Engine/Transmission (1994 - 1998) Which is better - turbine housing ?

[Matthug]

Just wondering if a non wastegated 16 cm housing will still flow more or not if I drill and port the stock 12cm housing. I'd like to have better highway EGT's, running 800 on flat ground at 70 MPH is pretty high and 1100 up any decent grade empty but I'll live with it if the top end flow of the 16 is still better than a drilled and ported 12. Don't have money for a 14, saving up to buy my brothers HX40. Although my EGT's stay down a lot more if I use the valet switch, but I like to have power on tap in case a powerchoke comes up on me or something.

 

[WDimig]

if you already have the 16 housing in your truck, youll see no benefit from drilling the 12cm housing, other than more boost, but youll be chocking the turbo even more, i would suggest saving up for a HTB2 witht the 12cm housing, it flows more air, and spools just as fast, if not faster, youll have better top end power, and the nice thing about those turbos is you have room to grow with your engine mods, if you need more air, send the tubo in and have either a bigger compressor installed, or the bigger 14cm housing, ive got the SP 66/14 on my truck and it's still a very responsive turbo for the size of the turbo, and i have no problems spooling it, although it is not very well suited for towing which i do not do with this truck.



wes

 

[Cooker]

If you are looking to do nothing but lower your highway EGT's going back to the 12 housing may do that. Your peak EGT's will obviously be higher and you may notice a loss in top end performance.

 

[moparguy]

My take is a bit different from Wes'. I ran a 16 for a few years, never really liked the slow spool when pulling a load (backhoe, loaded horse or hay trailer) and trying to start off on a hill.



A few months ago I gasket matched the 12cm housing, porting back a 1" or so into the housing. I then drilled the divider out to 1 1/16". I found a 1. 25" exhaust valve out of a junkyard engine to replace the stock wastegate valve.



Last I tightend (shortened) the waste gate adj. rod a bit.



Now I have better spool, boost doesn't exceed 35lbs. (with the 16 would hit 45+) and egt's are down 100+ degs. Still can go above 1250, but it's much slower.



I'd recommend the above, takes a bit of time, but no cash and if it dosen't work try something else.



Good luck, RR

 

[WDimig]

that would work, but his compressor is not big enough to support the amount of air he needs, look at his sig. you need better flow on the exhaust side, but at the same time you need more air, matt is throwing a decent amount of fuel at his engine, and would benefit both a compressor uprgrade as well as exhaust.



wes

 

[moparguy]

I had my settings on PDA due to a dialup connection. On that mode you don't see sigs. But now I do. I agree, need more air in. Lots of ways to get there.



I'm ok with my current setup untill I go out west to the Rockies, then barking the turbo becomes a problem (with the 16). I suspect it'll be worse with the ported 12.



Wes, any 1st hand knowledge on the HTB2/12 combo towing at high altitudes?



To keep barking down I had to really spin things up when pulling big hills with the 16housing.



RR

 

[WDimig]

the only barking that ive ever heard of was with the 64 & 66 wheels due to the size of the wheel, i heard nothing but good comments on the 62/12 combo, spools very fast, and keeps things cool, like i said, my 66 still spools very fast, but it will surge alot if i towed with it, shouldnt have that problem with the 62/12 setup, or even the 62/14, would provide more top end breathing room, and i doubt the spool up difference would be noticed. i had an issue with barking and surging back when i had the 64/12 setup, i had the K&N FIPK air intake and wasnt happy with it, i went and bought a AFE PG7 stage II setup and it cured 80% of my barking problem, could never figure out why, the only thing i could think of was the air flow was now different than it was the the K&N setup. i think that the 62/14 setup would be a great turbo, and i noticed you were looking to buy a used hx40, i think the HTB2 is a much better turbo than the 40, maninly because it can be upgraded when you need it to be, and internally it is much stronger and better built.



wes

 

[Matthug]

that would work, but his compressor is not big enough to support the amount of air he needs, look at his sig. you need better flow on the exhaust side, but at the same time you need more air, matt is throwing a decent amount of fuel at his engine, and would benefit both a compressor uprgrade as well as exhaust.



wes

I know, thats why I'm gonna go with my brother's HTT HX40... but thats not for like a month. I'm not interested in any HTB2 turbo's because I cannot afford them. My brother is getting a sled puller for his so I'm buying his HTT HX40 for $600. I only plan to have 400 RWHP and thats it so the HX40 is perfect for me, I want something like DD3 injectors and I'm done with BOMB's. Without his TST comp box on he has 400 RWHP in an 02' ETH, he drove my truck with the 16cm HX35 and said I will have no trouble spooling his HX40 whatsoever at even the power level I'm at now in fact in may spool it faster. He said 12v's spool turbo's better than 24's, but he still calls my truck undervalved.

COOKER- I'm not comparing a straight 12 and a 16 housing here, I'm comparing a drilled and ported 12 to a 16. I know if I put the 12 back on with leaving it alone thats quite apparent it will flow less. The whole basis of this thread is asking if I port the 12 will it flow close enough to a 16 non wastegated to not make a seat of the pants difference in the upper RPM's. I only have a 3KGSK not a 4, so bear that in mind please.

 

[Matthug]

My take is a bit different from Wes'. I ran a 16 for a few years, never really liked the slow spool when pulling a load (backhoe, loaded horse or hay trailer) and trying to start off on a hill.



A few months ago I gasket matched the 12cm housing, porting back a 1" or so into the housing. I then drilled the divider out to 1 1/16". I found a 1. 25" exhaust valve out of a junkyard engine to replace the stock wastegate valve.



Last I tightend (shortened) the waste gate adj. rod a bit.



Now I have better spool, boost doesn't exceed 35lbs. (with the 16 would hit 45+) and egt's are down 100+ degs. Still can go above 1250, but it's much slower.



I'd recommend the above, takes a bit of time, but no cash and if it dosen't work try something else.



Good luck, RR

Thanks for the idea, but I do not have a welder nor do I know anybody that has one readily available for me to use.

Wow I only run 34 PSI with the 16 cm housing, bumping the timing from 12 to 15 lowered boost 1-2 PSI. When I first bolted on the 16 I actually had an increase in peak EGT's, I think it was because of less boost. The HX35 I'm running is the stock one off my brother's 02', he was actually running 42 PSI boost on it because it wouldn't flow enough the wastegate was wide open and boost wouldn't get lower than that for him. I ran 38 PSI boost with the 12cm housing, swapped to the 16 and it ran about 35-36 PSI but my EGT's went up 100 degrees. Previously (only BOMB was a #0 plate) my EGT's would only get to 1300 on a long steep grade by my house. After the 16 housing swap it got to 1400. The only thing that would explain that is the lower boost, even though above 35 PSI is hot boost I suppose it's still boost and more air going in.

 

[zstroken]

He said 12v's spool turbo's better than 24's, but he still calls my truck undervalved.

That is the first time I have heard that.

Back on topic. I really like moparguy's idea. I would think if you found the exhaust valve and drilled the hole a local welding shop would weld the linkage back and whatever welding you needed on the new flapper for less that $30. We just hogged out the wastegate on a 12cm, but have no data to compare it to the 16. I would say give it a shot, on the hx35 off of the 98 it took like 10 minutes to open the port minus install and removal time. Let us know the results of the comparison. I am thinking about modding a charger similar to what mopar guy is saying and pulling in the stock appearing charger class.

 

[pwerwagn]

I think it could work fine. I believe about the largest you can open up the wastegate is 40mm, and thats after milling a little meat away from the wategate area.

Im planning on doing the same thing. I already have the divider ground out so that it wastegates all 6, Im going to port the extra 12V manifold, and Im going to mill the wastegate and replace the flapper with a larger one.

I have some pics of my idea that someone else did, lemme see If I can find it... .



-Jeff

 

[pwerwagn]

here is one pic.

--Jeff



*edit* never mind, it didnt load. I gotta shrink it. I will do it and post later...

 

[Matthug]

How big is the stock flapper? 1''? How big is the stock wastegate hole?

 

[Matthug]

Hey guys just an update. I ported out the housing today, since I ran that housing on my truck before replacing it with the 16 I had a perfect way to port match... . the soot! I was shocked, it was about 3/8'' of each volute on the outsides that needed taken off and blended in and about 1/8'' on the top and bottom. I ported the wastegate hole, the max I could take out was about 1/8'' all the way around with the stock flapper. But 1/8'' is pretty much, obviously equals out to 1/4'' larger hole size.

I still have a question though, I cut the divider out about 3/4''. Is this enough or should I go more? I need to know before I go and install this on my truck hopefully tomorrow.

 

[pwerwagn]

In my opinion, 3/4" is not much. Im not sure if that is enough to equalize pressure between the 2 volutes or not. I think I'd go 1-1. 5" or so.



Did you just use a dremel to remove the material on yours?

 

[Matthug]

OK.

I use an air die grinder with carbide bits, then dremel with sanding disks, then I put a wire brush on the die grinder and polish it all out. I used to port the stock log type exhaust manifolds for 2. 2/2. 5 front wheel drive cars, did it as a hobby on the side... . I was building quite a reputation that even one of the biggest vendors (Chris from Turbo's Unleashed) called me up asking if I wanted to port for them! Friend of mine did some testing on it for flow, he tested a stocker, one from Forward Motion, and mine, and mine kicked forward motions azz! I was pretty happy about that, that thread on turbododge.com really boosted my rep.

I've never worked with twin volute turbine housings though, so I have no experience there and thus the purpose for this thread! Thanks so far for the help. I forgot to take my camera down to snap some pics and get opinions because I still have a couple more questions. I talked to my brother, told him that I put a bevel on the center divider but he said that it should be flat even though it's back in there. Also, where the center divider is attatched to the top and bottom, should I grind that down to the point where it shouldn't even look like there is a divider there? Kinda hard to explain without a pic. I just shaped it in, the whole thing looks kinda like a half moon but I'm wondering if it should look more like a rectangle (from a side view). Man I wish I didn't forget my camera LOL.

 

[Matthug]

OK, finished porting it today... ground it back in about 1'' and flattened off the top and bottom. Any opinions? Should the divider in the middle be flat or beveled like I have it? I didn't get it perfectly straight, but it looks worse in the pic than it does in real life.

 

[DSahd]

looks like you have a crack on the top side of your pic.

 

[Matthug]

No the die grinder got away from me, I sneezed and it went up over the flange taking some metal off with it LOL. I'm gonna get the flange surfaced before installation.

 

[JPittinger]

Do you have a link to the thread on turbododge.com?