1990 5.7 TBI EGR delete pit falls

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Erik the Awful

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I started work on my 193s yesterday, using this video series for reference.
xc_hide_links_from_guests_guests_error_hide_media

I started with the head that had the worst valve seats, and I really think the head is garbage. It's a good thing, because I think I dorked it up. It's only my second time porting heads. When I was unshrouding the intake valve, like he shows, I bounced out of the pocket a couple times and put a dimple into the quench area. I recommend putting masking tape across the bottom of the combustion chamber so you don't do the same, but there's a good chance you have more experience than me.
 

Schurkey

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I started work on my 193s yesterday,

I think I dorked it up. It's only my second time porting heads. When I was unshrouding the intake valve, like he shows, I bounced out of the pocket a couple times and put a dimple into the quench area. I recommend putting masking tape across the bottom of the combustion chamber so you don't do the same.

Two things to note about porting:
1. Just about every home-porter uses a completely deficient tool. If the side of your porting tool says "Dremel", you're wasting time, money, effort, and enthusiasm. I used to port with a Mac Tools (Made by SP Air) 1/2-horsepower air die grinder that I put an extended "handle" on the back end for control, and I still do some work with it--but most work is done with a pawn-shop NAPA 1-horsepower large-body air die grinder. Yes, these take a REAL air compressor.

https://www.amazon.com/SP-Air-Corpo...ords=Die+grinder+SP+air&qid=1601398468&sr=8-2

I don't know who made my NAPA grinder. It's similar to this one.
https://www.amazon.com/AIRCAT-6270-...words=1+hp+die+grinder&qid=1601398653&sr=8-27

2. I cover the quench pad area, and anything else I don't want to nick with layers of duct tape--tougher than masking tape.
 

El Tigre

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Zero performance advantages to deleting EGR. There are plenty of drawbacks though. Poorer gas mileage, less throttle response, and sky high cylinder head temps. Just to name a few.
 

PlayingWithTBI

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Poorer gas mileage, less throttle response, and sky high cylinder head temps. Just to name a few.
Not quite true, I can get better mileage with HLC, your throttle response isn't affected when EGR drops out at ~50%+ TPS, same with sky high cylinder temps. My biggest problem with EGR is introducing already burned gasses back into the combustion chamber, you need oxygen to burn efficiently. HLC adds SA too but, it raises AFR so, you're burning less fuel and hence, better MPGs.

Here's EGR (on the left) and HiWay on the right. A lot more options on HLC vs MAP and AFR. We just richen up the AFR when at higher MAPs
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El Tigre

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EGR also includes unburned fuel as it adds pressure that aids cylinder fill. Their whole purpose is to help gasoline engine operate more efficiently... They've been used on practically everything for over 40-50 years. Probably untold millions of dollars of research support their effectiveness... If automakers could duplicate the advantages of EGR valves via PCM tunes I believe they would. EGR is only functioning at partial throttle to begin with. So it has zero effect on wide open throttle performance. Delete it, or don't... It's your money, time, and vehicle. There are no free lunches though.
 

kenh

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I started work on my 193s yesterday, using this video series for reference.
xc_hide_links_from_guests_guests_error_hide_media

I started with the head that had the worst valve seats, and I really think the head is garbage. It's a good thing, because I think I dorked it up. It's only my second time porting heads. When I was unshrouding the intake valve, like he shows, I bounced out of the pocket a couple times and put a dimple into the quench area. I recommend putting masking tape across the bottom of the combustion chamber so you don't do the same, but there's a good chance you have more experience than me.


I watched that series also. The guy is not doing much to the heads except just cleaning up what the MFG failed to do. Basically removing flash and some humps and bumps. Seems mostly like a common sense port job.

Ken
 

Pinger

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Not quite true, I can get better mileage with HLC, your throttle response isn't affected when EGR drops out at ~50%+ TPS, same with sky high cylinder temps. My biggest problem with EGR is introducing already burned gasses back into the combustion chamber, you need oxygen to burn efficiently. HLC adds SA too but, it raises AFR so, you're burning less fuel and hence, better MPGs.

Here's EGR (on the left) and HiWay on the right. A lot more options on HLC vs MAP and AFR. We just richen up the AFR when at higher MAPs
You must be registered for see images attach

What is HLC and SA?
 

Erik the Awful

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Just about every home-porter uses a completely deficient tool. If the side of your porting tool says "Dremel", you're wasting time, money, effort, and enthusiasm.
Yup. I had a dremel years ago. I burned it up porting a rotary engine. I replaced it with a Ferm electric grinder that's about three times the size of a dremel. Works great and has both a 1/8" and a 1/4" chuck. I just wish it had a longer, narrower nose. https://www.amazon.com/Ferm-Variable-Speed-Rotary-Cutting/dp/B00KYVL4B4

I watched that series also. The guy is not doing much to the heads except just cleaning up what the MFG failed to do. Basically removing flash and some humps and bumps. Seems mostly like a common sense port job.
I'm trying to duplicate how he opened up the combustion chamber around the intake valve. You really have to be careful to work the outline first, and not try to dig down into the chamber. It's really easy to dig too deep. I'm not going to rework the ramps, but I am smoothing the angles and humps right behind the valves.
 

Pinger

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Not quite true, I can get better mileage with HLC, your throttle response isn't affected when EGR drops out at ~50%+ TPS, same with sky high cylinder temps. My biggest problem with EGR is introducing already burned gasses back into the combustion chamber, you need oxygen to burn efficiently. HLC adds SA too but, it raises AFR so, you're burning less fuel and hence, better MPGs.

For highly turbocharged diesels EGR is essential for NOx control but on our lightly stressed sparkers I'm not a fan.
Out of interest, in the sub 50% TPS region where EGR is activated, what percentage of air flow is admitted?
 
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