Stock intercooler vs VMP intercooler

It turns out that the exit temps from the Whipple are compression related. Not engine compression ratio but boost compression ratio. 14.5 lbs of boost is 2 BAR, and 29 lbs of boost is 3 BAR. Whenever you compress air, it behaves according to the combined gas law P1V1/T1 = P2V2/T2. The combined gas law says the pressure exerted by a gas is inversely proportional to the volume occupied by it. The pressure and volume of a gas are inversely proportional to each other as long as the temperature and the quantity of gas are kept constant. Here is a visual;



Both cylinders have the same weight of gas measured in grams. The cylinder on the right has twice the pressure applied to the disc above the gas. With zero leakage, the doubling of pressure reduces the gas volume by 1/2. It also proportionally increases the temperature. This is exactly what happens inside the intake manifold as the blower increases the pressure of the charge in the intake manifold. When we go from atmospheric (o psi) to 14.5 psi, we have gone from the one atmosphere pressure around all of us to 2 atmospheres of pressure or 2 BAR pressure. Increase another 14.5 psi to 29 psi, and we are at 3 BAR.

If the temperature of the gas in the cylinder was initially 85 ˚F (29.4 ˚C), remember we need to convert units, tripling the pressure to 3 BAR will triple the temp to 88.2 ˚C (29.4 ˚C x 3) which is 190 ˚F. This is absolutely inescapable.

If you run no intercooler, the charge temp in the intake port is 190 ˚F, period! Yes, the methanol can cool it. However, if you had an intercooler after the blower and before the intake port that could get the charge down to 100 ˚F (or less), that means that methanol's high latent heat of vaporization would chill the charge even cooler. This technique allows more charge into the cylinder to burn (remember the Gas Law) and at a lower temperature. What makes power? Air and fuel mass at the coolest temp possible to prevent detonation.

Going back to AJ for a moment, right after switching over to methanol and measuring intake manifold interior temps, the temps would drop significantly below freezing when you whacked the throttle because the methanol was further cooling an intake charge that had already been significantly cooled by the OEM IC using an ice water tank in the trunk. If you are after max power always, always run as cold an intercooler as you possibly can and then let the meth cool the whole shebang even further. You'll be glad you did. The air mass you will put in the cylinder will be substantially greater, the engine's power will be proportionally more, and your blower will work proportionally less.

Always run your intercooler, run the best one you can find, and run it as cold as absolutely possible.

Great points by both of you. I guess my upper 8s goal was one I set about 10 or so years ago before the blower efficiency of the G5 3.0 Whipple was even thought to be attainable. In place of E98 I may just keep it to a race grade E85. I had looked into the cable driven fuel pumps a while back but couldn’t get any real world info on how it would hold up on a somewhat daily driver. Since I have the MS3 Pro I was expecting to run a 2200 cc or the comparative Bosch 220 lbs injectors that Godstang is using. IIRC Ed you had me sold on the 2200 injectors (can’t remember the brand) that you recommend in one of Josh’s threads.
I’ll need to refer back to that thread to find the brand. Possibly The Injector Clinic?

Thank you both Ed and Steve and I hope this info is helping the OP as well. I in no way meant to hijack his thread. For the record I’m going to send the blower back for the race port and start budgeting for most likely VMP/CE intercooler combo.

Edit: I typed this up before seeing the last couple of posts by both of you. Ed FIC (Fuel Injector Clinic) may be the injectors I remember you being fond of.

I know this comment is going to draw a lot of discussion but I am going to throw it out anyway. On an internal combustion engine, the single factor most responsible for horsepower is manifold air density, with proper timing and fueling next in line. When you get your fuel map and timing map correct and optimize your intercooling to provide the lowest charge temperature (IAT2 temp) possible and the highest manifold air density, you will produce the best power numbers. Along the way, you might discover some data that may seem confounding. Just remember the gold standard for power is manifold air density, which comes with cold IAT2 intake charge temps.

Below is a link to a Gale Banks video where he produced more power on a compound supercharged engine by slowing down the blower and increasing manifold air density. Although the engine is a diesel, don't let that mislead you. The basic Otto cycle engine metrics for power production still apply. The essence of the problem, in the engine that Banks is testing in the video, is screw blowers expect to see near-ambient air conditions at their inlet. The turbos create pressures and temperatures significantly above ambient and the twin screw behaves in a counterintuitive manner.

In our applications, without a compound boost setup, the only metric that matters, and that we can control, is manifold air density. By using the Combined Gas Law in post #22 we can see how temperature affects air volume and mass in the intake manifold. Without proper cooling, the increased manifold pressure induced IAT2 temps will cheat us out of air mass. Once we begin to lose air mass (manifold air density) we begin to lose power. Slowing down the blower to put less heat into the intake charge can produce a power increase under these circumstances. The better approach is to leave the blower overdrive where it is and improve the charge cooling, ie intercooling for reduced IAT2 temps.

Here is the Banks video, watch how the power jumps in the last test even though Banks is still way off the power mark, by his own admission, but closer than the previous tests. Here is the video => 1200 HP Duramax. Although the Duramax produced more power in the final test, Banks explains the apparent conundrum. The answer is improved/increased charge cooling to get the Manifold Charge Density back by reducing, you guessed it, IAT2 temps. Although he hints at this, he holds that story for episode 14 which I could not find. 🙁

In the FWIW bucket at one point AJ decided to run w/o the intercooler because others had done so and encouraged him to also. The IAT2 temps got high enough to melt the IAT2 sensor and predictably, the car slowed down compared to its intercooler-equipped performance.

Sometimes a traditional IC is not present but the engine because of its configuration provides alternative charge cooling techniques. This is an example of an engine that uses a lot of methanol passing through a lot of injectors and provides for alternative charge cooling.


The fuel volume that passes through the 20 injector nozzles using the small pump is 4500 lph in round numbers. That kind of fuel delivery causes the blower and injector hat to ice up at the starting line and if you leave the line with the head temperature at 220 ˚F it is down around 190 ˚F at the end of the quarter mile. There is no cooling system, no water in the engine and there is no traditional intercooler. That massive volume of methanol, and it is a massive volume, is the entire source of the cooling effect.

When we get to two 2200 cc injectors on our engines, we are using a lot of methanol compared to any other fuel for an engine our size but that pales in comparison to something like the AA/A above. While the car does not have a dedicated intercooler, it has an intercooler in practice, because of the massive volume of methanol being injected at 140 psi or higher.

Depending on the fuel, how much is used, and how it is introduced into an engine it is possible to have a 'stealth' intercooler effect working for you. The how much metric and how it is introduced considerations tend to be pretty significant when considering the cooling effect.

ITSTOCK said:

I guess I'm not seeing the advantage for him in running meth. It's nasty stuff. I know the overall advantage of running m1/m5, but it doesn't seem like his setup warrants it in comparison to other combos, especially when he is already off the throttle and still needs to run the intercooler. They aren't that extreme of combos, and with the numbers, he is putting down, he is nowhere near running at the ragged edge.

Click to expand...

There are multiple good reasons to use methanol instead of gas for racing, rules permitting, Steve. Probably one of the first on most people's lists is cost. A 54-gallon drum of C16 on the VP site today has an MSRP of $1,243, freight and tax not included. A 55-gallon drum of commercial grade Methanol at current Methanex North American pricing is $1.73/gallon today or less than $100 in 55-gallon drums, again freight and tax not included — and you have something better than a high-end racing gas for fuel. If you buy from a local industrial distributor, you can avoid the bulk of the freight cost and possibly get the per-gallon price reduced a bit also.

Then, of course, the relatively high octane rating (110+) does wonders for detonation suppression, and of course, the exceptionally clean burning methanol provides easily readable sparkplug surfaces. The low heat imparted to all engine components; the ability to run very high compression ratios, even with a blower; the unusually low exhaust temperatures, and the relative (not total) indifference to fuel temperature all add to the fuel's attractiveness. There are more 'good things' attributable to methanol, but this is a pretty good start and certainly, enough to argue for methanol over race gas, again, rules permitting.

In fairness, you should use stainless fuel system plumbing wherever practical and certainly methanol-safe injectors. Ancillary fuel system damage can be mitigated by emptying your tank at the end of the race weekend, putting some gas in the tank, and restarting your engine on a gas tune to drive it into the trailer.

The methanol replacement with gas should be done even if you have a methanol-safe fuel system. Both alcohols are hygroscopic and will absorb considerable moisture directly from the ambient air. Water will change the way the alcohols burn and also the power available from them. With today's EFI systems draining the tank and refilling it with gas is not as big a deal as it was in years gone by.

Once you begin using methanol, you will be very reluctant to return to gasoline as a race fuel.

ITSTOCK said:

On another note and back to injector sizing, a reason why I chose the 1650s, to begin with, was that they are very good at avoiding corrosion, whereas when you step up to all of the 2000ish CC injectors, their bodies don't fair well to E85, and especially not meth.

Click to expand...

The larger dual 2200+ cc injectors that AJ is using are, I believe, four years old, possibly more. Their bodies show no signs of deterioration. I have another friend with a ProMod that used large electronic and mechanical injectors simultaneously without any indications of damage to the body of the electronic injectors or other components.

While I am sure the units you saw experienced it, I suspect that the damage you observed may have been initiated by something other than the fuel. There are enough good experiences with methanol that I suspect something else was at work in the instance(s) you may have observed, Steve. In fairness, significantly, both of my examples used methanol and not E85, although I would not expect a difference.

Your engine's appetite for fuel places you very near the top of the delivery window for the 1650cc units. Larger or multiple injectors to get the duty cycle down below 70% would benefit your engine program — especially for night racing or should you decide to turn up the boost.

Methanol is not a street fuel. It is a race track only fuel. If you want 90%+ of the methanol benefits on the street, then pump grade E85 would be the obvious choice.

Like methanol, ethanol (E85) is hygroscopic. However, as long as the fuel tank is regularly refilled, the water content will be low. Running a flex fuel sensor will tell the ECU the actual ethanol content, irrespective of water content, and allow the ECU to make proper fueling decisions in day-to-day driving.

Another mitigating factor for E85 is mileage. E85 does not get good mileage. Normally this would be a negative. However, ethanol's affinity for water makes this otherwise unpleasant mileage issue a positive because you won't have unused 'old' fuel in your tank looking for or having already acquired airborne humidity.

Hey guys, if you can, you should attempt to size your injectors for a duty cycle between 50 and 60%. In the 'old days, when large injectors were not available or only available as high-priced alternatives to our long-standing 60lb Siemans goto injectors, it was common to run duty cycles upwards of 85% and higher. Today that is no longer necessary, just like it is no longer necessary to run elevated base fuel pressures to squeeze out that last drop of fuel.

When you run high % duty cycles, you run the injectors at the upper limit of their acceptable temperature range because they are essentially "on" all the time. Dropping the duty cycle into the mid-50 % range allows injectors to run considerably cooler. In addition, the idle fueling (low delivery curve slope) atomization is much more predictable and reproducible on new injectors today, so idle is no longer an issue with the newer 'big' injectors. Another attractive attribute is the newer large injectors give you significant headroom for increased fuel demand/supply down the road.

Don't paint yourself into corners you don't need to be in.