Hey guys,

I am looking for large throttle bodies for a custom air intake manifold. Do many aftermarket computers use MAP sensors?

thanks

 

Hey guys,

I am guessing a Map sensor and a mass airflow senor are two different senros now. I think I ment to say Mass air flow senor and not map sensor. I am pretty sure tpi setups do not have a mass air flow senor and jsut ahve a map sensor.

thanks:hail: :hail: :hail:

 

I know 86-87 had MAF. I believe in 88 or 89 they went to speed density. Some early TPI cars came with MAF in 85. And correct me if I'm wrong but didn't they go back to MAF in 92???. And I believe some early 4th gens like 93 had speed density too, then they went back to MAF. I guess GM couldn't make up their minds which was better. MAF is supposed to be more accurate because it measures actual air volumes as opposed to estimating it, as it does in speed density. Thus MAF is more likely to accept lower level mods, because it can sense the change. But to answer your question if I understand it properly, yes, they do make larger TB's. And they make management systems/computers in speed density because of it's programability. If you have speed density, you probably don't want to switch to the more restrictive MAF setup. Depending on your setup and mods, you're probably good with what you have. Even your TB should be fine.. I don't believe switching TB's is the best wasy to spend your money if you're in the beginning stages. And if you have mods, you should be careful of going too big w/ the TB. Come up w/ a plan, match the parts, and stick to it! Don't make hasty and uneducated choices and just buy a TB for the F of it. Infact, I have a 58 mm TB (1000cfm,), but I was running the stock 48mm w/ my supercharger. It was fine; after all it is forced induction. I assume you're thinking about a s/c if you're posting here, so like I said, hold off on the TB and put it towards something that you really need like an intercooler or exhaust. Also, try to be more specific w/ your questions, goals and specs.

 

Hey,
Thanks for the info. I am going to be using a turbocharged northstar engine. I am planning on making intake manifold with help from a local hotrod shop. There aren't many choices for aftermarket parts for the northstar engine. I was thinking of getting the largest thottle body I could. I want to use an aftermarket computer and not exactly sure what sensors would be needed for most competer, and which trottle bodies would have the ability to use the senors.

Thanks for you help:hail: :hail: :hail:

 

Well, my thoughts would be to get the 58 mm 1000cfm, but if you want bigger, I think they make a 1,250cfm, but you might not need this. Anyway, you can use the accell DFI or speedpro management systems. They are the most popular. they can be programmed to work w/ you setup. The latest versions are easier to use. But, know that all of this stuff is very expensive. And if I may ask, why are you using that motor? Is it already built w/ the turbo? good luck

 

no it isn't built. Using the motor because I like the setup it has. Quad cam v8 with varilable valve timing.

Everything about the project is exspenive, I have no problem with saving my money and taking my time.

thanks for your help.

Just to make sure, There is a MAF senor that fits over the tpi setup?

thanks
:hail: :hail: :hail:

 

Good luck with it then. You the right idea about taking your time with it. I'm in the same boat right now. But as you know, it'll be worth it in the end. Sounds like it's gonna be pretty sweet when its done. Good luck, keep us informed.
Oh and when you ask if there is a MAF sensor that fits over the TPI, you don't have to worry. First of all, if you were going w/ the DFI, you don't need a MAF. I'm not sure how you would even use a MAF with the combo that you are running. I'm going to eventually switch over to DFI and get rid of the MAF. But if you were using MAF, it would go "inline" with the air intake ducting. Like on my setup, it is between the air filter and the inlet of the supercharger. Then there is regular ducting between the s/c and the TB. That's it. On your setup, if you were using a MAF, I would guess that you would put it between the outlet of the turbo and the TB. But again, I don't believe you can run a MAF, because you would probably need a factory MAF computer, and then you'd need to costomize the harness, and who knows how you'd get it to work w/ that motor. That system is designed for a regular TPI 350. Ignition, timing and a whole bunch of other stuff is different. I guess, theroetically, if those northstars came with a type of MAF system, you could probably use one of those MAF sensors, but you would need all of the other sensors, wiring harness, computer and what not form one of those cadillacs. And even then, I'm sure the sensor would be restrictive.
Hope this makes sense or helps. If not ask away. But the easiest would definatley be a non-MAF DFI.
later -Justin

 

thought maf were subpost to be better. Does the dfi setup just change the amount of fuel based on teh 02 senor(s)?

thanks:hail: :hail: :hail:

 

No, in the DFI, you set your fuel values and fuel curves, pulse widths and how long it fires. i don't know all that much about the system yet, because I don't have one yet. As far a MAF being better, it's only better because you can do small mods and it will adjust or compensate for them. Once you get into higher horsepoer and more custom stuff, it becomes a restriction and can't be programmed. This is where the DFI stands out. I'm sure you'll need to use DFI. Even if you get MAF to work properly, which will be VERY hard, it will still be a bottleneck.

 

never used fi, it sounds like it would be pretty hard. Is there some way you can setup teh somputer to just learn what the engine can do?

Like, just hook it up and star the eninge and rev it up and down a few times and have the computer be able to tell where it can produce the most power or set it to save the most gas?

thanks

 

I wish you could. only on a lightly modified stock MAF car could you do that.

 

thanks for everything:hail: :hail: :hail:

 

Just making sure. The say you said things it does not sound like dfi comptuers do any tuning on their own, just run the preprogrammed fuel curve. Do dfi have an o2 sensor?

If so is it just to make sure it is not running too lean or too rich?

thanks:hail: :hail: :hail:

 

Well, it would be up to you whether or not you ran an 02 sensor. I definately would run atleast 1 of them, probably 2 or more. 02 sensors will tell you the most about what your motor is doing. You can go crazy and add a ton of sensors like temp and whatnot to each individual cylinder. There is no end. And no, they don't self tune to my knowledge. They may have some settings that you can pic and then modify or tailor to you car. But as far as I know, you would be best off having someone set it up and give you a few programs for your motor. Then as you learn and see what is best, you can start to play around with the settings, do tests, take snapshots and get graphs of exactly what your motor is doing. Every sensor you have, will provide info. You can have a street program, a track program, emissions or other settings, and you can switch back and forth with your laptop. Or you can have someone set it up and then not touch it, in which case you won't need a laptop. Again, I don't own a DFI yet, so I can't be too specific on how they work. But there is A LOT to learn. good luc

 

How could you use more then one o2 senor with a turbo car?

FRom what I understand an o2 senor can not be run before teh turbo due to being pressure senitive.
thanks:hail: :hail: :hail:

 

An 02 sensor is not pressure sensitive. The way an 02 sensor works is that when the exhaust gases get to the sensor, it starts a chemical reaction within the sensor which creates a voltage that goes up to the ECM.

I believe it works something like this: as the level of N0x(Nitrides of Oxygen) increases(high levels of N0x mean you're running lean and low levels mean you're running rich, might have that backwards but you still get the picture) the voltage increases as well. The computer can then take this voltage input and either richen or lean the fuel mixture to constantly create an optimum fuel ratio.

If I'm wrong on this, I'm sure someone will correct me.

 

Well, I don't know anything about turbos, but some of the newer cars have 3 or more 02 sensors and some of them have been turbo'd. I don't think they changed removed sensors, but maybe they did. But I really don't know. maybe someone else could shed some light on this. Sorry.

 

I have asked on the board before about o2 senors. I was told they were pressure senitive and could not be used before the turbo. Was also told that an o2 sensor can not be placed too far from the cylinder because it is heat senitive. Although you can get heated o2 sensors.

 

cool

 

You may believe me and you may not but I dug for info and found out why an oxygen sensor cannot be plumbed in before a turbo. Apparently the amount of backpressure in there will not allow the exhaust to escape completely and so it creates heat soak. The heat soak then makes an oven effect and raises the exhaust temperatures before the turbo. The increased exhaust temperatures would affect the chemical reaction that's created inside the sensor and throw off the readings.

 

The O2 sensor can be placed before the turbo. I figure if GM decided to place an O2 sensor before the the turbo then it'll work just fine there.