If you have removed the front bumper support on your camaro, did it slow you down? I've lost about 2mph from where I was with the bumper support in the car. Could those two grill openings be taking in so much air that it is all getting caught under the hood of the car and holding it back? For example back 4 weeks ago it was HOT and the DA was over 2200ft I ran a 95.2mph 1/8 and then a 123.6mph 1/4 which is a gain of 28.4mph which is about what the car was averaging. Now, I've ran the car with 15 more RWHP (new cam) and 30lbs lighter raceweight at 800ft DA, it ran 97.4 mph in the 1/8th.. but only 123.09mph in the 1/4.. that's only a gain of 25.7mph.. .it's averaging over 2mph faster in the 1/8 but not gaining anything like it should over the last half of the track. What do you guys think?? I've built block off plates for all grill and foglight areas for this coming weekend and I'll try it out, but am I wasting my time and need to be looking somewhere else?

 

I haven't removed my supports or anything, but am definately interested in your results with the block off plates. Please keep us updated.

 

I wonder if your bumper is "cupping" at the top end and acting like a snow plow. I've had no problems wiht the bumper deforming (I think my ground effect helps stiffin it up) but I have heard of many people having this issue. If you don't want to take the time to do the block off plates just tape everything up with some 200mph tape and see if you see any results.

FWIW: My car has run it's fastest MPH with the hood off so I never really thought Aerodynamics played a huge part at around 125MPH.

 

I work with a guy that races oval track asphalt and he's the one that is having me try the block off plates and stuff. LOL, you guys are going to think this is crazy.. but today at lunch we took the car to the biggest down hill slope here.. about 2 miles long and when I'd crest the hill I'd pull the car into neutral at 60mph, it would never get over 70mph.. just like you were putting on the brakes and maintaining 70mph.. btw, we did his maxima the same way and we had to nail the brakes about half way down to keep it under 80 I'm going to do the same test tomorrow with everything blocked off.

btw, he said that anything involving speeds greater than 35mph can be affected by aerodynamics.

 

Actually that's a pretty good test that many people probrably wouldn't even think of doing. Let us know what you get for results tommorow.

 

interesting. keep us updated.

 

the rolling resistance is not going to be the same between the two cars. i don't profess to be an aerodynamic expert, but think about the differences between the two cars.

weight
tread width
rolling resistance between a 12 bolt and fwd
ever see which car is easier to push on level ground?
are you sure the owner of the "import" car wasn't giving it a bit of gas to say it's faster than your car

just offering some more thoughts. the test you did was not by any means scientific, as i'm sure you're very well aware of.

later,
Dave

 

I drove the maxima both times we logged the speed on it, but that doesn't matter anyways....... because..
The only thing I care about is the before and after of my car. We even used my GPS to log the MPH with. My speedo is about 2 mph off what the GPS was saying. I've installed the block off plates behind the grill tonight and we'll see what it does. I tried it again this afternoon on the way home from work and the car WILL NOT break 70mph coming down that damn mountain. If all the air coming in from the grill and other cowling I've removed isn't causing it, it has to be that my 12bolt is phucked up worse than I thought it was.... I did wear ear plugs on the 40 min. drive home today... God, I really really hate moser 1,500 miles on this rear and it is the loudest thing I have ever heard in my life.

 

i've had 2 Mosers and only one made a minimal amout of sound. lucky? i don't know. they've been doing rears for a long time and i'm not sure what all the hype is about that some mention about a rediculous amount of noise. i know another member on here who also has not ever complained about noise coming from it. sorry to hear it.

later,
Dave

 

I'm having it rebuilt friday with a new ring & pinion, along with new carrier, pinion, and axle bearings... so I'll report back if that cures my problem. Sucks to spend $500 on a $2,500 rear less than 4 months after you buy it new

 

I have removed the front support for weight reduction and considered aerodynamics in doing so. In fact, just by looking to at the whole thing even before testing or track time I fabricated a one piece smoked Plexiglas unit to block off the whole grill area since I run a FTRA unit. I did go faster, but this mod was done along with others so exact numbers for just the support and block off I don't have. I did consider producing this custom block off unit if there was enough interest. It's a little tricky to custom form and attach to the car while maintaining function and aesthetic. I can post photos later if anyone would like to see.

Also, on a rebuild, it depends on how tight or loose the rebuilder sets the gears up as to how loud the rear will become after break in. The tighter it is, which may be great for the track, the louder it will be which stinks on the street.

 

Yes !

Those big holes will pressurize the engine compartment tremendously.
This will cause aerodynamic drag and result in loss of MPH. Also by
removing the bumper is not good for the nose support. This will result
in the nose to sag, crack or even tear off. I've seen it happen. We
always re-support the nose with a light 4130 mini bumper to cure this.
Blocking the holes is a great idea like the last post stated.

Dave Kelsey
(KTS Race Cars)

 

Ive removed both bumper supports, but I guess the only one that affects aerodynamics is the front one. I dont drive the car that much, so Im not too worried about the facsia cracking, sagging, or tear off. However, if the front bumper support removal causes lag and hurts times/mph, then I'd sure like to fix it. So the 2 holes on the facsia, on each side of where the grill goes, are the holes that are causinig this problem? If so, then these are the holes that need to be covered? Has anyone actually proven by testing that the holes do indeed cause lag affecting mph and track times?

 

Ok, ran the "coast down" test again yesterday and averaged the speed gained over 4 runs. Before the block off plates it would consistantly gain from 60mph to exactly 70mph each time down the mountain. Yesterday, with the blockoff plates in place it would gain from 60mph to 73-74mph... the average of all 4 runs was a gain of 3.7mph (using the GPS, not the vehicle speedometer). So I'm totally convinced that it is very worthwhile to block off the grill openings and keep the black cowling that is below the front bumper support when you have removed the front bumper support.

Now, here's the second part of the testing I did yesterday. If you read at the first of the thread you'll see where my friends maxima with me driving it would reach 80+mph pretty quickly and I'd have to use the brakes to slow down. Well, I had my brother meet me at the "test site" yesterday with one of the guys he works with that has a 2001 6 speed SS with a stock rear in it. I coasted it down two times and both times it would reach 80+ really quickly and I'd have to brake. So there is something else that is seriously fucked with my car. I'm totally convinced that it is my piece of **** howling *** broke dick moser 12 bolt that's causing most of my problems with rolling resistance. I'm having it rebuilt this weekend and will try the testing again next week.

 

i have a 94 and removed the bumper support. after that i thought how am i going to keep the bumper from going in. i got som spray foam that is lite and dries hard. sprayed it under the front area and let it dry. 130to 132mph and no flex at the end. had people stand and video it. then i use my fog lamp holes and made a ram air kit that goes around to my mass air flow sensor. without ram air thru the filter best to date,.10.44 at 128. with ram air hooked up. 10.18 at 132 so i quess the ram air is doing it's job.

 

I've been luck with my rear, no noise, no problems? I've tried three different gear ratios. Bummer.

 

Ben, got any pics of your ram air?

Eric

 

no not yet. but i used 4 inch aluminum drier duct to fab the ram air. i'll tri and get some and send u.

 

gomer...check your pms

 

Aside from the drag it sounds like DFCO (deceleration fuel cut off)