larger throttle body on speed density?

[Unregistered]

Can i upgrade to a larger throttle body on a 87 302 speed density? Also, what about using underdrive pulleys?

 

[mtkawboy]

Pulleys might help but it also may run hot and undercharge the battery. Throttle body wont work because speed density cant compensate for the additional air flow. Everything is set for the stock motor at the factory. You will need to convert to mass air for performance mods which can compensate for the additional air flow. Very few near stock motors will make more power with a larger throttle body in my opinion. Someone elses may be different

 

[Unregistered]

How hard is it to switch to mass air? Is it simple plug in or mass air sensor? Where can i get the parts?

 

[Skuzzlebutt]

It's a fairly easy swap. it does require a new computer as well as the MAF & related wiring.

 

[Ryan]

you don't need mass air for a larger throttle body %)
you can do a lot of stuff to a speed density motor before you NEED mass air. ;D

 

[expobronc]

i ran a mustang a STOCK mustang TB on my 87 t-bird setup for a while and even though the mustang is only like 10 mm bigger than the t-bird throttle body, I could feel a difference. The bigger throttle body caused a noticable hesitation.

Maybe i didnt leave it on long enough to let the computer learn, but thats just my experience

 

[Ryan]

did you open the intake to match the larger throttle?????????????
if there is a big ledge there causing a flow problem that would cause problems.

plus you have to check the TPS sensor with hesitation problems, it was probably the real problem.

A Bronco Driver mag this summer will showcase several EFI engines. 3 very modifyed engines on the stock speed density computer

 

[RKM]

Adding a TB will not hurt your speed dencity computer. Thats like saying you cant put a set of long tubes on it... I agree with the TPS. YOu need to check that setting. SOme times that little sinser will go bad. It should read no more than .999 V at WOT with the key in the on position not running. Some people will set it lower than .999 like around .97 or so to allow for a little if something moves.

I wouldn't go crazy and get a monster 70-90+ mm TB though. These require motors putting down some power. If you stay with a stock mustang 87-93 TB it is a 60mm, the 65mm will make it a little more crisp if you have your motor tuned very well. Correct FP, timing, filter, K&N, pullies, 1:7.1 rockers etc etc. I wouldn't think you could feel much with just the TB.

 

[iwlbcnu]

You can do anything to a speed density set-up except go to a radical cam. The cam is the only real deciding factor. Heads, intake, TB, headers will have no effect on it.

To be honest, the SD system is actually better than the MASS-Air, it just requres a custom chip to accept big power cams. Look at the 5.0 racers and they mostly run SD systems.

 

[trailpsycho]

I was under the impression that you couldnt modify the intake/induction components on a speed denisty, thats why MAF was the way to go.?? Is it just that the MAF can relearn the cam changes, where SD cannot and so as long as you run the SD with the stock cam you are OK? Again, heads can be modified, bigger TB, GT-40 intakes, bigger exhaust, etc are all OK mods? Or am I reading too much into the last few posts. I thought all these variables were too much for the SD computer to learn and that it wouldnt run well with many of these mods. Straighten us out on the cam, induction and other mods on a SD vs MAF setup, Ryan or anyone else...an inquiring public wants to know. I have often seen (and believed that) the SD motors (86-88 HOs and many other 5.0 non HOs) sell much cheaper b/c they "were not as desirable as an MAF ". No more secrets.

 

[RKM]

The record holder for NMRA factory stock. Is a friend of mine. His car is SD.

What you hear is correct. THe biggest upset to a SD system is the limiting factor of its no ability to adjust to cams.

You can have heads, intakes, etc. etc. and run a SD system. But when you get that far into it. You will gain more power by adjusting the computer with a custom burned chip. Then go a head and add the cam also. A good dyno shop will ask for cam specs and motors specs when dynoing a car or truck, That way they have a good idea on the first burn for a chip and then they work on the tune from there.

 

[Ryan]

A) you can change intake, heads, cam, everything with a Speed Density. If you know what parts will work togeather, and what parts will agree with the computer.

B) getting a chip or tuning a computer is $350 - $1000 or more. So if you engine is not to extreme, mass air is a cheaper way to tune the engine

C) Mass Air is not able to "adjust" or "learn" any cam. you have to be just as carefull with camshafts.
Cams effect engine vacuum, so that screws up Speed Density if not carefull. Mass Air does not care about vacuum
Injectors are timed to open at certian times in relation to the cam sensor, all comptuers will have issues if the cam grind is extremly different than the original in the program.


ALL THIS AND MORE WILL BE IN A FUTURE BRONCO DRIVER.

 

[iwlbcnu]

I might have the terms a little off, but should get the point across. the main culprit between the 2 are SP runs off A Map sensor (mainifold atmosphere pressure) where as a MAF system runs off a Bap sensor (barometric atmosphere pressure) so because of this a certain vacumn is required for SD.

RKM- I don't keep up w/ the records that much, but are you referring to Bob Cosby? I don't think so since he is running a 99 now.

 

[RKM]

No but he is up there in one of the other classes. Justin Burchim had the fastest Stock class mustang recorded. He won the 02-03 class. Now days they let the cobras in, and you can run heads from other ford cars. etc. etc. the rules have changed. He was running a fox body. I used to race against him at a local track.

 

[mtkawboy]

Where can you still get a custom speed density chip made? Ive tried everywhere with no luck. RKM I emailed you on your web site today about this

 

[RKM]

I think you may have emailed someone else. I didn't get anythig. Any dyno shop should be able to burn a chip for you. You might want to just call a manufacture like Diablosport, superchips, jett performance. etc. directly, and they will point you in the right direction. They should be able to tell you of a few good shops in your area.

 

[trailpsycho]

I think he meant Ryan, RKM. He has you confused with Ryan of FFI.

 

[Ryan]

why do you want a Speed Density chip????
It's pointless waist of money %)
Mass Air conversion is 1/3 the cost and much better results

 

[iwlbcnu]

It all depends on what you are doing. I can buy complete running SD cars around here for $150. A wrecked Mustnag is $1500. Until you go radical on the cam, the SD will be all a Bronco person needs, it had one less air restriction, less parts for a cleaner install.
For the majority of Bronco owners MAF is overkill.

 

[Ryan]

%)

Why do you have to buy the entire car?
Computer $125
MAF sensor $25
MAF pifgtail $10
VSS pigtail $7
------------------------
total $167 to convert a SD system to Mass Air


Chip will cost $350 or more + shipping, and it probably won't be right the first time. So you'll pay more in shipping it back and forth untill the program is correct. Speed Density chips are not easy.
All the chip tuners I know, that are worth paying to do this, will talk you into a Mass Air swap first.

SD is cheaper, and will probably fit the needs of 95% of the early Bronco swaps. But the cost to convert is so small, with lots of gains. It's a no-brainer.

P.S. MAF system does not run off the Baro pressure signal. LEarn before you type please %)