Dyno sheet thread

[Pjackb]

Mr green on the Dyno

Story is here
viewtopic.php?f=2&t=34365&p=314737#p314737

Test details:
-U20,custom cam, 123Ignition, Mikuni PHH40 with 35mm venturi , LW flywheel , Air cleaners on , 91 octane , max timing 35 at 4K ( advancing timing further made basically no big differences)
-We initially made 116/129 leaning the pilots a slight bit gave us the final
-We tested on a Mustang dyno which as I understand it usually gives a lower number than a Dynojet because it is under load
- Since the engine has less than 1000 miles I asked the operator to stop each of the pulls a 6K rpm it was still pulling but power was tapping of anyway

[Solex68]

So what are the blue lines, the red lines and the green lines?

[Pjackb]

So what are the blue lines, the red lines and the green lines?

Blue Lines = Wheel Torque
Red Lines = Wheel HP
Green Lines = A/F Ratio

[sfdaugherty]

Here's a quick dyno update on my Sr20de Autech after installing Jeff's custom header. Rob Fuller at Zcargarage did the tune and the improvment in drivability is amazing. I took the car to lggpr in Kansas and autocrossed it and put it on the track. It was sooo much fun.

It now produces 171hp and 150 ftlbs of torque. Certainly an improvement over the last dyno of 161hp and 140ftlbs.

The engine is now with Rebello Racing to work their magic. Hopefully I'll have it back on the road by Spring. On my way to Solvang, it will go back to Rob for another tune which will include E85 this time.

Shannon

[Pjackb]

Here's a quick dyno update on my Sr20de Autech after installing Jeff's custom header. Rob Fuller at Zcargarage did the tune and the improvment in drivability is amazing. I took the car to lggpr in Kansas ans autocrossed it and put it on the track. It was sooo much fun.

It now produces 171hp and 150 ftlbs of torque. Certainly an improvement over the last dyno of 161hp and 140ftlbs.

The engine is now with Rebello Racing to work their magic. Hopefully I'll have it back on the road by Spring. On my way to Solvang, it will go back to Rob for another tune which will include E85 this time.

Shannon

Cool, what are you having Dave do ?
it will be interesting to see the differences on the same dyno after the work

[Gregs672000]

Wow, you must be very pleased, that's a great improvement! Very interesting plot. The Autech is a variable cam timing head, right? Look how it makes a nice torque peek at 4800rpm or so, very much like a B or C crammed U20. Then the variable cam timing kicks in and the engine changes and bumps the torque peak up 10ftlbs 1000rpms later... it's like two engines in one! I've experienced that change in the 2000 Toyota Celica GTS I had, only it happened later and redlined at 8000rpm. It really shows that the cam is the "brain" of the engine, and two brains are better than one! Variable cam timing design was a major improvement.

The two run plots showing before and after tuning also says volumes about Rob's tuning ability. Just adding the header helped, but it took more than just bolting something on and calling it good to see 10ftlbs of improvement. Very nice Work!

I wonder what causes the torque drop between 3500 and 4500rpm. Did you see that previously? I wonder if this is an area that Robello will pay attention to. It would be very interesting to see what's happening regarding ignition timing and air to fuel ratios during that time, or if a change in the initial cam profile would smooth that out. We'll stay "tuned" so to speak!

Really cool, I bet she's a blast! Woo HOO, HIT IT!

[sfdaugherty]

I'm waiting for Dave to tell me what he thinks it needs. At a minimum he'll work the head, maybe cams, balancing, etc. I did not have that dip in the torque curve previously. My hope is not to achieve the highest horsepower but good power and easy to drive on the street.

Rob is really extraordinary. This dyno run was BEFORE he went on the street and started putting in more and more timing and adjusted fuel curves. I suspect the final numbers would have been better. He had me holding the computer on my lap watching the knock sensor and it never knocked once.

The engine was rated between 197-200hp from the factory (depending on who you ask). Estimating 15-20% drivetrain losses, I'm getting 201- 213 at the crank right now.

My goal is 200hp at the wheels. Power deivery is very linear. It's not a turbo but it think it's enough power and torque for me. I can spin both tires at launch through my rx7 lsd.

I will post links to some of my lggpr runs. The sound is fantastic!

[Gregs672000]

I did not have that dip in the torque curve previously.

And another example that an engine is a system... changing one thing affects others! Once one realizes that, you look at claims on the Internet or just bolting on something "bigger and better" in a different light. Even very well engineered pieces typically need tweaking to get the best result. I've watched my engine evolve over time, with ups and downs, but I've always maintained that the jury is still out as to what worked and what didn't (I do know too much compression with pump gas is a mistake) but... I'm not done tuning! Fun stuff! Excited for you!

[Alvin]

Here's a quick dyno update on my Sr20de Autech after installing Jeff's custom header. Rob Fuller at Zcargarage did the tune and the improvment in drivability is amazing. I took the car to lggpr in Kansas and autocrossed it and put it on the track. It was sooo much fun.

It now produces 171hp and 150 ftlbs of torque. Certainly an improvement over the last dyno of 161hp and 140ftlbs.

The engine is now with Rebello Racing to work their magic. Hopefully I'll have it back on the road by Spring. On my way to Solvang, it will go back to Rob for another tune which will include E85 this time.

Shannon

Shannon,
I'm glad you made the trip all the way from NM to San Jose! Wish I could have been there for the dyno session. Looking forward to your return and more power!

For reference, here is another Autech SR20 (in a Miata) that Rob dyno'd, it was not a full tuning session but it made 179hp/149tq at the wheels:

The tubular exhaust header on Diamond's Autech:

The Autech is a variable cam timing head, right?

Greg,
No, the Autech SR20 has Variable Timing Control (VTC), valve lift and duration are NOT altered.
The SR20VE is the model that has variable valve timing, switching between two different sets of cam lobes..like Honda's VTEC or your Celica's engine.
The SR20VE makes 200+whp easily. This is what Mike (RCMike) runs in his roadster.

[sfdaugherty]

Alvin:
I'll make sure to let you know when I get the tune scheduled.

Now this is good information! I'm fascinated by the similarities and the differences. It has similar drops in the torque curve but continues to make power up to 7000 rpms when mine drops off. I love the original header. Too bad it won't fit in a roadster.

[Gregs672000]

Oh, that's very Interesting! So the system changes cam timing but isn't two cams in one eh? I'll have to research what makes the Autech version higher performance over stock. Still pretty cool! The 20VE sounds freakin awesome when it transitions to the higher lift and duration lobes. Thanks for the clarification.

On a related note, as is known, my motor is too high compression for pump gas without pulling out and controlling timing very carefully. However, I have been reading up on octane boosters and find that Boostane appears to be the real deal and actually quite economical if you only need to go up a few points (93 to 96). According to their mix chart you would only need about an ounce per tank, and the $30 can is 32 ounces. A buck a tank! This is for the race only version, the street legal is twice the amount used but costs a bit less per can, but not half. Still, if this is correct, it's way cheaper AND more effective. I'll be getting some and will report results in conjunction with the conversion to EFI in the spring.

[Alvin]

Oh, that's very Interesting! So the system changes cam timing but isn't two cams in one eh? I'll have to research what makes the Autech version higher performance over stock. Still pretty cool! The 20VE sounds freakin awesome when it transitions to the higher lift and duration lobes. Thanks for the clarification.

The VTC system is on many Nissan engines. On the S14/S15 and Autech SR20 the VTC works through an oil-pressure activated solenoid to advance the cam (intake cam only) relative to the sprocket. Details on the Autech version are sparse but a few mods boost power: aggressive cams, tubular exhaust header, ECU, higher compression.

[Gregs672000]

I looked the engine up over at engine-specs.net/nissan/sr20-de. I noted there are three different versions of Autech, as well as several SR20 versions. What stood out was the earlier versions had a higher duration cam, and as the engine progressed they kept dropping the duration down further, resulting in a lower rpm torque peak. Your peak at 5600+ matches that of the early, higher duration cam. The Mazda conversation shows the lower duration cam I think, at 4800 rpm peak. Maybe?

[sfdaugherty]

I suspect that the lower horsepower and torque Autech engines listed were used in the front wheel drive versions. I don't know for sure but that's my guess.

I've asked Rebello to measure the cams to get the lift and duration and determine if more agressive cams would be an improvement.

[Gregs672000]

I'm sure there are a few other changes that go along with different power ratings, but the cam difference is noticeable. And they reduced duration while ultimately making more torque at a lower rpm. I would say cam choice is very much in play. I do see that later SR motors ran a roller rocker, offering perhaps different cam profile options. Should be fun!