Getting more HP from an 87 Porsche Carrera

[Lake Guy]

Not sure if we're talking engine rebuild or tires with this thread but I'm in the middle of a 3.2 rebuild project. My guy tells me the engine is pretty tired so I'm in for a full rebuild and upgrade. Would love to have some ideas on what I've got planned:

new pistons to get to 3.4
reground cams to 964 spec
SSI and sport muffler

Any other suggestions that I should be speaking to my mechanic about?

Mark.

[needspeed]

Originally Posted by Lake Guy

Not sure if we're talking engine rebuild or tires with this thread but I'm in the middle of a 3.2 rebuild project. My guy tells me the engine is pretty tired so I'm in for a full rebuild and upgrade. Would love to have some ideas on what I've got planned:

new pistons to get to 3.4
reground cams to 964 spec
SSI and sport muffler

Any other suggestions that I should be speaking to my mechanic about?

Mark.

Going through the same process myself. I'm in CA and need to keep the CAT, so I'm sticking with stock heat exchangers. However, I'm looking into the Fabspeed sport CAT and M&K light weight muffler.

Definitely going down the 964 cam route. Plus the Patrick Motorsport RSR style rocker and sport spring set. Plus ARP connecting rod bolts and head stud kit. Plus light weight clutch housing to reduce rotational weight. Plus new Bosh injectors for better combustion. And Plus chip (maybe club sport).

I'm hoping this will allow the car to rev quickly and comfortably to 7k RPM then sustain it. I like cars that rev for primarily the street and occasional track duty.

I'm still debating whether it's worthwhile going to 3.4. To get full benefits, many claim it also requires twin plugging. The cost for material and labor for 13ish HP gain is extremely high.

[sp_cs]

You guys can buy max moritz pistons designed to avoid need to twin plug, I believe.

To the above I’d add a KEP HD Lite ally clutch housing, for some weight loss and added ‘zing’.

[Cevan]

Originally Posted by Lake Guy

Not sure if we're talking engine rebuild or tires with this thread but I'm in the middle of a 3.2 rebuild project. My guy tells me the engine is pretty tired so I'm in for a full rebuild and upgrade. Would love to have some ideas on what I've got planned:

new pistons to get to 3.4
reground cams to 964 spec
SSI and sport muffler

Any other suggestions that I should be speaking to my mechanic about?

Mark.

SSI are not a performance upgrade for a 3.2 b/c you're gonna go from a bigger exhaust port to a smaller primary.

[Raceboy]

Worth noting that with VEMS you can easily upgrade to twin plug ignition. Cheapest route is using two 6cylinder coilpacks, more expensive ways are 12x COP or twin plug dizzy with two coils that are directly fed from VEMS (that is the way I went with my 2.4S twin plug engine.

[cabmandone]

Originally Posted by AHudson

I did this exact thing to my 85 Carrera, couldn't be more pleased.

1. Euro Pre Muffler
2. 84 mm Dansk Sport Exhaust
3. Open air box
4. Sal Carcellers 4 hole injectors
5. Sal's matching chip

In total, starting, idling way smoother, more refined and modern feeling. Pulls far harder than before, nice but not too loud on the exhaust note. To me it's a different, more driveable, more fun car.

4&5.
Sal is a great resource. The beauty of what he does is he won't sell you something until you've sorted the engine out to be sure it's running properly stock. Once both of you are satisfied it's running properly, Sal will make recommendations based on your budget and his experience. Sal strongly recommends an AFR gauge with wideband 02 sensor and I understand why he does. I run a custom tune by Sal with a very free flowing exhaust and I'm happy with the overall driveability of the car. As I understand it if you really want to go wild you can have the intakes port and polished, have the throttle body bored, add Sal's Maf/Injector/Tune ( he requires you to send him your ECU for inspection and installation of the chip) and really wake the car up. Once all is installed you use software to log data (afr's) and he can tweak the system to get the most out of it.
I'm not advertising for Sal, I'm merely a very happy customer and I know there are others here as well.

If you don't want to go that route I'd probably go the route my brother went and move the torque into the lower RPM range. AFAIK our engines don't have a lot of HP difference but driving his where the torque comes in around 3K or so is a world of difference from driving my car. His is a neck snapper where mine is just "fun"

[SteveDraz]

I've got an '86 that makes about 252 hp. PO did most of the work.....
1. Webcam 20/21 cams
2. Twin-plugged (doesn't really do much - stock P & C). One day I'll get some higher compression pistons.
3. SSI heat exchangers. Standard 2-in 1-out muffler. Obviously no cat.
4. Ring & pinion 7:31.
5. Steve Wong chip.
6. Aluminum pressure plate.
7. Opened air-box (fabspeed - flimsy, but it hasn't cracked or fallen off)

Gearing is a bit short but it's still fun. Take it to the track all the time.

[WP0ZZZ]

Originally Posted by Bill Verburg

Here's the actual chart, I did mention that the shorter tire would raise rpm at any speed and entail more frequent shifting, You never get something for no cost

Bill thanks very much for those awesome plots! The comparison of tyre diameter with weight reduction was particularly illuminating.

If we look at the plot I'm quoting above 80 mph, assuming optimal gear selection for max thrust, it is clear that in some speed ranges the larger diameter tyre has more thrust and in some other ranges the smaller diameter tyre has more thrust. Do you have any comment on that?

[jons911]

2Cam,
I'm planning a twin turbo EFI build on my 3.2 down the line. I was hoping to get started this summer, but it looks like it will get pushed at least until next January or so. However, I've done quite a bit of work to figure out various components and sources for such a swap. If you're interested I'd be more than happy to give a much more detailed layout of parts/kits and sources/prices.

[Driven97]

Originally Posted by WP0ZZZ

Bill thanks very much for those awesome plots! The comparison of tyre diameter with weight reduction was particularly illuminating.

If we look at the plot I'm quoting above 80 mph, assuming optimal gear selection for max thrust, it is clear that in some speed ranges the larger diameter tyre has more thrust and in some other ranges the smaller diameter tyre has more thrust. Do you have any comment on that?

Yeah changing gearing isn't magic, it just shifts (pun!) stuff around.

Pulling hard through 3rd at 80 on the small tires the car is about to run out of gear and needs an upshift to 4th. On the larger tires there's still ~1,000rpm left to play with in 3rd. But note by 90mph the smaller tire crosses over to pulling harder in 4th as the larger tire car reaches redline in 3rd, then holds an advantage to about 105. They swap again at 115 and then a final time at 130.

An important thing to note is that gear changes take time (especially for us 915 guys) so while lowering the effective ratio looks appealing, in the real world it can end up slower, situation dependent. For example, if you geared a 911 to reach 60mph at the top of 5th the thrust chart would look insane. However, you'd need 4 shifts to get there, and gears 1-3 would be pretty useless.

[Bill Verburg]

Originally Posted by Driven97

Yeah changing gearing isn't magic, it just shifts (pun!) stuff around.

Pulling hard through 3rd at 80 on the small tires the car is about to run out of gear and needs an upshift to 4th. On the larger tires there's still ~1,000rpm left to play with in 3rd. But note by 90mph the smaller tire crosses over to pulling harder in 4th as the larger tire car reaches redline in 3rd, then holds an advantage to about 105. They swap again at 115 and then a final time at 130.

An important thing to note is that gear changes take time (especially for us 915 guys) so while lowering the effective ratio looks appealing, in the real world it can end up slower, situation dependent. For example, if you geared a 911 to reach 60mph at the top of 5th the thrust chart would look insane. However, you'd need 4 shifts to get there, and gears 1-3 would be pretty useless.

Changing the gear, changing the gear ratio or changing the drive tire OD all affect the thrust curve

A good example is seen in this comparison of 2 993 transmissions, the /20 is a stock street trans and the /30 is the stock racing trans in a Cup or RSR

All the gears in the /30 except first and second are shorter and all are closer together to minimize engine rpm drop w/ shifts, 1st is easy to see the taller 1st in the /30(blue) reduces thrust at all points and moves the peak torque to the right or higher speed, in 1st the /20 car w/ the same engine would beat the /30 car to 31mph, but maybe not to 37 because a shift would have to occur which would slow the average rate of acceleration. You'd need to time the cars to actually see. The same occurs in 2nd but to a lesser degree because the difference in gearing is less. For the rest of the gears the opposite occurs, the shorter /30 gears move thrust peak to the left but again to a lessor extent because the difference in gear ratios is less. But in every case the trans w/ the shorter gearing will out accelerate the taller for most of the time spent in one of the shorter gears, Additionally if the curves for a given transmission cross, that is an indication that a short shift is called for, because the higher gear now provides more thrust than the lower gear.

[Techno Duck]

Originally Posted by needspeed

Going through the same process myself. I'm in CA and need to keep the CAT, so I'm sticking with stock heat exchangers. However, I'm looking into the Fabspeed sport CAT and M&K light weight muffler.

Definitely going down the 964 cam route. Plus the Patrick Motorsport RSR style rocker and sport spring set. Plus ARP connecting rod bolts and head stud kit. Plus light weight clutch housing to reduce rotational weight. Plus new Bosh injectors for better combustion. And Plus chip (maybe club sport).

I'm hoping this will allow the car to rev quickly and comfortably to 7k RPM then sustain it. I like cars that rev for primarily the street and occasional track duty.

I'm still debating whether it's worthwhile going to 3.4. To get full benefits, many claim it also requires twin plugging. The cost for material and labor for 13ish HP gain is extremely high.

My engine is very similar to what you listed, i went single plug 3.4L, 9.6:1 c/r, 964 cams, titanium retainers and springs and a few different exhaust setups over time. Also a KEP lightweight pressure plate. With M&K muffler and a euro pre-muffler my car made 242whp / 225ft-lbs on a Dyno Dynamics; this dyno based on other friends cars is optimistic..i think i am realistically around 230whp. A well setup 3.2L is probably around 210-215whp. The 15bhp difference is marginal but i find the 3.4L has better low and mid range torque...maybe this is attributed to the 964 cams though. Twin plug is where you really can take advantage of the 3.4L but unfortunately i have to deal with smog and 91oct so the 9.6:1 c/r was a necessary compromise. Whether i would do it this way again is debatable, but i needed new pistons and cylinders regardless; labor was actually no different. So it was just the cost difference between 3.2 and 3.4 p&c's.

If i were to do it again, i would go twin plug 3.4L which would allow higher compression. Cost really goes up when you twin plug though... extra machining to the heads, twin plug distributor and tuning.

Shameless plug, i have a Monty muffler for sale if interested .

[WP0ZZZ]

Originally Posted by Bill Verburg

All the gears in the /30 except first and second are shorter and all are closer together to minimize engine rpm drop w/ shifts

When gears are closer together it is very clear to me that greater acceleration can be achieved. Since rpm drops are smaller, the engine can be kept at high rpm where more power is produced and, as a consequence, more energy from the engine can be converted to kinetic energy, i.e. speed.

What I'm trying to wrap my head around is the plot you shared earlier where a change in OD of the tyres means that all ratios are shorter but not closer together: rpm drops between neighbouring ratios remain the same. I have coloured the plot you shared earlier to highlight how the larger diameter tyres (yellow) result in greater thrust at some speeds while the smaller diameter tyres (blue) have more thrust at other speeds.

[Bill Verburg]

Originally Posted by WP0ZZZ

When gears are closer together it is very clear to me that greater acceleration can be achieved. Since rpm drops are smaller, the engine can be kept at high rpm where more power is produced and, as a consequence, more energy from the engine can be converted to kinetic energy, i.e. speed.

What I'm trying to wrap my head around is the plot you shared earlier where a change in OD of the tyres means that all ratios are shorter but not closer together: rpm drops between neighbouring ratios remain the same. I have coloured the plot you shared earlier to highlight how the larger diameter tyres (yellow) result in greater thrust at some speeds while the smaller diameter tyres (blue) have more thrust at other speeds.

That's correct, a change of cwp or tire OD is universal, ie applies at all speeds and engine rpm, so the net thrust is raised or lowered but the spread is not, The only thing that widens or closes the gaps between gears is a local change, ie change of individual gear ratios.

I like the fill, It never occured to me to show that, that area under the curve represents the net gain in performance in a specific gear, the sum of the areas is the net gain overall

[scarceller]

+1 one this response!
Exhaust can really get you a lot of bang for the $$.
A good set of 1 5/8" headers but not just any header, the length of the primaries really matters in the 3.2L. You can't move the peak torque RPM much, it tends to be around 5800RPMs and the header length must match this RPM. Hint: do NOT use short headers! The optimal header primary length works out to be about 28"-32" for the 5800RPM point. Trouble is it's hard to find long headers like this.

Originally Posted by Quicksilver

The power you get from a chip is going to be from reducing the safety margins that the manufacture built in to deal with bad gas or from the "tune" of the engine deteriorating. The Steve Wong chip tells you their expected octane and you will need to use it. A chip isn't going to get you any serious increase in power. Much of the increase would be in driveability (Oh, and a lot of the chips are crap and don't help a thing.)
I take my car to Mexico every year so a safety margin for gas is just good sense and an aftermarket chip is out. I upgraded my car with the last chip that Porsche made for the 3.2s: #1267355358. It is the same as the ClubSport chip without raising the redline.

I had a discussion with Jerry Woods and Bruce Anderson about what you can do with the 3.2 and their answer was very clear. "There is 20 HP in the exhaust. Porsche didn't leave any power on the table in the intake or anywhere else." In other words a good set of 1-5/8" headers/heat exchangers will make you some power. Plus you can have fun selecting a muffler that will make you smile.

If you want more from the engine you will have to make changes so it pumps more air through it. That means: Turbocharge, supercharge, spin it faster, and/or increase displacement.
All of those means you either open up the motor and make changes or replace the motor.

[scarceller]

Here's an example 3.2L rebuild, nothing wild here. Pay close attention to the exhaust setup.
http://forums.pelicanparts.com/porsche-911-technical-forum/915427-84-89-911-exhaust-proven-results.html

[darrin]

Originally Posted by scarceller

Here's an example 3.2L rebuild, nothing wild here. Pay close attention to the exhaust setup.
http://forums.pelicanparts.com/porsche-911-technical-forum/915427-84-89-911-exhaust-proven-results.html

Sal -- interesting, so this rebuild used stock headers/HE with the custom muffler? For us folks that need to remain emission legal, wonder how close one could get to this performance while still retaining a cat.

[douglas bray]

Originally Posted by stlrj

I'm still on the stock chip but went to the GM multec 5 hole injectors on my 87 Carrera and also have a beast of an engine. What a joy just driving around town!


Cheers,

Joe
87 Carrera

Yep, but nobody wants to talk about it 'cause it's a race shop secret so we leave it alone.

[needspeed]

Originally Posted by douglas bray

Yep, but nobody wants to talk about it 'cause it's a race shop secret so we leave it alone.

Seems like better air-fuel mixture should also reduce detonation. Win all around.

[douglas bray]

Originally Posted by needspeed

Seems like better air-fuel mixture should also reduce detonation. Win all around.

Runs cooler too. Win/win/win