Can someone explain the pro's and con's to the non sequential turbo mod? My car has a full open exhaust (downpipe, midpipe, racing beat catback), custom open intake (coming soon), HKS S-AFR, and thinking about an aftermarket SMIC and the new Apexi Ignition timing controller when it becomes available...

Any thoughts? How much of a power gain is this usually over stock? How is low end? And how much exactly can a stock motor handle? As far as I know this is the original motor in the car... But with only a downpipe we managed a 13.5 so who knows....

Anyways, let me know what you all think. Can't really find any information about this using the search function. So please, no flames :P

Thanks
Chuck

 

Do a search for "sequential" or "non-sequential", you will find approximately 100 billion threads that ask this question.

 

From what I've read there is no power gain, it just gets the 2nd turbo spooled up a whole lot sooner .. sorts out the hesitation as the 2nd comes online with stock set-up.

Try www.dontbearikki.com for plenty on the benefits of this.

 

It pulls much stronger in the midrange, but the top end is the same since at high rpms, the turbine's are in non-sequential anyways.

Cruising speeds, the car doesn't have throttle issues either. It's also VERY SMOOTH in non-sequential mode.

 

Hmm.... differing opinions I see. Well, I read somewhere that someone lost power from it and changed back to sequential... That kind of told me it's not a good idea. Am I wrong to have assumed that so early?

Thanks
Chuck

 

If you are looking for low-end power, then you don't want non-seq. Basically, running non-seq is almost like running a single turbo. The main benefit is the simplification of the vacuum lines.

You don't lose power per say, but change when the power is applied. That loss at the low end is applied to the midrange, so it equals out. You don't lose or gain any raw HP at all with going non-seq. It's just when the power comes on that changes.

Some people like it because it makes the power more predicable. Me? I'll keep what little low end I already have...

 

Hmm, ok cool... Another question... Just how much boost is tolerable on a stock motor? And when you want to run more boost, what exactly is required to do so?

Thanks
Chuck

 

People with single turbos have put some serious PSI on the stock seals. The better question is how much boost on stock turbos. The turbos will be your limiting factor, not the stock motor/seals. I wouldn't push the stock turbos past 15PSI, unless you are just begging for a turbo rebuild really soon.

As far as how to increase boost, you need to increase air flow and fuel.

 

Oh really? I was under the impression the motor's couldn't really handle the boost... If it's the turbo's then that's a different story... Why can't they handle much more than 15 lbs? If that's the case I'm going to start playing with the boost and fuel controller....

Thanks
Chuck

 

It's not that the turbos can't handle it, but you'll wear there out that much quicker. Most people are trying to keep their turbos for a while.

Make sure to have an aftermarket IC. Once you start increasing boost, you'll need a more efficient IC. Most people usually recommend the IC upgrade if you plan on using more than 12 PSI on boost, as well as an ECU upgrade.

 

Yeah, intercooler is next on the list. Might put on a water injection kit though for awhile to get us by... As for computer though I'm just planning on using the HKS S-AFR and Apexi Ignition timing controller (when released) for tuning. I figure the stock curves should be fine... it's just adjusting them up and down that will need done. So that's why I'm going this route. Just seems easier to me if a person plans to keep modding. Better than spending a chunk of change every time you do a mod I guess...

Later
Chuck

 

It really depends on what your goals are for the car.. Check the following thread:

https://www.rx7club.com/forum/showth...hreadid=116858

That car (with basically the entire engine bay polished) is local to me. He's putting down a little over 350rwhp using the Pettit ECU. Granted, that's about as far as he will go, but even with reprogrammed ECU's, you can make some serious power.

Basically, if you are looking to be under 350rwhp, then the standard reprogrammed ECU can get you there. If you want more than that, you will have to get something that can be programmed on a dyno.

 

Yeah, for now the fuel and timing controllers are just to simply get us by since I don't feel there is a need for a complete reprogrammed ecu yet. When that time comes we'll do it. But for now we're just doing simple bolt ons. So only minor adjustments will be required... And I plan to do them on a dyno btw. Those stupid autometer a/f gauges are worthless.... So we should be able to get the a/f ratio right to where it needs to be...
Here's another question... What's the most boost you can generally run on pump gas? 91 octane here...

Thanks
Chuck

 

Well, the reason I bought it up is that you are going to be paying about $400 for a HKS S-AFR, then paying for dyno time to tune the thing. You can just get something like a Pettit or M2 for a little more than $400 and not need dyno time and be set for just about anything up to 350rwhp. It's really a much better decision unless you plan on purchasing something like a PFC, Haltech or AEM.

As far as pump gas, I don't know if anyone has really done any tests on it, but I would imagine most people wouldn't go beyond 15PSI, mostly for the reliability of the stock turbos.

 

Oh ok... well since the HKS is bought and paid for (299 through ) I just figure we'll stick with it. Eventually depending on how tuning goes, we'll probably do something different. But like I said, for now this will work.
Sounds like we need to get an intercooler and crank up the boost First I think we're going to compression check the motor though just to see how it's holding up...

Thanks
Chuck

 

fooking lag sucks. mine doesn't reach full boost till like 4200 rpm.

 

What are your mods? Non-sequential is for HEAVILY modded fd's.

 

I LOVE MY NON-SEQ, got me into the 12's so who am I to complain. If you dont have alot of mods though jspec is right, its not right for you. I have about every bolt on possible

 

You and I both

 

alright guys have you seen a difference in your 1/4 mile times since switching to non seq.

 

PM Rikki. He went thru the traps faster...don't remember what happened, but his non-sequential vs. sequential time sheet shows non-sequential as being faster.

 

i am mildly modded. have a cosmo fuel pump. cb/intakes/tuned pfc from sr/greddy smic/dp/blitz bov and a midpipe when i get the cat off. the bolts are stuck.