IndyCar Series drivers came out of the Daytona Open Test raving about the work done by Honda during the offseason.
Two major changes were made to the Honda HI7R Indy V-8 engine for the 2007 IndyCar Series season – an increase in engine displacement to 3.5 liters and a shift from a fuel blended from primarily methanol (with 10 percent ethanol added) to 100 percent fuel-grade ethanol, a renewable energy source.
The results from Daytona show improved reliability and add to the level of competition while keeping the performance level and costs the same.
Roger Griffiths, race team technical leader for Honda Performance Development, discussed the changes and their effect on the engine program following the test.
Q: Why the increase to a 3.5-liter engine, and how did you make the change?
Roger Griffiths : With the addition of more road course events on the IndyCar Series calendar, we felt it was important to improve the torque response of the Honda Indy V-8, and increase the width of the usable power band.
This makes the engine less “peaky†and better suited to road racing. It also means the engine will be less stressed, which is good for reliability and helps us reduce costs to the teams as well.
Increasing the displacement to 3.5 liters was relatively simple to accomplish by changing the crankshaft and connecting rods. All other major components are the same as in the previous 3.0-liter engine.
There also are some minor revisions to the intake system to achieve the targeted performance levels, reduce costs, and simplify the engine building process. The last two are key components in the plan to once again reduce the overall program costs to the teams.
Q: What additional changes were needed to accept 100 percent fuel-grade ethanol?
Roger Griffiths : The most important aspect to the fuel change is making sure that all components in the engine that come into contact with the fuel are “ethanol compatible. †This includes the fuel injectors, fuel lines and seals. The Engine Control Unit [ECU] settings also have been adjusted to meet the “burn†requirements of ethanol. Fuel mileage also has improved, to the point that the 2007 fuel cells have been reduced in size to 22 gallons.
Q: Based on the mix of street/road course and various-sized ovals, what are your thoughts/projections for ’07 regarding a less-costly engine program for teams but one they can have confidence in?
Roger Griffiths : With the increased engine life, teams may well get an additional event out of an engine build, and that helps further reduce costs. Engines that ran two races between rebuilds should now last for at least three events.
Despite the fact that our cost targets are significantly lower for 2007, we’ve been able to maintain Honda’s high quality assurance procedures. We have very thorough mileage tracking and development testing procedures that will remain for 2007 and beyond.
In fact, in durability testing of the engine, we regularly run far in excess of the track mileage limit and under tougher running conditions, so that we go into the races with a high degree of confidence about the reliability and performance of the Honda Indy V-8. We’re looking forward to another great season this year.
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