i like sequential for the reasons that were already stated, but having looked at the m2 twins vs the non sequential chart i think the non sequential would be a faster car.

 

Greg would probably get me with a midpipe though. I just wanted people to see the seq low end avantage and the non seq mid range advantage.

 

it would only be faster out on the highway at certain rpms/speeds....the jump off the line and the higher pull up top would win the race with gregs current setup.

marshalls turbos are peaked out at 14lbs (reliably) and gregs m2 set has another five-six lbs of range on them due to the efficiency of the larger wheels on the ball bearing set (low temps). marshall is pushing it at the top of the stock turbo efficiency range...gregs are still at the bottom of theirs.

the midpipe helps...like ive said...the m2 set flows tremendously more than the stock set and a cat on mine choked them to the point where i could not boost past fifteen lbs even with the boost cranked to twenty...no matter what I did I could not boost past fifteen lbs on a clean cat. I opened up the exhaust and the difference was night and day.


not to make this an m2 turbo thread....the charts show that the lag on a non seq car is noticable...they also show the strengths of non seq machine out on the highway...ie the race track.

on the street from stoplight to stoplight...where i live...the seq setup is the way to go IMHO.

j

 

whoa i am not saying anything negative about the m2's. let me clarify...judging from those two dyno runs..it seems to me that the non-sequential had a greater average horsepower number. That to me means all things being equal that the non-seq. will win in a race in a straight line. In addition, the power you are making in the lower rpm range isnt really that important as you will only be in the lower rpms for one gear. It will provide an initial jump that should be over came if the race progresses for more time/gears. Obvisoulsy i am simple specualting but that seems pretty logical to me.
Now even after having said that i still remain sequential for the same reasons people already said.
but is a interesting debate. All about preference.

 

yes...and you seem to equate average hp with an overall faster car....however if you were on the highway that might be the case numerically...but anywhere but a STRAIGHT line will be the opposite as those runs showed.



yes..you are correct...its all about preferences.


j

 

who cares about straight line accel, we drive rx7s. I know that will get a few people going.

 

Marshall, that's a nice spreadsheet - nice comparison. I would say for drag racing and highway runs that the non-seq car would have an advantage on 2 cars running the same exact mods - 1 being seq and 1 being non-seq. Non-seq was very linear in power delivery on my car - the front end raised up slowly as boost built and then I was in orbit.

I'm definitely on artguy's side when it comes to immediate power delivery. I drove around non-seq for 2 years and won every race I had - most of the time playing catch-up but passing when I hit top of the gear. Playing catch-up makes me nervous, bacuase the big-end cars I raced (modded LS1s, etc) would pull for a little until I made boost - very similar to a single turbo. If you tune a sequential car correctly, playing with a manual boost controller to open the wastegate sooner, sequential FDs can dominate the street. Non-seq is NOT as fun to drive as sequential...and it goes on and on....

 

My car is NOT the one to use for this comparison. It does not make the kind power it should even if the turbos were stock. In fact, even though it seems to have more power now that I have a PFC tuned by SR on it I am taking to the shop this week to have it compression checked before it goes on the dyno again.
I will post the results of the compression check.

 

We're comparing Greg's

 

Yes I know you are. But someone else mentioned my car. So I thought I should set the record straight on how my car is running. Or not as the case my be. :-)

 

Well that says it all. Not for me. [Especially with a street port]

As far as the BNR's, I think we are all waiting. That could be the thread of the year.

 

Oops, sorry Bill! I think you'll get great numbers when you work everything out.

 

I should have changed that post. And said, if you want instant power, a Rx-7 is'nt for you!

With that said, if you want instant power, get a new vette, or supercharged mustang. When it comes down to it, they will bolth put any twins in there place if your lugging the car. I dunno....when racing who starts out at 2.5k rpms anyways?

Also, as far as my car being maxed out artguy, I feel there's still quite a bit left in her. For one, I'm shure if I where to put a real cat back on there (I'm still running the stock cb), get the car tuned in correctly with a wide band, and run 14+psi, I would'nt doubt seeing 340+rwhp. Then, it would be running at its max. With that said, you realy should'nt say to much about hp down low, until you get it dyno'd. Then you can beat up on us non-seq guys all you want. Until I go single or some BNRs.

CJ, Defender of non-seq turbos

 

No problem Marshall. And I hope you're right.

 

pp13b- well...enjoy your lag homie.



j

 

non-seq sounds good to me. when you're racing, a launch by slipping the clutch at 3000 rpms will still give you plenty enough boost to get you out of the hole on the street, probably with less spin than the seq setup. then after that, when are you gonna be below 4000 rpms anyways? plus if you just want to cruise around...you dont have to be boosting all the time. i found myself boosting a ton going up and down hills. i havnt autox'd my car, so i really dont know the rpm ranges used for that...but im sure seq would be preferred for eploding on exiting the turns.

but theres only one way to find out, which is why i plan on doing the poor mans setup soon.

 

Yer on mistaken my good man.
Rikkis ports are PFS standard issue, nothing unordinarily aggresive about them at all.

See ..


and the exhaust ports were not even done in his car..

 

Rikki's car is somewhat of a freak - 350 rwhp at 11 psi is pretty high but attainable - 325-330 rwhp at that boost level seems more reality but there's always 1 or 2 in the bunch that's freakish - should all FD be compared to this ... NO - each car is defferent and has different tuners.

I'll defend non-seq anyday of the week because of how simple it is and there is a small advantage in the power band. When racing, both turbos are online at 4K-4.5K rpms so they are running parallel anyway. If you don't mind shifting all the time to get power then you won't mind non-seq at all. I think, like artguy, that driving around in screaming low gears all the time (especially since non-seq is incredibly louder than seq) gets really annoying. Simple, but not fun imo

 

You guys make it sound like its a peripheral port or something!

Try the poor mans, then take off 500 or so rpms, to see what a full non-seq setup is like. Not to mention, if you have a power fc, get it on a dyno with a wide band, to pull outs some fuel, and add some timing down low. Otherwise it won't spool as fast, as you'll be running extremely rich down low.

Artyguy, when you ran non-seq, did you do any major tuning to it?

CJ

 

we did clean up the tuning...spent hours on the datalogit getting everything right....but even then i was not happy with the lack of response....sure it made me smile when i did hit the power band....but i was speeding every time that i was smiling...that kind of driving will make you poor in so cal...and jailed...I like tearing around town at low speeds too.


dr strange (I mean rikki and the rikki cronies)....I dont believe you. hahahaha...but that is no matter. Ive seen the dyno sheets and that sure looks like big ports to me. he has big power (relatively) and aint got jack down low.


racer foo....i am below 4k for at least HALF of my daily driving...if not two thirds...i like response..you live in missouri...I drive in so cal and in boston....if you lived there i might ask..when are you ABOVE 4000 rpms. when you are driving by farms and thru the fields on a back hiway then sure..non seq would be a blast. but there are not any of those in a real city. if you want a back road in LA you have to drive for two and a half hours to get out of the city lights...if not more...and even then the traffic is thick as hell.

if you are at the track..sure..when are you below 4k....but if you daily drive your car like that..hahahhahah....well have fun at the shop homie cuz your butt is gonna be broke...and so is your car.

non seq is great for a track car or for the back roads....but in town its a drag.


j

 

it would only be broke if you're trying to race your car all the time, but if its your daily driver, like mine....wouldnt non-seq be better.....since you could drive quite a bit without boosting....which would be better on the motor and turbos. with seq, i find myself always boosting and would think that it is harder on the motor. am i wrong? i know the zipping around is awesome with seq, i love not having to downshift to pass people on the highway, or making a quick exit out of a turn without having to shift....but they way you're talking about reliability, it would seem like seq is gonna be harder on the motor, since it will always be under boost.

and whats all this talk about being less 'streetable'?

 

Some of us actually drive around on the street! . No one cruises on the freeway at 5k rpm. Now, NOT having boost down low in order to have less stress on the engine is interesting logic, I would have to agree, but remember, you can always take your foot off the gas . Its just nice to have the boost right away when you actually decide to put your foot down. However, for anything but autocross where shifting takes up a significant portion of the lap time, I'd have to say Greg's car is faster based on the dyno alone. It has a broader powerband and the peak power is just barely lower. It all depends on what you're going for really. There are PP rotaries out there making 250HP N/A between 8k-10k rpm, slap on 5 very closely spaced gears and they have no problem using the power. The question is, how many advil will it take? One defense of non-seq that I never see is it seems like the turbos would last longer. When they boost, they both are spinning and sharing heat equally, while in seq-mode it seems like you've have some gnarly heat gradients with one turbo flowing air most of the time, boosting up and down, and then another not flowing any air a lot of the time, then suddenly going from nothing to 10psi. Its not just heat that kills internals, its having temperature gradients, ie one spot is hot, another spot is cold, etc. Any thoughts on this?

 

Streetable means a "longer" powerband. A T-88 single turbo FD is not as streetable as a T04e single FD - why? Because you don't hit full boost until 7K rpms - a TO4e you hit full boost around 3800-4K rpms.

A sequential FD will have full boost by 2700-2800 rpms. A non-seq FD won't get full boost until 3500-3800 rpms in 4th and 5th gears - in 3rd gear it's around 4300 rpms and 2nd gear it's over 5K rpm.

I'm not knocking NS at all - it was fine for the time but 5th gear is totally useless - if you have it and 5th trying to pass somebody, it won't happen - even a drop to 4th you have to have your rpms up to atleast 3500 rpms or you areen't going to pull very hard - you have to wait. Waiting sucks - been there done that. Don't tell me to go get a Vette or some V8 because to me a sequential upgraded twin-turbo heavily modded FD can rule the road from any rpm.

 

Kwik, I don't agree with a seq heavy upgraded FD being able to rule the road. There are far to many 10 to 11 second daily driven mustangs around here to even come close. imo. CJ

 

pp13bnos...where the hell do you live?..The oregon raceway??

all these straight runs where you can drive 100mph plus(which you need in order to enjoy your non seq power band) and a pleothera of 10 second fords...sheesh...remind me to stay out of that part of the woods.

lol


j-