can I get away with an 18g now?

[ryboj]

I realize the whole upgrade path, and with a larger aftermarket turbo it's best to have available fuel and a tuning device (among other things).... however I also know on a slightly larger turbo upgrade you can get away with having a larger fuel pump and keeping the boost low if the budget won't allow for the other toys at this time.

Also, I know the stock SMIC is pathetic in many ways and has its limitations quite early in the game, but it can be sufficient again for low boost. I do realize it will heat soak after a few shifts on a hot day.

Question is, can I get away with running an 18g on stock injectors/SMIC at 14 or so psi? I would feel comfortable running a BigT28 on stock setup, but the 18g flows more, so I really need some confirmation I can or can't.

I would also install a 3" turbo back as an FYI before the turbo install.

If I can run the 18g on the stock injectors/SMIC, will the gains be very marginal over the t-25 or will there be a difference? Basically will it even be worth it if I can't turn up the boost? If it is a bad idea, I'll just not do anything until I can afford one day to do it right and add the injectors, tuning device and larger IC first and foremost.

 

[Mike1992]

It can be done, but I would lower the boost less than 14psi. Although not smart, a data logging program would be wise. I run a tdo5h 18g at 12psi and feel safe but I have no logger as of yet so I keep the boost down. I had it set at 10 psi but the exhaust raised it to 12. 12 psi on the 18g vs 15psi on the t-25 will be a dramatic difference. A t-25 at 20psi prolly wouldnt be pushing close to what an 18g at 12psi would be so I say go for it, keep the boost low until you can log and tune.

 

[arash15]

u can set ur boost on the t25 to 16lbs. after that its just blowin hot air. i'd look into supporting upgrades before jumpin into a bigger turbo. here look into this ...http://roadraceengineering.com/2gupgradepath.htm

 

[ryboj]

Mike, thanks for the first hand experience. Sounds like you have it dialed in around 12psi now. How does the 18g feel at 12psi compared to whatever boost level you previously ran the t25? In your mind, is it worth having an 18g at the lower boost setting until I'm able to do the rest of the mods? I like my t-25's low end feel, but it falls off immediately...with no mid or top end. Get up and go on the freeway is descent, but it's a very short blast. I'm hoping the 18g will take me a little further for the time being until I can have everything else in place. Can you explain the low-mid-top end pull you're experiencing now with the 18g when compared to the t25 you had?

I just purchased a datalogger for nowadays, and I'm pretty much settled on buying an 18g. In time, if things work out, I will avoid the safc/logger combo and go straight to DSMLink.

arash: Thanks for the 2g upgrade path. I'm quite familair with the upgrade path, I'm just trying to see if I can bypass it by running a low boost setting until I can purchase everything else, that's all.

Interesting enough, RRE said in the upgrade path:

"OK, now you really need a turbo. With the turbos up to the the 18-G, you can keep the boost down and need only an upgraded fuel pump. To run over 15-16 psi boost on pump gas safely, you will need more fuel. Even at 13-14 psi, these turbos will all blow away the T-"Too Small" Garrett at 16 psi."


That's good to know.

 

[Mike1992]

Well, I have a 1g so I had a 14b stock which is a better turbo than a T-25 to start with. From what ive read, no first hand experience the t-25 drops off boost around 6-6.5k but the MHI turbos such as the 14b/16g/18g/20g all pull to redline and beyond if your motor can handle it. I really dont have another turbo to compare to however I bought my car with a locked up 14b and replaced it with a ported 18g. But compared to friends of mine, it greatly outpulls my buddies 91 gsx on a small 16g at 15psi by far. If you go with the 18g your boost will come on a little later but you will pull all the way to reline without any drop off at all. I get full boost of 12psi at about 3200rpms with a few minor boost leaks. You can choose your boost level which is safe to you with a logger just dont get the idc's beyond what the motor cant handle. Good Luck

 

[ryboj]

Duh! I don't know why I forgot you had the 14b originally. I have the t25 stuck in my head, and I'm trying to do anything to get rid of it.

The reason I think I've finally come to want the 18g is because it flows more than an Evo3 but not as much as a 50 trim or 20g, and spools up a little later for my FWD application. Kinda in between, so I think it will work for me.

It's good to know that 18g pulls and pulls all the way through the RPM range. That's encouraging.

If I go this route, I will definitely keep an eye on the duty cycle. I likely won't wait long before I address all the other supporting mods to bump the boost to around 18-20. I just can't stand having this little turbo on there any longer.

Appreciate the feedback