since turbo'ing my 6port NA motor, i've been enjoying it around town and its a blast to drive!

my only gripe is it's bottom-end power...
it has none!

the car is super slow down bottom and pulls like a banshee on top.

i was at the 1/4 mile with it on friday, and my best runs were 15.2XX at 99.XXmph.

my first practice run was against an older street rod that ran a low 14 at 88 mph.

i was confused at first, but then as the night went on, it was the same story, my 60ft and 1/8 times were terrible (77mph at 1/8) and it just pulled at the end.


i was thinking about a different flywheel (stock now), and maybe installing the twin-scroll on my turbo. i always heard it doesnt make much of a difference but after seeing those times I almost have to believe it does..

 

new diff? high ratio will help low end

 

haven't read much about switchin diff's... ill search around
(FYI its an 88 GXL body and drivetrain)

 

Were you spinning off the line? The heavier flywheel will make for a smoother launch and will bring in boost slightly sooner but it will hurt up top. Sounds more like a tuning problem more than a mechanical problem. Kinda like you're pig rich out of boost.

 

definitely check out getting a 4.3 ring and pinion on there if possible, that should help a lot

oh and NOS

 

My NA-T has tons more power everywhere. But I built it myself. Also you can't womp your foot to the ground on an NA-T ... you have to ease onto it for the best spool. You do have your twin scroll solenoids hooked up correct? (guessing your s4)

 

240whp and you ran a 15.2??? i ran that in my old 150hp n/a

 

didnt spin at all, i launched at 3-4k and feathered the clutch out just right to minimize wheelspin.

not hapnen lol

i built this myself too, but i dont have the twin scroll on at all.

yeahhh tell me about it...

 

what 60' and q/8th times did you have?

 

this was my best run, all other runs were 10ths of a second off of this, (ie. couple 15.2XX, and couple 15.3XX)

60'--------2.678
330-------6.956
1/8--------10.188
MPH-------77.84
1000------12.917
1/4--------15.197
MPH-------99.41

 

yea i 2.6 60' is pretty bad i would say strip it out for the strip and get some used slicks/drag radials (1.9-2.1 60' should be easy)

what rpm's are ya launching at?

 

i launch at 3-4k and feather the clutch out just right to minimize wheelspin.

if i drop the clutch from anywhere above 3K it wheel hops bad and i lose all RPMs

 

What size turbo?

 

stock s4, twin scroll not hooked up

 

if it's stock turbo then you should have the twin scroll hooked up. normally it is only removed when upgrading the turbo to a hybrid or something. Stock turbo will spool better with a working twin scroll though than with it removed.

 

i know it WILL improve spool, but ive always read it was a marginal difference...

guess i'll hook it up and see how much of a difference it really is

 

is your diff mount bad, you need to be able to launch higher in the powerband.

 

as far as i know my diff is fine..

what would make you think its bad? or how would i know?

 

mate test to see what max. revs you just end up spinning the rears (prob about 6K) when you know, drop it back 500 and try and launch at that. (assuming it wont bog or spin)

I think your just boggin it off the line. The track will alway grip way more then the street so dont be afraid to launch at med-high rev's.

Is your diff the old 6 post NA diff ? if so your ratio''s shouldnt be to bad.

 

dunno what diff it is exactly -- stock S4 GXL diff.... thanks for the advice, ill try that out next time im there

 

Because of the wheel hop you are experiencing at relatively low rpm launches.

You should be able to launch at 5k with no wheel hop.

I know my car never wheel hops, if I launch too high it just spins the tires.

I launch between 4k and 5k and it seems to launch the best when i spin the tires a little.

 

yea because of the wheel hop (could also be shocks or something else) its very common on FC for it to go out. I let it go around 4.5k when at the strip

 

ill check out my diff soon and see whats up with it..

and that shocks comment makes sense too--since im still on stock suspension

 

Car needs a better driver

With a 99mph trap speed the car has potential to run low 13's......maybe high 12's a couple times.

BTW - its a rotary, it has no low end torque You're in the best scenario for a low end torque wankel being a high(er) compression engine with N/A irons...

Tuning could be off, but it must be making decent power to trap 99mph. So practice, it'll come.


You should be hitting a 2.0 60ft at the slowest. That alone would probably translate into a low 14.....

I could cut 1.7 60ft's on my old stock turbo, 2.6 sounds like you've got 3 guys pushing you out of the hole Rev that thing up to about 6K and let er GO!!

 

is the rear end ratio of a N/a that much bigger then a T2?