4.5 VS 4.7 VS 5.0 VS S4 5.0 How much faster are these???

[PorscheFanatic]

Has anyone driven all of these motors? In real terms, how much power difference can one feel when one goes from an early 4.5 to the 1983 - 4 4.7, and then to the 5.0 etc etc?

I am curious. My 1983 4.7 was a beast - very quick. Does a 288HP 5.0 necessarily feel THAT much faster that would be worth trading up? and then to the S4?


john

[MarkRobinson]

my 4.5 is quick because the car is stripped, but a friend's euro '85 is just as fast w/o trying, faster on the very top. 85-86 tuned with exhaust 5.0s are quick because they're still marginally light for a 928.

My best 1/4 mile was a 13.5 @ 103 in a normally aspirated 86 5-speed 928, but that took a lot of practice due to the 2.20 rear end.

[MarkRobinson]

my 4.5 is quick because the car is stripped, but a friend's euro '85 is just as fast w/o trying, faster on the very top. 85-86 tuned with exhaust 5.0s are quick because they're still marginally light for a 928.

My best 1/4 mile was a 13.5 @ 103 in a normally aspirated 86 5-speed 928, but that took a lot of practice due to the 2.20 rear end.

[Rixter]

depends on what you call "fast" 1/4 mile or top speed?
the S4/GT has the advantage in top speed and overall horsepower, lower final drive at 2.20
the mid year Euro cars with 300 hp and 2.73 fd, combined with less weight, is "quicker"

[rhjames]

if you look on 928 GT's website in the tech spec's, you'll see the 0-60 times, 1/4 mile times, and top speeds for each model.

it's an easy reference to see that each year got progressively faster/quicker, even though the car got heavier and more luxurious.


--Russ

[Danglerb]

The cars got heavier, and Porsche messed around with final drive and gear ratios, but just to add a data point not mentioned, its not all about the peak HP, 32v motors (4 valves per cylinder) with the fancy tuned intake design have a 50 ft lb mid range torque advantage you can really feel in street driving.

I also prefer to look at the mildly modded performance, some models really respond to about $1000 in exhaust work and chip tuning.

Fastest are pretty clearly forced induction 32v cars, stroker motors, and maybe early (lighter) cars with Euro hybrids.

Its all out there, and generally priced accordingly. How fast can your wallet afford to go?

[DanielDudley]

The 4.7 US models have a useful increase in torque over the 4.5s. My 89 S4 five speed was a much faster car than my 80 five speed, esp at speeds over 80 MPH. However, at the stoplight, it felt sluggish off the line. My 86.5 was chipped and cat deleted. A real scalded cat, quick and fast. 85 MY absolutely have to have the exhaust replaced with a true dual setup, or they simply lose about 30 HP off the top end.

[N2O-SHARK]

Just get Euro S heads and Cams for your 4.7. Then headers and better exhuast. You'll be at 300hp in no time. You can swap them out in a weekend easy with the engine in the car. SHould be able to get a set of cams and heads for under $1500 tops.

MY daughter's 4.5 Euro (Non S) now has Euro S heads and cams with MSDS headers, X pipe and dual 2.5" exhaust. It's putting down 257HP at the rear wheels. That's a tad more than a stock 300hp Euro S does. Her '81 is lighter than any stock 85-86 and will easily take it off the line with her 5 speed and better gears. I have also found the Euro 4.5 with it's higher compression seems to have more mid range torque than the US 4.5

If you know your car, I'd upgrade before I by another shark that may have issues. If you're real hungry for power, build a hybrid with a 5.0L bottom and Euro S top end goodies. A Hybrid with headers, X, and upgraded exhuast combined with less weight and better rear gears should easily keep up with a GTS.

[Danglerb]

The X pipe and dumping the factory cats for something modern or nothing at all give a BIG kick, same for improving the exhaust manifolds.

Don't forget the Euro intake, the US version is something like half the flow with that tiny throttle, that said at lower flow rates most of these "variations" behave very much the same up to about 3000 rpm.

Well done I think a 5.0L hybrid can put down a true 300 to 310 rwhp, the high side dependent on some port work on the heads. Unfortunately this is just about where the fun begins, leaving few inexpensive options for a bit more power. Thats what makes a 5.4L so tempting, plus increasing the bore, unlike stroke, doesn't have rpm issues (pistons only like so many feet per second or some such).

[785sp]

Thank you for asking what I've been afraid to.

Asked another way, once you're up to highway speeds, mashing the pedal in 4th up to about 90 mph, and then mashing it again in 5th up to 120 or so, how do the models really compare?

(In my book going faster than 120 on any public highway is suicidal, but to each his own.)

[N2O-SHARK]

At 90mph on the highway, you don't mash it in fourth, you down shift to 3rd, stomp it and ride it out. That's where the Euro's 300hp will really shine. Not so much off the line.
At 60mph in third you're just coming into the power band in all 3 engines.

[Danglerb]

Originally Posted by 785sp

Thank you for asking what I've been afraid to.

Asked another way, once you're up to highway speeds, mashing the pedal in 4th up to about 90 mph, and then mashing it again in 5th up to 120 or so, how do the models really compare?

(In my book going faster than 120 on any public highway is suicidal, but to each his own.)

Thats going to be a whole lot about the gears in the car and the exact speed you mash at. Even my old 81 3 spd auto would do the 60 to 90 passing thing in a very frisky manner. Over 80 mph or so I suspect the GT and GTS have a real edge, but an OB with a hybrid is going to pull really hard too. I think Mark A said his old Euro motored car would do 175 mph, but really, nobody seems to complain about top end with a 928, just off the line and around the city grunt.

BTW on my 5 spd I think I am still in 3rd around 90 mph, and not shifting to 5th until about 120 mph. I'll have to go test that asap.