Lost my sanity - cut off exhaust - any thoughts?

R

rxsyclone

New member
I recently encountered more stress than I could handle, so that is my excuse for cutting the exhaust at the turbo on my daily driver stock Syclone. It is unbearably loud, and I expected it to boost 25 psi and blow up, but only boosts 10-11 psi at a little more than half throttle.
Is it because the stock boost control is efficient enough to deal with an open exhaust?
Or will I see 20 psi (and blow up) at full throttle? What advice would you give if I plan on slowly building the perfect exhaust (with VERY little money) and attempting to regain my sanity?
Sorry.
 
TYTILIDIE

TYTILIDIE

METH HEAD
Re: Lost my sanity - cut off exhaust - any thoughts?

My first question would be are you looking to blow your motor? It sonds like it. I would not have cut it at the turbo. You will now have to build a complete DP. Goo luck with that. I would take it to a local shop and let the pros handle it unless you are good with tubing benders and are a decent welder. I suppose you could try to get your hands on an aftermarket DP and exhaust though.
 
R

rxsyclone

New member
Re: Lost my sanity - cut off exhaust - any thoughts?

I was thinking that I'll build the perfect exhaust piece by piece, starting with the DP.
I'll leave the factory headers and turbo, and just go from there. So I need a really good downpipe. I have called around and most experts agreed that the Sy (being turbocharged) needs the least amount of backpressure possible. They literally told me that the best thing would be to cut off the exhaust if I could get away with it (without knowing that I actually did it). Of course there is a tradeoff, and I feel that I lost some major low rpm torque.
Could someone please explain to me how this works? Turbos don't need backpressure, but they spool up quicker if they have it??? and big torque engines need backpressure, but not if they're turbocharged??? I was also told that my turbo engine does not need to build exhaust velocity by travelling through the length of the exhaust (making a side exit system possible without compromising performance). I always thought that by cutting off at the downpipe, the exhaust just exits and goes in all directions, not creating a scavenging effect by building velocity.
I got this info from the vendors on this forum, as well as highly respected local turbo tuners.
I don't want to blow my engine, I always take extremely good care of it, I just didn't like the stock exhaust. I started like this on my RX-7, and now it has a T78 and hauls major ass reliably. I just feel that turbo cars should have exhaust mods.
BTW I floored it today and only saw like 12 psi... ?
 
Daron

Daron

Active member
Re: Lost my sanity - cut off exhaust - any thoughts?

Stock Syty wastegate is small. Add that to an open exhaust and the result will generally be overboost. If you must have a hacked downpipe, address the wastegate prob. An external wastegate on the crossover worked well for me.
 
R

rxsyclone

New member
Re: Lost my sanity - cut off exhaust - any thoughts?

Thank you Daron. Will do.
Still wondering about the backpressure issue, I plan on putting a muffler back on to quiet it down, maybe I'll regain some of the low rpm torque. I also don't understand why the truck doesn't overboost (although I haven't gone wide open in 3rd yet).
 
George Blake

George Blake

DONATING MEMBER
Re: Lost my sanity - cut off exhaust - any thoughts?

Try not to drive it like that...Carbon monoxide, you know that stuff that kills you, is now being pumped out in front of the cabin and you are now breathing it while you drive.
 
R

rxsyclone

New member
Re: Lost my sanity - cut off exhaust - any thoughts?

Update: have been daily driving all these months with NO exhaust, have not blown motor or overboosted, never exceeded 15.5 psi, truck is loud and slow, mileage seems to have improved, sometimes it feels really fast but low rpm torque is gone for sure. Besides the comments about what an idiot I am, explanations about how backpressure works in this truck would be VERY WELCOME, also, what kind of exhaust should I build? Thanks.
 
R

rxsyclone

New member
Re: Lost my sanity - cut off exhaust - any thoughts?

Update:
A while ago I reinstalled a normal exhaust system with a Flowmaster. The truck is much quiter now, way more enjoyable and faster. I estimate it at 300 hp and 380 tq and low 13s. Back to normal.
 
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