Changed the title from "Can I fit a D15B7 TB on a ITR B18C" to "best way to Detune a B18C ITR motor"

Trying to slow the car down to fit a different Roadrace class. (we use a time index for car classes). Already swapped in a set of B17A1 Cams, and I was going to use a B18B or a B17A1 throttle body.
Car weights 2400LBS in race trim. (1/2 tank of fuel) So we will fill it now but Dont want to add too much weight as that will increase tire and brake wear.
Stock ITR ECU, Stock motor, 4.7FD trans.

Trying to take about 1.5 secs out of the car on a 1.7 Mile road course thats a low speed track.

 

No..they don't fit. There are other ways to slow you down other than choking the engine

 

What would you suggest?
Only thing done so far is the B17A1 cams, Its a stock ITR ECU. Not really interested in putting weight into the car, outside of running a full tank of fuel instead of half for races. Car is at 2400LBS and more weight will just equal more tire and brake wear.

 

HOnestly, check your rules and see what's allowed by way of power reductions. In some cases, what most do is they sell they're current setup to get a d-series engine again, to GUARANTEE that they'll make less power in that class. If you can't let your foot off of the accelerator and sandbag enough to stay within class limits, anything else you do is either not going to fit, or doesn't make sense to try.

Other simple methods are simply to put an air restrictor on your intake so that the size is smaller (allowing more torque, but less power) Similar to this used on turbocharged vehicles to stay in a particular power class



This is really the worse section to try and find answers to reduce the capability of these engines. Especially trying to cross-reference parts. You may need to talk to your fellow racers in that class to find out what they do in that situation, as almost no one here would want to understand that principle (yes, I know, but they like to race) in order to stay within a specific road racing class.

Best of luck to you.

 

What about a throttle body restrictor plate ??? Many SCCA and NASA classes require a specific throttle body inlet size. A thin steel or aluminum plate matching the gasket with a smaller opening in the middle is the most common.

 

Exactly. One may need to be made, but that's more of what I was referring to.