You can always get rid of the surging (flutter) by shifting down. In general, it is very hard to get the turbo to surge if the engine is runnig over 1700rpm. As the volume of air flowing through the engine goes up, the compressor map widens a little bit, and you can run at higher boost's without surge. So, how annoying it is depends a lot on fueling and driving style. Dave also drove through the surge for a while, I believe, before he swapped over to a wh1 with MWE slots, so they don't necessarily break right away if you let them surge a little bit.

 

thanks for the info, alec

 

My old stock h1c with the 18cm. would surge like crazy.I drove it like that for quite a while.It never broke.Just makes your truck sound like a piece of junk when it starts doing it!

 

What Alec said. It's irritating but not really a driveability problem. I noticed better response in the RPM range where the flutter would occur once I changed turbos, but it was never bad to drive.

 

cool, thanks! anyone got a 12cm housing for sale


btw, how would I trigger the wastegate?

 

Check the classifieds for ones for sale. They come up on Ebay a lot, too. You could also put in a "wanted" classified ad.

There should be a wastegate actuator attached. It will need to be supplied with boost. All I did was put in a tee on the port I ran my boost gauge off of, put in a hose barb, ran a 5 foot section of 1/4 steel hard line under the motor and connected it at both ends with fuel hose. Did it last Sunday, as a matter of fact.

Prior to that I was running a TurboMaster wastegate actuator. No plumbing required for that one, but boost was out of control with the water/meth. The stock actuator opens the wastegate farther which let me get out of the 40 psi range. It's a nice unit because you can adjust your boost with a 1/2 inch wrench, it just was overwhelmed by the water/meth and the POD's.

 

hmmmm, forgot about the TurboMaster. All else being equal, will the 12cm cool me off since it should provide more boost at lower revs, or, since I'm non i/c, will I just have more heated air at lower revs? at 65 in 5th I'm seeing 3-4 psi and maybe 650 post or so---if I mat it at 50-55 in 5th, it lags for 1/4 second or so then hits a solid 31 psi and pulls like mad till I get skeerd! Can I improve on this with the 12? On long gentle hills, the egts climb but never really become stable---the grade usually ends before I hit 900 post. Sorry for the ramble--just trying to give as much detail as I can.

greg

 

I'd expect to see lower EGT at low RPM under load. Your temps don't sound bad to me.

The boost doesn't become "hot" boost until you get out of the compressor's effieciency range - which is why you need a wastegate with the 12 cm. You'll want to keep the boost down around 25 psi - unless the EGT gauge tells you 30 is better.

You can expect zero lag when you floor it at 50 mph.

 

TOO FUNNY!!!! I get the same reaction from people when I tell them I'm running a 12cm! Some of them were even from this board! I also saw a big drop in EGTs when I moved from the 16cm to the 12cm and it doesn't hurt my towing ability at all. In fact it improves it because beacuse the EGTs are lower.

BTW I have my wastegate welded shut. I hit a max of 32# of boost and my EGTs have never gone over 900*F with the 12cm. This is with a 10ft camper on back pulling a 4000# Jeep thru the Rockies. With the 16cm I would have to back WAY off the pedal to stay under 1000*F.

 

Same numbers here. I use my wastegate at 24 psi. I used to run it 27 psi, but now with the drilled divider and dropping to 24 I can feel a slight increase in acceleration. Best analagy to use is it feels like turning loose the reins on the engine on the last 500 rpm til governor cut-off. EGT is still good and just a slight haze when accelerating. Towing, the torque is much more abundant below 2000 rpm, almost like there's a such a high torque curve down there that the weight can't overcome. I'm just waiting for the Getrag to split into two

 

You need bigger injectors, Clay.

 

Ya, but then I'd need a bigger turbo, more tranny mods......