water flow problems with v8 conversion

[roywb46]

We are working on a 1970 Porsche 914 with a 1961 Buick 215 v8 installed. The radiator is obviously been placed up front. Having a big problem with constant water flow pressure. The thermostat has already been removed. Thought about an external electric water pump but pretty spendy but may be the only option. Approximately 5-6 feet of hose travel involved. thank you

[Rotary'14]

Why do you suspect a water flow problem? I guess it's overheating,, but how? At idle,, or after a steady load?
If you can't maintain a good temp at idle,, I suspect air pockets in your coolant lines. Have you tried "burping" all the air out of the coolant lines?
Also do you have a good working coolant recovery bottle? If you can drive your car and it eventually creeps up in temp,, you can do is try "redline water wetter" or any of the knock offs,, this alone is usally good for about 10~20 degrees F.
Lastly,, you should make sure the air ducting in the front goes thru the radiator and not around it,, this also makes a big difference.
Another method that will improve coolant flow is to DECREASE the coolant line diameter if that's truly your problem


Good luck with the project.
-Rob

[John Rogers]

Can you post a pict of the from mounted radiator. I have seen a couple of conversions in 914 and also a couple of Mazda conversions to big ass Chevy V8s and all had cooling troubles until they got some well made ducting. The best place to get air is from the middle of the front bumper area and exhaust it either out the bottom of the front trunk or out the sides behind the front wheels. There has to be ducting though so the air will not just go in and and wander around and build up air pressure in the front trunk space.

As for cooling line size, search here and on the Pelican site for other conversions to see what people use. I know with front oil coolers that larger sized lines are better as the have less resistance to flow so the internal engine oil pump can move the oil easier. Oil pumps are a positive displacement type but the water pump is usually a centrifigal pump and they also like less resistance (less head to pump against) but then again I have never owned a water cooled Porsche!!??

[roywb46]

Vehicle originally had coolant temp gauge at front in radiator which was useless, we relocated a coolant temp gauge on motor which provided more accurate feedback. Vehicle was burped properly and appeared to get all air pockets out. At idle and while driving a short distance the temp kept at the 190 degree range which is acceptable but after driving over 10 miles the temp went up to 220 and above and the vehicle started running rough until engine cooled back down again. Have good electric fan on radiator, which runs both when the temp reaches 150 degrees and above and keeps running when vehicle is turned off until temp is reduced to lower levels. Radiator is located downwards in front trunk area with air forced coming in from below front end and from interior cut our areas in front trunk. Thermostat has been removed for added water flow. Thanks for the comments. Roy

[Rotary'14]

Judging from the description of your radiator set up,, I would say it sounds like you have an air flow problem instead of a water flow problem. You need some "ram air" effect to push the cooling air into and thru the radiator. An electric fan can only move so much air,, (just enough for off idle if you ask me). As you put a steady load on the engine the temps will climb. As John Rogers suggested,, the ducting in the front is VERY important. Not only is a good ram air inlet important,, but you also must make sure the air coming out of the radiator doesn't have any problems leaving the car. If the cooling air doesn't exit well, you will get a high pressure area behind the radiator and prevent air from flowing thru the radiator.

-Rob

[rschroed]

It is a myth that removing the thermostat improves cooling. It can actually allow coolant to flow through the radiator too quickly to benefit from the cooling airflow. Try putting the proper thermostat back in.

[rich]

Put the "T" stat back in. Drill an 1/8" hole in the flange so any trapped air can burp out from under it. The be sure to check your air flow. Be sure you not just cycling the hot exuasted air back into the front.

Post some pics of your radiator set up. I think you have an air flow problem

[pizza914]

These pics are of the old on. There is a new aluminum one in its place. It really was just a temporary fix as I was on a trip when the old one gave up the ghost. This is basically an 18x18 radiator at an angle. The cutout runs from just under the front bumper back about half way thru the bottom front trunk. I planned on going to Renegades newer setup. Just don't have the dough yet. Roy who started the thread is my wrench & a good one. We are both learning with this buick 215

[rich]

You are cycling the air from the trunk back under the car . There is no way it will ever cool like that. Not to mention your pulling the air from the hottest place, the surface of the road.

[rich]

This is a very old photo of my setup. I can't find a recent one and I'm not able to get a picture now. Note my cut outs are very small. The frontal area of my radiator is completely sealed from the outlet air. There is considerable space between the inlet and outlet air to prevent cycling.

[914GT]

Assuming you're still checking this thread here are some additional suggestions.

1. Make sure you're getting all the air removed from the radiator. Best is to have a petcock at the top to open while filling the system until no more bubbles escape. Don't know if your new aluminum radiator has this provision.
2. Make sure hoses anywhere in the system are not collapsing once they get hot. An almost-kinked hose will soften with heat then further restrict flow.
3. As Rich suggested get the thermostat back in, with a small bleeder hole. Removing it will not help and can screw up how the coolant circulates in the block during warm-up, creating hot spots.
4. You should have started with a clean block and heads free of corrosion and deposits. An old dirty block can release crud and plug up the radiator, and have poorer heat transfer to coolant.
5. Check the engine timing and idle mix. Too advanced and too lean will run hot.
6. If you have an aluminum intake with exhaust crossover under the carb, consider blocking it off or adding restriction to reduce heat transfer to the temp sender and carburetor. The airflow in the 914 engine bay is poor and the carb can heat-soak and exhibit vapor-lock or flooding from secondaries spilling over.

I've got a mildly-built Chevy 350 with air conditioning, and drive it here in Tucson where it gets pretty damn hot. I run an electric pump, 180 deg thermostat, and 3/4" steel pipe under the car and have no problems in city or highway driving.

[pizza914]

I am defiantely still checking the thread. Thanks for the nice step by step. I am going to get a nice dual pass 16x31 radiator. I'll have to see if they can add a petcock for me. I'm also going to go to an Electric fuel pump. I'll update as I get things. It is doing better staying around 190. Still will creep up on super hot days but it takes at least 20 minutes of driving before it will go over 190. Then seems to slowy creep up from there???

[marks914]

There is your problem, no airflow .
You might get that setup to work of you duct some air to it and seal it really well.
Which way is the air going? In the trunk or out?

Mark

[pizza914]

I finally decided to just pony up the dough for a proven system. I should get it in the next week or 2 at most. I'll let you know if I have any problems after I get it installed. Thanks for all the tips.

After talking with Scott (I think) from Renegade I am seriously considering an LS1 swap down the road. I'll be in Vegas in another week for a convention. Planning on going by Renegades shop & picking their brains while checking everything out.

[rich]

Scott's a good guy. I've been to his shop with the Alien. He didn't have much good to say about my 928 powered 914 but he has several proven parts for sale. If you can't figure a way around you problem sometimes throwing money at it works.

[amac914]

Hi Rick

Can you upload or provide a little info on how large your opening is in front of the radiator?

I am having a similar issue. I have a 74 914 with the v8 conversion, with Renegade Hybrids kit. The issue is on hot days, it will get to 200 or 220. It does have a pretty high performance V8, should be in the range of 330 hp from a 305.

Timing has been done and had to replace the water pump. Wondering if I should have gone with a hi flow one or if I need to look at a electric water pump.

The radiator does have duct work. I can upload pics if that helps.

[rich]

[rich]