28 replies to this topic

[OctaneNation]

There's a few of us new to SM racing in a region that previously had no SM class to speak of, so we are getting up to speed on all things SM... and a large contingent have 1.6L cars.

 

We started some 1.6 dyno development last week (224x Dynojet, SAE correction) and have yet to break 100 ft-lbs, including a car with a brand new complete pro engine. The best it's done is 116/100 with 'scary' ~14:1 AFR at 5k RPM.

 

A few questions/observations.

 

1. Hood up vs down has a significant impact on power. Seems everyone dynos with hoods up, even though it would appear less representative of actual racing. Why?

2. How much base timing can a 1.6L tolerate in race trim at max CR? 16 base sound reasonable?

3. How lean do you dare run these things at 5k?

4. We rotated AFM 45 degrees. Loosened clocksprings, moved wiper and adjusted fuel pressure. 12 clicks looser netted us a surprisingly flat AFR from 5k to fuel cut. However the AFM spring at this point is so loose that it can't even close the flapper with the engine off. Is it possible to run an AFM this loose on the track?

5. At a 'normal' 7 clicks loose (from memory) there's a 2 point AFR spread from 5k to fuel cut that everyone seems to talk about and accept, which led us to try to improve.

6. How the heck is 126/110 possible from a legal 1.6???

7. E10 or E0 fuel recommended for best power? Widest margin of tuning? Coolest running? E10 seems to be the best for all 3 unless I'm missing something.

8. 180 degree tstat/running temp recommended as a target?

9. Any big things we're missing?

 

Cheers,

Matt

[davew]

Sooooo many things you are missing or not taking into account.

Every dyno is different, every dyno jet is different, every brain box that dyno jet makes is different, every drum that dyno jet makes is different. Comparing my apple to your apple from 100's of miles apart is almost worthless.

Weather conditions, temp, humidity, baro. Correction factor is not that good at correcting.

Outside issues, how tight are the straps, what tire pressure, what tire brand, what allignment.

Engine issues, fuel brand, e-rating, winter blend vs summer blend, emmisions blend versus non emmisions blend. For me, who lives in Illinois but works in Wisconsin, difference between Illinois gas and Wisconsin gas.
Engine oil, I have seen 12 hp difference in oil
trans fluid
diff fluid
driveshaft angle
alternator bearings
weak battery
weak ignition system

Equipment issues, accurracy of timing light, accuracy of lamda sensor, accuracy of timing pointer/balancer on the car

Brake drag

Lookk at all these issues. Then compare your car to a known quantity car. You may have no issues except a low reading dyno.

dave

[Steve Scheifler]

Not sure what all was meant to be included in that 12hp number but probably not just engine oil unless we're including very low viscosity casing soft HLAs. Other than that, yea, hard to compare without knowing a lot more. Shops that do a lot of these cars can control more of the variables and give you a better sense of where you stand.

Regarding hood up/down, unless you have a wind tunnel then hood down is even worse than up because you can't simulate moving through the air at speed with a simple fan and heat builds quickly. Best to keep it up with an extra fan blowing air across it to maintain a more consistent temp at the filter whether high or low.

I have yet to see too much timing make more power overall. There tends to be about a 2 degree plateau before power starts dropping again so we tune to the low end of that range. Pretty much the same with AFR if you watch total power under the curve because torque tends to suffer as you plateau on HP. But that was before being allowed to adjust fuel pressure which should help a bit.

Your numbers are still at or slightly above what we see on the Dynapack, which is a very different animal.

I would be very interested to know how long a pull is taking from say 4K to 7k or whatever range you can quote at full throttle. If you can give me the exact seconds and RPM points I can simulate on mine. I'll be on the dyno much of today (Monday).

[Bench Racer]

Your numbers are still at or slightly above what we see on the Dynapack, which is a very different animal.

 

Steve, my 1.6 numbers on the Meller/Loshak DynoPack are closer to the numbers that Matt mentioned 126/110 (actual 127/108). Explanation???
 

[Ron Alan]

Ummm...you have a cheater motor Dave!

[Steve Scheifler]

Hard to say Dave, maybe our engines are really that far off and we're super heroes to have been as competitive as we were. Not likely since we seemed OK on the straights. But if you have Dynapack data I'd sure like to know more about it. Do you know how long the pulls were and for what RPM range?

[Bench Racer]

Ummm...you have a cheater motor Dave!

 

Tough crowd Ron, Drago/Buras have/had a Drago engine at IIRC 127/110 or very close on a Drago's roller dyno.  They must of been less compliant than me.

 

Steve, had a pc crash BIG TIME a few months ago and lost the files. After this holiday today I'll call Mark Meller for a new set of files and I'll ask about pull time. IIRC the pull started around 4,500-5,000 rpm through 6,800 rpm. After 5,000 rpm, maybe 5 seconds??????  < Please note all the question marks. Dyno numbers are dyno numbers as long as one uses the same dyno with no changes to the dyno. If your numbers were 116/100 what would an OEM stock engine numbers be?
 

[Steve Scheifler]

No idea what stock would be on this dyno.
Steep re-learning curve playing with AFM. Octane, did you also loosen the Allen and twist the wiper assembly clockwise in the slot? I keep thinking there is also a way to loosen the clamp and turn that a bit more on the shaft but not willing to force it at the moment so the wiper still gets far enough to go rich at the top. I thought there was another slotted plate somewhere but don't see it now. Need to dissect a dead one again.

[Steve Scheifler]

Pulled from other topic...

...

Talked with Mark Meller, he did mention calibration can make the same mfg. dyno results different. Same dyno still shows pluses or minuses for changes.

4,000 rpm to 6,873 rpm, 8 seconds, 109 lb ft at 5,700 rpm, 127 hp at 6,800 rpm.

Using those exact RPM and length of pull I get 103 lb ft and 114 hp. That's not minor calibration differences.

Are you really seeing peak power at 6800??? We typically reach peak by 6200, plateau to maybe 6600 if we're lucky, then drop at least 3-4 by 6800. It's partly that AFR goes rich up there but even without that ours would run out of breath before then.

[Bench Racer]

Steve, as soon as Mark sends the files the info will be available. Post then and will attempt to send you file.

[OctaneNation]

Been busy prepping the car but I'll respond to some of the above posts...

 

Sooooo many things you are missing or not taking into account.

Every dyno is different, every dyno jet is different, every brain box that dyno jet makes is different, every drum that dyno jet makes is different. Comparing my apple to your apple from 100's of miles apart is almost worthless.

Weather conditions, temp, humidity, baro. Correction factor is not that good at correcting.

[...]
Lookk at all these issues. Then compare your car to a known quantity car. You may have no issues except a low reading dyno.

dave

Our typical barometer reading is 27.5", with a CF of around 1.06. I can certainly appreciate the limitations of a correction factor, but we are still ~10% shy on the pro motor. We have a couple stock '99's that we plan to use to help 'calibrate' the dyno.

 

Regarding hood up/down, unless you have a wind tunnel then hood down is even worse than up because you can't simulate moving through the air at speed with a simple fan and heat builds quickly. Best to keep it up with an extra fan blowing air across it to maintain a more consistent temp at the filter whether high or low.

I have yet to see too much timing make more power overall. There tends to be about a 2 degree plateau before power starts dropping again so we tune to the low end of that range. Pretty much the same with AFR if you watch total power under the curve because torque tends to suffer as you plateau on HP. But that was before being allowed to adjust fuel pressure which should help a bit.

Your numbers are still at or slightly above what we see on the Dynapack, which is a very different animal.

I would be very interested to know how long a pull is taking from say 4K to 7k or whatever range you can quote at full throttle. If you can give me the exact seconds and RPM points I can simulate on mine. I'll be on the dyno much of today (Monday).

Hood up vs hood down makes a big difference. Same with coolant temp. We will install aftermakret gauges to get that more accurate and repeatable for doing pulls. 

Comparing to Dynojet to Dynapack is opening a whole 'nother can of worms...which is part of the reason why we're using a Dynojet. It seems the most common which helps in benchmarking.

 

No idea what stock would be on this dyno.
Steep re-learning curve playing with AFM. Octane, did you also loosen the Allen and twist the wiper assembly clockwise in the slot? I keep thinking there is also a way to loosen the clamp and turn that a bit more on the shaft but not willing to force it at the moment so the wiper still gets far enough to go rich at the top. I thought there was another slotted plate somewhere but don't see it now. Need to dissect a dead one again.

As an experiment we loosened an AFM 12 clicks, rotated AFM 45*, loosened allen and moved wiper back. The logic behind moving the wiper was to help compensate for the looser spring and to move the AFM (hopefully) to a more 'linear' fuel range that doesn't go so rich. The FPR had to be cranked up in this configuration but it yielded a flat AFR 'curve' from 5k RPM to fuel cut... We weren't sure if the flapper would work this loose on the track though.

 

Pulled from other topic...

Using those exact RPM and length of pull I get 103 lb ft and 114 hp. That's not minor calibration differences.

Are you really seeing peak power at 6800??? We typically reach peak by 6200, plateau to maybe 6600 if we're lucky, then drop at least 3-4 by 6800. It's partly that AFR goes rich up there but even without that ours would run out of breath before then.

We're seeing peak power at +/- 6500 RPM.

 

Most testing has been done with the hood down so that's the first thing we will correct, as all as more closely monitoring engine temps.

 

Thanks all for the input!

[Steve Scheifler]

I'd sure like to know the secret to keeping the AFR reasonably flat above 6500. I think more CQ rotation of the wiper so it think the door is less open would improve that and the idle, and allow a higher FP for better atomization, but it doesn't seem to be a mere "adjustment" issue.

[Steve Scheifler]

Any suggestions on a quick-connect for the fuel test port so I can swap between a pressure gauge and a sample hose? I'm using some out of a fuel test kit which are compact and seemed perfect, then I found that they hold pressure until I wiggle or rotate the connector. Not real helpful. Basic web searches turn up the wrong stuff so I probably just need the right term for it. Not a Schrader valve, but that would be second choice and maybe more reliable.

[Bench Racer]

I have a hard plumbed gauge fixed at the cowl in front of the windshield. Get any engine blips or AFR leans and I can take a quick look at the gauge. Have no data logging devise.

[Jeff Wasilko]

The Iron Canyon is a serious dry-break conector:

 

http://www.ironcanyo...fuel-test-port/

i've got one and it's very nice.

[Johnny D]

What does your pressure gauge have, Shraeder valve?

http://www.advanced-...products_id=124

J~

[RazerX]

i got the parts from mcmaster carr.  dry brake same stuff as other sell just cheaper from the source.  sorry dont have the part numbers handy

[Steve Scheifler]

No, not a Schrader valve. I removed a basic tee with one to install what I have. The IC one is closer to what I had in mind, but not clear whether it is suitable for connecting a gauge directly to it (temporary, in place of the fuel sample hose), and a bit pricey. And without attaching the gauge to the sample hose I would need a second female end for it.
Seems like a simple enough thing.

[Steve Scheifler]

Oh, duh, it just dawned on me why my setup isn't working. Too dumb to admit to the specifics, but pretty sure it will work just fine.

[Todd Green]

If anyone has the Miata Cage kit, this is the female connector part: Eaton FD56-Series-04.  I picked some up from eBay for $6/ea and just hooked an Aeromotive 15633 gauge to it (though I'd imagine any fuel pressure gauge will work.)