Engine/Transmission (1998.5 - 2002) twins

[Scrappy]

I'm toying around w/ twins for my truck, but I have a few questions. The first is, are you using the first turbo to drive the second(sequentially), or are they running parallel to each other? Also, what are the pros and cons of each? I'm looking to improve my low end power without raising my EGTs sky high, IE little to no lag. If I use my stock HX35 W/a H2E sequentially will I get what I am after? I think that By going this way, the exhaust flow will have less of an effect on the intake air temp. Also in the parallel setup, how does the engine produce enough airflow to spin 2 turbo's at low rpm's

 

[tleclair]

Do a search on twins installed. Gizmo 007 posted that back on 11-02-2002. There is some really good info from him on this and also some pictures if I remember. Good luck.

 

[Scrappy]

OK, I'm starting to grasp the twin principle. I can use my stock turbo and a HT3B. Do I need to change my stock housing to a larger one(say 14-16cm3) or keep mine? Also what do I do with my wastegate? lock it closed or leave it functional and set it to open at what psi? Does it help to spool the big one by leaving the wastegate functional? will the drive psi get too high with it locked

 

[Proram]

Look for stuff from Jim Fulmer too. has a realy neat Setup.

Gizmo's is great too! All kinda info out there.



Proram

 

[Jim Fulmer]

I can use my stock turbo and a HT3B Yes



Do I need to change my stock housing to a larger one(say 14-16cm3) or keep mine Depends on what you want, how you want it to act



Also what do I do with my wastegate? lock it closed or leave it functional and set it to open at what psi? Most of us use external wastegates and just drive test(set) them.



will the drive psi get too high with it locked Mine is at 1 to 1



https://www.turbodieselregister.com/user_gallery/displayalbum.php?&userid=9347&albumid=420



Jim

 

[Scrappy]

more low rpm boost with lower EGT's @ 500 HP & max+ Gvwr

 

[Jim Fulmer]

Some use a hy-9 with a HT3B or BHT3B for quick spooling on the street, I had the 35/16 already so I used that, Piers wanted me to use a 35/18 and I probably will but I want one of his 35's to go with it. Once he works my pump I'll need the 18 housing I'm sure, also I run a PDR HT3B vise one off the shelf, it spools really good and I know it's got the TLC done to it. Seemed crazy not to spend the extra money considering what I was spending.



Jim

 

[Scrappy]

where did you find the external wastegate. Also thank you for indulging my dreams for the future.

 

[Scrappy]

Can I run my twins at my current fueling level or shound I hold off for the injectors and drag comp. Are DD3'senough for the twins?

 

[Jim Fulmer]

http://64.225.76.178/main.htm Billet wastegate!



You really don't need them, heck a single would do fine with a comp and DD3's from what I hear. But if you wanted to do it all at once that would be fine, as far as just running injectors with twins someone is going to say why!

 

[Scrappy]

I want to get a setup that will never have Egt problems and lower rpm lag. BTW thank you for answering my questions



James

 

[Chipstien]

Seems everyone tells me that twins will have more lag than a HX-40.

 

[RADdodge]

On the thread “Swapping <6 injectors to pass emissions,” Kevin had a surprising revelation. He has a Comp and DD2’s with I believe an HX35 (I have the same set-up) and he posted the following for Dyno numbers.



Comp on Level 3 produced 318hp and 864ftlbs

Level 4 was 313hp and 893tflbs

Level 5 was 301hp and 828ftlbs



Then Kris (Gizmo 007) said he needed more air because he was severely over fueled. Makes sense to me. Wouldn’t the spool-up be as quick as the smallest turbo used with the combination of air being better than either one individually at full boost?



BTW Jim, nice pictures. I wish you had some descriptions on them so I knew what I was looking at though. Very impressive.

 

[Scrappy]

The way that I understand the principle behind twins is: the small turbo is for the low rpm boost . As the rpms increase. so does the airflow to spool up the big turbo and the small one is bypassed on the drive side by the wastegate and is freewheeling. By doing this the boost comes on low in the rpm band (small turbo) and the EGT's stay under control(big turbo). IE the best of both worlds.

 

[MCummings]

Being not familiar with twins,, I don't have much weight behind my words,, but I don't think a single turbo setup, say, HX-35 w/12cm Housing won't spool any faster when coupled with a bigger turbo, say a PDR HT3B.



So the "Little" turbo won't spool any faster then it does now, it should spool the same ? But when the big turbo comes on, it makes the little turbo start flowing some serious air.



The little turbo compresses only the air it "sees",, so, say you have it setup up for 30PSI, and the "big" turbo is set at 30 PSI,, once the "big" turbo is spooled up,, you won't see 60 PSI,, you should see more like 90PSI, but I could be wayy off base, so take this with a grain of salt until you can confirm it.





By The Way,, the Stock headgasket won't deal with over 50PSI very well. With High Boost pressures a Copper headgasket, and O-Ringing the head and block are near necessity, while you have the head off, you might as well port and polish the head, and sneak in a PDR cam.



Also,, Towing @ Max GVWR with 500RWHP,, you will have alot more heat in alot more area's than just EGT,, Be sure to moniter your differential temperatures, transmission temps, Oil Temps, and Water Temps. (Not to burst your bubble) Bomb On James.



Merrick N. Cummings Jr

 

[Jim Fulmer]

BTW Jim, nice pictures. I wish you had some descriptions on them so I knew what I was looking at though. Very impressive.



I'll work on the captions then post back on this thread for you!



Merrick that's about right with the boost, I figure without the wastegate I could make 80 PSI!



You will (or I did) gain just a little bit more lag with the Twins over the 35/16 by it's self but I have got most of it out now playing with the AFC and raising light throttle shifts.



Jim

 

[Jim Fulmer]

Try this one for the captions for the pics of my setup.



Jim

 

[TxDieselKid]

Originally posted by Jim Fulmer

Try this one for the captions for the pics of my setup.



Jim

Those captions are great Jim, thanks for putting them in there.



Andrew

 

[Cooker]

Jim,

Thanks for putting the captions to your pics.



I have a question, which I'm sure has been asked before so I apologize, but it the extra weight of the second turbo hanging off the manifold a concern?

 

[HVAC]

Jim, where did you get the idea to flip the ex manifold. Who's truck did you first see this on?



The EE systems I've seen had the flange cut and rewelded.