I Cant make up my mind vs the t56 or the tko 5 speed. TKO can handle more but not as long an overdrive and i have 410's. The TKO would also be ALOT easier to install and be a little bit cheaper to do as well. Anyone have the TKO tranny?? Like it / dislike it and why?



Thanks,

 

I'm happy so far overall. every once in a while it will try to grind a bit if I downshift to 3rd gear too quick (like trying to pass someone on the highway) but otherwise it is a great tranny for me so far. At part throttle and normal street conditions it shifts really nice like an OE trans, and when I powershift it at the track or hammer around on the autocross course it never gives me fits.

 

I like mine. Not too bad with 4.11's...I turn 2500 rpms at 70mph. Biggest deal is getting a shifter that ends up in the correct location.

 

Rockland makes a T56 to handle 1000hp with a warranty. I'd take the extra OD gear. - They also make one rated for 750hp(cheaper), which is what I'm gonna order.

 

Yea i would go with the t56 but im thinking it going to be to big of a hassle finding all the parts and putting it all in. Thats why i was going to go with a direct bolt in t5. How much did the tko trannies run you guys? Also does the pro 5.0 shifter from the stock t5 bolt up to this, and is there anything you have to do to make the tranny fit? Or is it the same as putting a normal t5 in?


Thanks,

 

no, a T5 shifter won't fit. Also, if you get a T56 from Rockland, it comes with the plate to bolt it to a standard old-style manual trans bellhousing.

 

GET THE T56!! You wont be disapointed and the install is a breeze, just about every third gen aftermarket manufacture makes the parts you would need.

 

If you get the T-56 from RSG you will have fewer options in terms of support later on as they are The Only Ones that know what goes into one of their high perf. trans. The TKO is able to meet your needs without add-ons from an aftermarket vendor- it's good from the manufacturer. That also means that you can get parts for it from any vendor. It is also warranteed by the manufacturer, as opposed to somebody that works on it 2nd hand. RSG is probably very good, but I'd be willing to bet that the support from Tremec will be better...

 

what are you talking about!? you can buy performance internals for T56's just about anywere, and its all pretty common T56 knowledge what you have to do to make them withstand serious abuse (steel forks and so on). I would think the added up front cost would be offset by the better fuel economy with the 6th gear. and do you think you would be putting enough to it to break one? I thought stock they could handle 450-500?

L.I.N.Y you wont have anything to worry about with a stock t56 if all you have is a 305

 

I did not see that he had a 305. In that case the stock T56 is fine and accessible. I misread and thought he was referring to the TKO500/600.

 

Im sorry i need to update my sig. i have a little more then mild 350 pushing close to 400 hp at the crank so i need something capable of handling more then the t5. Also i drive the car everyday and i know with the tko i could do it within one day with no problem, but the t56 im thinking might take me like a week to do. Then with all the parts i need and the cost of the t56 alone i think it will be well overe 2500, im i correct?

I also like that the tko tranny is Brand New, which means perfect synchros no binding gears or anything of that sort, which is not always true with a used tranny

 

2500 is a CRAZY high number for a t56. you should be around 1200 all said and done. most ppl sell them as complete drop outs so all you would need is a crossmember. the master and slave will bolt up to your pedels. BTW how much is the new TKO costing you?

 

t56 is the better cheaper route. if you have a t5 now a t56 swap is easy all you need is the tranny and an adapter plate and piliot. under 1000$ swap. check ebay for t56 for sale. they never last long in the classifieds over here i just finaly got one and i have been looking forever on here.

Isnt this a drivetrain question instead of suspension?

 

I cant find anything for 1200 like you said. The trannies i see are going for 1200 alone let alone the entire package. The tko is around $1900. I have no clue where you get these prices from but for under $1000 an entire swap? If you wanna sell yours you just picked up and make a nice profit on it let me know

 

nope dont want to sell it theres one right now on camaroz28.com http://web.camaross.com/classifieds/...ct=1751&cat=27 for $800 obo. offer him 700 shipped and buy a adapter plate(235) and piliot bushing(40). then all you need to do is fab a tranny crossmember or buy one. Should keep you around 1000.

anyone who ask $1200 for just a used tranny is out of there mind.

 

I paid 900 for mine without a clutch or pressure plate, the only thing it came with was the master and slave. if you cant find one complete for under 1200 your not looking hard enough. en beef and 1900 for a TKO sounds like you would be better with a t56, rockland can do a refresh for 600-800 they do really good work my buddy just got his back and they said it should easily handle 800hp and he paid 1800, all you would need is a stock rebuild with a couple extra hi po parts in there. So all said and done a bran new (rebuilt) t56 should run you the same as TKO and handle just as much horse power but you do get a 6th gear. To be honest with you there is no reason to beef up the t56, I know they can handle in the 450-500 range. If I was you I wouldnt even think twice about this, ask anyone here that has switched to a T56 and they will all tell you it was one of the best "mods" they did.

 

92rs85berlintta: First off that tranny is from an LS1 And it needs synchros...Also You need more then a tranny, an adapter plate, and a pilot bushing to install a t56. You should do your homework first.

Tricked-Out-Toy: Yea 1800 for a beefed up t56 but i still have to buy soo many other parts. Well Over $500

I still cant decide which one is the better deal. Im still leaning towards the tko unless i find a good deal. ($1400 for everything)

 

All you need if you have a t5 already is a ls1 tranny and an adapter plate. I did my homework.... mcloed makes and adapter to fit the t5 parts to the ls1 transmission. Dont insult me because you didnt do your homework it makes you sound stupid when after all im trying to help you and save you money. Synchros is nothing and a local shop might charge you 100 at the most to put them in. Theres one that just ending off ebay for 6-7ish with nothing wrong with it and it has almost everything. Dont be so lazy and look around you will find them all day long under 900. Go ahead and buy a t5 for a mild 350 and waste 2000$. The t56 will handle anything you can throw at it with your engine. Remember its the same transmission people run slicks with there ls1's and run 12's on.

 

tko's tend to be notchy like some people have already said......not the smoothest shifting trans on earth, but very very tough.

i had a tko II behind my 383 making about 525fwhp for 4 years with 100's of passes on slicks on it, never made a peep.....the overdrive is fine too, its a .68 (theres a .85 i believe too for road racing available) and i have 4.11's.....car drives at about 3000rpm at 80mph on the highway

now i have the tko 600 and its been just as good.....the car pulls the wheels on launches and has eaten a couple of clutches but ZERO transmission problems......its also alot smaller and lighter than a t56.....besides EVERYONE and their brother has a t56 now....and i hate doing what everyone else does lol.
----------

to do an entire tko setup if you already have a manual trans it costs around 2000 bucks.

 

Oh so You dont need a new Clutch,bellhousing,flywheel,pressure plate, slave cylinder and all the other parts for this to work? I didnt know this i thought it was all different?
----------
383 i think you made up my mind. Im going with thr tko 600. They make a .64 ovedrive as well i think im going to go with that one.

 

No you dont need that stuff. It is all different but like i said theres an adapter and piliot you need to make it work.

 

Wait So Your telling me those are the ONLY two things you need to put a t56 in a thirdgen? NOTHING else?

I find that really really hard to believe. Actually i dont believe it.

 

I just went through this exact same decision with my car. For a while I was going to go with a T56 but then when you actually do all the math, the TKO makes a lot more sense.

Now I have a TKO in my car from Forte's Parts Connection (Burlington, MA). Everything you need comes in the F-Late conversion package. It is the tranny, tranny to bellhousing adapter plate and cross member relocation shims.

People blow T56's all day. Sure you can run 12's w/slicks on a T56 but for how long? Look what 383 is doing with his car on the TKO. The T56 will detonate a lot sooner than the TKO will. There is a reason people with stout motors who frequent the 1/4 mile run these trannies.

So far my TKO is really nice. I have no complaints and its nice knowing the tranny I have in my car is overkill for the motor (~400hp). Chances are I will never blow it up. With the T56 I knew it would not hold up in the long run.

I was unaware you can adapt a T56 to run behind the stock T5 bell with the stock clutch setup. It all comes down to dollars. If your going to drive the car on the street go with the T56 but if you want a tranny that you can launch all day long with on slicks, get the TKO.

 

no you need a crossmember and small hardware and tq arm mount too. Like i said you must be converting from a t5 obviously.

You can swap viper internals into a t56 as well if you really were to think that your mild 350 would hurt the transmission, which it wont.

 

I you can wait till the end of the year, Tremec is going to realese the
T-56-700. An OEM T-56 that will support 700hp. I think it's going to be unveiled a this years SEMA show.

 

HAHAHA your crazy! I have done it along with 3 of my friends for less than 1200. 92rs85berlintta has shown 2 places to get a T56 for less than 900. I would like to know what magical parts your buying to bring the price to 2000????

L.I.N.Y.92CAMARO: why are you buying a LS1 t56? A LT1 T56 is a direct bolt up to your L98 block, and when and if you want to swap to an LS1 engine just sell the LT1 T56, you shouldnt have a problem getting atleast what you paid for it. I can see you already want to waste 2000 on a TKO (gloified T5) and you just posted on here to get ppl to agree with you. A T56 is the best all around manual tranny you can put in these cars bar none!

 

I bought the ls1 t56 not him ..LOL. Its an easier swap if you already have a t5. Mcloed make and adapter that bolts it diredtly to your t5 housing using you original clutch bellhousing and hydraulics. Its so much cheaper and easier that way. you just need the two parts i was talking about.

L.I.N.Y.92CAMARO: check out the thread "g-force not standing behind there product" This will give you some real world experience of the good old t5 with 2000$ worth of parts in it.

 

are you on drugs dude? i've bought 2 tko's brand new, from forte's.....im pretty sure i know what i paid for them.....has nothing to do with a t56..,......everyone's done everything with 3 of their friends......what are you 12?

a tko IS NOT a glorified t5, the case dimensions and structure are NOT EVEN REMOTELY THE SAME.....the tko is a tremec 3550 case with much stronger internals, and revised syncros, and much stronger alloy gears and shafts......the case is far superior (and alot larger) than the t5 case.

so its obvious you don't know anything about transmissions, and i'll go ahead and assume you act similarly with regards to everything else involving cars.......so like i said before, a t56 is great if you want to follow the crowd and buy a 130lb transmission with an extra gear thats not good for anything but saving a few bucks on gas. the TKO is a purpose built racing transmission and will handle alot more torque, not to mention massive abuse.

as i said before, i've owned 2 of these transmissions and visciously beat them on 1.6x short times on sticky tires for 5 years and had ZERO problems with them........the swap costs aboust 2000 bucks.

it will cost you about the same by the time you get done with a t56.....you'll have to hunt up a few parts here and there, and by the time you get done it will cost you more than you think.......i can tell you exactly what the tremec swap costs because i've done it twice already.

if you want to listen to turds like this guy thats fine......take a look at my threads on the power adder board and see what im up to if you want some proof of credibility and knowledge.....also feel free search up on tko's on the board, you'll find alot of posts from me over the past 5 years.
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PS.....

just to reiterate........the t5 shares NO design features, dimensions, parts etc.....with the tr-3550 series transmissions......which includes the 3550, tko, tko II, tko 500, and tko 600

 

OPPS I miss read it, I thought you said it cost 2000 for a T56 swap my bad. oh and the glorified T5 remark was a little harsh.

ALL Im saying is for his application a T56 (stock) would cost less and be just as reliable as a TKO BUT you get the 6th gear which is GREAT for gas milage! so please tell me why you think he should get a TKO over a T56. we have already shown that you can easily purchase one for under 1000 so dont say price. Its easily verifiable that a STOCK T56 can handle pretty much anything a Cam/Bolt On L98 can throw at it.

Oh and that was an ******* remark calling me a Turd??? WTF are you 12??

 

Yep this thread just got set on fire LOL cant we all just get along.



Not just because im partial to the t56 but because its simply a cheaper smarter thing to do in his shoes. If you cant swap one in for around 1k your not doing somthing right. Im actually working on starting a thread regarding the ls1 t56 swap with detailed pics and price sheet because it seems theres a lack of knowledge on here about them. I just studied up on it and its easier then most think. Stay tuned for that The t56 has more upgradablilty than the T5 and I say that with confidence knowing that im correct. If not feel free to prove me wrong. He wasnt saying the tko was trash just a t56 is more rational decision since it seems like this guys mild 350 is a daily driver. If it is eventualy you will save in gas money what you paid for the swap. the 56 spins 1700-2000rpm @ 75mph..not bad only 800 over idle were as a 5 speed runs around 2500-3000 @ 75mph and your running in your lower powerband killing the gas and creating more wear on your engine.

 

 

I have an 86 z with a 350. I got an LS1 t56 off ebay for $850. I am in no hurry to put it in, so I started asking on different sites what would be needed to do it the best, and most economical way. I asked excatly what would be needed, as I didn't want to get started and find out I needed this or that, etc. From the few answers I got (and a lot said dump the LS1 and get an LT1) this is what I BELIEVE is needed. 350, existing T5 clutch, pp, throw out bearing, hydraulics, and bell housing. Add Macleod adapter and extended pilot bearing, modded - or purchased - cross member, open tunnel for shifter approx 2".

Now, do I, or don't I have to get a shortened driveshaft? There seems to be a difference of opinion on this. My swap may be a little different when it's all said and done, because I am also installing an 8 3/4" Mopar rear, with 4.30 gaers and posi, that has been modified to "bolt in" the Camaro. With the 350 w/Vortec heads, 600 cfm carb, Ls1 t56 tranny, and Mopar rear, it'll probably be a one-of-a-kind.

 

Well with the mopar rear i wouldnt exactly know. but with your stock 10 bolt you DO NOT need any driveshaft modifications at all. Theres like 1/4 of an inch difference is all .. no big deal. So if you werent going to need one before you dont need one now. my total price list for the swap is as follows including all shipping.

$850 for the ls1 t56 shipped
250 for adapter shipped
50 for the piloit shipped
200 x member shipped
-----
1350
-350 i sold the t5 for
-----
$1000.00 swap.

 

because doing things twice is stupid.....if you ever plan to make enough power to need a tko, get it now and be done with it......and save yourself alot of space and weight in the process

 

The t56 is rated for 400-550lbs of torque... the tko is rated for 400-600lbs. Is $1000 more dollars really worth the 50lbs of torque that most people never produce?? Not in my book or my wallet. The weight is small trade off for 6th gear. We add hundreds of pounds doing sfc's rollcages ect... So its really not that big of a deal unless its a drag car.. in wich in this case its not even close.

 

Wow I hope the rest of your posts arent as pointless and one sided as this one! Your the one being stupid. if I went to rockland as said I want to spend 2000 on a T56 they would build me one that would make a TKO look STUPID! I think I see why you have such hostility toward the T56. You bought a TKO and never did your homework so you spent more and you dont have a 6th gear! I mean come on do a and you will see plenty of ppl putting down serious HP through a T56 with 0 problems. If you cant find anyone on thirdgen go to CZ28 there is PLENTY of ppl in the 500-550 hp range.

 

the issue here isn't what they're rated for......its what they do in the real world.....the gearset in a tko transmission is much stronger than a t56.....they are rated for 600 (for the tko 600) but even the old tko II's routinely held solid deep into the nines......t56's don't fare to well down there without some serious work........i've seen more than a couple twisted/broken/bent output and input shafts along with scattered transmissions.

 

I believe the main shaft to countershaft spacing on the TKO is greater, meaning bigger stronger gears. The case is also really stout, keeping the gears firmly located. I have a TKO from fortes, not so much as a wimper on street tires with 35,000 miles. It shifts smoothly and fast with a hurst shifter. That said, i do not drag race my car (originally thought i might) when i bought the TKO the better T56's weren't available yet, and the factory ones had a reputation for being weaker than people were willing to admit. If i had to do it again, knowing that my car would be on street tires and street driven i would opt for a closer ratio T-56. The TKO is great but first gear is very short, the 1-2 rpm drop seems a little too great for optimum perf, and the od to 4th spacing is too great for highway driving. I would like the .62 6th with the .8ish 5th and a sub 3.0 first gear. That is for my setup based on my experience. If i was interested in drag racing or absolute reliability i would go with the heaviest duty TKO available.

 

alright alright....
I personally am going with Rocklands 750hp T56. It's got the steel shift forks, the hardened input/output shafts, and the HD carbon fiber syncros. It's around $2300 shipped to my door. That's brand-new, even a new case, with a warranty. It's even built to bolt to a standard chevy bellhousing. After driving a buddies' mustang with a TKO500, I'm just not impressed. The thing is almost impossible to straight shift, shifts kinda clunk for town use, and isn't enough lighter to talk about. It is a HD trans, but not really any stonger for the $ than a built T56.
- 6 vs 5. - IMO, if you have driven street car, there's no question. T56. 5th gear is an in town OD, 6th highway. If you're more worried about drag racing, then why consider a TKO when you should be looking more at a Jerrico or Liberty that you can beat the crap out of, plus the no clutch, no problems verti-gate shifter?

 

I think thats a good choice, but you should consider the ratios first, do you know what they are?? i don't so i cant comment.

My TKO shifts smoothly and quickly, better than my t5 ever did. I run a mustang hurst shifter, with the extra centering springs removed. I NEVER miss a shift.

as far as power ratings, i still say the TKO is stronger, by its design. Strenght ratings are VERY subjective. Do a search on the g-force t5 upgrade and you will see. Jerico's and liberty's are quite expensive (4-6 grand if i remember) and don't bolt in all that easy, besides the shifters can run a grand.

as far as overdrives go how useful they are depends on your rearend and how much low rpm grunt your motor has. Cruising @ 70 mph at 1500 rpm with a big cam probably wont save you a penny on gas and will be a sluggish dawg unless downshifted (just a point to consider).

All that said i would consider the T56-700 or whatever they are calling it based on the ratios available, in my situation.

 

ya i've never been impressed with the 6th gear in any 6 speed car i've driven.....if you're building a car and you're on this board talking about you aren't concerned about gas mileage anyways, or you're in the wrong hobby. as i said before, i cruise at right around 3000rpm doing 80mph in 5th gear.......i RARELY touch 5th gear unless im on the highway, you really need to be going over 50mph for it to be useful for driving.

 

I'm a huge fan of 6th gear. I've got the ZF6 in my Corvette, and it's great. With the TPI I've got enough torque to use 6th gear at speeds above 50mph, and it chugs right along. With the .5:1 ratio, it really pulls the rpms down. At 80mph on the highway I'm doing 2,000 RPM and getting 28mpg.

 

WOW I wasnt going to say any more in this post but DAMN the **** that comes out of your mouth err hands amazes me!!! I just finished A LE3 head and LE2 cam combo w/ LT's and 3" duals over the axle, that will put me at 430 RWHP, Im getting ready to do the hot rod POWER tour, and since ill be driving 3000 miles im hoping for the best damn milage I can get!!! and to say anyone on this board that posts about there engine isnt concered about fuel efficency is the dumbest thing i've EVER heard!!! MOST of the ppl on here have street/daily driven cars trying to make as much HP and TQ as they can all the while thinking in the back of there head about how these sudden increases in fuel will effect there cruising budget. anyway I hope maybe the rest of the ppl that read this will realize you can have a 450 RWHP street car, with a 6speed, spend less than you would on a TKO AND get decent gas milage. this isnt rocket science ppl. For a dailydriver or even a weekend warrior a Stock T56 can and will handle just about anything you can throw at it

 

wow that was really compelling.......

no it wasn't, that was a lie.

excuse me for making the assumption that most people that are interested in performance could give less of a sh*t about gas mileage.....because by and large, they don't unless of course thats your goal in the first place, and making alot of power is not the way to do that........thats fine, but if you ask me its boring as all hell.......i remember 450hp, it gets boring just like everything else after awhile.

so explain to me again, how what you've given me makes a t56 a better transmission than a tko? im not saying either is better at this point it depends what you want to do with it.......if you want to lug your engine at ultra low RPM down the highway (which is wicked fun by the way) then the 6 speed is for you.......i would venture an extremely educated guess that any car with a decent size cam will see very very minimal gas mileage improvement in 6th gear, which is what? like a .5 or something? regardless of the lower RPM, the engine isn't making alot of power at the speed, especially in a well cammed car, and therefore isn't going to be very efficient cruising that way.

im just telling you from personal experience about what i've done.....and thats made 500 some odd passes on slicks (front wheels in the air for many of them) on tko's and never had a problem.......do they break?? sure they do, but i've never been there to see it, so it can't happen that often.......i've seen plenty of t56's eat ****. which leads me to believe they aren't quite as tough......especially stock for stock......because anything else is an invalid comparison because you can build a transmission to handle anything you want.

bent shift forks, broken shafts, gears etc.

just for the record i do plan to detonate my tko600 this year
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a corvette is a pretty light car, so that makes an enormous difference.......with over 420rwhp or so, 5th gear in my car was useless for hard acceleration below 70-80

but once again thats also a function of how big the cam is, large cams make no power down in that rpm range.

 

OMG your an idiot, who the hell drives there car wide open ALL the time???? you really need to better understand how an engine works if you cant see how cruising down the highway at 2000 rpms vs 3000 rpms will result is ALOT better gas milage.

Ok so lets talk dollar for dollar here, A built T56 that can handle 700-800 hp will run you around 2300 shipped. im gonna qoute you and say a TKO rated for 600 runs for 2000. could you please give me the price of the next grade up TKO. Im trying to make a case here that if you want to go all out you can build a T56 for about the same price as a TKO. You dont see vipers, and 4thgens swapping out there T56 for a TKO 5speed!!! Im sure many of you guys have seent he same videos online with the 1000-1200 hp TT vipers launching with there "wheels up". so please just stop posting we have shown everyone that there is other options equal to or better than the TKO.

Edit*
incase you havent seen one of the many vipers heres one i found in about 2 seconds. It should make your 383 AFR look stupid
http://videos.streetfire.net/search/...8151B9123F.htm

 

Yea maybee if you have a carb.. efi technology has improved so much since the days or huge cams and 4 barrels you would have NO problem moving these cars cammed at low rpm. I know 3 people(4th gens) 1 with an ls1 and 2 with cammed lt1's that have absolutly no problem in 6th. They also get excellent gas milage and make trips to the strip on a regular basis. The ls1 puts down over 450 hp cammed and has been through 3 rears on slicks.. the t56 hasnt let out a peep of trouble. As far as people wanting to make power and not caring about fuel .. well thats kinda crazy. I swapped from a 350 carbed to lt1 cammed and save 10mpg and put down twice the power. BTW i run the cc306 the cam that supposedly has little bottom end and i have no trouble moving my car at lower rpms. To me investing 3-8k or more into an engine then running it at 3000rpm cruising speed just doesnt make sense to me. Not only are you unefficeintly wasteing gas your wearing your motor by running it at 3k for extended periods. At 3$ a gallon i dont think i would want 1mpg less than I can get.

 

it doesnt wear the motor out, when you do the kind of stuff we do, the motor is going to come apart LONG before it ever wears out, 3000rpm is not that high AT ALL.....thats where my brand new automatic truck runs on the highway at 80mph........no big deal.

can you tame a cam with tuning? ya to a certain point.......once you get over 240deg or so of lift at .050 theres only so much you can do.......the cam i have now is 252/262.....theres no tuning that out, it should have plenty of grunt due to the massive blower down low, but still its not going to be mild mannered.....

i love carburetors......why? because they aggravate efi people......efi is great, and its not that difficult to tune, but carbs are so simple, especially for racing its hard to beat the cost benefit......at WOT, a carb does exactly the same thing as efi if its properly tuned....with superior fuel atomization (you can actually run more boost through it due to the heat of vaporization).....obviously carbs will never touch efi at part throttle though

 

So wait your big bad cam makes plenty of "grunt" down low but cant cruise on the highway at 2000 rpms?
Ok lets do some math, this is simple stuff shouldn’t hurt your head to much. Lets make some assumptions, first lets assume the difference in MPG between a TKO and a T56 is a conservative 8 mpg and lets assume premium gas is $3.00 (by me its 3.20 but I’m making another point) and now lets also say a built T56 costs $500 MORE than a TKO (should be about the same no more than $300 more, but this is another point)

$500/$3.00/Gal = 166.67 gallons
166.67 gal X 8 mpg = 1333.36 miles.

So in 1330.36 mile you will have made back/saved the extra you hypothetically would have paid for a T56. AND!!! The savings keep coming in! so now lets assume again and say that you will drive your car 3000 miles in one year and the cost of a TKO is $2000 if you bought a T56 and averaged again a conservative 8mpg BETTER than you could have with a TKO it would go something like this.

$2000/ $3.00/gal = 666.67 gallons
666.67gal X 8mpg = 5333.36 miles
@ 3000 miles/per year = 1.778 years

So in this conservative model you could save in less than two years the ENTIRE cost of a TKO just by having a 6th gear!! I really don’t see what there is not to like about this???? Sorry if that math was to much for you, if you didn’t understand it you can PM me and ill try to bring it down to your level.

 

You missed the part about the supercharger. And 8MPG difference is whats called a pipe dream. Discussions like this one where each party is correct based on their own experience/needs/preferences but cant help but be defensive and assume the other party is a moron are the reason i spend so little time on this board. Your both making assumptions, and believe me i'm not taking sides. 383 has been around here for some time and is known for his fast car, but i don't think he has sat on the LIE in traffic or commuted 50 miles each way to work in it every day. The other guys your making assumptions based on ideal conditions and more modern LS1/LT1 motors. One of you guys is a hard core dragracer the others are fast street guys. Lowering RPM at cruise is good up to a point. With a big cam and little vacum its nearly impossible to get great mileage from a first gen smallblock. every time you touch the throttle your manifold vacume goes to 0. This is hard to tune because manifoild vacum is what is used to tell how much load the engine sees. My 383 is a tractor down low (224/230 roller with AFR 190 andHSR) it can pull 5th from off idle but not smoothly and no matter what i do mileage stinks driving like that, i somethimes get better mileage using only 4th gear (no not at 65+mph cruising) . A .5 OD will do me no good until about 80 mph. If you were running a drag race only setup without worry about emmissions your cam/lobe center/overlap would be selected for the best power at mid to high rpm making the situation much worse, higher rpm at cruise would be benificial to efficiency. Now the other end of the spectrum is the TPI motor someone mentioned, built for low end only, i cant for the life of me understand why GM never put it in a truck. That motor will do great with as many OD's you can throw at it. The factory camaro's came with a .7 od on a 2.73 rear!! and they cruised great.

Anyhow, thats my rant (I got to work early today) I think your both right in your respective situations. You guys need to try to understand where the other one is coming from.

 

dude are you kidding me? you're talking to someone who came 1 year from an engineering degree before i decided it wasn't for me and changed to business and graduated with a bsba instead of a bsee......i've taken more advanced mathematics than you can dream about......and this is assuming ideal conditions like laiky said, you will never be able to quantify that assumption......you are also assuming i give a **** how much it costs to fill my car up, and i don't....because thats not the point, at least not for me.....before my car got about 8mpg on a good day, and it made TONS of power.......that with with my "big bad cam".....which was 244/244 at .050 (308 adv) with ALOT of overlap......the new cam which is MUCH bigger at 252/262 actually might be milder, because its a blower cam on a wide lobe seperation.....and its going to have an f1r huffing into it......hopefully i'll have that started and running by the weekend.....check the power adder board if you wanna see pics