I finally got a real hot rod again, so I am putting the iroc back to daily driver status.

I am going to build a new longblock and want the best drivability/ milage, with some performance.

My thoughts are;

355" 9.5:1 compression

Aftermarket vortec heads

Ported vortec base

HOT cam

Headers and catback.

Engine will be backed by a rebuilt WC T-5 and 3.23 gears.


What do you guys think?

 

I keep hearing vortec is the way to go, but I keep crunching the numbers, and it just seems to expensive.

I can got with a set of Aluminum "jegs" brand 180cc heads, and would end up with much less cost involved.

The difference would be, vortec requires the $500 edelbrock intake,

where as the aluminum heads require a pre 86 lower intake, which I can get off ebay for $100.

Either one would need some port work.

 

There is always going to be a trade off between performance and mileage. To make horsepower it needs more air and fuel. That being said I'm going off the idea you want something 1/2 way mild for the street but not a total turd.

Have you seen some of the crate motors offered lately in JEGs and Summit? Basically $3000-$4000 gets you 350+ HP and some have warranties even (2 years+ or 50k miles). Those might be good a choice depending on what your goals are for a daily driver.

 

Of course there is always a comprimise. With this one the goal is really daily dravablility/milage, but I would like it to be able to get aout of its own way.

300hp at the flywheel would probably be a reasonable goal.

Bad thing about the crate motors is the cams are usually not the best for a TPI set up.

I had a back experince with a crate motor last year and will not buy another (read the fine print on those warrenties)

I will build the engine for this, the big question at this time is the heads.

 

Are you opposed to throwing in an LT1? You could even drill the intake and run a distributor to avoid the opti spark.

 

I don't think it would be cost effective.

I have a complete tpi system already. LT1 swap would increase cost, and I don't think it would be that much better milage wise.

The big improvement on the LT1 cars that gave better milage was the extra overdrive the T-56 offered.

 

True. I was only thinking LT1 because something drop/stock with the power you wanted is easier than tuning. And motors like that generally run smoothly without the ill characteristics of certain cams.

My cammed L98/ 5 speed actually gets better mileage than my lt1 for whatever reason but is a little more involved to drive everyday than I'd like.

 

Why not just throw in a L-31? The long block is like $2k through summit and jegs plus you might be able to get free shipping. Compressions like 9.5:1, vortec heads, roller cam, and the cam while very tame is fairly aggressive for its duration. In stock applications they put out something in the upper 200s so not far from your goal. Other companies like Scoggin-Dickey even just take that motor, throw in a hotter cam, and re-sell it. Its really a solid budget motor and I it think would go pretty well with TPI.

 

Vortec heads = $500 base intake.

Not sure about the cam in the crates being TPI friendly.

As stated, had a bad experince with a crate engine and prefer to build my own.

Not looking for a hp monster, already had one of those in the car, just looking to go back to a mild daily driver engine.

 

Yea the base may be like $500 but if moneys a concern, I think you would have a hard time building a comparable motor for under $2500.

The cam is a truck cam (which is a pretty good match for what TPI is) designed to work with fuel injection.

If you want to build your own motor for whatever reason you always can. I will warn you though it's not like just ordering cranks and rods and just bolting it all together. Just take a moment and read what it takes to properly set up the valve train for the correct geometry. On the other hand I don't know who you got your last crate motor from but this isn't just any crate motor put together by some shade tree mechanic. This is a crate motor built by GM as a replacement part. If anyone knows how to put a motor together it's them.

 

Thanks for the advice.
No need for me to read how to adjust valvetrain, i built my first small block in 1993, for my 71 camaro. My 55 bel air has a solid roller big block, believe me I've adjusted my share of valves.
As for the crate motor I had, it was a 260hp 350 gm from jegs, I bought 3 years ago.
Ended up reusing the rotating assembly and heads, used a seasoned USA cast block and added a small comp cam. Went in a 1969 c10, that was my daily driver, sold it last week to buy another 71 camaro.
Cost is always a concern. I want to get the iroc back to daily driver status so I can work on the 71, it's my dd for the time being.
Thd more I think about it, the closer to a stick rebuild I want to do for the iroc.

 

going vortec?

 

Look up the Scoggin-Dickey heads. They come with both the Gen I SBC intake bolt pattern and Vortec pattern. If you talk to them they will point you in the direction of which gaskets to use to make up for the port size difference. This will let you keep your stock TPI lower for now until you can replace it later with a Vortec specific version. Their heads are also offered in various intake runner sizes, already machined for higher lift (Vortecs are limited to .470" otherwise), and feature thicker decks to prevent the cracking that stock Vortecs are prone to.

 

Maybe vortec is the way to go, as far as power.
"Ultimately, all this is in the name of power, and boy do the SDPC Vortec TPI base and heads deliver. Using a DTS water brake engine dyno, the Vortec TPI conversion twisted the needle to 305.6 hp, and that was using the stock runners, stock throttle body, a stock L98 cam, 92 octane pump gas, and 15 degrees of base timing. Calculating a 20 percent driveline loss for a 700-R4 transmission, power at the rear wheels is estimated at 244.4 hp. Next up was a combo which added an LT4 Hot Cam, 1.6 ratio roller rockers, a 52mm throttle body, and Edelbrock High Flow runners. Power swelled to 356.7 hp at a very streetable 4,900 rpm

Read more: http://www.camaroperformers.com/camaro-tech/engine/third-gen-camaro-vortec-heads-install/viewall.html#ixzz2F8AbLXGV"

I'm really curious about milage. I wonder if this type combo would do as good, better or worse then stock? Need to look through some other builds and what they are got.

 

Don't fall for that....



This is what happens when somebody thinks that drilling the bolt holes is all it takes.

 

Yeah, I knew that wasn't right.

 

Okay, lets look at this different.

MY Goal is Milage, as much as possilbe.

Horsepower goal is simple, stock or better, but no need to get crazy, I have another car for that.

Budget is not yet set, as I will spread it over a few months, but the less I spend on this the more i can spend on the 71.

The car has been lightened a bit. I have swapped over to a T-5. Will be going with a 3.23 rear gear most likely.

I will be starting with a 350 rollor block and a complete stock tpi system.

The car will have headers no cat and a 3" catback with a good muffler, not a crossflow flowmaster.

The shortblock will be rebuilt with flattops, zero decked, etc...

Comp has suggested a tiny cam, 08-500-8., .480"

I can get rebuilt 083 heads for $350.

Vortecs would be at least $600

Jegs 180cc aluminums are right at $1100.

Vortecs require a $500 base
Jegs reguire a used pre 87 base which are on ebay for $100 or less.

So, the question is in terms of efficency, would the vortecs be that far above stock and how would they compare to the jegs alumimun?

 

The SD Vortecs are made with bolt intake bolt sets, and there is a Fel-Pro conversion gasket set for using the older intakes with it. I've asked ther SD techs about this personally for the same reason. It's a stop-gap, but it allows time to save up for a Vortec dedicated base while still having a driveable car. As I said in my original post, talk to them about what you need and then decide if that's the way you want to go. I'm just pointing out the option.

 

If I was going for the best MPG/horsepower ratio, I would get a LS1 with a t56. At the very least get a t56 from a LT1 to put behind your TPI. that would help a ton on the highway.

 

http://images.search.yahoo.com/image...mb=OEjbj04A9f/

 

Too expensive of a swap.
Already have a rebuilt WCt-5 and complete TPI system.
Also want to keep the TPI appearance. Again Big hp is not a goal.

 

Once again, I recommend actually calling them, as I asked about this very issue. There is a conversion gasket from Fel-Pro that specifically is made to seal the difference between the two, and SD swears it will seal. Your other option is to buy the $400 aftermarket Vortec lower.

 

The above photo I linked is straight from their website.

 

Found these, good price, already set up for bigger cam, Making me lean more towards Vortec.

http://www.ebay.com/itm/271057279800...=p5197.c0.m619

Any reason not to go with these?

 

Update time!

I will be starting a 'build' thread for the car soo, but in the meantime, I wanted to update this.

I got some great deals on some parts, so here is what I am going with for this daily driver build.

L98 base. .030" over flattop pistons, will give me right at 9.5:1 compression

083 heads that have been cut for 2.02" 1.60" valves, overkill I know, but price was right. Already cut for larger springs too.
They will also get ported and gasket matched. Have been millled as well.

Comp 08-501-8 camshaft

Ported Lower and upper plenums.

SLP Runners, ported and matched.

 

I'll be getting an adj regulator and injectors from Southbay.

Anyone have any suggestions on injectors? Size?

 

Any update? Curious because I am in the planning stage with the same goals in mind.

 

Rotating assembly is at the machine shop getting balanced.

I'm porting the intake and heads in the evenings.

I have started a rebuild thread in the members camaros section, if you care to follow along.

 

24 lbs injectors sounds about right for your setup. That would be the biggest injector I would go with for your mods. i'm with you on keeping tpi and built for milage. I give you a big thumps up.

 

I was leaning towards 24lbs.

Thanks.

 

https://www.thirdgen.org/forums/engi...rformance.html

 

What cam are you running in your L98? Any other mods?

 

•GMPP 350 Block w/ Comp Cams 268XFI HR 13, Mahle forged flat top pistons, GM nodular iron crank, Comp 918 Beehive Springs
•Factory AC Delete
•Lowered 2 inches on Eibach Sportlines
•Full Eibach Poly bushing kit
•82 Pace Car SMC Fiberglass Hood
•Drilled and Slotted rotors
•Tuned Port Injection w/ Bosch 3 24# injectors
•Edelbrock Shorty Headers to custom 3 inch stainless exhaust w/ Hooker Aerochamber
•UMI Subframe connectors
•Hotchkis Tubular Lower Control Arms and Panhard Bar
•Oversized Eibach Swaybars and Wonderbar
•Original Black GTA Crosslace Rims

That is just what I could come up with for now. I've got 3.23 rear gears and the motor has 2500 miles on it. Averages 20mpg right now with mostly city driving, 10.5:1 comp and runs on premium.

 

Whats the performance like compared to stock?

 

The 268XFI is too big for 083 heads . Something close to the LT1 cam and not much more would work fine. You can build a 450hp TPI engine and get 25-27 miles a gallon with 30lbs injectors. Its all about the combo and tuning. I did it and so did most of us in SoCal.

 

Do you think other thirdgeners would help me to fillout this excel spreadsheet with different TPI motor combination / setups? I have seen them on the web for carburetor setups but nothing for TPIs.

 

This build is finished. Unfortunatly, it ended ip in something other than a 3rd gen.

355
10.23:1 compression
083 heads with 2.02 and 1.6 valves
comp08-501-8 cam
stock tbi intake
65lb injectors
shorty headers
stock exhaust
5 speed trans
3.42 gear

18.5 mpg so far

 

65lb injectors? How come?

 

TBI.

 

Oh yeah. Duh. I was thinking tpi.

 

MPG is all about ignition timing and a suitably lean fuel mixture.
Have you built a suitable timing curve and experimented with it? 18.5 mpg (highway) isn't very good (although I'm thinking you're still working the bugs through).
At cruise, ignition timing approaching 50 degrees BTDC isn't unreasonable with fuel mixtures around 15-16:1.
A couple of questions:
Have you done a compression test? With 10.23:1 and that little cam you should well past 200 psi cranking pressure.
Do you run a wide band O2 sensor?
Do you a full time vacuum gauge?
All essential equipment for getting the best mpg.
For what it's worth, I'm getting upwards of 20+ (US) mpg out a carbed 355 and aftermarket Vortec iron heads. Still working the timing curve and have a much too large 750 BG VS carb on it. 23 mpg is a reachable target without giving up much at the dragstrip. I had 10.4 SCR with a 274 adv cam and cranking pressure was north of 200 psi. I couldn't put any timing into it due to detonation problems. I've since opened up the chambers in the heads and went with a thicker head gasket. SCR is now 9.8:1 and cranking pressure is 185. Mileage is good and is getting better. Highway cruise at 75 mph is 2500 rpm with the converter locked.

 

Get rid of stock exhaust and get a good low profile carb dualplane intake without air gap and use TBI adapter ... I get 23-24mpg with 4.10 gears in my T-5 car and I'm not tunning for mpg I'm tunning for HP ... And run ebl flash and WBo2

Edit : quoted wrong person ... I run 2500rpm at 75mph also

91' bird 305 TBI T-5, trick flow 175 cc heads, 4.10 gears, lots of suspension upgrades......... 24mpg @ 2300rpm hwy 65mph ........ 8.63@ 85mph 1/8th on street tires... 8.000's soon

 

I have an edelbrock tbi intake and 454 tb waiting.
Big exhaust is next.

Tune is slightly rich, just a base tune to get me going for now.

I plan to do some dataloggimg and fine tuning soon.

18mpg is mixed driving, with a good bit of in town driving.

I figured 18 wasn't bad, my dads stock 1992 truck only averages 17.

I have not swapped to a heated o2.
I have not done a compression test.

 

This is in a 1988 C1500 chevy truck.