928cs

I'm also suprised.

I will try to weight the Euro manual GTS of a friend, with standard seats, no sunroof (quite rare) and no rear AC.

worf928

I assume you are comparing the two "official" charts.

In the real world, having watched about a dozen on dynos, a stock well-running GT will put down 290 to 300. Both rwhp and ft-lbs. A stock GTS should fall into 320 to 340 on ft-lbs, but I don't recall seeing more than 300 to 305 ponies.

I think Porsche's "official" numbers for GTs were conservative and for GTSs were less so.

Note: I wrote stock. Now I'll go put on my nomex computer suit 'cause I'm sure all the x-piped, chipped, tuned, non-inertial dyno, non-corrected-numbers GTS owners are going to flame me into next week.

Nah. The rear A/C stuff is pretty light. Maybe a bit more than 12 pounds. But, I'd be surprised if it was a lot more than 20. Rear blower, evaporator, two interior hoses, a solenoid, the switch panel, and a bit of wiring. I've had most of those bits in my hand before. They aren't made of lead.

SwayBar

No flame here, just a data point.

I have a dyno chart of a Pac NW guy who's GTS with GT cams and Louie's x-pipe did 332/333 rwhp/rwt SAE on a DynoJet; strong numbers.

Interesting to note that there was no SharkTuning done after the hardware install as there was no such thing as a SharkTuner at the time, so it's reasonable to assume there's horsepower left on the table.

Alan

So how to decide - GT or GTS... GT or GTS...?

OR

Both!

Tough to find though...

Alan

Tom. M

Recently Jim Corenmans 90GT did 345ish hp and ft/lbs with just headers/louie X/louie exhaust. And a sharktune/sharkplot of course... More food for thought ..

And on the that GTS with GT cams..there was a piggy back (SMT) that was used to control the fueling at WOT...

cfc928gt

At the Dallas OCIC my '89 GT did 324 rwhp and 329 rwtq with x pipe, 300 cell metalic cats and a gts ezk chip. It also has the ford injectors but I doubt that makes any real difference.

worf928

I guess that rather than "flame" I should have written:

Now everyone with higher numbers will post theirs. But, none will be stock.

Anyone with dyno numbers (condition corrected from an inertial dyno) of a STOCK 928 (RMB can slide as it adds little or no power) that are outside of the ranges I posted? That would be interesting to me at least.

cobalt

We can't have any conversation worth noting about modified cars. Any car today can be made faster so it is always apples and oranges.

Am I reading your charts incorrectly. I was assuming these were Rear wheel numbers and I was going for a simple RPM to RPM comparison.

worf928

I agree completely. That is why all my posts use the word "stock" liberally. And my comments were based on observations of stock, as far as I know, GTs and GTSs. Although it is safe to assume that for both types many, if not all, had RMBs. I have not factored observations of the modified 928s I've seen on dynos into this part of the thread.

The single chart I posted was rwhp numbers from my '91 in bone-stock form except for an RMB. I've never been convinced that an RMB adds horsepower. But, if you want to, you can subtract one or two ponies. Depending upon the factor one uses for drive line loss that chart shows between 320-ish and 340-ish bhp. My chart is consistent with other stock GTs I've observed on the dyno.

If Porsche's official charts of crank engine power and torque (posted by Erkka) are taken as a given along with Porsche's numbers for a GT at 326/317 bhp/ft-lbs and a GTS at 345/369 then we should expect a GTS to have 15 to 19 more rwhp than a GT and 40 to 50 more ft-lbs of torque at the wheels. My dyno observations show that the former is not usually the case while the latter is closer to the truth.

Assuming that nothing was consistently wrong with all of the GTSs I observed, then a possible conclusion is that Porsche's numbers were conservative for GTs and not conservative for GTSs. Alternatively, one could conclude that all the GTSs I saw had issues with power production at higher rpms.

cobalt

For 5 speeds I usually use a 15% drive train loss which would put my car at 348 bhp and 375.5 rwtq. This is subjective but usually accepted as the norm per the experts I have spoken to. In either case using rear wheel numbers I read your chart at roughly a peak RWHP of 290 and a peak RWtq of 285 my chart is also bone stock with RMB showing 295 rwhp and 320 rwtq. This was also done at 94 degrees prior to a much needed tuneup so I can only assume the car is producing more power since the wires and plugs were shot when removed.

I can only assume that if the car was tested at a more comfortable temperature and after the tune up that the numbers would be in the range you would be expecting. Although I can't prove it until I have a chance to test it again, But my butt tells me it is stronger than before.

If anyone has any charts from a GTS they are willing to post I think it would help.

PS:

It would appear at looking at both our charts my GTS produces a very similar chart to your GT with slightly higher numbers.

danglerb

Many cars have a stock "penalty" that is easily reversed. With an 85/86 its almost pointless to compare the factory 288 hp since most cars by now have been chipped. I like to look at stock, and "simple" mods, chips and exhaust type things. Serious mods are things like forced induction, NOS, head and engine work etc.

A lot of the HP talk isn't realistic either, if a GT isn't enough hp its pretty unlikely a GTS will solve the issue.

Louie928

Dave,
You are right on with the "stock" GT/GTS comparison. GT = 290 to 300 rwhp. GTS will make about 10 rwhp less than a GT. However, the lower peak power GTS will make more torque at the 3000 tq peak. Above 4500 rpm, the GTS tq falls more quickly than a GT. I did do some work on a GTS that made more rw tq & hp than a normal GT, but those are rare.

Put GT cams in a GTS and you have a completely different animal. That combo is great, but expect to Sharktune it.

Here is a dyno chart of a stock GTS 5 spd making 286 rwhp which is about normal. The higher one, 332 rwhp, is after replacing the cams with GT cams and adding an X pipe. No tuning, but it could have used it.
https://rennlist.com/forums/attachme...1&d=1250539033

pcar928fan

Louis,

That could be MY dyno run from EITHER of my auto GTS's... That is pretty much exactly what they put down on the DynoJet rollers! Tq was 304 and 309 or something like that for the two cars. I was disappointed... RMB on one of the cars but other than that completely STOCK!

bigs

I bought a GTS for one reason and one reason only: the looks.

I just love the rear fender flares and the body-color wing.

Other than the looks, I think the choice between GT and GTS is virtually "sixes."

bronto

So, bogdan, what did you choose?