Reseda Dyno Day - Results

[Jack Olsen]

Tyson Schmidt, David Dorion and myself made it out to Strictly Dyno in Reseda, today, to get some baseline numbers for our engines.

Tyson's car has a 1972 911T with an MFI 2.4 that has hotter cams, and some other mild tweaks. Stock, his car should put out 140 hp at the crank. With his work on the motor, it's doing a little better than that:



David Dorion (DD74) has a stock SC motor in his 1974 911. His only mods so far are early (74) exhaust and a Triad dual-in-dual-out muffler. With a car as light as he's made his, the slightly-better-than-SC numbers are going to make it really scoot:



My 1972 911T has a 964 3.6, which puts out 247 hp in its stock configuration. With B&B headers, a modified (to eliminate the drone) B&B muffler, and the new No Bad Days Racing chip, it's doing very well. I was surprised, honestly, since it's doing the kind of numbers that Steve Timmins promises on his site. Usually, I scale a little ways back for all 'advertising claims.'



This is with the chip that Pelican board members MikeZ and Ingo Schmitz have been developing. I'll post my broader impressions in a separate thread (but let me say here, that the thing is good for a lot of horsepower.

We did 3 runs each, for $75. The good news was that there were no bad surprises. This wasn't the case for a guy with a 5-liter Mercedes who squeezed in between us. He'd had a stock 5-liter motor bored out to 6 full liters of displacement, in a long and frustrating experience with a tuner who eventually ended up in jail. New, number, at the crank? 314 hp. If his claim that the car came stock with 380 hp is true, then all his expensive mods ended up costing him 66 hp.

[911pcars]

Jack,
I was planning to be there with you, David and Tyson, but I came down with the flu; just came to my senses after three days.

Earlier, I tried to contact the proprietor of the dyno shop as to the format (strictly HP/torque runs or any time to fiddle?), but couldn't get through. BTW, the A/F ratios between all three cars is interesting. With MFI, CIS and DME represented, it would have been nice to get a carbureted engine in there as a comparison.

How long did the 3 runs take with setup?

Another day and another Dynojet (thus apples and oranges), my numbers were as follows:
Max power: 175
Max torque: 164
with 15% correction: 201 hp
No A/F scale
Testing stopped at 6K rpm due to an overrich condition. I was running 1.55 main jets, subsequently downsized to 1.45. Wanted to try smaller jets and perform a spark test to optimize advance curve.

General specs: 2.7 w/RS P/C at 8.5:1, E cams, ported heads and Weber carbs.

Hope this contributes to the database, and there will be a next time.

Sherwood Lee
http://members.rennlist.org/911pcars

[dd74]

The dyno process is quite interesting: the car is tied down very tightly after its rear tires are put on rollers. Specific calibrations regarding the car to be tested are programmed into a computer, and you are then asked what your redline is and in what gear you would like to test. The testing is very carefully performed, and the results were immediate.

Tyson and I tested our cars in third and fourth gear. Jack, I believe, was in second and third. My final horsepower results, as Jack posted, were while in third gear. I gained about four horsepower after Tyson retarded the timing a few degrees.

All-in-all, it made for a fun and informative afternoon. It's race car central in the strip mall where Strictly Dyno is located. Next door, a guy builds Chevy race motors. My ears are still ringing between our Porsches and the 1,000 hp drag motor the guy next door was running WOT.

Special thanks to Dan at Strictly Dyno, and thanks Jack for posting the thread.

[beepbeep]

Interesting numbers! I'm always surprized when i see nice smooth A/F-curves CIS is able to produce, despite being the worst FI in history of mankind. Same goes for 930's, nice smooth A/F with little lean-out at high revs.

That being said, it's inertial dyno, right? The one with big heavy rollers you spin up to certain revs and measure how long time it takes?

Well in that case there is no need to "guesstimate" transmission-losses, you can measure them directly by de-clutching and measuring the time it takes for rollers to deccelerate. That way you get exact loss-figure for your car and exact crank power, so i'm puzzled why you didn't have it done...?

[rdane]

Here is my '79 CIS SC with SSIs, a 2/2 Danke and a 20/21 web cam



and another Tom Tweed's..'80 SC with SSIs and a sport muffler

[jluetjen]

BeepBeep; In some respects it's what I'd expect. Remember that the CIS system is only maligned because it has 2 specific problems: 1) it inhibits the air flow and thus limits absolute HP and 2) the air meter gets confused by cams with a lot of overlap at idle. But in general it is a very flexible system that self adjusts for any changes in the cam or porting since it measures the airflow from idle to redline and meters the fuel to match. As long as you don't demand it to pump more fuel then it is capable or idle with radical cams, it'll work with you.

The MFI and DME are both mapped systems. The MFI is mapped on the 3D space cam and the DME has a digital map. So both systems work on the map designers assumptions for the performance of the engine. If the map matches the engine's charactoristics (generally this happens by design, not by accident) either system will provide the mixture accuracy of the CIS with throttle response that CIS could never match.

The is because when you tip in the throttle, both the MFI and DME "know" the amount of fuel for the new throttle position based on the map, while the CIS has to wait for the engine to change the vacuum in the plenem to cause the air meter to move and adjust the fueling. This could take at least 3 or 4 rev's of the engine by my estimates and constitutes throttle lag. Sure it's only few thousandth of a second, but you can feel it.

Did you notice that the torque curve for both the MFI and the DME engine dipped when the air-fuel mixture made a sudden dip. I wonder if these represent opportunities for improving the torque of the engine?

It will be interesting to compare the results with the Boston Dyno day once we have it. The cars hoped to be there represent almost a full factorial experiment.

- 1 stock 2.0E
- 1 2.0E with S pistons, but an E cam
- 1 2.0 with S pistons but normal (~E) pistons, ports and valves.
- 1 stock 2.4E

If we work it right, we should be able to charactorize the effects of cams, CR and capacity.

[dd74]

I appreciate the posting of other SC dyno results with which I am comparing my own. Now that I have a baseline, it is interesting to see the results of others' modifications and how much horsepower they achieved such as R Dane's and Tom Tweed's.

It seems factory heat exchangers do not put out the same hp numbers as SSI's, and possibly that is because the SSI's design allows for true equal length, while the heat exchangers are "almost" equal length.

After my run, Tyson and I discussed possible modifications, and figured that SSIs or headers, Early SC heads, 20/21 cams and Weber carburetors would be the way to go. We did not talk much about piston changes from the CIS version.

In regard to the Webers, we estimated a 10-20 hp increase alone w/o any other modifications. The early heads, 20/21 cams, and SSIs or headers, instead of heat exchangers should only enhance the Webers, and perhaps combine for 10-20 more horsepower.

What do you guys think?

[rdane]

"In regard to the Webers, we estimated a 10-20 hp increase alone w/o any other modifications. The early heads, 20/21 cams, and SSIs or headers, instead of heat exchangers should only enhance the Webers, and perhaps combine for 10-20 more horsepower"

I am right at 180 with SSis, 2/2 and a cam but no carbs. Next change will be 40 PMOs. That should make 190 at the wheel pretty easily. The dyno will tell the real story.

I suspect a higher compression pistons and the carbs will give us the 20hp I am looking for. No one I have spoken with says 20 for the carbs. Better yet adding a set of high compression, 3.2 pistons and an S cam would get us into the 275hp and 250 ft/lb of torgue according to Bruce Anderson. (page 151 of his Performance Handbook) But I suspect that is at the crank not the wheel. So I am looking for 230/240hp at the wheel to get that 275 crank.

Anderson also graphs a SC with early exhaust and stock muffler with 40 Webers @ 210hp/200ft/lb of torgue. Which would be 180 at the wheel. That would be a 15 hp jump on your car, as is, David.

Looks like the Webers are pretty much equal to the cam/SSI/sport muffler upgrade. Carbs (at least new PMOs) are just a bit more money in one bite

How about a group buy on the PMOs?


I like the torgue curve of the 20/21 shown in my dyno in comparison to a normal SC cam a lot. I am wondering what the 20/21 cam will do in the same 3.2 carbed setup. Anyone done something similar I would love to hear your results.

Seems every 1. in compression ratio will get you 10hp. Carbs 10 to 15 from the writing so far. Increase in displacement is by percentage. 3.2 should be worth another 6.6%.

Say 213hp at the wheels with euro P&Cs, carbs, SSIs, 2/2 and a cam.
Just add another fist full of money and stir! But that would be 250hp at the crank for an short stroke 3.2 SC. (Anderson says 275hp from this set up with the S cam!)

That seems to be where I am heading. I think I'll pass on the bigger cranks and save a bit of money. Unless I find something bigger that will work with a 3.0 crank looks like 3.2 is the top end. Other dollar limitation is higher compression or bigger P&Cs because of the costs of twin plugs.

[dd74]

R.D. - I agree with much of what you saying here. The reason I'd go with the Webers or PMOs out of the chute is because they're external, where the 20/21s aren't.

The rub is the 20/21s are, with a high-rev kit (valves, springs, etc), $1,100 less.

Still, there's the labor of the 20/21s, which will invariably be more than the Webers, I assume.

Great analysis, nonetheless.

[rdane]

David,
I agree, PMOs are a better performance upgrade out of the box. I have tried to keep the CIS for a fun car to drive and never worry about but my CIS has been a pain. If I had to do over again I would have just jumped on the PMOs. My cams came when I needed to reseal my case so the engine was out and apart anyway. Seemed like a good thing to do.

PMOs are next for my car. I want to see how they run on the 20/21 cam.

I am hoping for great things before I go off and buy the new P&Cs.

I would like to see a bunch more dynos on 3.0s though. The torgue #s on Toms' car are amazing. I'd like to bump my torgue curve up to 180! Keep us posted on what you have done.

regards,
Dane

[turbo6bar]

Dane, in looking at the dyno graphs for the 3.0s, I noticed your engine does not make good torque until 4000 rpm, but it holds great to 5500+, while the stock engine's torque drops off quickly, but also builds torque a little sooner. Did you 20/21 cams cause a loss in driveability at lower rpms, or do you always keep rpms above 3000-3500 anyway.

Looking at the graphs, Porsche HP is NOT cheap.

If Webers will add 20-25HP to a 3.0, will custom EFI also give the same? Or does one need to go with independent runner EFI to receive the gains?

Jürgen

[dd74]

Jurgen: interesting that you bring up electronics. This link:

http://www.clewett.com/

is to Clewett engineering. I called them a few months ago, and he suggested the induction system from a 3.2 adapted onto a 3.0 could yield 15-20 hp, if I remember correctly. The system includes some things that make the 3.2 induction system more adaptable to the 3.0 than if you tried to install it straight from a 3.2, though I don't know what Clewett's "kit" entails.

Nevertheless, it's a cool set up. One can run almost any cam a 3.2 can run within reason of the Motronic. The price from Clewett is about the same as a full PMO kit.

I wonder about two things:

1) Since I'm a lightness freak, I wonder if the induction from the 3.2 is heavier or lighter than PMOs or Webers.

2) I also wonder if one adapts the 3.2 induction to a 3.0, if that person can also "chip" the induction and result with even more horsepower.

Hmmm...this second question might be a good query for the 3.2 gurus on the board.

Here's a link to a thread discussing how to purchase PMOs; looks like Wayne's on top of getting them: Where to buy PMO carbs

[bigchillcar]

Anybody have any 2.7 CIS dyno results to show? Are there any header/exhaust related mods that could be done to a stock cis car that would improve over my already desireable stock exhaust?

From what I gather, cis is limited by both fuel and air delivery, especially mine which isn't an 'S' model and thus has smaller intake than the 'S' or Carerra of the same year. Would the use of a Euro 2.7 or SC fuel distributor and porting the heads improve anything or just reduce my available cash? Sure sounds like for keeping CIS, you have to avoid the cam overlap issue you might get with 20/21 or 964 grinds. Maybe RS pistons with their higher compression would be a way to go...do they work with CIS? Mod guys?
Ryan

[dd74]

From what I know, RS pistons work specifically with MFI.

[RoninLB]

Originally posted by bigchillcar
Maybe RS pistons with their higher compression would be a way to go...do they work with CIS? Mod guys?

I was using 2.7 Euro RS 8.5 pistons, w/CIS, w/2.7 Carrera dizzy

[bigchillcar]

Ron,
What are you running now? Aren't those 8.5's just the same as 'S' pistons? What about the Carrera dizzy...you mean the fuel distributor, right? is that the Euro 2.7 fuel distributor I've heard about and was referring to?

DD74...major brainfart...I'd forgotten...hadn't thought along those lines in a while.
Ryan

[RoninLB]

Originally posted by bigchillcar
Ron,
What are you running now?
Aren't those 8.5's just the same as 'S' pistons?
What about the Carrera dizzy...you mean the fuel distributor,

Hi Ryan..
I didn't have much dyno hands on to offer so I was just reading..

Presently
the previously rebuilt 2.7 is laying on the garage floor waiting for E-cams and PMOs. It was rebuilt about 50k ago with the RS pistons.. The S pistons are for the 2.4, or they can be the stock cast 2.7 pistons.. that's all I know about that..

the 2.7 Carrera ignition dizzy was cheaper to buy new than rebuild my stock CIS ignition dizzy.. I wanted the steeper low rpm curve for carbs anyway.

and the RS pistons/ C dizzy/ stock CIS has operated fine for about 50k miles..

I think that's it so far.......... Ron

[bigchillcar]

Hey Ron,
I've got the same little book (got it on e-bay), except that it's the 'Technical Specifications' for the 1974 models...I don't have access to a copier tonight, but let me know if you'd like some pages from it, they might be more applicable to your model as well.
Ryan

[dd74]

Ron: are those horsepower figures (210/154; 230/172) for the 2.7? How did you arrive to those numbers? Are they "guesstimates" or actual results?

Thanks.

[RoninLB]

Originally posted by bigchillcar
Hey Ron,
but let me know if you'd like some pages from it

OK.. thanks