Had a fun day at Cresap Machine today in Cumberland MD on my good friend Dean's Super flow Dyno. In total, we made 34 pulls on my ZL-1. I had just put new rings and bearings in it to freshen it up and wanted to see what it would produce at the fly wheel (allready have chasis dyno results). I had the dyno for the entire day so I had the opportunity to test several variables. The variables were timing, air bleeds, jets, under car headers, and Hooker side pipe headers (with and with out muffler inserts).

Best results were obtained with timing at 36 total. Jets and air bleeds were adjusted for each exhaust combination to obtain a flat fuel delivery curve across the rpm range with A/F in the 12.5 to 13.1 range. The following summerizes the best results for the three exhaust configurations tested.

Run Pk Torque / RPM Pk HP / RPM
21 * 654.7 / 3600 642.0 / 6000
27 653.1 / 4100 631.3 / 5900
34 634.6 / 4600 632.8 / 5900

Run 21 was with under car 2" ID headers and no mufflers. Run 27 was with Hooker side pipe headers and no mufflers and run 34 was with the hooker side pipes and my home made 2.5" ID glass pack inserts.

It should be noted that we were not able to capture the peak torque with the under car headers (run 21). The dtno wouldn't pull the moter down below 3600 RPM and when you look at the plots it is clear to see that the peak is lower than 3600 RPM and greater than 654 ft-lbs. I was very surprised to see how much the Hooker side pipe headers shifted the torque curve (pk at 4100 RPM vs <3600 RPM). I was also surprised to see that the muffler inserts had little affect on peak HP but did kill peak torque by 19 ft-lbs.

I was very pleased with the results. The results show that the Hooker header side pipes with mufflers only loose about 1.5% Hp compaired to good under car headers with out mufflers. I think I will keep the side pipes because I love their song.

I have a vidio with great sound, some pictures and some jpegs of the plots if some one can post them for me.

 

Dyno day is fun, no wonder that car is so fast, way over 600 hp. What were your chassis dyno results. A bigger cam would make more power, 5900 rpms is a little low for peak power, even with a 4.25 stroke.

 

My last Chassis dyno results were 460 HP and 494 ft lbs. Not quite apples to apples but close.

 

great numbers!!

 

Thanks for that excellent writeup. Very, very informative.

To state the obvious, those are great numbers.

B.

 

Thanks GrandSportC3 and 300ZXTwinTurbo. The numbers were a little better than I expected. We started out at 585 HP. It is amazing how much affect proper tune has.

 

not a surprise.. I've spent some time at dyno shops and saw cars increase their power by as much as 70 RWHP after some tuning

 

Did you ever get someone to post those for you? I know many would like to see your goods.

Also, would you expect your chasis dyno numbers to go up with such precise tuning as you have now done with the motor dyno? What do you now expect?

B.