I agree. And you’re right, it’s not going to win any dyno-sheet contests, or enough to do burn-outs until the tires explode. But 300 whp is about 350 FW and on stock sequential that’s an absolute hoot on the street. And it will also stay along side, say…a new 1LE from ~40 mph to ~ 120 mph. And despite its age, it will turn better and probably brake as well.
I’ve ridden in others and so glad I fought temptation a number of years ago and kept stock sequential.

 

I can't disagree with Montego because that was his real life experience but I can say as a fact that is NOT how a full non sequential set up is supposed to respond. Something was off. I've had this discussion with someone else and they did the non sequential mod and had a similar experience. I expressed to them that Something was wrong as well. I forget what happened exactly but the issue was found and it was something of a holy experience after that.

I am currently taking an all stock fd and doing a proper full non sequential set up on it now. Once its done, we will be going to the dyno and the data will speak for itself. The "lag" that people are describing is not representative of what its supposed to be like and i will show it.

For goo goos and gah gahs, I may even do a really nice youtube video on the comparison using a 40k mile all original fd vs this converted one im doing. I think it would be a great data set.

 

You realize I’ve personally converted over 100 FDs to non-sequential from stock to 18-19lbs of boost, correct? He described it perfectly. You are going to be very disappointed when your dyno sheet shows you gave up 100rwtq for about 1500 Rpms to gain 8-10 peak HP above 6800 Rpms. There is no secret to the results you will get, it’s literally been done thousands of time in the US alone.

 

While I may not have done the conversion as many times as you, I have done quite a few myself. Seeing as how everything is mostly the same from car to car you don't need to do it a great deal of times to see the repeatable results. I'll come back with some data in about a month or so. We can poke at some graphs instead 🤔🤔

 

Look forward to see the graphs! Would be cool to see, honestly don't think there are as many comparative dyno graphs as I previously thought from my searches.

Unrelated, but this is a super cool thread on the potential of sequentials. Don't think I'll ever push this much power, but really cool nonetheless:

https://www.rx7club.com/time-slips-d...sight-1108026/

 

My 3800RPM boost threshold was not only confirmed by the forum but by my mechanic (Southern CA rotary shop and they see plenty of FD's) and Brian himself from BNR turbos (I contemplated BNRs). But also I have never seen any proof that a non-sequential car has a comparable boost response to a sequential one. Just arguments with nothing to back it up. I've even asked for proof, like a video at the very least but nothing.

So I can't tell you how much I look forward to someone finally proving it and two simple WOT cell videos should do it. One from 2500-5000RPMS and the other from 3500-5000RPMS, both showing the RPMs along with the boost gauge. Thanks

 

Everyone with Non-Seq is really going to have their feelings hurt if they try to overlay the Torque curve with that graph. That is a rare example but shows the potential of pushing the envelope.

 

Can the video be shot while driving up hill, in 5th gear while pulling on the ebrake a little? Lol

 

This is an interesting conversation, so I did a bit of googling.
Non-Sequential Turbo Conversion
From what I know of @cr-rex car, he has opened up the intake and the exhaust. This write up seems to back up his claims that they aren't as laggy as people think. That said, they do mention it will be laggy if you are running a stock intake/exhaust.

 

Ive personally dynoed 8-10 non-sequential cars that were stock port with full conversion, stock port with poor man non-sequential, small street port full conversion, massive street port full conversion etc. We are going to learn and see nothing new here unless he sprays a small 25-50 shot of nitrous. Thats the only thing that will make a difference over the countless others before this.

 

Ohhh I've been waiting for that update with that setup!

 

i understand.... not going to contest what you experienced but it certainly conflicts with what i have experienced lol. i'll bring the data here and we can discuss from there. i'll make a new thread about it and link it. very excited to be able to end this finally. non-seq is better and i will prove it. i will make sure to do the pulls in those rpm ranges with the relevant data as well. any other specific requests?

 

To make this scientific, we should get data logs, not just cell phone video that's hard to correlate. Logs will show the data raw.

 

shaky vertical flip phone video is the only way i know how to do things.... sorry but you'll just have to deal with it

 

Worked perfect. I had to pull the stock port reman as the front cover leak got too bad to ignore any longer. The small street port motor is already in the car. I’ve just got to finish making the modified wastegate actuator bracket. I didn’t like how I had to make it work with the one BW sends.

 

After all these years, this may be one of the most accurate statements I’ve ever read on this forum. I still own and drive a well sorted single turbo fd, but my 330 whp sequential is still my favorite choice. Nothing like a well sorted sequential FD, nothing. I was also wondering how that stock port, efr turbo on the Pettit ecu did. Looks like a hoot.


~ GW

 

For the record I'm not contesting what you are claiming, this is truly academic for me. You have to understand that it is quite the hot topic issue and not only have people been arguing this for two decades now but mazda's engineers setout to design a fast responding turbo system and this is what they ended up with. 72 vacuum houses where one primary turbo spins first while the second turbo is pre-spooled in order to instantaneously come on line at a higher RPM. So again if you can provide proof that would be really cool to put this to bed.

Obviously the most data you can provide the better. Dyno graphs, ect is best. But at the bare minimum it should have the videos of what I requested. It's a very easy request, grab a friend and have him/her film from the passenger's seat and make sure they capture the RPMs and boost gauge. It takes 5 minutes tops.

BTW there is a reason why I said those specific ranges. The first one is a boost threshold test, where WOT is applied at 2500RPM to see the boost rise slowly and determine exactly where 10psi is achieved with regards to RPM. The second range where WOT is applied at 3500RPM is the boost lag test. I chose 3500RPM because at that point your boost threshold should have already been achieved (but is still below the 3800RPM mark otherwise there's no point) and we should clearly see how fast your setups gets to 10 psi. I chose 5000RPM as the end of the WOT runs only because is past 4500RPM (where a sequential turbo comes on line) so after that there's no point of going to redline for boost threshold/lag testing. That is unless you want to show how solid your boost response is until redline but that is up to you. Non-sequential systems are known for their stability anyway.


lol no brake boosting either. Plus the boost gauge tells all. Meaning the gauge should be either at zero or at vacuum prior to going WOT.

 

If non sequential really was that good, there's no way Mazda would have put a sequential system on the FD. It's expensive and complicated, think of the extra assembly time just hooking up all the lines. Anyone saying there's not much difference never drives below 4k. Opening up the intake and exhaust will have a positive inpact on the sequential system as well, like for like there's no comparison.

 

The other issue with many of the FD videos is that for the US market where most of the videos are made, the RX7 stopped in 1995 but it continued to be improved elsewhere. For 96+ JDM spec cars, the complexity of 72 vacuum hoses is vastly simplified with most of the rats nest replaced by a single solenoid box and the downpipe/pre-cat heat issues created by US-emissions requirements is non-existent. Then you get the cooling / airflow improvements in the 99 spec and 280ps and 17" wheel versions with improved turbos, improved exhaust, better oil cooling, bigger brakes, 4.3 final drive etc, then 4 wheel ABS with electronic braking distribution in 2001.

 

Hey man, you don't have to be mean about it

(Jk)

 

Series 7s are available to import to the US now under the 25yo rule anyway!...and half the US delivered FDs already have the 99 spec front too!

 

Love how this thread turned into a sequential/non-sequential debate thread .

IMHO, non-sequential died as a viable option years ago. People originally did it because there were VERY few single turbo kits, they were expensive, and they were beyond laggy - like NO boost until 4000 RPM.

It was also an option back when you could pick up a ratty but running/driving FD for $10000 or less. You'd have a ratty under-hood situation going on and instead of trying to figure it out you would just rip all that out and go non-sequential and no emissions.

Then you would also have guys running chipped ECU's and/or PFS Purples that would see literally 100hp spikes when the second turbo hit. If you hit that transition in a corner you'd be doing a donut in short order.

The sequential system has been documented to death. Mine has been nearly zero trouble for the 17 years I've owned my car, the only problem was one solenoid going bad. That's it. If you can't spend the time or the brain power to fix it that's on you.

There are so many amazing single turbo options now that if you want more power you can have a fat power band. The 8374 is freaking amazing, I was really impressed with how it hits down low just like the twins then pulls like a freight train to redline. That is THE way to go IMHO if you want something more.

I also maximized my setup for reponse - I drive my car around town and once a year on the Dragon so I love having that down-low power. 99 twins at 14psi and the RX-8 4.44 ring and pinion and an AVC-R boost controller. The boost comes on strong and hits easy driving around at low RPM. @djseven has driven my car and can speak to how it runs.

All that said, there's really no justification to do it. You lose power where you need it driving around town for a tiny gain up top and you get to remove some solenoids. That seems like a poor trade to me.

Dale

 

Really interesting thread here gents and I appreciate the turbo feud.

I have heard many people say this and am trying to focus my build that way. I started a more specific thread related to this issue here https://www.rx7club.com/3rd-gen-gene.../#post12500097 . The basic question is, with todays tech is it worth it to go single if you want to keep the car at around 300 rwhp?

 

300whp can go either way, depends on how you use the car. As a semi daily or cruiser type normal use car, keep the twins. If you drive hard regularly and suffer from heat soak, single is the way forward. However saying you only want 300whp I'd say keep the twins because you are probably a less punishing driver

 

300whp can go either way, depends on how you use the car. As a semi daily or cruiser type normal use car, keep the twins. If you drive hard regularly and suffer from heat soak, single is the way forward. However saying you only want 300whp I'd say keep the twins because you are probably a less punishing driver