Intake vs. Exhaust for EGT reduction

[Boondocker]

I know the answer is probably BOTH. But considering my high-end tastes, I'll probably have to get one at a time.



The question is, which will provide the most EGT reduction, particulary towing a 10K 5th wheel? My favored choices are:



AFE Stage II - Pro Guard 7

or

4" exhaust, maybe w/ the Aero Turbine.



I'm planning to hold out until TDR May Madness in Las Vegas. Hopefully some aspiring vendor will offer me a package deal too good to pass up



Considerations to weigh in the decision:

Having played horns in the band most of my childhood, I have a special appreciation for the tonal quality of bigger pipes! No offense to you stack runners, but 5" tube is just silly for my application.



Thanks for your thoughts.

Neil

Pros -

A little quicker turbo spool up to reduce smoke on normal driving. Quicker Turbo cool down. Any performance gain ~ better throttle response, HP or MPG improvements.



Cons -

I really don't want any more noise on either side of the turbo, especially since my wife sits on that side of the truck on road trips. I like turbo whine but she doesn't. Wouldn't mind dressing down 2-liter ricers with fart-can exhausts.

 

[Hohn]

If you want EGT reduction, intake first, then exhaust. The stock system will support 375 hp. I dynoed 390hp with stock intake AND stock exhaust, and EGTs were just edging into the high 1300s.



The AFE is a really good filter, but for max EGT reduction, you should go with a Scotty air system from Wildcat Diesel. The upside to the Scotty is that it gives more EGT reduction that any other intake (that I am aware of) and only costs around $200. The downside is that in order to see the big EGT reductions, you have to cut a cowl hole, and that turbo whine can get really bad.



If you don't NEED that kind of EGT reduction, then sitck with a regular AFE pro-guard. The stage 1, not the stage 2. The reason I say this is cost. An intake that's over $350 is a really tough sell to me. The stg 1 is only $200ish.



And with your fueling, you don't need that much air to keep it cool.



For exhaust, stick with the 4". Pay extra attention to the area where the downpipe transitions from the turbine outlet to the full 4" diameter. This transition should be as gradual as possible. This is where the BANKS exhaust really shines. I am no BANKS fan, but their exhaust is probably the best engineered on the market.



Good luck fueling around with your truck... .



Justin

 

[Boondocker]

Thanks for the reply Justin, hope you get you code problems sorted out.



Scotty II was my first choice, but my Jacobs exhaust brake solenoid controls are in the exact spot where the Scotty meets the cowl. I don't want to hassle with relocation. My present power upgrade is mild, but you know how it goes. I'm in infrastructure building mode now, just in case



Cheers,

Neil

 

[jrandol]

Hohn hit the nail on the head. If you have EGT problems go for the exhaust, it'll do a lot more than the filter. If your wife doesnt like the turbo whine then rule out the Scotty 2 then.

 

[Hohn]

I can see where you are coming from. I would only go with the AFE stg 2 if you know you are NEVER going to go twins.



At your level, a regular AFE pg-7 should give you all the air ou need. Be advised that the Mega-cannon setups also give lots of turbo scream (not like a scotty, though).



If turbine whine is a huge consideration, then that alone would have to be worth the additional $160ish to go from the stg 1 to the stg 2. For me, that's not worth it. But my wife doesn't often ride in my truck, so ymmv.



The real reason the Scottys are so effective (even if they flow less CFM) is the cowl feed. if you can't use the cowl, then the Scottys are mostly just another intake.



An AFE mega-cannon with the PG-7 should flow plenty and not be that loud. The Stg 2 (aside from price) seems to take up a LOT of space on that side. I REALLY like the new intake tube, though. i have decided that twins are not realistic for me-- and if I ever do have the $$ for them, I will not let intake/exhaust sunk costs discourage me, so it's a non issue.



The Codes are still in there (though the MIL is off now), and the EZ is on its way back to Edge. I am expecting a replacement soon.



Justin

 

[Hohn]

Originally posted by jrandol

Hohn hit the nail on the head. If you have EGT problems go for the exhaust, it'll do a lot more than the filter. If your wife doesnt like the turbo whine then rule out the Scotty 2 then.

Looks like Jeff says exhaust when I say intake. He has more experience than me in this area, so go with what he said. .



Justin

 

[jrandol]

Originally posted by Hohn

Looks like Jeff says exhaust when I say intake. He has more experience than me in this area, so go with what he said. .



Justin

Nope, I think you are right Justin, but if his wife doesnt like the Turbo Whistle than the filter isnt going to be a good fit. Exhaust is better there, my experience has been more decrease from the exhaust but I do have 5".



Boondocker, from your post it looks like you have RV275's. Is that right? Any other HP mods I missed?

 

[Joseph Donnelly]

1. 16 cm2 exhaust housing, but it is more sluggish to spool up the turbo. 14 cm2 may be a compromise, but only gives 75-100 deg. vs. 150-200 deg reduction with the 16. Or, bigger turbo.

2. Walker 21468 or no muffler, eliminate the resonator and stock muffler

3. pull out the collar from the air box to the fender.

Other things cost more, like 4" exhaust, camshaft, even bigger turbo. . .

 

[Joseph Donnelly]

1. 16 cm2 exhaust housing, but it is more sluggish to spool up the turbo. 14 cm2 may be a compromise, but only gives 75-100 deg. vs. 150-200 deg reduction with the 16. Or, bigger turbo.

2. Walker 21468 or no muffler, eliminate the resonator and stock muffler

3. pull out the collar from the air box to the fender.

Other things cost more, like 4" exhaust, camshaft, even bigger turbo. . .

 

[Boondocker]

no consensus

I was hoping for some consensus, but all opinions welcome.

Jeff, my engine mods are Edge EZ (set on #2), RV 275 injectors and TAG. Pulling a 5th wheel out of Las Vegas in the summer, which is about 6 months long here, is cause for heat paranoia even on a stock motor.



Joe, It looks like you're offering the low budget alternatives. The Walker 21468 seems to to be popular replacement, is that because it's a direct fit? I would not consider removing the resonator, drone is a bad thing. I don't think I understand your suggestion about removing the air box to fender collar. I suppose it's a bit restrictive in terms of volume, but it would seem that less cooler air is better than more warmer air. I'm not after more HP at this point, just less degrees. Some day, after the clutch, I'll go for those EDM injectors Hohn covets so much



My gut feeling is that I'm partial to the big exhaust sound. Having replaced exhausts before, I wouldn't really look forward to that job, especially compared to ease of intake swaps.



Are there going to be any BOMB parties at May Madness???

I am planning to finally buy a dyno session, you know how important those numbers are

 

[Green Machine]

My truck is a little older but I got a 4inch down pipe to a 5inch donaldson Kenworth muffler and 5inch out and over the rear axle and you can tell its runnen but its nice and mellow. Lowered my egts by 200 from stock. Got it from Rip Rook in Portland Or.

 

[Boondocker]

5" maybe

Thanks for the input Green Machine, and let me be the first to welcome you aboard. Maybe I'll have to be a little more open-minded about 5" exhaust. Rip has a great reputation, so maybe I'll query some vendors and get a few really biased opinions!