Those with twins - straight piped?

[JStieger]

I love how my truck sounds now - really deep like a 1st gen, yet mellow baritone, turbo whistling sound - with the 4" straight through muffler and single turbo. In a few weeks I'll be installing twin turbos and will have to modify my exhaust to fit them. I am wondering from the folks that have "been there, done that" how much they will quiet the exhaust?



So far I have PM'd a couple 3rd gen members - one with stacks and one with 5" exhaust - and both don't mind the straight piped twin turbo sound.



Keep in mind I drive a lot with the radio off too just to hear the Cummins sing... but I don't want to get to like when I ran an open downpipe for a week (ears ringing)!



-Thanks-

 

[DrewStory]

i dont have a 3rd gen put i can say that it cuts engine noise in half. anymore i cant really hear my exhaust all i hear is the whine of the turbos.

 

[mattymac]

Yeah it will be alot quieter. I would SP it. What bottom charger are you going to be running? Im asuming your running the 62 up top?

 

[JStieger]

I guess straight pipe it is! I'm installing BD twins (with the Super B on top) thanks to another generous TDR member and then I'll sell the SPS 62. The Super B is also equivalent to the HTBG that High Tech Turbo sells.

 

[bmoeller]

I think the 2nd gen sound pretty good with twins. Oo. Oo.



http://www.thedieselgarage.com/forums/showthread.php?t=12483

 

[JStieger]

I think the 2nd gen sound pretty good with twins. Oo. Oo.



http://www.thedieselgarage.com/forums/showthread.php?t=12483

Oo. That's what my truck wants to sound like when it grows up!! That's ________ awesome!!!



Do you have a downloadable file for that that you can email me? Please, please, please! I can't download files off those media hosting websites.

 

[bmoeller]

No, I'm afraid I don't. Are you member over on the TDG (free site )? If not, I'll send a PM to crzycowboy, to see if he does.

 

[JStieger]

I'm not a member over there yet. I'm already on 4 sites... with not enough time in the day as it is.



That would be great if you could get the sound file - I'd really appreciate it!



It will be a good Windows opening sound or whatever. If you can't get it, no biggy either.



Thanks!

 

[jvjump]

My twins make more noise than exhaust note does. It has a four inch straight pipe . With the single it was some what loud well real loud ! With the twins it has a wonderful whistle. Sitting at idle i would say it is close to being as quit as a stock truck. No drone or any thing running down the road very happy with straight pipe on my twins. Let me know how they fit i had a few little thing that i feel could be a little better for the price you have to pay.

 

[JStieger]

Let me know how they fit i had a few little thing that i feel could be a little better for the price you have to pay.

Do you have the BD's also? I bought mine from AK Ram and he posted a while back about cleaning up some of the welds as well as doing some port matching. Did you find the same?

 

[Todd T]

Mine is a 2nd gen with twins and 5" straight out a tailpipe over the axle. the exhaust sound is way quieter than a straight piped single, almost too quiet for my likes.



I had a single stack on it and it sounded great (the absolute best) but i couldnt put up with the soot being sprayed all over everything i owned anymore.

 

[JStieger]

Update!

3rd gen + BD twins + 4" straight pipe = almost like a 12 valve straight pipe mellow deep sound.



I did run with an open downpipe and the twins for a week and that sounded like a 2nd gen 24-valve straight pipe (loud and very deep).



Either combination didn't have the typical 3rd gen bumble bee sound for lack of a better way of describing it.



I wish I had a video camera to record it for you guys!

 

[Luken]

How do they spool compared to your old single?

 

[JStieger]

How do they spool compared to your old single?

They "feel" like they spool like when my truck had an HTB2 62/12 turbo - fast with minimal smoke. With the Stage 1 CP3, they get going even faster! Spool is subjective though so I dynoed various turbos quite a bit except for the stock turbo as detailed here and here :



In all honesty if it wasn't for me being curious and trying the SPS 66 I would never have the SPS 62 and still have the HTB2 62/14 with the HTB2 62/14 having a slight spooling advantage, but drive pressure disadvantage, due to the hair smaller exhaust housing. All are excellent turbos with excellent service from their respective venders and ultimately it just depends on what you want to do with your truck.



I just got an awesome deal on these twins that I just couldn't pass them up! I'll be the first to admit that BD has negative connotations to many people for whatever reason, but they really did their homework on these twins. Just do a search on AK Ram's posts on them as well as see his drag racing videos. These videos plus the fact that his posts are very straight up on them were a huge deciding factor and really speak for themselves... so I compulsively bought 2/3 of the set from him when he decided to upgrade. . I was actually thinking about using the SPS 62 as a top turbo, but did not want to go through the fabrication exercise as well as being unhappy if the SPS 62 spooled slower in the twins configuration.



When I ran my top numbers with the SPS 62 at 540 HP/1000 TQ (90 HP injectors, TST 4x2, stock CP3) the EGT and boost were pegged and it was smokey.



With the BD twins, same injectors, same TST settings, modded CP3 I run out of rpm before max boost in all gears except 6th, which hits 52 psi at 100 mph at 1100 degrees. Oh yeah... the smoke is a small "poooof" like a stock truck does taking off from a light when one mats it.



Anyhow, I was going to dyno this week, but will postpone until I get my modded CP3 fixed up and re-installed. I will post the results for sure!



The top numbers are great and all, but what I really want is the area under the curve over a wide rpm range. That's what I hope the quick spooling twins and especially the modded CP3 do (as shown by Tomeygun's dynos with it).