Ski,

Thats great testing you're doing !!! You're a tried and true hot rodder !!

It is strange, I would have bet a shiny nickel that you picked up a tenth or two with your rpm happy 434 getting rid of the itty bitty tiny MAF !!!.... glad I didn't.

Can't wait to hear the results with the MAF back on.... that will complete your A-B-A testing and tell us everything. If it doesn't find your missing et... my bet is on the tranny slipping and/or converter problems.

cheers,
Beach Bum

 

Raman.

I completely removed the ducting and just ran the open thottle body. I opened up my air box (no air cleaner) to allow the cold air to enter the engine compartment which flowed air directly at the WOT Throttle body so I feel there was adequate cold air.

As I mentioned above, I thought that perhaps the air turbulance was causing a problem, so I added back in the air tube with the MAF( for a run) then took it back out. The Car ran dead nuts the same. So I concluded 2 things. 1. TUrbulance from there being no air duct didn't matter, and 2 putting the MAF back in did not effect the ET. The second is sorta a no brainer when you think about the ET I ran before, and the fact Corky is running it down to 10.5s.

I am as guilty as the next person as to "thinking" about things that "should" make the car faster. I find myself in my garage staring at the car ( I know, obsessed as my wife puts it) trying to find the thing that should make it go faster. BUt all too often the things we "think" should improve performance really do very little. THAT is why marketing guys take such advantage of unknowing customers, like with the tornado. I like to think the things we do are a little more sensable then them, but you get the jist of what I am saying. Sometimes things we think will make us faster, end up hurting us.

These setups are VERY complex and I like to say "Living" they are not as easy as we think to figure out. MANY factors influence the way things work together. THAT is why the guys that can make a 350 CI motor make 800hp are worth their weight in gold in the performance world.

I agree Beach the A-B-A test is the tell all......My part I need is not going to be here till Monday so I might have to wait till next weekend to conclude this saga.

 

Hey Jesse, maybe the key to making improvements with a SD system is going to an aftermarked setup like Accel DFI. Their computer is probably not worried about emissions and such. I know you were trying to make the most of the GM computers, but maybe you have reached their limits and to go faster a different computer setup is needed. I agree with your inital assumption that the SD setup should make more power but maybe not with the GM SD computers.

 

well I certainly am dumbfounded.
I would have thought the SD would do better.
(I was just thinking about changing to SD the other day)

only thing I can think of to try would be to add more AE and see if it helps.
purhapes SD calculates AE differently than a MAF system.
I suggest trying it because I think AE kicks in during shifts even at WOT (based on load change), but I could be wrong.

it sure doesn't make sense though, at the very least I'd expect it to run about the same times as a MAF.

thanks for sharing your findings ski,
think I'll stick with the 165ecm now.
RJ

 

I just switched from a maf to a fast system with a wide band on my 434 and with no other changes i picked up almost 2 tenths with my car. Keep in mind i still have the maf in place just not pluged in. I tryed some testing also like removing the maf and just running thru the T.B and my car slowed down with back to back runs. My 60' times didn't change and now i'm hitting 103 mph in the 1/8 but my mph in the 1/4 hasn't change much. Next time out I'm going to try and get a better 60' time hopefully without breaking something and see if i can get into the 10.60's.

 

If I may just step in and say...Don't all the Turbo Buick guys still use the MAF system? Only don't they have a "MAF Translator" to compensate for big boost.

 

Chriswtx/thetoy,

You guys are reading my mind. I made the same exact comment to Corky over the phone early last night. I believe this is why some people might gain over the SD system or GM setups. Expecially if things are not fully optimized in the SD/MAF setup.

I woke this morning again thinking about this topic. Here is another very valid point to show that the "displayed" timing may not be the "actual" timing the motor is seeing. Think about when you get knock retard from the knock sensor. The main timing displayed does not change when this occures, and the only reason you know timing is pulled is the fact that the retard timing is displayed. Well there are no idications for other spark adjustments. And I KNOW there are other compensators, but I honestly do not know what triggers them.

Damn this really has me baffled and starting to seriously doubt what is happening out under the hood. I am seriously starting to think that the 870 computer might be the ticket around all this mess.....

When I open a $1f bin (870ECM) there are only about 10 parameters that can be changed compared to the 50+ that the 730 ECM has. Only makes sense to think the 870 is a simplier, more passive system that will just do what its told and not intervene with its only corrections... Not to mention a buttload less money than a DFI system....

 

Ski,

My very first thought at the beginning of this thread was... what kind of ECU are you using. I have a FAST box and wouldn't even think about trying to tweak a stock GM ECU for SD in a high perf. application. Get yourself an aftermarket ECU and THEN go test. Make sure you get the wide band option. I think you will find the ETs you are seeking...

 

I have done a similiar test with my car. It is a Road Race car so the results are not as conclusive as yours because of many other variables on a 2.5 mile track., but basically when I switched I neted about the same lap times. No slower no faster. I feel the map pulls slightly better at higher rpm and the maf seems to have better pull up off the corner, resulting in similar lap times.

Jesse the other thing to try is the 808 mod (I think that is what it is called).
You can use the 165 computer and just move the maf wire on the ecm to a diff pin and that goes to the map. then the map just need power and ground. It to also has limited parameters to deal with and no emissions. The only problem is it is in metric so it is a matter of getting used to the translations.


Chuck MacTrinder
www.tccracing.com :flag

 

Sorry to hear about your bad experience SKI,
Does not really make any sense to me, if you match the Inj PW for RPM incriments, and timing is the same, how could it be different?
I was wondering if you increased the size of tube from air diverter to TB?

Another thing to try is Phsically check timing VS. what prom is set @ on both systems.. Could find some difference there.

Either way you and cork have proven MAF to work exceptional under given conditions even with a large cube engine.

 

The fact that Tims (TheToy) is running very well is a very good indicator that a SD controlled engine can run faster than a MAF controlled scenario. It could very well be some other limiting factor within the GM controller that we are not seeing with the present tools we have to edit the tables. There could be several tables or limits that have not been found in the 1227727 ECM or other later SD ECMs. But that day may come to an end very soon

Oh and Tims car is running those numbers on a base tune that I did for him when I first programmed his FAST system. I know for a fact that his FAST controller is PIG rich in fuel maps as I have not had a chance to "fine" tune his system yet So I feel pretty confident that theres more to be gained in his car, plus he is still sucking through that MAF that is still in the intact tract!

 

Jesse,

You've gotta' know there's another problem somewhere!
Remember that the SD chip you did for me went 10.03 @ 133.2 and I've got a lot less engine than you do. Keep on plugging away at it, you'll find it, go back to basics and start checking everything.

Good luck, Dave

 

Dave...

I have been over this thing 10x now and can't uncover anything...I have made just about every excuse there is to give it one more shot.

I think the A-B-A test with the MAF system going back in will tell all.

On your car which runs exceptionally good, remember you have MANY advantages...

1. T350 tranny,
2. Solid Axle Rear you said you went from 11.0 to 10.6s with that change
3. Big old Tires
4. Gears
5. and I believe a lighter setup, the one day you thought you were about 400 pounds lighter. Which would make a huge difference. Not to mention the weather we are in now is not nearly as good as when you ran down at Mason or Cecil that one time.

I can do some more diggin on the car, but don' really expect to find anything.

87_TA and TJ,

I firmly believe that the timing is changing via the ECM, and no report of its kicking out. 87, your 406 setup I think would have run right with ours last year, perhaps you where/are experiencing the same thing. As your about the same exact margin off what our 406s would run. The one day out was the only time you nearly hit my times, and EVERYONE gained about .2sec that day due to the DA, and I recall you picked up 1.6sec. I remember that conversation over on the other board, cause I said you probably lost some ET when you said you gained from a change, and everyone Rich@keystone ran ~.2sec quicker, Beach ran a super good time out in Ohio, and several other reported great times from Keystone. I was a rare occasion when we inlanders got some E-town DAs. lol

TIme will tell. I wanted to do the testing today out in Ohio, but the adapter I need to convert back my stock memcal is not here. Next weekend.

 

There was great weather that day SKI,
My car trapped almost 126 that day but 60 was not there.
This year I have hit teens and 20's , My 30's and 40's Were results of traction problems that I still have.
Toward end of day I hit 11.100 with a horrible 1.65 60 ft. spinning.
I also lost converter lock up this year and went to a larger Tire hurting my gear in an attemt to hook.
Also if you remember last year when I figured out my converter problem locking to soon , that day I ran a 11.18 then the next ran the 11.0 which was last day of season that I could make it.
If I can get a solid hook with my smaller 26" tires and get converter to lock again I should be back to the 11.0's, and better on good days.
I just recently tried to slow the car to 11.5's to not be kicked off track again. I had to drop timing to 20 degrees total up to 4200 and 25 degrees there after as well as put on my restrictive air intake tubing and still ran 11.46 @ 2200 da.
Then went back for street wars @ 3100 da and ran 11.54 with same setup, dropped timing 18* degrees from where it was along with restrictor and still hit a 40.

 

Just trying to get my head around the issues here… but if you rule out the MAF as an air flow restriction. Why would either the SD or MAF system be any faster. Both are capable of supplying the same amount of air, fuel and timing and can be set up to sense load at WOT. I would think that the real difference would be in part throttle or off idle driving where the SD system might have the edge by using vacuum (virtually instantaneous) to sense load vice the millisecond longer it takes for the air to be drawn past the MAF. Am I way off base here?

Jim

 

IRC,
I think the main issue that Ski has is the SD computer interjects controls on motor that cannot be tuned out. When he disonnected the computer the car went quite a bit faster.

Excuse my plain english, I am not as knowledgeble as many here, but I was at the track when he disconnected the computer and his car picked up bigtime.

 

That is precisely correct what Jim just stated.

My belief is that the ECM itself, trying to control emissions or trying to "optimize in the sense of emissions" is toying with the timing and Fuel ( Not so much the fuel as I would see that on the logs from the WB02 output) but the timing.

I don't know how else to explain it, other than I firmly believe that what I put into the program as far as timing, is not getting sent to the motor. And the fact that its not constantly the same, I can't tune it out. It may only be for small portion of the track, when its triggered -but it utimately results in lost ET.

I put the MAF back on the car last night and it ran great. To be 100% honest with you, and again its just my opinion, I think the throttle response is even better with the MAF. But it might have been just my head playin games with me, since I have not driven the car in a few days. Actually a week, since I left the slicks on it, hoping to make it out this past week. But when that did not happen I changed over the tires.

But in the nutshell that is my theory on what is happening. That might be why Corky's car might have the edge on even my 165 ECM. Its older and can't screw with as much. It runs what its told, and doesn't care what happens outside those parameter. Which ultimately is exactly what you want in a drag car. Things changing run to run, result in nothing but first round losses. That might be why also guys see gains from the DFI conversion. Even for me though, .2sec is a mere gain for 3000 dollars. I would put nitrous on it before spending that sorta cash. Tell me I would be pushing 9s with DFI, I would do it, but I don't see that happening without some serious improvements on the 60' times - to the tune of 1.3X 60' times.

 

Jesse, I have two old 6.32 DFI systems I'm going to sell... You're welcome to give one a try. They're easy to program and with a WB logger you won't have any problems. I would wager you'll gain with it. My '90 ran the SD computer up until I decided (about 8 years ago) to put the DFI on it; I gained considerably over the OEM system. Albeit I have had a lot of radical engine combination that I simply don't believe work to their ideal with a stock ECM.

FWIW: I'm running a FAST system now and the new SB2 mill will be tuned in Alpha N mode instead of SD; using the TPS to determine load instead of the MAP... Reasoning? Mucho camshaft duration and lift throw MAP sensors into hystrionics; perhaps that may have been a problem you had.
-Jeb

 

Jeb,

What all is entailed in putting the systems in?

Its is a drop in and not much required I may entertain the install for a quick testing to throw DFI into the mix.

Send me an IM with the details of the system. I am very hesitant to start another project that will consume the rest of the season....but what the hell.

 

Unless you wanted to splice into your stock wiring harness which I don't think you want to do for a test, the easiest way is with a piggyback harness. The only problem that you'll find is that the harness is somewhat cost prohibitive for "testing" purposes.

Let's say that you borrow Jeb's 6.32 DFI system and get a harness for it, and it works out for you. You'll either have to stick with the 6.32 unit or get a new harness for the DFI7 or FAST. (the 6.32 and DFI7 harnesses may be interchangeable, but definitely not so if you went with a FAST).

Ron