Just wondering if it would be worth considering running Meth only to lower IAT and not running an intercooler. For a drag racing perspective only, obviously not practical on the street where you may come into boost and run out of meth, and Just on low boost applications, about 7psi for an LS7.
Any of you guys out there already done this?

Tune it to Kick meth in when boost comes on, can check and top up reservoir after each pass.

Would save some weight by not having intercooler.

 

I don't think the intercooler does much on my F-1 at all on street. I'm getting my plumbing togethger to remove my IC and see if it makes a diff. Before i installed meth i could not go wot without major high IAT's so the IC can not handle my F-1. Now with meth i went from 180's 190's to 80ish all day long. If your talking about 1/4 mile runs and using meth i believe you don't need IC. I think if you would road race in IC would be more apporpiate.
I have the A&A IC.

 

http://forums.corvetteforum.com/c6-t...lications.html

BJK

 

Helga203, let me know how you get on once the intercooler is removed, in theory it should be fine.... lets hope hey.

07MontRedcp, thanks for the link, very informative.

Anyone actually ran a centri with no I/C on an Ls7, with or without Meth?

 

With the A&A supercharger on my car, driving it on the street and freeway, I'm almost always below 2000 rpm. At 70 mph, I cruise at 1700 rpm. In this driving mode, I sometimes get up to 2500 rpm before a gear change when on the throttle a little bit. At these rpm ranges, the centrifugal blower just isn't doing much/nothing and the bypass valve is almost always open. At the 2500 rpm and up rpm levels I start to sense the supercharger. At these low rpms, I doubt that the supercharger output air temps are elevated. So for the driving mode described here, I think you could drive without an intercooler. However, once you get into the 3000/4000 rpm range and up, I'd imagine the compressed air temp starts to soar. IS THERE A THERMODYNAMIST i

The A&A intercooler is impressive. It completely encompasses the under bumper grill area. The intercooler is surrounded by shrouds, top and bottom and on the sides, Any air entering the front grill opening must flow through the intercooler. The intercooler is all aluminum and I don't think it weighs that much, although it's not flimsy. The bottom of the intercooler, where the hot compressed air enters, is an aluminum casting about 3/16 inch thick. (The casting is externally polished). Cooled air exits the intercooler on the top. It doesn't weigh that much so I don't think there should be a weight issue with installing it. I think you do have to remove the front fascia (fancy word for that plastic thing we used to call the bumper). I imagine for someone who has never removed this thing, it might be a little fussy.

I'd hate to think what kind of import duties you're paying. I lived for a total of 9 years in Australia, intermittently from 1975 to 1992. Really loved living there. Adelaide, SA, my last couple of years were in the Adelaide suburb of Glenelg. The climate in Adelaide is very much like the climate here in the South Bay of Los Angeles. I think Adelaide could have a couple of weeks or so of warmer weather in the summer than here. Like a lot of houses in Adelaide, the houses here don't have air con. It's pretty much cool all year around, and on the occasional warm days, a cool ocean breeze starts to flow in at about 10:00 PM if no earlier, so you avoid AC.

 

Most people with LS7 (assuming stock) usually buy kits that are complete, including IC. The issue that’s hard to get around is temperature rise, which is 11-15 degrees F per PSI of boost (efficiency dependent - supercharger). So with your 7 PSI target it wouldn’t be unreasonable to expect 85+ degree rise over ambient… The LS7 being high compression total timing would have to be very conservative.

Meth – yes it works as many here know. But with no IC the quantities required to affect a meaningful temperature drop would make your tune 100% meth dependent. So any hiccup w/system, you probably couldn’t get out of throttle fast enough. Most systems are based on Surflo pumps and similar… these pumps where originally designed for agricultural purposes (yes upgraded wetted surface, but still a diaphragm pump). The reliability doesn’t come anywhere near OEM, so that would be biggest concern, followed by repeatability (this is because you are 100% meth dependent).

The IC I’d say adds 50+ pounds when it’s all said and done, not the lightest, but pretty damn reliable… If you want to drag race most of the time then why not water to water heat exchanger (IC), fill up reservoir with ice. Then if you want meth for safety (octane boost and temperature drop), at your boost level (7 PSI) you could get under ambient temperatures – food for thought.

 

Thanks guys,

Skunkworks, yeah i know it would be 100% meth dependent, that is my concern and reason for asking if anyone has already done it, in order to find out how reliable their setup was. What there IAT readings were and how much they got lowered, etc.
Meth works great and is a light setup, but not sure on reliability when 100% dependent on it with no safety net.

 

Two things happen. One is the amount used increases since the system has to work harder to control temps. 2.. This leads to simply being more vigilant with the meth system.

The more dependant you are on the system to do its job, the more you have to be making sure things are working like they should. Guys running 8's on meth are more vigilant that guys running 11's. But most parts of the car get more attention as the power increases.

11DF per psi. so 7 PSi is 77 plus 90 outside is 167. That can be brought down to the 130's.. you could technically get away with 167 for an IAT reading. And simply run higher timing in the 140 or below range. vs 90 degree IAT with an IC and meth.

 

Julio,

Thanks mate.
Will be running 98octane also, so this may work if i get it right, gonna be expensive if i don't. LOL

 

It works, but you will need a LOT of meth. You are eating up

1104KJ of energy for every KG of methanol you evaporate. If you look at the mass airflow of your supercharger system, multiply that by the heat capacity of air (about 1J/G/degree K) and then look at your airflow, you can figure out how much methanol you need to spray to reach your target IATs...
Worked example:

Paxton Novi 1500: 1200CFM * 0.08lbs/cubic foot = 96lbs/min = 43.5kg of air per minute.
At 7PSI your discharge temperature will be in the 70-80C range; to drop it back down to, say, room temp (25C) your Delta T is 55 degrees.
43.5kg of air * 55 degrees * 1kJ/kg/degree = 2 392.5KJ.
You would need to spray about two kilos of Methanol per minute.
Thats 264lbs/hr
The typical injector we run on an FI 'vette is 60lbs/hr and that number translates into 33lbs/hr per cylinder, so you can see how you'd almost be better off just running the car on pure methanol

For comparative purposes most methanol setups I have seen (the one on my car is a typical example) are injecting about 10% of the fuel charge as Methanol, not 50%.

 

Nice maths there PowerLabs!

 

PowerLabs,

Ultimate respect to you mate, thanks for your time and knowledge. I just been playing with the numbers also, and as you said it is do-able but probably better off running on methanol alone.
cheers

 

Technically if you start spraying a small amount and get a small drop. A lot of the time the added octane from what your spraying will be fine to support higher timing.

Power gains are negligible below a certain temperature threshold. Typically 130-140 DF would be great to have temp at. Below that its a minute amount of benefit. Most would say if you keeps temps under 150-160 that would be ok as well. And using methanol for cooling should be able to get this figure pretty easy and not have "that much" needed to be sprayed.

HTH

Julio

 

Not sure I buy the temperature argument… Convert to absolute (degrees Rankine) 459 + temperature in degrees F. So (459 + 90)/(459+160) is 0.88 or 88% as dense as air at 160 degrees vs 90. That seems like your leaving more than a little on the table.