Originally Posted by resdoggie

The dented headers did increase power. They 'proved' it! Oh wait, maybe the dyno wasn't calibrated correctly?? Maybe the gains were insignificant? They seemed to be elated that there were gains! Maybe the dyno wasn't calibrated correctly for clutch fan HP loss? The point is, they do dyno tests and show results. So we should all dent our headers and switch to electric fans? Of course not.
You can't blow warm air through a 2-1/2" thick radiator and expect ALL the heat of the coolant will be transferred to the air. Not in a distance of 2-1/2". As for the evaporator which is below freezing, the air passing though into the cabin will only be 45*F-55*F or thereabouts but not below freezing. There is just not enough time for the air to heat or cool to the surface temperature of the rad or evaporator, respectively. The 2nd Law of thermodynamics, right? Btw, I'm enjoying the discussion.

Originally Posted by augiedoggy

sigh.. I never said all of the heat I only implied enough to raise it 20-30 degrees.. This is why temps for an automotive ac unit at the vent where there is some loss/warmup vs right at the evap unit is normally between 35 and 45 degrees (not 45-55F btw)
and no I never implied everyone should switch to modern electric fans.. Only those wishing to do so to improve their cars cooling capability.. As far as denting your headers? Knock yourself out. I got something out of it myself as I did have to dent one of my collectors to clear the steering box and I was told it would hurt the cars performance.. The point of the experiment was to prove the results and in this case that the dents likely wont be detrimental to the headers performance afterall. it doesnt matter how well the dyno was calibrated all the tests were consistently run on the same dyno which still show a positive or negative vs non dented. Just like the oem clutch fans showed a 28-30hp loss at 5200rpm vs an electric fan setup.. You can choose to ignore it and even state the opposite but it doesnt mean others wont point it out and defend their point of view based on such actual data. Theres lots of reasons stock may be better for some and electric for others but it doesnt change the pros and cons of each. same with any choice such as an air cleaner. The only point I was concurring on was the dual snorkel stock cleaner doesnt HURT performance on your average performance built 350 or even 383. It can even have the benefit the engineers designed it for.

Originally Posted by Flyboy1958

As stated,......no real data, so everything is pretty much just a wag. And even with data, it would only apply to that single one car.

Correct...i can answer a few of these items that are niversal I assume ..noting i am completely opposite of stripped l82 manual originalish And of course how far from equator

My underhood is very simple, and clean. No airconditioning, no power steering, no power brake booster, no EPA gargabe.....so I would say, based on my common sense, that there is less restriction to any airflow. I have an open filter element. NOTHING under MY hood gets very hot, certainly not hot to the point of melting anything. Exception.....I would not tounch the uncoated stainless headers with my bare hands. And I carefully route plug wires, electrical wires, and hoses to prevent any direct contact with hot metal. I believe claims of any recognizable HP or Torque from Cold Air Induction is limited to extreme high rpms and race conditions.

In fact the 79 cold air is only applicable at wot...gm claimed it did increase hp and obviously double square inches of opening..

ON the street.....its a joke. How about this:


- How much HP is lost with additional electrical load on alternator with electric fans. It is estimated 1-3 hp bit my chinesium rock auto replacement alternator dropped rpm big time with 30 amp rear defogger triple what my oem rebuilt did so i think its more and ymmv
- How much HP does an airconditioning compressor take? People seem to need their AC. Is it noticeable when the compressor kicks on? YES drops about 200 rpm and noticeable driving
- How much HP does the power steering pump take? People today can't even drive a manual steering car. No clue but love it and lubricates thefloor of my garage periodically
- How much HP does the silly air pump take? Never had one but heard maybe 3/4 hp
- What is combined HP of AC AND Power steering AND Air Pump take.....do you think you notice ANY diffference in acceleration with or without this stuff? No. Yes see above ac to nly no clue pump and ps
- How much HP does the wife sitting in the passenger seat take? My wife is 140 lbs.....and I notice nothing different in any way when she or anyone else is in the car. My 200 lb friend took a ride with me the other day.....nothing different.
wife no..240 pound son yes
- Does the car go faster when the gas tank is near empty? Full or close to empty.....no difference. Yes noticeable acceleration and handling 24 gallons vs 5
- How about with a 200 lb passenger AND a full tank.....notice any difference? No. Yes
- How about running WITHOUT any air cleaner....i.e., no filter restrictions......do you notice any difference. No. NA
- Guys have stripped their cars down to almost nothing, to save 500 lbs.....and I bet you barely notice the difference.NA but imagine yes
- As for cold air induction.....does the car really go noticeably faster on a 50 degree day than a 90 degree day......? On the street.......can you really actually feel the car going faster between stop lights? Not talking about drag strip times. no because my car temperature isregulated ~130f for best af ratio unless wot which opens to ambient
- How about air density......notice the difference from one day to next? See above yes at WOT

All these attempts to improve performance WOULD apply if you are running at full RPM on a race track. The guy with all the restrictions and HP losses MIGHT not win the race against the guy who doesn't. On the street, driving from ZERO to 60, I bet you could run an experiment and would find out all this stuff is totally irrelevant. I actually HAVE run that experiment by slowly changing my car, making some of these "improvements", from when I bought it in 2010 as a stock L48, to now. Is it better....a little, not much. The most significant and noticeable difference was the 406 SBC.....over the original L48. The rest of it.....not so much. But truthfully, the stock L48 could get the car to 90 mph......faster than I ever need to go. The 406 just does it quicker......and yeah, it fun to accelerate. As for speed....EVERY car today on the street can do 90 mph, quietly, easily, and comfortably.

People, including me, do all this stuff because they THINK it will make a difference, and because its part of the hobby.....but I for one have come to find out almost all of it is just BS. I have commented on some other threads about my special new modern tires, same BS. If anything, these improvements are very very minor, and can be offset by equally burdensome things like AC, power steering, fat people in car.....etc. Its all okay.....but lets be real.You nailed it hobby and fun though and i need to compensate for all the things that drag down my motor like the items listed..agree lots of it high hanging fruit for some not all applications..

And the biggest joke of all, from what I notice.....people put all this time and energy and money to make a car go faster......and then drive it maybe 400 miles a year. Most of the time driving from the house to a parking lot car show, where they sit around in lawn chairs talking about their big HP improvements. Very funny.

Originally Posted by interpon

I’m about 3-4000 city little highway with 3.70 gears..

i want all that power too when i want...and then get some milk late at night quiet in my neighborhood ..i want it all! And man its cool to see everyone’s stuff ideas and great skills from automotive lore and experience...

You should run a few thermocouples around in mixed driving..it would be cool to add your datapoint...!

Originally Posted by REELAV8R

Those of us who have converted from stock fan assembly to electric fans KNOW the difference. Those that have not, do not.

Originally Posted by REELAV8R

Flyboy?...you know anything about density altitude?

Originally Posted by resdoggie

Yeah, 4 posts in a row sounds like a rant to me. So, what tires do I need to avoid?

Originally Posted by Flyboy1958

Yes. and I know where you are going with that comment. Lift, turbine engine performance, piston engine performance are ALL effected by density altitude. But suggesting it is relative to driving a car on the streets at 0-60 mph, and that it is recognizable in the seat of your pants......I don't think so. In an aircraft operating from sea level to 45,000 feet, with temperatures ranging from 90 degree F to -50 degrees at altitude.....yeah, difference. From an engineering only standpoint.....you would be correct......there is a difference in the car. In a race, or in a race car,.....it could be the difference in winning or losing. Not on the public streets in driving for pleasure at responsible and legal speed. THAT is my point.

Originally Posted by REELAV8R

these cars are carbureted, not fuel injected. Piston engines of course,lol. A carb can only be tuned to operate ideally at one point in time ie one density altitude since we have no mixture control for these. The carb can compensate slightly but not for massive density altitude swings.
thing is the carb is tuned with the hood up in a garage at say 80* f.
then you close the hood and go drive. Is it still 80* air being injested by the carb now? If it’s not then it’s no longer in tune.
consider the LOCAL environment of the engine and the air it’s being forced to injest.
THAT is the density altitude I’m talking about.

minus a cold air intake of some description and at operating temperature you are forcing the engine to consume VERY hot air. So throw all your carb tuning out the window at that point.
The engine is now running WAY too rich. The air it’s consuming is WAY less dense and you are producing much less HP than you did on the dyno so that you could brag about it on a forum.

This is what I’m talking about in terms of density altitude. Haven’t even touched on the environment outside of the hood and how that may also affect your carb tuning and thereby performance.

disregard any 0 to 60 performance just consider even idling and throttle response with a way too rich mixture. It’s all bad. Everything from 0 to top speed from idling to cruising from stop light to stop

check ou this thread

https://www.corvetteforum.com/forums...g-results.html
go ahead and measure your underhood temps if you want to prove or disprove this.

and hey, we all gotta blow off a little steam now and again, so don’t sweat it.

Originally Posted by resdoggie

You keep going on about air density when its only relevant to about 5% of the forum members. YOUR underhood tenperatures are very hot. MINE are warm because I have a fan blowing heat away as well as some air flow going over the top my rad where I don't have any seals. My engine temps are perfect with my clutch fan. But that's how my car runs. As for the carb, in the garage, you can only tune idle quality. Big deal. You can't tune main jets nor power valves nor acc pump shooters nor acc pump cams which is the major tuning. To tune those, the car needs to be driven under load with a vacuum and afr gauge. 100% of my driving is below 1000' of altitude so air density is irrelevant. And even if I had very hot underhood temps, tuning the jets would be road testing with that underhood heat and adjusted accordingly. Again, air density is irrelevant. Back in the day, carbs were adjusted at factory, maybe, and that was it. They needed to operate at 40 below zero or 110*F. Do you think people worried about air density and had their carbs tuned for each season of the year? Hell no because it was not necessary because the carb worked just fine in all temperatures and altitudes up to what, 2000'? Probably 90% of the North American population lives below 2000' or even 1000'. So air density concerns are for racers and pilots.

Originally Posted by REELAV8R

Air density is of concern for those who understand it. I can't make you understand it.

I go on about my underhood temps because that is what I'm working with. YOU have to work with what you have.
MANY of these vettes are going to have underhood temps exactly like mine. Even GM understood the effect of air density sans the cold air induction in later models.
The volume of the the stock CAI was adequate the consumption of air of the engine. A 180 HP engine does not consume much air.
So if you have a 400 HP engine the CAI may need to be altered to accommodate the additional volume of air.

And of course back in the day when the carb was the ONLY option for an engine it was used.
95% of people have no idea what air density even is, so why would they concern themselves with it? That does not make it any less relevant or real.
All they knew was that when they took that camping trip to Yosemite the car/truck was real gutless and puked lots of black smoke out the tail pipe.

You can't tune a carb properly by trying to do so with 160* intake air. Even the main jets accommodate the mixture by altitude. In main jet selection charts you will notice that the appropriate jet is chosen by altitude. Pressure altitude only.
If you increase that altitude significantly through heat and thereby lack of air density (density altitude) the pressure altitude that the jet is rated for is of little value.

Just as an example if I take a sea level pressure altitude and raised the temperature to even 110* F I have increased the density altitude to 3500 feet. Is that relevant to the operation of the carb and engine? How about up to 160*? now you're at 5000 ft density altitude intake air. Is that going to have an effect on your jetting?

Believe what you want...or don't. It's of no consequence to me. I'm just trying to point out the science here. It is relevant.

Originally Posted by REELAV8R

Air density is of concern for those who understand it....
Just as an example if I take a sea level pressure altitude and raised the temperature to even 110* F I have increased the density altitude to 3500 feet. Is that relevant to the operation of the carb and engine? How about up to 160*? now you're at 5000 ft density altitude intake air. Is that going to have an effect on your jetting?

Originally Posted by 67:72

Huh. I never considered air temperature in conjunction with physical altitude creating a higher or lower effective altitude (I'm supposing this is what you mean by "density altitude".) Makes sense but I just never connected it in relation to engine tuning.

I lived in Flagstaff, AZ, for quite a few years (7200' above sea level). As I recall, we ran leaner and adjusted when we went down to Phoenix or Tucson for events. It's been decades since I moved away but I recall rejetting too. Just googled charts showing temp/altitude/density altitude... so on a summer day in Flagstaff at 80°F, the density altitude is close to 10,000 feet... If I'm understanding the chart correcctly, jeez!

Out of curiosity, would you know if dealerships, in high altitude communities, had to retune new cars from the factory?