John, did you see mine?
http://forums.pelicanparts.com/porsche-911-technical-forum/158331-dyno-results.html

Short stroke 3.2, 964 cams (reground by you) twin plug, 9.8:1, SSI, stock small late SC ports. Lots of torque, but it drops off quick. I think my small ports are kicking my ass.


Here is Dane's dyno sheet:


http://standingwave.org/albums/porsche/amp.sized.jpg

Tom

Tom, The link points to a silver 912?
Is this the graph for Danes 79 SC ?

John, the 219hp dyno Tom posted is my 3.4 built on my original 3.0, same set up as below. Thanks Tom:)

Here is my original 3.0 '79 CIS with SSIs, a 2/2 Dansk and a 20/21 web cam.

http://www.standingwave.org/albums/p.../agg.sized.jpg

I guess the HP and torque don't drop off as quickly as I first had stated...still loosing 2/300 rpm on the top end though.

Here is Tom's 3.2 CIS. Any idea what happened here?

http://forums.pelicanparts.com/uploa...1081901228.jpg

98MM Mahle Cylinders with RSR Pistons, measured at 9.8:1 CR.
Cam reground to 964 profile by Elgin.
Twin plug with Rennsport 964 distributor conversion, 2 Bosch CDIs and coils.
ARP rod bolts, 993 steel head studs.
SSIs with a Dansk muffler.
Stock CIS system.

Tom,
Where did you dyno your car?

Dane: Your smog is a LOT more tame than the CA smog, at least the stage 2 on the dyno. Tom already posted the limits. I just verified them. They are the same for my 81.

Here compared the CA 15/25 mph limits with the WA idle / cruise limits. Even if we set your 4000 rpm cruise equal to the CA 25mph/2500rpm, you would have failed miserably. :(

Also, no NO limit in WA? Well then you can lean the living daylight out of your setup and pass.

HC
limit CA 141/114
limit WA 600/240

CO
limit CA 0.99/0.79
limit WA 2.6/3

NO
limit CA 1148/978

I just wanted to clarify. What works in WA won't work in CA. You may actually make it in CA with a cat with your setup. It is amazing how much a cat helps.

Cheers, George

Hey George...remember Kevin, the guy who originally started the thread, is from NJ...not CA.

No question WA emissions are easier than CA...but everyone's emissions are easier than CA last I checked. Everyone said the SSIs wouldn't pass smog. They did. Drop the back dated SSIs and I supect I could pass CA enissions with little effort since any other SC does even with cams. You made a point about there being no secret cam profile for HP, which I might agree on, but I doubt there is much difference on the emissions test either.

Best part is I no longer have to test. Car is now 25 years old and exempt. No matter, I built the engine so it would pass emissions here :)

So what is "NOS" test anyway? And your point specifically on emissions with CIS?

John,
Here is where Tom did his dyno work.

"The dyno place was ATP Turbo in Fremont, 3 runs for $65. http://www.atpturbo.com"

Lots of folks congradulating Tom on his rebuild here.

http://forums.pelicanparts.com/showthread.php?s=&threadid=158331&highlight=dyno+r esults

My apologies Tom, but I have to ask. I am still asking myself what happened? May be a bad dyno machine calibration?

Scared the begeezers out of me as my engine (a dulpicate of Tom's) was just being finished as Tom posted this. Tom's engine should easily be 200/205 at the wheels and a bit more with twin plugs. His is the first, basic, short stroke CIS engine we have seen on Pelican.

Tom has a 98mm 3.2 with 9.8:1, twin plug, cams and SSIs

Here is Rennsport's conservative crank numbers from their web page:

3.0 CIS "SC" 74-style single 200-205
3.2 Motronic "Carrera" Cat-back single 220-230 (Chip)
3.4 Motronic "Carrera" Headers& muffler dual 240-260 High-compression & Chip
3.4 CIS "SC" 74-style dual 210-230
3.5 CIS "SC" 74-style dual 230-240 (Ported)

(my CIS 3.4 Max Moritz P&Cs with cam, SSIs and single plug is 219rwhp/258 crank)

Tom, I think the small ports are to blame. If it was me I would advance the cams to 2.0mm and build more torque in the engine. The pistons should handle the advance and I think the power will still peak at the same RPM.

I would also back up the original dyno pulls.

I use Dynospot racing for dyno work, even though ATP is about 3 miles from my house. I like the fact dynospot has the bigger 248H dyno.

Here is a '83 SC, mods '73 OEM exhaust, Triad 2in and 2 out muffler and a Webcam 20/21 grind. Engine was recently rebuilt to factory spec and is now well broken in. 173hp and 174# of torque. This is a good comparison for the early and late SC heads and the 8.5 and 9.5 compression pistons. Same day dyno as my 3.0.

Superman's '83 3.0 rebuild.
http://standingwave.org/albums/porsche/alr.sized.jpg

The 6.4% gain in displacement from a 3.0 to a 3.2 should get you 184 and 185 at the rear wheels alone based on Superman's #s and the other cars we dynoed that day. Twin plugs should add a bit to that mix as well. 190 would just duplicate BA's specuation that 225 was typical from the 98mm Max Moritz set up without the added hp from the cam.

The obvious point to me is Tom's isn't a MM P&C set, but the twin plug should maximise the RSR piston and the combustion chamber.

Dyno info is what it is (confusing at best for comparisons) but this one and Noah's make no sense to me. One is too high and one is too low by a good margin on both and it isn't the cam obviously since they are both 964 profiles :)

My guess is both great engines just inaccurate dynos.

Dane:

The point with NO is the following: You can lean out your mixture and achieve great CO and HC readings but you will pay for it because it will cause your NO to go up. That's all. So if there is no NO limit, it will really help you pass!

Cheers, George

Whoops, lost a number on the thread ID, fixed it.

In another thread I plotted the torque curves from a few different dyno runs. This one was the most interesting to me, Jim and Dane's runs. Jim (AKA Superman) 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 (which is exactly why Porsche did it), 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. Interesting.

http://forums.pelicanparts.com/uploa...1085160402.gif

As to my dyno run, I am less interested in the peak numbers than the shape of the torque curve. It really drops off after 4200 RPM, (down 20% by 6KRPM), I assume when the ports/runners start causing a restriction. On the plus side the restriction seems to help keep my AFR nice and steady. More air may have been too much for my stock CIS w/ Lamda, and I may have gone lean up top.

It is also interesting that my Torque curve and Jim's are identical from 5200 up.

Tom

Looks like the early heads are the way to go. Are there any dyno sheets on an early SC with sport sc cams?
I would still advance the cams in Tom's engine. If you are stuck with the small ports, you might as well increase the power in the useable power band.