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im wanting to add something like a little 75 wet shot of nitrous to my 355 rebuilt motor with some hypereutectic pistons but i keep seeing people talk about it ruining things? can someone tell me what the problem is here? ive heard you have to be careful with dry nitrous but i havent heard of the wet stuff until i was snooping around this forum...
75 HP nos shot well not hurt your 350. Just be sure to have the fuel side of the system supplied with a proper supply of fuel.
go for it, 355 cube v8's are what all the the popular supplier rate their pill settings on, smaller engines get a harder hit, larger ones a softer hit. as for the engine, even if its a cast piston unbalanced stocker u can add as much as 175bhp safly given a good adjustable fuel pressure system and automatically retarding ignition system u can actually run as much as 200bhp hits so long as u do not make it all 1 hit, stage it with say 75bhp n 1* of retard, the add on the remaining 125bhp with an additional 3* retard, maintain a min of 6psi FP with all stages activated and WOT with a carb, min of normal plus 1 PSI FP at WOT and full activation with an MFI or EFI systems....enjoy....
a good investment toward consistancy would b a bottle warmer for those cooler days n night to maintain a consistant bottle pressure which makes for consistancy in ur passes from 1st to last pass per fill.
(system work best when bottle presure is consistantly at or near 1200 PSI)
wow! thanks for the advice guys! i dont quite understand the fuel aspect of it all? could someone maybe explain this part to me? ive got a Q jet carb and i though with carbs you're only supposed to have a maximum 5 psi pressure with a carb?
thanks for the advice guys!
Q-Jets are indeed the most sensitive carb there ever was, save for perhaps a Lucas, diff is the Q-Jet is likely the most EFFECTIVE and by far the most efficient carb, its hard to get closer than a Q-Jet to EFI or MFI without actually having same, its reputation as a failed carb is wholely undeserved, used within its intended operational envelope its among the best and comes in standard sizes as large as 835CFM. Remewber that the Thermo-Quad, The AVS( which is what the Edelbrock series carbs are with an Edelebrock name plate on em), The Q-Jet are ALL Carter Carburetors. When Carter no longer had manufacturers contracts for Carb they sold PRODUCTION/Distribution and sales rights to Edelbrock and others in the After market.
AS a general rule NO carb much cares for more than 6psi @ WOT, however, in good shape u can get reasonable needle n seat life at as much as 8PSI. This is fine with spray, since if ur past 6psi @ WOT ur over the recommended FP for any carbed wet plate application using spray anyway.
Nitrous and fuel jets for spray systems are calibrated based on the recommended fuel pressure for the fuel system in which they are used, if u use LESS pressure u lean up the mix and imparts a harder hit, if u use MORE u fatten up the mixture and soften the hit as well as lower the power increase u get when u engage.
Think of Turbo Chargers, Superchargers and Nitrous Oxide as 3 relatively destinct ways to achieve the same final end. To grasp this, realize that tho fuel is an accellerant it isn't the fuel that actually DRIVES the engine, it is the oxygen content of ur mixture. Of those gases included in free air, oxygen is that one which reacts the most quickly and violently to the application of heat.
The Former 2 increase the oxygen content in the combustion chamber by simply puttin more air per combustion cycle into the cylinder, Nitrous does so by introducing a mixture that is MORE oxygen laden at normal atmopheric pressures than is normal free air...
Free air under the best of circumstances, at ther most favorable atmopheric conditions is never going to exceed more than 15 per cent oxygen, usually right around 12 per cent and in cities like LA or NYC this may even get down closer to 10 per cent, Nitous Oxide on the other hand is by volume AND weight 33.333333333 per cent Oxygen in its purest form, which would b medical grade(laughing gas); commercial grade averages by supplier 30 per cent since there r other gases introduced to discourage misuse, which is what gives it its scent, medical grade is odorless and tasteless. By introducing Nitrous oxide into the incoming charge u effectively raise the oxygen content of ur charge and COOL same prior to ignition to boot since u replace a portion of the AIR the engine ingests with a more oxygen rich gas than is free air. Theoreticallly, the introduction of enough oxygen into the charge can MAXIMIZE Thermal Efficiency Potential to 100 per cent, thus allowing u to produce the max amount of power the engine is capable of producein at its size which controls the absolute amount of air the engine can move thru itself w/o boost in the inlet. With this u understand why spray is NOT equal in its power production capabilities as is a turbo or supercharger, since either of the latter can introduce more oxygen into the engine than it could possibly move under normal atmopheric pressures in the inlet by simply introducing MORE air from which to extract oxygen, while nitrous introduces more oxygen it also reduces the amount of FREE air that is ingested in each combustion cycle by replacing a replacing a reletively small amount of the free air with Nitrous OXIDE, 2 parts Nitrogen and 1 part oxygen per molecule or at the molecular structure as its known. Thus u simply can not move any more sheer volume thru an engine than its size dictates w/o pressurizing the inlet. u can maximize the amount of power capable of being produced by the amount of air volume being moved to 100 per cent but u can NOT exceed that amount, the reason u can with the super or turbo charger is cause u can MOVE MORE AIR thru the engine, both by increaseing the containment size of the inlet system and the introduction of more pressure with which to introduce same into the engine at each opening of the intake valve.
As far as use with a carb, any system u buy u buy for the type of induction system u have, simply follow all recommendations and installation instructions to the letter, buy a quality system and employ a carefull quality installation and u'll have no problems.
A note, trying to shoot more than 300bhp of spray thru an engine which employs an exhaust that is not turbo or supercharged is a wasted effort, even if u have a plate/jet system that will flow more than that, the back pressure created in ANY type of exhaust system under NA conditions will negate any gain u might get from it....
Besides, with a nitous system, u are limited to how much u can put into the engine by the number and size of the openings in the spray bars and the amount of pressure u can maintain in the bottle, any wet plate either for a carbed, EFI or MFI system is going to b maxed out by 300-350bhp. U may b able to flow as much as 600bhp or more thru a complex and dedicated FOGGER system but this only effective if the engine has that amount of power left to b produced by Max thermal efficiency; IE: u have an engine size capable of producing 1000 BHP NA and u actually make 800 of that w/o the intro of spray, u can spray all u want u'll only get another 200. The addage that there is no REPLACEMENT for displacement applies no matter how u go about power production. the larger the engine the more power its CAPABLE of producing under any circumstances u may choose to use to do so.
That is why tho spray, super and turbo chargers are indeed great substitutes for cubes, they are not a replacement and only surfice so long as the larger engine does not employ them as well.
With engine crafting for power production its important that one understand what works, how it works, where and when it works, but if u hope to do much to make the engine work better u must also understand WHY it works, if u don't understand WHY something works ur behind the 8 ball tryin to make it work better than it already does.
AS i say, spray has great advantages, but like its other 2 simular counterparts it also has DISADVANTAGES as well and thus is NOT for everyone in EVERY situation. Remeber that the best performing ride is the one that employs the best WORKING combination of factors,in THAT race; probally the most important ingrediants in same are the proficiency of the operator and the cheif wrench/builder. In fact, the greater ur proficiency in these two areas the less u need in others in order to achieve any desired end with ur ride.
My preference for spray is based on the same reason most used by those who swear its a cheat, i'de rather just make all the power i can on the mtr alone and then try to better apply that power than the guy in the other lane does with whatever amount he makes. Spray is actually NOT a power adder in that it CAN'T add any more power than the engine is capable of producing normally aspirated at PEAK thermal efficiency.
There is one other seldom considered factor in power production with ur engine, its called BRAKE FUEL CONSUMPTION, it dictates that no matter what size or type of engine u use to create any given amount of power requires the same amount of fuel consumption. U may have 2 engines producing 300bhp at some given point or other, ALL other things between these 2 engines may b diff, but at the production of 300bhp, the fuel consumption is going to b the same, tho each engine may create this amount of power at vastly diff RPM levels in vastly diff ways.
Also, no matter how u plan to achieve any amount of power from ur engine the short block must b able to contain the amount of power made w/o failure or at least w/o failure too premature, the end game is that the more power u make from ANY engine the shorter the life of same is going to b all else equal. This is proven by the fact that ANY ENGINE is going to have a shorter life the longer its held at WOT/MAX POWER PRODUCTION than will one that lives its life in moderation at some point BELOW its max power out put. More power requires more heat and friction to produce and we all know that the level of heat and friction dictates engine life more so than does any other factors.
In Effect power is actually made based on the effciency of ur inlet(Heads, valves, Valve train etc..) and exhaust, the short block simply must have sutable durability to contain same.
A LOT of good knowledge there mrwizard i appreciate you taking the time to explain stuff. i think thats awesome! thanks for the help everyone !
thermoquads were made by carter and were a spread bore with two float bowls and a plastic main bodys and were put on mopars never seen any of them on a chevy . the only ones i have seen was the ones i put on. i did use them back in the 80s on my 396/402/454 , the carter AFB is the one edelbrock makes the thunder AVS is just ahop up AFB with qwik tune on the back air door and body is drilled for dual feed lines .i have never seen edlebrock sell new thermo quads????????????????????? but did build a Q jet and i think merc marine did build them for some time i know they did use the two barrel from rochester / gm
u r more than welcome Chev....remember, don't STOP thinking for yourself when and if u do decide to use the spray, believe it or not, no matter how much info i impart there is always something more and perhaps better u can TEACH urself so long as u use the info as a basis to research ur own particular application and dial it in, if u discover anything NEW or learn anything new, pass it along...please
the thermo quad, to me, is, even above the Edelbrock/AVS are the best cross between the performance of a Q-Jet and a square bore holley of some kind......the holley build and metering system is such that if u use a carb ur not likely to produce more peak power with any other carb, however the Q-Jet and to a great extent the Thermo quad have MUCH better throttle response especially at low RPM, and their better metering almost always results in better MPG and drivability bhp for bhp produced. These also provide , especially the Carter AVS style Edelbrocks, a braoder and most often much flatter power curve than will the Holley albeit with a bit less peak power production.
To build a COMBINATION Hot rod/street rod/drag car whatever comes down to a series of sacrafices in the aim of MORE power production, the Term speed costs does not jus apply to money spent.
It costs in other areas as well, mostly drivability comfort and convienience. Be total honest with urself in ur build, decide exactly what u hope the finished project will serve as and what ur willing to sacrafice to achieve that goal and b sure that YOU can proficiently operate ur end since u can have the baddest ride in town, if u can't effectively use it ur gonna spend a lotta races reading lic plates.
a Q-Jet or Thermo Quad is a much better choice for use in a predominantly street driven application where overall perfomance is not intended to amount to too much sacrafice in drivability, and in many instances may well lead to even better performance than would the most power productive Holley u could use, the flip side is that they are a bit more finiky and complex to tweek and tune, again, those sacrafices, and, if u run other than a Mopar set-up u'll need some fgab and adapt techniques to apply the Thermo Quad, mostly the linkage.
i like the thermo quad over the Q jet the Q jets is not a bad carb and i did save more them one if was a holley it would been junk . when i work in the boat yard they would sometimes sit for many years on end. and did get very funky .but i could make the work .same with the AFB . had one that sat for many years and the pump was dry .it did have a leather pump seal .she soak up some fuel seal up and ran like a top .you could not do that with a holley. so for mild street use i like the afb and thermo quads .but i like my 9377 holleys for street use. i have been using one for over 22 years on the street .other then that i have not much use for holleys .i do not look at plates much;)
alright will do mrwizard! thanks again ... take it easy
I am a hard Holley fan, i just realize that it has limitations and quirks that make it unsuitable for ALL applications. I have run Holley carbs since the 60's when they 1st began to get really popular, but i ALSO have a vast amount of experience with the Q-Jet, which i also LIKE, and SOME experience with the thermo quad which i also like. the latter 2 of these are far and away better for most predominantly street application than is the former, although a Holley is far more infinately tunable and adaptable than its somewhat simplistic design would belie.....
Properly sized and tweeked, u can't beat the Holley for peak power production, thats why there are so many varetions out there BASED on the Holley, Ford even built once a FOMOCO dupe of the Holley design back when they still owned Bendix-Moraine. The greatest boone to the Holley for peak power production is probally BOWL capacity. once u get into the truly hgh revin hgh draw Big Blocks, even the dual bowl Thermo quads and Q-jets are going to have to b used in multiples just to b able to KEEP up with the mtr because ur jus not goin to get them to tolerate the kinda fuel pressure ur going to need to KEEP the bowls full for a complete pass or in hard cornering, smewhere ur going to starve, even if its not to the point of being an ear or seat of the pants starvation....from my Oldsmobile and Pontiac Tri-Power fanatic days, i learned beyond a doubt that multiple carbs eventually need to multiple headaches, thats the reasoning behind the prolifiration of the Dominator series carbs, ONE carb big enuff to feed a lotta mtr, which is a logical progression on the theme Holley began back with their original 900cfm 3 barrel race carb....
i had i in line auto lite look like a holley 4500 in a line .you ever have one of them?
yea i did pat, actually it was on my 1st hot rod Ford when i got it, 1965 390 4gear Galaxie 2dr
i built top plate for it to fit on a holley tunnle ram for a bbc .was on my black GTO back in the late 80s:3dSMILE:Quote:
Originally Posted by MrWizard455
Good old fashioned back yard hot rod engineering, or as the youngins would say "old school".