hondahater

iTrader: (2)

Ok here is the deal I have a plx wideband comming in in the next few days so I can tune my car however my wastegate is not ported so I may see boost spikes so if I tune the car for lets say 11psi of boost and it runs 11.1 afr and I get a boost spike will the fpr up the fuel pressure? In other words is the stock fpr a rising rate?? I have plenty of fuel mods so I don't have to worry about that however with me tunning my car now it won't be crazy ritch at all times. Any help would be great! Thanks.

ps. I put this in the rotary race section but not enough people are on that section so I wanted to ask it here.

YearsOfDecay

The stock FRP is rising rate, thats what the vaccume line hooked to it does.... however, don't count on it to save your *** on a boost spike.

11.1 at 11PSI is pretty rich IMO, however, it doesn't say you have an FMIC, but i should still think that you could go 11.75- 12.0 without detonation... but wait for a concensus before final tuning...

If you have the SAFC hooked up so that the %throttle input is actually % max boost (which is the best way to do it IMO)... you should be able to tune the car for higher boost instances... the SAFC will "learn" what the maximum range of the boost is, then you can tune to it and the safc will compensate.

Just tune it for 11 psi, whatever %throttle that turns out to be, if that is what you plan on running all the time, then richen the hell out of it above that point on the SAFC, that should cover your *** in case of a spike.

HAILERS

The factory fuel pressure regulator , with a stock fuel pump + rewire, won't get above approx 50psi. I've put MittyVac on the fpr and applied over 10psi to the fpr and the fuel pressure has never risen above 50psi.

So a normal fuel pressure at atmospheric pressure is approx 37-39 psi and when you boost the fuel pressure rises one psi per boost psi, you'd expect something a touch less than fifty psi in the rail.

That said, I've boosted over 10psi for short periods and the afr hasn't risen over 11.5-12 afr. Stock fuel injectors. And a lot of minus in the SAFC.

Evidently not all engines react in the same way as mine (2)

jon88se

Well, according to Henrik's datalogs, the stock car starts running leaner than the AFM's stock fuel "maps" @ 10 psi. However, the stock car runs very rich so anything above 10 psi is really a matter of how safe do you want to be. Reted has claimed several times that a walbro + rewire and FCD is good for 13 psi or so without problems on the stock fuel system.

A big problem seems to be leaning out before the secondaries kick in which is why Henrik created the stage 1.5 ECU which bumps up the duty cycle of the primaries and kicks on the secondries @ 500rpm earlier to avoid the lean spot. The rewire is also wise since the voltage drop @ night with headlights etc...on is very significant on the stock wiring.

hondahater

iTrader: (2)

great thanks guys!

yearsofdecay you said, "If you have the SAFC hooked up so that the %throttle input is actually % max boost (which is the best way to do it IMO)... you should be able to tune the car for higher boost instances... the SAFC will "learn" what the maximum range of the boost is, then you can tune to it and the safc will compensate". Do you mean have the safc hooked up to the boost sensor instead of the tps??? I am going to do that before I start tunning right now it is on the tps from the original guy that had it however like I said I'm planning on changing that. Also I don't have a fmic and no money to right now however that is the very next thing on my list of things to do! So it is not advised to go above 12psi and even at 12 that is only occational right?

Hailers: is 50psi all I would need to boost that high??? I'm real afraid of detonating because of the tmic however I figured it I had enough fuel I would somewhat prevent this. I'm just going to keep my boost controller turned off until I get the fmic.

Would both of you guys say I have enough fuel to prevent detonation???

Thanks again!

hondahater

iTrader: (2)

jon88se, nice points! I would emagine an safc set a little ritch at 3000rpm would do the same thing as setting the secondaries to come on 500rpm sooner right?

HAILERS

When you get your wideband you'll be able to see for yourself (if your running lean at 12-13psi). I don't think you will be.

Just FYI. The intercooler intake temps reach the 200 degree plus level (easily at that) at those boost figures. The stock intercooler is only going to lowe that temp about forty degrees. You have a need for a front mount intercooler if your going to be running over ten psi.

hondahater

iTrader: (2)

ok I'm going to try everything not to boost above 10 or 11psi even if evertything means yanking the turbo off and porting the wastegate. The thing is I've been boosting to about 12-14 pretty easily and I don't want to do this so If there is no way to tame the boost I will keep it off the road until I can afford a fmic.

Ryde _Or_Die

Just port the hell out of your WG and be done with it. It is only a good thing and is pretty simple to do. You will love to able to actually control boost.

hondahater

iTrader: (2)

only problem is that

a)gotta remove the turbo
b)gotta remove the turbo
c)gotta remove the turbo lol did I mention gotta remove the turbo

THats not the only reason also with s4 don't you have to weld a larger flapper on it because if you just port it as large as the stock will go there is still boost creep problems??? Also I guess a big washer would be the best thing to use because I have no idea where to find a honda exhast flang or whatever. ALso do you have to take off the hot side???? Thanks.

SonicRaT

iTrader: (6)

All you need is an exhaust valve or similar, you can find some for chevy engines/etc, just find one that fits your size, have the stem cut off, and then have it welded on. Nothing too fancy. Also, don't just make the hole bigger, you actually need to get back in the passage area and clean it up back there for it to really benefit.

hondahater

iTrader: (2)

passage area???

scathcart

The stock fuel pressure regulator is not a rising rate fuel pressure regulator.

A fuel pressure regulator is designed to be referenced to manifold pressure. When the engine is under vacuum, the fuel injectors will be under an equal amount of vacuum, and when the injectors click open, fuel is actually being sucked in partially be engine vacuum, not just sprayed in from fuel pressure. As a general rule of thumb, for every two inches of mercury of engine vacuum, the fuel rail pressure will drop 1 psi. Under boost, the manifolds are filled with pressure. When the injectors cycle open, this boost pressure attempts to push the fuel back into the fuel rail. For every psi of boost increase, the rail pressures will increase by 1 psi.
The fuel pressure regulator atempts to keep a conastant pressure differential between the manifold pressure and the fuel rail pressure, of around 40 psi. The prupose for keeping this relative differential is that fuel atomization tends to be most efficient at these pressures.

So, we know that the stock fuel pressure regulator increases fuel pressure from its base (no manifold pressure)) setting when referencing boost... why is this not a rising rate FPR?
Well, the rate at which the fuel pressure is referencing boost is a finite amount. A 1:1 rate when referencing boost is not increasing. In order to be considered a rising rate FPR, the amount at which fuel pressure increase with respect to boost must be a rate greater than 1:1.
A RRFOR allows the user to dial in the amount at which the fuel pressure increases with respect to boost... a common setting is 8:1 in aftermarket centrifugal supercharger installtions. In this case, the fuel pressure climbs 8 psi for every psi increase of boost. So, at 10 psi, fuel rail pressures are reaching 120 psi! This puts a lot of extra strain on the fuel injector seals, fuel rails, and also lowers the fuel pump supply volume (fuel pump flow).
A Rising rate fuel pressure regulator is also known as a FMU, or fuel management unit. They are simple mechanical devices used for simplistric tuning. ANY kind of airflow or injector duty cycle tuning is far superior.

That being explained, the stock FPR will react instantly to boost changes... with a fuel pressure regulator and a boost gauge side-by-side, you can watch the two move in synchronization.... looks kinda neat if you spin the gauges so that they line up.

Digi7ech

iTrader: (1)

My experience so far is that the Walbro over rides the stock FPR a bit

I am doing 50-55psi at idle.
My AFR's are in the 11's at idle

I'm still using the stock but cleaned 550's all around.
When my wastegate actuator line burst I went uncontrolled and spiked a few times to 15psi. So far my engine is still alive.

With the stock injectors I did notice that I had a HUGE lean condition right at the 3500(Rtek) secondary kick on point. They went up in to the 13.8 range !!

I then started to lean out around 6500 rpm at 10psi.
Under boost I was doing 11-12 AFR's.

I would say that's where the 550 secondaries start to lose their efficiency.

I have a Aeromotive FPR sitting in my room waiting for installation.
I plan to run the 50-55psi fuel rates for now until I can get a Wideband run again to tune the fuel down to good MPG happy levels.

I think with 720's in the secondaries you will be ok.
Just tuned them rich and then work them down as your checking the afr's.

Better to run rich while tuning instead of lean

hondahater

iTrader: (2)

so is a ported wastegate needed with my fuel mods???


Ps. THanks for all the help guys, It makes a lot more sence now! Things to do before boosting so high

1. clean tmic with mineral spirits
2. set safc to boost sensor instead of tps
3. set the safc to run ritch at 3000 rpm so that there is no leaning out before the secondaries kick in. (do I need to do this with my rewired rx7.com fuel pump?) I guess wide band will tell
4. ??? Anything else you guys can think of?

Ryde _Or_Die

Just port your wastegate man. Trust me. Once you have it off you will see how easy it is. I did mine with a dremel. A dremel will take a little bit to get it perfect, but its very hard to mess up. Then measure how wide the hole is that you end up with (can't really do it too large) and I'd use an exhaust valve (some people have used washers but I'm not too sure all will handle the heat well without warping/bending). Take it to a small machine shop or even an exhaust place and they should be happy to take $10-20 from you to weld it on there.

dr.jones63

It aint that hard to pull apart. Be carefull with expensive gaskets. I made mine out of gasket sheeting material thats sold for cutting your own header gaskets. $8 for everything (DP /Turbo / manifold /engine). Be carefull if you remove the 8mm banjo bolt off the actuator valve, its a bitch to find a new one.

hondahater

iTrader: (2)

ok ok ok I'm going to give it a go since you say you can do it with a dremel but what was this talk of passage needs to be open???

Ryde _Or_Die

I believe he was referring to smoothing out the pathway the air flows out of the wastegate. Backcutting some people call it. Once you have it apart you will see. I did that on my own before anyone said anything about it just because it made sense to me.

Digi7ech

iTrader: (1)

Tip number one.
Be careful with the wastegate lever.

If you break it/mess it up your SOL.
My turbo rebuilder said he could not fix the loose lever on one of my hotsides due to it being shallow and not much material to work with.

hondahater

iTrader: (2)

so did you guys take the hot sides off?

Ryde _Or_Die

Do you mean take the turbo apart? No you don't need to do that. Once you have it off you'll see.

hondahater

iTrader: (2)

cool, sorry for the questions but wouldn't metal shavings be bad???? Thanks.

Ryde _Or_Die

You can stuff a napkin or something in there (I believe I did, but can't really remember its so long ago) or just be creative. And when you're done get an air hose and sprayit out to be sure.

scathcart

I always do.