speed density systems

guitardawg · 09-17-2003, 10:31 AM

I have an 88GT (non California)(AOD) which I understand has speed density system instead of the mass air flow. It is stock. I want to start modifying it for mainly low RPM HP/eff. I'm wondering how far I can go with modifications, before having to convert to mass air flow. I have several injectors leaking fuel. I have aquired a used upper & lower stock intake; including the injectors (stock 19#). Is there any way to have the injectors checked before intallation? I'm planning on getting a 65mm TB/EGR plate & porting the upper intake to match. Is there anything else I can do to the stock intakes. I do plan on getting the phenolic spacer between upper & lower. What else should I consider doing while I have all this apart? Do I have an air silencer that I hear about? Can the speed denisity Volumetric Efficiency lookup tables be modified or in other words expanded for more radical mods?

88workcar · 09-17-2003, 12:41 PM

Do what you want. It all works.

Dark_5.0 · 09-17-2003, 01:08 PM

Hey 88workcar update your sig man

I have alot done to mine with speed density and it runs like a champ.

88workcar has more done than me.

guitardawg · 09-17-2003, 04:52 PM

Thanks for the response. I looks like I "can" do what I want after looking at what ya'll (yep I'm from Texas) have done. Do either of you have larger than stock injectors & did you have to have to do anything to the ECC to let it know there are now larger injectors installed or is all that sort of thing just apply to mass flow sytems?

Dark_5.0, I thought that all mustangs after '88 had mass flow systems or did you convert your '90 to speed density?

Dark_5.0 · 09-18-2003, 01:18 PM

I bought the 90LX as a rolling chasis and swapped everything over from my 88GT.

A fuel pressure regulator is a must when tuning speed density cars. Bigger injectors are a no no on a speed density car.

If you do enough to outgrow the 19# injectors its time to switch to mass air. You have to be near 400 HP to outgrow them though.

guitardawg · 09-18-2003, 03:01 PM

Dark_5.0

Thanks, that clears up alot for me. I'm just learning about all this. I see you have the 190 lph fuel pump. Was there a certain fuel pressure that you reached when the stock pump was not up to it. I'm assming stock fuel rails are OK also up to a certain fuel pressure.

Dark_5.0 · 09-18-2003, 03:26 PM

My car was still running fine with the stock fuel pump I just upgraded it for peace of mind.

The fuel rails are good all the way up to 500+ HP.

09-17-2003, 10:31 AM	#1
guitardawg Registered Member Join Date: Sep 2003 Location: Somerville, TX Posts: 3	speed density systems I have an 88GT (non California)(AOD) which I understand has speed density system instead of the mass air flow. It is stock. I want to start modifying it for mainly low RPM HP/eff. I'm wondering how far I can go with modifications, before having to convert to mass air flow. I have several injectors leaking fuel. I have aquired a used upper & lower stock intake; including the injectors (stock 19#). Is there any way to have the injectors checked before intallation? I'm planning on getting a 65mm TB/EGR plate & porting the upper intake to match. Is there anything else I can do to the stock intakes. I do plan on getting the phenolic spacer between upper & lower. What else should I consider doing while I have all this apart? Do I have an air silencer that I hear about? Can the speed denisity Volumetric Efficiency lookup tables be modified or in other words expanded for more radical mods?

09-17-2003, 12:41 PM	#2
88workcar Registered Member Join Date: Oct 1999 Location: Pierre Part, La. U.S.A. Posts: 1,850	Do what you want. It all works. __________________ 88workcar 1988 Mustang LX 342. 417rwhp @ 6800. 28 X 10 ET Drag, 4.30s, 10.69 @ 126.43 1.42 60ft. 11.13 @ 127.7 on BFGs 1.72 60ft Rice Hater # 42 To be old and wise, You must first be young and stupid I'm somewhere in tthe middle.

09-17-2003, 01:08 PM	#3
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	Hey 88workcar update your sig man I have alot done to mine with speed density and it runs like a champ. 88workcar has more done than me. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

09-18-2003, 01:18 PM	#5
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	I bought the 90LX as a rolling chasis and swapped everything over from my 88GT. A fuel pressure regulator is a must when tuning speed density cars. Bigger injectors are a no no on a speed density car. If you do enough to outgrow the 19# injectors its time to switch to mass air. You have to be near 400 HP to outgrow them though. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

09-18-2003, 03:26 PM	#7
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	My car was still running fine with the stock fuel pump I just upgraded it for peace of mind. The fuel rails are good all the way up to 500+ HP. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

09-17-2003, 04:52 PM	#4
guitardawg Registered Member Join Date: Sep 2003 Location: Somerville, TX Posts: 3	Thanks for the response. I looks like I "can" do what I want after looking at what ya'll (yep I'm from Texas) have done. Do either of you have larger than stock injectors & did you have to have to do anything to the ECC to let it know there are now larger injectors installed or is all that sort of thing just apply to mass flow sytems? Dark_5.0, I thought that all mustangs after '88 had mass flow systems or did you convert your '90 to speed density?

09-18-2003, 03:01 PM	#6
guitardawg Registered Member Join Date: Sep 2003 Location: Somerville, TX Posts: 3	Dark_5.0 Thanks, that clears up alot for me. I'm just learning about all this. I see you have the 190 lph fuel pump. Was there a certain fuel pressure that you reached when the stock pump was not up to it. I'm assming stock fuel rails are OK also up to a certain fuel pressure.

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