I was wondering, how many of you have swithed over from maf to sd. What were your results. Some people seem to favor each system. Which is better for highly modified engines. Is one easier to program than the other. I am planing on putting tpi in my car and I would like to get some of your opinions. It is an 87 maf system. I was considering converting it to sd before I even used it. If I install one of those wiring harnesses it will probably stay with that one for quite a while. Also did anyone experience any performanc increases by just converting to sd. Thanks to anyone who helps me out here. You dont have to answer every question. Anything that you can help with would be great.

Ben

 

How radical is the engine going to be modified? That is the key question.

I have been helping "tune" a buddy's car with a 383, Miniram, AFR 195s with Competion porting and larger 2.05 Intake Valves. For starters, we initially tried just modifying the MAF eprom, well expecting to go SD in the future.

Now, that we have seen the results with MAF, I don't think my buddy is going to convert to SD. Yes, the MAF does max out at around 5,000 rpm, but after that, we just compensate with the %Fuel Add in PE, which is good to fuel compensation to 6,400 rpm; about the max he plans to run the engine.

Yes, the eprom DID need extensive modifications, but he was able to retain the MAF. However, if his cam was larger, then the reversion through the MAF during idle would probably neccesitate a change to SD.

The MAF system apparently can handle a seriously modded engine, though it will require changes to the eprom. Once the MAF is maxed, you must use the PE Enrichment tables to compensate for fuel. But you basically have to do the same thing with SD.

I personally find it easier to tune SD than MAF as I can change a specific Load vs RPM fuel requirement in the VE Table without affecting other things. While with MAF, if you start mucking with the MAF scalar tables, you may change one "flow" area in one of the scalar tables, and it may affect other areas (possibly adversely).

So the bottom line, unless you have a very large cam, you should be okay with MAF.

 

I am planing on running the lt4 hot cam. It is, well I am sure you know what it is. What kind of cam does he run in his 383. I have a friend that I could sell some of my wiring and computer to if I decide to convert to sd. Being as I wont have a stock computer to learn to program the chips on I want to use the easiest system possible. This sounds like it would be sd right? I plan on runing either a 350 or 383 depending on funds. I will be running stock heads that have been well machined to start with, so I will have to run low enough compression for iron heads. I will have headers and high flow exhaust. My friend is doing the heads and the intake and plenum. Hopefully I will get some perfomance heads but that is down the road.

Ben

 

Like glenn said, from everything i've gathered, the MAF scalar tables are black magic voo doo.
Besides that, MAF also requires an expensive and frail MAF sensor.

I'll vote SD for it's simplicity and low cost of all related sensors...

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Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.7 @ 93.6
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

 

personally, i like the maf system myself. due to the fact you can modify a tad more without HAVING to go to a chip change. its all a personal preference though.

 

I can't remember the exact specs of my buddy's cam, but as I recall, it is slightly longer in duration and definitely a higher lift than the LT4 Hot Cam. So you should be okay.

It sounds to me that you currently don't have an ECM (correct me if I'm wrong) so you can go either way. If so, and you don't plan to burn your own eprom, then you could go either way - what do you care if you aren't programming the eprom. If you don't like the thought of replacing an expensive sensor or having a restriction in the intake, go with SD. If those points don't bother you, go with MAF.

If you do plan to burn your own eprom, either will require quite a different eprom than a stock version. Definitely the spark tables on either one, which is really dependent on your choice of heads. Also, for your engine, you will have to compensate for the maxing of the MAF which will happen around 5,000 rpm.

Either way you look at it, the eproms are going to be quite different and require a lot of work. If you are not prepared to do the work yourself, then just get a custom eprom from Ed Wright or Formato.

 

Actually I have the maf computer and sensor and soforth but If I am going to covert to speed density in the long run I would like to do it the first time around. I also do plan on learning to burn my own chips. I have not started building the engine yet. I will do it over time as I have the money but I am just trying to research everything that I can so that I can make as many right decisions as possible the first time around.

 

Do a search on this board and you'll find many answers from previous threads.

MAF is better than SD, but thirdgen SD is better than thirdgen MAF. Its my opinion if you have MAF now, you can keep it until you max it out. If you are starting from scratch, SD is the way to go. There are many MAF guys who have converted to SD, but nobody goes from SD to MAF.

However, since you already have the MAF parts, you might as well keep them and use it.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

 

Yeah, what he said.

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89 RS

STILL Looking For:
An 87 IROC-Z28 350 TPI

Yeah I have an RS, but I want an IROC-Z!!

 

This is completely false. Just a few short years ago, before PROM burning had any real exposure or following (when it was just grumpy and a few other weirdos), i as well as many other on this board had tons of tricks and ways to make anything run w/ anything. I talked a few people through running 350s with stock 305 chips, and it worked surprisingly well.
In today's world, we know that burning chips is now easy, and relatively cheap (best 250 you can spend), and that the stock tuning leaves much to be desired anyway. The fact that you can tune a SD car around every little mod is almost testament to how good it is. Face facts, thirdgen MAFs are very primitive and imperfect as it is, getting them dialed in perfect is very tough, and even then, you're still limited to the resolution of the sensor so it's as far from the ballpark as a SD car with the chip tuned on manifolds running headers.
You know what i mean. MAF has it's uses and works fine. I'm just trying to dissolve this notion that SD is scary and overly sensitive to mods.

------------------
Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.7 @ 93.6
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die