My 1st 914-V8 back in 1979 had a 916 fiberglass front end that had a smaller opening than you show on your car. It only had fender openings the size of yours. The car was flared with 8-inch wheels up front. It had a aluminum radiator from a Corvette leaned at an angle so it would fit in the car and I made a sheet metal shroud for it and it used one large Jaguar fan. Nothing that fancy. This was back in 1979 when a V8 in a Porsche was somewhat rare. Not a big HP car just a 283 with carb and cam and headers. Trying to understand your airflow and comparing it to my old car.

I ran gates green stripe water hoses through the heater tubes, a Rob Simpson water pump housing and water pump from what I remembered was from a Mopar Big Block. The sealing on the shroud was not that great and a lot of air flower around the radiator as well as I remember that the car got hot inside as well from the hot air. I drove it with the top off or the windows down, I did not run a thermostat on it.
It did not run cool but 200F or so was what I remember as the norm for it.
This was in Los Angeles area.

Not sure if you are chasing what may not happen in your car. I would not cut anymore metal out of your car.

Bob B

This evening, I finally had a chance to take the car out for drive without the hood and the front bumper. Temperature was around 80; skies were cloudy (minimal sunshine); winds at around 9 mph from the north and 30% humidity.

What can I say... this was the longest I drove my car (around 10 miles with speeds approaching 60 but mostly in the 40s and 50s) and the temp never went beyond 185! Usually, I would drive half that distance and my temp would be closer to 200 or higher.

I believe I can honestly say that I've narrowed down the run hot issue to either not enough air passing through the radiator or not enough air exiting the radiator and front hood cavity via the inner fender walls. It might even be a combination of both.

If the restriction is on the inlet side, I do not know how I can increase the area of the grille opening without hacking up the Chalon front bumper. Any tips/ideas?

If the restriction is on the exhaust side, the inner fender walls have been opened up to their max size. I suppose the next logical thing to do is allow more air to escape via the floor of the trunk... drill some large size holes? Next might be to louver the hood itself.

I have not completely dismissed the idea of going to an electric water pump and I do want to hear back from David to see how his Jegs electric WP mounted in his remote WP housing works out, but my testing and results are also hard to ignore and right now it looks like the problem is air flow in and/or out of the radiator!

Discuss, discuss then speak up!

Thanks!

You need to do scientific testing.

Map a route, Determine OUtside air temps. Drive route without bumper or hood, Then drive it same temp without hood only, and finally without bumper only.


This will ID where your problem is.

I was just looking at your build thread and question the airflow from the front. Have you tried removing the front license plate? If that helps you may also open up some of the fiberglass on the bottom of your bumper and see if that helps with more airflow. If I remember the front of the Chalon kit was formed from a 74 on front 911bumper and a turbo bottom valance rubber trim.

Not sure that you showed us the amount of metal removed on the factory 914 nose.

It seams that you need flow based on in flow through the front and out flow through the fenders, see what the sq. inches of cut outs you have leaving and SQ inches of cut outs for inflow. Somewhere there is back pleasure where it is not flowing. I do not think opening up more holes in the fenders will help you.

Bob B

Hey Bob,

Good questions!

Removing the license plate was one of the first things I did and I think it helped a bit... perhaps more than a bit but there were other things going on too.

I followed the Renegade manual in regards to opening area versus exiting area (I do not have the numbers but I will get them later) and was able to meet the recommendations.

I think I can open up the bottom of the Chalon bumper but need to really look at to see if I can duct it to the bulkhead correctly.

I'll get that info this evening.

If you have the same setup as everyone else then that's not your problem. You are either generating more heat in the engine (running lean) or you are still burping the system.
First put the hood back on and go for a drive then report back. Next day put the bumper back on and report back.

I did some work on a 2000 Jeep Grand Cherokee yesterday. The car idled at a steady 200f without the fan even on. It needs to be asked, what temp do you think is right for your 914?

Hey Chris,

I understand... I am quite certain that my setup is similar to what others have (perhaps even a bit better) and I have tried to follow the Renegade manual, and that is why I am struggling with this. On one hand, I have parts of the Renegade Kit like the WP housing and the mechanical BB Chrysler which should work... they are from the kit manufacturer! On the other hand; it seems that many of the owners of similar conversions have switched over to electric WP's for the same reasons and concerns I am having.

I have a mild cam installed with headers, dual plane aluminum intake and a 650 cfm carb. I do not think it is running lean... the exhaust tips have black soot and on them and my gas mileage is really bad... like very low teens to perhaps even high single mpg's.

What is a normal operating temp for my car? IDK. SBC do not like anything above 230 degrees and mine has been there there or awfully close many times in the past. I start to get worried whenever it goes past 210 (sensor is installed in intake port right next to t-stat).

Perhaps now that the expansion tank is working correctly; I have not given it enough time/cycles to correctly burp the system.

That was my thought process... start with re-installing the hood and see what it does, then move on to re-installing the bumper. I'll let you know what I find!

So with the hood and the bumper off, I decided to remeasure all of my openings to make sure they matched what Renegade recommends. Although Renegade does not make a recommendation for the bumper opening, they do recommend a minimum of one square foot opening for the front panel. I suppose the same recommendation would apply to the bumper opening too. On the outlet side of things, Renegade recommends a minimum of 120 square inches per inner fender opening (side). My Renegade manual is dated July 1990.

My measurements? Well, my grille opening is a measly 105 sq inches (around 0.73 sq foot)... below Renegade's minimum. My front panel opening comes out to 158.63 sq inches (1.1 sq foot) which is slightly over minimum and the outlet areas are 154.25 and 144 sq inches respectively... again slightly more than recommended by Renegade.

It would appear that on paper anyway, my weak link/bottle neck might be my grille opening size. It is also the hardest part to open up and still have it look decent.

I did notice that where my opening on the front panel is strictly on the vertical surface, Renegade did open theirs below the vertical side... and cut into the floor/horizontal surface. I need more grille opening area!

Go ahead and toss that out. That is before aluminum radiators and good electric fans. That's also before the new owners in 2000 changed everything, so you can't refer to it as "the" Renegade setup anymore.

My air inlet is 97 sqin and actually over cools at highway speeds.

You need to go test it with hood on bumper off before coming to conclusions.

I thought the car did 190 with the new bottle?

What are the temps at idle, stop n go, and freeway? Each scenario is a different condition.

I used to do engineering for RH. I didn't get lucky, I actually crunched the airflow numbers.

Nice!

Anyone have a newer Renegade manual they would like to share?

195 max (so far) with the new bottle and hood/bumper installed.

Last night; I looked at my overflow bottle and the system actually drew some water back in after my drive without the hood and bumper 2 nights ago. I don't think it sucked in any air but it did get kind of low. Looks like the dang system is finally working!

This weekend is supposed to be in the 90's. I'll start by installing the hood and taking it for a ride (of course jot down all pertinent info) and let's see what we find!

After carefully inspecting my radiator area, I made an observation and am now wondering the affects of having my rad set up the way it is. Notice that I have the rad positioned with the top of it resting pretty much against the front panel (resting on a flat bar going across the top). Seemed an easy way to mount it. But; I have noticed most others mount theirs so that the top of the rad is resting further back and away from the front panel. Most then create a cover/shroud to cover that top space. Mine has no space on the top side of the rad, between the front panel and the rad. Would that extra space on the top side of the rad be beneficial to the cooling efficiency of the system... perhaps acting as a cooling plenum or chamber?

Here in Boyzee; I've either been busy at work or it's been downright cool during the days so it's been hard for me to test during a hot day. For example right now; it's cloudy and it's in the high 50's and it's even snowing in the Sawtooth's... go figure.

I want want to perform my driving tests but I also want to put the bumper back on but what about the radiator positioning like I mentioned above; is their any validity in the observation?

Click to view attachment

I had my radiator setup the same way (Tilted forwards) and didnt have overheating issues from it.

Mike Bellis had his radiator laying flat against the floor on his old v8 car...

Your rad position is fine. The Corvette and 300zx actually lay flatter.

195 is fine.

Water expands when hot & shrinks when cool, so the reservoir is supposed to get fuller and return to the starting level. If it keeps getting lower and lower you are still burping air or you've got a leak. With the 914s funky hi-lo-hi system it's not uncommon to top off several times after the first dozen drives.

I put the bumper back on yesterday and drove it for a while and it stayed at around 185. It was a cool day... around 70 when I drove it.

Assuming things will slowly get better as you mention; it begs the question... how many out there continue to use a mechanical pump and how many have switched to electric and why the change over.

I had same issues.car would shoot up to 200-210 within 10 minutes I would bet your whole issue is trapped air.not shrouding!
Once I got my "air" issue fixed I haven't had a problem since!
Runs about 180 -185 all day!
And I burp it frequently.

I've had a remote electric pump since I built the car in 2002. Went that way for a few reasons. There were claims an electric pump would not work so I like a challenge. And at the time I could go with an electric pump for less money then a belt-drive pump. Finally, the electric pump offers more flexibility on location and simplifies things by eliminating the brackets and hardware needed for a belt drive pump. I've been very happy with it and no problems after 15 years.

Got to work on the car last weekend. Just returned from China. Still have jet lag so didnt work too hard. Finished the wiring and took it out for a test drive. Temps were in the high 80s. On open road temps were 170-180. Setting in traffic after drive temps got to about 205. Still havent really purged the air completely. I feel the Jegs pump so far works as well or better than the Renagade pump.
David

David,

Welcome back and glad it's working out so well so far. Let us know how it goes after a few run cycles.

It's been cold and rainy here, pretty hard to test hot weather performance. Funny thing is usually around this time of year, it's like 100 degreed out, no clouds and very little humidity. Darn El Ninia!

Around 20-30mph the airflow from moving becomes greater than the airflow from the fans. Might not be air bubbles but an insufficient fan cfm. Still, 205f is not a deadly number.

Chris, You may have mentioned this earlier but do you run a mechanical or electric WP?

I will try to purge the air better this weekend. I have the complete Renagade system so I think the fans are rated correctly. What I dont have is shrouding around the fans. They didnt do it when I bought the system . May mock up a shroud as well and see what happens.
David

Dave... update please! What are the results of your upgrade so far?

As for me... so far so good. Drove it to work (10 miles one way) and back and it barely broke 200 and it was a warm day too!

I see this thread is several years old. I’m just curious if this ever worked out with the electric water pump does anybody have any input?

Used the Jegs pump with my Renegade housing. Had to machine the housing (.100 ?) to allow the pump to fit.
Changed to Mezier with the LS.

http://www.914world.com/bbs2/index.php?showtopic=363404

Here is an example of electric water pump.

As well as a V8 car for sale from one of our fine members

Bob B

Click to view attachment

Thanks for the reply, when you did run the Jegs unit did you have enough flow or any cooling issues ?

Looks good Bob, I have heard the Davies-Craig is a good option, I’m trying to retrofit without any major reworking of the system. My current belt driven unit works fine but I know the Rod Simpson housing has a restricted inlet. I’ve reached out to Renegade to see if they will sell a housing I can use the Jegs electric motor. I’m also trying not to create more problems by messing with the already functioning system.

Yes if I recall it worked better as didn't depend on engine speed for flow rate.
Didnt use very long as was in process of upgrading to the LS renegade system

Thanks !!! Any chance you still have the Renegade housing ? For sale ?

I clearly remember the rod Simpson water pump housing. This was back in 1979, it fit a 440 or big block Mopar water pump some guys said they had to the machine the back a little bit because when you pushed a stock water pump in, the back of it was hitting the back wall of housing. It needed to be clearanced a little. My memory, that of a 70 year old dude


Best Bob B Burton