Mods to wake the 928 S4 up a little
07-13-2007, 02:09 AM
#17
Three Wheelin'
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Originally Posted by Dan87951
I have a 88' 928 S4 auto and also a boosted 944 that will lay down a solid 270HP and 300 torque at the wheels (stock turbo still) and the 928 feels a little sluggish on the bottom end compared to my 944 Turbo. Don't get me wrong when you are on the highway and nail it, boy does it move. Its almost like Porsche put such tall gears in the 928 that it hurt its bottom end everyday city driving performance. I just ordered a RMB exhaust, K&N, and Autoauthority chips and hoping to gain some of that lown end speed back. I have heard the chips don't do much for these cars like the 85-86 but every little bit helps, right? Any other ideas other than a supercharger (currently way out of the budget)
Thanks
Thanks
Dan the Pod Guy
07-13-2007, 02:17 AM
#18
928 Collector
Rennlist Member
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Don't bother with chips, kickdown switches and snake oil. If you want to wake your auto up, make sure the bowden cable is adjusted right and you have no vacuum leaks, so your tranny shifts at redline and not before, and so it downshifts fast when you put your foot down. Also, drive with the shifter, you would in a 5-speed, so why not in your auto? You won't believe the difference.
Lastly, put a crossover in.
After this, tere is really nothing you can do to pep the car up, but I think you won't recognise your auto after these few inexpensive changes.
Lastly, put a crossover in.
After this, tere is really nothing you can do to pep the car up, but I think you won't recognise your auto after these few inexpensive changes.
Originally Posted by Dan87951
I have a 88' 928 S4 auto and also a boosted 944 that will lay down a solid 270HP and 300 torque at the wheels (stock turbo still) and the 928 feels a little sluggish on the bottom end compared to my 944 Turbo. Don't get me wrong when you are on the highway and nail it, boy does it move. Its almost like Porsche put such tall gears in the 928 that it hurt its bottom end everyday city driving performance. I just ordered a RMB exhaust, K&N, and Autoauthority chips and hoping to gain some of that lown end speed back. I have heard the chips don't do much for these cars like the 85-86 but every little bit helps, right? Any other ideas other than a supercharger (currently way out of the budget)
Thanks
Thanks
07-13-2007, 02:20 AM
#19
Rennlist Member
Dan, better go back and read the gearing posts. on street tires and if you are not drag racing from a start, there will not be much difference in overall acceleration. it really depends on where you spend the time(or speeds) accelerating!
on a rolling start, it would be unnoticable to have one vs the other 2.2 vs 2.75 or 2.64. remembrer, the actual gear ratios are less than 15% difference, not the full difference of the ring and pinion. here is a hint, if you want to accelerate faster, use the higher rpms closer to max HP! redline at shifts!
Now, if you stay automatic and have the 2.2 and the wide gears, a 2.64 would work better for most street driving, i agree.
for the most bang for the buck, get the GT cams or modify some 85s to fit the S4, or the X pipe. seen some good results for that.
generally, the gains i saw for headers, a tune up, and open exhaust, along with venting the air box, I saw near 40hp. 290 to 330rwhp
mk
on a rolling start, it would be unnoticable to have one vs the other 2.2 vs 2.75 or 2.64. remembrer, the actual gear ratios are less than 15% difference, not the full difference of the ring and pinion. here is a hint, if you want to accelerate faster, use the higher rpms closer to max HP! redline at shifts!
Now, if you stay automatic and have the 2.2 and the wide gears, a 2.64 would work better for most street driving, i agree.
for the most bang for the buck, get the GT cams or modify some 85s to fit the S4, or the X pipe. seen some good results for that.
generally, the gains i saw for headers, a tune up, and open exhaust, along with venting the air box, I saw near 40hp. 290 to 330rwhp
mk
Originally Posted by Podguy
Buy heinrick's five speed and do a conversion. If that is too much find a differential from an 89 auto and stick it. The 2.20 gears are killing you.
Dan the Pod Guy
Dan the Pod Guy
07-13-2007, 07:23 AM
#20
+ 1 on intake leaks. Also, a tired MAF will degrade performance without affecting drivability. Esp. in the low to mid range. I replaced mine at 64K, they do get tired.
A smoke machine will quickly pinpoint leaks. Putting mods on your car without bringing it back to spec first is a crapshoot. Tune up, O2 sensor, new wires. The usual.
A smoke machine will quickly pinpoint leaks. Putting mods on your car without bringing it back to spec first is a crapshoot. Tune up, O2 sensor, new wires. The usual.
07-13-2007, 08:38 AM
#21
Track Day
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Originally Posted by Daniel Dudley
+ 1 on intake leaks. Also, a tired MAF will degrade performance without affecting drivability. Esp. in the low to mid range. I replaced mine at 64K, they do get tired.
A smoke machine will quickly pinpoint leaks. Putting mods on your car without bringing it back to spec first is a crapshoot. Tune up, O2 sensor, new wires. The usual.
A smoke machine will quickly pinpoint leaks. Putting mods on your car without bringing it back to spec first is a crapshoot. Tune up, O2 sensor, new wires. The usual.
07-13-2007, 09:49 AM
#22
Rennlist Member
Dan87951,
Do you use the first gear start in the S4? It DOES make a difference!! For improved acceleration from a stop light, etc., pull selector to 2 when stopped. After accelerating to desired rpm in 1st, move to 3 and immediately back to 2. That shifts to 2nd gear and holds it there. Again, when you reach desired rpm's, shift to 3 (get 3rd gear now), and repeat into D when desired.
The '94 and '95 GTS's have a revised shifting map that provides 1st gear start with ~10% or more throttle application in D. Do a search if you are interested, as it is apparently retrofittable.
Gary Knox
West Chester, PA
Do you use the first gear start in the S4? It DOES make a difference!! For improved acceleration from a stop light, etc., pull selector to 2 when stopped. After accelerating to desired rpm in 1st, move to 3 and immediately back to 2. That shifts to 2nd gear and holds it there. Again, when you reach desired rpm's, shift to 3 (get 3rd gear now), and repeat into D when desired.
The '94 and '95 GTS's have a revised shifting map that provides 1st gear start with ~10% or more throttle application in D. Do a search if you are interested, as it is apparently retrofittable.
Gary Knox
West Chester, PA
07-13-2007, 10:06 AM
#23
Nordschleife Master
Thread Starter
Originally Posted by Gary Knox
Dan87951,
Do you use the first gear start in the S4? It DOES make a difference!! For improved acceleration from a stop light, etc., pull selector to 2 when stopped. After accelerating to desired rpm in 1st, move to 3 and immediately back to 2. That shifts to 2nd gear and holds it there. Again, when you reach desired rpm's, shift to 3 (get 3rd gear now), and repeat into D when desired.
The '94 and '95 GTS's have a revised shifting map that provides 1st gear start with ~10% or more throttle application in D. Do a search if you are interested, as it is apparently retrofittable.
Gary Knox
West Chester, PA
Do you use the first gear start in the S4? It DOES make a difference!! For improved acceleration from a stop light, etc., pull selector to 2 when stopped. After accelerating to desired rpm in 1st, move to 3 and immediately back to 2. That shifts to 2nd gear and holds it there. Again, when you reach desired rpm's, shift to 3 (get 3rd gear now), and repeat into D when desired.
The '94 and '95 GTS's have a revised shifting map that provides 1st gear start with ~10% or more throttle application in D. Do a search if you are interested, as it is apparently retrofittable.
Gary Knox
West Chester, PA
Thanks for the info. The car definitely starts off in first gear already. If I put the selector in D and mash my foot the floor so it kicks in the kick down switch it will definitely take off in 1st gear. I think its more of a gearing issue really. If im at 65mph and nail it, no doubt it puts me harder in the seat than taking off from a dead stop. Which is what the car was designed for.
07-13-2007, 11:00 AM
#24
Rennlist Member
I believe the GTS kickdown retrofit is only good for '89-newer cars. I think Borland found that the '88-older does not have the same sensors that the GTS dynamic kickdown needs to do the job.
05-10-2018, 12:16 PM
#25
Advanced
Engine mods.
I am mostly a 911 guy just getting my feet wet it sharky waters😉
I like the idea of the GT cams. Is there other top end stuff potentially? I didn’t hear any talk about the supercharger which are best?
Does MoTec have any applications?
I like the idea of the GT cams. Is there other top end stuff potentially? I didn’t hear any talk about the supercharger which are best?
Does MoTec have any applications?
05-10-2018, 12:17 PM
#26
Rennlist Member
Like real HP, or measured in Kiborts....that seems...a lot for a simple exhaust mod.
Ive run this,...I didnt go from 280rwhp to 320..maybe, 8?
05-10-2018, 12:22 PM
#27
Rennlist Member
Me. I sold my corvette, my RX8..I wanted a GT car.
Camaros are also F/S that make all the right noises and do all the things your 928 wont do well...because its a GT car...you can step into 2.54:1 gears...but its still a GT car.
Kinda like all the guys that bought the RX8 for the HP numbers, but forgot rotaries have no torque...and you have to know how to drive a car to actually use and enjoy it..the returned them and bought Camaros and Mustangs.
Im not sayin you're wrong, do as you wish, just makes the rest worth more everytime one leaves it's stock form...and I'm OK with that.
And Im approaching 50..so I gotta work on my 'get off my lawn' growl too.
05-10-2018, 12:25 PM
#28
Rennlist Member
"Do you use the first gear start in the S4?"
Now...I dunno what to get from this...but when I was having real mystery trans issues, Greg Brown always said this:
"You dont start in 1st gear all the time do you..." If The Dog from Game Of Thrones asked you that..you would pause.
With...that look...which makes me feel that this is not something you should normally do...or maybe its just the specifics to -my- transmission because it has a this and that that most dont have.
Just food for thought.
Now...I dunno what to get from this...but when I was having real mystery trans issues, Greg Brown always said this:
"You dont start in 1st gear all the time do you..." If The Dog from Game Of Thrones asked you that..you would pause.
With...that look...which makes me feel that this is not something you should normally do...or maybe its just the specifics to -my- transmission because it has a this and that that most dont have.
Just food for thought.
05-10-2018, 12:57 PM
#29
Pro
Hi Dan
Great discussion and exactly what I thought needed done when I bought my 89 S4.
First things first you should ensure your S4 is in good health, by that I mean that engine sensors and MAF are all working as they should. Included in that list should be the operation of the inlet manifold flappy.
Without these all working properly the car will loose lots of HP.
With a completely healthy S4 a good approach in order of expense / effort is below. Changing the cams is the only open heart surgery required which could be combined with a water pump change. This first level can get you close to something like a 60 - 70 hp bump
x pipe
headers
shark tune
GT cams
Next level up before forced induction or stroker
higher lift cams than the GT cams
Inlet manifold changes
Great discussion and exactly what I thought needed done when I bought my 89 S4.
First things first you should ensure your S4 is in good health, by that I mean that engine sensors and MAF are all working as they should. Included in that list should be the operation of the inlet manifold flappy.
Without these all working properly the car will loose lots of HP.
With a completely healthy S4 a good approach in order of expense / effort is below. Changing the cams is the only open heart surgery required which could be combined with a water pump change. This first level can get you close to something like a 60 - 70 hp bump
x pipe
headers
shark tune
GT cams
Next level up before forced induction or stroker
higher lift cams than the GT cams
Inlet manifold changes
05-10-2018, 01:10 PM
#30
I bought a GT chip from JDS, john speake, and there is a noticeable difference. highly recommend; big bang for the buck.
john has a dyno sheet that shows the difference, and while not like adding a super charger, I am happy with the mod.
I first inquired about the sharktuner, but john felt, that unless I was going with other mods, (which I am not) his chip was
the way to go
he also offers an S4 specific chip.
john has a dyno sheet that shows the difference, and while not like adding a super charger, I am happy with the mod.
I first inquired about the sharktuner, but john felt, that unless I was going with other mods, (which I am not) his chip was
the way to go
he also offers an S4 specific chip.