Stock ATS-V and CTS V-Sport fuel system consists of a low pressure electrical pump in the fuel tank, and a high pressure mechanical pump on the driver’s side exhaust cam. The stock fuel systems are already starting to have difficulty keeping up by 17 pounds of boost and 500 whp. This problem occurs when boost is brought in quickly and torque starts to peak. It is also exacerbated in the overdrive gears, and engines have been lost for this reason. We see the high pressure drop off on every ATS-V we tune, as soon as boost is increased. The more boost we add, the worse the problem gets.
Here are some estimated performance capability numbers using Tapout fuel system solutions. The fuel system components themselves won’t produce this much power. These are just estimates of what each fuel system upgrade should be able to support safely.
- 500 whp (gasoline) stock LPFP and stock HPFP
- 600 whp (gasoline) Tapout Fuel Cam
The Tapout LPFP can be added to any of the above to provide a little extra padding or safety margin.
This is a factory GM ACDelco camshaft with modified HPFP lobe. We have reground the fuel lobe to have 6.35mm lift instead the stock 5.25mm. This is the maximum possible within the hardened depth area of the stock camshaft. At 6.35mm this results in 21% more HPFP volume capacity compared to stock cam. No custom ECM tuning is required for this fuel cam by itself.
Check out this screen shot, which shows our fuel system easily maintaining 3,200 psi from 22 to 24 psi of boost through 158 mph on full E85.
Fuel cam adds stroke to HPFP, and HPFP internals add bore. When used in conjunction, they provide ~ 65% more high pressure side fuel volume.
We recommend using a timing chain retention tool (part number EN-48313) to hold the timing chain in place during your camshaft swap. This tool is readily available online for approximately $200.
Custom tunes and any performance parts that could affect vehicle emissions are intended for off-road use only and not to be installed on any vehicle that will be operated on any public roadway. Not for sale or use in California.
What fuel system mods are required to run E85?
it depends on how much boost you are targeting and how high of ethanol content you would like to run.
Some people claim that you can run E30 on the stock fuel system. However, this is a dangerous and misleading statement. We have repaired and/or replaced many engines for people who trusted that negligent advice.
Although the stock fuel system can technically handle E30, you will be required to reduce boost down to the point that you won’t make any more power than you could have on pump gas. With our Stage 1 LPFP, fuel cam and alcohol content sensor you can typically run ~ E47 without issue. This is convenient mix of half pump gas and half pump E85.
If you add on the AutoTech HPFP internals, you can run up to straight E85 at reasonable boost levels. With the stock or Turbobay turbos turned all the way up on a Kill Tune, you should be safe somewhere in the E60 to E70 range.
For those stepping up to Caddy Issues turbos, you will need to upgrade to the Stage 2 OG Solutions LPFP, and/or add methanol injection.