47 replies to this topic

[Sphinx]

So, in talking to Meathead at the MSX show (which was awesome and everyone should attend), he believes (he said he reserves the right not to be truthful, but I believe him ) that a well developed 1.6L is ultimately faster than a 99-00.  Buras (or was it Lamb?) proved that a couple of years ago in a Drago prepped car and recently a Summit Point hot shoe won with a 1.6L.  With that, Meathead renewed my faith in my car.   His words, not mine, were roughly "The 99 is the Ron Popiel of Miatas, just set it and forget it. The 1.6 needs to be constantly fiddled with."

 

I thought it may be worthwhile for us 1.6L guys to collect a list of items that must be optimized in order to maximize the 1.6L.  I'm not including driver skill or motor builds.  I'll assume that the motor is not an issue (a dyno can tell you that) and that the driver has worked on his own skill (a weak area for me).  The idea is the non-routine-maintenance stuff that can cause our cars to perform sub-optimally.

 

Two things I know that I need to work on are:

 

1) an AFM that is data logged and adjusted based on each track to be kept at optimum.

2) fuel pressure regulator - does this actually help or just a nice to have?

 

I'd respectfully ask our ever-present peanut gallery to either contribute usefully to this thead or just observe.  Also, this is not a parity thread.  It should be ideas that actually work based on the current ruleset.

 

Fire away....

[Ron Alan]

For years, the 1.6 could be tuned/manipulated with the AFM. The 1.8 with its MAS did not have that option. When FPR were allowed in all cars to help tune...many use this option now in the 1.6. End result is the same however you approach it....imo

[LarryKing]

What Ron said - if you have a A/F gauge in your cockpit you can monitor the ratio in real time and adjust the FPR for temp/humidity. Smarter minds can correct me but I can't think of a reason to diddle with the AFM once it is optimized if you can adjust the fuel pressure to the same end.

 

As for your basic premise that a 1.6 can still compete (Majors level) I present this anecdotal evidence: I have not seen a 1.6 car enter in a 2014 Majors so far. I wonder why that is?

[Sphinx]

What Ron said - if you have a A/F gauge in your cockpit you can monitor the ratio in real time and adjust the FPR for temp/humidity. Smarter minds can correct me but I can't think of a reason to diddle with the AFM once it is optimized if you can adjust the fuel pressure to the same end.

 

As for your basic premise that a 1.6 can still compete (Majors level) I present this anecdotal evidence: I have not seen a 1.6 car enter in a 2014 Majors so far. I wonder why that is?

 

Just so that we don't make assumptions, what do you mean by once the AFM is optimized?  Do you mean blueprinted (ie: cleaned and made to operate optimally (probably would require being sent out to a shop))? Or do you mean adjusting the clockspring to a certain value/result/dyno tuned?

[LarryKing]

Yes, yes and yes.

[SaulSpeedwell]

1.6s do not have restrictor plates, so they reward finding the highest flowing parts moreso than a 99+.  First, you need a good head.  Once you have a good head, there is a good chance your header and downpipe aren't good enough. 

 

Just because your A/F ratio is "optimal" doesn't mean you have an optimized AFM.  The AFM itself becomes a "restrictor plate" at higher flow.  If you are relying on adjustable fuel pressure or clockspring adjustments only, you are most likely leaving gains on the table.  There are other threads on this.

 

There are a thousand 116HP 1.6s with good A/F ratio.  Every 122HP+ 1.6 I see has "imperfect" A/F ratio, and this is "correct". 

 

Optimizing timing is a misleading red herring gain that wastes a lot of time.  Double-check your BTDC marks, set it to a TRUE 15 degrees, and leave it alone. 

 

Get your throttle plate right so that the car idles where it should, and make sure the idle and WOT stops are doing their job - otherwise, your timing light will trick you, plus you'll fight the engine under braking, and your fail throttle shafts.  Do it once, do it right. 

 

Exhaust tuning seems to matter more on the 1.6. 

 

Fighting "heat soak" matters more on the 1.6.  Trying to keep the engine bay cool and getting cool air to the AFM inlet is worth spending your time and money on.

 

Dynoing with the hood up on a 75 degree day is only good for comparing numbers across the country.  You should be tuning for "on-track" conditions. 

 

+2 ft-lbs is much more important laptime-wise than +2 HP.

 

The data keeps coming back that the fragile 1.6 clutch diff is still "faster" than the 1.8 Torsen unit. 

 

If you swapped ECUs and made power, it is almost certainly because the timing and A/F are different due to tolerances in the ECU hardware.  All ECUs are "equally good" if you reset the timing and A/F.

 

Fuel matters more on a 1.6. 

 

If you run the same % oxygen fuel, the AFM doesn't need fiddled with as much as the apocryphal tales would have you believe. 

 

AFMs installed "flat" tend to change A/F when cornering.  Mod your setup so the connector can point about 45 degrees down.

 

The 1.6 is arguably underbraked.  Use pad compound differences to "optimize" your brake balance. 

 

Remember - you have 120HP if motor but 800HP of brakes.  There is a lot of "laptime" and track position in having the brakes right.

[Bench Racer]

 

I thought it may be worthwhile for us 1.6L guys to collect a list of items that must be optimized in order to maximize the 1.6L.  I'm not including driver skill or motor builds.  I'll assume that the motor is not an issue (a dyno can tell you that) and that the driver has worked on his own skill (a weak area for me).  The idea is the non-routine-maintenance stuff that can cause our cars to perform sub-optimally.

 

 

Two things I know that I need to work on are:

 

1) an AFM that is data logged and adjusted based on each track to be kept at optimum.

2) fuel pressure regulator - does this actually help or just a nice to have?

 

It should be ideas that actually work based on the current ruleset.

 

Fire away....

 

 

 This is a factual positive comment on the Todd Buras 1.6 win at the Road America June Sprints a couple years ago. Todd hung with the top 4 throughout the race and because of a crash and a DQ Todd won the race. The same year at the Road America Runoffs IIRC Todd finished 13th. Todd him self posted that Road America is not favorable for a 1.6. Folks can use single point data to their pleasure.

 

As were all adding to the list of items that must be optimized in order to maximize the 1.6L engine we really need to start at the dyno for the base capabilities of each of our engines. Below is one of Jim Drago's dyno graphs showing some of his numbers for a 1.6, 99 and a 02. When were talking about a 1.6 being capable we need numbers similar to the 1.6 graphed below. This may or may not be Todd's engine. Doesn't matter because different dynos show different numbers. My 1.6 numbers are similar to these with a bit less peak torque and a bit more hp that caries out slightly farther. Remember, different dynos. We can do all the magic stuff away from the engine, but, without engine torque and hp there will be no podiums. We can't expect to podium with 1.6 numbers of 105 torque and 120 hp.

 

I'll accecpt that these dyno type numbers are required for a 1.6 to be competive for a podium and this is my addition to the list.

File 012 is the 02

 

File 024 is the 99

 

File 011 is the 1.6

 

[pat slattery]

In a 1.6 you have to find a way to keep your cornering RPM"s above 5000, if you are around 4500 you will be getting killed off the corner against a 99

 

Plus everything that Saul suggested, is excellent info.

 

Pat

[David S.]

The 1.6 is arguably underbraked.  Use pad compound differences to "optimize" your brake balance. 

 

Remember - you have 120HP if motor but 800HP of brakes.  There is a lot of "laptime" and track position in having the brakes right.

 

What do you mean by underbraked? More rear bias? I'm still pretty new to this and have only done one race weekend in my car. It seemed to  me that the rear brakes locked up sooner than the fronts so I picked up a set of stock replacement pads for the rear (originally had Hawk Blues)  and plan on keeping the Hawk Blues on the front. Good idea?

[pat slattery]

I think Mark is referring to using different compounds on front vs rear.

[Joe (dad) Jordan]

 

 

As for your basic premise that a 1.6 can still compete (Majors level) I present this anecdotal evidence: I have not seen a 1.6 car enter in a 2014 Majors so far. I wonder why that is?

 Just as an FYI  Joey Jordan (my kid) won a SCCA Majors at INDE this year in 2014 and won at Seattle,Portland and the  2013 Western Division Spec Miata Championhip in a 1991 1.6.

 

The biggest things that helped us is car setup and what the others have said above AFM and we saw a widening of the power curve by going to the overbore with the 1.6.

[Bruce Wilson]

The jury is still out as far as I'm concerned.  The 1.6 has been in development in the NW for a long time, so I'm making the assumption that the fastest 1.6 cars still exist here.  Joe, I don't believe there were any top prep 99s at the Seattle or Portland races last year.  A lot of the top 1.6 NW drivers switched to 99s due to the perception that it is the car to have for Laguna, so that will continue to muddy the results.  But Schultz hasn't fared well at any of the Majors in his 1.6.  I think the final test will be the Portland Majors at a track which historically favors 1.6s. 

[Joe (dad) Jordan]

Bruce agreed, but we did beat Skeer and Lee at Inde this year and they are top prep 99's...Ran in the lead pack finished 2nd at Thunderhill a couple of weeks ago... Horses for courses I guess.  RG just said there were no 1.6's at the majors and just wanted to let him know we still run one and are pretty close to the pointy end on some tracks.

[Bruce Wilson]

Not sure about INDE, but not surprised about T-Hill (Good job to Joey btw), where I think the cars are dead equal...  PIR and PR both have long straights and good RPM range for 1.6s, so looking forward to seeing results.  Will be very interesting in Portland where backup 1.6s are just a half hour's drive away!  Hoping I can get into the mix as well, but life just keeps on getting in the way of racing!

[Joe (dad) Jordan]

What Saul speedwell says is very significant ...."The data keeps coming back that the fragile 1.6 clutch diff is still "faster" than the 1.8 Torsen unit"  This is very high maintanence and the mazda comp diff is shard to find parts for.  We may have to switch to the CUSCO unit from Mazda very soon..... 

[SaulSpeedwell]

What Saul speedwell says is very significant ...."The data keeps coming back that the fragile 1.6 clutch diff is still "faster" than the 1.8 Torsen unit"  This is very high maintanence and the mazda comp diff is shard to find parts for.  We may have to switch to the CUSCO unit from Mazda very soon..... 

 

Argh, sorry, I misspoke, but we may be saying the same thing.  The old Comp LSD ITSELF is bulletproof, but the 1.6 ring and pinion that it necessarily goes into is fragile - especially if set up to FSM specs! 

 

Regardless, the Comp LSDs are getting hard to find.

[MPR22]

Top prepped 1.6 with a top driver is a match for just about any top prep 99. As the market moves away from the 1.6 there are less of both out there. It does seem some tracks prefer one car over the other but most seem to be a push.

TWS NASA this weekend was a split decision. One of top 3 fastest 99 in Texas won the Saturday races, short 20 minute races, Sunday one of the few top prep 1.6s wore out the 99s in a 40 minute race.

I am interested in Sauls input on brake compounds for the 1.6, I always felt my 99 could out brake my 1.6 until I changed brake compounds.
Also the Mazda comp LSD has a huge advantage laying down the power in high g turns slow or fast that require a heavy right foot.

Simplest reason for switch to 99s, easier to drive in the good to great range, forgives mistakes, easier to maintain.

However the 1.6 is so much more fun to drive. The smiles per mile favor the 1.6.

[marcusmazza]

Just because your A/F ratio is "optimal" doesn't mean you have an optimized AFM.  The AFM itself becomes a "restrictor plate" at higher flow.  If you are relying on adjustable fuel pressure or clockspring adjustments only, you are most likely leaving gains on the table.  There are other threads on this.

 

There are a thousand 116HP 1.6s with good A/F ratio.  Every 122HP+ 1.6 I see has "imperfect" A/F ratio, and this is "correct". 

 

I assume "good" A/F ratio means running at or around stoich or the 13ish air/fuel ratio line that most dynos display on their graphs. I also assume 'imperfect' A/F ratio to mean running lean. My question is how lean are people running their engines? The leaner I run my engine, the more power I make. I have not seen a sweet spot. Could be because I am too hesitant to run any leaner. My 1.6 has a pretty flat A/F ratio from 3500-6500rpm (slightly leaner at 3800 and 4600rpm). After that, it starts to richen up, which you want in order to avoid melting pistons (my entire engine tuning session from last year is posted in another thread). I have mine tuned, so that the A/F ratio is around 13ish at 6900rpm and 12.7ish around 7100rpm. On the dyno, leaning out from 13 to 13.6 at 6500rpm increased power by close to 1.5HP and torque by close to 1.5ft-lbs. My engine is in the 118HP range and 105ft-lbs of torque. How lean are these 122HP engines running?

 

I found that loosening the flapper door (clockspring) is was worth 1.5HP and 1.0ft-lbs of torque on my engine. I use an adjustable fuel pressure regulator to adjust A/F ratio, because it is easier to adjust and easier to duplicate an adjustment than when adjusting the contact brush in the AFM. I didn't notice much change rotating the board in the AFM. The one thing I haven't played with is rotating the whole AFM. I understand rotating it to get rid of the cornering forces messing up the A/F ratio, but which way should you rotate it. Do you want gravity helping hold the flapper open to reduce the restriction, or do you want gravity helping to hold it shut, which may help idle (not that I care much about how it idles)? May have to try it next time I'm on the dyno.

 

Marc

[SaulSpeedwell]

Top prepped 1.6 with a top driver is a match for just about any top prep 99. As the market moves away from the 1.6 there are less of both out there. It does seem some tracks prefer one car over the other but most seem to be a push.

TWS NASA this weekend was a split decision. One of top 3 fastest 99 in Texas won the Saturday races, short 20 minute races, Sunday one of the few top prep 1.6s wore out the 99s in a 40 minute race.

I am interested in Sauls input on brake compounds for the 1.6, I always felt my 99 could out brake my 1.6 until I changed brake compounds.
Also the Mazda comp LSD has a huge advantage laying down the power in high g turns slow or fast that require a heavy right foot.

Simplest reason for switch to 99s, easier to drive in the good to great range, forgives mistakes, easier to maintain.

However the 1.6 is so much more fun to drive. The smiles per mile favor the 1.6.

 

Re: the brakes, just pretend you have an adjustable prop valve - what would you do? - you are trying to get the car to slow down as quick as possible, and GENERALLY lock the front wheels just before the rears.  I liked Carbotechs because they had so many combinations to try, and in my case I always ended up with 1-2 steps "less" brake pad compound in the rear than the front.

 

But ... at, say, Road America, I was having trouble slowing the car down every lap into Turn 5.  At Mid Ohio, no problems,  I think the 1.6 is just a little below having enough rotor mass and/or cooling as compared to the 99.

[SaulSpeedwell]

I assume "good" A/F ratio means running at or around stoich or the 13ish air/fuel ratio line that most dynos display on their graphs. I also assume 'imperfect' A/F ratio to mean running lean. My question is how lean are people running their engines? The leaner I run my engine, the more power I make. I have not seen a sweet spot. Could be because I am too hesitant to run any leaner. My 1.6 has a pretty flat A/F ratio from 3500-6500rpm (slightly leaner at 3800 and 4600rpm). After that, it starts to richen up, which you want in order to avoid melting pistons (my entire engine tuning session from last year is posted in another thread). I have mine tuned, so that the A/F ratio is around 13ish at 6900rpm and 12.7ish around 7100rpm. On the dyno, leaning out from 13 to 13.6 at 6500rpm increased power by close to 1.5HP and torque by close to 1.5ft-lbs. My engine is in the 118HP range and 105ft-lbs of torque. How lean are these 122HP engines running?

 

I found that loosening the flapper door (clockspring) is was worth 1.5HP and 1.0ft-lbs of torque on my engine. I use an adjustable fuel pressure regulator to adjust A/F ratio, because it is easier to adjust and easier to duplicate an adjustment than when adjusting the contact brush in the AFM. I didn't notice much change rotating the board in the AFM. The one thing I haven't played with is rotating the whole AFM. I understand rotating it to get rid of the cornering forces messing up the A/F ratio, but which way should you rotate it. Do you want gravity helping hold the flapper open to reduce the restriction, or do you want gravity helping to hold it shut, which may help idle (not that I care much about how it idles)? May have to try it next time I'm on the dyno.

 

Marc

 

I'd say assume nothing when it comes to 1.6 dyno tuning, and PARTICULARLY do not assume that flat 13:1 is even "reasonably good".  Some of the only AFMs I've seen that are WORSE than stock run nice and flat at 13:1.  The tuner of those cars and AFMs possibly did not understand that the AFM is:

1.  A "restrictor plate

and

2.  A big determining factor in the spark map!

 

There is no Runoffs or $4 trophy for best A/F ratio.  Your goal is max torque, while retaining as much HP as you can get.  If you tune for max HP, you will be "slower" than if you tune for max torque.

 

Re: rich and lean.  If I had a nickel for every dyno or on-board 02 sensor that bulls**tted me or someone I knew, I'd have at least $150.  Take those A/F readings with a grain of salt, and remember that sensors degrade by reading TOO LEAN.  So are you REALLY too lean?  Looking at spark plugs still has some usefulness here.

 

It is somewhat "normal" for a 122+ 1.6 to get briefly into the 14s in the "lower" (5700? rpm) ranges, and the engine tolerates this well and will not be predetonating unless you are running bonkers timing (>=16 BTDC) - and if you ARE running bonkers timing, you will be predetonating regardless, at least on some days with some fuel.  Keep in mind, you will generally NEVER be at WOT on the racetrack below ... trying to remember now ... 5700 RPM?  Don't take my word for it, but whatever RPM you are at right after you shift.