paul1985

iTrader: (3)

I was wondering how much extra hp is gained by going non sequential with porting on turbos and block with extra motor mods.

j9fd3s

iTrader: (3)

welcome to 1998!

the answer is zero. having the turbo sequential or not doesn't change peak hp, you just don't have the spike at transition.

MOBEONER

iTrader: (18)

One of the good thing of going non sequential is simplicity.

paul1985

iTrader: (3)

thanks for the info. whats the max psi that i can get out of the stock turbos? i have heard 17

MOBEONER

iTrader: (18)

13psi max. You can push 15psi or more but they will over work them selves to death quickly.

JTurtonRX_7

only reason to go non seq is if you are tired of the random boost spikes and random no boost issues.

Ive been poor mans non seq for years now and I would never think of going back.

I would never go over 14psi on stock turbos you are just stressing everything to much and blowing lots of very hot air. You are just asking for trouble up there.

Kotetsu

Transition only occurs on zenki models because of the crapy "rats nest" solenoid assembly. If you change this for a kouki valves assembly you won't even feel the transition (I know I have taht system on my own car).

Besides killing the sequential system is good for race cars that need to remain in OEM setup. Super Taikyu FD3S all are set with normal (non sequential) turbos and intercoolers. They deliver 350hp with just 1 bar of boost.

sequential is good for road use (at least here in Japan where we have touge roads) and it's smoother than non sequential or single turbo setups.

normal turbines will bear 0.9 to 1.0 bar of pressure but above that you'll kill'em quiclky and the OEM boost control will fail too.

Mahjik

iTrader: (1)

On a properly functioning "rats nest" along with properly functioning actuators, the transition is basically un-noticeable. It doesn't have anything to do with the "black box" that was used in the later models.

Kotetsu

Well with a good condition rats netst I could only agree with you. However it actually DOES have something to do with the "black box" especially because it's a lot more reliable. You can of course overhaul the whole assembly and have a perfectly running system without replacing it for a kouki version that's right.

The greater benefit of this change is the better reliability. My pro tuner did it on his own car (which became mine) and that's for good reasons.

Mahjik

iTrader: (1)

I have yet to see anything which demonstrates the black box being any more reliable. I see them having solenoid failures in the same time frames as the older rack. The main difference being the "box" being newer so the failures starting popping up later but the time of failures from what I've seen are nearly the same (and the same solenoids with problems).

Kotetsu

Well consider I said nothing then. I don't want to argue about that.

I'll still keep to my Japanese tuner's advice on this matter though.

no_more_rice

Actually, a properly welded and ported non-sequential manifold will easily outflow the stocker, and produce a liquid smooth boost response.

Send your manifold to David Garfinkle for his "rich man's non-sequential" conversion, and get the manifold ceramic coated.

j9fd3s

iTrader: (3)

agreed. the ECU is also way better after well, we stopped getting the car

DaleClark

iTrader: (55)

Part of the problem with the spike in transition is from the stock transition point. I think Mazda actually tuned it so you can "feel" the transition. If you're a new car buyer, you want to feel that second turbo come on, that's a big sales point.

On my PFC I lowered the transition point of the sequential system. Doing so makes a butter smooth power curve, I can't feel any sort of spike or anything. I just hear the car get louder when the turbo control door opens .

If you still have a big spike with sequentials, you're doing it wrong. A good aftermarket boost controller and a PFC will solve that problem REAL fast. If you're still playing with the stock boost control and the pills, you will have goofy spikes and weirdness, that system is only good for STOCK cars.

Dale

Kotetsu

Sorry to insiste but I don't think so. Actually I had a zenki ECU but with a kouki solenoid assembly and felt no transition.

Anyway it's not reaaly the point because these parts aren't available outside Japan and it requires to modify the electrical harness to fit them.

Eiji

iTrader: (1)

I've recently had my sequential turbo FD tuned. Only power mods are a full 3" exhaust and PFC. It also has a fresh set of vac lines, Viton check valves and a fast acting IAT.

It is a 01 Type RZ, which I think is a kouki?

Below is my dyno sheet. I'd like to hear how it relates to what you guys are talking about re the spiking and power delivery.

FWIW I love the power delivery, I've got power very early and if I decide to keep the pedal down, it only gets better.

theorie

iTrader: (31)

really any good performance shop can do this job.

when i did my rebuild i went "rich man's" non-seq but did a little extra. i still removed all of the butterflies, welded everything that needed to be, and ceramic coated my exhaust housings, but i also port matched the turbo manifold exhaust housings to the exhaust ports on the motor and also modified my efini Y pipe to insert a splitter.

my setup definitely has much better flow compared to the seq setup w/ all the butterflies and extra garbage. we flow-benched the y-pipe and it flowed much better than the stock y-pipe also.

here's an 'in progress' pic of the turbo manifold porting...didn't take a final shot


also here's the y-pipe with the splitter mod:


and here's my dyno graph with this non-seq setup:


cheers.

Kotetsu

Here is my (humble) chart with a sequential setup (kouki solenoid bloc):



We clearly see when the secondary kicks in but there is no loss at the transition.

boost is only 0.9bars and I run with an Apex'i Catalyzer.

If you want more than 350hp you shoul go for non seq or single I think...