Engine Build Dyno Results
 

So I finally got the results of my year-long engine build and install. The engine itself was done within a few weeks but the rest of the car took a while.

The engine has been run in and done a about 200kms at a few track days and a Supersprint.

I was hoping for a bit more power but I'm pretty happy with the torque curve, even if it lets off a bit early. You can see it was still making more HP at my self-imposed 6700 RPM. The dyno gear calibration was a bit low so it shows RPM about 100 low on the chart. I have standard valve springs in there so I am a bit wary of going much higher unless someone wants to endorse that...
I suspect the heads may be the limiting factor since the fuel/air mixture is spot-on and we spent quite a bit of time working on the spark map.

My fuel/spark maps are available for interested parties, e-mail me.

US 1983 34mm intake/35mm exhaust port heads. The intakes were taken out to 36.7mm and blended to the intake manifold.

3.2 Carrera aluminum intake & throttle body.

K&N filtercharger from a cummins diesel kit.

11:1 JE pistons
3.0 standard cylinders 95mm
SC crank.
US 1983 SC case, boat-tailed
twin-plugged fully controlled by ECU
Dougherty DR20 cams
Twin EDIS 6-post coils driven by triple-channel igniters
Innovate LC-1
26lb/hr Accel injectors @ 40lbs fuel pressure
rising-rate Edelbrock regulator
standard sc fuel pump
2-into-2 flowmaster muffler
bursch headers
Adaptronic ECU

John
Great to hear it has all come together.
How did your ignition maps end up?
Can you provide more detail on the Dyno results?
Paul

First is the HP/Torque at the wheels.

http://forums.pelicanparts.com/uploa...1181464496.jpg

Second is KW and air/fuel ratios.

http://forums.pelicanparts.com/uploa...1181464803.jpg

as soon as youtube posts the videos I'lll post those urls too

www.youtube.com files:

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Dyno clip


<object width="425" height="350"><param name="movie" value="http://www.youtube.com/v/2un_Il12ZTo"></param><embed src="http://www.youtube.com/v/2un_Il12ZTo" type="application/x-shockwave-flash" width="425" height="350"></embed></object>

Dyno run to redline

Heres a question. How do they get the numbers on the dyno. Do they try it in all gears or is it a certain gear they go to redline with?

My dyno operator selects the gear that gives a drive ratio closest to 1:1. On a stock SC 915, this would probably be 4th gear, as 5th is pretty tall and an "overdrive" gear, if I recall correctly.

176 RWHP does seem kind of low for all the mods to this engine. Does the Dyno Dynamics generally give lower readings than a Dynojet? I pulled 168 RWHP with a well-worn, stock '82SC motor on a Dynojet 248C a few years ago. An 8 HP difference doesn't add up considering the higher compression and intake mods, twin-plugging, etc.

http://members.rennlist.com/tweedt/dyno.jpg

Yeah. that seems low with all those changes.
As a reference my 2.5L motor with 10.5:1 pistons, single plug with 46mm PMO's put out 217HP at the rear wheels.

I concur it's low. My 81x66 twin plug, 40MM Webers, 10:1, 208 @ rear.

Does the weight of the car play into a horsepower reading? Seems like a lighter car would produce more power to the pavement correct? Im not into physics, just trying to comprehend.

no, it will just feel like it.

Please forgive me... So in turn, a lighter car with less Hp could beat a heavier car with more HP. I guess it makes sense now. My car would definitly beat my SUV. hehe

There is a significant difference in dynos, between companies, models, even the same models. I'm not so much worried about the absolute number as in comparisons to mods as I make them. An added bonus is these certified runs will help keep my power/weight ratio classification in a group I can be competitive in. The car, wet with me in it, at the starting line is 1040kgs.

I was also still making power up high and I suspect I'd hit higher numbers if I was wanted to push the redline up. I have new but OEM rod bolts and valve springs so I didnt want to push it.

The ratios and spark is well dialed-innow so the only real way to get more power now is through a mechanical change and that would mean the heads, bolts and springs. And displacement and boost (my other project). The Tech and I traded wearing the Det-Cans and we were never able to induce knock. The twin-plugging as I understand it won't get me any more horsies, just made it possible to keep adjusting the spark angle more and more advanced until power fell off. We then backed it off 2 degrees and did a few more pulls at that RPM and load again. If I wasn't twin-plugged at those high-compressions I might have been knocking before I got to the point of max power/spark angle. High compression and hot Australian track temps exacerbate the risk. Anyway, thats what the Internet told me.

To tell the truth (or maybe I'm in denial!) I'd really mostly happy the engine held together as it was my first full engine design and build. It gives me some confidence on the next project and in that case I've already made different decisions on that.

This is my first real race car so while I started out wanting a fire-breathing monster, but now having some seat time on a few different tracks and really starting to understand how the cars behaves (and a spin or two!) I am really happy with what I've ended up with: a very quick, reliable, easy-to-handle car that makes some awesome noise and gets attention at all the meets. The torque curve is quite broad, the scale on the graph at the top is a bit deceptive. It is very communicative and the combination of tires (Toyo RA1) and suspension/settings (Elephant Racing/Tarrett) makes it very "tactile." Instructors like the car too and it makes it easy to learn in...the throttle-position and brake LEDS show exactly what I'm doing and can be seen periphally while watching the road, you can hear EXACTLY what the engine is doing, and the cage/seat/harness system is very robust and comfy.

Anyway, so the absolute HP numbers don't thrill - 203 at the flywheel - but perhaps it will give others an example of what my build resulted in or maybe someone has a magic idea about how to find me another 30 hp?

John
Don't be too concerned with the Dyno results.
It is my understanding that the US chassis dynos are calibrated higher than the Australian chassis dynos. There is extensive background to support this difference in calibration.
For flywheel HP apply the following factors.
Flywheel HP = US Chassis Dyno * 1.15
Flywheel HP = Aus Chassis Dyno * 1.32

You did not respond to my earlier question re: the ignition map. How did the final map compare to the detail I provided earlier? Were you able to get more advance?
Paul

Thank Paul. Sorry, I must have missed your question. I did indeed start from your map, thanks so much. I did get some more advance but only a degree or two before power fell off. I did change the slope a bit. My ECU doesnt like to cut and paste maps...

10 deg cranking
15 deg 1000 rpm
16.8 deg 2000 rpm
25.2 deg 3000 rpm
27.2 deg 4000 rpm
28.2 deg 5750 rpm
29.2 deg 6000 rpm
30.2 deg 6250 rpm +

Those are all at WOT. at partial throttle I am sometimes advanced as 35 deg at 6000 rpm 0% throttle.


BTW, thanks. Your calc gives me 237hp, which is up 60 from stock. I'll choose to believe that number ;-)

John,

Your dyno results will also change depending on humidity and temp as well as heat soak on the day you tested.

My two cents

Michael

Hi John, well done.
I can definitley vouch for the low readings on Australian Dyno Dynamics chassis dynos.
I have a stock '84 Aust. delivered 3.2 Carrera which I had dynoed to get a baseline in case I decide to do some mods.
The result came back very disappointing, 155 RWHP which is not indicative of the car's performance. I'll post it up. Using the x 1.32 mentioned by John (Cruisesontrol) brings me to around 205 at the crank. I know this car personally is a 3.0 stock SC eater by a significant margin and also used to beat my friends 3.0 Carrera any day of the week.
I track the car reasonably regularly and last meet at Wakefield park I was arm-wrestling a slightly modded '78 3.3 930 with aftermarket turbo and RUF 5-speed. He was undoubtedly quicker down the straights but not shamingly so.
I later realized that (like many other Carreras) that my throttle linkage was poorly adjusted not allowing full throttle. I tested the WOT switch and it was being actuated. Maybe I was missing out on some indution air but I think I'll re-do it again now and let you know if interested.
BTW are you doing any PCNSW events?

Phil

John, thanks for the feedback on the ignition timing.
In response to Michael's post, I was told many years ago that HP difference relative to temperature is about +1% per 10degF (5.55degC) fall in temp.
Maybe, some one else could comment and also relate to the changes relative to humidity.
Paul

Hi John,

Congrats on your motor. Don't worry about the low #'s. The DynoDynamic and Dynapac dynos both give lower #'s than other dynos.

Do you like your ECU? And what made you choose that brand?

Dean

Hi guys, thanks for the comparisons.

It was 16 degrees and 54% humidity so the conditions were good for the runs. I did get my #4 head temp up to 310F so let it cool off but even then I was getting repeatable results.

Hi Phil, thanks for those. Yes, I've been doing some PCNSW activities. My car is track-only so I've not been doing any road events but I was down at Wakefield last month for the SUpersprint, to the Hi-tech muffler factory sizzle and to two Driving Solutions days. Went out to Alan's for the swap meet too.

Dean,
The ECU is Adaptronics, go to www.adaptronics.com.au I chose him because 1. his system does everything Haltech, MoTec, MSII and others do, 2. it cost me US$ 750.00, 3. the designer and company owner lives around the corner from me and 4. he does house-calls to install and troubleshoot. Plus he's a really nice guy. Oh, and he can build in custom features for you. Like for me he built in bluetooth so I can monitor, program and datalog the ECU from the laptop on my workbench.

I also built a megasquirt and will play with that some more.

That does seem very low, to me.
My 1985 was on a dyno a month or two ago.

This engine had never been rebuilt, and has no mods.

At the wheels, according to the operator.

http://wolfetone.com/911/dyno.jpg

Wow, you look REALLY lean there. Did you do any adjustment?

Talking to me? If so..no adjustment...

Wolfe, if you wish to keep the smile on your face, don't get these numbers checked at another dyno shop.
Paul

One of the books I have read suggests that this car came from the factory with 202hp.
The Porsche website says 231. I'm told they measure at the flywheel...adjust for transmission loss, and that's pretty close.

The car has 40,000 miles on it, so I would assume it's not very worn out. Compression and leakdown results were spectacular.
We'll run it again, and if the numbers are much different, I'll ask the first shop about it...

Wolfe, I understand your dyno HP numbers are at the wheels, not flywheel. The 1985 with engine Type# 930/21 has 207HP flywheel according to Bruce Andersons performance handbook. A June 1986 drivers manual shipped with a type 930/21 engine states 217HP (flywheel). The 217HP according to BA handbook came with the type 930/25 in the 87-89 Carrera. (yet a further discrepency)
The 231HP was for ROW type# 930/20 engines.

So unless you have type# 930/20, or previous owner(s) has done engine mods, the numbers you have are unusual. This is based on the flywheel HP = US dyno rear wheel HP *1.15

If you have a 930/21 or 930/25 I suggest using a DIFFERENT dyno to confirm your numbers.

I agree with John on the A/F ratios. The wide band O2 sensors / calibration, can also be out of wack.
Find another shop to get ALL numbers cross checked
Paul

Most dyno software will calculate these corrections automatically and include them in the output figure. I know the Dynojet 248C I tested on would do this to SAE specifications. Are the original HP figures shown for the Dyno Dynamics corrected or uncorrected?

The equation for the dyno correction factor given in SAE J1349 JUN90, converted to pressure in mb, is:
http://forums.pelicanparts.com/uploa...1181578170.jpg

where: cf = the dyno correction factor
Pd = the pressure of the dry air, mb
Tc = ambient temperature, deg C

The pressure of the dry air Pd, is found by subtracting the vapor pressure Pv from the actual air pressure, since wet air is less dense than dry air. It is the relative density of the air charge which effects the engines ability to make power.

Humidty is less of a factor in air density than temperature and air pressure, but it is significant. In playing with this HP correction factor calculator developed by a fellow in Colorado, I substituted values to change relative humidty by 10%, from 24% to 34%, while keeping all else equal, and the relative HP changed by .4%. At 100% humdity, however, it changed by nearly 3%. In comparison, a 30F change in temp (from 60F to 90F) yields about the same 3% change.

TT

John, I was looking at your AFR curve. I notice that the average is 12.2 - 12.4:1 through the rpm band. Looks good and flat. I might suggest you try to shift the entire curve(tuning map) up so that you run at 12.8-13.1:1. This will be more in line with peak power for a NA engine.

Otherwise your tuning looks good. I drove my EFI conversion the other day for the first time. It ran so much better than I expected and was surprisingly easy to improve on.

Considering the compression ratio, induction, and intended use of the car, aren't they really small cams ? Surely a lot of power is being left on the table relative to a set of DR60 or DR80 cams ? Of course if area under the curve and keeping peak power to a lower level for your power-to-weight classification is most important this may not be the way to go..

Craig H

The cams were originally meant for a street car. I just has a new-to-me 71 Targa arrive today, I might switch this engine over to the street car, put those solex cams in and put its weber 40's in that...

JohnJL,

I am in the midst of sorting out a top end rebuild for my stock US '82 3.0. And while the dyno you used may not have high numbers as compared to US dynos, (doesn't really matter a whole lot IMHO),

I'm liking the results.

You have 145 lbs of torque from 3200 RPM all the way to 6500. That is a killer torque curve for a street engine. From 5250 and above you have a nice horsepower peak up to 6400. I believe the shape of the curves is more important than the actual raw numbers.

My US 3.0 makes peak torque at 4600 RPM and peak HP at 5800 RPM. Stock SC cam with PMO 40s, SSIs and M&K muffler.
the car makes more torque than horsepower and I can feel that the engine runs out of breathe at 6 grand. My torque curve runs flat from 2700 to 5600. Nice around town, but theres no massive rush to redline.

I am curious whether you are using your stock 83 heads and had them machined for the second plug, or whether you chose the earlier 3.0 heads?

I am considering the larger intake heads and think they would work well with Camgrinders Mod S DC40 cam. Thats a bit more cam than you have, and I think you are at the max cam with Fuel injection. Correct? I'm not sure what your intake setup is.

In any case, the higher compression ratio improves the low end torque a bit and makes for a nice streetable engine. The last question I have is how does your butt dyno feel as compared to before the engine mods?

joe

Hi Joe,
I've been travelling, sorry for the late reply.

I used later 83SC heads, but smoothed out the ports to match the 3.2 intake manifold ports.