I posted this in the TPI board also.

I'm planning to go FI from Carb on my 84 TA but was wondering, what is the better system and which way should I go? Intake will most likely be a TPiS miniram in preparation for a 400sbc.

Can I get some input as to the pros/cons of the MAF vs Speed density? Basically, which is preferred or better and why?

Any insight would be greatly appreciated!

 

I like the tuneability with maf. In my experience its been easier and quicker to get tune good enough but the big motors start maxing out the stock maf early and could pose a restriction on higher hp builds. That said i did not find a restriction at the 400 whp level with gutted stock tpi maf intake vs custom 3.5" maf and cold air piping.

Speed density 7730 ecm has more control features. Higher rpm tables for fueling. Dont have to rely on pe mode enrich vs rpm as much but thats not a bad thing. Just different way to get the fuel in there.

Either method is good. Speed density may have abit more flexibility in programming since its a larger memory chip, hence more detailed control features. Close loop activated by rpm can be helpful for big cams.

 

If your engine is near stock or doesn't have a big cam then MAF is probably easier to tune. If you have a big cam then reversion can upset the air-flow meter and give the wrong fuelling. Speed density which works off of manifold pressure can cope with big cams better and some say has better throttle response.

 

Eventually, the system will be exported to my next engine build which will be a 400sbc. Now that may be next year, or two years from now, just depends on how much of my money the wife spends between now and then!

 

If you are even contemplating a 400 with a cam I'd go SD personally. Make sure you get a fuel pump and injectors big enough for your next build.

I have a speed density system on my TA with a 400 which has a reasonably big cam. My C5 has both and I've tried the standard, which is a mixture of both, MAF only and SD only. SD does seem to have slightly better throttle response but there isn't a lot in it really.

 

Cool, thanks. That seems to be the consensus for a bigger cammed motor.

 

I always felt my maf 383 had best throttle response than speed density motors i had which have been my turbo 400's, a stock 91 305 tpi and a ls1 trans am. Trans am was good tho. I guess its all in the tune

 

N/A, see next post.

 

Well, what MAF should I get then for a 400 since you said the factory MAF was maxed out? Any links to one you'd suggest?

 

It maxes the reading quickly but still can control fuel via pe mode enrichment for wot

Either system will work. Its probably best to go speed density because finding good mafs probably getting difficult

 

There are higher flowing MAFs for the C5 Corvette you could look into. They come in sizes 75 - 100 mm.

 

.....you could do the TPI with the LS1 electronics, just a thought

 

How so?

 

And they'll fit using a TPIS Miniram?

 

EFI Connection's 24x system.

 

This is an old argument, but it's still interesting to read some of the different preferences by users. I'm running an EBL-P4 which is Speed Density based, and within a matter of five minutes taking my time I could have any carbed SBC/BBC up and running with any set of injectors of my choosing, including E85 fueling. It's just too easy to do. The EBL-P4 was just given full alky control too (see below) in conjunction with its' existing boost control. A MAF only system is a complete waste of time, don't even consider it. A MAF w/Speed Density system holds not real tuning advantage over sole Speed Density, save for maybe a tuning correction at idle during dense changes in weather, but the EBL-P4 has its' own VE Learning ability, so no real issue for our users there. Plus in this hobby, the big boys don't mess with Mass Air Flow anymore, that was only when there were no other options. Revisiting some of the older pro's vs con's wouldn't be accurate anymore, because a lot has changed...