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ri_stang_owner 11-08-2013 02:37 PM

88 lx Speed Density
I have a few questions about my SD mustang, now before i get the typical answers of search the forums or convert to MAF, i have already researched quite a bit and still have some questions and i'm not looking to do more work than i have to so if i can stay SD i'd prefer to. I'd like those who have dealt with or have SD cars to jump in on this as much as possible.

The setup i want to run for my daily driver is this: AFR 165cc heads, edelbrock rpmII intake, 70mm TB, CompCams 1.7 rockers, possibly 24# injectors if needed, 3.73 gears, Eibach shock strut and springs, MM subframes, and PAPerformance 130 amp alternator.

Will i need to modify my speed density system with this setup or something similar to it? if so how?
Issues you have run into while running a similar setup on your own car with SD?

Thank you in advance for all the help.

dawson1112 11-08-2013 02:58 PM

If your not swapping the cam I wouldn't worry about to much. Cam selection is the most important thing with the SD cars, because most after market cams create less vacuum and the SD system uses a predetermined idle vacuum amount greater duration cams reduce vacuum causing idle issues. You can run aftermarket heads, intakes , and headers , but since the map sensor cant read air flow you may be some what limited in HP.

ri_stang_owner 11-08-2013 03:09 PM

awesome thanks for the info. I've heard of some people buying a custom grind cam to counteract this problem but im thinking if i start diving into changing the internals it won't be for quite a few years and by then i'll probably do the MAF when its more convenient. I'm not worried about limited HP because im not looking for a radical setup by the parts i listed, just a fun safe DD with a lil more gallop than stock. Any recommendations on do's and don'ts with anything? also do you think i'd be safe with stock injectors on these?

dawson1112 11-08-2013 05:43 PM

Honestly I think youll do just fine with the 19lb injectors that are in the car. I am fairly sure that if you go to a 24lb injector youd need to have a tune done to keep it from running rich, Im not to sure on the speed density since going to bigger injectors on a maf car you can tune for them with the maf. On the SD any thing greater than stock injectors on your stock eec will require some kind of tune and to do that youd need a chip and a wideband to look at the a/f ratio. Further down the road if you want to add more power to it you should look at going to MAF.

Also if you can I would defiantly do the 3.73 gear swap, that would wake that ride up considerably all by it self.

ri_stang_owner 11-08-2013 05:51 PM

i put the 24# injectors as a possibility in case the car is running lean but thats the only reason i'd bump it up. the 3.73's are the first thing going in the car pretty much ha that and the subframe connectors and all the suspension mods possibly in one big weekend since they all coincide practically. last things to go in will actually probably be the heads and intake, i want the car to handle well before more power is added.

dawson1112 11-08-2013 06:09 PM

The sub frame connectors are really nice I have em on mine, they definatly keep the car planted and a lot more stable feeling when you jump on the throttle hard. I would think about getting some upper and lower control arms as well.

ri_stang_owner 11-08-2013 06:42 PM

Yeah the full length welded subframe connectors im thinking is almost a priority with any mustang. I was looking at them but was unsure, what do they offer other than just replacing another part that can cause problems? im still semi new to this.

dawson1112 11-08-2013 07:14 PM

If your asking what the control arms do. The stock control arms have a lot of flex in them , this is fine under normal conditions and at stock power. How ever once you start adding a lot of extra torque from power adders and gears they flex too much this can cause such issues as snap over steer , pinion bind, wheel hop, as well as the axle to shift out of alignment on hard acceleration giving you the feeling of the rear end sliding out.

The sub frame connectors give a lot of rigidity to the body and help stop the body flex , also assist in dumping some of the weight from the front to the back upon launch. Normally with out them upon a hard launch the front comes up but the body flexes and twists , when you tie the rear sub frame in to the front it stops most of this flex and forces that energy to the rear tires giving better traction.

I am sure there is someone on here that can explain it better than I can , and Im not an expert in suspension. But both control arms and sub frame connectors are a great benefit.

ri_stang_owner 11-09-2013 07:39 AM

this morning i just looked up control arms, i'm thinking of going with the J&M weight jacker lowers and then uppers to match. Based on the reviews everyone loves them and they last a long time so should be a worthy investment that i won't have to worry about a few years down the road.

87 T TOP GT302 11-12-2013 07:37 AM

Thank you for your service to our country. I know yesterday was veterans day and all of those whom serve or have served deserve our respect.
As for your project you can try the 19lb injectors first to see if it bogs. On my 87 I use to run the 19s but the car seemed too lean. With the 24's it's a lot better.

JPJP 11-12-2013 09:26 PM

Hey 87 T TOP GT302, are you still running Speed Density?

I am Supercharged (Paxton SN89) and still running with 19 lb injectors and SD. I MAY bump up to 24 lb injectors but am happy so I figure leave it alone.

87 T TOP GT302 11-13-2013 08:13 AM

I still am speed density. I have added an idle adjustment plate .It allows you to fine tune the idling .I purchased it from Mustang unlimited. I have been adjusting and the best I can is idle at 1100 rpms.

ri_stang_owner 11-13-2013 03:56 PM

thanks for the info guys, how can i tell that my car is running lean?

87 T TOP GT302 11-19-2013 04:00 PM

Every Mustang is different but with mine it seemed like it needed more fuel .It wasn't bogging but when I nailed it seemed to need more fuel. Lean may not be the best way to describe the condition. All I know is with the 24 it just runs better especially at full throttle.

dawson1112 11-19-2013 06:40 PM


Originally Posted by 87 T TOP GT302 (Post 8311145)
Every Mustang is different but with mine it seemed like it needed more fuel .It wasn't bogging but when I nailed it seemed to need more fuel. Lean may not be the best way to describe the condition. All I know is with the 24 it just runs better especially at full throttle.

Obviously your issue is more related to having a lumpy cam. SD cars are prone to idle, fuel ratio and drivability issues with aftermarket cams.

Your cam choice is not to bad , but it still lowers your vacuum quite a bit and the MAP sensor is seeing this low vacuum.

You could gain so much more out of your setup by converting to MAF. I suspect your low end throttle response leaves a little to be desired, but once you hit WOT she screams like a banshee.

The op is not swapping out cams so the stock 19s should suffice .

87 T TOP GT302 11-20-2013 11:12 AM

Dawson 1112 thanks for your response. I believe I've gone as far as I can without converting to mass air. That being said it idles good for the most part .
You said something about gaining so much by converting to mass air .What would I gain other that fully controlled idle ? I mean performance wise is there any gain ? It seem to me to be a waste so what am I missing ? I've never had a mustang with mass air so I don't know what I'm missing or not.

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