Would anyone here pay for a 617 intercooler kit? - Page 7 - PeachParts Mercedes-Benz Forum

boneheaddoctor · #91 11-01-2004, 03:55 PM

Quote:

Originally Posted by Brian Carlton

That makes sense. However, this crush bend machine would create bends that would not constrict the pipe too badly. Slight constriction but not terrible, IIRC. The main requirement for the machine was to utilize very heavy wall tube. On thin tubing, it would just kink the tube immediately.

Cush bed pipes do contrict flow considerably. too the effect of reducing flow by about the equivalent of 1/2" reduction in diamerter. Not small thing. Heavy wall tube would be surprising to see on an exhaust but I don't see why it wouldn't work, except for the weight issues.

BoostnBenz · #92 11-01-2004, 03:59 PM

Quote:

The loss of torque experienced by an engine due to too large of an exhaust is restricted to non-turbo applications.

I don't agree. If the turbo can spool easier by having less backpressure on the other side of the turbo then of course it'll have less backpressure before the turbine. There are many people on the Cummins forums who take a 180hp motor and make it 500+hp, they notice the difference in low end torque with a 4" and 5" exhaust no matter what stage they are at in power.

Brian, I see no reason that you'd want thick walled tubing. The only bigger waste would be having stainless steel. While my downpipe's flex section crapped out a year ago my exhaust is 22 years old, is made from 16ga steel, and the slight exposure to salt over the years or just normal driving hasn't really effected it. Diesels don't really benefit from such systems as their exhaust isn't corrosive like G@$$ER exahusts are.

Most muffler shops that I know of bend their own systems, granted the hydraulic machine isn't mandrel bent and the guy getting paid minimum wage isn't concerned about making the optimal turns or keeping the system looking nice, yet getting it done so he can move on to another vehicle. Road Race Engineering did a flow test on mandrel bent versus press bent for DSM exhausts, they found that a 3" press bent system barely out flowed a 2.5" mandrel bend system. A welded mandrel system looks like hell but should flow well.

Brian Carlton · #93 11-01-2004, 04:02 PM

Quote:

Originally Posted by boneheaddoctor

Cush bed pipes do contrict flow considerably. too the effect of reducing flow by about the equivalent of 1/2" reduction in diamerter. Not small thing. Heavy wall tube would be surprising to see on an exhaust but I don't see why it wouldn't work, except for the weight issues.

I'm quite sure that it was not this severe. The tube becomes ovalized and the distance across the thinner dimension might drop to 65% of the original diameter. But, perpindicular to this dimension, the tube will have grown somewhat so that it probably is 20% more than the original diameter. The net result is probably a flow reduction of 20-25% maximum. I think that I could live with this if 3" pipe was utilized.

boneheaddoctor · #94 11-01-2004, 04:07 PM

Quote:

Originally Posted by BoostnBenz

I don't agree. If the turbo can spool easier by having less backpressure on the other side of the turbo then of course it'll have less backpressure before the turbine. There are many people on the Cummins forums who take a 180hp motor and make it 500+hp, they notice the difference in low end torque with a 4" and 5" exhaust no matter what stage they are at in power.

Brian, I see no reason that you'd want thick walled tubing. The only bigger waste would be having stainless steel. While my downpipe's flex section crapped out a year ago my exhaust is 22 years old, is made from 16ga steel, and the slight exposure to salt over the years or just normal driving hasn't really effected it. Diesels don't really benefit from such systems as their exhaust isn't corrosive like G@$$ER exahusts are.

Most muffler shops that I know of bend their own systems, granted the hydraulic machine isn't mandrel bent and the guy getting paid minimum wage isn't concerned about making the optimal turns or keeping the system looking nice, yet getting it done so he can move on to another vehicle. Road Race Engineering did a flow test on mandrel bent versus press bent for DSM exhausts, they found that a 3" press bent system barely out flowed a 2.5" mandrel bend system. A welded mandrel system looks like hell but should flow well.

How can you have less tourque and be under boost at lower rpm at the same time? That would make a N/A car stronger. Can't comment on the Cummins.....

And the crush to mandrel bent thing carries over to gassers too. Thats why I made that comment. 3" is the recomended diamert on 1.6 Honda turbo motors.....mostly because there is no room for anything bigger under such a small car.

BoostnBenz · #95 11-01-2004, 04:14 PM

You can't, probably bad wording on my part. How would it make a N/A car stronger? I forget the saying... you buy horsepower and you drive torque.

Yes, RRE is a performance products manufacturer for DSM (gas).

boneheaddoctor · #96 11-01-2004, 04:17 PM

Quote:

Originally Posted by BoostnBenz

You can't, probably bad wording on my part. How would it make a N/A car stronger? I forget the saying... you buy horsepower and you drive torque.

Yes, RRE is a performance products manufacturer for DSM (gas).

well if a big pipe helps it spool sooner ( make boost) at lower rpm how could torque suffer is what I meant. Not a DSM guy, know hondas best in the rice rocket catagory

Old300D · #97 11-01-2004, 05:10 PM

Quote:

Originally Posted by boneheaddoctor

well if a big pipe helps it spool sooner ( make boost) at lower rpm how could torque suffer is what I meant. Not a DSM guy, know hondas best in the rice rocket catagory

Quite correct, torque will not suffer. You increase the pressure differential on the turbine by reducing exhaust system backpressure, and it spools faster. That equates to more torque sooner. Maybe it's just the KKK turbo, but my Benz with no muffler spools very quickly.

By opening up the exhaust on a normally aspirated engine you will help top end flow for greater power, but torque at lower rpms will probably suffer. I don't know the reason for this, but I know it happens because I've experienced it. It totally sucks for driveability.

Brian Carlton · #98 11-01-2004, 05:23 PM

Quote:

Originally Posted by BoostnBenz

Brian, I see no reason that you'd want thick walled tubing. The only bigger waste would be having stainless steel. While my downpipe's flex section crapped out a year ago my exhaust is 22 years old, is made from 16ga steel, and the slight exposure to salt over the years or just normal driving hasn't really effected it. Diesels don't really benefit from such systems as their exhaust isn't corrosive like G@$$ER exahusts are.

Jeff, I guess thick wall is relative. The very thin wall tubing found in cheap mufflers and pipes from the chain stores cannot be bent in the bending machines. I don't think I need anything thicker than what you have there.
The reason to consider stainless is that it costs about $100. more than the aftermarket replacement exhaust for the vehicle. If I could get a decent shop to bend up 3" pipe, then, that is the way to go. I'm sure that I could get it done for half the cost. Problem is finding the shop to do it.