Larger Turbo vs. EGT's?

Howdy folks, I just put another turbo on my truck and my exhaust temps have me very puzzled. My mods are in my sig and nothing has been changed except turbos. When I was on my stock turbo I could push it to about 55 psi, but my exhaust temps were only around 1600 tops. Then I went to a plain jane s300 with a ported 16cm housing, it ran hotter than the stocker during normal driving but on top it also ran about 100 degrees hotter, would make about 40 psi of boost. So tonight I installed a B-1 62-14 charger, in hopes of cooling down up top a little. Well much to my suprise I took off for my test drive and pegged my 2000 degree pyro at about 45 psi of boost. What am I missing here folks? I'd always understood that a larger turbop while it'll run hotter down low will cool better up top? Can anyone please explain what's going on here? It's got me flustered cus at this point I was honestly happier when my stocker was in.:bang

your turbo cant stay on top, or to hot to soon. need to do some tuning and then youll enjoy it.

what can I do about to hot to soon? I already have my afc back some and starwheel tight enough to where I can realy feel it n my peddle when I take off.

Pull some fuel out of it and see what happens...a 100 plate, 4K kit, and 5 x .016's could be a lot of fuel. I only run a 5 x .014 stick, and it's too much at times on the low end!

Chris

Signature600 said:

Pull some fuel out of it and see what happens...a 100 plate, 4K kit, and 5 x .016's could be a lot of fuel. I only run a 5 x .014 stick, and it's too much at times on the low end!

Chris

Click to expand...

ok I'll try that sometime. BUt what I don't understand is if I have to much fuel for a 62-14, then how was my stocker running about 400 degrees cooler?

Mod your AFC for full travel and then pull it back and put more tension on the starwheel. Also higher timing really helps the top-end EGT's...

The stocker spools a lot sooner, and doesn't let the heat get as far out of control early...the 62/14 has a little more lag, and once it finally decides to go to work, the temps are already hot, and it can't catch back up.

Or at least that's been my experience...lots of tuning is required on a 12v to keep things in check...it's not bolt on and go, and the airflow sucks with the factory cams and heads.

What RPM are you running when it's getting this hot?
Chris

wehn it got to 2000 I was at about 3000-3200 rpm, which is propbaly making it pant pretty good because of the stock cam right? Chris if this were your truck where would you put the plate at and the afc and starwheel? right now the plates full foward and the afc is just a bit past center.

On my last dyno, stock cam, stock head, and a 63.5mm/.8 A/R housing (~14cm) power fell FAST at 27-2800RPM, shortly after spooling that thing. At 3-3200RPM, you're out of air IMHO.

To start, I'd mod the AFC to allow more travel, set it back and adjust the spring to open fully at about 40psi...then bring the plate back below half forward, and see what happens. Also, if you can live with less bottom end, bumping the timing up to 17.5-18* won't hurt much, unless the injectors start spraying out of the bowl...talk to the guy who made them and see what they say!

Also, bumping the timing up could cause HG problems if you run it hard
Chris

alright chris I'll look into it.

Another thing is that now with the larger turbo your burning more of the fuel and that's causing higher egt's where as before with the stocker you couldn't burn all of the fuel off. And I'll agree with what everyone else is saying, the motor is getting hot before the turbo has a chance to spool and start cooling stuff off.