Did it make a noticeable difference? The thought of recirculating hot water back into the cylinder head seems counter productive to me, especially on a hot running third gen.

I will be installing my new Stewart stage 1 pump this weekend and would like to hear what you guys think of this. I'm using one of the stewart thermostats with holes so the bypass isn't needed and this may help reduce my temps a little.

Any input appreciated!

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91 RS/3.1 - Stock except stereo system, daily driver.

86 IROC - T-Tops, 350/TH350 w/shift kit, 2600 Stall, 3.42 geared 12 bolt, Performer 750cfm, Performer RPM, Comp Cams 280 magnum, Hooker 1 5/8" shorties, Flowmaster Y pipe, 3" to Flowmaster 2 chamber Dual outlet.

 

I've wondered about this myself.I know that in the latest GM Hi tech Performance Magazine, they're building a thirdgen Firebird with a Tuned Port Motor, and they're using that Evans Non-Aquious Propylene Glycol (NPG)instead of the usual water/glycol mixture.This stuff needs to be run 100%, no water, has a boiling point of 370 deg F.After reading about this install, they say Evans recommends a high volume water pump,bypass plugged,smaller water pump pulley(overdriven),no thermostat,and a 3-5 PSI radiator cap!I guess this stuff doesn't rely on pressurization,due to the super high boiling point,they just super-circulate it through the system.They say it'll make the operating temp a little higher, but it cools the combustion chambers so much better, that you can actually run a little bit higher compression!Anyway, I know this isn't really
an answer to your question, but you did say,"any input appreciated".Anyway, this is the only time I've ever seen a magazine article specifically mention plugging the water pump bypass on a small chevy, so I thought I'd mention it.For more info on Evans NPG, go to:http://www.evanscooling.com/main31.htm
Hope this Helps-
-Rich-

 

Ive read about doing this mod in TPISs propaganda, and was planning on doing it on my next engine buildup, but if Im not mistaken they reccomend drilling small circulation holes in your thermostat (cant remember exact size) to prevent air pockets when pluging the recirculation hole. Im not sure exactly how much this mod will help, but a little is better than none, especially when it's free!

 

Yes, I've done this mod-but also put in an Ed. hi-flo pump at the same time; so I can't say for a fact that that mod. alone would make as much diff. as I noticed by doing two things at once. But- a big FYI!!! I tried the standard thermostat with just the holes drilled in it as suggsted by TPIS-it overheated!! I finally figured out that I had so much pressure that it was pushing the thermostat closed-even with the bypass holes drilled. I had to put in a "balanced" hi-flo thermostat for a few $$ more-then a big diff!


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86 406

 

Thanks for the info guys, that evans cooling is very interesting, I'd definately like to try it some day...

I've pretty much decided to try this, since I'm using a high flow drilled stat it should be OK.