CT26 + Maximum Boost Options

[lagos]

Its better to be safe than sorry right ? 75 bucks for an upgraded rail is better than rebuilding and entire engine.

Flowbenchs have proved that the stock fuel rail leans out piston number one.
After a certain amount of turbo pressure.

yeah i remember reading some stuff on that, but i always thought it was only an issue once you start to uprade past the stock injectors.

[presure2]

the deal is this: with an upgraded fuel pump (like all of us swappers run)
there is a pressure drop across the rail of 14-17psi at the #4 injector VS the #1 injector.
basicly it is because of how small the hole is that provides the fuel across the rail to the injectors.
you can read all about it here:
http://www.mr2oc.com/showthread.php?t=60913
the highlights:
• One should NOT run a larger fuel pump with the stock Gen II MR2 Turbo (3S-GTE) fuel rail.
• One should NOT run any fuel rail with 550’s with the stock Gen II 3S-GTE fuel pump above 10 PSI boost. The stock fuel pump cannot keep up above 52 psi of line pressure. Even though the test data shows a 60 psi test was run, when the injectors opened in this test, the pressure dropped to 50 psi!!
• The Gen II 3S-GTE factory FPR, supply lines, and return lines can handle a larger fuel pump without problems.
• Both the supra pump and the Walbro pump (255 lph) can keep up with 850 cc/min injectors.

[Defgeph]

yeah i remember reading some stuff on that, but i always thought it was only an issue once you start to uprade past the stock injectors.

Anytime the fuel pump is upgraded on a GenII 3sgte and new rail is a must. Otherwise over time, the engine will fail. Once the fuel rail is upgraded, you can safely run larger injectors or larger pumps.

That thread Manny just posted has excellent information. Nice find.

[BBoYRuGGeD]

I think i should upgrade my rail now...anyone have any opinions of the ATS rail here?

ok so an upgraded fuel rail is a must with an upgraded fuel pump (us swappers have already)...but is this at a certain boost? like manny said...at 14-17 psi theres a drop in pressure at #4 vs #1...so people should still be safe below those boost levels correct?

so far at 10psi the duty cycle of the injectors is 100% and at 14+psi the rail will need to be upgrade because us swappers already have upgraded pumps...correct me if im wrong. theres some great info here!

thnx manny that link was real informative

bboy

This post has been edited by BBoYRuGGeD: Feb 4, 2006 - 12:34 PM

[Defgeph]

Why chance it?, the rail is only 75 bucks. Think about everytime you slighty over boost to 11psi ur leaning out #1. Another note, you have a manual boost gauge. you could have a wrong boost reading. you could be boosting @ 12psi and not even know it.

And EBC with a boost gauge built in is a great investment.

[BBoYRuGGeD]

ok so the RAIL will lean out #4 at 10psi? i thought it was 14-17psi from what manny said?

because of this topic...i will be upgrading rail sooner or later

and what about the 100% duty cycle of the injectors at 10psi...anyway of getting around this? new injectors or is this ecu controlled?

bboy

[Defgeph]

From what I have seen the stock injectors are fine for the CT26. The weak point in the fuel system is the rail.

Once replaced I think everything will work fine up to 15 psi.

[presure2]

ok so the RAIL will lean out #4 at 10psi? i thought it was 14-17psi from what manny said?

because of this topic...i will be upgrading rail sooner or later

and what about the 100% duty cycle of the injectors at 10psi...anyway of getting around this? new injectors or is this ecu controlled?

bboy

i didnt mean boost level, i meant a 14-17psi FUEL pressure drop across the rail.
ALL the time, at ANY boost level.

[tangcla]

Does the fuel rail need to be upgraded with an ST205?

[presure2]

Does the fuel rail need to be upgraded with an ST205?

i dont believe any of the testing they did included the 3rd gen. so i cant really say for sure.
although with the stock 550s and bigger pump, i dont think there is an immediate cause for concern

[tangcla]

ahh k. cos I already did the fuel pump with a Walbro GSS341 255lph

Interestingly, I get better fuel economy while the car runs richer...

This post has been edited by tangcla: Feb 4, 2006 - 5:14 PM

[Insanity-74]

Up to and including 850cc injectors can use the origional fuel rail with some slight modifications 1000cc will need a new fuel rail

[lagos]

here is something to keep in mind tho. all these tests and claims of cylinders running lean is all "in theory" type of stuff. the test were done by WolfKatz, a company who sells nothing but fuel rails. so just keep that in mind.

like jeff said....for 75 bucks, why not... but i dont think its a problem i would loose any sleep over. i dont think any 3s owner ever pulled out his spark plugs to find one of them was running lean.

[BBoYRuGGeD]

i didnt mean boost level, i meant a 14-17psi FUEL pressure drop across the rail.
ALL the time, at ANY boost level.

oh...then i guess i better get crackin' on that rail soon cheap and good reliable insurance....cant go wrong with that!

bboy

edit: on a side note...i agree with lagos that this issue is not that crucial and should not be that big of a deal for most future swappers, specially those who plan on staying on or below 14psi for awhile. reason i say this is i dont really know anyone who has had any issue with the stock rail on upgraded pump... be it celica, mr2, camry, or whatever car a 3sgte has been swapped into.

This post has been edited by BBoYRuGGeD: Feb 5, 2006 - 1:40 AM

[presure2]

edit: on a side note...i agree with lagos that this issue is not that crucial and should not be that big of a deal for most future swappers, specially those who plan on staying on or below 14psi for awhile. reason i say this is i dont really know anyone who has had any issue with the stock rail on upgraded pump... be it celica, mr2, camry, or whatever car a 3sgte has been swapped into.

i dont at all.
by the time you realize the problem, theres a big hole in the side of your block.

edit: on a side note...i agree with lagos that this issue is not that crucial and should not be that big of a deal for most future swappers, specially those who plan on staying on or below 14psi for awhile. reason i say this is i dont really know anyone who has had any issue with the stock rail on upgraded pump... be it celica, mr2, camry, or whatever car a 3sgte has been swapped into.

[jgreening]

A new rail is necessary on TUNED engines. If you are running the stock ECU, the leanest cylinder on the stock rail is still pig rich.

I asked a similar question in their original thread a long time ago and the Wolfkatz's could not say there would be a problem on the stock rail and ECU even with an upgraded pump. Check out posts 87 and 88 in this thread:

Fuel Rail Thread

I have yet to see someone having a problem at 15psi on stock injectors, stock rail, and upgraded pump.

This post has been edited by jgreening: Feb 5, 2006 - 9:59 AM

[BBoYRuGGeD]

A new rail is necessary on TUNED engines. If you are running the stock ECU, the leanest cylinder on the stock rail is still pig rich.

I asked a similar question in their original thread a long time ago and the Wolfkatz's could not say there would be a problem on the stock rail and ECU even with an upgraded pump. Check out posts 87 and 88 in this thread:

Fuel Rail Thread

I have yet to see someone having a problem at 15psi on stock injectors, stock rail, and upgraded pump.

thnx jay...yah i was thinking myself "why would it be leaning?" when the ecu dumps a crackload of fuel after 12psi to prevent detonation. im not doubting theres a pressure drop...but i dont believe this will lean anything out to dangerous levels. still tho...75 bucks is still pretty cheap for an upgraded rail from ATS

bboy

[jgreening]

A new rail is necessary on TUNED engines. If you are running the stock ECU, the leanest cylinder on the stock rail is still pig rich.

I asked a similar question in their original thread a long time ago and the Wolfkatz's could not say there would be a problem on the stock rail and ECU even with an upgraded pump. Check out posts 87 and 88 in this thread:

Fuel Rail Thread

I have yet to see someone having a problem at 15psi on stock injectors, stock rail, and upgraded pump.

thnx jay...yah i was thinking myself "why would it be leaning?" when the ecu dumps a crackload of fuel after 12psi to prevent detonation. im not doubting theres a pressure drop...but i dont believe this will lean anything out to dangerous levels. still tho...75 bucks is still pretty cheap for an upgraded rail from ATS

bboy

Its your money. If it were me, I would wait until you get an EMS and then buy a real rail from either Wolfkatz, Hux Racing, or Speed-Source. I like ATS and they provide very good products but I would never buy one of those rails.

[BBoYRuGGeD]

Its your money. If it were me, I would wait until you get an EMS and then buy a real rail from either Wolfkatz, Hux Racing, or Speed-Source. I like ATS and they provide very good products but I would never buy one of those rails.

my thoughts exactly...i was gunna wait it out 'til i upgrade the entire fuel system originally until this topic came up. i havent had any input from anyone who actually has experience w/ the ATS fuel rail so far...so i may just wait it out like i originally planned. Wolfkatz sounds good to me, but out of curiousity why wouldnt u buy an ATS rail Jay?

bboy

[lagos]

i dont at all.
by the time you realize the problem, theres a big hole in the side of your block.

lol, and how many mr2 guys have you seen this happen to, on the stock turbo and injectors? there are TONS of 3sgtes with well over 100,000 miles on them, still running ritch after many years of use.

A new rail is necessary on TUNED engines. If you are running the stock ECU, the leanest cylinder on the stock rail is still pig rich.

yeah, i totally agree.

I like ATS and they provide very good products but I would never buy one of those rails.

i also agree. their rail is basically just a stock rail, that has one hole drilled out bigger to try to fix the problem. if you are really worried about fixing this possible "problem", then buy the 300$ wolfkatz rail that they offer.

This post has been edited by lagos: Feb 5, 2006 - 4:50 PM