But, but, but…  for the benefit of the people who are saying that right now, here below is what you want to point out.  This is the comparison when I used 100 octane fuel with the 605’s.  I’ve not had the F4H tuned for that octane and likely won’t.  Clearly as I stated before, there are other things that could be done to change the vehicles performance that could possibly alter the outcome dramatically.  What might the comparison be like if each were on 100 octane is a question that I will not be answering.

Conclusion

A point that needs to be considered when selecting a turbocharger, whether it is one of these two options, or something else, is that the vehicle operator has conditions, constraints, and preferences that all need to be weighed when deciding on the product to use.  Budgets vary dramatically, some people use the car at a track while others exclusively commute in town, and finding a suitable solution for one person does not mean the same solution will work for somebody else.  There is no easy answer to the question of what turbocharger system to select. 

After having driven my car with each of these turbochargers for an extended length of time in various situations I know I would be happy with either one.  For my current situation and preferences I’m glad to have the F4H on the car since the turbo is better suited to how I currently operate my car.  What would I think if I were using water/methanol injection?  How would I feel if I drove with 100 octane more often?  How about an E85 tune?  What if I built the motor, what then?  All of those questions have crossed my mind and the short answer is that I don’t know how I would decide then.

The charts in this report should give some idea of how these two options compare, but they can’t answer the question of how well the Franketurbo F4H or TiAL 605 would fulfill a particular owner’s unique set of requirements.

Evaluating the two under the best case conditions results in the following comparison of acceleration.  Not surprisingly the F4H produces significantly more torque at the lower rpm end, and the 605 more horsepower toward the upper rpm end.