Daily Driver Twins??

[mgoncalves]

I've been doing some thinking (smell the smoke?), and have a couple of questions about twins in the real world.



First off, can you run an exhaust brake with them? I don't see why not, but then there's a lot of things I don't see.



Second, what happens when you bark twins? With a stick, I can see where it would be really easy to have to shift up and drop from 50psi to 0psi going up a pass loaded down.



Third, what is the noise level of twins in the cab? In the last few months I have been real touchy to engine noise in the cab, to the point of getting rid of the AFE. I imagine most of this depends on what kind of filter you have and where it is located.





Any comments or ideas are appreciated.



Matt

 

[Idaho CTD]

It sounds like you tow a lot. If that is the case and want twins I would stick with a smaller set (stock 35 to a 35/40 with a HT3B 23 or 26).



One of the benefits of twins is quietness. They are quieter if you get the compressor cover on the big turbo sealed tight.



Yes you can run an exhaust brake with them but it would have to be an inline 4" minimum and a 5" would be better.



My truck is a auto but the only time I've barked mine was on the dyno. The truck came out of lockup and I let off instantly. It was pretty cool to hear two turbos bark but I dont think in everyday driving it would easy to bark them unless you let off too fast.

 

[mgoncalves]

I don't tow much at all, but I do have a slide in and will probably pull a couple of four wheelers on occasion (I wish every weekend). Most of that will be at higher elevations, 8,000+. As it is now with my stock HX 35, I can't use the comp at all with a slight load going uphill, the injectors are borderline too hot and I'm planning on going a little bigger with those anyways.



I can bury the pyro when empty with the comp cranked up, however, I don't want to increase the turbo lag much more than what it is now. So, a bigger single doesn't really appeal to me. I would like to go with the HT3B to keep my 35 company, I don't know what exhaust housing would work best for me. I also wonder what would be the optimum exhaust housing for the 35.



If I can run an exhaust brake with them , that is awesome. I would certainly like to have one even when empty going down some of these hills.



One thing I don't quite get from your post is sealing the compressor cover on the big turbo. I don't understand what you mean .





Thanks for the help



Matt

 

[Idaho CTD]

PDR modifies the HT3B by installing a o-ring on the compressor side amoungst other things. That keeps air from seeping out causing a whistling sound. The B2 doesn't have that and is quite obnoxious compared to the PDR modified 3B's. The 40/3B combo I ran before this combo was way quiet inside the cab.



If I was at your altitude I would run a 35/40 hybrid with a 14cm2 housing on top and a 3B with a 23cm housing unless your looking for high hp then the 26cm would be better. Along with a set of Mach 3's to Mach 4's this would make a pretty healthy combo and be plenty streetable.

 

[BillGotthelf]

Well I'm running the B1/B2 combo and the turbo whistle is no diffferent than the whistle I used to get with my single PDRHX40. As far as the hx35/h3 combo it should work. I don't know how they would handle barking them. Power should be much more controllable (read egt's) with the twins.

 

[Idaho CTD]

Bill,



Once you have ridden in a truck with the PDR modified 3B on the bottom you kind of get spoiled. My 40/B2 combo wasn't much noisier then a single 40 but compared to my 40/3B it's obnoxious. I would bet the same thing can be done to a B2 compressor cover or due to the better clamping on the cover maybe just some silicon.



Nathan

 

[Vaughn MacKenzie]

I've been told even the best and most effective twins setup will always have more lag than a single turbo, at least the smaller singles. Is this true?



Vaughn

 

[mgoncalves]

That's the way I understand it also, which is why I don't want the smaller turbo to be much bigger than the stocker.



I've got another question for you guys. If I use the HT3B with my HX35, would I want to use a wastegated housing on the 35 or would an external wastegate be required to keep from overspooling the 35? That's figuring I go with EDM mach 4's or so. If it's needed, where do I find an external wastegate?



Also, what 's ballpark to have the HT3B done by Piers?







Thanks for the help

Matt

 

[Chipstien]

You can use the stock turbo for the top but will need to modify the wastegate so it can keep up with the amount of air that will be moving through there.

 

[BillGotthelf]

Vaughn with my setup the lag appears to be the same as my old PDRHX40. Biggest difference is when it spools up things get real blury real fast. Today I used power level 4 on my TST for the firest time (trying to break in turbos) and when it spolled up and shifted to 2nd the tires spun for 50 feet before they hooked up. If you drive it normally (whatever that is) it drives just like the old hx40 and ddIII's.

 

[Idaho CTD]

With equal fueling I lost 100-200rpms of spoolup when I went from a single PDR40 to a 40/3B combo. Basically it's like going back to a stock 40 from a modified one. The boost is slighly slower coming on in twins until the large turbo starts providing boost. In my example 0-20psi was kinda lazy but after 20psi hang on.



Matt,



You can have the existing 35 wastegate opened and it will work but with heavy fueling it probably wont be enough to wastegate properly. If you use an external WG it can be placed between the exhaust manifold and turbo or welded directly to the turbo housing. If you do a search on twins there are pictures of how others have done it. External wastegates can be found on ebay, from turbonetics, and just about any other turbo shop can get them for you. A PDR 3B use to cost about 550 but I haven't priced them recently. You can find stock ones for 350-400.



Nathan

 

[Vaughn MacKenzie]

Bill, that's the other thing about Twins. . . Spoolup time followed by a sudden transition to Warp 9



Vaughn

 

[Amianthus]

Yeah, mine act that way too. Anything below10 psi and 1700 RPM is pretty laggy. But once you break 10psi, it's a heartbeat to 65psi. If I stay around 2000 PRM, I can stab it and it reacts pretty well too. But below either of those limits and stab it, I'll just say that my cloud can be seen from space.



(BTW, I run a B-1 std. and a 3b)