I've read on the Forum that DeWitts sells a C4 fan adapter and although I've searched for a description, I can't find whether it's only for pre-LT1 application or what it looks like. Does anyone know the answer or have a picture? Thanks. John

 

 

You should contact Dewitt's directly and ask them.

 

Thanks, John.

 

I don't believe it's an adapter but rather a SPAL fan package for either '84 - '89 applications (single puller fan) and a '90+ which is a dual fan puller assembly. Use their web pages and I believe when you select the correct year car the proper fan package will be displayed as an option.

'89 and earlier cars had a vertical radiator with a single puller/aux pusher in front of radiator as an option and the '90+ the "slant back" radiator with no pusher but ALL had the dual puller fan configuration.

If by adapter you meant something else I'm "LOST".

 

Thanks for the reply. In fact it is something else referred to in another thread (Post #13). I hoped someone had bought and installed one but I may just have to call DeWitts as enventr suggested. John

 

Might make a difference if you mentioned "which car". I'd think the one in that post might have been intentioned for an early car but you've mentioned recently a '94 car maybe. Your ZR-1 is sold I thought.

If it's for a later car the needed parts are part of all current shipped kits. The adapter you're looking for or thinking about is maybe mentioned here or in that thread.

https://www.corvetteforum.com/forums...post1561465148

 

Thanks for the follow-up and yes, it is for my '94. John

 

I have the Spal fans in my '93 I bought from DeWitt with the new single core radiator. Works great!

 

You mentioned adapter, which I think you may be referring to a plastic spacer used to mount fans to radiator cowling about 3/8 of an inch thicker to space fans from touching the stock radiator. Did not need them with the new radiator. I would have to look in the installation directions to confirm that.

 

Thanks, Scott. I've called DeWitts but haven't heard back yet. What I understand from a few mentions in the Forum is the adapter is a plate with a cut-out for a 16" fan but whether it is intended for early C4's or later (like my '94) or is even still available is what I'm trying to learn.

Going back to your previous posting, before your DeWitts replacements were you experiencing overheating and under what conditions? Mine is very puzzling as it occurs sporadically like this morning in 90° ambient heading home from the grocery. Every single part of the cooling system has been replaced (including the radiator with a new AC Delco), the system flushed, the debris cleaned out and the fans set to activate at 198° and 205°.

John

 

I blew a head gasket after I failed to double check a hose clamp when I put in a new optic spark and waterpump. Just wanted to not have any problem again and the assurance of having better cooling. It was interesting to watch the temp gauge last year as I was headed to a car show and was in a 12 mile construction zone that took almost fours to get through. It was 85-87 degrees and as the tempgauge rose, first fan would come on and as it reached the temp the second would come on and that really brought the temp down. I don't thin the OEM radiator or fans would have done that. I know I passed 8-10 vehicles off to the side of the road with the hoods up!

 

Thanks a million. John

 

I THINK the SPAL fan adapter is part SP012. I also believe it's pictured on this webpage... (It's the silver ring around the edge of the fan.)

http://www.dewitts.com/collections/s...te-fan-upgrade.

FYI: I believe our early model fans are 17". That adapter fills the gap between a 16" SPAL and the mounting points (or, at least, the shroud) on early radiators. This part wouldn't be valid for late year C4's because they converted to dual 11" fans. That said, DeWitts sells SPAL upgraded fans for late model cars.

I have been thinking about this mod for too long. FF Dynamics sells an alleged 3600 cfm fan that's the highest I've seen advertised. Another member swears by it. Derale sells a nice SPAL-looking 17" fan I've considered. It's two speed that might just work with the stock main/aux fan circuitry (load) and go in w/o the need for an adapter.

 

Many, many thanks for getting back to me Gregg, especially with that info on the DeWitts fan adapter.

Like you I've been wrestling with what to do about heat and with predictions of our temps climbing over 100 late this week (and probably staying there) it's on my mind again. My beginning point is there are two important considerations to begin with - first, in 2015 we're dealing with higher ambient temps from a variety of causes including more and slower stop 'n' go driving than when these cars were designed and built 30-40 years ago and second, despite the most rigorous maintenance there's some degradation in the cooling system of every one of these cars still on the road.

I've looked at the range of possible solutions over the years and this year decided to ask a friend whose biz for for decades has been designing, building and racing cars to give me some general guidelines on how he'd go about addressing the problem. His threshold response was when it come to heat rejection he's not focused on minor improvements but instead uses the hammer and anvil approach to go after fundamental and significant improvements. Still he begins with an assumption that everyone is running the minimal ratio of coolant/water and preferably 100% water with corrosion protection.

He differs with those who view multi-core radiators as a panacea, pointing out that if the radiator is made thicker, the mass rate of air flow decreases. Even if the thicker core flows well the back half of the core is subject to the ambient air that got heated up in the front half of the core. This actually means that the back half can only do 1/4 of the heat transfer. BUT, it can't reach that as the thicker core will always have greater drag and the increased area of just metal for heat transfer will not compensate. So, no thick radiators for him. His view is under two inches; never over 2.5 inches.

The radiator air flow problem is compounded by A/C condensers. Frequently he creates a path for substantial air flow to the radiator that bypasses the condenser, achieving in cruise mode an 18-20˚ temp reduction in one design.

On the other hand he favors helping out the radiator with additional cooling, either through an oil cooler, which can take about 15˚ out of the water (I'll return to this possibility below) or a separate radiator core, often only about 5 inches by 15 inches with a fan.

He also suggests venting ranging from hood louvers to side vents to an extraction hood. I ran an extraction hood in one of my earlier turbocharged cars (not a Vette) and it worked great. On the other hand I notice you have an extraction hood but perhaps it's not the silver bullet you hoped it would be (but it sure does look good!)

Last he says fans are always tricky but can help although it often takes a lot of tries to see what works.

So those are his thoughts and here's what I'm thinking based on them. First, I'd also seen the FF Dynamics fans and think I'm going to try one of those as a pusher in front of the AC condenser. I've read criticisms of that approach including that it just pushes more super-heated air into the radiator but I feel it's worth trying. Second, I said I'd get back to his idea of an oil cooler and think one thing I'm going to try is a separate oil cooler to take the heat load off the radiator. There are a number of models about the size of our transmission cooler such as this one. Only problem is where to put it. Third, I might do a supplemental radiator if the first two don't do the job.

You've made a lot of improvements to your car so I'd sure appreciate your thoughts. And again, thanks for getting back to me. John