308 Dyno Runs and AF question

Car is Euro 1985 308GTS QV. Below are printouts of two dyno evaluations. One was in May 2006 with stock engine.

The other two are from today. Am now using the Electromotive XDI for ignition. Advance curves are around 10 initially, 35 @ 3k rpm, and 33 at 8k rpm.

i am curious about the A/F curve. My mechanic, who is very well-versed in Ferraris and the K-Jet, made some adjustments to the K-Jet and felt this curve was good as the car was running a bit richer than this initially. After his adjustment the idle was smoother. Anyway, anyone have a stock 308 AF curve or know about it that can help. Many thanks.
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Well, think i kinda answered my own question in the Supercharger thread. There he says his numbers are:

"AFR at idle runs 14~15.
under load it starts at 14 then dips to 13 and stays there until 4500rpm then dips to 11 at 5500 then climbs again. it looks like i need to advance the timing so we did for another run picked up more power and the AFR pulled up to 12. i have a newer mappable electromotive coming in in a few weeks so i can fine tune again and do more pulls."

Looks like i need to set the advance a bit higher, perhaps to 38 @ 3k rpm??? Do you guys agree?

 

Am I missing something here? I have pulled 177 RWHP with my 2 valve '78 and the highest was 184 two years ago with a 14:1 A/F ratio. All mine had was a modified airbox and ANSA sport exhaust.. My last run was rejetted to 13.2:1

Are these numbers because of different dynos being used? Mine was Winpep. I think graphs can be found in the "airbox restriction" thread.

It's my understanding that a 4 valve should be easily turning over 200 to the rear wheels

 

Different dynos can produce different results. i always used the EXACT SAME DYNO too. The one i used what Verell has called the 'heartbreaker' or some such as it produces the lowest result of them all. Gave Verell a heads up to this thread and he can chime in as he is well-versed on dynos.

BTW: If i went with carbs that would add about 35 to my numbers. Am opting for blower instead this winter.

 

here's how mine is setup. as you can clearly see i need to newer electromitve version to improve the curve. i took the time awhile back to overlay all the mapps and go from there.
Image Unavailable, Please Login

 

Not knocking the horsepower but it's amazing how far cars (in general) have come since the 308 days. The Honda Civic Si, Miata, Saturn Sky and Scion tC all produce about the same numbers... but I guess your results are rear wheel horsepower so you can tag on another 15%.

 

Many thanks, wow! Ok, so you have about 6 at Initial, 30 total advance at 3k rpm and 32 at 8k rpm setting. Nick was pretty set about going -2 at 8k rpm. Hmmm...

 

i never could get the engine to run right by retarding the timing at 8k. so when i overlayed the curves that ferrari set it became clear what was going on. now remember this is for the 2v you have the 4v so the curve is going to be different again.

i had it set at 12 initial with 24 @ 3k and 4 @ 8k so i would get a total of 40* and 36* at 3k. i'm not brave enough to go that high on the SC now. but i do need to readjust the curve above 5k.

 

Amen. New cars have much more sophisticated electronics that are very adaptive plus new cars have variable valve timing, etc. Oh yeah, engines have comes a ways since the 308... as have computers and the ability to make rapid changes for optimization.

 

Wow, that is high and understand what you mean. Maybe i should take the 8k setting on my QV and move it from -2 to 0 just to see how she does due to my now known A/F situation? Your thoughts? ALL help is ALWAYS appreciated!

Wish i could have done this on the dyno BUT they were kind enough to give me good dyno time and make the K-Jet adjustments. Did not want to overstay my welcome as it were.

 

i'll see if i can dig up a 4v timing curve. but you are running way to rich for NA and that is costing you HP. how's your fuel consumption? i'd get a temp gun and measure temps across the headers and plug wells to see if they are even and as you increase timing see how how much they gain in temp. good thing i bought 3 off peter i've already lost one .

give me few min and i'll have a graph for you...

 

Got it, it is below. This is why i was hoping someone had the AF curve. Agree she is rich... but better to be too rich than too lean.

High, but i like rpm and track the car so...

Yup, agreed.

Got one off Peter too Will do that shortly, and at latest when i am at the track on Oct 19th as will have open track with actual track time of about 4 hours, not the usual 100 minutes in a day
Image Unavailable, Please Login

 

okay a quick check shows the US 4v with 6* @ 1k and 32*~33* total @5k with no vacuum or advance so that would be the retarded timing. the vacuum advance will advance the 5k from between 32*~40* and there is a spike at 4k dependent upon load. i'm working on graph....

caught the post...thanks

 

alright, here we go.
i'd set the intial at about 10* run the 3k at 22* for a total of 32* and then advance the 8k to 2*~4* it'll put you alot closer to stock and with your shorting the shifts to 7k you'll only get to around a total of 33*~34* and that's still below stock.

keep us updated..

 

Will do. Am going to buy a A/F meter from Summit Racing this evening and wire that in as well. MANY thanks for all your help and patience. MUCH appreciated.

 

I think it must be a difference in the dynos. A couple of years ago my all stock '82 Euro GTS QV pulled 183 RWHP/150 ft-lb torque on that same dyno. My mixture started very rich & it was hand tweaked 3 times for 3 pulls. The hp went up 2-3 hp with each tweak. Because it was a group dyno day, there wasn't time to hook up the A/F meter & try for optimum tuning. However, the car had noticable more pep after the tweaking. So Steven is closing in on me.

However, a well tuned early carb'd 2V shouldn't be that much different from a Euro QV. The QV was primarily intended to get back the HP that later Carb'd cars & the injected 2Vs gave up to meet emissions.

The results on this dyno are very consistent (within a few hp) over long periods of time. For example, Steven's car was tested that dyno day & I believe that his results back then were pretty close to the numbers he got on 05-06-06.

The Dyno Dynamics dyno is supposed to be calibrated so that it adjusts for each days atmospheric pressure & temperature so that it's readings always match the SAE spec'd test conditions. The company has an operator training program that certifies that results will be consistent when run on their dynos in different locations, altitudes, etc. I've heard Dyno Dynamics referred to as 'heartbreaker' dynos because their runs are generally lower than other dynos being used in this area.

I've been under the impression that the K-Jets did a much better job of keeping the A/F ratio consistent. However, the Euros only had the basic mechanical K-jet w/o lambda feedback. Am very interested in seeing how the proposed timing tweaks change Steven's HP, torque & A/F ratio.

 

Steven,
Make sure you get a 'wide-band' A/F meter. The narrow band ones won't give you the data you're going to need.

A while ago someone posted links to what looked like a pretty good wide-band unit in Tech Q&A. Good chance that Summit carrys it. Search for 'wide-band' & 'A/F' etc.

Don't get a narrow-band unit like the $100 Edelbrock that Summit carries, much less the $50 panel mount gauges & LED bar graphs. They just use the standard car O2 sensors whose response curve is almost a step function around stochimetric. A wide band sensor alone goes for around $100.

Took a quick look at Summit. The Innovate, COMP cams & UEGO type look reasonable, but I haven't researched any of these in depth.

I like the Innovate INN-3723 & LM-1 because they provides USB data logging & PC software.

 

Hi Verell & Steve, I have the LM-1(purchased from Pegasus Racing) very nice instrament to use. You are able to monitor and store A/F info(up to 40 min.) and also down load onto a PC, there is even and adaptor for monitoring rpm and other computer sensors. The LM-1 is like a fancy VOM with storage capability. If you have a non cat car can buy the adaptor to set the O2 sensor in the exhaust pipe. I opted to weld 02 bungs near my factory 02s on my 355 and on my 749 Duc and F4 MV motorcyles. The bikes have adustable CO mechanisms just as a point of interest the bikes seem to like 13:1 or there abouts. For the 355 I use it for monitoring to make sure the computers are doin' there thing correctly. I would go along with you on the fact that you need to use nothing but the wideband 02 sensor technology, much more accurate. Regards, Vern

 

I run mine a little more agressive than that.

14 at 1000
25 at 1500
32 at 3000 and above.

Getting the timing in early makes the engine a lot snapping down low. Up top, optimal seems to be in the 32-34 range depending on the engine. You could replace the 32 at 3000 with 34 at 3500. Only the dyno will tell you what the right number is for your engine.

The AF under full load should be 13.2 at all rpm for peak hp. Many people like to run just a tad richer, may as low as 12.5, but no lower, to keep the engine cooler. Some newer cars with very high compression rarios (360) run something like 11-11.5 so it doesn't detonate with all that compression, but that's not your situation, the QVs are claimed to be 8.6:1, but are actualy under 8:1....perfect for adding boost

 

I forgot, the AF meter. I personally think it would be a waste of money for you becasue I don't really see you using the data to take any action. On a crab car, it's a must have because jets change with the weather. But on an injected car, that problem has been solve, you set the mixture on the dyno and forget it. They are very handy on an EFI car with a programable ECU for inital tuning...but they are also built in to most of them, so even if you go that route, you won't need the stand-alone unit. Save you money, you already have your AF curve off the dyno.

 

Man I love threads like this! I'm sitting here like a sponge just soaking up knowledge from the gurus! What better thing to do when you have dad-duty and you have a 2 month old asleep on your shoulder? (The little guy is snoring. Is that cute or what?)

Birdman

 

Darn, already ordered the basic unit SUM-G2986. ARGH! Will see if i can cancel the order. Just called them, they already shipped it. DOH! Well, guess i can refuse the shipment according to Summit's phone rep.

Verell, looking at your Dyno sheet i have here from 2 years ago and mine, seems i have about 10 more TQ but about 4 less HP. Also noticed my 308 makes more TQ early on than you, yet your HP curve goes further up than mine. Hmm...

VERN, many thanks and yes, already have a welded in bung on the exhaust for an O2 sensor. On the dyno they used the bung with their known good O2 sensor. Appreciate the lead concerning a wideband sensor.

 

mark,
the electromotive xdi has three points for adjustment.
initial~1krpm
3krpm
8krpm

its additive from the previous, initial is from cranking to 1k then it climbs to the 3k setting plus initial and from 3k it will advance or retard based upon the 8k setting. so as you can see it's really 3 lines of a curve. i found that overlaying it on the stock curve you could get a good compromise.

for his track use a AFR wideband would be good info, all the data you can get in my opinion is good. helps track down problems faster. i'd get as agressive as possible with the timing but as a safety measure do it on the dyno so you can see whats going on. steves concern is long term reliability so he keeps the shifts under 7k, so he'd need to tune for 4~7k and for that i'd suggest finding a mustang dynamometer as you can dyno tune at fixed rpms.

the CIS is a great FI system for its day and can be adjusted as needed provided you know what you are doing. there are regulators out there that have some adjustability to them that allows for tuning in these types of cases. also the regulator that ferrari used on the 308's is the big daddy of them all in that is has vacuum/boost and atmospheric adjustments already built into it. most are just vacuum, some have the atmospheric and the rare ones have all three.

steve, i'd talk to larryS on the board here about the rich issue, you may have a fuel distributor that needs rebuilding. that AFR reading is just too rich and the way it falls doesn't seem right. it should be level at some point.

it's really cool to see these cars still in action on the track, keep it up steve!

 

Thanks for the clarification

 

If those are the only choices, I'd bump the 1000 timing to at 15, that will help and he's stuck with the rest I guess.

I guess my outlook has always been that track time is a lot more expensive than dyno time, so I've always done my engine tuning before I get the the track. It's certainly not wrong to have more info, but engine tuning chews up a lot of time with into the pits, adjust, run a lap, back in....better to have it all done. To me, an AF gage on an FI engine is even less useful than a vacuum/boost gage, you use it setting up the engine then never look at it again unless the engine is broken.

Most of the dynos out there these days are equipped with an eddy current brake for constant rpm tuning. It definately does make somethings easier, I do all the base tuning that way. But the acceleration dyno runs are very helpful too, they are extremely repeatable between dynos 9of the same brand) and there are a lot of little things that only seem to show up as transients. So after the base tuning is done with the brake dyno, I switch to acceleration to fine tune in 4th, then confirm everything in every gear...the low gears tend to like it just a touch different than the high gears (more timing, more fuel), so comprimise comes in here.