Street Dyno results for my dime

[jovial_cynic]

My engine build:

 

Bore size: 87.75mm (Z22E bored out .75mm)

Stroke: 86mm (L20b crank)

Headgasket bore: 88mm (that's a guess; I just figure it's gonna be 1mm over the stock bore)

Compressed gasket thickness: 1.2mm

Combustion chamber volume: 45cc (A87 open chambered head)

Piston dish volume: -9.32cc (stock Z22e pistons, but they are shaved down a bit, so this might be a little less)

Deck clearance: .2mm over deck (shaved down from .4mm)

CR: 9.58:1

Breathing with dual 38mm SUs

Timing: Initial-20, Total-36

Fuel Mix: O2 gauge says it's in the neighborhood, and quite rich during WOT.

 

Two early morning runs look like this:

 

(red: hp, green: torque)

 

Here's the full writeup: http://newprotest.org/details.pl?1431

 

I'm going to make some small adjustments to the timing and see if I can get closer to optimal, and after that's set, I'm going to make some small fuel ratio adjustments. But as a baseline, 111hp on the ground (138hp at the crank) for my first L/Z engine build makes me happy. And knowing that the 111hp is a pre-tuning number makes me think that I might be able to squeeze a few more horses out of it before needing to spend any extra money on it.

Edited October 13, 2009 by jovial_cynic

[bonvo]

that looks like a good base line but then again im parcial to low end tourqe rather then peak power i bet she feels quick

[69FJWagon]

your base timing looks a little high... Lisas LZ2.2 base timing is around 10 and full advance at 35 those arent bad numbers at all.

[jovial_cynic]

your base timing looks a little high... Lisas LZ2.2 base timing is around 10 and full advance at 35 those arent bad numbers at all.

 

When you say that the initial timing looks a little high, are you saying that you can tell it's causing some low-end power issues, per the graph? Or are you saying that 20 degrees initial just seems high to you?

[banzai510(hainz)]

111hp is VERY GOOD

try better gas and the timming and see what happens

[jovial_cynic]

thanks! I've been running higher octane gas from the start; I had a pinging issue because the vacuum advance was too high. I've since decreased the vacuum mechanism's throw, and trimmed the mechanical advance throw. This is all before I ran the dyno.

 

I think I'm going to reduce the advance just a bit to see which direction it puts me. We're getting rain soon, so I won't be able to make any runs for a week, I think. Breaking the tires loose throws off the numbers.

Edited October 13, 2009 by jovial_cynic

[Bleach]

over 100 foot pounds at 2000 rpm! Looks like a nice power band. Should be fun on the street.

[jovial_cynic]

Yeah - it chirps in 3rd gear (on DRY pavement, even!), which is exciting. I was concerned that I was going to lose some low end torque with the 2.25" exhaust, but I guess it works out alright. And I didn't really think about it until now, but since the torque goes from 100 at 2k rpms to 126 at 4k rpms, that's actually pretty flat, all things considered. It looks like it climbs and falls a bit, but perhaps that's only because of scaling.

 

Looks like anything past 5500 rpms is pretty much worthless, at the moment. I'll move my red-line indicator on my tach to 5500 to remind me not to go past that, since it isn't really useful to do so.

[69FJWagon]

When you say that the initial timing looks a little high, are you saying that you can tell it's causing some low-end power issues, per the graph? Or are you saying that 20 degrees initial just seems high to you?

 

seems to high to me but then again im not an engine builder... I am just going off what Troy shoots for when he builds and tunes an L series or LZ. If you look at Lisas Dyno graph in her build thread her torque curve stays flat till about 6300 as well as her AFR I would say you could get more out of it with some tuning for sure, I would be interested in seeing the difference between the SUs and a set of 44mm Mikunis :D I bet another 5 -10 whp at least

 

http://forum.ratsun.net/showthread.php?t=8150&page=5

[Bleach]

Are you going to lean it out a bit to see if that helps power above 5000 rpm?

[jovial_cynic]

The folks on the bb-list are advising that my total timing is what is actually causing some problems, not the initial... so I'll do some experimenting and see what happens.

 

They also mentioned that the dual 38mm SUs might not be providing enough air to the engine, limiting engine potential, so I'm already giving some thought to alternatives. Maybe 44mm would work, although going EFI is starting to look attractive, since some low-level forced induction might be amusing, and I'd much rather do that with fuel injection than with carbs.

 

 

Are you going to lean it out a bit to see if that helps power above 5000 rpm?

 

I've got a couple of variables to play with, so I'm going to pick one thing at a time so I can make sure I know what is giving me what results. But yeah - I've got that planned into my schedule. :)

[benzo]

congrats on your first build. not bad. what cam are using or spec wise? also you should look at switching to either some Z SU's modded from Z therapy or going dual mikuni's or webers 44's at minimum. I have a long rod 2.3 from Rebello and for sure can tell you it needs the 44's. I actually am supposedly running SK45's. Are you running 93 octane? I know most places outside of california provide that and if so that is good. I use 91 and had to watch the timing. For me it was easy I just follow what Rebello said and it is running fine. just maintaining it. I figured he is the engine builder. He was on dot with my hp #'s as I did dyno it and it made 140 whp but it was running rich hence Rebello made it like that to be safe running. I have not touched the jets but did move timing up a bit and made a difference but will not go more until I get my wideband out to check AF ratios and play with Jets. But for a small car the power you are making it moves still. good luck

[jovial_cynic]

Shadbolt cam: 510 lift, 280 duration.

 

I'm also going to pick up a wide band controller and do some air/fuel-over-RPM data logging and see what happens. But yeah - i'm hearing from everybody that my carbs are my current bottleneck.

[benzo]

I think the cam you have should be fine as your graph is not bad. For sure go with the different intake or yeah if you have money fuel injection or ITB's would be nice. EFI would make street driving nice and better on gas. you may not see much on the freeway. carbs are just simpler for some folks that's all but it seems you are pretty tech savvy so maybe look at that. For me I am planning to lose my nissan comp header and go with a stock man as there is no major difference in power just exhaust note. also my header hits my floor board a bit since it was meant for a L16. works but annoying at times cause it rattles. I don't care for much top end as I street drive a lot but on the street my car is fun and does pull hard. I have to date pegged my car at 120mph. my needle stopped but my friend was near me and said my wagon was movin good. have fun and keep us posted. nice work

[Bleach]

ya the cam sounds about as big as you want to go. Thats even more impressive on the torque curve with a cam that high of lift.

 

Many people default to larger carbs. I've seen some impressive whp numbers on 2.8L l-series with just SU carbs.

[benzo]

one thing have to remember is the 38 mm SU is smaller than a Z carb which If I remember is like 44mm. Steve Epperly at Z therapy made himself a LZ 2.2 in which he used the Z carbs try contacting him also

[jovial_cynic]

Looks like I might have a few minutes of dry weather today to do a couple more runs. I'm going to retard the ignition 5 degrees and see what that gets me.

 

Also, if anybody else is interested in running a dyno in their own car, I'll consider making circuits and selling them. The circuit simply hooks to the neg terminal on the coil, ground, and then a microphone jack plugs into a laptop or other recording device. Not much else to it, but it's a little bit of work to make the circuit, and to secure it all. If anyone is interested, let me know. It only comes out to about $5 in parts (for the wire, resistor, rheostat, connectors, and securing canister), but the time involved would probably be worth $15. I'll make them for $23 shipped, if anybody is interested.

Edited October 14, 2009 by jovial_cynic

[datzenmike]

Using an accelerometer?

[Skib]

Also, if anybody else is interested in running a dyno in their own car, I'll consider making circuits and selling them. The circuit simply hooks to the neg terminal on the coil, ground, and then a microphone jack plugs into a laptop or other recording device. Not much else to it, but it's a little bit of work to make the circuit, and to secure it all. If anyone is interested, let me know. It only comes out to about $5 in parts (for the wire, resistor, rheostat, connectors, and securing canister), but the time involved would probably be worth $15. I'll make them for $23 shipped, if anybody is interested.

 

Im interested in how this set up works, should post some pics and more info on it

[jovial_cynic]

Well, the circuit is this:

 

 

That's all there is to it. No, no accelerometer. It's just a voltage divider circuit that pulls signal from the coil, and the software processes the signal after you supply the software with all the necessary variables about the car and about the circumstances of the day on which you're driving.

[Skib]

could you go into some more detail on the software and setting up the variables?

[jovial_cynic]

The StreetDyno software asks for the following variables first:

 

number of cylinders

differential ratio

gear ratios

gear used in run

car weight

outside temperature

outside barometer

outside humidity

elevation

frictional losses

drag coefficient

front area

tire diameter

tire pressure

 

With that, plus the signal from the coil, it can extrapolate torque and then calculate horsepower. This site here outlines the math (towards the bottom): http://tinyurl.com/ykrj5am A couple of VR4 buddies of mine use the same formula and pull signals from their ECUs and run their data into an excel spreadsheet, and the curves are the same (should be; the formula is the same). From what I've read online, the numbers pulled from this formula are generally within 2% of what's being pulled at a "real" dyno. Errors tend to occur when, for example, a road that's assumed to be flat when it isn't.

[datzenmike]

Even if out 10% it would at least show increases/decreases when tuning, to at least show where something is going in the right/wrong direction.

[jovial_cynic]

Right - the runs are providing consistent data, and more important than being able to say that you've got xyz horsepower is the ability to actually tune your car and see what creates positive change. The goal, I think, is to reach optimal performance for your engine.

[benzo]

might be interested. keep me posted. I believe tuning on the street even though maybe not the safest or easiest is the best. I had my friends car tuned on the street and it ran very well. able to tune low rpm driving where it counts for daily drivers. WOT is only part of the story.