Let’s talk Idle temps!!

Having a few issues with idle temps going into stage so would love to hear opinions/thoughts/ideas.

Chrysler wedge, 14/71 high helix blower with a set back. Idle temps are all over the place. Front cylinders are cold, middle cylinders are very hot. How much of a difference will changing the nozzles in the hat help?

All help is greatly appreciated.
Thanks, John

 

I generally don't worry too much about idle temps. What do they do when you go on laucnh RPM? If they come into line where you want them then don't worry yourself about it.

If not, work on getting the launch temps right and then see where your idle temps are and see if they make you confortable.

What's your head temp doing at idle? If it's holding steady or climbing real slow yuou should be in the ball park. Is this a new tuneup? What kind of history do you have with this combo?

You can try moving hat nozzles around but it will be trial and error and you may or may not have success. The temps you are seeing are most likely due to where you charge is exiting the blower at idle but it can't hurt a thing to experiment with this.

Troy

 

After messing with my temps for many days because my idle EGTs seemed high, the common advice I got from some of the VERY knowledgeable people on this forum was to set the BV at 80% and forget about it.

I noticed that if my BV got way rich my front cylinders would go way cold, spitting fuel, and my back cylinders would start going hot. I started leaning the BV until they came back together and guess what....it turned out to be 80%.

Although my EGTs never did come back down to what I thought they should be, the engine seems very happy at 80%, and doesn't have any problem with overheating during the burnout/stage process. I don't even think about idle anymore.

-Brian

 

i was taught that when you started reving the motor you wanted some fuel coming out the front two pipes guess what 80% to 82% im sure there are lots of people that know more than but some people just over think things exspecially when there starting out find a guy you can trust like mike c and there are many others i did the same thing until jimmy rector showed and told me some of the important things when i started and i seen him haul ass many times if he tells me something now i just do it

 

you don't HAVE to see fuel coming out the pipes. sometimes that depends on the tuner or tune up

 

Ya know those "VERY knowledgeable people" I mentioned? See the three posts above. They, and others, have helped me a ton since I got my car last fall.

-Brian

 

Hi Brian,
I think it is great that everyone is helping.....that is what this site is all about. Bruce has tuned some fast race cars. I agree with him. Fuel doesn't have to come out but depending on track conditions that may be the way to get down a slick track.

Pyro's don't always read the same as the next car. One point is if a cylinder starts out hot it normally doesn't recover. Tune ability comes in a lot of different fashions. Another indicator is to check the intake nuts, header bolts etc to see if they have loosened up. Detonation will rattle the nuts or bolts loose. So whether or not you have a high pyro reading and then loose fasterners in that area will tell you something. I have been fortunate to work with a couple great tuners along the way. I personally like to control the stage temps because you can have more control.

After awhile you will learn to listen to the race car and get a feel for what is right and when it doesn't like it. You can start to make changes along the way and make your car perform better and the way you want.
just my 2 cents worth

 

Wedge idle temps

We run a wedge motor, a little more mild than yours. 572", std 8-71 @ 28% over.

We dont have egt probes, just taking temps with a heat gun, we see the same thing, fronts are cold, the rest seem pretty hot, the back 2 being the hottest.

I stage with a little load on the motor and I think that helps balance them some, but I have never checked for sure.

I did drop nozzle size in my front two hat nozzles, seemed to help out a little but I dont think it was much at all.

Im fairly new at this myself but it seems to like the tune that it has now.

 

well bruce i know you dont have to see fuel coming out the pipes for one two run but i was saying from my experience most of the cars i have seen that run good when they start reving the motors i see a haze of fuel coming out the front pipes and bruce i have seen you haul ass many times as well and your imput would be good advice as well but did you give any are is all you stuff top secret (lol)

 

Hi all, thanks for the replies. We currently have a best of 6.70 (at only 190mph) and a top speed of 209mph, best 60 of 1.04 on a shut down pass. New to clutch deal. Tune up is very mild. BV is 78. The front cylinders get to a temp that we want while the middle cylinders stay hot during the run, yet the plug is showing no heat. Plugs are showing motor is way soft. We have had issues with exhaust valves though. Have not seen any signs of detonation. So, could the fuel be burning in the pipe and giving a higher reading? Maybe pooling like what Mike said? I don’t have the data here but if I can get it I will post that too.

Any more suggestions is greatly appreciated.

PS. Does anyone remember the Hyland family who ran a wedge in TA dragster during the mid 90’s I think? Pretty sure Tiffani drove and her dad (John?) tuned it.

 

Thanks Jim and Dale. I have been lucky enough to have some VERY smart people help me over the years so I am always willing to offer help and advice. . .BUT I will never give all my little tricks! . .

 

Thanks for the reply Mike. We have checked when the ports come in using the bottle method and they are not coming in during stage, so all good there. Will look at what we can do with the port jets. Would love to see some heat in the plugs too. Thanks again.