Baseline Dyno 3.2SS
 

Here are my baseline numbers on my 3.2SS single plug, CIS, 964 cams, 98 mm J & E pistons and 95 mm Mahle cylinders bored to 98 mm, 9.5:1 CR, MSD ignition, motor built from a '79 SC. Limter set to 7500 rpm.

http://forums.pelicanparts.com/uploa...1593187593.jpg

https://www.youtube.com/watch?v=iaPqLFX_jRs

Seems low, but you are pretty lean at 6500+. There’s more power to be had once the a/f is corrected.

Does seem low. I got the same power (a little more, but within the margin of error) on my old SC with 964 cams, 9.5:1 pistons, and early exhaust. CIS, stock displacement. Your AFR's aren't terrible, but they're never really in the sweet spot. They slowly climb from too rich to too lean.

Holy lean afr batman!!

That needs resolving ASAP IMHO....

Now you can work on the tuning. I think you have some more HP potential.

What exhaust and muffler? Heck the right muffler can be 5 - 10 hp. What about the distributor and timing? Air cleaner? And yea the AFM.

There was a thread a while back where someone played with his cam timing on an SC motor and got some gains. Maybe someone can find that link?

Thanks, guys. Yup, next is adjusting the mixture to get the AFR better. Exhaust is SSI in to M&K sports muffler 2 in 1 out and K&N oiled air filter on a stock snorkel airbox with a few additional holes drilled in. Stock single plug distributer. What should I see when all things get corrected?

On a couple motors here, we found the M&K to be restrictive. Do another run without the muffler to see if this is a potential source of restriction.

http://forums.pelicanparts.com/porsche-911-technical-forum/1018103-muffler-dynomax-magnaflow-m-k-dyno-charts.html

Consider starting the dyno run at 2000 rpm so you can tell more about cam behavior.

Sent from my Nokia 7.1 using Tapatalk

Have you verified that you're getting full throttle opening when the gas pedal is floored? On old cars, especially ones that have been worked on, it's very common that the linkages need adjustment.

I haven't verified the throttle is opening completely. I will check on it.

Lean from 5500 I would say. But it is cis so it might be hard to correct.

Contemplating Franken CIS or modified WUR/FD. Anyone have any experience with that. Seeing what can be done reasonably before going to ITB/EFI.

I looked at Franken CIS before, but I think its a kludge. Would consider it if I wanted to retain the stock/original look on special car.
If not going ITB, I would buy the specific bits from the bitzracing and combine it with a proper EFI system.

If going ITB, I would go with AT Power ITBs. They are killer on 3.2 engine. They make big power and have incredible throttle response. I am using those on my hyper 3.6L engine along with a MoTec M130 ECU but they work great with any quality ECU.

Okay hope you don't mind looking at this and I'm not trying to hijack.... thought it would be interesting to see a similar Build 3.2 SS ('83 case) w/ Mahle Pistons & Cylinders 10.0:1(actual 9.8:1) Compression measured, 964 cams, MSD Ignition, 46 PMO's and SSI with 3" custom exhaust from Turbo Hoses. Single plug, 98 octane 6800 RPM's test in 3rd gear. 4th gear test HP 182 & Torque 193http://forums.pelicanparts.com/uploa...1594942704.jpg

CBA, so you know Hoover. My car was Dynoed at his shop. Correct me if I’m wrong but it appears either my CIS is doing prettty good or your ITB setup needs more tuning? Some say there is like another 30-40 hp to be had going from CIS to ITB/EFI on these 3.2SS? I need to go back and see if there is anything I can do to riches the Mixture on the CIS. I already gave a quarter turn clockwise on the fuel distribution block and I noticed the idle was smoother.

Maybe you're both being held back by SSIs.

Sent from my Nokia 7.1 using Tapatalk

Interesting... I'm no expert at all......so anything I say can and will not be held against me :) I've been told by that CIS and Carbs maybe you can get 15 HP...maybe... but at the end of the day CIS can be tuned pretty darn close to carbs. Carbs are more of the fun factor, sounds a little cooler, looks cooler and maybe a little more responsive. My car was tuned without a dyno and I don't know what the timing was set at... maybe this could make a difference? Yes I know Hoover and would love to go up there and have him tune my car on his dyno just a little bit of a hike for me. The dyno guy I used said my fuel mixture looks really good across the board but their are different adjustments that could be made. My motor has about 2,000 miles on it and I really haven't tried to dial it in but I'm not sure how much more can be made. I consulted with Steve W. when I built this motor with the goal of having something reliable, single plug, and fun and he felt that 215 to 220 HP(crank) would be what I'd get out of it which seems pretty accurate based on these numbers at the wheels. I've also consulted with a handful of other builders who agreed with Steve's #' but also said if I went with more aggressive cams, timing, and dual plug I could see 230-240 HP. Not sure what your goal was when you built yours.

I'd be interested in hearing from some "experts" on the horsepower / torque numbers on how mine looks. My buddy is doing some testing for some new headers. I can't share the company yet but will when given permission. His 1973 911 w/ a 1989 3.2 Stock motor with CIS yesterday w/ custom 1 5/8" ID 13/4" OD headers, 2 in 2 out exhaust and his HP was 192 and torque was @ 172. We meet up today to dyno his car again He had same headers w/ Megaphones and his HP went to 198 w/ Torque @ 178. Tomorrow he is doing European style headers w/ 2 in 2 out exhaust. He will do a 4th test with Stock SSI's and 2 in & 2 out exhaust.

Fun Stuff. All in all I'm happy with what I have... I think :)

CBA,
Your numbers indicate problems. You need some tuning or different parts. Your power falls off bad above 5K RPM.
I posted several dyno runs of well tuned stock 3.0, SSI (or headers) with stock cams and CIS in the thread below.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/1064529-air-fuel-ratio.html

I also show how bad a muffler can be even if you can see straight thru it.

The dyno below shows 3 runs on same day same care with megaphones vs early muffler (loelles) converted to sport (straight pipes out rear, loud) vs early with second outlet on end (davids) . You can see the numbers are about the same but slight change to shape. I tried a lot of mufflers (most sucked) on a stock car and early muffler with second outlet is hard to beat for power.


http://forums.pelicanparts.com/uploa...1595022115.jpg

john

Thanks John for sharing. Really appreciate and will look into it more. Always learning here.

CBA you really are down on power. Years ago I had an SC and did a build with 964 cams, 9.5:1 compression pistons, SSI's and early muffler. Stock displacement, stock CIS. Put down an honest 200 at the wheels. You should be doing better than that with more compression, more displacement, and carbs.

CBA, why did you use 964 cams with those pistons? Are those the CIS style pistons or the carb/EFI pistons?

You may have too high of dynamic compression with that little overlap.

Bingo. CIS Pistons w/ single plug, heads ported to 38mm, 964 cams, MSD, SSI headers, 3” exhaust( think this is too big) but it sounds so nice. Do you think headers and exhaust could change things up?

Carb/ EFI compression pistons was too high at 10:2 For single plug I was instructed .

CBA, If you compare the dynos I posted with yours which were all done on the same type of dyno (dyno Jet) you are down on power. If we take the 187HP made with a 3.0 and extrapolate to a 3.2 you would have 198HP. This is with stock CIS and Stock cams. Considering that most 3.2 Carrera motors (which are smaller then your 3.2) on a dynojet make in the area of 220-230HP with stock cams and 230+ with 964 cams you are missing a lot of power. Some dyno examples below

https://www.911chips.com/dyno.html

I would think with carbs and your setup you should be in the 230-240HP at the wheels with a HP peak at 6300-6400 RPM.

You will have to do some investigation to figure out where you are loosing power. Muffler, cam timing, A/F ration and ignition timing is where I would look.

john

If you look at the torque curve you will see that the carbs are making nearly 20 ft lbs more torque across most of the mid-range power band compared to your CIS. Agree that the peak numbers are nearly the same but I can guarantee that the carbs will feel much stronger accelerating.

Yes, Peak power rpm and torque drop off are steeper than I would expect on both posted graphs.

Franken CIS on 3.3SS
 

Franken CIS or maybe even worse! When I built a 3.3SS for my SC, I decided to keep the CIS system but modify the stew out of it! What I wound up with is an early large port air box, hardware from a 1980 system and a reconfigure to be more like the 73 1/2 system. I also did a little trick with the cold start valve. I added a push button switch and wiring so that the CS valve would be opened at wide open throttle. It is also wired to activate when starting a cold engine. I also added an A/F gauge to help with tuning. End result (after lots of tuning time!) is a system that pulls like stink all the way up to 7500 rpms where it hits the ignition interrupt. You probably need to know some more about the engine so here tis: 11:1 Mahle low dome pistons, LN Engineering slip fit cylinders, 964 cams, Carrera twin plug heads, matched ports at the head/intake runner and at the head exhaust and the SSI tubes. I had to open up the ends of the intake runners about 3mm to match the head intakes and I had to flare out the SSI exhaust tubes about the same amount to match the cylinder head exhaust ports. Compression on all cylinders runs either 160 or 161. With the 7th injector (CS Valve) the A/F ratio improves from about 14.5 to about 13.0. The airbox has the little aluminum "spider" that helps to direct fuel to all cylinders. Ignition is handled by an XDi crank fired/twin plug system. I have the initial timing set at 8 degrees and the all in advance is 28 degrees. Being able to set the timing at a lower value reduces the negative work done by the piston, helps the engine to run cooler and allows the engine to run safely on 91 octane pump gas. Here is a picture of the Cold Start Valve actuation switch. I hope this will give you some ideas for your induction system. Don't be afraid to jump in and try some things!

http://forums.pelicanparts.com/uploa...1596674484.jpg