Cooling efficiency and uniformity

[99mx5]

First of all, congrats on the website!

Tom, there have been some posts in other forums with concerns about hot spots and lean spots in the mixture when injecting post-blower. Have there been any findings in your testing that address these questions?

Where was the intake temperature sensor placed in the manifold?

Are there any clearance issues with the injector behind the tensioner bracket?

Is the Powercard used to compensate for the mixture and the main purpose of the 5th injector is to cool?


PS looks like emoticons are not working...

[Tom @ Fast Forward]

Thanks.

Justifiable concerns but the fifth injector on the 99-05 kits is just adding only a couple percent of fuel. As the A/F is already richer than 12:1, even if it all went to one cylinder, the others would still be at 12:1.

The tip of the sensor is about the middle of the blower towards the front.

There are no issues with the tensioner bracket.

Yep. The fifth injector is just there on the 99+ for cooling. On the 94-97 it is preblower and adds all the extra fuel. With 9:1 compression and 195/200 WHP the 94-97 was never a problem with the 5th injector. I think you will get better drivability on the 94-97 by leaving the stock injectors alone.

[99mx5]

Have you tried different injector positions on the blower spacer? Im just curious if the position of the injector can affect the efficiency of the cooling since the air travels at a 90 degree angle after the blower and placing the injector in the general path of the air as it exits the blower ehaust port.

[Tom @ Fast Forward]

I'm not sure how efficient the cooling can get but where it is, I can turn up the fuel and bring 13PSI boost back to ambient. I don't think there is a spot where it can do much better than that. Actually, I have found that cooling too much with liquid (water or fuel) is not a good thing. Once you exceed the dew point, it precipitates out and puddles doing no further good. I started with the premise that if a little is good, a lot must be better. Since then and 100 dynos later, I find that a little is good and a little is good. :) All you want to do with the liquid injection is take the peak off the heat to eliminate detonation and leave the rest of the fuel to either the stock injectors or an injector pre blower where it creates no cooling (actually adds heat) because it never gets to vaporize. What little that does vaporize pre-blower is cooling already cool incoming air and then simply becomes hot humid air.