I sort of inadvertantly tried to hijack another thread, so...

first, i just want to hear everyone's opinion on this.

so, what's wrong with the 18g turbo? GReddy claims that the tdo5h-18g is the best possible upgrade solution to the 4g63, and i'm sure as big a company as it is, if they thought differently, it would be another turbo. it's also listed in the 2g upgrade path (http://www.roadraceengineering.com/2gupgradepath.htm) in RRE, 4th out of 5 turbo's. also my mechanic swears by it, and he was the guy worked with Injen to design the 4g63 turbo intake, he was getting custom versions from them for a while before they marketed it, and he ran the test bed for them [simply trying to qualify that the guy knows his shit, side note: thanks to Kevin and others here, i can have a little better depth in discussions with the guy, as before he would talk and i would just go 'ya, uh-huh, ok, ya, uh-huh']. anyways, he says the evo16g is not big enough, and the 20g is just too much lag for a GS-T [b/c it's FWD] car trying to get off the line, and is only suited for a GSX [b/c it's AWD]...


second, the only fuel tuning i'm running is a walbro 255, no afpr. it was installed [with near-future fuel tuning in mind] when i put in the boost controller to compensate for increased boost pressure. is this affecting performance negatively right now?

i'm getting to a crossraod right now with how far i want to push my spyder. if i upgrade the turbo, i'll surely have to do the fuel, and if i'm going to go that far with it, i'll surely do the suspension too. but really, i'm thinking of buying a GSX and swapping all my parts before i drop tons of cash into my spyder. it would be lame to pay for labor twice. i figure if i'm going to put all this work into it, and the best is available to me, i might as well do it the best way possible, right?

The 18g is kind of an "in between" turbo. There are folks that swear by it, but depending on your ultimate goals, it may not be the best choice.

In the case of turbos that are as common as the 18g and similar, I always look at how the turbo has performed in the past. The Greddy 18g has never impressed me. I have heard of one car that was in the high 11s, and that was the only one I have seen in 4 years. 16gs run 11s all day long, and the small and big 16g have both done 11.5 last I checked. The EVO 16g has already flowed 44 lbs/min on a mild setup, which is roughly what a 18g is rated for (20g is rated for ~45 lbs/min, but naturally it will be more at home at that level than the 16g) And since run of the mill 16gs are so cheap (480), even the new EVO3 16g is only 589, why bother with the expensive stuff.

I dont care how big a company is, I prefer my home made POSR exhaust over any name brand exhaust out there. ;) They are in it for the money. Its about marketing most of the time, or costs.

When it comes to big ass turbos, like my next purchase, you cant go by past performance. Even the turbo I have now is one of a kind (for sale soon too ;) ), no other data on it. So then you go on measurements, math, and theory... On small turbos, you dont have this hassle. Why try to reinvent the wheel, when the data is out there?

Not trying to scare you out of the 18g. Just providing another angle to counter your mechanics point of view (which is now yours) so you can make a well balanced, educated decision. :) Maybe the 18g has since run faster than 16gs, and I dont know about it. So you cant take everything I say for gospel either. This is my whole point. Be sure to do the research and talk to several people. Especially people that have run the turbo. Just did a search at DSMtalk in the parts review section specifically for "18g" and got this page:

http://www.dsmtalk.com/forums/search.php?s=&action=showresults&searchid=659486&sortby=lastpost&sortorder=descending

Then read this thread and look at the sig in the last post:

http://www.dsmtalk.com/forums/showthread.php?s=&threadid=100442&highlight=18g

11.96 at 114
18g


So this is a start on how you go about researching this stuff. Many poeple have run the 18g, and the info is out there. Use all the resources you have. The parts review section at DSMtalk has been around forever. Great resource. Tooners is likely to have some 18g threads too. Then get into the nasty stuff, google etc. Talking to vendors that sell it, and even vendors that dont (why?) Etc.

SO I'm rambling on and on (24 hours no sleep, and bored, lol), but hopefully its useful info for poeple just starting to look into these things...

i heard without the correct mods, the 18g can lag. you should go along with the big 16g, it spools fast and it can take some fierce horspower. The TD05h-18G turbo is good WITH the correct mods plus NOS, i think if u have the correct mods with the 18g, u'll be hittin 11s easily.

i heard without the correct mods, the 18g can lag. you should go along with the big 16g, it spools fast and it can take some fierce horspower. The TD05h-18G turbo is good WITH the correct mods plus NOS, i think if u have the correct mods with the 18g, u'll be hittin 11s easily.
Ummm, alright. Why in God's name would you need nitrous? My 20g spools around 35-3700, and I don't really consider that alot of lag. Lots of the "big" turbos don't spool until well into the 4k range. Again, the choice depends on the goals the person chooses.

My turbo spools at 4500, doesnt bother me a bit. Why? Because when it does spool it puts you in the back seat.

I think part of the problem with the greddy version of the 18g is that they use some turbine housing that is alledgedly larger than a 7cm, about a 7.5, or was it 8.5... That WILL contribute to more lag. No way around it, setup well or not. Again, if I was interested in the 18g compressor wheel for some reason I would someone like SBR or FP put it in a a regular tdo5 turbo, or basically a 14b/16g. It should also be much cheaper than the greddy version. I dont know what it goes for these days, or if its even still ridiculously overpriced, but if a 16g costs ~500 bucks, the 18g should be more than 600 or so. I can understand why this might be appealing, but not the greedy version.

My personal belief is still that the EVO 16g will mop the floor with all previous 16gs and the 18g, and approach the performance of the tdo5h 20Gs. Its still new, and just needs someone to prove it. In fact, I will be borrowing one of these turbos part way into the season just to see what it is capable of. ;) Either from a frind of mine (Joe B on the POS site) or from SBR. Naturally I'll post when I do. I borrowed a small 16g for a couple weeks and ran a 12.02 at 115 almost right away, so I expect good things from the EVO 16g on my new, much improved setup. ;)

Let me know what you think of the EVO turbo. I like instant torque, and an not sure about going BB yet. (well, late next summer, anyway)

Will new fuel delivery parts(injectors etc) be needed with the evo 16g? If so, are there any other turbos that wont need any expensive mods to boost hp

No, but to safely run the turbo at any respectable boost level; yes.

Fuel pump, 550s at the LEAST.

question what will putting 650cc injectors and a 255lb fuel pump and a new fuel pressure regulator do to your gas milage? will it affect if a whole lot..what im trying to say is will it act like a gass guzzler?
thankz
1

I suppose I should have added an AFC to that list of minimum requirements.

turbo2nr: Assuming you tune correctly, you can still get decent mileage.

Will new fuel delivery parts(injectors etc) be needed with the evo 16g? If so, are there any other turbos that wont need any expensive mods to boost hp


Its not that you need certain fuel upgrades to run a certain turbo. You need certain fuel upgrades to support a specific power level safely. ;) That being said, Lando already answered the question.

On gas mileage. The great thing about turbo cars is the turbo is only "on" when the motor is under load. So while cruisng around gas mileage remains unchanged effectively. When you start to get into big cams and manifolds, you cna see a drop. I average around 22 mpg now, but any time I floor it I am buring a gallon every half second or so, so it drags the average down. On the way to the Shootout, all highway, I averaged 28-29 mpg if I remmeber correctly. When the car was stock with exhaust/filter I used to average 31 mpg going to NC. What other car could you go from 15s to 11s and only lose 2-3 mpg? ;)

stock i was getting 240-250 miles per tank. after all the mods, i get 220-240 depending on how often i step on it. i made a 300+ mile trip all in 1 tank, all crusing on the highway before too.

Going to NC fairly stock I was getting 450 to a tank, but that was pushing it. 450 miles divided by 15 gallons is 30 mpg. My POScort now gets ~370 miles to a tank, but it only takes 10 gallons. In fact going down to SBR with two 4g63s in the hatch I still averaged 35 mpg. 38mpg coming back empty. Going to be a shock to the wallet going back to the GSX thats for sure :biggrin:

so we got a 15 gal. tank? i thought it was 14 cuz the closest i thought i came to running out [light was on for a while], or so i thought, i still only put in like 13.6 gal. of gas.
just for kicks, how much is gas out there? it's about 1.88 for 91 union 76 local to me [last time i filled it up, and that's like twice a week]

2g should have a 15.9 gallon tank, not sure about 1g. I empty my tank at the track to run race gas, so I can get a very good idea of how low we can run it and still have the pump pick up fuel. Low 15s is the most I have been able to get in. I dont think you can really pick up that last half gallon or so. And thats actually pretty good to be able to get down to within a theoretical half gallon of empty.

I'm not sure what the 93 is out here now. I've been driving the POScort for a couple months now while I redo the DSM, and it gets regular grade 87 for 1.55 a gallon :icon16:

you guy's still have 93!!?!?!?! WTF!!! fuckin' so-cal... they took it away from us a while ago, i thought it was a country wide thing... :banghead: those bastards!!!... on a similar note, do octane boosters work???

How much can a 20G flow hp wise? and how much can a 18G flow hp wise?

We can actually get 94 octane at some stations. I usually avoid it though because theres no telling how old it is, notmany people would be using it.


You cant "flow" HP, but we'll use the 1 lb/min = 10 HP rule of thumb. BTW, I find that this gives HP at the wheels for the most part. The 20g will flow up to ~45-46 lbs/min, giving you 450 wHP. The 18g flows 42 IIRC, for about 420 whp. The regular 16g will flow up to 40 as measured on my own car, so as you can see the 18g may notbe much of an upgrade. But I have never persoanly ran one to see what it flows. The EVO 16g has been logged at 44 lbs/min.

Sorry about that, i ment to say, how much power can the turbo suport, and that is directly related to the amount the turbo can flow.

But thak you very much.

No problem :) I knew what you meant.

My friend had the 18g... Cost more than a 16g... But ran more like a strong Big 16g turbo... Wasnt really happy with the money he paid for it .... compared to that of a Big 16g and thats kind of the why a lot of people said its not worth it..Might has well go bigger if you want more power... of Big 16 if you want something worth the money..