The HRC kit uses the stock pipe (as far as I know). I looked at there site and it says diameter of 2.25". So here's my question since my car is auto am I right to assume that with auto I need the turbo to spool as fast as possible. So is there any plans to come out with a 3" or 2.5" down pipe for the kits. Wouldn't a 3" turbo back exaust be my best bet for a quicker spool up?
#1103, "RE: HRC down pipe question" In response to Reply # 0
The theory as Corky Bell states it, is the less the exhaust, the better the turbo goes.
As far as expanding the downpipe, it really isn't a problem to get any muffler shop to make on at whatever diameter piping you like. As far as going as large as 3", I think that's a little excessive for most. It just depends though, I'm sure, from exhaust to exhaust. I currently just have a 2.5" cat-back and the turbo spools much quicker, however I haven't noticed any loss in low end torque. I did have a larger mouthed muffler tailpipe on before and had lost a lot of torque, with the same amount of turbo help, so there comes point when the exhaust can be just too big. I think with a higher compression car such as ours, where vacuum still supplies a lot of our muscle, a happy medium should probably be strived for.
If you start boosting more than 10-15 psi, the story may obviously change.
Jason 98' Eagle Talon ESi-T Mitsu Super 16g Turbo(HRC)
#1104, "RE: HRC down pipe question" In response to Reply # 1
I agree with Jason here; unless you're running a huge amount of boost--say 15-22 lbs. of boost, or a 20G--what you got should be sufficient. The theory is, a smaller pipe, i.e. a 2.25" DP best fits most applications because exhaust gas will travel at a greater velocity; as a result, you'll have a faster spool-up and lower end torque. I've discussed this topic with HRC and a bunch of other turbo guys and they all seem to agree with this theory. My .02 cents.
~Fly1
___________ Kon C
"Sometimes, a man has to do what a man has to do."
#1105, "RE: HRC down pipe question" In response to Reply # 2
We have run as quick as low twelves thru our turbokit downpipe section. This section replaces the forward portion of the stock downpipe, and enables use of the remainder of the stock downpipe and flex joint. Retaining the flex is a good idea to reduce strain on exhaust and turbo caused by drivetrain movement on rubber mounts.
As the market using our systems continues to step up, we are developing a 3" Eliminator downpipe to use with our kit. It will be offered as an option on new orders, and as a retrofit to existing systems alredy in use. It is 3" mandrel-bent 304 stainless steel wuth a large 3" flex joint. It will end at the stock cat inlet flange, but it will use our 3-bolt flange design to mate with our off-road and 3" hi-flow cats. We will offer complete 3" stainless exhaust systems to finish the setup as well. Other 3" exhausts can also be used with minimal mods.
Bill Hahn Jr. 98 RS Turbo: 10.87 @ 136 MPH HRC Stage V with N20 Nation's Fastest Street FWD 2G DSM www.turbosystem.com
Bill, will it fit onto other cats besides yours (I have a Randon technologies hi-flow cat now). when will it be available. I will buy one!!!! saves me a lot of trouble getting one custome made hehehehehe
#1110, "RE: HRC down pipe question" In response to Reply # 7
Hi Fly!
The prototype part is done, and looks tasty. The design uses a portion of the std. downpipe that came with your kit; about the first 5" of curved section.
For existing installations: You will cut off the std. turbo downpipe at that point and weld on a 3-bolt flange we provide. The new 3" downpipe starts there and then tapers out to a 3" diameter, goes under the engine where it meets a flex joint, then on to the cat con flange. I will post a photo of it to our website soon, as well as the availability date (expect about a month or so).
For new systems: We will provide this option, if chosen, as a complete bolt-in (no cutting of std. turbo downpipe required).
Bill Hahn Jr. 98 RS Turbo: 10.87 @ 136 MPH HRC Stage V with N20 Nation's Fastest Street FWD 2G DSM www.turbosystem.com
#1112, "RE: HRC down pipe question" In response to Reply # 8
Wow Bill,
Now I want one too maybe. (maybe I should've gotten a 3" cat-back...heh)
Anyhow, will this downpipe be alright to get if you have a 2.5" cat-back, and do you think it would effect torque at all?
I asked the first part b/c I notice a lot of the 4g6 owners get 2.5" DP's and then, if they choose, go with with either a 2.5" or a larger 3" catback. Is there a rule of thumb about piping diameter from turbo back?
Jason 98' Eagle Talon ESi-T Mitsu Super 16g Turbo(HRC)
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