New 20v Rwd Cooling Guide

[Sam_Q]

hey guys I have spent an insane amount of time over the last year and a half writing this:

 

Sams new 20v cooling guide

 

Suggestions and feedback welcome, particularly for grammar errors, english isn't my forte. I will post this to the other forums as well.

 

 

Disclaimer: I have this on my own website which has parts for sale. In many parts of this guide it uses pictures of my own parts. This is because I was the owner of these pictures and it's what I had available. I where possible included photos of other options and talked about whats good and bad with each option including my own. I did not write this guide for financial gain, even if I did it would be stupid as I would never get the money back in proportion to the amazingly huge amount of time to write it.

 

Sam-Q

[beerhead]

I'll have a better read later, but for a start I'd think about making a proper Table of contents at the top of the page that gives you hyperlinks to the information down below, I'd even split the page into smaller pieces to make it easier to find information.

 

I do wonder what Yager would think of your "new" top water outlet too... naughty naughty, I suppose these sort of things can't ever be patented but in this industry you should be careful who's toes you step on, I can still remember the Kellam vs SamQ debate on the old driving club about the block off plate :hmm: Wasn't a very dignified debate on either behalf.

 

I'm not too fussed on that brass barb outlet on the top pipe either, looks like it'll be a mission to link it neatly to the pump, similar to the setup like Niz's car. I see that pic also has a thermostat housing on the top and the bottom, slightly confusing, because the advantage of a Yager style top outlet is you can leave the bottom half standard.

 

I've seen the warmup cycle of Littleredspirits car on the Yager kit too, I was slightly concerned without a bypass at the beginning, but just set a cold rev limit, and you will see the gauge do a couple of cycles as the thermostat opens and shuts twice within the first 5 minutes of driving and then she's warm and good to thrash.

[Sam_Q]

A table of contents is very much a must, as is more clearly defined sub-sections I think.

 

With the top outlet you mean this?

 

 

I just can't see it as a copy of any kind. I am just using an adapter plate to use an existing water outlet pipe (albeit modified) to be a new outlet. The yager is an all in one solution to an a top outlet and thermostat with no bypass pipe, something I don't plan to really do under normal circimstances. This one above is just an outlet, no thermostat and has a bypass line which is designed to be used with an external thermostat. I went this way because it saved me making something from scratch as my fabricated effort really sucked. I also just can't see how I was undignified with that debate over the rear plates, that was more of a misunderstanding than anything anyway. Now that I think about it I want to put a pic of that Yager outlet on my guide as well if it isn't there already, it deserves more credit than it gets.

 

 

Heres a pic of that outlet on the head:

 

 

as you can see it's very much not intended to be hooked up to 4ac rear pump. I from the start had in mind for people to use an external thermostat as it's the easiest option. I at this stage am not really keen on making another fabricated outlet that does suit these pumps as there isn't much demand for it vs the time needed and personal cost on my end. Oh yeah and the whole not enough time to scratch myself thing, hence why I had to wait till a Sunday to answer this post. It's one of the many things that in the future I will consider.

 

On Niz's car it should of been a simple 90 degree bend in the hose, probably using the hose off a VN. Either way that outlet is not as good as it should be and just for the record he is getting something new or his money back.

 

It was Matts engine I was refering to when I said "apparently there is no issue not using a bypass". I only used the term 'apparently' because I avoid quoting other people information that is given to me as fact, even if it is from a reliable source like here.

[LittleRedSpirit]

Just like Brad said, there is no issue with not using a bypass, the waterpump is capable of backflow, but an important point is that I use an underdrive pulley in combination with it. For safetys sake I have a cold rev limit of 4000rpm until the water temp is over 40 degrees centigrade, shortly after that my thermostat would open (at 72 centigrade).

 

As Brad said it would generally cycle open then almost closed twice before it was warm. Depending on conditions it would take 5-8 minutes.

 

If we strip away all the things about cooling systems that pertain to emissions tuning for adr compliance, a bypass isn't strictly necessary. As far as thermostat location goes it needs to be somewhere that it can absorb and soak up heat from the block or head, not just rely on the water to transmit the heat. I feel that this leads to hot spots, and more wildly varying temperatures from a slack thermostat response. For this reason I feel its a bad idea to run an external thermostat on a 20v (or any engine). The remote thermostat allows the head to get too hot before it opens. I could tell this from my coolant sensor readings and also the sound of the thing, as well as the massively variable coolant temps and the constantly cycling thermostat. The constsntly cycling thermostat was real concern, because the water temp sensor in the head said it was hot, borderline too hot, but the thermostat still wanted to close. It had a different bark to it when it was full hot, sort of like it was almost overheating when I used the external thermostat. If you think about it, Toyota has placed the thermostat at the rear of the head. There is no coincidence that this is where the water exits the motor. That is why the yager fitting is also very good. It is best practice to have the thermostat at the outlet point for the water from the system.

[Sam_Q]

interesting, so you think the 16v engines where a bit of stop-gap measure instead of them having to redesign the head?

[LittleRedSpirit]

interesting, so you think the 16v engines where a bit of stop-gap measure instead of them having to redesign the head?

 

 

I don't know about that. As far as I know it was the 8 valve 4as that had the remote thermostat, did the fwd bigports also have it? I cannot remember for sure, but I think I remember seeing it in an AE82 twinky.

 

I'd be uncomfortable saying Toyota did things wrong, as I'm sure they did what they did for a reason, and with far more science and purpose than what we have used in our modifications. I don't strictly know what their rationale was, but I dare say it was based around a fast warmup to reduce emissions when the car is enriched while cold. For emissions reasons most manufacturers run a bypass to reduce warmup times.

 

Wheres the thermostat on a 16v rwd engine? I can't remember having never worked on one. I seem to remember its near the waterpump somewhere but I can't really recall.

[Sam_Q]

the 16v rwd one is like the 4ac, any fwd 16V 4age had an external thermostat

 

the 4afe and 7afe engines had a 20v style thermostat

[beerhead]

Ah I get it, at first glance I assumed there was a thermostat hiding under there. All this talk about hot spots makes me want to buy a laser thermometer to check if there's hot spots at startup until the thermostat opens, the only sure way to tell.

[Sam_Q]

yes I can see why it externally looks like a simular product.

 

I would of thought the hot spots would be around the inside of the bore where there would be no way of knowing?

[beerhead]

Yep, the hotspots will be internal, but if there's insufficient coolant flow the the coolant would be hot in those areas, and the external casing of the head would show a variance of heat across the casting. My guess is the jiggle valve on the thermostat would let enough coolant pass to allow the head to circulate enough water to keep things happy. Yager uses this on track proven 200hp 20V's so it must work ok.

 

I guess on a street car it's a good move to replicate the factory warm-up system, but seeing Matt's car has run flawlessly for craploads of Km's I have some faith that it's non issue with a sensible driver.

[LukeAE71]

I ran the no-bypass system for 5,000 k's plus in my 20V - no issues :P