First off its late as hell and I just wanted to make a post about this. My combo I'll outline later but first and foremost can someone host the pictures I have of the dyno graph and the AFR? I have stupid yahoo photo albums and the pictures are a little too small.

For some content: With the AFR nailed at or near 12.5-12.7 the whole way across the board from the starting point of 3200RPM to 6100 RPM I made 240 RWHP and 260 RWTQ with an AFR 195 headed, Stealth Rammed, custom grind cammed, 355 L98 block.

The Torque curve started in the 240's I believe and peaked t 260, then ended just under 200 at 6200. The hp started in the 160's, peaked at 240 and only fell to 225ish maybe 230 by 6200.

Thoughts comments? 38* advance on this tune, 40* netted nothing, 36* ws a little lower numbers. I had them delete that one.

 

What's it run like, is what matters.
The HP errors from dyno to dyno are just ridiculous. Did you pick up HP at the dyno?. IMO, that's all a dyno is good for, ie noting trends.

 

Grump: if dynos are a potential waste of $$$$ do you suggest the GTECH is a better alternative/investment? i need to get a baseline as mechanical changes are forthcoming. see sig. i do not have access to a dragstrip(rural) and stop watch requires another party. i need to work on spark tables as my current sparkis conservative. i think i can get more HP out of my setup.

 

Ohh wow, I forgot to mention my most interesting test of all.

THIS IS FOR ALL 3rd GENNERS EVERYWHERE.


The stock airbox was interesting to test. (The Camaro one with dual filters under it)

On the last pull of the night I decided to do a ****s and giggles test. So I took the stock airbox off and let the MAF run in the open air sucking right straight from the fan in front of it.

The Air fuel ratio which was stuck, NAILED at 12.5-12.8 or whatever, on the previous pull, instantly shot back to 11.9:1 with only the airbox removed.

Thats one trend I noticed. Thoughts on that? Like I said, NO changes other than airbox removal. HP and TQ numbers stayed the same from the previous run, 38* timing etc...

I'm going to the track tomorrow. I'll post up what I ran.

http://f1.pg.photos.yahoo.com/ph/dia...&.dnm=cd16.jpg

http://f1.pg.photos.yahoo.com/ph/dia...&.dnm=9e3f.jpg

There are the graphs, they're hard to read because of the size but you can get the general idea. Thats the best pull of the night. THe black line is the AFR, the Green is TQ, and the Red (on one sheet) and Blue (on the other) are HP. This is all measured at the wheels.

 

I cant get the graphs to show up - yahoo is yelling at me. Email them to me and I'll put them on my website when I get home.

 

Fixed.

Disappointing to say the least Brother Chuck.

One guy mentioned that it looks like my tranny is just slipping... Thats the reason for the flat curve. Thats what he said. I trust his judgement.

 

What size custom grind cam and what compression ratio? The cam might be too small/not enough compression to take advantage of AFR 195s.

 

Cam is 228* 234* .529" .522" 112* LSA

CR is 10.0:1 +/- .1

 

Really no one has any thoughts on why removing the airbox made my AFR go rich?

More air would = leaner. Instead it showed the opposite.

I really want to hear some ideas on this one.

 

When you removed the maf your blms went lean,in turn the ecm added fuel.

THe first thing I suggest is to get rid of the maf system. It's very easy to do, just repin the ecm connectors.

The second thing to fix is the WOT timing. I can tell by your graphs, the s/a is not very well. Your tuner might have just used pe s/a table instead of reworking the main spark table.

The last thing is to not worry about dyno numbers. Rear wheel hp numbers on the dyno IS effected by everything. The worst thing is human error. The dyno operator has to come up with a correction factor. That alone can skew the results. The car can be strapped down wrong. THe tires can be on the rollers wrong. Not to mention countless other things.

I want to see the track numbers. With your mods it should go maybe 12.7 @ 106, if you can hook.....

 

MAF's are very touchy creatures. The ducting in front of it must be there for them to read consistently. The screens are also important to even out the airflow. I'm thinking that without the duct, the air was being pulled in from all sides, and the highest velocity was in the center (picture the air inside the MAF flowing in a trumpet shaped manner, and just outside the MAF it's coming towards it from all directions radially). This increased the signal at the sensor wire, while not being consistent across the duct, thus making the computer think it had more air flow but it didn't.

That's all I can think of as a logical reason.

 

And I would agree. Although I believe turbulance is the factor for reading more air flow.

 

that beast should run out of maf by 3500-4000rpms.It doesn't matter anyways because WOT a/f is not adjustable. Unless..... the blms was above 128 (open maf) then the ecm will add fuel . I would be more conserned why the engine ran out of power early

 

A Gtech doesn't use some make believe imaginary load for the engine to work against. There is no condition in the real world that is even similiar to a dyno run other then wheel spin in high gear, well maybe driving like a fool in the rain, but that's about it. With a GTech you're seeing a true reporting of how the engine reacts to a real load. Most dyno runs are hardly long enough to get out of AE. 3-5 seconds of load is nothing like a 12 sec pass on an engine. Grab a ride in a car with an EGT and you can see how the temps build during a run.

 

Like I've said all along, when you make any changes anywhere in the intake tract it skews the MAF.

You have some very definite elements of engine management design. Mechanical, sensors, and code. All three have to work in conjunction with one another. Changing the air box changes one element and it's reflected in another area. In this case the difference in turbulence changes the way the sensor sees the air flow. Now did the MAF readings change?, if so how much, if you saw the much change in AFR, did you see a similiar percentage in MAF readings?.

 

Are you trying to say the WOT maf readings mean anything? From what I understand, the maf is getting ignored at wot...

 

I know you've had this discussion before, but I'm still of the opinion that it uses the MAF up til it gets maxed out, and then it just uses 255 (or whatever max MAF is for your cal) + PE%, not caring what the TPS is, or anything, just that it's maxed and PE% is thrown on top of the Max value.

If not maxed, then it uses MAF + PE%. So, if MAF was reading incorrectly, the A/F would change. I don't want to start a war, so maybe we can just agree to disagree.

 

There's something wrong with your car. It's that simple. Do a compression test and then a leakdown. I don't know why everyone is talking around the obvious. You are down 80 WHEEL horsepower (maybe more). Something is obviously wrong. This ASSumes that the dyno and wideband were working appropriately. If they weren't then your car could be absolutely fine.

Removing the Airbox on my previous setup when it was pulling 365rwhp only managed to gain 6-7rwhp. This was dyno tested and proven by me. Mike Davis backed up those numbers via testing on his setup. The stock airbox works pretty darn good.

Tim

 

Word

 

The dyno was right, my motor (maybe tranny too) is messed up. Just got back from the track. I ran the same as last year with a 13.9 @ 98mph.

I do wonder now whats wrong. I am pretty sure that its mechanical rather than code related.

 

Unless your running in some default mode, the MAF is used all the time. How is the ecm going to figure out the fuel calculation, without it?. The ecm has to be able to figure out the gm/sec to figure out the LV8 for doing the timing, also.

 

But you need a min TPS to get to PE.
So it does matter what the TPS is, as well as the other sensors, since they all have to be within given windows so as to avoid using default settings.

 

See the effort a GTech would have saved?.
For the moderate HP level cars, they're hard to beat.
With practice, you can do a stop watch one handed, and with care even a data logger can be OK. If you want to use a data logger from a stop, and you have an optical VSS, you can put a LED in line with the ecm with a 1K resistor, and then *stage* until the LED just goes out. That will help eliminate the error of only having 3 pulses per tire revoltion. Or start reading you data log at say 10 MPH and go to 40 MPH. That'll at least give you some data to start noting trends.

And if getting to a track is difficult, the that just raises the need for you to get an ecm bench. Once you get some data you can spend alot of time on the bench looking at the real PWs and figure out what you need to do to make your tuning time as meaningful as possible.

 

Not if it's maxed and it should be with that combo....

 

Of the datalogs I could get to actually open (some of them were corrupted) I found that I was getting to 228g/sec on the MAF.

???? Last year I was at like 25x.xx Nearly maxing it.

THAT is not a tuning issue. Unless those modified MAF tables are still in there... hmm...

 

Not trying to be a stick in the mud but I'm trying to figure out how this thread is related to DIY-PROM? Are you burning chips?

 

Yeah, I was on the dyno and burned my way to 20 extra RWTQ and like 10 RWHP. Thats all could muster after I got the fuel and spark in line. Fuel was at I think 12.7:1 and spark was 38* advance at WOT. The baseline run was the car at 11.1-11.9:1 with 36* advance. So I gained some power but I am still about 100 off hp and TQ.

 

Here is what I have discovered was wrong with my combo, it was a big huge bone headed error and not a tuning issue at all.

I inadvertently didn't hook up my PCV system when I swapped over to the HSR intake. Last year it didn't make that much of a noticible difference but this year with bigger cam, big heads, and everything set up in more of a harmonious combo I found the importance of the PCV system.

I basically hooked up a straight through elbow into my intake tract rather than the PCV valve, which was totally missing in the system. I also had blocked off the port on the TB that the breather style Deutsch valve system was supposed to go to. Immediately thereafter, I discovered why I was getting ridiculously low MAF readings. WOT was 230g/sec with AFR 195's and a Stealth Ram. Now I found the key, I was actually pushing unmetered air into the intake manifold. So, that was my problem. I now need to start tuning again. Because everything up to this point is almost a total wash.

 

how could A cause B.

 

How could sucking crankcase fumes directly into the intake plenum, un metered and non-filtered, effect the motor so much?

I only made 240rwhp on a similar setup to people who have made 100hp more than me, YOU tell me!

There needs to be 350 ci under the pistons, just as there are 350 over the pistons... equilibrium... and I had maybe 10ci under and 350ci over... (relatively of course). The car already feels better even de-tuned with only 36* total advance.

What do you guys think I can run on 93 octane in terms of max spark advance on a 10.0:1 CR motor. Whats the 'average" you have seen. I know the word is give the motor what it wants.... but, whats the average, I'm not gonna run out and do it.