12cm turbo is in the mail.....

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I suppose now is the time to build the 4" exhaust. Isn't the outlet on the 12cm turbo considerably different than that of my 18. 5cm turbo?

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http://coffeewithJesus. homestead.com/web1.html 89 1-ton, K&N, cleaned up exhaust, Dynomax straight-thru, rebuilt pump, intercooler, louvered fenders, 93 aftermarket smoothe grille; 78 35'Avion. Jesus saves!

 

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Just made the change from 18. 5 to 12. Used the same pipe that I had with 18. 5. You may have to shorten the pipe at turbo some if there is a clearance prblem with firewall components. Im running 3" open with great results... 30 psi.

 

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Thunderolls,
Doesn't the smaller housing raise EGT's?
Matt


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90 W250, 5-speed, 3. 54 gears, 16 cm2 housing, tach, pyro, and boost gauges, K&N air filter.

 

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Hello fellow First Gener's!

I too have been bitten by the urge to try the 12cm2 wastegated housing on our First Gen trucks after visiting with Ted Jannetty. Ted mentioned that the 12 really wakes up our VE injector pump equipped trucks because it builds more boost at all RPM's which provides more O2 for complete fuel burning in the cylinders. Power Wagon has also mentioned the 'snappy' nature of the 12cm2 equipped First Gen's in HVAC's posting in our forum.

Ted mentioned that he has dump substantial fuel through the 12cm2 without any EGT troubles. He mentioned that you have to remember that you're actually cramming more air into the cylinders providing a cooling effect at all levels of operation over the other housings, this helps to lower EGT's.

I have also talked with Joe Donnelly extensively in my quest for a used 12cm2 an he is against this modification. He states that the 12cm equates to a 1 1/2" opening and becomes the restriction in the exhaust raising EGT's with increased fueling.

I believe that both Ted & Joe are correct in their own applications. Ted enjoys the off idle torque increase associated with the increased boost of the 12cm2 for towing and working the beloved Cummins. He is not looking for the top end performance that Joe Donnelly and others are that are pushing massive amounts of fuel through the engine with a Bosch P7100. Joe stated that the likes the 16cm2 for most applications but prefers the 18. 5 for more 'earnest' fueling adventures.

For me, I'm going to do a bit of experimenting and see which I prefer best. My truck came equipped with the massive, no boost 21cm2 housing and was switched to the 14cm2 after a month. Now it's off to the 12cm2 camp for comparision purposes. I also have been fortunate enough to spend some miles in an identically equipped truck with the 16cm2 housing over the last month to base my decisions on.

I guess it depends on how you use your truck and what your looking for in a power curve. Quick & snappy with a clean burning exhaust VS slightly sluggish down low with smoke and a "great kick in the pants up top". I believe with the limited fueling our VE pumps and the 12cm2 housing is going to great combo.

Thanks for the suggestion Ted & the technical help Joe!

Besides if I can't beat my girlfriends 16cm2 equipped truck I'm just going to make mine completely different to be unique once again. I still haven't figured out how "Old School" made that truck run so well!

Ps: don't forget to tighten up the AFC 'star wheel' after installing the 12cm as not to over fuel in the midrange due to the increased boost. This will also preserve MPG.

Just what others have told me in my quest for the perfect First Generation... ..... Keeno

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1992 W250 5spd. 3. 54 gears, LSD, JRE enhanced VE Injector Pump, BD High Output Injectors, Banks "Stinger Plus" consisting of a 14cm2 wastegated housing, 3 1/2" JRE modified exhaust/muffler, pyro/boost gages, K&N, Skyjacker 2 1/2" front suspension lift to clear 305/70R/16 Goodyear MT's, Mag-Hytec, Amsoil

 

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Thanks Keeno; I'll remeber to retune the pump. But the question of 4" exhaust still remains. I've got the stock exhaust with a straight through Dynomax 3" muffler now.

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http://coffeewithJesus. homestead.com/web1.html 89 1-ton, K&N, cleaned up exhaust, Dynomax straight-thru, rebuilt pump, intercooler, louvered fenders, 93 aftermarket smoothe grille; 78 35'Avion. Jesus saves!

 

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IF you REALLY wanna go, the 1st gen trucks gotta have big injectors.

They make a night/day difference in how it runs.

 

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WHICH big injectors? there are a lot of marine engine shops down here. Weren't there some 300 hp marine versions of the 5. 9?

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http://coffeewithJesus. homestead.com/web1.html 89 1-ton, K&N, cleaned up exhaust, Dynomax straight-thru, rebuilt pump, intercooler, louvered fenders, 93 aftermarket smoothe grille; 78 35'Avion. Jesus saves!

 

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Jsimpson. Have a look at the topic "Research prodject for all you injector gurus" posted by me on 6-19-00, 1st gen forum. Also search back and read "A hot 1st gen truck". This is where it all started, and the now famous PW injectors were born. #ad


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'93 W250, LE, CC, 4x4, 5spd. , Cummins, K&N, 16cm turbo, High flow Bosch injectors, Professionaly rebuilt and calibrated pump, straight exhaust, Lund visor w/lights, 5th wheel, Gooseneck, H. D. rear hitch, Aluminum everything. My Rigs

 

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Hey Jsimpson!

Have you found an intake hose big enough to fit the your new 12cm2 equipped turbo yet?

Just curious on how the project is progressing... ..... Keeno

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1992 W250 5spd. 3. 54 gears, LSD, JRE enhanced VE Injector Pump, BD High Output Injectors, Banks "Stinger Plus" consisting of a 14cm2 wastegated housing, 3 1/2" JRE modified exhaust/muffler, pyro/boost gages, K&N, Skyjacker 2 1/2" front suspension lift to clear 305/70R/16 Goodyear MT's, Mag-Hytec, Amsoil

 

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Let me clarify my recommendations a bit. The 12 cm2 housing would be good for lightly fueled first gen Rams. That would include moderate turning of the fuel screw for more power. I guess the point where a bigger housing would be advisable would be in the 180-220 hp range. The 14 is another good compromise. Both of these housings are wastegated and therefore 1. 25" longer than your stock 18. 5 or 21 cm2. New they are quite expensive compared to the non-wastegated housings. Clearance to the heater box, plastic I believe, is not too good. Make sure you have enough. The 16 is a moderate but noticeable improvement over the 18. 5 and very noticeable over the 21. It has the advantage of being a direct replacement for the bigger housings.

All these housings for the HX35 turbo have an outlet just under 2. 5". I found on the dyno and street that 4" exhaust gave only 7 hp at the 380 hp level and no noticeable improvement in egt. Recently TST tried 4" on the 24 valve with an eye to selling such a system, a premium quality stainless steel muffler and pipe setup. They found 35-50 deg higher egt, 3 psi more boost and 3 psi more backpressure compared to stock. Their tests included uprated Rams with their PowerMax boxes. Go figure.

 

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The only factor I can think of is that stainless retains heat a lot more than regular carbon steel. But shoot; that should help the flow, not hurt it! Hot air flows better than cold air; I learned that 35 years ago in basic training!

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http://coffeewithJesus. homestead.com/web1.html 89 1-ton, K&N, cleaned up exhaust, Dynomax straight-thru, rebuilt pump, intercooler, louvered fenders, 93 aftermarket smoothe grille; 78 35'Avion. Jesus saves!

 

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LT - I don't know how much the 12cm may have increased EGT, because I installed guages just shortly before turbo change and tune up. I left some performance data in another thread, I believe it is "should I go to 12cm" or something... you'll find it. My EGT seems good to me but remember I am running straight tubes 3" into 4" stack... no muffler. The max I've seen it is about 950 or so. Most of the time it is right at 6-700 even towing.

 

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Thunderolls, that stack will cool it down a little won't it. Mine seems to keep those high temps. to a minimun.
How many stacks do you have, one or two?

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'93 D350 2wd Club Cab 5-speed,136,000 miles,K&N,Amsoil throughout,Borgeson Steering Shaft,Isspro gauges(Tach,EGT,Boost,Engine Oil Temp. ),16cm Turbo Housing, "My Dream Exhaust"(5" Chrome Stack)