grumpyvette

http://www.armory.com/~greymage/resume/lt1.html http://www.helminc.com/helm/homepage.asp?r= http://www.ahdol.com/

just some info too think thru the engines state of tune effects the heat generated, vacuum leaks tend to increase heat, octane used effects the heat, your ignition timing curve effects the heat the type of coolant effects the rate heats transfered the amount ant type of oil effects the temp transfer rates a larger oil filter, and larger capacity baffeled oil pan, tends to reduce temps due to exposing a larger surface area to the air flow anything that reduces airflow thru the radiator reduces its efficiency the water pump and T-stat both effect the rate heats transfered, high flow water pumps can help the electric fans work off a sensor and the temp they turn on at can be modified, larger or additional electrical fans can be added on an auto trans car,the transmission fluid adds a good deal of heat to the radiator, adding a seperate ADDITIONAL trans cooler with a seperate ellectric fan,removes a good deal of the load from the radiator oil in the engine flowing over parts absorbs and transfers heat , having a larger baffled oil pan hanging down in the airflow under the engine helps cool the engine headers remove heat faster than stock exhaust manifolds aftermarket aluminum radiators can be far more efficient the dia. of the pullies your using does effect the coolant flow running the correct T-stat can help cooling, generally the 180F-190F is the best compromize http://www.digitalcorvettes.com/forums/showthread.php?t=81691 http://www.becool.com/ http://www.dewitts.com/pages/categoryresults.asp?catID=19 http://www.kevko.net/images/1090_full.gif http://www.kevko.net/wetsump_chevy.htm http://www.stefs.com/products/oilpans/circletrackwetsump.htm http://www.radiatorbarn.com/?source=overture engine oil needs to reach and stay at about 215F-240f to lube and clean correctly and burn off moisture trans fluid I try to keep under 160F,surely below 180F , Ideally I try to keep engine coolant in the engine in the 190F-200F range but don,t get overly worried below 230F. BTW I run a 190F t-stat, temp ranges should be kept within these ranges or the wear and emmissions won,t give you the long engine and trans life and low emmission levels you expect , drop the coolant temps lower and you may gain a few hp but the wear tends to get worse as the fluids can,t opperate correctly, drop the oil temp below 211 F and acids can form in the oil (bad for bearings)

IRS, if properly set up has addvantages for road racing and rought roads, for drag racing and high shock loads a live rear can be far stronger and easier to tune and on smooth roads you loose little if anything, keep in mind once you get into the under 10 second area IRS is not allowed at some tracks

if your looking to stay with IRS ID suggest a DANA44 from a corvette http://www.turbobuicks.com/members/scottiegnz/vette-irs-swap.htm http://forums.hybridz.org/showthread.php?t=97369&highlight=230+rear http://www.ffcobra.com/FAQ/irs.html looking for a live axle? Id suggest the 9" ford as its cheap and easy to work with and tons of parts available http://dfwmotorsport.com/Fairlane/9inchrearends.htm recent links to rear differential related info http://www.digitalcorvettes.com/forums/showthread.php?t=82351

miss SC seems to HAVE the SMARTS of the typical BLONDE in the blonde jokes

I can,t make out the picture, PERSONALLY ID START HERE http://www.helminc.com/helm/Result.asp?Style=&Mfg=GMC&Make=PON&Model=FIRE&Year=1988&Category=1&Keyword=&Module=&selected%5Fmedia=&mscsid=VWSTLF1TC3F99NA9AP2P7G04RHGU5VKE these might help http://92b4crs.tripod.com/86wiring/86wiringindex.html http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/ maybe this helps? Id read thru to get some ideas on the wireing! http://www.thirdgen.org/techboard/tpi/ ID ASK HERE

a bunch of pictures and some additional info/instructions on the swap would be a good asset to the sites value and sure to increase traffic once its comon knowledge it exists

anyone know a good source for the larger 10-20 lb CO2 fire extinguishers at a good/GREAT price? I got several requests and I can,t get more from my orriginal sources as they are now out of business

how many guys HAVE a CO2 extinguisher handy ? how many guys HAVE a couple CO2 or chemical fire extinguishers handy, in the garage for emergency screw ups Ive made it a practice to keep a least two, located near the doors of my garage ever since seeing the results of a buddy who managed to burn his house down due to a small engine fire that got out of hand in his garage. hopefully they never get used........but Ive come close at times in the last 40 years. my buddy was trying to start a car after installing a cam, and had the distrib timing 180 degrees out because he forgot to spin the enigne over one full turn before dropping in the distributor, the engine spit back and caught a small cup of gas he was using to prime the carb on fire, he dropped it and the cars engine compartment caught, if he had the presents of mind to grab a hose or a fire extinguisher at the time he might have been ok, but he tried to beat the fire out with a greasy towel, just making thing worse, things went down hill VERY rapidly after that! IF you work on cars LONG enought, you WILL eventually do something STUPID, get into circumstances you did not see coming or work with guys that do! so having a large CO2 extinguisher handy is a great idea, and far easier to clean up after when you are forced to use them., than dry chemical extinguishers

I stoled this off a differant site, its interesting reading... "a solid lifter flat tappet cam with 6 - 8 degrees more duration @ 0.050" than a hydraulic lifter flat tappet cam ground on the same LSA will have similar manifold vacuum and idle characteristics to the hydraulic cam. It will also have a similar powerband at low and mid-range, but will have a discernable power advantage in the higher revs after the hydraulic cam begins to fall off. At least that's been my experience. .... I prefer a solid cam" (if it will work with the EFI sensors). "There was an article a few years ago where this theory was tested on a 440 Mopar engine. I found a copy on the internet this morning, but the pages are out of sequence (goes 28, 30, 29)...... So you'll need to read it by correct page order for it to make any sense......" http://www.compcams.com/Community/Articles/Details.asp?ID=1088792917 http://www.idavette.net/hib/camcon.htm http://airflowresearch.com/articles/article002/A2-P1.htm In this tested engine, both cams were ground on 110 degree LSA and had fairly close lift after subtracting for the solid cam's valve lash. The solid cam had 8 degrees more duration @ 0.050" on intake and 10 degrees more duration on exhaust. It was an interesting comparison. Best regards, Harry" the comparison between the flat tappet and roller lifters is also of interest, but be aware there ARE trade offs, a solid roller cam won,t generally get the same lifespan as a hydrolic roller because of several factors like much higher average spring pressures and faster ramp rates keep in mind the rear gearing, stall speed on the converter, compression ratio, displacement and intake and exhaust sellected must match the cam sellected and without decent heads youll be seriously restrivcting power potential. http://www.oregoncamshaft.com/cam-basics.html http://www.symuli.com/vw/camp1.html http://www.symuli.com/vw/camp2.html http://www.auto-ware.com/combust_bytes/camspecs.html http://www.ridgenet.net/~biesiade/camdegree.htm http://www.mousemotor.com/cb_1.htm

Studs, strength and why you should use them at times ALWAYS, BEFORE INSTALLING STUDS… FIRST, READ UNDERSTAND AND FOLLOW THE MANUFACTURERS INSTUCTIONS (1) a correctly installed stud tends to be both stronger and far less likely to strip threads (2) studs tend to spread the load over a greater area (3) studs tend to allow greater clamping force and more even application of that clamping force (4) studs tend to have a NC thread in the block and a NF thread that’s used with a nut to apply the clamping loads thus lower wear on the block threads (5) studs should be installed to a minimum of twice their diameter into the block and have the threads coated with anti seize paste or thread sealant (6) never bottom out a stud, most studs have a mid band, if the hole depth allows run the stud in until that band just touches, or lightly torqued in place (read the manufacturers instructions) but not past that point. (7) Use a tap to clean the threads before installing a stud (8) Use a thread sealant if a stud enters a water jacket or oil passage (9) Studs generally come with a matched nut and washer USE THE CORRECT MATCH PARTS ALWAYS, BEFORE INSTALLING STUDS… FIRST, READ UNDERSTAND AND FOLLOW THE MANUFACTURERS INSTUCTIONS (10)youll tend to strip fewer threads in soft materials like aluminum intakes useing studs rather than bolts to mount throttle bodys or carbs (11) yes theres an exact formula for depth of threads and materials, its in the links below Now I spent a good deal of time in college doing testing and research on this very thing as its REQUIRED in engineering classes, at first you may think its boring as all get out but after awhile you see the reasons its important to know. Ill try to make this very short and simple When you thread a bolt or stud into a material several factors determine the ability of the threads to hold, the thread design itself, the material the bolt or stud is made from and the material your threading them into should be obvious, but what many people don’t understand is that the amount of thread engagement is critical as is the type of stress, if your pulling directly in line with the bolts centerline the (TENSION) is going to be different and the stress is different than if the two parts bolted together are trying to slide past each other (SHEAR). EXAMPLE If your trying to use that factory HARMONIC BALLANCER or damper bolt to re- install the damper on the crank you’ll run a high risk of stripping the threads simply because your applying a good deal of tension BEFORE the necessary amount of threads are engaged and the total surface area of those threads is far less than ideal during the first few turns under that tension/load. A STUD is not used like a BOLT, , bolts generally have tension build as the bolts tighten against the threads ,a stud is screwed in finger tight into the matched hole to its designed depth and only then is tension applied to the material and threads, usually thru use of a NUT tightened on the extended threads, and those threads are frequently finer in pitch ,having a greater total surface area to the length of engagement. example Links you may need http://www.arp-bolts.com/Catalog/Catalog.html http://www.arp-bolts.com/Tech/Tech.html http://www.arp-bolts.com/Tech/TechInstall.html http://www.toolprice.com/category/handtools.tapdiesets/?meta=gppc&gclid=CJfR-crYiY4CFRcbWAodiBpnDg http://www.sheldonbrown.com/tooltips/taps.html http://www1.mscdirect.com/CGI/GSDRVSM?PMTYPE=&SITEXT=HAND%20TAPS http://www.engineersedge.com/thread_strength/thread_minimum_length_engagement_fed-std-h28.htm If you do manage to strip threads, Drill and thread too next larger diameter bolt in NF threads, HELICOIL REPAIR is a second option that must be used in some applications http://stripe.colorado.edu/~genovaj/helicoil.htm http://www.korit.com/tapndrill.htm http://www.rfcafe.com/references/general/tap_drill_sae.htm http://www.newmantools.com/tapdrill.htm http://www.simetric.co.uk/sidrill.htm http://www.hotrodsandclassics.net/usefulinformation/tap%20sizes.htm

Ok Ill assume your looking into purchaseing or already have purchased your first DECENT SHOP welder, something like a 220 volt 180-350 amp range, in a ARC,MIG, or TIG and in most cases it both HEAVY and doesn,t come with a cart, so youll need one, so it makes an easy and necessary first project example , the three main welders in my shop MY LINCOLN ARC welder weights 630LBS THE MILLER TIG weights 930lbs the MILLER MIG is a newer model and weights only about 200lbs ALL WITHOUT the argon tank(thats easily 180lbs extra) YOUR BOUND TO HAVE A STEEL SUPPLY STORE NEAR YOU, THEY WILL GENERALLY CUT THE STEEL TO LENGTH FOR MINIMAL COST, IF you PAY extra and know the lenghts and type of steel, since cutting steel can be a P.I.T.A. without the correct tools ID strongly advise useing thier services as they are far more likely to get it correct on the first try, measure the welder base add about 3/4" for clearance in width and 10" extra length , EXAMPLE , lets say the welder measures 24" bye 40" (your cart would be 24.375" bye 50" so youll want two 50" sections of 3" angle and two 24.375 sections of 3" angle in this example and 5 sections of 1" box 24.375" long)and use that as the cart width,& length, youll of course use the real dim. of your welder) Id suggest using 3" angle iron as its both easy to weld and nearly indestructable in use, lay the angle iron on the concrete floor , on top of a sheet of junk plywood ,to tack weld with one edge flat, (THE EDGE youve had cut at a 45 degee angle) and one edge strait up an the two long edges parrallel, have the supplier cut two that width ,they weld the same way with the edge up placed inside the two sides so theres a rough 3" corner seam on each corner, and a 3" lip all the way around, USE A CARPENERS SQUARE and CHECK the 90 DEGREE CORNER STRAITNESS BEFORE DOING MORE THAN TACK WELDING, once its strait and level and tack welded move it to the welding bench or place it on a sheet of expendable plywood as you don,t want to be welding dirrectly on concrete as it bioth chips and stains if you do) youll want the corners cut at 45 degrees, so the inside flat on the floor sides shorter and the outside vertical edge is longer ,so they form a large rectangular pan with no center, but a lip thats 3" all the way around to set the welder on, buy five sections of 1" box steel the same width and weld those parralel to the front and back edge on the bottom base and the second of each pair about 3" in towards the middle but parralel, too the ends to weld the four SWIVEL caster wheels on the base too, (use at least 350-500 lb rated swivel casters so you can easily move the welder in the shop, and bolting the casters to the drilled 1" box before welding is not a bad idea here) this prevents flexing, weld the fifth 1" box steel ,vertical and weld a strap to keep the tank steady if you have an argon tank, if not the extra length can be used to store supplies......BTW some guys drop a piece of 3/4" plywood in to form a floor for the welder to sit on, (not a bad idea) QUESTIONS? BTW 1/4-3/8" thick 3" angle iron is fairly hard to screw up with bad welds and a good place to practice your first welds on those 45 degree corner seams, the 4 parrelel box steel cross braces the casters mount too further increase the stiffness and strength, when youve finnished you can paint the cart and youll have learned a good deal about how your welder works....btw most welders come with instructions as to hooking up the ground clamps, type of sticks, or wire and settings so read the instructions BEFORE STARTING AND DON,T EXPECT TO GET IT 100% CORRECT ON THE FIRST TRY _________________ if you can,t smoke the tires from a 60mph rolling start your engine needs work! looking to buy a used welder? -------------------------------------------------------------------------------- BTW, if your looking to buy a welder ID strongly advise taking a course on welding FIRST so you understand what your looking at and what to expect and so you have a good feel for what your looking to do and what equipment is necessary,then stop by a few large welding shops and ask the owner if hes ever considered upgrading his equipment? stop by a few welder dealers and ask about trade ins.? most will jump at the chance to unload older equipment if given a reasonable offer, the TRICK is knowing EXACTLY what your looking at, having a good idea as to age and condition and value and getting a DEAL, Id generally avoid anything priced higher than 1/2-1/3 of current retail. http://www.welders-direct.com/ https://weldingsupply.securesites.co...ogs.pl?UNDEF:: but be fair! include all the accessories in the bid! look around your local area for the guy or guys that do welder repairs, they can very often get you a decent deal on a used welder or point you to someone whos looking to upgrade thier current equipment that you might be able to make a good deal for on thier older equipment. just stick to name brands , and ID STRONGLY ADVISE STICKING TO WELDERS that REQUIRE a 220volt single phase electrical feed lincoln miller ESAB HOBART HTP THERMADYNE because having access to parts and service and manuals is MANDATORY if you do buy equipment thats USED ask for a demonatration on BOTH the thin sheet metal like patching a fender and exhaust pipes and thicker 1/4-3/8" thick stuff DON,t forget the welder requires a MATCHED electrical feed in your garage and it may require a tank of shield gas and may require accessories or longer cords, and consumables like wire for MIG units or sticks of filler rod for stick or tig welders, all those things add up fast!

sooner or later most guys think about engine swaps, sticking a BBC or an , LS1,LS2, LS7 in thier corvette, datsun or what ever, seems like a good IDEA. in many cases its a simple deal thats been done many times and the infos available if you research it, in others its fairly rare, (like sticking a buick turbo V6 in a corvette), one little trick Ive used is to mock up motor mounts with plexi-glass and glue, too check angles. and clearances , simply because its cheap, and you can cut, grind and drill it very easily and see thru it to mark bolt holes ETC. once youve got the model correct you duplicate it in 1/4" steel. anouther advantage is if your not skilled at welding you can hand the plex-glass model over at your local machine shop and just say "duplicate this in steel please" BTW heres some sources for parts and info :thumbsup: http://www.drivetrain.com/driveline_angle_problem.html http://www.tdperformance.com/TransDapt.html http://www2.dana.com/expert/wc.dll?DSD~dedsec~2~13~06~ http://www.drivewerks.com/tech/physic_of_racing.htm http://www.nastyz28.com/chevy-transmission-identification.php http://andersonimprovements.com/hobbies/truck/differentialid.html http://www.maliburacing.com/tech_rearend_swaps.html http://www.carnut.com/specs/rear.html http://www.carnut.com/specs/engdim.html http://www.oldengine.org/unfaq/leadfoot/trans.htm http://www.personal.kent.edu/~wbainey/BMW.htm http://www.jagsthatrun.com/Pages/Datsun_Z_V-8.html http://mywebpages.comcast.net/pparaska/drivelinemods.htm#driveshaft_loop http://www.enjenjo.com/9inch.html http://driveshaftmasters.com/troubleshootingshafts.html http://www.advanceadapters.com/ http://www.engineswaps.com/ http://www.geocities.com/z28esser/length.html http://www.thezstore.com/page/TZS/CTGY/PRC01 http://www.badasscars.com/techtips.html anytime you start thinking (THAT WON,T FIT) look at this... http://www.ntahc.org/modifiedhealeys/Photos/126Marian/Marian.htm my favorite, 470 plus inches of MOPAR HEMI in a healey, wsith a corvette rear suspension how about a V12 CORVETTE http://membres.lycos.fr/trombinoscar/c4/ct9004.html How about a 2000 Corvette drivetrain/suspension in a Honda Civic! http://ls1tech.com/forums/showthread.php?t=730443&page=1&pp=20

CONGRATS.... SOUNDS LIKE, ALOT ,of time and effort went into the car!

the LT1 intake and heads are better than average stock sbc heads and intake BUT the LT4 components are noticable better still (compare) http://www.malcams.com/legacy/misc/headflow.htm the heads, intake and compression ratio on the LT4 are differant as well as other changes http://www.fierolt1.com/lt1_vs_lt4_2.htm http://www.corvetteactioncenter.com/specs/c4/1996/lt1lt4.html BOTH engines can benefit from port work, a new cam with more durration and a higher stall converter (autos) and a rear gear ratio in the 3.73:1-4.11:1 range

the LT1 uses REVERSE coolant flow, if you look closely youll notice the intake and heads on an LT1 DON,T have provisions for a t-stat and radiator hose connection, on an LT1 those are located on the water pump while the heads swap either way, the engine can,t be made to run without extensive and fairly expensive mods. aftermarket performance heads that fit an LT1/LT4 don,t generally give any real advantage and cost a good deal more than those aftermarket performance heads for the standard gen 1 block youll also notice the distributor on the standard engine is missing, replaced by an opti-crap ignition driven by the timing cover/cam assembly on the LT1 theres nothing wrong with an LT1 that prevents you from getting good hp, but the sellection of parts is limited and sticking with MPFI in the LT1/LT4 vs swaping to a carb is USUALLY the best route, with the least problems the only advantage I see is the basic engine config is lower in over all height (more hood clearance)and can be seated back slightly further in the frame/firewall clearance, and with LT4 heads and intake its got good hp potential compared to most STOCK 350s with STOCK heads, and its a factory roller cam equiped engine http://www.malcams.com/legacy/misc/headflow.htm

one little trick Ive used is to mock up motor mounts with plexi-glass and glue, too check angles. and clearances , simply because its cheap, and you can cut, grind and drill it very easily and see thru it to mark bolt holes ETC. once youve got the model correct you duplicate it in 1/4" steel. anouther advantage is if your not skilled at welding you can hand the plex-glass model over at your local machine shop and just say "duplicate this in steel please" BTW http://www.drivetrain.com/driveline_angle_problem.html http://www.tdperformance.com/TransDapt.html http://www2.dana.com/expert/wc.dll?DSD~dedsec~2~13~06~ http://www.drivewerks.com/tech/physic_of_racing.htm http://www.advanceadapters.com/ http://www.engineswaps.com/ http://www.thezstore.com/page/TZS/CTGY/PRC01

http://carfiche.com/fiche009/ http://carfiche.com/manuals022/cars/

http://cgi.ebay.com/Hobart-Handler-187-MIG-Welder-230-Volt-180-Amp_W0QQitemZ170140678043QQihZ007QQcategoryZ113743QQssPageNameZWDVWQQrdZ1QQcmdZViewItem http://cgi.ebay.com/MILLER-MILLERMATIC-250X-WIRE-FEED-MIG-TIG-WELDER_W0QQitemZ260148771134QQihZ016QQcategoryZ113743QQssPageNameZWDVWQQrdZ1QQcmdZViewItem http://cgi.ebay.com/LINCOLN-POWER-MIG-180T-MIG-WELDER-NEW-K2472-1-NEW_W0QQitemZ130142797605QQihZ003QQcategoryZ113743QQssPageNameZWDVWQQrdZ1QQcmdZViewItem http://cgi.ebay.com/MILLERMATIC-DVI2-MIG-WELDER-COMPLETE-PACKAGE-NEW-907323_W0QQitemZ130142796184QQihZ003QQcategoryZ113743QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

comp cams has one on CD you can buy 180950 COMP Cams® CamQuest™ 6 Cam Selection Software $29.35 its useful as a starting point, to get ideas on durration,LCA,and lift that matches your application (I personally won,t use a COMP CAM, CAM in my engines, simply because they have the absolute worst tech support imaginable) the cams may be ok, but the guys answering the phones are horriably mis-informed and rude and just don,t give a $%^&

:thumbsup: heres a semi-fool proof method write a list of all factors that will influence the choice DON,T LIE tell them EXACTLY what you expect and what you have currently ,installed that the cam must work with NOW,....NOT what you intend to install later car weigh? rear gear? trans? stall speed if its an auto? displacement? COMPRESSION HEADS (flow numbers) intake type tire size intended use max rpms launch rpms MIMIMUM IDLE fuel octane carbs,mpfi? CFM ETC. call a minimum of 5 major cam companys, (6-8 is better) write down thier recommended cam type,its lift, and duration at .050 and LCA. read off the list to each manufactures tech guys, but DON,T DISCUSS IN ANY WAY WHAT OTHER MANUFACTURERS SUGGESTED AVERAGE THE RESULTS and buy the cam thats CLOSEST TOO THAT AVERAGE, this tends to give consistantly good results keep in mind solid lifters generally have an rpm advantage and roller cams generally out perform flat tappet designs but cost more http://www.crower.com/ http://www.cranecams.com/ http://www.mr-gasket.com/pdf/Chevrolet.pdf http://www.holley.com/index.asp?division=Lunati http://www.chetherbert.com/newchet.html http://www.iskycams.com/ http://www.reedcams.com/ http://www.schneidercams.com/cams/20.htm http://www.lazercams.com/CamTables.html http://www.englecams.com/ NO! ONE SIZE LARGER WON,T GENERALLY WORK BETTER

first Id point out theres alot more than just an engine envolved in a (Z)v-8 swap and ALMOST ANY (Z) in GOOD CONDITION (BODY, SUSPENSION, INTERIOR),with a running v8 car with a chevy engine will be a no brainer to swap in a replacement engine and is easily worth 2k next Id point out that while a 307 is far from ideal its possiable to pull 400 flywheel hp from one with the proper parts added

ignition component manufacturers http://www.performancemarket.com/ignition.htm oil pan manufacturers http://www.performancemarket.com/oilpan.htm brakes http://www.performancemarket.com/brakes.htm cranks http://www.performancemarket.com/cranks.htm exhaust http://www.performancemarket.com/exhaust.htm clutches http://www.performancemarket.com/clutches.htm pistons http://www.performancemarket.com/pistons.htm

a correctly designed 3" dual exhaust (IDEALLY WITH AN (X) cross over , just past the collectors to further reduce back pressure will be far supperior in most cases, as its got aproximately a 14.1 sq inch cross section vs 6.3 sq inches for a dual 2" exhaust the 2.0" dual exhaust is 2.24 times as restrictive. a recent magazine test on a SBC showed only a 7 hp differance between 2.5" and 3" dual exhaust at PEAK ENGINE HP but over the whole rpm range the 3" held a slight edge in torque and at one point (surprizingly low in the rpm range) it held an 11 hp advantage once the exhaust exits the correctly designed headers collector the less restriction past that point ,the better. I don,t see much debate room, a dual 2.5" exhaust has aproximately a 9.8 sq inch cross sectional area for flow,a dual 3" exhaust has aproximately a 14.16 sq inches cross sectional area for flow,or more than 40% less restriction. anytime youve got more than about 1-1.5 psi of back pressure your potentially restricting power potential, the OBJECT is to MAXIMIZE the cylinder scavaging to both have a more efficient burn and a more effective removal of the old burnt gasses and a faster more effective cylinder fill with the new charge from the ports, the larger the exhaust port and header the more flow, but the lower thye velocity, a ballance must be struck to maximize velocity , yet not restrict the flow. your trying to get and need as high an exhaust flow velocity as possible with as little backpressure as possible. a correctly designed header primairy and collector will maximize cylinder scavaging in the rpm band your trying to make the best power in, and its the headers primairy dia. and length and the collector design that maximizes the scavaging. but keep in mind the INTAKE runner cross section and length and the cam timing MUST also match to effectively use that scavaging. when you see a case where a cars faster with the exhaust past the header collector still connected, its a strong indication that the exhaust pipe is acting like an extended collector, its not the back pressure but the extended length thats helping scavage ther cylinders and aiding power http://www.ntxtools.com/fuelsystem/tu24a.htm http://victorylibrary.com/mopar/header-tech-c.htm http://www.engr.colostate.edu/~allan...ngth/pipe.html http://www.rbracing-rsr.com/runnertorquecalc.html the question, is will it effect the performance! its been my experiance that exhaust back pressure exceeding about 1 psi starts to reduce performance, most guys who don,t see gains from uncapping the header collectors and reducing the restriction,at the track have headers and collectors that are not scavaging correctly and the extended exhaust system behind the headers is acting like an extended collector on the headers. it quickly becomes a trade off, do you need less restriction and back pressure or better scavaging, with correctly designed headers and collectors theres little if any increase in restriction once the exhaust is hooked up. restriction too exhaust flow is the potential problem , and if the headers are not scavaging its not the increased dia. and low restriction of the larger dia, exhaust but the headers and collectors that are the problem, adding a restrictive exhaust can only hurt. a quick check can be done by screwing this in place of the O2 sensor for a check http://www.usatoolwarehouse.com/usat.../otc-7215.html

http://www.montygwilliams.com/ this may interest you