Tallywhacker

iTrader: (6)

Hey fellas,first the quick and dirty:

My brother has an 02 1500HD w/6.0/4L80. He just bought an STS kit off ebay with a PT76GTS w/.81 a/r,front mount intercooler,a set of 42# injectors,wastegate,bov,walbro,etc.

The truck is lifted 6'' w/35" BFGs and is regeared w/ 4.56s.This truck does some occasional towing and quite a bit of offroad duty during hunting season.

I will be tuning it w/HPtuners and I'm guessing the 42s will end up being small.If that's the case we'll snag up a set of 60s and kick the 42s down to his 01 SS w/LS6.Call it recycling.We're not shooting for any specific power #,basically as much as it'll make safely and reliably.

I've worn out the search functionand we'll be sticking with the truck manifolds and we'll be wrapping the headpipes as far back as we can and I'm thinking about a turbo blanket as well.

My main question at this point is in regard to optimum hotside pipe size.My brother reports that the headpipes are~2.5" coming out of the flange then expand up to 3".Stock there was some sort of merge on the passenger side to a single but he had this removed and true duals installed.

I'm wondering if this might be a little large and we might be better served by fabbing new 2.5 mandrel headpipes back to a merge.Then the question arises as to what size we should run back to the turbo after the merge.I'm thinking at least 3" probably more like 3.5"?

My plan is to run a single 4" DP(w/straight thru muff)from the turbo to behind one rear tire and run the wastgate dump into another pipe to behind the other tire.Use the same tips on both sides so it'll be true duals under full boost.

Any input/tips/advice is greatly appreciated.

Wilde Racing

iTrader: (26)

Welcome... I would stick with the 2.5 pipe and merge them right before the flange. if you merge sooner stick with 3 max.. the pipe from STS is 2.5, well it was in my kit anyway...

WJ MARK

iTrader: (7)

Id personally run a single DP instead of Duals.

Tallywhacker

iTrader: (6)

Gotcha...that's kinda how I was leaning after reading Zombie's threads.Would be nice to just merge the existing pipes and let er rip but if it's not gonna run right...

At least it's a lifted full size truck,it's damn near like working on a lift.

Tallywhacker

iTrader: (6)

I haven't priced 4" pipe locally,but I'm thinking it might be more cost effective to order summit's 4" diesel exhaust and hack it up to work in my application.

It'll still be one DP,the other side will just be the wastegate dump.I'll probably be able to reuse the existing 3" tailpipe just hafta buy another 4" tip to match the other side.There won't be anything coming outta the wastegate side til full boost when the wastegate opens.

FrostKing

Leave room in your plans for a 2nd wastegate.

Tallywhacker

iTrader: (6)

The wastegate is a Tial not sure what size.

Having a dedicated pipe for the wastegate will make it even easier to add extras if need be.

There's also the chance that the wastegate discharging into it's own pipe(or to atmosphere)and not having to deal with the exhaust pressure in the DP will allow the wastegate to flow more and negate the need for a second one...

Anybody with wastegate problems ever try that?

Tallywhacker

iTrader: (6)

Forgot to mention that we are also gonna run a ZO6 cam for a little extra.

Talked with Mort via PM and he says his stock pipes worked fine on his 1500HD so it looks like we'll be wrapping the stockers and seeing how it works.

Anyone else have any input?

slowec

iTrader: (9)

why???

ILuvJDM

iTrader: (4)

seriously, the average truck running anything under 1bar has no need for a 2nd wastegate... why would you waste time and money on that other than bling?