Safe HP on an FMU setup

[AZ89two4Tsx]

Hey guys, I'm gonna try to start piecing together a mild turbo kit for my sohc and being mild and all, I was just going to go the FMU 8:1 route. From what I see people usually run a t25 at stock boost and are done with it. But I hear the FMU setup can work with t3/t4s as well. I was wondering what the limit should be when running the FMU with the stock injectors. I'm trying to find a turbo and was looking for either an s14 t28 or a slightly bigger t3, t3/t4 like off of a volvo, z31, or something. I wanted to go for the t3/4 but didn't know if that's pushing it and where I would go about finding the right turbo. So can you guys point me in the right direction as to the right turbo and right overall setup? I'm looking to stay with the FMU route and not have to deal with all the ecu/electronics work.

[WDRacing]

If you retard the timing you can probably get away with 10psi of boost. I woulnd't run more then that though, fuel pressure gets to high for my liking.

WD

[AZ89two4Tsx]

^ Yeah, that's about what I was thinking. I'm kinda leaning towards a t3 turbo, any suggestions on donor cars to look for? I'm not gonna buy a brand new turbo but I'm not gonna buy a piece of junk either so I don't really know where to start. I hear of people using turbos off of volvos and z31s, how do those fair? And 10psi is on a t2 I'm assuming right, or does it not really make a difference?

[Razi]

The turbo doesn't make a difference.If you run more than 10 psi on the turbo, the FMU will be making the fuel pump work very hard.

[AZ89two4Tsx]

^ Are you talking about a stock fuel pump? I was going to run a walbro definately. Isn't that a given with any KA-T?

[Razi]

Yes, but I don't think pushing around 100psi on the fuel pump is recommended.

[oz240red]

AZ89, I'm doing the same thing as you. Great that you asked this question.

I am putting a t3/t4 but only boosting to 6-7psi just to be safe.

When I save up some more, I was thinking of 555cc DW injectors and a JWT tune. (My goal will be 300hp) That's like $800 more. Plus I believe a SAFC is needed for fine tuning...

But for now I bought the walbro 255 pump and an 8:1 FMU like you. And, like WD said, I'm going to retard timing (don't remember how many degrees) and use colder spark plugs (the part number is on the stickie)

Good luck and keep us updated.

[neverlift]

I'll chime in... a local guy ran 12psi and made IIRC 310whp or something, dont recall exactly but it was a nice afr and power was smooth.

I ran stock injectors to 75psi on an afpr and ran 11psi on a t25 and 8~10 on a saab t3, but that was with a custom tuned ecu for timing and some fuel tweaking...

I have a 12:1 fmu I will be putting on in series with the afpr, I have a few ideas to toy with. Kid I got it from said he ran it to 19psi with 310cc on his honda, I'm sure it was well beyond taxing the fuel system. I plan to recalibrate it and or use a mbc to bleed off and delay onset of rise, I think it will be do able to 12 psi, with 4*pulled. I dont plan to let the fuel pressure to go over 115psi, but I will cross that bridge when I get there. I know for a fact stock injectors at 75psi will handle 7psi of boost. And that is only increasing fuel by 4.5psi per lbs of manifold boost. Honestly I cant wait to try.

[oz240red]

Since a FMU raises the fuel pressure based on psi on the intake manifold, the more PSI the richer you will be right? Would this be where a SAFC would come in handy to measure air-to-fuel ratios and lean it out?

Would the increase in fuel pressure when boosting at 7psi be something to worry about as far as gas getting into your oil because you are too rich?

[240RB1]

i am also going this route (FMU wise)I have a rb25 t3/t28 mut that i will be using on an 8:1 fmu at 7-8lbsof boost

i had an old volvo turbo off a 7series ithink it was a straight T3 and sold it to my friend bloodsport he now has it in his single can running 9lbs but with a tune and injectors though.i say get a volvo turbo, they arent hard to find and are a pretty nice size for a moderate power gain

[AZ89two4Tsx]

Is there any special model/year turbo to look for or are they mostly the same?

And btw !240RB!, how much does an rb25 turbo run on average?

[neverlift]

I bought and broke one for 75 bux... asked the guy about another and he wanted 150 anywho, 8 psi should be fine with an 8:1 and a degree or so pulled. You will be right over 100psi of fuel pressure, 107.5 would be exact. see the reason I plan to use an afpr and the large 12:1, with a restrictor and a mbc, I can always go back to the zmaf and my sohc ecu.... ut want more simplicity, I think turning a couple screws would be pretty easy

[240RB1]

AZ89two4Tsx a used RBturbo can run anywhere from 150-250i guess i payed 200for mine with the stock exhaust elbow and in really good condition,i somewhat regret buying one beacause everything that touches the tirbo will have to be custom like the manifold,coolant lines, oil lines exhaust dump pipe downpipe yada yada yada

[AZ89two4Tsx]

Bump!

What would the HP difference on 8psi be on the usual four turbo choices?

t-25, t-28, t3, t3/t4

If it's really not that big of a difference, I'm not going to shell out double or triple the $ for a turbo on this mild kit I'm going to be building. And which brand of fmu do you guys suggest? I hear Vortech going around alot.

[oz240red]

Not sure about specific HP on the setups (check out this thread zerothread/252368 and see if there is something similar to what you intend to piece together).

I went the T3/T4 route at 7psi with the FMU setup as a starter setup. I finished installing it last night and tried it out this morning and I'm posting how it's turning out there, maybe it can help you get an idea.

Good luck

[tehzack]

You should really save a little more money and get a rom tune. Turbo charging a car on stock injectors, stock fuel pump, and NA timing maps is a terrible idea and even if you get lucky and it doesn't blow up you won't be making nearly as much power as if you saved up for a few weeks and bought a decent tune. Unplugging/replugging an ecu is a far sight easier than removing/replacing an engine.

[WDRacing]

You should really save a little more money and get a rom tune. Turbo charging a car on stock injectors, stock fuel pump, and NA timing maps is a terrible idea and even if you get lucky and it doesn't blow up you won't be making nearly as much power as if you saved up for a few weeks and bought a decent tune. Unplugging/replugging an ecu is a far sight easier than removing/replacing an engine.

The FMU + low boost + a slight retard of base timing works very well for a beginner. There is nothing wrong with going this route at all. No it isn't the best, nor does it make the most power...but it does work. Which is the end goal for most beginners on a budget. A good rom tune is $550 or better, plus injectors gets you close to 1K vs an up and running KAT for $150.

After running a low boost setup, they can also determine how much more power they would actually like. This will assist them when it comes to injector size etc when they decide to upgrade.

FMU does NOT = blown motor.

WD

[480sx]

^^ what he said

[pancho y onions]

Going the the FMU route def gets you into the learining curve of things but i really wouldnt trust going over 8lbs. If ya just get a rom tune you will feel so much more comfortable driving and not worrying much about your motor taking a crap.

[boznuttz]

I ran 4 psi safely on a nice T3/T4 setup with an 8:1 with no problems. It was fun as hell. I was considering upping the boost for a bit until I relocated the battery to the rear without an inline fuse and shorted out the ecu or something. Since I've been so busy with finishing up my bachelors and applying to grad school, I really don't have time for it anymore. It's a shame though, it was a ton of fun. Putting it up for sale now makes me wanna cry. It's always the little things that annoy the living piss out of you, lol.

[livinglegend2100]

I ran 4 psi safely on a nice T3/T4 setup with an 8:1 with no problems. It was fun as hell. I was considering upping the boost for a bit until I relocated the battery to the rear without an inline fuse and shorted out the ecu or something. Since I've been so busy with finishing up my bachelors and applying to grad school, I really don't have time for it anymore. It's a shame though, it was a ton of fun. Putting it up for sale now makes me wanna cry. It's always the little things that annoy the living piss out of you, lol.

how much HP was it putting out with the t3/t4? you think i could run 6 or 7 psi on it safely?

[boznuttz]

When I first got the wastegate, it had a 7 psi spring in it. I just retarded the timing and ran 93 with no real issues. I'd say I had a good 160 or 170 to the wheels on 3 to 4 psi. I didn't mash on it at all with the 7 psi spring just since I wanted to stay safe. I was going to use my friend's wideband, but that fell through so I said to hell with it and put in the Tial 4 psi spring.

[AZ89two4Tsx]

So it sounds like if I get a t3 or t3/t4 I wouldn't want to go over probably 7lbs? Idk, I'm a noob, just want something that puts out a consistent and RELIABLE 200HP.

Btw, how necessary is upgrading the clutch starting to become?

[480sx]

You can run 7-8 psi on a FMU with no problems. Just a 2-3 timing degree, whatever turbo within reason, and your fine. It will get you into the 200hp range reliably.

Your clutch might hold it might not. Your increasing your TQ by about 50 percent, but stock clutches have surprised me a few times and held a lot more HP than they are made for. Its not gona last long most likely, but it should hold you over for a while until you can get a performance clutch. I wouldnt push it to long, a blown out clutch on the side of the road is a bish.

[oz240red]

I'm running the T3/T4 at 7psi with the FMU and my clutch is slllllliiiiiiiping when boost gets close to 7psi. I'm in the process of getting a performance clutch, I was looking at the NICO special on Competition Clutch...

I'd love to dyno it, but that won't be possible until the new clutch is in.

[AZ89two4Tsx]

Wow, I guess I'm in luck. My transmission is in need of an overhaul so I'll probably replace the clutch assembly once I get it rebuilt.

How much does a transmission rebuild from like AAMCO or something cost? And what clutches do you guys suggest?

[480sx]

Comp clutch, and ACT have the best rep. I personally like my Spec but a few people have had some serious issues with their clutches.. Specifically the sprung clutches having their springs come out of the clutch and wreck sht.

[boznuttz]

I put in an ACT 6 Puck unsprung hub. I personally loved it once I got used to it. Mr brother also had the same for his SR'd hatch and was putting a reliable 220 to the wheels with absolutely no slipping.

[ilovesideways]

Hey I have a quick question, I have heard from different people that the SR turbo manifold can be used on the KAE, is this true?

[480sx]

Nope.