Enduro Starting Problem

[Andycostin]

Has anyone really pinpointed a single reason that they have trouble restarting their car after the first half of each enduro? My understanding is that it is a combination of both engine soak (no/low coolant flow through engine) and soak of intake air (due to no airflow in intake whilst sitting still), and the associated incorrect temperature compensations in ECU's.
I guess it may also be Vaporisation in the fuel lines, but I feel that the first two are more applicable.

[Andycostin]

Has anyone really pinpointed a single reason that they have trouble restarting their car after the first half of each enduro? My understanding is that it is a combination of both engine soak (no/low coolant flow through engine) and soak of intake air (due to no airflow in intake whilst sitting still), and the associated incorrect temperature compensations in ECU's.
I guess it may also be Vaporisation in the fuel lines, but I feel that the first two are more applicable.

[Frank]

seems quite a few have lack of electrical energy

im wondering if some run the fuel rail as a "dead end" and get vapourisation in the fuel rail

and it seems many just have poorly tuned engine

[B Lewis @ PE Engine Management]

Based on what I've seen in the past, there are two main reasons for hard starting and both have already been mentioned:

1) Not enough fuel to restart - I think that many teams do not have sufficient seat time prior to the race to practice "hot" starts. As a result, there is too little or no starting compensation when the engine is hot. This is compounded by the fact that the engine is allowed to heat soak during the driver exchange. With no air/coolant flow while the engine is sitting still, sensors tend to take on the temperature of the component they are mounted in giving false readings of air and water. Bottom line is to make sure that you tune your engine under all of the conditions that you expect it to perform under, including hot start.

2) Improper or insufficient electrical system - This usually includes things like poor connections or undersized components like battery or wiring. Undersized wire seems to be a very common problem in the starter circuit. Before wiring that part of the car, be sure to reference the wire gage used by the OEM. The starter can easily draw as much as 30 amps when cranking. Also, it is very important to use some sort of a starter solenoid. Running long lengths of wire from the battery to a switch and back to the starter can introduce allot of resistance in the circuit. I have seen cranking speeds increased by as much as 200 RPM by installing a solenoid on a racing 600cc engine.

[Erich Ohlde]

At the 04 Endurance, we had one of the quicker driver changes (I think) and we didn't have a problem starting our motor back up. We were running a 12 A/hr PowerSonic POS battery. Although our first driver was slower than my grandma (he didn't push the car anywhere close to its limits)

Erich Ohlde
KU FSAE
Jayhawk Motorsports