philcivicjordan

I've kind of over looked this one for a while now. From Google and other sources people are saying to run a 4 bar map sensor. So I checked the one i was linked to its pretty cheap at £25. But there are so many more and all at different prices. . But are there any brands to stay away from?

Also I was talking to a friend about this a while back my car is a 99 civic hatch. So its naturally OBD2 I have the ecu/harness conversion. My friend mentioned having to splice into some wiring to fit the map sensor. No big deal. But both sensors are the same or similar as far as I can gather so I can't see anything that will need changing or cutting in to.

NotARaCist

iTrader: (1)

The "old" way (using a GM 3 BAR sensor) required some wire work. Now, most companies make them in an OEM housing, so you don't have to **** around with any wires.

Before we get into all of this, do you know what a MAP sensor does? Why do you think you need one?

philcivicjordan

Ah sweet. Was gonna say I'd be surprised if there wasn't anything available. With honda anyway.

And yeah It's just reads the air flow going through the intake to determine what fuel is needed etc. They'll have a rating say 1 bar. But if you was looking to run a bar of pressure you'd need a 2 bar sensor from what I've read it's not good to max them out. I know the stock can take so much psi but I'd just like to have a reliable setup where I can add gains when I like and I know I have my **** covered

NotARaCist

iTrader: (1)

Well, you have a rough idea, but that's not quite how it works. What you're describing is more how an MAF works. An MAP sensor reads the pressure in the intake, and adjusts fuel maps based on that. 1 BAR = ~14.5 PSI. Different people say different things, but I'm a firm believer in 1 BAR per 10 PSI of boost. The big thing to realize is that, if you change to a different sized MAP sensor, you need to re-tune. The MAP sensor works as a %.

I'm going to grossly oversimplify this, but it should get across what I'm trying to say. Give an ECU a 1 BAR MAP sensor, and at 14.5 PSI it will tell the ECU "100%". Go to 14.6, or 40, and the ECU will still only see 100%, so it'll fuel like there's 14.5 PSI behind the sensor. Not good. Give the same ECU a 4 BAR MAP sensor, and at 14.5 PSI, it'll read 25%. If the ECU has been re-tuned for the 4 BAR MAP, that's no problem. If it hasn't, it'll feed fuel for 3.625 PSI, and bye bye ringlands.

MAP sensors are also limited in resolution - they can only read at certain % intervals. I don't know exactly what those intervals are, but let's just say there's 100 points - one point per %. To make this short, that means as your MAP sensor gets bigger, your resolution gets bigger, which makes it less precise.

TL;DR of it, run the proper sized MAP sensor for your build, and no bigger. If you're building on a stock D series with a properly sized turbo, you shouldn't need more than a 1 BAR MAP. If you want to cover your ***, ask your tuner to put in a cut (ignition/timing, preferably not fuel) at just past your goals. When I was running 10 PSI, my cut was at 11 PSI. My boost never went past 11 PSI. If you need to upgrade to a larger one, don't cheap out. Spend the money, and get a good one. It's a critical bit of engine management - it fails, you risk losing your engine.

philcivicjordan

So in this case bigger isn't better. My build at the moment is pretty budgeted. I'm only aiming for about 270 bhp at this stage. And that can be achieved with around 8 psi from what I've seen around you tube. So really 4 bar will be overkill 2 bar sounds more suited now. How ever I've only seen stock or 3/4 bar sensors available for honda.

boosted94gsr

Just get a hondata 4 bar map sensor and be done with it. They are about $100 and worth every penny. As you can tell from what notaracist described the map sensor is one of the most important sensors on a speed density based efi system, not a part you wanna cheap out on.

philcivicjordan

That goes against what the guy above is saying though?
Not gonna lie I'm more confused then I expected to be. I'm gonna read into this a bit more

boosted94gsr

You are over thinking it. A quality map sensor like the hondata 4 bar will work perfectly. It's the cheap no name map sensors that are $20 that you wanna stay away from.

NotARaCist

iTrader: (1)

You're half right. You missed the "bigger isn't better" part. If he's only running 10 PSI, he doesn't need to switch out the stock unit, but if he really wants to, a 1 BAR sensor would be fine. 2 BAR would leave room for growth without being too big, but isn't really necessary. 4 BAR isn't needed until you're pushing more than 30 PSI, and would be complete overkill for OP.

boosted94gsr

I agree with you. The only point I was trying to make is don't cheap out on one of the most important sensors in you efi system.

NotARaCist

iTrader: (1)

Oh yeah, definitely don't cheap out on it. I believe Omni makes the Hondata 4 BAR, and they have 2.5, 3, and 7 as well. They range from $105 to $140, straight from Omni. A new Honda OEM 1 BAR sensor is $66 from Majestic. Risking an engine over a $30-$60 price difference is silly, borderlining on stupid.

SpokaneSpeed

Exactly as stated - unless you're going above 10psi you have no need to swap out map sensors. Specially if you're on a budget as u mentioned. Waste of money for your application.

boosted94gsr

I'm pretty sure you are right about omni making the hondata 4 bar map sensor. I know the voltage scaling is exactly the same on both sensors.

philcivicjordan

Yeah im a firm believer of buy cheap buy twice. I just found the difference in prices a bit odd.

Anyway gonna stick with the stock sensor unless my tuner thinks it's needed.

But thanks cleared up a lot of mess for me, will be bookmarking this

NotARaCist

iTrader: (1)

It's the difference between buying mass-produced, barely QC'd Taiwanese crap, or mass-produced, well QC'd Japanese hardware. Just comes down to the cost of production. Better product costs more to produce, and because it's better, the company knows they can charge more for it.

We keep throwing around all of these numbers, but what actually is your goal? I've been throwing around the 10 PSI number assuming you had a reasonable goal, a stock D16 of some sort, and a properly sized turbo. If your tuner thinks you need more than the stock for 10 PSI, well...I'm sure there are at least a handful of better tuners available to you. If there's something we're missing, I'd rather catch it now than look foolish later.

philcivicjordan

I'm b series bro

Running b16a.
Equal length manifold
Twin scroll recon evo turbo
3" straight through exhaust
gonna be running a Walbro fuel pump
Rc 750 injectors

I'm pretty much running the race tech kit. I got it second hand off a friend for cheap.

All I know is I can map my engine to produce 270 bhp in its current state safely. I don't know what psi this would run at I'm just assuming it won't exes 10 psi from what I've seen on forums. So a lot will be left to the tuner/ you guys to advise

boosted94gsr

Are you running a twin scroll manifold with that Evo 16g turbo? I think it might take more then 10psi to make 270whp out of that turbo. I'm interested in seeing pics of this setup once you get it together. Those twin scroll 16g turbos spool retarted fast with the proper twin scroll manifold. I've seen dyno graphs of b series engines making 300tq by 3500rpm with this turbo.

philcivicjordan

Yeah it should be. It's a very popular kit here in the uk people have pushed up to 400 bhp out of them. Currently the turbo is hiding under a **** load of **** and attached to the mani. I've not looked at it since I bought it and the site is down thats why i say 'should be'. But ill get some pics and that tonight