Gangster/Rotary!
iTrader: (213)
I ran them non-seq, which I regret. The stage 3s sequential are the hot ticket
