Technical > Spud Miller's Cave

Exhaust temp questions

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Supercat:
Spud has been in contact with me on the base tune up for the car.
Being that this is a Buick that exceeds the normal flow for them, we are just playing it safe as we narrow down the tune. We make 2 passes before we make each adjustment and record the info.
Last week we ran 3 passes at 8.229-8.250 @ 167-168.1 with 1.21-1.23 60'
Going through the lights at 6400rpm
We will be changing to a 31" x13 tire trying to get the rpm up.

Again trying to learn the tuning variances used as ways to double check things.
Thanks everyone for the info.
I had ordered another box of plugs earlier today.

Cajuninjector:
We read egt's in each pipe and launch close to 1000 deg.
By the end of a quarter mile run they're about 1300.
We have the air bleeds  that install under each butterfly so it's easy to tweak the temps so they're all equal at launch.
 

JrFuel Hayden:
I have found when using my infared temp gun, the zoomie temps vary depending on the coatings on the pipes. I have had my pipes, chromed, VHT painted, High Temp ceramic coated, and even raw. I use the temp gun during warm-up to adjust the injectors to get them even temps. The EGT temps will vary depending on cam timing and yes tune-up. 1300° is too high for my combo, but some cams with more overlap can put too much fuel in the pipes and burn the alky in the pipes, so you can get higher EGT's. That's why it's hard to compare different racers EGT.
The best is to read your spark plugs, I use NGK because they are cad plated, and will burn off showing me how much heat I'm getting on the plugs/ in the motor. I have recommended to other racers that when they are working on their tune-up to install at least one new plug for each run so you can see what's going on. Example 1'st run of the day put a new plug in # 1 hole, 2'nd run new plug in # 2, etc. Just keep track of which cylinder has the new plug, I have a tool tray with S-plug holders, I just keep the run plug in the tray to remind me which has the new plug.

Have Fun,
Jon Hansen, Hayden Wheels 

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