|04-03-2013 03:49 PM|
The small bypass hole is really a flow balance hole, that combined with the short pump could result in that side seeing too much flow at the expense of the driverís side. The natural spin direction of the pump tends to favor that happening. The short pump is worse about that than the long pump.
The hole you plugged on the top of the pump leads to the suction side; it functions as the bypass return to the pump in a normal street application. The Gen I SBC can be a bit fussy about this when it isn't hooked up.
The intake gaskets you have allow the option of drilling and tapping the rear of the intake for a return. Such a return helps keep bubbles from forming and becoming trapped over the rear combustion chambers. Many racers run what is known as 4 corner coolant return for this reason. The rear return's don't need to be large about 1/2 inch is plenty, you're after some circulation, but not a major return as that would deprive the forward chambers of coolant. The center hole is for an exhaust cross over to heat the intake. OEM heads for carbureted and TBI models use this hot spot to force vaporization of fuel and to prevent ice buildup under the carb. Port injection and high performance engines don't need this so OEM Port injection and most aftermarket heads do not have the passages from the center exhaust ports to feed the cross over.
High flow pumps can overwhelm the system they are really designed to be operated with an under drive pulley to slow them down, this also helps improve left to right side coolant flow issues. However, some racers block off about a third of the right (passenger) side inlet hole. It is helpful to run dual temp gauges from the near center tap on each head, good gauges that can be read within about 5 degrees so you can actually see if/or what the temp differences are side to side. The idea behind high volume pumps was not to simply put more coolant through the engine, but to reduce the high RPM power consumption of the pump by obtaining adequate high RPM flow by turning the pump slower. The typical OEM pump at high RPM delivers far more flow than is necessary to cool the engine which consumes a lot of power for no valid purpose. So with this type pump look at under driving it by 20% crank RPM.
Yeah water wetter doesn't have that big of an effect on temperature but being a foam-less detergent it breaks the tension between water molecules. This allows them to better saturate surfaces making the coolant better able to transfer heat. I think the reason you don't see much change in temperature when using water wetter is that it not only is better able to transfer heat into the radiator's structure, but it is also picking up more heat from the engine's internal surfaces, so the net temps look about the same to the gauge, while the area of hot surface cooling is improved through fuller contact with the coolant. So I wouldn't say the stuff doesn't work it's doing something beneficial for which it doesn't get any advertising press because the process is too subtle to sell by shouting.
Is your compression ratio a DCR or SCR number, I think it a bit low for an SCR with the Lunati cam this kit includes, especially with aluminum heads.
To that thought, I'd add that this could use more initial advance with an equal amount taken out of the centrifugal, like about the reverse of the static to dynamic you currently run. No vacuum advance makes sense.
|04-03-2013 01:29 AM|
To me it looks like you have most (if not all) of the bases covered. Yes, your motor plate will block a LOT of airflow, but lets face it - underhood airflow is NOT a streamlined, smooth-flowing thing anyway.
The combination of big motor plate and no inner fenders, combined with turbulence from wheels spinning in the airflow means all bets are off in terms of predictions regarding efficient exhaust of cooling air from under the hood.
However, your biggest potential trap will be ignition timing. Being either too advanced or too retarded can negate just about any other factor in temperature control.
|04-02-2013 10:57 PM|
|vinniekq2||Is the radiator a dimple core?|
|04-02-2013 07:50 PM|
Comprehensive Cooling System Pre-Evaluation
You probably clicked on this thread thinking 'yay, another my engine is over heating and I need you to fix it for me over the internet thread'. Let me assure you that I am not starting this thread with that hope in mind. I want to have the experts on here pre-evaluate my cooling system set up before the car is on the road.
Before you tell me to search, I'm pretty sure I've read almost every thread on the cooling topic in the Engine forum. One thread was with a guy who had an old Scout that was running hot at cruise, and it was about a 20 page thread. I read it start to finish, took notes, and was amazed at how many people threw in some grand-plan suggestion for the guy 8 pages in without even reading from the start. With that in mind, I'm going to give a detailed rundown of my car in all the areas that I have learnt affect its cooling capacity. I'm going to throw out a few specific questions. If you actually take the time to read and digest my questions and background info, I would MUCH appreciate your feedback. Feel free to be an *** and as sarcastic as you want as long as you're giving me real information.
VEHICLE: '88 2door 2wd S10 Blazer, back halfed, tubbed, caged
ENGINE: 383 only broken in on engine stand, holley systemax head-intake-cam combo(300-503-1), eagle rotating assembly with -18cc dish pistons, felpro 1003 head gaskets, CR of 9.2:1, Powerjection iii fuel system, msd6a and Summit MSD knockoff distributor, planning on running 14 deg initial and 36 deg total timing with mechanical advance only
TRANS/GEARS/TIRES: built TH400, TCI 241002 10" converter, 4.10 gears, 31" tires
I'm attaching pics so you can see what we're working with.
1.)The radiator is a Howe aluminum, crossflow, the CORE is 32"x17", 10 fins per inch, 2 row. The core is 3" thick, I'm not sure on the tube size but they're between 1.125" and 1.325" so we'll go with 1.25". Big enough?
2.)The fans are electric 14" blade 2500cfm/fan. I'm controlling them with a Flexalite controller that ramps them on from 60 to 100% duty cycle proportionally from the set_temp to set_temp+10degs. Big enough? Oh I'm running a 185 t-stat.
3.)The shroud fully covers and it's side walls are sealed to the rad core but is only 1" deep due to space limitations. I'm debating putting a flap in the shroud for cruising airflow, but the fans cover 95% of the suface area of the shroud/core so I don't think I would get any appreciable air flow gains at cruise with an added flap. What do you think? How crucial?
4.)As you can see, I eliminated the stock wheel wells and ran sheetmetal plates from tabs on the fenders over to tabs on the front rollcage bars. I'm expecting this to aid in getting hot air out of the engine bay. The blazer sits low to the ground and I'm using the factory air dam. Expecting this to aid in low pressure zone creation in the engine bay. These two things help me get hot air out of the engine bay, but I'm wondering what your opinions are on the effect of the front motor plate inhibiting exit of hot air from radiator during cruise? Motor plate comes up to bottom of valve covers and goes down to mid line of crank pulley.
5.)I'm running an 11"x11" plate and fin tranny cooler mounted right to the rad-core on the outside. Cooler is blocking part of the rad core right in the rad support opening but I don't have anywhere else to put it
6.)50/50 green anti-freeze and water, with a bottle of water wetter. Waste of money?
7.) The pump is short weiand 9208 high volume, driven with the belt setup you see I threw together. Pulley's are either 1:1 or a 10% pump overdrive. I can't measure for sure right now. How's this pump and pulley combo fit the bill? See the blue aluminum pipe plug on top of the pump, is this a suction or a pressure port? Should/could I use this as a bypass from the front of the intake manifold to this port on the pump? I'm thinking I need more bypass flow cause I got wierd temp spikes and fluctuations on the break in stand. My break in stand has a radiator and taurus fan. (OldBogie I need your advice! ) If you're wondering, I drilled the front motor plate out for the passenger side little hole on the water pump horn/engine block.
8.) The intake manifold is a holley street dominator It has no rear water crossover. The intake does have a middle crossover as well as the mandatory front crossover where the thermostat resides. I'm confused though because the intake gaskets (felpro 1002) that holley suggested using with the systemax kit have the rear coolant opening in the gasket where the intake manifold blanks it off, but do not have a coolant opening in the middle of the gasket where the intake manifold does. Am I allright with not having coolant crossover flow out of the rear ports on the heads? Should I cut the intake manifold gasket to open up flow to the middle crossover in the intake? Check out the attached pics.
Thanks for reading erbody! I appreciate it!