Official Interest In COBB Flex-Fuel for the Legacy GT Platform - Please speak up

[cpx4656]

I've ordered the kit now, should be here next week. But I still need to install the top feed fuel rails and lines from ID... I can't find a guide anywhere on it. I hope its not as hard.. but one awesome thing is Christmas came early this year haha

[LeGiT_Flat4]

I plan to convert to top feed as well but I'm curious about whether or not it's absolutely required. Dave mentioned that it is in over in the Cobb Flex Fuel and You thread:

 

Injectors are needed for flex fuel and we always suggest the Injector Dynamics 1050X injector or COBB 1050X injector. If you have a 05-06 Legacy GT or 04-05 Forester XT with sidefeed injectors you will need to convert to top feed fuel injectors. These are also available on the website in our signature below. These 1050X are specifically made for alternate fuel use like E85.

 

But I can't find any mention of that on Cobb's website. In fact, looking through their installation guide I can see what appears to be yellow side-feeds in a couple of the pics on the car they are installing the ff kit on.

 

 

Dave, is the top-feed conversion requirement for 05-06 LGTs your own in order to get a flex fuel tune from you? Or am I missing something from Cobb. I get all the reasons to do the conversion along with the higher capacity fuel pump but I'm just curious if it's outright mandatory because right now I run e85 full-time with 850cc side-feeds and I've had no issues. Besides, installing upgraded side-feeds is a pretty easy job compared to the top feed conversion.

[Somac]

Top feeds are not required. However, the injector choice with side feeds is pretty terrible and not many tuners like tuning side feed injectors, not to mention that once you get to a certain level (1000cc+), you literally have no side feed options.

 

If you know right off the bat that you're planning on going E85 and making at least 300whp, you should just do the top feed conversion with 1000cc or higher injectors. Otherwise, they'll hold you back.

[rebourne]

I had 850cc DW side feeds ( hit me up if you want them, lol), and with a VF52, ELH and E85, the injectors were the limiting factor. I'm on ID 1050Xs with the side feed to top feed conversion rails.

 

Since the ID top feed kit is essentially the same as the Cobb, hopefully someone will come out with a how to soon. If not, I'll drop it off at my shop and let them sort it out.

[m sprank]

I love how Bigger is Better has become the norm for tuners and injectors. I recall making 400 dyno jet awhp running DW 750cc top feeds and a 7cm HTA68 on a stock long block. Using e85 for fuel.

Yes the injectors were a limiting factor. I could only hold 17-18psi at redline, not the 23psi peak. Oh darn.

 

I also recall making 500+ mustang awhp with dw 1300cc side feeds and a 42r turbo in a 04 STi running e85.

Edited November 29, 2018 by m sprank

[rebourne]

I love how Bigger is Better has become the norm for tuners and injectors. I recall making 400 dyno jet awhp running DW 750cc top feeds and a 7cm HTA68 on a stock long block. Using e85 for fuel.

 

I also recall making 500+ mustang awhp with dw 1300cc side feeds and a 42r turbo in a 04 STi running e85.

 

 

Adjustable FPR?

[m sprank]

Stock on my specb b.

 

Aeromotive on the STi, but set to stock 43.5psi at idle with no vac reference.

 

Yes it can he done. The Spec B was scary easy. The STi with custom rotated 42r was friggin INSANE. On a street pull log/test we lost the laptop out the passenger window when we hit peak boost. GREAT TIMES. Some of the best of owning my own shop. Gawd the laughs when we pulled over and recovered the still running laptop out of the weeds.

[Somac]

Most tuners don't exactly like maxing out the IDCs on a customer car or cranking up the base fuel pressure too high. It doesn't exactly leave much room for safety. Typically on E85, for 300whp-400whp, 1000cc are recommended. 400-500, 1300cc recommended.

[LeGiT_Flat4]

Agreed that there are a lot of reasons to convert but like I mentioned, I am currently tuned (by Dave) for e85 which is what I run full time on 850cc DW side-feeds with an 18g turbo and I make well over 300 awhp with IDC maxing out at about 85%...and I'm at 4400+ feet above sea level. Thus my curiosity about whether Cobb specified a requirement for top feeds. Sounds like it's more of a tuner preference but obviously there's a lot of sound logic behind it.

[m sprank]

I have never run idc higher than 92%. Even though I know you can push higher.

 

As I mentioned I also dont crank up the fuel pressure.

 

It is my experience that most tuners are requesting far more injector than actually required. That was my point.

 

I think my personal experience and who I have worked with developing speaks for itself. I have been working with/testing Subies and e85 since 2009/2010.

Edited November 29, 2018 by m sprank

[Somac]

It's just for safety's sake. Every kid out there is going to try to make more power than they should, and being in the tuning game, you know that the very first person that gets blamed any time there is a problem is the tuner, regardless of true fault. "My tuner is obviously the reason my car blew up when I tried to do a WOT pull in 4th gear at 1500rpm."

 

Plus, who wants to have to buy new injectors every time you want a little more power? It's better to only have to buy injectors once or twice, rather than buying 750s, then 850s, then doing a top feed and 1000s, then 1300s... It's why most tuners will just recommend 1000s right off the bat since it leaves you open to do what 90% of guys eventually do without losing too much resolution.

[m sprank]

Or the sweet spot in profit is the ID1000s and ID hands tuners valuable indepth data on the injectors making scaling easier. So the injectors get pushed to the public.

 

People are sooooo blind to the reality of life and business. Oh, and if a motor went that I built and was tuned at my shop I got blamed no matter what. I owned the shop.

[rebourne]

I currently own a set OEM 550s, DW 740s, DW 850s and ID 1050s...

 

Not sure how accurate these guy's calculator is, or what kind of dyno their "@wheels" is close to, but here goes:

https://fuelinjectorclinic.com/flow-calculator

400 @wheels on E85 = 1046cc with 90% IDC and 43.5 psi fuel pressure (FP)

 

or from the other angle, E85, 90% IDC, 43.5 FP:

740cc = 283 hp

850cc = 325 hp

1000cc = 382 hp

1300cc = 497 hp

[stocklgt]

I currently own a set OEM 550s, DW 740s, DW 850s and ID 1050s...

 

Not sure how accurate these guy's calculator is, or what kind of dyno their "@wheels" is close to, but here goes:

https://fuelinjectorclinic.com/flow-calculator

400 @wheels on E85 = 1046cc with 90% IDC and 43.5 psi fuel pressure (FP)

 

or from the other angle, E85, 90% IDC, 43.5 FP:

740cc = 283 hp

850cc = 325 hp

1000cc = 382 hp

1300cc = 497 hp

 

My 1300s ran out of fuel on E85 at about 500whp, so that looks about right. Was going to upgrade but sold the car before i could dump more $$ and fuel into the platform. I do miss it though

[utc_pyro]

There isn't really a reason to fear running IDC's into the high 90%'s or low 100%'s as long as that only happens on the coldest days you encounter. The ECU IDC peramiter includes injector dead time, so 100% is more like 94% on other platforms. I hit ~105% on my stockers without any leaning out before I swapped to DW740's. Then went form DW740's to ID1050X's not due to needing better flow, but due to having defined low pulse width correction tables while I was chasing a stumble/low speed AFR stability issue (injectors helped, but wern't the issue).

 

 

 

The published ID1000 data is excellent though, and due to their popularity most tuners have a set of maps already developed for them handling tip-in and such. Thus as M.Spank says, they are pushing everyone to them because they make their lives easier. They might sell is as safety or headroom, but in reality it just makes them more money.

[m sprank]

BINGO! The tuners are "lazy" and dont want to have to scale every set up. They already have the scaling for the IDs. Faster and easier so they make more. Then, ID actually polices their product pricing and enforces MAP. So the profit is better on the parts too.

 

Why would they recommend anything else anymore? MONEY, MONEY, MONEY, MONEY.

[hadvw]

Test - forum quirk? Shows a 17th page, but I can't actually go to it..

[Sparkey]

 

 

From about 7:30 to 14:00

[stikiller]

PE side feeds and all other supporting mods here on e85. Running like a champ for a year and a half other then a busted center diff and a most recent busted rear diff.

[lvkeith]

I would also switch back from OS if a flexfuel option was offered for my 5eat.

[Code]

Today i downloaded Cobbs install manuals for the kit and the pressure sensors. Im away from my car for a few days, so i can’t confirm any oh the questions that this raised.

 

A few observations:

 

The COBB FPR may or may not interfere with a GrimmSpeed Master-Cylinder Brace

 

The Cobb website may be incorrecttly indicating which kit is needed for the 08-09 LGTs. IIRC the 08-09 cars use a 5-pin TGV connector. I’m pretty sure that the 3-pin was only on the 05-07 cars. Can anyone confirm this for me first-hand? I deleted my TGV and wired in a lc2 and I swear it was a 5 pin.

 

* in regards to my specific setup, I’m currently using a TGV to log AFR. I will lose that ability so I will have to log it using other means. This sucks even more because I clipped a wire at the factory connector in order to hijack the signal. So I will have to repin the connector or clip the Cobb harness. *

[need bb]

I run E85 on my 850cc sidefeeds, but have to taper boost as my IDC reach 95%. With my TD05-20G, Airboy/virtual dyno shows around ~365whp. I likely leaving around 10-20WHP on the table given the lower boost.

[lvkeith]

Today i downloaded Cobbs install manuals for the kit and the pressure sensors. Im away from my car for a few days, so i can’t confirm any oh the questions that this raised.

 

A few observations:

 

The COBB FPR may or may not interfere with a GrimmSpeed Master-Cylinder Brace

 

The Cobb website may be incorrecttly indicating which kit is needed for the 08-09 LGTs. IIRC the 08-09 cars use a 5-pin TGV connector. I’m pretty sure that the 3-pin was only on the 05-07 cars. Can anyone confirm this for me first-hand? I deleted my TGV and wired in a lc2 and I swear it was a 5 pin.

 

* in regards to my specific setup, I’m currently using a TGV to log AFR. I will lose that ability so I will have to log it using other means. This sucks even more because I clipped a wire at the factory connector in order to hijack the signal. So I will have to repin the connector or clip the Cobb harness. *

 

My 09 OBXT has a 5 pin connector for the TGV. I use it for the wideband in BTSSM with a plug from a Ballenger Motorsports just in case you'd like to put it back. Could you just log the TGV voltage with the Accessport and convert it after?

[Code]

My 09 OBXT has a 5 pin connector for the TGV. I use it for the wideband in BTSSM with a plug from a Ballenger Motorsports just in case you'd like to put it back. Could you just log the TGV voltage with the Accessport and convert it after?

 

Yes BUT the ethanol sensor uses on TGV input and the fuel pressure sensor uses the other.

[Sparkey]

Yes BUT the ethanol sensor uses on TGV input and the fuel pressure sensor uses the other.

 

So then does it require a TGV delete?

 

I plan on going top feed with deletes but the way you say that makes me wonder if you have to delete them if it highjacks the signal if you werent planning on it. Just curious.