dyno tuning results
 

Many years ago I did a bunch of testing and tuning on a dyno jet chassis dyno. I was looking over that information and thought I would share a little of what I figured out. All the testing I did was on the same Dynojet dyno over a period of around 3 years. Testing was done on multiple cars and multiple configurations. The start of the testing was on my 78SC. The car had a stock motor but had a Carrera 3.2 intake manifold with programmable fuel injection with ignition control. Exhaust side was SSI heat exchangers with factory early muffler with second outlet. Cam timing was at the far retarded end of specification with the hopes of best power. This is a graph of the first run.

http://forums.pelicanparts.com/uploa...1510880938.JPG

With some changes to fuel and ignition I was able to get some improvements but still had a big torque hole from 3K to 5K. Below is a graph after the first round of tuning vs very first run.


http://forums.pelicanparts.com/uploa...1510881209.JPG

I was pretty happy with the results of that day and was convinced dyno tuning was the way to go.

john

the next thing I decided to try changing was the cam timing. I started advancing the cam timing to see how it effected power. Each time I advanced the cam timing the torque and HP improved. In the end I ended up with cam timing just a little over the most advanced factory specs. I was worried about going to far and having the valves hit the pistons. Knowing what I know today I should have measured what piston to valve clearance I had and kept advancing until clearance got to small or I started loosing power. Below is a comparison from best run in first tuning and best after changing cam timing.



http://forums.pelicanparts.com/uploa...1510882322.JPG

So from the start of this tuning I was able to go from 170 to 188 hp and 151 to 172 torque with out changing any parts.

john

I drove the car this way for a while. I did lots of DE events and got other people in the club to do some dyno tuning. I put together a dyno day for the club and we ran lots of cars. Below is a graph testing three different muffler configurations. The first run (blue) was my early muffler with second outlet. Second ( Red) was with open megaphones and third (green) was with a early two in single outlet muffler. I ran the dual outlet muffler the rest of the time I owned the car as I never found another configuration on my car that worked any better.

http://forums.pelicanparts.com/uploa...1510882949.JPG


john

If you are wondering how bad a muffler can be see below. This was not my car but a fellow pelican who had built a muffler using two glass packs. This was on a stock 3.0 engine with headers. The thought was that glasspacks were straight thru and light weight "How bad could they be". The graph below is the glasspack configuration vs megaphones done on the same day.


http://forums.pelicanparts.com/uploa...1510883258.JPG

The glasspacks were costing 30HP and 17 ft/lb torque

john

One of the things I was impressed with was the repeatability of the dyno jet. The graph below is two runs of my car 4 months apart with no changes.

http://forums.pelicanparts.com/uploa...1510883782.JPG

As you can see very repeatable.

john

As I was doing more DE events I decided to take my car back to stock and reinstalled the factory CIS. The CIS is not nearly as good as the 3.2 manifolds. Below is a graph after I reinstalled the CIS and tuned.

http://forums.pelicanparts.com/uploa...1510884008.JPG

I was sad about the power loss going back to CIS.

john

I sold my 3.2 manifolds and injection system to a friend who installed it on his motor. He had a 2.7 with RS pistons and E cams running on stock 2.7 CIS. He was happy with the power increase with the 3.2 manifolds.

http://forums.pelicanparts.com/uploa...1510884257.JPG

The stock CIS was chocking this motor.

john

A missed shift at a DE which resulted in a motor rebuild. Heads were redone with new valves and valve job. A good set of used 9.3 Mahle Pistons and Cylinders were installed. Cams were reground and rockers refaced. End result was much improved power. I continued with trying to find little tweeks for the CIS system as I knew it was costing a lot of power (over the 3.2 manifold). I also started club racing. I tweeked the warm up regulator to the low end of specs to try and have the CIS plate open more. I used measuring vials to measure output of each injector and tweeked the adjustment (I had a 78 Euro fuel head) at each injector so they were the same. I modified the air cleaner cover with an extension the sealed against the tail I had to pull in only cold air. In the end I was happy with the result. Graph below is best before rebuild and best after.

http://forums.pelicanparts.com/uploa...1510885063.JPG

john

Graph below is another very nice running 3.0 built the same as mine. Both were early big port heads with later 9.3 cylinders, headers and same muffler.

http://forums.pelicanparts.com/uploa...1510885443.JPG

output is pretty much the same.

john

The graph below is where I started. Tired low compression SC motor with non-optimized cam timing, ignition or fuel. End is fresh motor with CIS tuned as good as I could get it. I would have loved to see what my fresh high compression motor would have done with the 3.2 manifold and injection. I am a big fan of tuning on the real dyno as opposed to the but dyno. Most of these graphs are from around 2000 when dyno tuning and programmable injection was not as common as today.

http://forums.pelicanparts.com/uploa...1510886030.JPG

I hope you found this interesting and use it as inspiration to tune your own car and separate facts from fiction.

john

Thanks John. I would have never thought the CIS hit would have been so large! Rob

that is shocking that the straight through glass packs would cost 30 HP!

I wonder if there is something else going on there?

The glasspacks were the cheap (bad ) style where there is punched metal that stick into the exhaust flow (like picture below) . I think if they were of the style with just holes in the tube they would not have been as bad.

http://forums.pelicanparts.com/uploa...1510897131.jpg

john

Great thread


Sent from my iPhone using Tapatalk

Thanks for posting your results John, very interesting read. The cam timing settings and muffler numbers show where easy gains (or losses) could be found.

Is the dyno HP result calculated at the engine or rear wheels.

A dynojet is chassis dyno. All numbers are at the rear wheels.

john

targa,
Thank you for posting your dyno results. A well documented and informative thread.

regards,
al

Thanks John - interesting results . Which Dynojet shop in the Denver area did you use ?
Regards, JD

I used Dyno pro in Aurora

john

Can't believe I only just found this thread. Brilliant information, thanks.

Instinct................
 

Good info all! When I built my SC motor into a 3.3SS, I used 964 cams and set them right at the max advance point. I was assuming that the extra displacement along with almost 11:1 compression would make up the otherwise lost low/mid range torque and allow for good top end power. Turns out that is exactly what happened. Sometimes it is better to be lucky than good!

This thread is also new to me, and fascinating.

Question for the Knowledgable: In this series of graphs, when the OP went from his 3.2/digital F.i. back to CIS, are we seeing that the CIS yields more torque and power in the ca. 3500-4500 RPM area? If yes, is that the kind of thing which can be overcome/improved upon in the digital set-up by tuning for better mixture and/or timing values in those specific areas of the RPM range?

Thanks to the OP for this format, very educational.
John/CT

Yes, the CIS made better power from 3.5-4.5K. I don't know for sure but my guess would be it is probably due to the CIS runners being smaller than 3.2 manifold runners and the air flow not being large enough for the CIS plate to restrict power. It would be interesting to see someone who did the BLITZ EFI system with CIS runners and then switched to 3.2 Carrera manifolds to see what the difference looks like.

john

How much cam timing did you go to?

This is very cool. 1982 stock cis was 1.6mm

I’m curious as to how far you went to get such a nice improvement.

The cams were installed at the most retarded factory spec. I started advancing the cam timing to see how it effected power. Each time I advanced the cam timing the torque and HP improved. In the end I ended up with cam timing just a little over the most advanced factory specs. I was worried about going to far and having the valves hit the pistons. Knowing what I know today I should have measured what piston to valve clearance I had and kept advancing until clearance got to small or I started loosing power. I had some friends that changed there cam timing to most advanced spec with similar results (all 78-79 big runner/port engines).

john

Hi
when you did advance the cam timing, did you pull the engine each time? Did you have to pull all the rockers except cyl 1 & 4?
Reason I ask, is I am tempted to do something similar..

You can fiddle with the cam timing with the engine in the car... its a bit of a PIA, don't have to remove the other rockers, just back the adjustment screws all the way out on the rockers

BTDT at the track at 2:00AM

Like others have said, I just found this thread. Great work, Targa72e, and thanks fore posting the dyno graphs. I've had way too many arguments with people who didn't have actual data to back them up. This is about as good as anyone could ask for.

I also have adjusted fuel distributors on other CIS cars to get equal output at each injector. It appears to also make the engine run smoother.

Pardon me while I run out to the garage and advance my cams...