82 911SC, how much HP? I know I know

[Geronimo]

IIRC these were 180CHP when knew, I as I drive about I can't help wondering what my car makes in its current form and 110K on the clock.

82 SC with SSI, M&K 2 into 1, PMO 46mm carbs, MSD ignition, recurved Dist...

I figure it might be back to 180CHP after years of use.

[Adrock]

Easy way to find out... dyno.

[Geronimo]

Yea, I don't care that much... i'll worry about that when it's new motor time.

[30westrob]

I would suspect you are well above 180. A 110K well maintained engine with a small loss for wear and a much larger gain for your upgrades.
Rob

[Superman]

As much as guys imagine that the larger intake runners allow the early SCs to breathe better, I do not agree. I put "20/21" cams in my '83 engine combined with SSI exhaust and the dyno says 186 hp ( and 186 lb/ft of torque) at the rear wheels. That means 205 hp. The higher compression pistons combine with the smaller intake runners (which help 'pack' the combustion chamber using higher velocity intake air) to make more power. Heck....my hp numbers would be higher if I had stayed with the stock cams. The 20/21 cams simply widen the power band.

[Tippy]

Originally Posted by Superman

As much as guys imagine that the larger intake runners allow the early SCs to breathe better, I do not agree. I put "20/21" cams in my '83 engine combined with SSI exhaust and the dyno says 186 hp ( and 186 lb/ft of torque) at the rear wheels. That means 205 hp. The higher compression pistons combine with the smaller intake runners (which help 'pack' the combustion chamber using higher velocity intake air) to make more power. Heck....my hp numbers would be higher if I had stayed with the stock cams. The 20/21 cams simply widen the power band.

I don't have any real numbers comparos, but that simply does not make sense. Higher velocity is for low RPM torque, not higher WOT. Believe you witnessed a poorly tuned car is all.

Get the AFR's and BMEP timing correct, and the larger port motor should win every time.

[flat6pilot]

Here's a yardstick dyno run.

1980 "euro spec" SC, ~180,000 miles, Megasquirt EFI, Georges headers, M&K 2 in 2 out muff. No internal mods.

I dyno'ed at 187whp. I believe that year SC is spec'd as: 188HP (flywheel HP)

[emcon5]

Originally Posted by Superman

As much as guys imagine that the larger intake runners allow the early SCs to breathe better, I do not agree. I put "20/21" cams in my '83 engine combined with SSI exhaust and the dyno says 186 hp ( and 186 lb/ft of torque) at the rear wheels. That means 205 hp. The higher compression pistons combine with the smaller intake runners (which help 'pack' the combustion chamber using higher velocity intake air) to make more power. Heck....my hp numbers would be higher if I had stayed with the stock cams. The 20/21 cams simply widen the power band.

Everything I have read about the port size change said the reason was to boost low-end torque. The smaller ports and runners force the air to move faster, which increases torque. The problem comes higher in the RPM range, where the peak torque drops off earlier and faster as the small ports start to restrict total air flow.

Fourteen years ago I graphed torque curves for a few different engine configurations, and two that really stood out were the dyno sheets from Dane (rdane) and Jim (Superman). Here are the torque curves:



Jim has an 83, Dane a 79. Both engines have early exhausts with Web 20/21 cams, and CIS, and these were done on the same dyno, on the same day. Dane has lower compression, but larger ports. It looks like the smaller ports and compression gave Jim a boost in torque down low, but as the RPMs climb, the Torque drops off earlier (5000 rpm vs 5600) and faster than Dane's. Jim drops 20% between 5K and 6.4K, Dane only drops 13% and most of that is >5.6K.

My engine is a 3.2 Short stroke with 9.8:1, twin plug, 964 Cams and SSIs, and it starts to drop off about the same point as Jim's engine, but drops a lot faster, ~25% between 5K and 6.4K. My belief is because the intake ports are undersized, additionally, the primaries of SSIs are a little small for a 3.2.

On the other hand, my engine has a ton of torque. Consider that a factory 3.2 had 192 lb. ft. at the crank, and my engine (if you believe the numbers) has ~186 at the tires.

[GothingNC]

I would say you are close to 205 at the flywheel

Here is mine at the wheels from the prior owner, there was an issue getting a good RPM through the Magnacore wires causing a "quirk" at the end.

3.0
CIS-enlarged intake runners
9.7 Compression
Elgin SC330 Cams
SSI's with Dansk Sport Exhaust

[Coastr]

On my reading of the period literature, the changes of small ports and huge compression were to meet emissions and make it more tractable for the us market (ie more small-block like in delivery). Or maybe it was just moving engine efficiency around to match where the epa tests were done. IIRC the ignition timing is different as well.

Discussing torque gets messy quickly but what we often say as ‘higher torque’ motor really means ‘earlier torque peak’

[QueWhy]

Originally Posted by Tippy

I don't have any real numbers comparos, but that simply does not make sense. Higher velocity is for low RPM torque, not higher WOT. Believe you witnessed a poorly tuned car is all.

Get the AFR's and BMEP timing correct, and the larger port motor should win every time.

I don't know where to find the post but Steve from Rennsport in PDX said basically the same thing as superman. Velocity is more important than port size.

[Josh D]

I'm not buying the "small port is better" argument either. When Porsche finally increased the compression on the 3.0 to 9.8:1, they got 204 HP and 198 ft/lbs. (930/10). It's a big port motor.

When they came out with the 3.2, they increased port size again and made 231 HP (Euro spec). And that is with the same cams as the 3.0.

The small port and runners was an exercise in lower rpm tractability, efficiency and emissions. Remember, speed limit was 55.

['76 911S 3.0]

Originally Posted by emcon5

Everything I have read about the port size change said the reason was to boost low-end torque. The smaller ports and runners force the air to move faster, which increases torque. The problem comes higher in the RPM range, where the peak torque drops off earlier and faster as the small ports start to restrict total air flow.

My engine is a 3.2 Short stroke with 9.8:1, twin plug, 964 Cams and SSIs, and it starts to drop off about the same point as Jim's engine, but drops a lot faster, ~25% between 5K and 6.4K. My belief is because the intake ports are undersized, additionally, the primaries of SSIs are a little small for a 3.2.

On the other hand, my engine has a ton of torque. Consider that a factory 3.2 had 192 lb. ft. at the crank, and my engine (if you believe the numbers) has ~186 at the tires.

Essentially same engine as you, 3.2SS with 9.5:1, single plug, 964 Cams and B&B Headers and Muffler, BUT with big port heads, 4R CIS (big port).

This was on a Mustang Dyno, 204 WTQ and 194 WHP (RPM trace was not calibrated quite right, redline was closer to 6500):

[Geronimo]

195WHP from a 3.2ss.... dear lord thats depressing (considering the cost) I was planning a 3.2ss build when my motor is no longer meant for this world.

I have to remember I didn't buy this car to have a fast car, but a fun car.

[Josh D]

Originally Posted by Geronimo

195WHP from a 3.2ss.... dear lord thats depressing (considering the cost) I was planning a 3.2ss build when my motor is no longer meant for this world.

I have to remember I didn't buy this car to have a fast car, but a fun car.

So that's about 225 FW HP. That's a 45 hp, or 25% increase over 180 hp. I'd say that is pretty darn good! A 25% increase in power + a couple hundred lbs shed from the car and it will be fast and fun!

[Geronimo]

Yea, i'm sure it performs well. I'm just adjusting from American $ per HP where 5K gets you 500HP.

I would think a well build 3.2ss would be closer to 245-250CHP range... but I am sure there are so many variations on builds.


Make my Porsche light, build Cobra kit for those brutish days.

[Geronimo]

3.0 to 3.2ss with pics and Dyno sheets before and after


Saw this 3.2ss build and thought 253RWHP would make for one very fun lil car... I don't know enough to hone in on the differences between the builds.

If I can get to the 250RWHP make I think I would be a very happy boy.

[Josh D]

Originally Posted by Geronimo

Yea, i'm sure it performs well. I'm just adjusting from American $ per HP where 5K gets you 500HP.

I would think a well build 3.2ss would be closer to 245-250CHP range... but I am sure there are so many variations on builds.


Make my Porsche light, build Cobra kit for those brutish days.

His number was with CIS and a CIS friendly cam. You have PMO's already and could get to 250 with the right pistons and cam.

[emcon5]

Originally Posted by Josh D

His number was with CIS and a CIS friendly cam. You have PMO's already and could get to 250 with the right pistons and cam.

From Bruce Anderson's 911 Performance Handbook, submitted without comment.

['76 911S 3.0]

Originally Posted by Geronimo

195WHP from a 3.2ss.... dear lord thats depressing (considering the cost) I was planning a 3.2ss build when my motor is no longer meant for this world.

I have to remember I didn't buy this car to have a fast car, but a fun car.

Remember that's on a Mustang dyno, a DynoJet would be about 15% greater or about 220WHP.