I'm wondering what you guys think of this for making ok power and getting good mileage, also i'm wondering if i'll have to do any computer modifications, i'm assuming the computer will be fine

I'm not building this till the summer at the soonest but my ta is my summer daily driver

I'm going to clean up a 92 Van 350 with 1 piece rear main and 2 bolt mains that i have sitting around

this is the rotating assembly
http://www.summitracing.com/parts/ESP-B13402L04053/
simple cast crank i beams and aluminum pistons

http://www.summitracing.com/parts/CRN-104221/
compucam-I'm not sure if I should get 1.6 or 1.5 rockers the extra lift might be unnecessary

http://www.summitracing.com/parts/AFR-0919/
i'm kinda doubting i need more than the 180cc

http://www.summitracing.com/parts/TFS-30494060-040/
head gasket-shooting for over 10:1 compression but not over 10.5

and then the edlebrock tpi manifold
http://www.summitracing.com/parts/EDL-3860/
http://www.summitracing.com/parts/EDL-3865/?rtype=10
I have the slp runners but i don't really like how they look

I didn't find any vortec style heads on first glance that would give me the compression i want with flat top pistons but if there is a set I'll upgrade to the edlebrock vortec base with ought question

any suggestions will be appreciated

 

Compression is WAY WAY WAY low (will end up right around 8:1)

Cam is WAY weenie (only 2° more duration than your stocker, might as well not even bother)

Why bother with a 350, if you're buying a crank, rods, & pistons ANYWAY? You're walking away from 30 FREE cubic inches, which is about 30 MORE FREE HP, on the table. Not a very bright decision.

No comment on the rest, I'm not an "expert" on the various TPI replacement parts. I avoid them. Too much $$$, doesn't fix the basic problem (the "T" in "TPI"). If it was me I'd ditch TPI altogether and put a MiniRam on it, since you're in the Chicago area I doubt there are any emissions-related issues with you doing the same. Won't cost very much different, is probably worth 75 FREE HP to this build.

I'd suggest flat-top pistons WITH THE BLOCK ZERO-DECKED TO THEM (VERY IMPORTANT), 64cc heads, Comp "502" cam http://www.summitracing.com/parts/CCA-08-502-8/ ; "503" http://www.summitracing.com/parts/CCA-08-503-8/ and Bosch 24 lb/hr injectors if you go with the MiniRam.

Did I mention, that by spending your money more wisely, you can get a good solid 100 HP MORE than your current plan, for the same $$$$? Does that appeal to you?

 

Wow - that's $3 grand! And just the large parts - figure another $500 for junk/misc. Could easily do an LSx swap for $3.5k! Can't imagine what you've got there would be better than an LSx swap.

 

Eh, maybe but probably not depends on what you get then you have to go thru and wire everything up/etc. May not be an easy task in the end.

If you run one of the 86-89 MAF systems, it may be ok with mild mods but you will need tuning to get the most out of it and drive smoothly. MAF can tolerate alot of mods for general driveability but idle could be abit choppy and WOT tuning be way off optimal.

 

yes I will be getting the block cleaned bored and decked

as I said i'd like it to get better gas mileage not more power, i'd rather have lift than duration

AND i'd like it to look stock, otherwise i'd just get a junkyard vortec 350 from a truck with the comp/wiring harness
BUT i'd also only like to do this ONCE to this car i'm never planning on switching out its engine again

 

If you don't want more power, you don't need to spend $1200-1500 EACH on aftermarket heads and intake replacements, and another $850 or so on cranks, rods, & pistons; and you don't need more lift. You're going in the entirely wrong direction.

"Decked" is not the same as "zero decked". Zero-decking means measuring the exact "height" of the rotating assembly, and decking the block by that exact amount, such that the new pistons come to exactly flush with the deck. In a stock block, the block has an extra .025" or thereabouts of deck clearance (meaning, the pistons are .025" "down in the hole" at TDC), which DRASTICALLY lowers the compression. Worse still, in a stock block, the factory's QC tolerance on that is TERRIBLE; there is almost never less than .025" of this, but on a given block, it can easily vary by .010" or more from one side to the other and/or from front to rear on one side. This is one of about a million reasons why 2 supposedly "identical" cars can run SO different. VERY FEW machine shops of the corner parts store variety are capable of this; it's mostly a racing kind of thing.

However all that may be, if all you want is better gas mileage, you won't get that by swapping out parts, regardless. The means to that end is TUNING. Which of course means, computer modifications, in the software area. Burn your own chips. Off-the-shelf ones (Hypertech, Jet, etc.) or mail-order tunes no matter how skillful the tuner, are UTTERLY WORTHLESS.

Best path to gas mileage is to forget about buying ANY of that stuff you mentioned. Put your L98 heads on your van short block. Leave the weenie TBI cam in it. Put your stock runners and base on it. Then get the stuff it takes to tune it, which could take any of several forms, and go to work. Visit the DIY Prom board on this site for guidance.

 

Dont know if I read this wrong but the heads are 1464 a pair on summits site, not per each. Not sure if you were refering to 1500 for heads and 1500 for intake parts...because all the TPI parts will add up to a grand

But I agree everywhere else, if you are not interested in power, then just rebuild your block with a budget rotating assembly but make sure you have quality machine work done. Throw the TPI back on it, throw in a mild cam if you cant find a stocker, and recondition a set of L98 iron heads. Have them cleaned up, valve job and new springs with screw in rocker studs.

Tune that setup well and you could get over 25mpg. My exhaust modded L98 with no tuning ran 24mpg on highway with 2.77 gears...I am confident you'd see an improvement with tuning.

Now if you want abit more power than a stock build and gas mileage, do what you wanted on stock reconditioned heads and throw in the mild cam thats only a few degrees more than stock with bunch more lift but keep it below or at .500". Bolt on aftermarket TPI stuff and you should beable to have a solid 275whp with a good tune and get very good mileage. Thats low low 13's to high 12's all day long if you had 2800 stall and 3.42 gears on good slicks and great track conditions.

 

Exactly how much power and mileage are you looking for?
Why aren't you considering factory TPI intake parts? or what you already have?

 

I have no idea what heads I have, I was looking at aftermarket because I was under the impression that the tpi base doesn't have the same bolt pattern as the carburated intakes (all i have are carb heads except whats on there now)

I should have asked for more opinions on the numbers... the parts were essentially irrelevant...

I was interested in an aluminum head, I currently have cast Iron.. I also have a 1971 LT-1 shortblock as my signature says... so I have forged steel pistons/crank/rods its all adding more rotational mass than i need... the rotating assembly I linked has aluminum pistons and a cast crank (crank may weigh about the same)
I also do not have a 1 piece rear main crank or flat top pistons to use

I also do not have a TBI cam to use I have a mild cam currently that gives me a fairly rough idle (no idea on the specifics)
and I certainly can't take apart my S-10 for the solid roller in there that would never work with the computer

a short duration cam is what I wanted and the 116 LSA supposedly also helps, looking for as little overlap as possible if you guys have any other cams I missed I'd appreciate the help also a roller cam would be preferred

if you know where there are some cheeper 64cc, 65cc chamber heads with stock to 2.02 intake 1.6 exhaust valves, If you know of some vortec heads that fit the bill that would be best

If i'm completely wrong and 10:1 compression and a low overlap cam wont give me fair mileage (25-30 would be nice) than point me in the right direction? this is just a plan i'm not buying anything until june

this engine is going in the back of my garage until I feel like building a nitro motor for my S-10 I'm using this van block I received from a friend for free to build a nice daily drivable engine for my Ta

also i should mention the junkyards around me (there are only 2 that i've seen worth going to) they have almost only small cars there are NO F-bodies no corvettes few trucks no V8's to spot unless its an old cabbie crown vic if you need a part for a civic a ranger or a grand prix you're set I have to drive 50+ miles to get to another junk yard worth going to and i'd rather spend the money on a new part than take the trip

I'm sorry my original post left too many questions I hope this will help you help me?

 

thats essentially the plan though it'll never go to the track except on car show days

 

So does everybody else.

There's about 1000 times as many "LT-1" short blocks running around these days, as there were Vettes with the "LT-1" badges on the hood plus the "Z/28"s that came with them. The term is bandied about so much as to be utterly meaningless. Furthermore, even if it WAS an actual "LT-1" short block, the odds of it being STOCK, are so close to zero that the possibility might as well be ignored.

It makes not the slightest difference whether your crank is cast or forged, as long as TPI is on top of it. Any crank is equally valid, and equally useable (or not) for a gas mileage goal. Likewise, there are about a billion forged pistons on the market; most often when people say that without further qualification, they mean TRW/SpeedPro "rebuilder" ones, such as the good old L2256, that we've all been using for "budget" builds since forever.

Pistons are pretty much ALL aluminum. Forged cranks and cast cranks weigh about the same (expect 52 lbs ± 2 lbs). You're barking up the wrong tree if you think you're going to get $850 worth of improvement in that area by changing that out. Altogether misguided.

You CANNOT POSSIBLY know your true compression ratio without knowing WHAT'S ACTUALLY IN THE MOTOR, and what machine work was done to it. For example, you could build a .030" over 350 with typical "rebuilder" pistons, including TRW/SpeedPro forged, most hypereutectics, and virtually ALL cast ones, like most people do. Those all have about 6cc valve reliefs, and an extra .020" of deck clearance on top of the stock .025" or so, meaning that without machine work to correct it, the pistons would be at least .045" shy of reaching the top of the block at TDC, give or take (factory production tolerances are NOTORIOUSLY sloppy in this area). The end result is, if you built such a short block, used typical head gaskets such as 7733PT2 which are .039" thick, and 64cc heads, you would end up with a compression ratio in the low 9s; somewhere around 9.2:1. OTOH, if you used racing flat-tops, with a typical 4cc or so in a single set, not double, of valve reliefs, didn't have the "rebuilder" .020" of extra deck clearance, and had the block zero-decked to the rotating assembly, and then used the same heads and gasket, your CR would be in the 10.3 - 10.4:1 range. Because there is SO MUCH variation in THE DETAILS of what parts were used and how the engine was built, it is impossible to ACCURATELY calculate the CR of most motors. We certainly don't have enough info about yours to do that.

Bottom line, you are in the "measure with micrometer, mark with chalk, cut with axe" situation with your existing engine's CR. The potential variability in it is SO VAST that it's beyond pointless to try to pin it down to closer than within about a full point (although, odds are, you're at or near the bottom end of the possible range, like the majority of other motors that have been rebuilt). Therefore there's not alot of sense in trying to outsmart yourself regarding that particular factor.

But if you don't use that motor for this project, then what it is exactly, doesn't too much matter; let's just leave that aside, and you can deal with that on down the road whenever you do whatever else you're going to do with however much of that motor is re-useable.

The heads that came on TPI motors have the same bolt pattern for the intake as the heads that came on carbed motors, year for year. In fact the same head castings were used for TPI 305s and carbed 305s, year for year (416 in 85 & 86, 081 87-up). The only exception being, the heads that came on the Vette L98 with the aluminum heads, has the 86-back bolt pattern instead of the 87-up bolt pattern. TPI itself is identical in every way between 305 and 350, year for year, except for Vettes from 87 up which have a different EGR arrangement. Therefore the heads that came on 350s were the same bolt pattern as the ones on 305s, year for year; and the same heads that came on TPI 305s were on carbed 305s, year for year; therefore the bolt pattern on 350 TPI heads is hte same as the pattern on any other heads, year for year.

Vortec heads DO have a different pattern; not only the bolt holes, but also, FAR MORE IMPORTANTLY, the intake ports are in a different place. Your existing TPI intake probably won't even COVER them completely, let alone match to them. There is an aftermarket base that you can buy which has the right pattern but it is $$$$, and most people who have used it report disappointing results. If you intend to keep TPI, Vortec heads are probably not the way to go.

Aluminum heads REQUIRE nearly a full point of CR higher than iron heads TO MAKE THE SAME POWER, because they "leak" so much more heat (energy) out of the chamber, and away from the power-production process. Meaning, to get the same power as a 10.3:1 iron-head motor, you'd have to build about 11:1 with aluminum heads. There's nothing about your stated goals that says, "heads must be aluminum", technically. I'd keep my money in my poscket on that one, if I was you.

A stock L98 in one of these cars will run mid 14s; 14.4 - 14.8 being fairly typical. So, enumerating the differences between what you do/will have and comparing them one at a time to stock:

Your CR is lower than stock. Your car will run slower. How much? who knows.

Your heads have had some port work done to them. Your car will probably run faster. How much? who knows.

If you put a "mild" cam in it, close to stock, your car will run .... close to stock. How much different? who knows. Probably, not a whole lot.

Sounds to me, if you do what we're talking about, you'll run just about the same as stock. Expect mid 14s. Low 13s is a pipe dream, let alone 12s.

Not sure what 2.02" valves have to do with any of this? You can graunch those into ANY heads, stock or otherwise. If you want, you can jam them into your L98 heads. Any machine shop can do that. Won't make a damn bit of difference to the end result though; because THAT'S NOT WHERE THE RESTRICTION IS, in a TPI setup. It's money basically down the drain.

As I see it, for your stated goals, you already have everything you need. Rebuild your van short block if it needs it; set the existing one aside. Spend your money on MACHINE WORK, specifically zero-decking the block, which has a payoff; all the rest of that stuff you're talking about buying DOESN'T get you closer to your goal. Use the stock van crank and van rods, TPI will protect them from ever seeing any stress beyond their design limits. If the block needs to be bored, get GOOD pistons; specifically, ones that DON'T have the extra .020" of deck clearance. Have the crank index-ground, the rods sized to equal length, and the block zero-decked TO THE RESULT. Use your stock TPI heads. The only junkyard type thing you may not have that you'll benefit from getting, is the factory roller apparatus to go in your van block; you can get all that from a 96-2000 Chevy/GMC truck (no need to worry about F-bodies and Vettes in your local junkyrads). Use the Comp "502" cam I posted above. That combo will be faster than a stock L98 (probably not by much, but it'll be at the fast end of the "normal" scale), as reliable as any stock motor, and cost you thousands less than what you originally proposed.

But none of that will have any material effect on gas mileage. For that, you need TUNING. Nothing else will do. If that's genuinely important to you, you will either learn to write spark & fuel tables and burn PROMs, or you will take some of the THOUSANDS you DIDN'T spend on all that romantic-sounding hot-rod stuff you DIDN'T buy, and use it to buy some one of the available aftermarket tuning setups. Those might include EBL, an aftermarket ECM, or some other approach; you'll have to be the judge of that. Don't argue about "but... but... it's a computer, it's scary, I don't know how, I can't, ...." If that's GENUINELY IMPORTANT to you, and not just a bunch of running off at the mouth, YOU WILL DO WHAT IT TAKES.

I think once you dive in and start un-learning all the hot-rod superstition and mythology that whoever you've been spending your time with has infected you with, and LEARN what you're doing and what REALLY works and what doesn't, you'll find that it's not NEAR as hard or expensive to get where you want to go, as long as you keep your goals realistic. 12s with TPI and 25 mpg is NOT realistic, unless a bunch of nitrous is involved. Low 14s, yes; 12s, not so much.

Remember: the main thing is to keep the main thing, the main thing.

 

Agree with the write up, especially what I quoted. I started off thinking bolt ons would help me achieve my goal, with used "opportunity" parts. No way of forecasting what you'll end up with unless you know how part tolerances/measurements interact.

 

I would quote all of that but its a waste of my time...

this is also incorrect.. in 87 the bolt pattern changed... and my pile of parts from older style carbureted heads (as i said before) would not work with an L98 intake so I'm not sure what you're getting at there?

I'm also a little confused why you spent all that time complaining about my current engine? I really don't care about it and i'm not sure why you'd like to waste your time arguing with me about it?

not to mention you seem to have a hard time with numbers? that crank is $596.95 you keep saying 850? I'm a little confused.. kinda like how you said my heads would be 1500 each...when it was $1,464.95 for the pair? I need correct information to make a good decision...

I'm building a NEW motor from NEW parts (aside from the block) that is all that matters..... I'm not broke I can afford a 4k motor and i'd prefer to build it myself... crate motors are not as interesting I gave you my goals... rather than sending me essays unrelated to them... how about linking me parts or information to achieve my goal...

thank you Orr89RocZ for the help so far

 

The bolt pattern is the same
Put a intake gasket on your parts and see IF there is a difference!
The angle of the 4 center bolts in the '87+ cast iron heads changed from 90 degrees to 72 degrees.
Easily solved by elongating those 4 holes in the intake to fit late style intake on early style head
or vise versa
Only Vortec and LTX heads have different bolt pattern

 

personally I feel forcing it to fit is a bad way to go about things... I know people who have done it... I wouldn't.... I'd like to keep it reliable and show worthy

 

No forcing involved .
The intake is a perfect fit to heads and block; only the angle of said bolts is different
Many of the aftermarket intakes like the HSR and MR come with the center holes slotted so
the one intake fits both style heads ; early or late

How does a elongated hole like this make it any less show worthy?

 

its the other side that counts, again I've seen other people do it theirs never looked right... I opted to just buy tpi heads and rebuild them (this was on my S10 when it had a computer) rather than try to elongate the holes

THAT intake looks absolutely perfect though I could never make it that clean, the few guys that i know that did it for their off roaders... look terrible... If I tried it would probably end up messy aswell

 

When I quoted $$$$ numbers, I was being approximate... $1500 each for inatke upgrades and head upgrades, not $1500 each for a head... sorry for the confusion... you're proposing $1500 for a pair of heads (they'll be more than that with shipping) you don't need, $1200 for various intake upgrades you don't need, a crank you don't need (shipping on a crank is also significant $$$$)... don't just look at the numbers in the catalog and assume that you're done at that point.

As far as the heads: Everything I told you is accurate. EVERY WORD. As I told you, 86-back uses the original bolt pattern, 87-up uses the late-model one with the 2 center intake holes angled differently, and there's no difference between "carb" heads and "TPI" heads, in the same year. Not sure what part of reality you have a difference with?

It's EXTREMELY easy to convert the year-model difference. You could either convert the heads by plugging and re-drilling, or elongate the holes in the intake. Either would cost AHELLUVALOT less than buying new heads just to get the other bolt pattern. Not sure why you'd have to do either, though; you're going to be using YOUR TPI intake from YOUR L98, with YOUR L98 heads, so it should all bolt right up; eh?? But regardless, even if you can't do it neatly by yourself, it's still DIRT CHEEEP to pay somebody to do it; AHELLUVALOT cheaper than buying new heads.

I'm trying to help you NOT spend HUGE UNNECESSARY giga$$$$ on stuff you don't need. I can't "link" you to the parts you have sitting in your garage.

However, maybe I assumed too much; fpr some reason I seemed to be under the impression that you were currently running your stock L98 heads, P&Ped. Maybe that's been edited out somewhere along the line?

Maybe a good thing to do would be to identify what heads you currently have. Maybe they're trash (TBI heads or something); maybe they're the stock L98 ones. If they're the stockers, clean em up and re-use em. For your stated goals (daily driver, little to no strip time, "show" whatever that means has crept into here somehow lately, better gas mileage than stock, more power than stock not required) there's just no need for anything else. If that's what you've got. What is their casting #?

I have a hard time believing that about junkyards. I was just up there a couple of weeks ago doing some work at a place on Farnsworth in Aurora. Saw a couple while I was passing through. I'm originally from Chicago in fact although I haven't lived there since the mid 60s. I've actually driven up there in times past (to the Gurnee Mills area specifically) to buy junk F-body parts. So they're there, I know. Put forth a little effort.

I cannot emphasize strongly enough, that there is no technical reason to spend all that money to achieve your stated goals. You say you want to buy new parts, but there ARE NO new parts that are any better than your stockers, for accomplishing what you say you want to accomplish. Your van short block with its stock internals (no $$$ crank kit), your stock TPI heads (no $1500 AFRs or whatever the TF ones you edited in there go for), no $1000 aftermarket intake parts, just some machine work, cleanup, a new cam (which I LINKED for you, I spared you even that tiny little bit of effort of looking it up), and some junk out of a truck. That's all you need to get where you want to go.

LISTEN instead of arguing. You're headed for disappointment, as your "plan" sits. It WILL NOT WORK like you say you want it to. You're badly misinformed, and your "plans" don't match your "goals". No matter what each one is, lack of a match is a GUARANTEE of a failure. I'm trying to help you see where they misalign, and fix it.

 

Is that a little extra space around the center bolts there?
Oh, I'm sorry but you're not getting best of show today. Not on my watch.
Perhaps you will do better if you come back next year with a correct year factory intake base, ...

Sorry, I couldn't resist.

I know this is flip, but I'm going to have to say that if someone can't drill four holes straight, yet their going to build a performance engine, there might be more to worry about here than some extra space around some bolt holes. I don't know, but I hope I'm understanding this wrong.

Bolt holes can be spot-faced and/or countersunk on a drill-press in a machine shop (or your garage) in about 5 minutes. Then your choice of washers will effectively cover the extra space.

The OP said " any suggestions would be appreciated."
It doesn't seem to be working out that way though.

 

thats not a suggestion for what I was asking... I didn't ask how to save money I asked if the combination of parts would do what I wanted I also said I wasn't buying those parts specifically if you read everything...

 

sofakingdom you continue to disappoint me... I don't care to argue with you... before I have to read another long response please answer me these questions directly before i'll take your essays with more than a grain of salt...

1. is a higher compression ratio... like 10:1 offer more effective combustion in a reciprocating engine?

2. is a low or high amount of overlap in a cam desired for limiting wasted fuel/ maximizing fuel efficiency

that first response you gave me was the closest to what I was looking for that you've given me though it was in the opposite direction, I had linked the head with 75cc chambers rather than the 65cc i'd indented you corrected me... giving me cam's you'd suggest for more power (which I do fully agree with) though that doesn't appeal to my intentions

you've argued the amount that i'm willing to spend when cost was never in question
you've also argued the components of a mystery engine that I've only guessed the contents of based on how it drives/appears...

I'm not building an engine based on guesswork... I'm not bolting on a frankenstien assortment of parts ether... I'm getting mostly new parts and I'm planning far in advance what will work together to get the closest to the desires I have

since you're so curious...
I have bosch #3 injectors (It seems), a holley AFPR and an MSD big cap dist with a 6A box as well as SLP runners those are the modifications I'm fairly certain have been done
I put on...
MSD 8.5mm wires and NGK iridium spark plugs (it had un-cut 8mm wires and champion plugs) those two changes made an enormous difference to its performance/drive ability... I don't believe the champions even had the right spark plug gap...

I'll give you an example of how I feel about this car maybe you'll understand what i'm doing with the engine...
one of my rear break pads wore out so... I replaced all 4 rotors and break pads all around along with installing new bearings in the front...

because I did this I found out the passenger side wheel bearing was destroyed, the rear break line was rusted/leaking, the rear passenger side caliper was seized and the master cylinder/ break fluid was dead
I'd rather replace everything at once than have something break on me since I don't know how old anything is...

the U pull it aurora has 1 2.8L 1990 camaro with almost nothing remaining of it... first F body I have seen there in 4 years they remove any half decent engine/transmissions as well as overcharge for what they leave they also refused to tell me what they had or pull for me on more than one occasion even though I had the money in hand...

the other large junkyard has an online catalog of their parts http://www.cityautowreckers.com/

the "farnsworth" junkyard you referred to i'm going to assume is Valley auto wreckers and they had a firebird with little but a nicely painted hood left everything was removed when they got it, they have a tendency to crush the wrong things far too soon I was lucky to get a transmission for my S10 there, I'd recommend buying from them if you're stuck in the area they are very fair

I have heard of some very nice junkyards in Gurnee Mills but as I said... thats about 50 miles away

I apologize for myself going so far off topic...

 

All I'm doing, is being logical, and carefully proving, and backing up, what I'm telling you. Sorry if that offends you.

All that crap about 4 brake pads is irrelevant. Willingness to spend money, while a worthwhile attitude in this hobby, is not automatically the same thing as spending money RIGHT. In your case, EVERY suggestion you have made as to how you're going to spend all this money, is BACKWARDS to accomplishing your stated goals. You don't need to spend money on castings to reach your goal; any money you spend that way, TAKES YOU FARTHER from it. The thing you DO need to spend money on, TUNING, you steadfastly refuse to acknowledge even the EXISTENCE of. You're headed for failure.

Sounds like instead of help or advice or learning, you want an audience to applaud you.

Which is perfectly OK with me. It'll just have to be some other audience.

Bye.

Good luck!!!

 

How bout we ask the question, "what kind of gas mileage are you trying to achieve?" since you say mileage is more important than power.

Once we have a target that you would be satisfied with, lets try to make the most powerful combination of parts that will still net that mileage so you get the best of both worlds.

My L98 with factory tune but with headers/exhaust and gutted air intake box would do 24-25 mpg highway. ran very high 13's on slicks with 2800 stall.

My 383 I would be confident it would hit 20-23mpg highway as well but I never checked mileage...and it ran 11.4's on motor.

My friends 406 runs mid 10's ON MOTOR with a 6 speed and got around 20mpg highway. It all depends on your target, and tuning.


In my opinion, you want less overlap to minimize EGR effect at idle and low rpms. This also keeps cylinder pressure higher during cruise, make more torque to move the car. Should increase mileage as air/fuel charge wont be blown out the exhaust valve. The more efficient motors today have decent compression and low overlap cams.

I also think higher compression helps since you should beable to extract more energy out of a given fuel charge with a higher compression ratio. There are limitations, you cant have 15 to 1 comp with a 206 deg cam and expect it to run on pump gas Need to balance out the cam events with the compression ratio in the rpm ranges you will use for gas mileage cruising, but still beable to make power in the higher rpm ranges. This is where variable valve timing is key, but we dont have.

 

THANK YOU again for actually answering my questions and giving me useful experience...

I'm looking for around 25 mpg at 65 mph (i'm at about 1500 rpm at 55 now with the 700r4) maybe in 2012 I'll swap in a T56

the pump gas issue is why I was thinking around 10:1 would work well
I'm not expecting to rev it over 4k very often (if ever)

my thinking is that I'll want to take this car to shows in 20 years and DRIVE IT... I'd rather not need to rebuild the motor then ether... as LS motors become more popular and old gen 1's loose their popularity making parts harder to find and more expensive, not to mention none of us want to think of what gas prices may be in 20 years... its a theory but at least gas prices will definitely be insane warranting my mileage over power decision


now the heads I have whether they are L98 heads or not they are badly ported (at least from what I could tell on the exhaust when I was replacing gaskets)
are there any aluminum heads with a similar runners/chamber/valves to a stock L98 I should be looking for?
from what I remember its 165cc runners 72cc chambers and 1.94int/1.5exh but I'm not sure

I remember in my search someone claimed to get great! mileage (27 mpg highway) with the afr 195's in a 383 (didn't mention cam) and the same trans/rear as me, though if he's an amazing tuner it could happen? I'm assuming its not entierly true

 

Ok with 25mpg in mind, tuning will obviously be the key but certainly doable while making good hp. Now it just depends on how much you want to spend and how much of a challenge you want to take on with regards to tuning. When it comes to the amount of time spent on tuning, I think a wilder combo will be much harder to get good mileage out of than a milder combo. Some motors can be picky with fuel requirements, some not so much.

I dont have much experience tuning for mileage...most of the builds i've helped tune and including my own have been with max power in mind. The 383 I had did get impressive mileage but since I never calculated it I cant be certain it was impressive..but it certainly felt reasonable for the power I had. It was a great driving car but I kept that tank at 1/4 tank and not much more to keep weight down at all times. I could go a good while without having to fill up tho.

Well stock 113 castings from a vette are basically aluminum version of our iron heads except slightly smaller chamber for more compression. They are the same head basically as what comes on the ZZ4 crate motors however GM sells the ZZ4 heads at ridiculous prices. Summit has 170cc heads, trickflow has 175 cc heads, AFR/DART/BRODIX has 180's, and some others I believe.

Things you need to look at for driving status for 10+ years and many thousands of miles without a rebuild....
- need quality machine work to the block and rotating assembly. Good clearance tolerances and well balanced assembly will give long life. Doesnt need to be forged everything since factory cast motors have lasted long time. My 89 L98 was 160K miles and ran high 12's with bolt ons... probably as strong as the day it left the factory.
-- camshaft design with lobes that are not too aggressive to beat up springs. This means less aggressive ramp rates and lower lift in general but a custom grind could be considered. Your looking for valvetrain endurance here. Dont skip out on good quality valvesprings too, more money but well worth it. Beehives would be a good choice as newer LSx motors have them and last a long while. Even the newer small diameter double springs seem to show good life.
-- good maintenance over its life time. That is common sense.

Stuff like that will make for a good quality reliable long term service.

Now its up to you to decide if you are ok with a stock rebuilt motor and tuned for 25mpg or if you want to try a mild heads/cam package with some extra hp and still tune for 25mpg. I think it can be done. It requires a light foot, and tall highway gearing but should be possible.
You just dont see alot of results posted about MPG and performance engines and since I dont any real data other than what my bolt on L98 did, I cant really say for a fact that combo X will give Y mpg and Z hp.

 

its not going to be driven too often (only in the summer) I wouldn't expect too much more than 3k miles per year but durability is why i'm looking at a roller cam probably with steel roller rockers then with lsx beehives?

http://www.summitracing.com/parts/EDL-60979/ this is a vortec style intake I didn't see much in terms of the 87+ bolt pattern or older pattern
but is this more what i'm looking for?

 

I may not use the TBI 350 after all this just showed up in one of the junkyards near me
http://www.cityautowreckers.com/cgi-bin/search.cgi

I'll go there on sat and see what they want for just the block

 

Well you can use the edelbrock vortec heads but they arent anything special for the price, might as well just use truck take-offs and freshen them up or go to scoggin dickey. if you wanted aluminum i'd stick to convential head in the 170-180 cc range for mild bolt on power with mild cam thats easy to tune and get great mileage. Summit 170's aint bad I guess but for the price you probably could get away with a mild cleaned up L98 aluminum vette head.

I really like the 180cc heads from AFR or Dart or even the brodix IK180's. Good heads for the money and would compliment a nice mild cammed 350 well. IK180's are tough to beat for a mild setup

 

alright then http://www.summitracing.com/parts/BRO-1021004/ for my standard intake? I'll keep looking around to see if when the time comes there is a set of 170cc heads available?
If I remember right the D ports wont make a difference so long as my headders are big enough for them?

and I'll see how the heads that are on this block look, if they let me buy parts of it rather than the whole thing that is