Which turbo for me?

[dpuckett]

I have had it with used/ reman turbos, so I pose the question of which new turbo to buy. I had really good service from the PDR HX35 I had on my 91, and had it not been 20deg high when I sold the truck, the turbo would be on my 92 now. BUT... ... . I saw on PDR's website the PowerMaster turbos for $100 less than the PDR HX35. It has a 16cm ex housing, 66mm impellar, and a/r ratio of . 7 .



Longevity and quality aside, and strictly from a performance standpoint, is the latter too much turbo for my current fuelling? I have 120cc, hit a peak boost of ~32psi boost, and EGT in the red. I MIGHT get some bigger injectors this summer, and I may not. If I can hit 20mpg with my current setup, I may stick with it. I like the 4" ex outlet of the PM turbo, and with the housing being smaller than my stock H1C, and the impellar being a good deal bigger, I wouldnt think overall spooling would be too bad, though it may not spool as fast as a H1C-12. I do a lot of intown driving, but would give up some MPGs in town for a couple on the highway. ( I can drive to my mom's house in a weekend and drive more miles than I do in 2-3wks intown). Keep in mind I have a . 020 over head gasket, so more air is better, and the 4" ex outlet would help in that regard as well.



On the flip side, the PDR HX35 is a known quantity, and though it cost more, the quality and life expectancy are not questioned. Bad thing is, I'll still have my big 18cm housing (for now). I also wont have to do any exhaust work to get it in there- literal bolt in. The impellar side is smaller, but I know it would fit my current set up. If I get some bigger sticks, I may be in the market for a bigger turbo before I want to spend the money again. Then I'd be out $700 for the turbo.



Aw shucks, I hate BOMBing at times. But knowing that I can outrun some of the newer trucks is worth it at times.



Daniel

 

[MMiller]

Well, I'll be watching this thread. I've backed the fuel down on mine, and still have bad surging problems, and am leaving a lot of power in the garage, to keep the pyro happy. I'd really like to see some suggestions on turbo upgrades. I'm happy with current spool up, don't mind a little smoke, but its got to breath down the interstate towing heavy.



Michael

 

[bmoeller]

A 66/16 is gonna be a laggy SOB. My HTT 64/14 spools just as well as the PDR HX40-'gated 16 I used to run.

Not sure what HP you have, or will have with new sticks, but a HTT 62/12 might be the ticket.

 

[glhs]

PDR should be able to answer the spoolup question. Once that is known, decide from there. I would be rid of that 18. 5 housing in a second. My truck with DDP3s would run cooler towing with a PDR HX-35/14 than with a 16. You just don't get enough air with a 18. 5. At least spend money on a 16 housing. I see them for sale used for $100.

Kurt

 

[dpuckett]

I actually had no problems or dislikes with the PDR HX35-18 I ran on my 91. I was more concerned about rotating inertial mass to get the huge (66mm) wheels turning. Like I said, I didnt like the stock HX35-14 towing- got too hot with my injectors (stock or marine), and I didnt notice much difference in spool. The 12 & 14s are out for me- I lean toward Greenleaf's theory of operation- less backpressure is good for the engine, though a 21 may be a little much. I am not hard enough on my stuff to break a HX40 shaft, I dont think.



Thanks for the thoughts and replies- keep em coming.



DP

 

[bmoeller]

The 12 & 14s are out for me- I lean toward Greenleaf's theory of operation- less backpressure is good for the engine, though a 21 may be a little much.

The HTT turbos (like mine) has dual wastegates, so that negates a lot of the drive pressure of a smaller housing. My mileage came up slightly after the new turbo. Less smoke too, unless I plant the skinny pedal with low/no boost. :-laf

I am not hard enough on my stuff to break a HX40 shaft, I dont think.

I beat the crap out of mine, and to my knowledge, the guy that bought it, is still running it. Although I did hear he needs more air now. Keeps adding fuel to fire. :-laf:-laf

 

[cerberusiam]

I lean toward Greenleaf's theory of operation- less backpressure is good for the engine DP

... . but how much is too much and where is the efficiency cut off? Drive pressure is a fact of life with a turbo charged engine, and, as emissions get tighter it becomes a bigger factor.



Drive pressures at less than 1 to 1 used to be the norm. Unfortunately, that causes other problems, not only with with emissions but also spool up and the power band. Unless one is totally oblivious, the desire to keep smoke at a minimum with the maximum of power is what we are looking for. that is simply not going to happen with these larger housings. The truck is either belching smoke unde rhard acceleration till the turbo lights, or it is simply not accelerating as it should be able to.



All that aside, there is a huge difference in 12 or 14 cm housing on and HX35 adn the same configuration on II and HTT's offerings. Quite a bit of design work has gone into building a turbo that will spool quickly, preovide the needed air across a broad range of boost, and keep the extra heat created by the higher drive pressures from having as large an impact. IMO, your fueling rate in relationship to the amount/quality of air has larger impact on EGT's than back pressure or drive pressure ever will until you get over the 600 HP range. The only way to address that is with a larger compressor and smaller hot side. Simple physics of the equation.



The contention less back pressure is better is correct on its face, but, what IS the actual number that you start seeing a reduction in efficiency? All things being equal, I would question the ability to tell the difference between a . 8 to 1 and 1 to 2 boost/drive ratio. With a free flowing exhaust and intake, a correctly sized WG, and the better volume of air you will get with a smaller housing/large compressor its very possible you might GAIN efficiency.



There has been huge amounts of R&D work done on turbos over the last couple of years that has pretty much negated the old school thoughts of drive pressure and the impact on efficiency. Its not going to be cheap but I think you would be quite happy with a 12cm/62 mm combo from several vendors. Unless your racing, the benefits will far out weight the negatives on a lot of different points.

 

[dpuckett]

Thanks for the input guys (and gals, if applicable, though I dont believe so).



I am leaning heavily toward the HX35, as it is a known quantity, and will fit my CURRENT setup perfectly. It may be a year or two before I get injectors, and I may sell the truck in that time. ALso, I have been on the beta testing of stuff before and sometimes it works, sometimes it doesnt work so well (DonM's nonIC EDMs come to mind :-laf). I'd rather have something I KNOW will work well, as I dont have a lot of money to spend on R&D. Not that I ever do... ...



DP

 

[Forrest Nearing]

sps62 and some bigol' injectors



do it

 

[dpuckett]

I may, eventually. Or I may do that to the 4x4 I plan to get when I start shoeing horses. Some 6x12s and a S300.



DP

 

[JAyers]

I run a sps62 and DDP 3's, she lights pretty quick. She starts singing at around 15-1600rpm and is gone from there. 49psi with the 3's and 60psi with the 6x18's well thats as far as my boost guage goes.

 

[dpuckett]

Ok, the 66-16 is out (for now), but I have come across the Dodgezilla, which is a HX40 wheel on the HX35 center for $10 more. Now, I would assume this is a stock 60mm wheel/ housing on the front of the HX35 cartridge. And, since stock likely (though not definitely) would have a slightly larger gap between the blades and housing, would it actually flow more air than the 58mm HX35? Or would the extra 2mm more than make up the difference?



I'll give City Diesel a call and talk to them about it.



DP

 

[JLEONARD]

Got to love the Dodgezilla just for the name.

 

[Forrest Nearing]

I've got a dodgezilla on my truck that will be coming off soon if you're interested.

 

[bgilbert]

How much does one of them HTT upgrade compressor wheel and housings run? There is one for sale in DTR classifieds. I think HTT will exchange chargers. This is what GL did. . only he sent a PDR 35 instead of a worn out stocker LOL.

 

[Greenleaf]

Remember that the term "slow spool-up" or "Lag Pig" is subjective. To one it is not slow, and to another it is. Take the "lag" opinions out of the equation.

 

[dpuckett]

Yes, that is true, Scott. But, I'd rather stick with what is familiar at this time, though I am still undecided. I like the sound of the 4" outlet, and the 16cm housing which I am pretty sure will be the happy medium (for my needs) between spool and flow. But there is the issue/ possibility of surge with the bigger impellar, which will negate any gains in the top end flow dept. I do most of my driving between 1200-2200RPM anymore.



DP

 

[Moab4x4]

I have the HTT stage II (58mm) upgrade and turbo rebuild. 16cm ported snail to manifold.

With POD's its easy to have too much fuel and I too am ~ 32 PSI and Red Pyro. I have lots of room on the fuel screw yet.

Driveabiliy is nice, spool is not instant but not bad. At just under 2K the truck just takes off. 20+ mpg highway, less around town and I am still dialing for less smoke on mild takeoffs.



I think I would rather have the 60mm wheel with my setup. I underestimated the bomb bug. :-laf

 

[BradyWilliams]

You could do a HX35 or a HX35/40 Hybred. (known quantity) But you could get a better spooling turbo and a better running truck by going with a PS62/80. Thanks

 

[dpuckett]

Ok, I'll bite. From a performance standpoint, what is to be gained by the PS62/80 (and what does the 80 mean?) over the HX35/40 hybrid? Will the EGT drop and/or MPG increase be worth the cost difference? (I know, that is subjective).



And, how much lag would the mass of the 66mm wheel add to the equation? (also, keep in mind that timing and fuelling can play just as big a part as the turbo in the lag department). Anyone have any side by side comparisons? Or anything even close? I dont mind waiting for the turbo to spool, but dont want to have to wait a week for it.



DP