You do realize what an EGR system does, and why, right? They are currently used in every production gasoline engine. It's called and Exhaust Gas Recirculation system. It uses exhaust gases, directly out of the exh port, to COOL the intake charge and chamber. It reduces the oxides of nitrogen and helps keep the engine out of detonation and ping.
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I am enjoying this discussion and learning a lot. Thanks for all the good information, everybody!
Every now and then, I see something that I take issue with though, and while I'm just a dilettante at this combustion theory business, I can add my 2-cents worth (and, that's what it's worth, literally) to the discussion, from time-to-time.
Here's how EGR was explained to me: Adding already-burned gasses to the intake charge is JUST like putting a brick in a toilet reservior. It takes up space, yes, but since there are no combustable products in it, it can add nothing to the combustion process. So, what is its value?
It takes up space in the combustion chamber in a benign manner, thereby reducing the amount of combustible gasses available to burn, and raise the temperature... and in doing this, reduces cylinder pressure. This reduced cylinder pressure allows more ignition timing (spark-advance) berfore detonation sets in, and also cools off the combustion process (and in the act of doing so, reduces oxides of nitrogen.)
It certainly does nothing to reduce the temperature of the intake charge ("It uses exhaust gases, directly out of the exh port, to COOL the intake charge.") before it gets into the combustion chamber. It is, after all, fresh (HOT) exhaust gas...
BTW, the inclusion of direct injection has made it possible to do away with EGR on some currently-produced automobile engines.
Having said that, I must reiterate that this ol' Valiant that we are building is a last gasp, hobby, project of two old geezers who should be in a couple of rocking chairs somewhere, reminiscing about their 1950s drag racing exploits in ther Olds 88's, out behind the airport (we had a quarter-mile marked off) and trying, in the process) to elude John Law... not breaking new (personal) ground with a bunch of unfamiliar (turbo) technology.
WEe have a LOT to learn, and not much time to get it done, so your many comments and information on this BB are much apppreciated by both of us!
Please keep the comments and input coming in as every one gets read, evaluated and if pertinent, acted up on.
Lookin' at a new header design as we speak... I'm about convinced that the long-tube design, attractive as it is, will cost us...
I ran an NHRA (Brand-X) Stocker for years, and was the Stocker class tech guy at 3 different drag strips; I know the value of a tenth... BUT, we are not building an NHRA "class" car here; just a test-n-tune play-toy, so we're not knee-jerk about flowing the head and buildding a sheet-metal intake. This is not a Comp Eliminator car...
Too darn old to learn the vagaries of EFI; besides, everything I read, says you can make just as much horsepower with a blow-thru Holley as you can with EFI... the EFI is just easier to get tuned correctly.
Besides, we already have the blow-thru carb and manifold...:blob:
Took a rocker arm to the heat treatment place; 16 on a Rockwell C scale... $50,00 to anneal 12 of them. The, $75.00 to re-heat treat them back to their original hardness (not very, it turns out.)
Pretty reasonable, I thought...
Now, I need to round up 12 to get treated to the 1.6:1 song-and-dance I have planned for them.=P~
Anybody got 12 to sell?