Dyno testing 308 P6 cams, borgo hi comp pistons

Having resolved to do the dyno testing in another thread here, I have gotten pricing from 2 different locations here in Houston- one is a dynojet -3 pulls for $75 and the other is a Mustang 3 pulls for $100. Both have said they will schedule me for a slow day so that I can change jetting/timing in response to the results. I have never had a car dyno'ed before so have a very fuzzy idea of what I am doing.

Live in the Houston area so would be looking for any input on shops etc that local members might already have. Have posted in the Texas section as well.

So that the information I am getting ready to generate might be of some value to the discussions concerning P6 cams and hi compression pistons I thought it would be worthwhile to solicit your thoughts recommendations prior to launching the effort. I will of course document my initial settings and then strive to only change one variable at a time to isolate its effect on hp/torque curves. Please let me know your thoughts this week as I am scheduled to do testing on the Mustang next Tuesday. Perhaps it is worth testing on both machines to see how different the results would be, realizing that testing the same car on different days with the same setup will acheive differing results etc. All of which means to me that the value in comparing results between different machines and different cars is is dubious at best. I am doing this to satisfy my own curiosity as to what the results of the engine swap/upgrade I made 5 years ago in fact were and figure out, by iteration, if I can improve upon the timing/jetting I have in it now. If the results can further the discussions here all the better


Don

 

Photos of the Borgos going into the dry sump engine.
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Did not measure deck height as I left that to the engine builder. One more pic of pistons attached.

Don
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Well, I am still waiting for the dyno guy to send me the records of the dyno runs I did on Thursday.

My first pulls were just under 200 hp at the wheels and after getting the A/F ratio down from 14 to low 13/hi 12 we got it to read pretty consistently at 216 hp at the wheels. Adjusting the timing got the last bit of hp out of the engine. 12* static, ramping up to 32* at 3000 rpm and then ramping up another 2-3* at 8000 rpm was the right ticket. Pushing the timing above 36-37* resulting in losing power at the top end. When I get the curves emailed to me I will post them for all to see. Having the direct fire ignition really made it easy to tune at the end

For the record the carbs were jetted initially at

Idle- .60
main - 125
Air corrector- 180
Emulsion tubes- F24

This was found to be too rich down low, and far too lean at the top

Best runs (215-216 hp) and a very smooth power band were found to be at:

Idle - .55
main- 135
Air corrector 195
Emulstion tubes F24

The .55 idle jets are still a bit too rich but I don't think it will run on .50 idles unless the screws are backed out to the point where they would start to fall out. It took me about 3 tries to get the jetting right, changing the jetting between sets of 3 or 4 pulls. Usually would take about 20-30 minutes to change mains and air correctors with another 10-15 minutes for the idles. Only changed the idles once as the most work needed to be done up top.

If I figure 18% drive train loss then I am thinking the engine is putting out 263 hp at the crank. Looking back at the guesses made earlier in this post it is pretty amazing how close they were to the final result. Again, when I get the graph output I will post for folks to view. All pulls were done in 3rd gear which the dyno guy said would be best.

As a side note the guy with the dyno here in Houston had had the Pantera club come over a few weeks prior and spent the whole day there. I thought that their runs would be far in excess of my Ferrari given their significant displacement advantages. Amazingly enough, most of the Panteras were running 200 to 230 hp at the wheels and the best one was about 258 at the wheels or just barely 300 crank hp. And their power bands were all over the place, downright pitiful most of them. Guess these little 3L motors are not that bad after all. I can' wait to see what mk e can do with the 208 head that I sent him this week. Someday I would like to try them on this engine and see where it gets me.

Don