Hello,

Many posts have discussed removing EGR valves etc. and most have said it isn't really worth the hassel (PITA). Assuming for a minute you are building a brand new motor (1992 L98 MAP) that will not have to ever pass emissions, what effect/benefit/detriment will not plumbing/installing an EGR system and charcoal canister have on the motor?

I believe the PROM will have to be programmed with no EGR but I'm starting with a new computer tuned for what I'm putting in the motor anyway.

Any ideas are greatly appreciated.

Thanks...

 

You will need an EGR blockoff plate I believe. Running without EGR creates higher combustion temps which can create problems. I have heard you can run a lower temp thermostat to help as well. I have also heard something about the need for running stainless valves, but I'm not sure how true that is. I have interest in this as well as I plan to go with Vortec heads and no EGR as well.

 

Just keep the EGR functional if its not irreversibly damaged... Its not robbing you of any power, as its only functional at very light throttle and low loads like cruising on the highway. It helps keep combustion temps down but also helps fuel economy too, because it allows the engine to run more timing and less fuel without hurting itself... you'd have a noticeable drop in fuel economy if you disabled it completely, especially with a stock engine. Even if it was tuned out in the ECM as well.

 

Thanks for the input everyone. I knew about the blockoff plate(s). Forgot to mention the motor came out of a Corvette so it has the aluminum (113) heads which run much cooler than cast iron. Also, it won't be stock...Mild Lunati cam, ported, roller rockers, Tri-Y headers, etc. No catalytic converter either or maybe I should say, empty cats.

 

The Corvette engines still used EGR, it was just plumbed externally instead of through the cylinder head, like with the cast iron heads. Aluminum heads don't run cooler, they just disperse heat more quickly than iron... but thats a discussion for another thread.

Anyway, if you're upgrading the cam, then all the computer tuning for the EGR will probably be out to lunch and you will be better off to just disable it completely. Alot of the time, aftermarket cams have enough overlap ground into them to have a similar effect to what EGR does anyway, so you often get the same result anyway. This is the reason the LT4 and '01+ LS1 and LS6 engines didn't even have an EGR system at all from the factory. The cam grind was sufficient to have the same effect, so they just did away with it completely.

 

That is interesting to note about the cam and overlap. I already have a pair of 062 vortec heads and a GMPP vortec manifold to match which has no EGR which is why I plan to remove mine. I was going to go with the EBL and another camshaft like the Ramjet or similar. Would you think that would have enough overlap to have the same effect since its on a tight LSA? I also didn't really want to drill a hole in my header and try to plumb EGR externally plus find another expensive vortec manifold with EGR.

 

Got a part number for the cam you had in mind?

 

14097395 - Ramjet 350

196in / 206ex @50
.431 / .451 lift
109 LSA

 

Tight LSA on that one, but its a TINY cam, even for a 305... why do you want to use that one? I think ALL the TPI cams except the peanut-cam were bigger than that one.

 

I figured you would say its pretty small. I like the idea of excellent flowing heads and mild cam for the street. I have an LT1 cam on the shelf but the journals don't look too good and its kinda thrashed. I may be able to clean it up, but was thinking about something new instead. Honestly I'd like something like an XR264HR but that would require more budget for the cam and parts to accept that kind of lift on these heads. I've heard nothing but good things about the ramjet cam and I like the idea of maximizing the torque on the low end from 1000 - 5000rpms. I like that torquey feeling from 0 - 60. DD2000 actually shows better power than the LT1 with the same setup probably due to the tight LSA. The crane 2031 was also a consideration if I found one used. I was planning to mill the 062's .030 or so to keep the compression up and changing the springs. Looking to get ~300HP peak and around 350ftlbs or more from 2000 - 5000 for the street. I plan to build a 350 down the road with more aggressive parts so no need to go crazy.

Some of the TPI cams had a bit more duration on the intake except for 1 or more years which were like 207/213 or something on a wide LSA and they also have less lift.

 

Back to Air_Adam...and thanks for all the responses, my plan is to probably use a single plane cam. I assume that is what you are refering to we you mentioned "overlap". Reasoning being with some porting, Tri-Y headers and low restrictive exhaust the feeling is I don't need that extra push of incoming intake gases to assist with chamber clearing/cleaning. Couple this with no EGR, and knowing that I will be able to program the PROM as the motor is built, what then is the opinion of experiencing higher combustion temps. and decreased mileage?

Thank you...

 

Do you mean a 'single pattern' cam? All that means is that both the intake and exhaust lobes are the same. A 'dual pattern' cam will have one size for the intake, and a different size for the exhaust.

Overlap only refers to the amount of time, in crankshaft degrees, that both the intake and exhaust valves are open. Lots of overlap means theres a long period where both are open, and this is typically what creates the rough idle characteristics of really big cams. Its also what mimics the effects of an EGR system.

That tiny cam posted above won't have enough overlap to create either a rough idle, or enough reversion to act like an EGR system.

 

Sorry, my mistake...Yes I meant a 'single pattern cam'. Question remains the same or did you answer that by referencing the LT4 & '01+ LS1 and LS6 engines. If I pick my cam right, not running EGR should not present any significant problems.

Appreciate your help!!