MAF or speed density?
Thread Starter
Intermediate
Joined: Apr 2003
Posts: 25
Likes: 0
From: Granbury texas
MAF or speed density?
Im currently in the process of twin turbocharging my 86 coupe, it still has the stock MAF sensor on it. I was consulting with my local speed shop and the guy there said that it was better to have a speed density sensor(or maybe he said an absolute manifold sensor) anyways what do you guys think. Im wanting to use two HKS BOVs. What kind of modifications would I be talking about? Can you make this conversion? I'm a CNC machinist and mechanical Engineer so Mechanical modifications would be no problem. Also what would I have to do with my ECM? Any help would be appreciated. Thanks
Melting Slicks
Joined: Apr 2001
Posts: 2,105
Likes: 220
From: Ca.
Re: MAF or speed density? (smokin86)
First a very pertinent question....do you have to worry about smog checks???
If not-then I would seriously consider an aftermarket that will run 2 or even 3 br map...what kind of boost levels are you looking for?
If not-then I would seriously consider an aftermarket that will run 2 or even 3 br map...what kind of boost levels are you looking for?
Thread Starter
Intermediate
Joined: Apr 2003
Posts: 25
Likes: 0
From: Granbury texas
Re: MAF or speed density? (drive it)
Well I Live where your cars are supposed to be smog legal, but they never check it. I would have to say though just to be on the safe side that I would like it to run relatively clean just in case they ever decide to. I plan on running in between 14-20psi, this is an all out spec motor and can handle a tremendous amount of power.
Intermediate
Joined: Jan 2003
Posts: 30
Likes: 0
Re: MAF or speed density? (smokin86)
I just changed over to speed density from maf for my '86. Just had motor built, and the guy doing the tuning said that SD. is way more tunable and easier to do mod on. Also, it gets rid of the mass air sensor, which I am told cannot flow enough air for high hp. apps. It was a fairly easy conversion.
Melting Slicks
Joined: Apr 2001
Posts: 2,105
Likes: 220
From: Ca.
Re: MAF or speed density? (30th b-day)
I just changed over to speed density from maf for my '86. Just had motor built, and the guy doing the tuning said that SD. is way more tunable and easier to do mod on. Also, it gets rid of the mass air sensor, which I am told cannot flow enough air for high hp. apps. It was a fairly easy conversion.
If you're going to run twin turbo, then just because of the physical layout of the intake tubing with twin turbo intercooled it would probably be easier to plumb it without the maf-so it would be speed density.
On the basis of not having to worry about smog-an aftermarket would be the way I would go, however they're not cheap. But they can support 3 bar map (which is what you'd need for the higher boost levels), and most of them can run a wideband...which I think would be really nice.
If budget is a major concern; then there are factory ecms that would do the job with repinning and some rewiring. Of course you'll need to tune it also...
Pro
Joined: Feb 2003
Posts: 540
Likes: 1
From: Taunton MA
Re: MAF or speed density? (smokin86)
check ou tthis web site: http://www.ramchargers.com/cgi-bin/n...468&cat2=25469
i know that they have a conversion kit to convert the older grand national maf to the maf off an ls1 which should flow more than enough air. i know that they made this product because the stock maf on the gn's were absolute trash and plus GM discontinued it.
good luck and let us know what you decide to go with
i know that they have a conversion kit to convert the older grand national maf to the maf off an ls1 which should flow more than enough air. i know that they made this product because the stock maf on the gn's were absolute trash and plus GM discontinued it.
good luck and let us know what you decide to go with
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Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Re: MAF or speed density? (comp94)
Have you considered using a 1227749 ECM that was used in the GM Turbocharged trucks? Its a factory ECM that you can repin and use in your car. Reconfigure it for a 8 cylinder engine and you have factory ECM to control your EFI with a 2 bar MAP sensor.
Here is a link for more infomation:
http://www.speedtoys.com/~bort62/7749/Main.htm
Its been done, tried and trued many times over. Now it is not a direct bolt on deal. There are some things like the AIR pump that this ECM does not have provisions for. So if you don't have SMOG checks this won't be a problem. In any case it is not like the device won't exist, as you don't have to remove it. It just will be inoperative and for older cars most smog inspectors just look to see if the device is there.
Here is a link for more infomation:
http://www.speedtoys.com/~bort62/7749/Main.htm
Its been done, tried and trued many times over. Now it is not a direct bolt on deal. There are some things like the AIR pump that this ECM does not have provisions for. So if you don't have SMOG checks this won't be a problem. In any case it is not like the device won't exist, as you don't have to remove it. It just will be inoperative and for older cars most smog inspectors just look to see if the device is there.
