Heat

[Jay Jacobellis]

According to our engine guy we are cooking our heads. We run the standard ducts and full tin under the cylinders. Don't have CHT probe yet but will have one for this weekend(what temp should we be looking for on CHT), any ideas what we can do to get more air across these heads.

Thanks

[kea]

Remember that air flow at the rear of the car, first passes by the front.
Anything up there that may be reducing what is available for those heads ?

[BLS]

What Car? Might want to post a pic showing how it is setup.

[Steve Davis]

According to our engine guy we are cooking our heads. We run the standard ducts and full tin under the cylinders. Don't have CHT probe yet but will have one for this weekend(what temp should we be looking for on CHT), any ideas what we can do to get more air across these heads.

Thanks

Jay,
The best CHT sensor that I have found is one that fits under a spark plug. I've been using that type for many years. Overheating is mostly signified by 'bluing' of the cylinder tops ... or possibly other CATASTROPHIC indications. Using a sensor in a different location (fin, head stud, etc) will generally give you a temp indication of something less than under the spark plug. With a spark plug sensor, you should strive to get it below 400F if you can, but below 500F should keep the cylinders from turning color.

Air going into the heads can be affected by things significantly in front of the scoops - like mirrors and front suspension. Do the best you can to have a clear path into the scoops... or move the scoop intakes up or out to achieve that. It's also better to have a clear path beneath the heads - you get additional cooling to the oil by getting air on the pushrod tubes and sides of the case.

It's always a good idea to also monitor the oil temp and keep it around or below 250F for the most part. I don't like the idea of measuring the OT in the case as it's generally well below the highest temp. I measure mine as it goes into the case at the 'bypass' location on the top of the engine. That way I know what temp my bearings are seeing and it's easier to consider whether HEAD cooling is the bigger part of the problem or OIL cooling is more of an issue for you.

As Barry says.. if you post of picture of the car, we might be able to provide more input.

[Jay Jacobellis]

The car is a Murray out of AZ. Oil temp high is 190 at the pressure / temp sensor. I hope I can get these pics to work. can't get the first pic to rotate

[Jay Jacobellis]

lets try this

[Steve Davis]

Jay,
The only thing I see "wrong" at first glance is that your oil press/light sensor SEEMS to be mounted solidly to 'something' that supports it in the horizontal position. From personal experience I can tell you that is NOT a good thing. It'll last for a while, but eventually, something will break ... often leading to bad things - blown engine or fire. It would be MUCH better to support the sensor in some foam (to keep vibration down) and run a short -4 or -3 hose to it from wherever it's mounted. I used to have to replace my sensor 2 or 3 times per year. Since I moved it to a 'foam based' support as described, I've used the same sensor for ... I can' remember how long, but at least since I build this car back in '08.

As for the head cooling - it's difficult to tell for sure, but it LOOKS like the tin stops pretty high on the cylinder fins. I don't use the original VW tin, but my covers extend down to at least half of the cylinder/head fins behind the exhaust headers. I have also used 'diverter panels' just behind or even with the roll bar to force more air under the heads. Every little bit helps .

Get that CHT going and find out really where you stand.

[BLS]

Jay, no expert here, but it appears to me that there are two things that need to be considered. We need the FST guys to jump in here, but it appears to me that you may not have quite enough air scoop area for a 1600 engine. It is hard to tell from pictures but it also looks like the scoops sit at an angle which would decrease the actual opening area presented to the airflow, plus likely cause an aero issue around the scoop which may decrease the air going in.

Barry

[veefan]

This is out of the FST guide , (sorry for the long post)

This can vary by the type of scoops on your FV. Most likely, the FV scoops were designed to cool the 1200cc engine. Some of these designs marginally cooled the smaller engine. There is a strong likelihood that 1200cc FV scoops will not work for the 1600cc FST engine. A very few FV cars do have very efficient cooling and may possibly work for the new 1600cc engine. However, a clear majority does not and new scoops will need to be installed. In most cases, the Universal FST scoops offer by SRacing will bolt directly onto your FV conversion only requiring cut outs in the tail for the scoops to fit. They use stock VW cylinder tin work making the task very simple. If you have to build new ones, keep in mind that the 1600cc engine makes more heat. You need more cooling air delivered to the heads and cylinders, so the duct opening needs to be larger. There are two philosophies on scoop design at this point. One is that the VW factory engineers knew what they were doing when they designed the factory tins. So they use the factory lower tin and build scoops to deliver cooling air into the VW tin. The other thought is to design complete new ductwork built out of fiberglass or aluminum. One generalization all agree with is that about 20 square inches of intake area in clean air is needed as a minimum. Whenever you are developing a new cooling system, it is highly advisable to install a VDO cylinder head temperature gauge to verify the effectiveness of your ductwork. I would also recommend that the sender not be installed under the spark plug. Instead use a second nut and install it on the upper #3 cylinder head stud. That’s the one just behind the intake manifold casting. In that way, the spark plug tension or threads are never in any danger of damage. With the sender in this location, the head temp should read a maximum of 325 F on hot days. Cool days will always reflect lower head temps. Also, you will notice the highest temps at the slowest part of the course and lowest temps at the fastest part of the course regardless of engine rpm.

A few of us had the same problem, a little rework and good sealing fit it for me.

[Jay Jacobellis]

Thanks all for the info, I will go over all things said and try and fix this we are also at density alt above 7k' I think that makes some difference maybe a little timing or something . I am trying to get the bugs out so we have a better understanding of what to look for in this class. We are promoting this in the NASA rocky mountain region and will have 4 cars on the grid this weekend at High Plains Raceway. I have been talking to a lot of karters about this and they seem very interested so we need to find out what makes these things tic so we can help with the learning curve for anyone new. We hope to have 6 to 8 cars for the first spring race next year. Once again thanks for all the help. I'll have more questions as things heat up.

[Campbell Motorsport]

A couple more thoughts-

If you are frying your heads I am surprised your oil temperature is below 200. Generally if one is running extremely high- the other will also be high.

The scoops you have were probably marginal or OK for FV 1200. They will be too small for FST. You are feeding the top of stock VW cooling tins- but you are asking the air to turn 90 degrees twice before it enters the tins, plus there are no turning vanes inside the scoops. I suggest you contact Jim Nash at Mission Car- I think his scoops might help your situation. He does post on Apex.

Finally, while you need more air and need to work on the scoops- make sure there are no simple things with the engine that are causing it to run hot-- timing, jets.

Larry Campbell
Campbell Motorsport

[Jim Nash]

Here is a link to some information on the MRC scoops. See posts #38 and #40. It looks like these would fit your car alright.

Link--http://www.apexspeed.com/forums/showthread.php?t=55949

Jim

[Bill Bonow]

Finally, while you need more air and need to work on the scoops- make sure there are no simple things with the engine that are causing it to run hot-- timing, jets.

Bingo.

Jay, these are the two things that you had previously asked me about (timing and jetting) These things really need to be set on a dyno where things can be monitored.

[gbmetcalf]

Jay:
I would listen to both Larry and Jim. These two guys in my opinion make some of best looking and performing Formula firsts out there. Your scoops look similar to older protoform scoops. Jim Those scoops look awesome. Steve Dunlap's Wasp has some awesome looking scoops too.

G.

A couple more thoughts-

If you are frying your heads I am surprised your oil temperature is below 200. Generally if one is running extremely high- the other will also be high.

The scoops you have were probably marginal or OK for FV 1200. They will be too small for FST. You are feeding the top of stock VW cooling tins- but you are asking the air to turn 90 degrees twice before it enters the tins, plus there are no turning vanes inside the scoops. I suggest you contact Jim Nash at Mission Car- I think his scoops might help your situation. He does post on Apex.

Finally, while you need more air and need to work on the scoops- make sure there are no simple things with the engine that are causing it to run hot-- timing, jets.

Larry Campbell
Campbell Motorsport

Here is a link to some information on the MRC scoops. See posts #38 and #40. It looks like these would fit your car alright.

Link--http://www.apexspeed.com/forums/showthread.php?t=55949

Jim

[rgu]

Well first thing you should do is know what temps you are actually seeing. There have already been discussions right here about how this should be measured. If you are using a VDO style ring and picking up your temp reading under the #3 spark plug then you’ll have data like the rest of us. On a 90 degree day at a track with a long straightaway, fast and slow corners (Grattan comes to mind) you’ll see plenty of variation in numbers. It’s not odd to see 450-500 in a sequence of slow corners and 350 at the end of a straight.
Here is a pic of Phil McSherry’s Mysterian running Mission scoops. Yes they are out in clean air which is probably why they work so well. But they are thin and efficient and don’t seem to slow Phil up at all.

[Jay Jacobellis]

First off thanks to all that replied. I wanted to update you all on how things went last weekend. Hard to say if we corrected anything (due to the fact that the air temp never got above 65°) but we found out a lot. First session we did a yarn test and videoed it with the go pro. bad air flow around the head area and not much air flowing into the scoops(question, what lower tins are best for flow I have the type 3 or cool tins I believe, seems restrictive). My exhaust header and leading arms just screw the air flow big time. I think over the winter I will turn my header down and below the heads, also Jim I left you a message I need to talk to you about your scoops they look like they will do a better job than what I have. We ran well the only time the CHT warning light came on was on slow section of track and cool down lap(with these engines it should be heat up lap.) We had 3 kids out on track with FST cars and one FF. it was a great time my son finally got to mix it up with somebody, he was going at it with the FF.

[Jay Jacobellis]

Are these the best lower tins to use to get proper cooling

[rgu]

No.

They do nothing. I have a set and I'll give them to you for free but they just add weight.

[BLS]

I agree with rgu. However, there is a small flat plate that fits under the bottom, snapping in to the cylinder studs, that directs airflow to the sides of the cylinders that most feel is important.

[Hardingfv32]

I think you guys need to do a little homework if you think the tin in the photo is of no use.

Brian

[BLS]

I think you guys need to do a little homework if you think the tin in the photo is of no use.

We need a teacher...

[Bill Bonow]

I think you guys need to do a little homework if you think the tin in the photo is of no use.