iluvmy3rdgen

I think that may be because of the fact that you cannot even compare the torque of a v-8 bottom end to the bottom end torque of an turbo motor.

jimlab

So how long does it take to accelerate from 3,000 to 3,500 when in the proper gear? Besides, from 3.5k to 5.0k, non-sequential OWNS.





If you wanted to drive around town in 4th gear, then yeah, I could see it being a problem, but in 2nd or 3rd??

My engine makes more torque at idle than yours does at peak.

I didn't have to change my driving style AT ALL converting to non-sequential. I think the people whining either haven't driven a properly converted car (evidenced by the fact that they can go back to sequential afterward) and/or have catalytic converter(s).

DamonB

The majority of people talk themselves into going non-seq for performance reasons and that's what they tell their friends. The real reason for most is that they have some sort of boost problem and are unwilling or unable to properly diagnose it. Yes, the stock system is quite complicated and can be failure prone if not properly maintained but it does a great job in doing what it was designed to do.

I had one boost problem that I myself caused when I added silicone vac hoses and forget to connect a hose. I had another boost problem when the precontrol solenoid broke and I replaced that. I had one other when the lower ic hose split. So in almost 60,000 miles of daily driving and dozens of race events a year I've had two real boost failures. One a result of the precontrol solenoid and one a result of an old stock ic hose splitting. My stock system works fine all the time and I drive the **** out of it.

Fd3BOOST

iTrader: (7)

Holy ****, I actually agree with this post. Im speechless.

Tom93R1

iTrader: (2)

I still have never seen anything that even hints non-seq being faster. Please qualify this statement instead of non-seq fan boys bashing everybody who likes their seq twins.

SleepR1

If your car is street-driven, a properly-functioning sequential twin turbo system is MUCH better, than the non-sequential mode

djseven

iTrader: (56)

I dont think anyone has gone 10s on sequential. I know someone has on non-seq. NOt solid proof but it is a fact.

David Jerome

turbojeff

iTrader: (30)

Jim's post shows about a 30-50lb ft loss of torque (from 2650-2700 rpm to about 3200 rpm. 25 lb ft of torque loss at 3500 rpm.

Torque is not equal until ~3800 rpm, so below 3800 rpm non-seq gives it up to seq.

Jim's graph does not throttle response at any rpm.

If you watch your tach while driving around and see that you don't spend much time in the <3800 rpm range you might like non-seq. If you do then you might not.

Tom93R1

iTrader: (2)

That does it for me, I am now a firm believer that non-seq is the way to go.




Somebody has done 6.5 is an old school VW but that doesnt mean that old school VW's are faster than twin turbo rx7's.

cewrx7r1

iTrader: (2)

In first gear from a rolling stop at 2000rpm I have too much power for floored throttlle acceleration and that is with non-seq, stock ports and AVS ES100 255/40-17 tires. Once in second, I am past 4000rpm and the tires will also spin some. This happens at 13PSI boost, and worst at 15PSI boost.

So where is my lost of torque? I only loose it if I am too lazy to shift to a lower gears when revs are low. Like I said, you either have a manual or auto trans
behavior or liking.

So who is full of crap?

See 15psi boost dyno in 94F shop ait temps.

djseven

iTrader: (56)

Thanks for taking that out of context. Im pretty sure boostd7's setup that went 10s was a streetport with stock twins on pump gas without nitrous so your comparison like your comment is totally irrelevent. Like I said there is no proof that I have read that non seq is faster. However, if you look at the top guys on this forum running low 11s you will see they have converted to non seq. I am no genius but you would think they have done this for a reason. A lot of these guys are serious about drag racing so I doubt they converted so they wouldnt have boost issues and to make things more simple. Just common sense really until someone proves otherwise.

David Jerome

turbojeff

iTrader: (30)

Compare your dyno sheet to Brad Barbers, looks like you have a loss of torque (Brad had 210-215lb ft from ~2700 rpm).

Your graph shows 200 lb ft at 3500 rpm and very similar to Jim's post of non-seq.

cewrx7r1

iTrader: (2)

Brad has 210ftlb from 3000 to 4500.
I reach 210ftlb at 3600 then outrun him reaching 275ftlb at 4500, this was 15PSI.
From a old 12psi run I still had 210 at 3600 but only 250 at 4500, still better above 3600 than his.

What does that mean, he gets one car length on me then he see my tail. That is if
I start that low rpm in 4th or 5th.

Looks like he has a loss of torque from 3600 to 8000.

turbojeff

iTrader: (30)

His torque after transition isn't that different from yours. So you lose some torque on spool up and he loses some before tranistion.

YEP, 15psi produces more torque than 11-12 psi.

YEP, seq's power has the typical flat spot before transition and corresponding jump after 4500 rpm.

Has PFC tuning reduced the amount of spike? I'm no PFC expert so I really don't know the answer to that question.

Depending on where and how you drive your car seq might be for you or non-seq might be for you.

neit_jnf

iTrader: (17)

can the transition be smoothed out using two boost controllers, one for prespool and one for max boost?

iluvmy3rdgen

My pfc is setup for stock twins at 14 psi with lots of fuel, fmic, full exhuast and intake and fuel pump. Will i significantly have to change my maps for non-seq? Also, i have been reading that the precontrol flapper gate is to be welded open? Can it just be removed?

Mahjik

iTrader: (1)

If your sequential system is working properly, you should only barely notice the transition.

Sonny

I think the transition is exaggerated on some of the aftermarket ECU's like the M2. When the secondary comes online, it really lays you in the seat. Very cool for going straight and impressing people...makes me a little nervous when I'm cornering!

Sonny

cewrx7r1

iTrader: (2)

Since non-seq build less boost below 4000rpm, you can add a little more timing
and lean out the fuel and this helps to bring the power back up some.

matty

chcuk i think your traction problems arent a function of power but a function of your suspension set up. What suspension mods do you have?

i had similar problems when i had ten yr old rubber with similar power to you but since i switched to toyo t1-s its been gone.

BATMAN

I think his traction problems are a function of the shitty tires.

I run A032r 275 in the rear and it works plenty fine with my seq twins.

tcb100

The key difference in quarter mile times is not sequential versus non-sequential, although the lack of the dip before transition is probably somewhat helpful.

The key issue is midpipe versus cat.

Boostn7 is the fastest twin turbo car ever and Kevin Wyum is a very very close second,. Both are non-sequential but neither ran low 11s with a cat.

So it's cat versus midpipe. I like the sequential responsiveness, I think there are risks running a midpipe with sequential set-up and I am not hardcore enough to swap exhaust systems before every Maryland emissions test - leaving me with a high flow cat and with the sequential set-up.

The only obvious advantage is simplicity, but good tuning, a vacuum hose job & a check of solenoids & sensors on thse old cars solves most of those problems.

matty

so how come i trap 116mph with all the bolons w/mp @ 15 psi and they run 120mph traps?

Mahjik

iTrader: (1)

Not at all. RTS3GEN on the forum ran 11.77 (Pettit ECU, stock injectors) in the 1/4 using the sequential setup and a midpipe, ported motor (without a ported wastegate).

Mahjik

iTrader: (1)

Not at all. Using the Pettit ECU, my transition was barely noticeable (when the car was running that is). If your secondary is kicking in that hard, you might have something not functioning 100% with the sequential system.

BTW, I'm not just saying that because "I was used to it". Other people had driven my car and commented on the same thing (who were non-seq people).