One of my friends, actually Todd, a forum member, is looking to replace his carb with a fuel injection setup on his 86 IROC. The car is a 350 L98 block with a hot cam, trick flow heads, and long tube headers. Ultimately he would like to go with something like a Stealth Ram (we can get those cheap because of contacts at Holley) or a converted LT1 intake, or something. What he needs currently though is a wiring harness, computer, and any intake just to make it run in the short term.

What we're looking at is the possibility of picking up a used TPI system and just putting it on the car to get it running. We're willing to sacrifice top end power in the short term just so we can get the car up and running with fuel injection. Swapping the intake later would just be a matter of tuning it again which isn't a big deal.

So, in looking for a proper TPI setup, he has some criteria. He is looking for a speed density setup rather than a MAF. What he's curious about and not sure, can you run a speed density with a speed density computer, and a MAF harness? IE, does the MAF harness still have a MAP provision, and is it reasonably easy to make work if you just eliminate the MAF connection or does it require rewiring the entire harness?

 

DOH! Could somebody move this to C4 Tech where it belongs

 

It is not easy to convert a speed density to maf or vise-versa. Buy the one that you will stick with. My .02 is to stay away from speed density. Too finicky. My maf car still has stock programming and has great driveability without being dependant on a chip burner for every change. I am referring to the 85-89 maf arrangement. I have no experience with the later year stuff.

 

I agree, i really wonder why so many cars have a speed density setup in the first place, and why they do not have a MAP sensor to control the timing and with a MAF to control fuel.

Some of the European cars we work on are really just 2 six cylinders sharing a common crankcase, this works out good.

 

Well his chip tuning is free because I'll be doing it. I know there are some benefits to a MAF but there are some major drawbacks as well. One of which being that he would have to buy the MAF, obtain all the MAF burnoff relays, etc, etc. The cost of making all that work can quickly outweigh the cost of a pure speed density setup.

There is also an upper limit on what the MAF sensors from the TPI cars can read. My friend is a tech at Saturn and knows for a fact that some of their 4 cyl cars can and do flow more air than the TPI MAF is capable of reading, he has no problem believing that his modified V8 can as well. I know there are ways around it, because plenty of people make big power with the stock MAF on these cars, but it's a complication he just doesn't really want.

FWIW, his combination is straightforward enough that tuning it on speed density won't be hard.

 

I think that is why some, or all of the V12's have 2 MAF's.

I just always thought it was neat how they made them work together as one unit with to ECM's.

 

That would be pretty neat to see!

It's amazing what people who are smarter than me can do.

We may have a line on a complete speed density setup, harness and all for a reasonable price. We were just gonna see if there was any chance at using the harness that he already had but it sounds like that's a pain.

 

Some other considerations on an '86 Camaro is whether it has a serpentine pulley setup or multi v-belts with a mechanical fan. It's hard to route the induction plumbing for MAF so it clears the fan. Also, the water neck for the thermostat points forward for the upper radiator hose on a TPI manifold. A mechanical fan wouldn't work with this neck unless you cut it and rotate in 90 degrees then re-weld it. Most serpentine systems like the later TPIs had electric fans mounted to the radiator so there were no interference problems. Also, serpentine systems utilize a reverse rotation fan as opposed to multi v-belt setups. You wouldn't have this problem with a MAP system since you wouldn't need the MAF plumbing and filter and you could run the multi v-belt system. The only thing you might have to do is change the thermostat neck.

Art

 

Firstly, the 86 came with an electric fan and V groove pulleys, so did the 85 and TPI was offered in both years (MAF) so fitting it all in there is a no brainer.
Next, the max measured flow rate of the early MAF's was 255 gms/sec. To max that out on an N/A engine isn't impossible but you'd be putting down some VERY serious HP. The true problem isn't with the MAF itself, it is with the code used in programming the ECM, the MAF itself should, in theory ,be able to measure any amount flowing through it, but the ECM just can't read that high.
If you friend is dead set on speed density I would not fool with getting a MAF harness and converting it. To do that you'd need to go one of two routes, either repin the MAF connector for a MAP sensor and use the Aussy 808 code (limited to 160 baud connect rate) or repin the connector and then make a set of harness adaptors for the ECM connections. The 165/870 (MAF) ECM's don't use the same connectors as the 730 (MAP) ECM. and going the route of doing that to a used harness, You'd first want the engine up and running with that harness as it was intended to be (with a MAF and correct ECM) before you go cutting and repinning. This is to eliminate the possibility that the harness is bad before doing the conversion.
The easiest route to go speed density is to start with a speed density harness and ECM to begin with.

 

The car started out life as an 86 IROC but there is nothing much left stock under the hood. Even putting a "factory" fuel injection system back on the car is going to be a hassle.

The question was asked simply because he already had a MAF harness but does not want to run MAF. We thought if it was possible to save a few bucks that it might be worth it, if it was a plug in. Since it apparently is not, we'll just look into complete SD systems with the harness included.