We started out to do an AWD vs. RWD comparison, but as it turned out, after a few pulls, we realized my front dif was, and likely has always been, toast. How did we know? We made 3 pulls back to back, removed the drive shaft and made 3 more pulls making sure to duplicate all conditions. The difference between the runs was less than 5 horsepower!!! Kind of explains why I always got stuck in 3 inches of snow last year? Anyway, I always wanted to do a race gas tune, so, we took this opportunity, as the AWD test was spoiled. Since we had removed the drive shaft, we base lined the car on pump gas and meth and RWD. Then we drained all the pump gas and the (100%) meth tank and tuned with MS109 and 50/50 meth/water. (As a side note and from experience, we felt that race gas with 100% meth would greatly impact performance such as spool, so we went with 50/50 as we can’t disable the Aquamist system unless you want to run on waste gate, and I don’t.) We learned that we cannot run pump gas on my race tune, however, my pump gas-100% meth tune is only 20whp and 20wftlbs shy of my MS109 -50/50 tune. This is the case because I cannot get over 1.3-1.35 bar. My waste gates are maxxed out and my boost solenoid duty cycle is at 100%, if not higher. Obviously, we could achieve much better power numbers on race gas with more boost, we just can’t get there, with the parts we have. We could NOT get it to pull timing on the race tune. We kept adding timing, but made no more power. (Yes, we took the timing back out) It did pull 1-2 degrees on the pump tune. We feel that by adding a couple gallons of MS109 with the pump gas would likely get us to the race gas level of power as the timing retard was likely worth the 20hp gain. As of an hour ago, my car is officially RWD for now...

 

How much difference were you expecting in power between RWD and AWD?

 

Nice, I guess you are going to keep the pump/meth tune as your main tune then? Thanks for the data. This "meth business" sure is interesting. Prolly my next mod.

 

I expected to see a 25-30whp gain at least going to RWD? Not a HUGE revelation, but our AWD is a hugely overrated...

 

For all intents and purposes, I have no race gas tune...I plan to run my pump gas/meth tune exclusively, and give it a sip of MS109 when I know I am going to "compete". A very small insurance policy...

 

Good write up Mike and interesting facts. Sorry to hear about the front diff but glad to see you are in RWD mode. I will never go back to AWD

 

You really have made the most of your car. Impressive Mike. Can't wait to show you real speed in October. I keed I keed...

 

Mine still worked and wouldn't spin the rollers on a (dyno, dynamics) dyno at all. I don't think enough power is being sent to the front to rob much power. Would be nice to know for sure though, I may try it in the near future, but I don't think anyone would get that much rwhp loss. Most of the difference in speed comes from drag and weight.

 

We still plan to do it, I just need to get a good Dif. Officially taking donations. If I didn't see that much of an increase, I would NOT have been disappointed. We just know that MY car had a 19% DL loss and most RWD cars are in the 12-15% range. I was just doing napkin math...

 

Thanks Art and Thanks Todd. I'm just bummed I found this out now. All those trips to the track and all those 60-130's, all done with all that dead weight and parasitic drag...

 

So it's 20whp difference between race-meth vs pump-meth on 1.3 - 1.35 bar and can we say the gap between them should be increased when you crank the boost level up?

For example should the difference be something like 40whp when you run 1,5 - 1,6 bar?

 

Probably, but he can't "crank up" the boost. He's stuck at 1.35 bar..

 

ON MY CAR, WITH MY MODS, it's a 20whp difference, yes. I personally don't think the 18G is very efficient over 1.4-1.5 bar, based on what I have seen on MY car at 1.2-1.3 bar, unless you have bigger intercoolers. My Meth kit is awesome and has very noticable gains and provides a level of consistancy I have not seen yet on other cars.

 

Interesting findings Mike...
Sorry about the disappointing hp number for RWD. At least you can loose the 71 lbs and maybe a little drag.

 

Good stuff Mike! So what were the final numbers?

AWD is for monster trucks anyway....