engine and drivetrain Finally Did A Little Dyno Tune Today

[Grover]

After installing Megasquirt four years ago, and ITB's about 6 months ago, I finally got around to putting the car on a dyno today. I'd spent quite a bit of time tuning the around town driveability to where I was happy with it, but never felt fully confident to do WOT pulls without being on a dyno with someone much more experienced making sure that I wasn't risking detonation or something.

 

Today I took the car down to see Rob Fuller, the owner of Z Car Garage in San Jose. I've gotten to know Rob via the Z that some friends and I run in Lemons, and he is the epitome of an enthusiast shop owner. I could swear that at some point he underwent some experimental surgery and had his veins and arteries replaced with a Z wiring harness.

 

Rob welcomed my 02 with open arms, although he couldn't refrain from a few kind hearted jabs about 510's beating 02's back in the day.

 

Long story short, we hooked the car up onto his DynoJet and made a few passes. Rob diagnosed that I was actually running too much advance in the upper areas of the spark map, but was too lean on fuel in the same areas. We tweaked the files a number of times between runs, and ultimately did a nice pull at the end that showed peak HP at 131.6 at 5,500rpm, and peak torque of 139.3 at about 4,600rpm, but a pretty nice torque curve all the way from down at 2,500rpm.  I'd guess this roughs out to something like 150hp and 160ft/lb torque at the crank, but I know it's a bit fuzzy to back calculate such things. As a point of reference, my car has a 2.3L stroker, 292 came (I think) and 9.5:1 compression, with 45mm TWM ITB's.

 

While there Rob was also curious to see how much the car weighed, so we put it on his corner scales (another first for me) and it looked pretty darned good. Total weight of smack on 2,300lbs (about 8 gallons of gas and a spare tire in the rear), with perfect 50-50 side to side weight, and 53-47 front to rear weight bias.

 

All in all, a fantastic day of fun!!!

 

 

[Chamonix72]

Interesting. I am planning to put my car on a dyno as well. I have slightly more cam, but less displacement than you have. I'm also running 40mm ITBs, dbilas in my case. I'm interested in comparing results (as much as you can across different conditions).

[Mike_B]

Very nice! I'm a huge proponent of dyno tuning (as you know from our emails) and I'm glad it was time well spent. I love the way your car has progressed and will even be more fun to drive with the added confidence!

Ray's always talking about the 4:10, you seriously need a Schrick 304! That stroker's gotta breathe...

[M3M3]

good job doing some tuning!

 

-since the ultimate "numbers" for the hp/tq are irrelevant due to the differences in dyno models, dyno operators and gearing, the real question is what was the difference between your first pull and the last pull?  was your street tuning close or were lots of changes needed at the shop to get to the final numbers?

 

-was the cross weight done with you in the car as it would be driven?  

[Palindrome]

Regarding the vehicle weight, is your battery still in the front or has it been relocated to the trunk between the strut towers?

[Grover]

The corner weighting was done with an empty car. It honestly came out of Rob's desire to see how it differed vs. a Datsun 510, which apparently weighed 2,200 from the factory. I claimed that this was also the weight of an 02 and Rob called BS and busted out the scales in good fun. Turns out I was off by a bit, but it was a fun exercise nonetheless. Palindrome, my battery is in the trunk.

 

MikeB, I agree that a cam is likely the next logical place to look if I want more power. The car drives very smoothly around town and idles very smoothly too at about 1050rpm, so I think I've got some wiggle room to go to a bigger cam and still keep it relatively comfortable on the streets (which is, realistically, where I drive it the most.)

 

Mlytle, here's a graph showing just the first and last pulls we did. You can see that in the first one that Rob aborted the run around 4k rpm as he could see that it was running too lean and also heard some indications of slight detonation. However, you can see that to that point we were running about 5pts lower in hp and about 10pts lower in torque. By the end of the day, we'd removed about 2 degrees of advance on average at the top, and increased the fuel by about 15% in the same areas.

[M3M3]

nice!  and that is EXACTLY what a dyno is good for.  measuring the relative change when tuning adjustments are made.

 

what were the target AFR's for WOT at upper rpm ranges?

Edited June 1, 2013 by mlytle

[Grover]

It's running at about 12.4:1 at WOT at 100kpa

[ray_]

It's running at about 12.4:1 at WOT at 100kpa

That looks real good!

 

Excellent torque and hp gain! Well worth the Datsun jibes!

 

;-)

 

Cheers,

[02Coastie]

Nice pulls! Dyno tuning definitely pays off. As an aside, I think the motor put down one heck of a torque curve, but is anyone suprised at the fall off of HP at only 5500rpm? I would have thought with 45mm ITB's and the 292 that you'd have power continuing up to 6-6.5k. I know it's not an S14, but still. Regardless, I'm sure it's one hell of a street motor.

-Lloyd

[roadhog0]

Can't wait to get MS on my car and take it down to the shop my brother works at and strap it to the dyno and have him help me get it tuned. Gonna be pretty BA!

[Colin]

Great stuff!  Can you share your spark tables?  I'm curious to see how they came out.

[Grover]

Colin. Here's where we netted out on the Spark Advance Table. We tried adjusting both fuel and spark advance to see if we could budge the hp and torque a bit higher into the rpms, but neither did the trick. As such, we backed things back down to where there was no additional gain, but a greater margin of safety for the motor. We also tried it both with and without the airbox and saw no more than a 1hp or ft/lb torque either way.

[Colin]

Colin. Here's where we netted out on the Spark Advance Table. We tried adjusting both fuel and spark advance to see if we could budge the hp and torque a bit higher into the rpms, but neither did the trick. As such, we backed things back down to where there was no additional gain, but a greater margin of safety for the motor. We also tried it both with and without the airbox and saw no more than a 1hp or ft/lb torque either way.

Wow this table is way different than I expected, much less spark advance.  I will try it.  Also, did he say why he has the spark table go all the way down to 400 RPM?

[Grover]

Colin. I set up those bins ages ago, having one that low was something to do with initial cranking, can't even remember any more honestly.