Speed Density-> Yes or no?

ewingr · 12-15-2006, 07:43 AM

I am putting an '04 Corvette LS1 into my '56 Chevy. I purchased a 0 mile engine on a pallat. It did not come with a MAF.

It has been suggested to me to not get one, and run speed density. But in a very short email conversation (which I may pick back up with him) the guy that I had planned to have my computer programmed by said "I don't support speed density". I haven't had any other conversations with him on it.

So, I thought I'd ask here. Is it a good idea? Bad?

I plan to just drive the car to rod runs, and cruise around. I want it to be streetable/drivable, and don't plan to race it. I of course love having HP, but my interest now is drivability, gas mileage, and no hassles.

What are your thoughts?

**Pythias** · 12-15-2006, 09:07 AM

Originally Posted by ewingr

I am putting an '04 Corvette LS1 into my '56 Chevy. I purchased a 0 mile engine on a pallat. It did not come with a MAF.

It has been suggested to me to not get one, and run speed density. But in a very short email conversation (which I may pick back up with him) the guy that I had planned to have my computer programmed by said "I don't support speed density". I haven't had any other conversations with him on it.

So, I thought I'd ask here. Is it a good idea? Bad?

I plan to just drive the car to rod runs, and cruise around. I want it to be streetable/drivable, and don't plan to race it. I of course love having HP, but my interest now is drivability, gas mileage, and no hassles.

What are your thoughts?

Speed Density would be fine then, but doesn't that engine come stock with a MAF? I would be weary of changing something like that, last time I remember speed density being used was on an 88 5.0 Mustang, not sure about chevy's. If that engine comes stock with MAF, I'd go with that, changin to speed density may cause some problems...

**Doc99SS** · 12-15-2006, 10:05 AM

You want to run MAF sensor with that engine and a MAP (speed density)sensor. Were you planning on getting a stock '04 PCM and wiring to go along with that LS1 engine? These engines run on a PCM that looks at MAF & MAP.

BTW: for the best overall drivibility that will adjust to changing atmospheric conditions, you want to run a MAF sensor.

**12secSS** · 12-15-2006, 02:03 PM

Both will accomplish your goals, just with a radical cam or serious boost is where the MAF would not be viable anymore. For a stock engine up to a mild heads/cam setup, I always do a MAF tune. Unless of course the customer request a purely SD or Open Loop tune. Both will compensate for altitude and/or weather conditions. I have tested this out numerous times, with the MAF enabled and disable (Speed Density), my fueling stayed with 4% of the targeted AFR (verified by my AEM wideband). This was done going from our SoCal beaches and within two hours being at over 4000' in the SoCal mountains.

**tblu92** · 12-19-2006, 10:31 AM

On a street application or even a modded car with mods up to heads and cam-My experience is to always use the MAF system.Speed Density should be reserved for radical combinations-Also on a basic street type car say up to 4-500 RWHP speed density tuning is very time comsuming and for what ?? a 5 HP gain ?? To me it's not worth the effort. It is still good to work on the VE table as when you are over 4000 RPM the comp uses a combination of your tune and the VE table to set the fueling.Especially around the transitional area between 3600 and 4200 RPM.It will just make the transition much smoother.Everone uses different methods-I use a combination of all 3 of the basic files to set PT fueling and PE or WOT fueling. The MAF table---the IFR table and the PE vs. RPM table.You can get it darn near perfect using these and it will run smooth and idle well.I use the narrowband 02's as a starting reference point to set the WOT AFR but you should always check it with a wide-band 02 to make sure its ON. Just because you command a 12.8 AFR doesn't neccesarily mean that is what you'll end up with. It needs to be checked with a wide-band. The closer your VE table is the closer your commanded fuel will be to your actual--As far as i'm concerned--who cares if the commqanded doesn't match the actual--as long as you know it and you can correct it with a wideband it will work fine.

**Doc99SS** · 12-20-2006, 04:12 PM

Tom posted one of the best common sense pieces of advise on tuning that I have ever read, outstanding! and so true.

**LS2Tuner** · 12-20-2006, 05:32 PM

NO SPEED DENSITY!!!!
That is straight OLD school tech....... It works off a preset table of figures......So basically if you modify ANYTHING the table is now off......
In plan english that shit is for the birds...... It won't compensate for ANY mods.

DON"T DO IT.

**Sarge** · 12-23-2006, 06:10 AM

SD tune just woke my GTO up. I am highly modded though....I agree with the above post for slightly modded ( H/C/FI) cars.....but we exceeded the frequency of even a Vette MAF....just maxed it out we were flowing so much air.....

ewingr · 01-02-2007, 11:51 AM

Mass Air Flow it will be.

Thanks!

**LS1-68** · 01-04-2007, 01:39 PM

Originally Posted by ewingr

I am putting an '04 Corvette LS1 into my '56 Chevy. I purchased a 0 mile engine on a pallat. It did not come with a MAF.

It has been suggested to me to not get one, and run speed density. But in a very short email conversation (which I may pick back up with him) the guy that I had planned to have my computer programmed by said "I don't support speed density". I haven't had any other conversations with him on it.

So, I thought I'd ask here. Is it a good idea? Bad?

I plan to just drive the car to rod runs, and cruise around. I want it to be streetable/drivable, and don't plan to race it. I of course love having HP, but my interest now is drivability, gas mileage, and no hassles.

What are your thoughts?

I have same situation and i was thinking to spent my money to LC-1, instead of maf. What you guys think about that?
I like to push the pedal, i do not have to think about emissions and fuel consumption is quite same.

I`m a newbie with these computer controlled engines, and i have no idea, how i get this engine started

but i trust myself, and yours help.
Thanks

**408WS6** · 01-05-2007, 06:38 PM

+1 for no speed density. Speed density is mainly for people trying to get every ounce of hp they can. I've heard its good for about 15-20 hp, somewhere in that range.

Having the MAF is definitely better if your goal is drivability.

Although I don't have an SD tune, I'm thinking about getting one. But my car is mainly a track car. So I'm not worried too much about drivability.

**foff667** · 01-08-2007, 06:10 AM

Maf in the end just gives you a little ley way when it comes to mods & such...very little hp/tq to be gained by going SD in most cases...in all out combinations with large cam's & such it can however give you slightly more hp & drivability if done at the right hand.

**LS2Tuner** · 01-08-2007, 12:00 PM

Originally Posted by LS1-68

I have same situation and i was thinking to spent my money to LC-1, instead of maf. What you guys think about that?
I like to push the pedal, i do not have to think about emissions and fuel consumption is quite same.

I`m a newbie with these computer controlled engines, and i have no idea, how i get this engine started

but i trust myself, and yours help.
Thanks

MAF is the way to go all the way around as I explained before.......If you do mods as you go it will compensate........SD will have to be completely retuned!!

**12secSS** · 01-09-2007, 08:59 AM

Originally Posted by LS2Tuner

MAF is the way to go all the way around as I explained before.......If you do mods as you go it will compensate........SD will have to be completely retuned!!

You do realize the LS1 computer uses both the VE Table and the MAF Tables. During throttle transitions the PCM uses the VE Table, and only during steady state (cruising) and WOT above 4000 rpms does it use the MAF table. Old tech TPI system were not this way, hence your thinking possibly.

Either system will need to be retuned to get the most power out of the setup ... you can't say that adding LTs to an LS1 engine without touching the MAF will be fine. They tend to run rich (even with the MAF), hence tuning required.

**tblu92** · 01-09-2007, 02:02 PM

I agree with you 100%--that is how I was taught SD and MAF tuning exactly---I have seen guys add air boxes and go backwards in HP---without tuning--I would recc. a tune after any mod to get all you can out of it--The comp. will learn some--but never enough to be spot on--Like you say especially with LT's --they make such a huge differance in how the engine acts I would never throw them on without tuning--at least the MAF and probabbly the VE table as well--like you said--in transitional unsteady air intake areas the comp relies on both to set the fueling under 4000--having the MAF and VE tables correct will ensure that your commanded AFR will equal your actual AFR-if that is important to you--To someone without a fullbown tuner or a wideband it woud be beneficial to have them correct--Someone with a tuner and a wideband can get away with having them off a bit as long as the actual AFR is set using a wideband in the MAF mode .

**LS1-68** · 01-11-2007, 06:31 AM

Originally Posted by LS2Tuner

MAF is the way to go all the way around as I explained before.......If you do mods as you go it will compensate........SD will have to be completely retuned!!

Ok, i bought MAF. Mostly for that i like to have all orig. parts involved, to start at least.

I´m gonna do tune, maybe in enginedyno, so does it matter which car computer comes, if it´s gonna be reprogrammed?
I need only engine control.
Cold air, hookers, ud-pulleys, i have orig.-97 and msd 38" injectors (too big? ). Planning cam+porting+milling.

Thanks. K

**Street Lethal** · 01-27-2007, 07:08 AM

Originally Posted by 12secSS

... you can't say that adding LTs to an LS1 engine without touching the MAF will be fine. They tend to run rich (even with the MAF), hence tuning required.

The MAF does in fact compensate, but obviously only up to a certain point though. Also, take into consideration the varying weather conditions, as this is where the MAF becomes the most relevant, obviously....

As you correctly pointed out, The LS1 already employs both Mass Air Flow, as well as Manifold Absolute Pressure readings. Both serve an overall purpose, just like torque and horsepower. People need to stop comparing the two, as their meant to work hand in hand for everyday driving.

To the original poster, if your looking for all out strip performance, I'd say go the Speed Density route. For everyday driving (albeit, with just as good "dyno" figures), I'd stick with Mass Air Flow (in which I'm glad to see that you did). I see naturally aspirated, street legal LS1's running deep in the 9's, w/Mass Air Flow.

**LS2Tuner** · 01-27-2007, 08:28 AM

Originally Posted by Street Lethal

The MAF does in fact compensate, but obviously only up to a certain point though. Also, take into consideration the varying weather conditions, as this is where the MAF becomes the most relevant, obviously....

As you correctly pointed out, The LS1 already employs both Mass Air Flow, as well as Manifold Absolute Pressure readings. Both serve an overall purpose, just like torque and horsepower. People need to stop comparing the two, as their meant to work hand in hand for everyday driving.

To the original poster, if your looking for all out strip performance, I'd say go the Speed Density route. For everyday driving (albeit, with just as good "dyno" figures), I'd stick with Mass Air Flow (in which I'm glad to see that you did). I see naturally aspirated, street legal LS1's running deep in the 9's, w/Mass Air Flow.

Exactly!!!!

Theres plenty of fast cars out there running MAF.

And as I stated before it's much more user friendly for the average joe blow!!