topfeed vs sidefeed

[Subie_Steve]

Sorry if i missed a thread about this. Are there any advantages of running either topfeed or sidefeed injectors? Is it true i need to buy new fuel rails if i buy topfeed injectors? I have an 04 sti. Im looking to run DW 750cc injectors, unless someone has a good reason to go with a different brand. Also how difficult are they to install? Thanks. I have some plans coming up for the STi in the next few months so i will be needing some advice.

[Kevin M]

There's no significant disadvantage, so use what your car came with.

[sperry]

Top-feeds are cheaper, and AFAIK, it's easier to get larger sizes than you can get for the side-feeds.

To convert, you would definitely need new rails, but you would also have to get a solution for the fact that the AVCS heads are in the way of the top feed injectors on the early STis (which is the whole reason the STi uses side-feeds to begin with). I'm not sure if there are other concerns, like the injector wiring or anything, but there may be.

On my car, I've got '04 STi heads and top-feeds, but I'm running a Perrin fuel rail which allows the rotating of two of my injectors by 90 degrees that gets them out of the way of the AVCS solenoids, and everything else on the car is '02 WRX.

[Subie_Steve]

Thanks for the info. I was reading the description of the DW injectors, and both the top-feed and side-feed say they will work with OEM fuel rail. Does anyone have these or know for a fact they work? Since top-feed are cheaper by about $100 i am tempted to go with those, unless i have to buy a new fuel rail.

[sperry]

Originally Posted by Subie_Steve

Thanks for the info. I was reading the description of the DW injectors, and both the top-feed and side-feed say they will work with OEM fuel rail. Does anyone have these or know for a fact they work? Since top-feed are cheaper by about $100 i am tempted to go with those, unless i have to buy a new fuel rail.

You absolutely have to have a top-feed rail for top-feed injectors. The conversion will cost you far more than the $100 price difference in injectors.

Get the side-feed DW850's, they're excellent injectors, and will be totally no-hassle drop-in on an '04 STi.

[Dean]

Make sure you get new TGV housing seals for the new side-feeds. They probably won't come with them.

There are also the modified stock injectors that might be a good option, but I have no idea how easily they tune. I think they end up being 816cc and are only about $250 to do it.

[Subie_Steve]

thanks for the advice. Side-feeds it is, with new seals. I hate to change to the topic on this thread, but i plan on getting a turbochargers.com TD06 18g turbo($1,220), a Blouch 18g XT($1,250), or the new Forced Performance 68HTA($910) all 7cm housing. They are all about the same, im just trying to decide which one is built better. And with that would 750cc injectors be efficient enough or do i need to get 850cc?

[KSpeed Auto]

Originally Posted by Subie_Steve

thanks for the advice. Side-feeds it is, with new seals. I hate to change to the topic on this thread, but i plan on getting a turbochargers.com TD06 18g turbo($1,220), a Blouch 18g XT($1,250), or the new Forced Performance 68HTA($910) all 7cm housing. They are all about the same, im just trying to decide which one is built better. And with that would 750cc injectors be efficient enough or do i need to get 850cc?

I would do the Blouch. 750cc injectors are plenty for an 18g, and definitely do DW over mod'd stockers. But if you think you may upgrade again in the future get the biggest ones you can afford. The DW are great injectors and idle like stock.

I have a good used Blouch 18g if you are interested. Not the newer XT though. I also can usually match internet pricing on DW injectors.

But regarding the 18g - it is not that much of an upgrade for an STI. I would go TD06/20g/8cm and 850+cc injectors.

[sperry]

Originally Posted by KSpeed Auto

I would do the Blouch. 750cc injectors are plenty for an 18g, and definitely do DW over mod'd stockers. But if you think you may upgrade again in the future get the biggest ones you can afford. The DW are great injectors and idle like stock.

I have a good used Blouch 18g if you are interested. Not the newer XT though. I also can usually match internet pricing on DW injectors.

But regarding the 18g - it is not that much of an upgrade for an STI. I would go TD06/20g/8cm and 850+cc injectors.

My opinion is that a TD05-20g is the ideal sized turbo for a street driven STi. No need for the lag of a TD06 to gain top-end you'll never use on the street.

I ran one on my hybrid motor WRX in the past, and MikeK's got one on his STi now.

[KSpeed Auto]

Originally Posted by sperry

My opinion is that a TD05-20g is the ideal sized turbo for a street driven STi. No need for the lag of a TD06 to gain top-end you'll never use on the street.

I ran one on my hybrid motor WRX in the past, and MikeK's got one on his STi now.

I've driven Mike's car. I guess if all you care about is spool or you are autocrossing then go TD05. The last TD06/20g/8cm I tuned hit 20psi by about 3.5k at 5000' elevation and held it out to redline. Like any bigger turbo, you have to adjust your driving to take advantage of the powerband.

[Subie_Steve]

Ok, cool there is a lot to think about. The only thing is, if i were to run a 20g do i need to upgrade my intercooler? As of now i am on stock intercooler. I also have stock internals. That's the only concern is that i am going to buy way more parts and money then what i originally planned. My goal is for about $2500; buy injectors (approx $600 minus $160 if i send in my old injectors), fuel pump (approx $90 including install kit), Tomei Up-pipe and unequal headers ($720), custom tune at GST ($500), Turbo (approx $1200). Then install on some items since i dont know how to do it.
Do you guys even think it is worth getting headers? They are expensive and i actually hear a lot of bad things bout the aftermarket ones cracking. I need a new up-pipe since my stock one rattles and annoys the **** out of me so i figure replace it, and while thats out why not do the headers as well... But if i dont need headers that gives me $500 back to spend it somewhere else. Once again thanks for the input.

[sperry]

Headers are probably not worth the cost IMO. Better to leave 'em alone, or port/polish/coat them.

And I should think you'd be fine w/ a 20G on a stock STi intercooler if you're running a smaller hot-side like a TD05. You're not going to be making the big top-end flow that needs the big intercooler. I know MikeK's got a stock STi intercooler... which he switched back to from a big APS FMIC when he went from the GT52 to the smaller TD05-20g.

[Dean]

Skip the headers other than considering a GrimmSpeed crossover with or without P&P the stock castings. Uppipe rattle is likely just the heat shield tack weld having failed (Common problem) and is a 5 minute fix by a welder.

Only wrapped headers really crack. If you really want to try some UEL headers, I have some "MadDad" branded, GT Spec II/Tomei/XXX brand (they are all the same) with uppipe you can have for $200. No cracks and they make good power higher in the RPM range. Here is a Nasioc thread with a review, Dyno before and after, etc..

Stock internals will last 100-120K or so on a Cobb stage 2 tune with some track use. A lot less with ANY detonation. The biggest killer of the stock internals is detonation that breaks the second ring land on the pistons. Run a conservative tune no matter what you do and budget that you will have to rebuild/replace the short block at some point with one with forged pistons.

You might also consider Paul@DBTuned(Dyno Sac) or Matt@KSpeed(Local Sparks) for your tune. Both are probably a little more conservative and cheaper than GST and closer for changes/mod changes.

[Subie_Steve]

ok cool. Yeah i was thinking about it a lot and i agree i don't think headers being a $600 part is worth it for the amount of gain i would maybe see. With that said i am probably gonna buy the invidia up-pipe since i have invidia DP and exhaust. And about the turbo, there are many brands out there that make a TD05-20g turbo which company would you say has the best track record of having reliable and good performing turbos? also if i got a turbo with a 8cm housing rather then a 7cm housing do i need to modify things more? sorry i know this is a noob question.

[sybir]

Honestly? Pick a tuner and get their opinion before you start throwing parts at a car. Matt has been more than helpful so far - I'd recommend listening to him and giving him a chance to get you set up with a group of parts that are compatible and fit your needs. I've seen *way* too many piles of parts come in that aren't oriented towards a cohesive goal, and it kills drivability and reliability, with all sorts of weird compromises.

Put another way - with the amount of (valid) questions you're asking, you might be better off working with a tuner who will help you accomplish your goals then trying to figure it all out on your own. Too many people see shame in going to a shop for guidance - why not work with people who have hands-on experience with multiple setups?

[WRX06TR]

Originally Posted by sybir

Honestly? Pick a tuner and get their opinion before you start throwing parts at a car. Matt has been more than helpful so far - I'd recommend listening to him and giving him a chance to get you set up with a group of parts that are compatible and fit your needs. I've seen *way* too many piles of parts come in that aren't oriented towards a cohesive goal, and it kills drivability and reliability, with all sorts of weird compromises.

Put another way - with the amount of (valid) questions you're asking, you might be better off working with a tuner who will help you accomplish your goals then trying to figure it all out on your own. Too many people see shame in going to a shop for guidance - why not work with people who have hands-on experience with multiple setups?

Agreed! Plus it doesn't get any better than having a local tuner like Matt at KSpeed with helpful information. The shop rebuilt my car and has had nothing but great advice. Have a chat with the guys at the shop to decide direction And goals.

[Kevin M]

To echo that, figure out exactly what you want from the car, and work from there. Matt is more than happy to help you sort that stuff out, even aside from the ability to sell and install the parts for you.

[Subie_Steve]

i am in the process of talking with Kspeed. Thanks. Once everything is complete i will let everyone know how things turn out.

[03wrxwagon]

topfeeds also go to a higher cc like 2000cc

[Kevin M]

Originally Posted by 03wrxwagon

topfeeds also go to a higher cc like 2000cc

Which would be an utterly ridiculous, full race drag motor. Not really in play for this discussion. Even on E85 you can get side feeds to cover streetable power.