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Questioning my exhaust setup

 
Old 09-24-2016, 05:04 AM
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Default Questioning my exhaust setup

I recently put a k24a2 in my 03 base. The setup is having a small isssue with knocking and egt that are around 100f higher than they should be. I think it may be an issue of backpressure. Currently i have a dc shorty with a catless 2.5" downpipe and a stock rsx catback. I need the custom downpipe so i can toss a cat in there for inspection. I am by no means out to make lots of power its an internally stock engine. I just want it to run well and last for years its my daily driver. Do you guys think the header or the catback is a bigger restriction???
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Old 09-26-2016, 07:24 AM
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Default Re: Questioning my exhaust setup

The shorty header and catless downpipe, although maybe not the highest flowing of setups, should not be an excessive restriction. If you want to test this theory just unbolt your stock catback and take a drive to see if your egt's drop. The following thread is a little old but the second poster answers the egt, knock and timing thing pretty thoroughly.

Relationship between knock, AFR, timing, and EGT? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

What ecu are you running? Kpro with tune? The tune could be the issue here seeing excessive knock.
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Old 09-26-2016, 04:45 PM
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Default Re: Questioning my exhaust setup

i honestly dont think id be able to make it out to a road to get up to cruising speed and back without getting pulled over. still may try it though!

using kpro. the stock tsx kal. i have adjusted the timing in those areas anywhere from 35-50 degrees. egt is all up there regardless. also adjusted afr from 14-15.2:1 in those areas. nothing really seems to give substantially better results...

im likely to get it tuned professionally i dont feel like speeding doing wot pulls. just want to make sure i dont have a problem with the setup before i pay for dyno time
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Old 09-28-2016, 05:39 PM
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Default Re: Questioning my exhaust setup

dropped the catback and hit the highway for a 5 minute cruise at 65mph. egt still up 1400f probably still climbing slightly i let out of it. good news i dont have to buy a new exhaust lol.....
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Old 09-28-2016, 08:43 PM
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Default Re: Questioning my exhaust setup

https://honda-tech.com/forums/forced...s-here-248965/

From this above post >>> "The BEST way to tune an engine is on the dyno- PERIOD. What EGT is good for is a reference for where the engine made maximum torque at wide open throttle. Once removed from the dyno, a similar air/fuel ratio can be established a later date by dialing in the mixture to achieve the target EGT. It is really the AFR that is important, not the EGT. Most engines will make maximum power at an AFR of between 11.8 and 13 to 1 however, the EGT may vary from 1250F to 1800F and is dependent on many factors."

https://turbobygarrett.com/turbobyga...g_rich_vs_lean
From this post:


For Example:
15.0:1 = Lean
14.7:1 = Stoichiometric
13.0:1 = Rich

Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality
When I first saw that you are running 14 to 15:1 I thought it seemed like you were running a bit lean, you might be making more power but at the same time you are running the risk of engine failure. If you want to be safe you might need to add a bit more fuel and keep the motor cooler. I'm by no means a tuner though and if you call around to some local shops that tune kpro some of the guys might be more than willing to help you out with your tune. In fact because you already have the motor somewhat tuned they may discount dyno time to finish up your tune for you, but many tuners don't want the liability of trying to fix someone else's broken tune. It's worth a shot though.
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Old 09-29-2016, 04:17 AM
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Default Re: Questioning my exhaust setup

Just for the record this is not full throttle at all just highway cruising at like 10-20% throttle. Under high load the afr is 12.6-12.8. The tune is the stock k24a2 calibration that comes with kpro. I just smoothed out the fuel maps and pulled some timing under high load to keep the knock count down.

My concern is increased wear and possible issues down the road from high piston expansion due to heat and stock piston to wall tolerances should the high temps persist. I am planning on a professional tune but i want to make sure i have no issues with my setup that would make the dyno time ineffective



Originally Posted by bonusgoat View Post
https://honda-tech.com/forums/forced...s-here-248965/

From this above post >>> "The BEST way to tune an engine is on the dyno- PERIOD. What EGT is good for is a reference for where the engine made maximum torque at wide open throttle. Once removed from the dyno, a similar air/fuel ratio can be established a later date by dialing in the mixture to achieve the target EGT. It is really the AFR that is important, not the EGT. Most engines will make maximum power at an AFR of between 11.8 and 13 to 1 however, the EGT may vary from 1250F to 1800F and is dependent on many factors."

https://turbobygarrett.com/turbobyga...g_rich_vs_lean
From this post:


For Example:
15.0:1 = Lean
14.7:1 = Stoichiometric
13.0:1 = Rich

Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality
When I first saw that you are running 14 to 15:1 I thought it seemed like you were running a bit lean, you might be making more power but at the same time you are running the risk of engine failure. If you want to be safe you might need to add a bit more fuel and keep the motor cooler. I'm by no means a tuner though and if you call around to some local shops that tune kpro some of the guys might be more than willing to help you out with your tune. In fact because you already have the motor somewhat tuned they may discount dyno time to finish up your tune for you, but many tuners don't want the liability of trying to fix someone else's broken tune. It's worth a shot though.
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Old 09-29-2016, 07:13 AM
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Default Re: Questioning my exhaust setup

Yeah I wasn't thinking about WOT and cruising loads. Are you running OEM plugs? What about gas, what kind are you running? 92 octane? The motor is stock compression?
I'm thinking it might help to post your concerns here >> https://www.hondata.com/forum/ << since these guys all have experience either running kpro and/or tuning them. They might be able to answer your questions.
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Old 09-30-2016, 01:32 PM
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Default Re: Questioning my exhaust setup

i use 93 octane, either mobil or sunoco. i had some iridium ngk 7's but swapped them out for some bkr7e's with sanded ground straps so i can monitor the timing. the egt is worst on the 20 degree cam angle, so im probably going to lock it back to 10 and just putt around town till i get on the dyno hopefully in october.
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