1988 Chevy K5 Blazer build - An unorthodox approach
 

I am finally posting up this love of mine :D the ball is finally starting to roll with regards to getting it back out on the road. Here is a picture -

http://s26.postimg.org/t99q79tll/image.jpg

It is the only one I have at the moment. I miss this beast... been down with a blown motor for over 2 years :(

Here are some stats on the K5:

350 TBI engine, stock but blown
700r4 transmission, stock & needs rebuild
3.73 gears
1/2 ton open axles
5200 lb. weight
~0.6 Cd :eek:


By the title, you know that I am planning something slightly unorthodox. But what is it :confused::confused:

I want to build a Miller/Atkinson cycle SBC :D
Why? for better fuel mileage of course!

If you have ever heard of the Crower Mileage Maker system, then you done and know what I am attempting to recreate. For those that do not, the Crower Mileage Maker system came about in the late 70's to early 80's. The system utilized high compression (some say as high as 17:1!) and late intake valve closing, thereby bleeding off cylinder pressure. You are left with with less of a dynamic compression ratio, but the expansion ratio and efficiency are greatly improved. This is similar to what is going on with the Prius and SkyActive Mazda engines.

I have plans for either a 355 or a 400-406 small block. Flat top pistons are to be used because personal research has shown that flat tops promote better flame travel than domed pistons. Which is critical for good combustion. I plan to use either one of these heads -

193 TBI heads; 64cc

350 Vortec heads; 64cc

305 Vortec heads; 53-58cc

Some aluminum Corvette heads on CL; 58cc

All the above heads have 160-180cc intake ports to keep air velocity up for more atominization of fuel particles and low-end torque. The combustion chamber of all these heads will keep the compression up and promotes better burn. If needed, the heads will receive a mild port and polish.

From using CSG's compression calculator, a 355 (0.030 overbore) with a compressed head gasket thickness of 0.035 with 0 dish and 0 deck clearance have the following compression ratios:

53cc - 13.06
58cc - 12.14
64cc - 11.2

A 406 (0.030 overbore) will have:

53cc - 15.43
58cc - 14.35
64cc - 13.24

All of which seem to be able to work... except the 53cc's on the 406 lol.

I have not worked out the specs for the camshaft. I know that the dynamic compression ratio will have to be greatly reduced in order to run 87 octane. If anybody has the slightest idea, I would love you to pieces to share your wisdom! I will have Crower or Elgin do me a custom cam.

This is all I have as of now. Trying to type this up before class has got me slightly scatterbrained and I know it seems like I jumping all over the place. I get excited thinking about the possibilities :D

If anyone has any questions, objections, praises for wanting to try this out, or reason for not doing this, feel free to post away. I'm thick skinned and can take any heat y'all provide :thumbup:

Let the discussion and build begin :turtle:

I like it. Is there any way to get some baseline mileage data?

I've had idle thoughts of doing something similar to my truck. I could easily tolerate 30% less power (and torque), and still get all the towing/acceleration/hill climbing performance that I need.

First order of business would be to contact Crower. I’d bet there is some old head in the Engineering Department that knows a thing or two about the Mileage Maker. He will save you a lot of expense and head-scratching. The degree to which the valves are left open will greatly affect the needed nominal combustion ratio.

In essence you are making a Chevy Prius engine. We all know they work. Atkinson engines are efficient but they lack torque. No big deal on a hybrid – the electric motor makes up the difference. You can get it back with displacement or live with less torque.

Since your 350 is blown maybe you should think of raiding a junk yard for a LS-series engine out of a later-model Chevy pickup. I have a 96 Impala (second gen 350) and even for it parts are becoming a bit of a challenge but LS-series parts are easy to come by. Get a 4.8 liter (LR4, LY2, or L20) and try to find a later model 6E80L tranny. More speeds generally equals better MPG. This lets you ditch the hunk of junk 700R4. Get the unified control brain and it becomes plug and play.

Off-roading with a torqueless Atkinson engine will be miserable. You are out of heavy snow country so I’d think about declaring the vehicle a 4x2. Gut the front diff, remove the transfer case (hundreds of pounds and a maintenance problem, plus worth a few bucks recovered for other stuff), put a 4x2 tailshaft on the transmission.

As you mention “class” I assume you are a student and don’t have much money, but something your vehicle affords you (for later on) is an aero option. Your top can be easily removed (and sold). Lay up a “fastback” top (see all the threads on aerolids for pickups. Learn to work ABS and make some fender skirts fore (a la basjoos and aerohead) and aft. Maybe a grille block. An 0.6 Cd is a tough number to fight. I’d bet a 12 degree aerolid, a grille block, and skirt of all four might knock you down to Cd = 0.50.

Even when new, I’d be astonished to hear this vehicle got better than 13 MPG. Lots of scope for improvement and at the end of the day you wind up with a roomy and sturdy vehicle.

I have just sent an e-mail to Crower asking for information on the camshaft specs. Here is the message -

"Good afternoon Crowder Cams! I am looking for information on the camshaft that came with the Crower Mileage System back in the late 70's - early 80's. If by chance the person reading this does not know what I am talking about, could they please ask around and see if someone might know? If the information can be collected, I will be buying a custom ground camshaft from Crower in the near future. Thank you and have a blessed day!"

Hopefully the declaration of giving them my cash will produce desirable results :D

JRMichler - The EPA estimates for a 1988 K5 Blazer are 11 city/16 highway with a combined average of 13. I do remember that my tanks averaged 14.25 - 14.75 with country driving. This is without knowing anything about eco-driving and having an occasional pedal-metal moment :thumbup: Best tank ever was 16.7 mpg (55-60 straight trip from Greensboro, NC to Four Oaks, NC. Minimal stops). I am with you with needing less power. The math says I will have 4.3 V6 power, with slightly more torque. I can deal with that with better FE!

Big Dave - You know exactly what I am going for :thumbup: The LSx swap is a verryyy tantalizing option that I have considered and even had suggested. It just is not viable at this point. I am a student and money is tight, so I am stuck working with what I have :( which isn't exactly too bad. I would love more gears (ahem, new 8-speed auto) though one place the 700r4 shines is its ability to coast long distances.

Case in point, my mama's Trailblazer (4.2, 4L60E, 4x4) will coast farther in gear than my ZX2 will in neutral! Coasting ability is what has net me the biggest gains so far. I know the TBR is "slippier" than the K5, but it is still a barn with curved corners :p

I had not thought about the 4x2 option, nor the ability to put an AeroCap on the Blazer! I will try to see what I can do in stock form and go from there in the future. Off-roading would suck with a torqueless motor... if it wasn't for 4-lo! That should compensate the loss of off-idle torque considerable. Almost 2:1 more torque multiplication.

And I will be glad to hear of your astonishment after you read what kind of FE I orginally got ;)

[IMG]http://s26.postimg.org/4utj01jx1/FB_...3259600510.jpg

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More pictures of my K5 from back in the day!

Me and my daddy had a discussion about the rebuild. He is adamant about dropping the 400 SBC idea completely :( I see his point in the matter. It will be cheaper in the short and long run to build up my 350. So a 355 Chevy Prius engine it will be!

I am wondering about which heads to use on this motor. I have narrowed it down between the 193 TBI heads and the 305 Vortec heads. The 193's beat the Vortrecs out in 2500 rpm & below torque production. The Vortecs have a better and smaller combustion chamber, and flow better. Both are cast iron. I have the 193's, but I can get the Vortecs @ $150-250. And sell the 193's as john boat achors lol :D

What say you???

I have read here --> http://ecomodder.com/forum/showthrea...4-a-22944.html & it appears that my cruising rpm might be on the low side. I will turn from 1350-1550 in usual 45-55 mph fashion. Will this be too low of a rpm for the motor to function correctly? If so, then should I regear or switch out transmisions with a TH350c?

I do know that I will be utilizing lean burn on the K5. There appears to be a deactivated setting within the computers that will allow the A/F ratio to go to 17.5:1 during light cruise. I will have to speak with a tuner and 1983ChevyVanG20 over on the Chevy forums to find out more about this.

I will be adding EGR back... yes, I believed the lie that EGR cost you power and mpg back in high school. I have since wised up and learned the truth. In fact, I would like to increase my EGR flow if possible! How could this be accomplished? A 454 EGR valve in place of the 350 one? Any pointers?

I feel certain that 20 mpg will be regularly attainable when it is all said and done.

I'd use standard 5.7 vortec heads milled for compression and the 700r trans.

I love this truck! The full size blazers are dope AF! I cant wait to see what you can do!

Awesome project, I've been wondering what the real world gains would come from atkinson-izing a regular engine in an existing car.

For the valve timing, I seem to remember that there was some discussion about figuring how the valve timing affected the compression ratio in the thread about swapping a Prius engine into a Toyota MR2. http://ecomodder.com/forum/showthrea...fxe-27266.html Probably worth at least a skim through.

Wouldn't a V6 swap get what you are looking for* without all the hard work?

*still a K5 V8 20mpg is bad ass.

Do it, but I guess you would like to match it with a supercharger, which would lead to what is known as Miller cycle. It had been sucessfully done in stationar/industrial and marine engines since the '30s or '40s, and is also used in some cars from Mazda and Nissan.


You can also try the mods you're planning into a V6, benefitting from the lesser weight and slightly lesser internal frictions.

Hondaguy72 - I'll be honest, I had never heard of milling a head before you mentioned it :o
It does seem like milling would give me the cc's needed for higher compression (0.006" per cc). The forum research I have done has sown that I can delete 5-6 cc's max and bump up my compression by .5 - .75 points. Soooo ---v

355 w/ milled 350 Vortec heads, 59cc, 0.035 quench, piston 0.01" in the hole, 0cc dish - 11.97 CR

355 w/ milled 305 Vortec heads, 52cc, 0.035 quench, piston 0.01" in the hole, 0cc dish - 13.26 CR

Oddly, the super small cc 305 heads put me inline with the Prius's CR.

The 700r4 is staying. I had to drive my mama's Trailblazer with the updated version of the 700r4 in it. I was coasting up to 1/4 mile on flat ground to slight inclines with out losing much speed, much better than my "good aero" ZX2.

Thanks for the info!

DirtyDave - Glad to see you could stop by, buddy! Yes, these ol' trucks are about as dope as they get :thumbup: and I did consider a 4.3 Vortec V6... with a small turbo ;) Just out of my cost range as of now! Imagine a Atkinson cycle 4.3 S-10 with a quick spooling turbo... I need to stop lol. I have to work with what I have, and good deals!

A tidbit of info: K5s came with straight 6's (4.1 & 4.8). I have to think the oil shortage was the reason for this. An acquaintance told me that he had one and it got, get this... 14 mpg. No better than my TBI 350. Although he was still able to haul a boat down to the beach with it!

vskid3 - Hot diggidty! Thank you for the thread recommendation! Someone actually mentions Crower's syatem on page 8, and the discussion on valve timing is beneficial to my project. :thumbup:

Cripple Rooster - I have looked into the supercharger idea beforehand. It just is not in my budget as of now. Well, it could be if I could put a Chevy 3.8 V6 supercharger on my 5.7 :D What would be the pros/cons of the miller cycle against the Atkinson cycle?

Read DirtyDave's comment for the V6 info. It just insn't viable at this point.

Thanks for the comment, and I will do it :thumbup:

So I may have encountered a problem earlier today. While researching some things regarding the TBI system, I saw over and over that big cams were not good for the computer.

But whyyyy? The intake reversion caused the MAP sensor to go nuts. With the Atkinson cycle, the efficiency comes from the piston pushing the cylinder mixture back into the intake manifold, a.k.a. intake reversion. So the computer is not going to be able to tell the difference, it seems. I will be contacting Brian Harris @ TBIChips.com and asking for his wisdom. He did my last chip and did an excellent job, his knowledge on these trucks is outstanding. This just might decide the project...

Stay tuned y'all!

Might want to check that fact. The 4.3 V6 didn't come out until 1985.

I will say that their mileage has always proven to be basically no better than the big engines.

Is the ride height / tires stock?

What's the plan with that?
High or low looks good either way.

I also meant to ask - what's "blown" about the current engine? I've heard that generic term used to describe everything from a stick lifter to a rod thrown through the block.

And where did 5200 lbs curb weight come from? I always heard they were more in the mid-4000's.

Adam728 - Thank you for calling out my blunder! I was wrong, it had to be a straight 6. Unless it was swapped, which doesn't make much sense due these peeps being power junkies, not economy-driven like us.

Snap beans, 2 times in a row! I got the weight wrong too! The 5200 lbs. came from my registration card & it being weighted on a scale when I took off scrap metal to the junkyard. It usually weighted 6000+ with a 600 lb. load and trailer. I GROSSLY underestimated that trailers weight! :o According to ColorodoK5, the curb weight in 1988 was 4676.

You, sir, are awesome in my book for calling my mistakes out :thumbup:

The motor blew like this: Turned a corner. The motor started sounding like a diesel and loosing power. Coasted what I could. Finally got to where I was flooring it and I was loosing speed quick. Looked at the temp. gauge... Over 300 :eek::eek::eek: Then it died and I coasted to a stop. I had steam coming out from every mating surface on the block (intake, valve covers, heads, oil pan!), the throttle body, radiator and even the tailpipes. It was quite the catastrophe. Especially since 15 minutes earlier I put over $50 of 93 in it :mad:

DirtyDave - Man, I be stuntin' on that 12" of lift and 44" LRR tires :D Eco-Hick life BO :D

Na, at the maximum I will run 33" tires on the stock suspension, with an EZ Inch up front is it needs it. I will go with stock height and 31s/15s with the 3.73 gears for the time being, in order to establish a baseline. I do plan on adding 4.10 gears down the road, in order to get the motor in its efficiency range and achieve optimal piston speed (Thank you Frank Lee, regarding OPS).

Might even lower it a couple inches down the road. If I convert to 2WD, then this is probable.

Alright y'all, Brain Harris just e-mailed me back... not looking too promising. Here is what I wrote -

Hello Mr. Harris. What I am attempting to do is replicate the Atkinson cycle on my engine. I am looking into using a camshaft the has around 300* @ 0.050 duration for the intake. I understand through research that this will cause issues with the MAP sensor. Is there any way to tune around this?
Also, is lean burn (15.5 - 17.5:1) possible with the right precautions and tuning?

Thank you sir.


Here is his response -

nope, you need a mass air sensor computer system to attempt that not a map based system. All of my attempts at running an air fuel ratio leaner than 15.2 resulted in significant loss in gas mileage.

Looking back at what I wrote, I should have mentioned that lean burn would be used cruise-only.

Soooo, any bright ideas boys and girls??

I have seen conflicting reviews on TBIChips and their ability to tune is worth a half-penny. I have heard reports that EagleMark over at Gearhead-EFI has fixed many of his chip problems. I will go over there and ask for their knowledge and second check Mr. Harris's answer.

... Not really a work around, but start over with a MAF system. Find a donor truck with a bad bottomend, 96-2000 with a 305 would get your heads, possibly a good trans, and then take everything else needed to make it run.

IIRC the 4.3L straight-6 had been phased out at that time, leaving only the 4.1L and the 4.8L ones. But there was a 4.3L V8, which was the first small-block V8 and reintroduced in the 70's due to the oil crisis, and this one lasted until the 90's in the Caprice.

To address my previous reply and your response, there is also a technique of angle milling that can reduce chamber volume even further. The 5.7 vortec heads are the best low cost solution. Small Ports, excellent port velocity. With a small custom cam you will achieve great results.

CrippleRooster - Thanks for the info on GM's I6's! I did not know about the 265 V8 being first. I assumed it was the 350 :o

hondaguy72 - Yes, I believe you are talking about angle milling. That will be done as much as possible. Though I am thinking about keeping the 193 heads. I already have them, and they can be ported and cleaned up to make near the power and flow of a Vortec. And they are torquier down low, which is needed with me going to the Atkinson Cycle.

2000mc - That idea is great! I'm probably not going Vortec though. However! I may have figured out a way around the intake reversion problem while keeping the MAP system.

I have the idea of opening the intake valve on the intake stroke @ ~90* ATDC. Then, close the intake valve @ ~140* ATDC/BDC on the intake stroke.

Lemme preach on it! With the piston traveling down the hole (All valves closed), I do believe the cylinder will have an increasing amount of suction within. As soon as the intake valve opens at the late angle, I am thinking the charge will be pulled in more vigorously, promoting turbulence and mixing on top of what the swirl ports will do. With the quick close, less charge is trapped, allowing me to the run high compression. Also, the piston is still traveling downward as the mix is done coming in and the cylinder is sealed off. My thinking is that this will further the mixing of fuel molecules. Then it's high compression and BOOM. Beautiful ignition!

Am I missing something in the above paragraph? Feel free to point out any ignorance. I am smart, but I know little about internal engine dynamics.

I will be configuring the exhaust valve timing in the next few days. I will dive into the the Mazda Skyactive engines to see how the do it. IIRC a major contributor their engine running the 14:1+- CR was an efficient exhaust.

Probably means headers for the K5 :)

Remember, it also has direct injection, which makes it less prone to pre-ignition in spite of the high compression ratio...

Am I reading that right, a total of 50 degrees of intake valve opening?

You will severely limit lift this way, as there's simply not enough time to open and close the valve very far. I would be very surprised if even 0.10" valve lift could be accomplished in that duration. Trying to push it higher is going to be a fairly violent lift/stop/close cycle, the ramp angles and valve accelerations will simply be too much.

Because of the short duration and tiny lift you'll get very, very, very poor cylinder filling. A huge compression ratio won't matter, as there won't be much mixture in the cylinder to compress. If I remember from back-in-the-day the BMW system that utilizes valve lift and duration for throttling runs a minimum of 90-100 degrees duration and 0.05-0.06" lift on the intake valve. That's for idling.



I hate to be all negative, but you are chasing a path of 35 year old technology that didn't prove itself to be worth keeping around. You're looking to do a huge tear up in terms of machining, custom cam, changing efi systems, etc, to have something that will give less power and possibly no better mpg than a more "standard" build. You yourself admit to knowing little about engines, yet seem bent on designing one. Camshaft events are the heart of an engine. A few degrees change in overlap can make an engine idle smoothly or misfire and stall. There's a LOT going on, and I would argue (strongly) it's best to follow a more well known path, at least until a very indepth understanding is developed.


If I were to do a mpg build on my truck (92 C2500, TBI 350, 5200-5300 lbs on scale) it would consist of the following. Goals would be good usable torque for towing, and decent mileage.

• Leave it a 350. No going to a 305 and the bore shrouding that goes with it, nor going 383 and the cost/slight mpg decease that comes with that.
• TBI heads - they've proven to be great for fuel efficiency and torque. For a mild build they don't give up much on Vortecs until 4000 rpm or so. With hotter cams the Vortecs start out performing the TBI's at a lower rpm.
• TPI efi system. LOOOOOONG runners, port injection. Known to make huge torque numbers, great fuel efficiency, then choking the engine to death under 5000 rpm. I think this system should have come on trucks.
• Then there's the game of cam timing, compression ratio, and quench. I'd setup for around 0.035-0.040" quench, and figure out what it needs to get there (deck milled, heads, head gasket thickness), while also keeping an eye on final compression ratio (which is based heavily on cam choice) and deciding where material needs to come or go to get to that compression ratio while holding that quench number (head, piston dish).
• Camshaft - short duration, as much lift as can be mustered, decently wide LSA. Stock cam is under 200° duration, which is great for torque, but signs off early (mid 4000's), and everyone wants to ditch them for more power. I'd rather see something still under 200°, but with more lift than the stocker. Won't get much, but a little could help.
• Long tube headers with small primaries, 1-1/2 to 1-5/8" max. Single 3" from there out.

Then it's all up to good dyno tuning. MBT sweeps, running as much closed loop as possible (or even OL lean), etc. Keep the truck down low, geared tall, and don't expect it to get Honda-like numbers. You should end up with something that has more power than stock (mostly torque), and improves mpg a fair amount.

I find the whole idea fascinating but I think your best money would be spent making yours the best SBC 350 it can be, not trying to retcon it into an Atkinson-ish model.

The TBI isn't really sophisticated enough to handle the tune you want for Atkinson function. Like the other guy said, the sensors are wrong.

Your truck is an aero disaster. I think there are likely a lot of things you can do, things that aren't too gross to look at, that will clean it up a lot. You're already doing nearly 15mpg and for a vehicle that size with that engine, that's pretty good. Tune your mill to its very best, and leave it alone.

I remember reading about Hot VWs "Mileage Motor" project - virtually none of which will make a hill of beans' difference to your project - but they found a lot of mileage after giving their test vehicle a chassis tune: setting up bearings correctly, alignment, fixing brake drag, etc.

You don't have to give your truck a heart and brain transplant in order to make it perform well, I think. I suspect you're just going for the biggest, sexiest project that has the greatest possible potential - really I think the Atkinson project does have enormous potential, but starting from a TBI SBC is probably the second-hardest way to do it (first hardest being carbureted) - but skipping past the more mundane but proven techniques that might get you closer to your goal anyway.

Think about what you are trying to do.

The OEMs have engineering resources you cannot even imagine. You can bet the farm they've taken a long hard look at this and rejected it unless it uses a direct injection engine and/or hybrid drive. You run into control issues and a loss of torque that makes the vehicle a burden to drive. The OEMs rejected it for good reasons.

Another very doable and proven effective strategy (maybe long term for you) is to ditch the automatic and get a stick. That's a slam-dunk 2 MPG improvement. there are all sorts of kits available to convert these vehicles to a NP4500 five-speed manual. The manual enables you to run a lower ration final drive. Yukon makes a 3.23 R&P set for GM 12 bolts front and rear. That's a 14% reduction in engine RPM at a given road speed If you need more torque, push the pedal and yank the stick and Viola! There it is.

A NP4500 and 3.23 gears. We're talking a 4 MPG improvement and a big improvement in reliability. You keep your 4x4 for off-road driving, and don't have to do any body work.

Not cheap, but entirely doable and you can expect a 33% increase in gas mileage.

Every time i park my F350, I feel like the Captain of the USS Nimitz trying to bring her alongside without any tugs. A short but still roomy vehicle like yours might be the answer.

I don't think any K-Blazers were ever built in a 4x2. There were some 4x2 Broncos but those are as rare as honest politicians. 3" front and 6" slam kits are available for F150s so should work on a Bronco.

4x2, moderate slam, manual transmission, a Cummins QSB (4.5 liter four-banger), 3.08 gears, and some aero cleanup. You'd have a easy to park but roomy vehicle that would scare 30 MPG.

Too pricey for a college student but within the reach of an average working person.

With my aero package right (it need work right now), diesel engine, 4x2, manual transmission, 3.08 my F350 routinely gets 27 MPG in the summer without even having to bother with aggressive hypermiling. That's not an instantanous ScanGauge reading but a three tank full (1,500 mile) average in real-world mixed driving. And all that in a 7,800 lb vehicle. A 4x2 Bronco or Blazer would come in at roughly 5,000 lb. A 37% weight reduction would have to buy you some MPG improvement even in flat terrain. 30 MPG looks attainable.

Imagine. A roomy, comfortable vehicle with all the virtues of a SUV but getting (stock) Honda Fit range mileage.

You could get a 2wd Blazer up until either late 70's or early 80's.

In the 30's and 40's when EFI was nothing but a pipe-dream, Miller-cycle engines still had to rely on carburettors. And what is nowadays labelled as Atkinson is basically a Miller without the blower.

Right, but my understanding of those was that they were generally industrial engines, tuned for a constant speed and with well known projected loads. This application would be a lot harder in my opinion.

Point of fact: a true Atkinson has a funky conrod arrangement that makes the expansion stroke longer than the compression stroke. Strictly speaking, modern "Atkinson" (or as I call them, Atkinson-ish) engines fake the effects with cams. A true Atkinson wouldn't have the contraflow effect that bollixed the sensors.

Gotta have to agree with you at some point, since a constant speed and load factor would help to get the engine tuned at its higher efficiency, but it wouldn't be unsuitable to an automotive application because the supercharger is enought to push the regurgitated admission charge back to the cylinders.

Been off here a few days for school and reorganization of ideas. Good news is that I passed both of my fast track courses, so I have one class between me and graduation in May :thumbup:

Adam728 - I appreciate the brute honesty! Seriously, I was getting frustrated trying to figure out how to make this junk work. I've been going back through and designing this motor from the ground up, planning on building a motor similar to what you have listed.

- 350 block, bored .030 over (355)

- ported and polished 193 TBI heads. Polish the combustion chamber and increase the cc's to 66-67 for all. This will reduce the chances of one cylinder being knock prone. Also, exhaust will be ported and polished. Z28 springs, screw in studs, 1.5 rockers int./1.5 or 1.6 rocker exht.

- Flat top pistons with 4 valve reliefs, +6cc tops

- Stock crank and stock rods

- 0.039 squish/quench

- 08-525-8 Comp Cams Tri-Power Extreme roller cam, 116* LSA, 194/206 @ 0.050" duration, .470/.464 lift, 800-5000 powerband

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1550&sb=2"]http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1550&sb=2

- Static Compression Ratio of 10.04

- Dynamic Compression Ratio of 8.25

- Possibly TPI EFI :D Found some sets around here for less than $500. If not, TBI EFI.

- 1.5" primary headers, ceramic coated, with 2.5" collectors into 2.5" duals. Y those together into a 2.5-3" single out the back with a good flowing muffler.

I'm thinking that I will take this project slowly and take my time with this build so that it will be the best possible when the motor is bolted in.

As far as exhaust piping is concerned, would a single 2.5" or single 3" be better? Pros & Cons??

Elhigh -

I'm taking your wisdom and using it! You are right, TBI isn't well suited for an Atkinson motor.

"You're truck is an aero disaster." made me LOL. I have thoughts of a partial grill block, undertray, and a bigger air dam. MAYBE an AeroCap as BigDave mentioned.

I think a chassis tune would be beneficial to my truck. Setting up bearings correctly, alignment, fixing brake drag, could all add up to 5%. A 5% increase from 15 is 15.75 mpg. An increase none the less!

I was going for awesome and sexy... it seemed viable and not too too complicated. I still have plans for a Atkinson/Miller cycle LS1 :D

BigDave -

You bring up an excellent point. GM surely knew what Crower was doing less than 10 years before and rejected it for good reasons.

The manual may not be long-term. I have to rebuild my 700r4 and it will take over $800. For less money, I can buy a used NV3500 will most of the components :thumbup: Do you think the NV3500 will handle the K5? I'm also on the lookout for higher gears/ high geared axles. To be honest, I was planning on putting in 4.56 R&P. Why so deep? Because @ 50 mph (my usual cruising speed) with 32" tires and in 5th gear, I'd be turning ~1750 rpm. This is on the lowside of the efficiency rpms for a 350. @ 65 mph, my rpms would be 2272. Which is not super bad for my aero and weight.

Could 3.23 gears cause lugging? @ 50 mph in 5th with a 32" tire, the rpms are 1238. Remember that lean burn cruise is planned and that can change everything.

BTW, a future project of mine is a 1985 C10 2wd with 3.08 in the rear :D I would like to keep it a 350 gas because it was my granddaddy's pickup (deceased now). I have played with the idea of a LS1 with the Atkinson cycle and a 5-6 speed manual and a suspension slam. At 1/2 your size (3500-3800 pounds) and better aero, it will be the gas truck to top 30 mpg :cool: just have to get there first! A man can dream, right?

Found this sweet gem of a deal last night :D

http:// http://raleigh.craigslist.or...896240943.html

I will be going tomorrow and inspecting his setup. If it checks out, the K5 is going TPI! And I'll be selling my TBI setup!

Dunno how hard core you want to get about MPG, but my experience is that running at LOW rpms gives better mpg even if below the "efficiency peak rpm". But instead of getting lower gears and bigger tires, you can just get SMALLER tires. Again this would be a hard-core mpg play, not a "bad-ass looking truck" play, but smaller tires would also lower it and reduce aerodynamic drag.

Speaking of aero drag, depending on how much driving you'll do at highway speed, that is what will yield your biggest results (assuming the new engine runs well). And by "running well", I mean stock re-build - nothing fancy or exotic. You mentioned a bigger air dam. YES. take it down to the same height above the ground as the lowest hanging stuff under the car. Grille block: again YES. I got 2 mpg just from that. Block off as much as you can & not overheat. You might be surprised and be able to block almost all of it! Looking at your side mirrors.... again, for hard-core mpg and "screw the looks", how about getting some really small car mirrors on there? Then finally, build some sort of lightweight Kamm-back or boattail.

I know you are all into your engine mod ideas, but my experience is that as long as the engine doesn't run like crap and waste lots of gas because of that, the bigger gains will be from aero and hypermiling techniques. Of course, do the lightweight synthetic oil and remove all unneeded parasites running off the fan belt (and the fan itself, probably - replace with an electric one). And same thing with lightweight synthetic gear lube in the differentials, too. - and keep the tires aired-up to max sidewall or above.

Simple things like that will, I'm guessing, add up to more mpg improvement than the most exotic specially engineered high-efficiency engine would. :thumbup:

I'm reminded of MetroMPG's story (I think) about a 1st generation Honda Insight hybrid he got. Thing is - the battery pack was shot & he didn't want to buy a new one, so just disconnected all the hybrid-related stuff and got like 100 mpg out of it as a conventional gas car!!! See, it wasn't the exotic engine (hybrid system) that made the 1st generation Insight so great (although it helped - some), but instead, it was overall shape, size, and design of the car itself. I'll bet you could transplant just about any similar sized, modern efficiency gas engine into a 1st generation Insight and still get stunning mpg with it just because of the CAR, not the engine. So I say if mpg is your main goal, don't put so much effort into the engine, but instead, somewhere it'll REALLY help - like a boattail, air dam, grille block, etc, etc... ;)

GM made V6 blazers in the 80s. They were gutless and got almost the same fuel mileage at their V8 counter parts.
Only time they gave any benefit was unloaded on flat ground, where you wouldn't miss the power it should have and where the V6 is all you really needed.

Now if you had a turbodiesel 6.5L V8 and if it only got 20mpg then you would some kind of problem with the engine, or a fuel leak or 2 some where.