What would you put on a "highway cruiser" S4?
 

I'm trying to "step back" and figure out where I want to go with my car.

I have an 88 SE. The engine is rebuilt as of about 700 miles ago. I have a Racing Beat presilencer & cat replacement pipe, the higher performance clutch/pressure plate, and Pineapple inserts (very well secured).

My goal for my car is a nice performing highway cruiser for mid distance (300-500) mile trips. I *know* it's not the most fuel efficient, but up where I cruise (80+mph) it's actually not half bad compared to other cars.

What would be suggested for this role? I'm fixing the brakes this weekend (new pads, bleed, etc). I'm also thinking of replacing suspension parts, but I'm not sure how much of a difference it would make. I'd like to be able to take it on a track if desired, but that's not it's primary purpose.

I'm also looking for a way to get rid of the "drone" at 3000 RPM. In a range from about 2800-3200 RPM, the exhaust note gets annoyingly loud inside the car. Unfortunately, this is where I usually cruise on the highway in 5th. Would a different catback system help? Right now it has some form of aftermarket exhaust (not sure what).

-=Russ=-

your car must be geared differently than mine, because 3200RPM is like 70MPH in my car.

I have NO idea where the drone comes from, but on my '88 TII it seems to TOTALLY disappear between those revs and the car is almost completely silent...

my 10AE is primarily a highway cruiser, too, but if I was going to pick a car to do it it sure as hell wouldn't be powered by a wankel. Whats the point in having bad fuel economy when you can't have fun?

Well, either my speedo is WAY off, or it's a different rear end, because 3000 RPM is right around 80 (the speedo reads a bit high, but only 3-4mph at that speed).

The fuel economy isn't wonderful, but I've been getting 22-24mpg highway, even at high speeds. And that should go up in the near future, because I have an old O2 sensor, and the front brakes are dragging a slight bit.

-=Russ=-

hahaha, try to find some better seats, if you can.
or maybe because i'm 6'4, 240lbs i say that.

i think if you can find a way to keep it cool, that may help a lil, maybe just keep it safer. i drove my 88gxl on 400 mile trips quite often, thats was my only concern.

Lets see, within the past months I've driven my GTUs on the following road trips: 1200 miles, 520 miles (there and back) , 374 miles(both), 680(both). I've got the most horrific droning you'll ever find, and my radio doesn't work. I do manage to get 28-31mpg @ 75mph, 80 drops me to about 27.

What would you suggest for seats?

Mine runs around 1/4 to 1/3 normally, sometimes it gets up to just under 1/2. I'm planning to add some water wetter and flush the coolant system with scale remover at some point here.

-=Russ=-

What are you running? Totally stock? Or with premix, or ? Mileage numbers like that are quite respectable, no matter what you're driving. Even econoboxes don't get much higher running at those speeds.

-=Russ=-

'89 GTUs, no emissions, no cats, stock airbox, 2.5" straight exhaust. New plug wires/plugs/filters. No premix, stock OMP. I do notice that what type of gas I buy greaty affects my car too. New york gas sucks ass, it will literally drop my overall mpg down about 5. Ohio/Michigan/Pennsylvania, i've always got consistent 28-31. I generally sit around 75 and go up and down between 80 since I don't have cruise control. (try driving 19 hours straight with no cruise....)

man i get like fuckin 15 MPG, of course i also do alot of reaming.

i need to go on a long road trip and see how good of mileage i can get.

You also have a turbo that doesn't run for shit. :)

hey it runs, just only makes like 85psi of compression :)

new o2, complete tuneup, all fluide.. use redline for your tranny and diff, some castrol 20-50 gtx for your engine, get a nice cone filter, unless you already have one then get a Kn filter cleaning kit and clean yours, buy an safc and tune the fuel down (for better gas milage). this should be a good highway cruizer. oh... and a 3.90 rear end (good for high speed cruising)

New O2 sensor is sitting in the driver's side bin, I haven't had time to change it yet (got it 2 days ago). I really should change transmission fluid, I may do that tomorrow while I'm home where my jack & jackstands are. Cone filter is fairly high up on the list of upgrades, right after brakes. I'm not sure which rear end I have - any way to check? I'm turning 3000 RPM at 75-80mph, if that's useful.

How much does a SAFC run? I'm sure I could tune it leaner for highway... but I'm not sure I want to spend that much. Same with a different ignition system - I'm sure a hotter spark would help, but I'm just not sure if it's financially worth it. The rebuilt engine & exhaust & new clutch/pressure plate pretty much drained my bank accounts.

-=Russ=-

The N/A 5th gear is geared stupid low. 80 is about 3K, whereas with my TII, 3K is around 70, I think, I don't remember.

they are geared the same niggy.

No, they're not.

Looking at the FSM technical data section, 5th on the NA is 0.697:1, and 5th on the turbo is 0.762:1 - a fairly significant difference - 10% or so.

-=Russ=-

Are they different rear end ratios or something, then? I swear that they were at diff. RPM's when I was at 80.

According to the FSM again, both the turbo & NA with manuals have a 4.1 rear end, and the automatic has a 3.9 rear end.

-=Russ=-

Okay, because I was a little confused. I swore that in the N/A 80 was at 3K, and now it's higher. Thanks for clearing that up for me.

you learn somethign new every day

Might look into getting some aero pieces if you do alot of high speed driving. A stock sport package front lip and spoiler could make a noticable difference over a long stretch of road in your gas mileage. An MSD could also give you 1-2mpg aswell.

My FC did a trip from Canada to florida, to California, and then, back in Quebec(canada). Total of 1x000km !

if you turn your fuel down your leaning it out and that can blow up your motor..just a tip

My cruising is done at 3300 or so, most days (about 75 with my ratios, tires)...That would seem to be kinda high if you're thinking along the lines of piston poppers, but it's right in the "sweet spot" for a rotary...

I can duplicate SonicRat's fuel economy also, at 75 mph...Although I don't think I've ever hit 31...I consider these cars better for highway driving than city driving anyway...Plenty of "go-go" even at 75 :)

Re: What would you put on a "highway cruiser" S4?
 

I laughed my arse off when I read this, you have done a good job of reading the forum. Had your pineapple install comment not been there, a bitch session would have surly started.

For your question, need to also look at the tires. Some make a considerable amount of "road noise" at 75-80. You can also throw some sound deading material in the doors - helps a bunch. The full and complete tune as commented on below is accurate, make sure you do this including the fluids.

I have two verts and was louder than the other at 75 until I put better tires on.