5sfte fuel

[Spyderdan]

I've seen many supercharged and turbocharged cars run only an FMU with no problems at all. The FMU that comes with most kits are 12:1 to stay on the rich side. Like any mod you want to keep an eye on the A/F ratio to make sure it stays rich under boost. You won't be able to tune for max HP like you can with a stand alone ecu but the FMU is cheap and simple. I would suggest running both an FMU and some type of timing/knock control to be extra safe. The best part about the FMU is that it only adds fuel pressure under boost so while your cruising around the car runs normal and doesn't wast fuel.

If your looking to run higher boost you can also add an adjustable FPR and bigger injectors. You should have a wideband O2 to keep an eye on the A/F so you can lower the base fuel pressure to compensate for the bigger injectors during idle and cruise conditions, then when under boost the FMU will dump in the extra fuel needed.

Remember to always keep your timing conservative and your A/F ratio rich under boost.

If I were to attempt a "cheap" 5sfte this is what I would do:
- Use 3sgte ct-26 turbo/manifold/piping plus an extra elbo for TB (add bigger turbo if cheap enough)
- ebay downpipe
- ebay exhaust
- misc oil and water lines
- 3sgte intercooler
- 3stge oil pan
- would not use 2 bar map (too much timing from tricking ecu) keep stock map.
- add a 12:1 FMU
- add bigger fuel pump
- *maybe add adjustable FPR and NA supra injectors then reduce base FP (could be added later)
- reduce base time by 2-4 degrees for safety
- get a wideband o2 or borrow one and keep an eye on the narrow band o2 after tuning
- see how much boost I could run before A/F drop off

Its fun to daydream...

[Terracar]

Should check out Pressure2's 5sfte (Daily driver) build still running strong 3 years later 60k miles - it is over on Celicatech - plus he has helped several 5sftes live a long and happy life (ie Supershannon)

You need the 2bar map, you need larger than lime tops (460 injectors from rx7)

He has a great write up and step by step - DO NOT USE 315CC INJECTORS - Motor go BOOM (I blew apart 4 pistons using the 315s).

I would suggest taking advice from someone who has done it successfully rather than most the people who have replied due to most only having enough knowledge to be dangerous for this specific topic .

-Terracar

[Spyderdan]

Terracar please give more details about your setup. How much boost were you running and so on...

I've read about the rx7 injector setup in the past but at that point I would want to go full stand alone or at least run a good piggy back. Actually I rather just put the key in my other 3sgte powered MR2 at that point and drive it instead. (-: I'm only looking to go from 130hp to around 190hp on my NA. I'm not planning on running high boost levels and I want to keep the great gas mileage while cruising and overall stock driveability. Just would like a little more power when I put the petal down on my NA.

A big problem that I would want to avoid with the 2 bar map is at full throttle the ecu is only seeing half the load. This means the timing would be insanely high and this would put me at a very unsafe level right off the bat. Then I would have to have a btm or other device to yank the timing way back to keep the engine together. Don't get me wrong I think some type of knock/timing control is always a good idea but I would want to avoid making the timing even more radical by tricking the ecu in the case of the 2 bar sensor. I like the FMU idea because its cheap, simple and proven.

Does anyone have dyno logs of their timing advance while NA and then after adding the 2 bar map? That would be interesting to look at.

[Redstar]

^ With that approach wouldn't your fuel injectors be attempting to run at 100% while in boost?

[Spyderdan]

Do you know how an FMU works?

It raises the fuel pressure in proportion to boost pressure.
The injectors push more fuel regardless of injector duty cycle.
It will not only work but many tried and true supercharged and turbocharged kits use an FMU.

[Enthalpy]

There is one important caveat to be inserted here, now that we are on the topic of overly cheap-a$$ thrills. There is a limit to what certain injectors can endure fuel pressure-wise. You hit a point where it's difficult to open the injector, and your fueling goes way down.

As with any overly cheap solution, individual mileage can and probably will vary. pun intended.

[Redstar]

Originally Posted by Spyderdan

Do you know how an FMU works?

It raises the fuel pressure in proportion to boost pressure.
The injectors push more fuel regardless of injector duty cycle.
It will not only work but many tried and true supercharged and turbocharged kits use an FMU.

Yes I do know how they function, and I never said it wouldn't work. I was just asking a simple question about injector duty cycle, care to answer it?

Could you please include links to a few of the kits you are referring to?

[Spyderdan]

Yeah I think your right it would be close to 100% and your question about the injectors being fully open was because....?

[Spyderdan]

Here's what I got from a quick google search:

AAM | JWT BB530 350Z Twin Turbo Kit

Billet FMU

DRAG Gen 3 Turbo Kit Acura Integra GS-R 1994-2001 DT341IV8

Muffler Guy - DRAG Gen 4 Turbo Kit Honda Prelude All 1997-2001 DT471PDS

YouTube - Chris' Turbo 5.9 Ram Part III -...

[Redstar]

Originally Posted by Spyderdan

Yeah I think your right it would be close to 100% and your question about the injectors being fully open was because....?

BTW I saw the in the first iteration of your other post... I'm withholding my pwn rant because I also really like the idea of a reliable 5SFTE. Please consider the following:

All of those kits, in addition to a FMU, include some way to either trick the map sensor or a piggy back to control things. I've actually used the product in the second link you gave, great product, worked very well on my turbo Dodge when I upped the boost. The gain feature was really helpful to tune with. However, I had larger injectors and a zener diode which was effectively blinding the stock MAP above about 13psi.

To answer your question, I was asking about injector duty cycle because injectors don't typically like to be run at 100% for long periods of time, here are the first couple hits I got from google:
Frequently Asked Questions
http://docinjector.com/info1.htmhttp...uty-cycle.html

While upping the fuel pressure will make an injector flow more, it can not increase the size of the injector substantially or very reliably. Stock is around 215cc, there is no way you will get one of those injectors to act like a 350+cc injector for very long, if at all. Don't get me wrong, fuel pressure is a great tool for fine tuning a setup but should generally not be relied upon as your only source of extra fueling for boost.
Google hits:
Go With the Flow: BASIC FUEL SYSTEM ANALYSIS | Motor | Find Articles at BNET
Dune-Buggy.com - Fuel Injector Sizing
Fuel Injection Mods
First hit from this board:
5SFTE...EMS needed?

I'm really not trying to be an a$$, one thing I really like about this board is the maturity (for the most part ) of the discussions. I'm simply trying to point out that while your approach will work, there are better budget minded setups.

[mrturrari]

Originally Posted by Terracar

DO NOT USE 315CC INJECTORS - Motor go BOOM (I blew apart 4 pistons using the 315s).

That is misleading. You have to pick the correct size of injector for what you are doing and if you don't then yes, your motor will go boom. The 315cc injectors have their place which is in 5sfte setups using the gen2 3sgte ct-26 and map sensor with 10psi or less. I know because I ran that setup reliably for 6 months before my oil pan cracked and I spun a bearing. I thrashed the hell out of that thing and boosted every chance I got. After pulling the head there were absolutly no signs of detonation or any other tuning problems.

People need to understand there are many possible ways to turbo a 5sfe. If you are blazing your own trail though then you would be wise assume that you will need to tune it. Presure2 knows this which is why his 5sfte's have worked out the way they have.

[mrturrari]

On the subject of FMUs, they are fine for small increases in boost like for low boost supercharger or turbo kits and even small nitrous shots where the fuel curve resembles stock. But when you start using turbos that can more then double your HP you are pressing your luck. Turbos change the VE of the motor and the bigger it is the further it gets from the stock maps in the ECU.

So cheap out on the exhaust, the intake, the downpipe, even the turbo itself but don't cheap out on the tuning.

[Spyderdan]

The stock computer doesn't know the car is under boost and of course doesn't have a map table for it. The ECU still thinks your running WOT at X rpm with zero vacuum so its going to reference its max table for fuel output for a NA car.
I would guess that toyota wouldn't push the injectors anywhere near 100% when the driver mashes the throttle and the car still thinks its NA so there is nothing to tell the injectors to go beyond the factory cycle. In reality this probably means toyota has the injectors pushing no higher than an 80-85% cycle and would be no different than me driving my car now as far as injector duty cycle. Plus most drivers are only at full throttle for a few seconds at a time. Even a quarter mile run should only last 15 seconds I would hope.

I agree that you can only push so much fuel to tiny injectors until they stall and drop off. My plan is to put together a simple low boost and low budget 5sfte. Since I have all the part to build a 5sfte with an FMU I just need to get off my lazy butt and start wrenching.

I'm sorry if I've turned this thread into junkyard wars tuning but arm chair tuning is kinda fun.

Redstar sorry about the I misread your post at first and did a quick edit.

[Redstar]

NP, you bring up some good points. I should be doing some datalogging this month, I'll try to remember to post injector duty cycle logs.

I just have a different opinion on how to deal with the stock ecu under boost. I don't actually know what the 5S ecu does when the stock map senor sees boost, it might simply go to WOT maps or it might go into some sort of fail safe. I guess my point is I like boost, my last car saw a lot of it. For me, running my stock injectors near max duty cycle from 0 psi on up isn't an option.

I also paid less for my emanage than this Billet FMU costs.

Kinda related, anyone know if the rev1 5S uses an ignition or fuel cut for the rev limiter?