Nelz

You know, there is a way to get around the Vortec intake...EQ lists CC305A and CH305B as Vortec style combustion chamber with 1.94 I and 1.5 E with 170 and 58cc combustion chamber. They also list a CC170BA and CC170BA2 with a 64 cc chamber (you'll probably have to have those milled to 60cc or ask about the CC305A/B to keep compression up) that clearly state Vortec combustion chamber/69-86 intake bolt pattern. I'm not sure but I think the RHS pro torker heads were also based off of Vortec heads and also list early and late model compatibility.

Air_Adam

This is actually true... one of my bosses at a previous job bought a crate 502 Ram Jet just so he could use the EFI system on the 427 BBC that went into his '69 Corvette. I'm the one that modified the manifold to sit under the L88 hood on that car (had to cut close to 2" out of the runners and make it all line up again... ugh). The throttle body is the same as the one on my LT1, which is the same size as the one the 5.0 and 5.7 TPI cars used. I was surprised to see that same TB on the big 502, but I assure you it was the same one - I saw it myself.

TxTtopZ

Engine Quest has many offerings for sure, but, without trying to line up the ports and looking at what needs to be drilled/ported etc.

Mayt13

Check this article out, HP does not stack the way you would expect:

content://com.sec.android.app.sbrowser/readinglist/0511170249.mhtml

The reason IROCs are so great is you don't have to do ANY of that. Almost all GM FE-RWD powertrains are compatible. You want 330hp? Swap in a LS1 and T56. Done. Or go the route I prefer and trust displacement. Get a four bolt main 350, bore it .30 over, swap a 383 forged eagle rotating assembly, put in a mild cam and retrofitted roller rockers. Have someone rebuild your heads, get high flow injectors and bam. Your done. 400 horse easy. Or even consider swapping In a BBC if your desperate for power.

This is the whole point of a chevy, use the power train appropriate to you needs. I love my lb9, but their junk for a build.

okfoz

You are very correct in saying that if you want power, there is no replacement for displacement, and you can get comparable HP from a TPI. However with an LS1, LS2, LS(whatever) when you gain HP you also gain MPG... I would love to have 300+ HP and get 30mpg highway. As it is now, 24, 25 mpg highway and I am throwing a party. You make a hot 383 and you might get 20mpg but the same hp & worse drive-ability. One of the things about newer engines & computers you can really get some good HP numbers and still not feel like its a streetlight-streetlight racer.

Don't get me wrong, I love my TPI, nothing looks better when opening the hood, but I really want an LS engine...

John

Mayt13

I would argue that a properly built TPI 383 should only 10 city and 12-14 hwy. Larger charge=>Greater fuel consumption, especially since TPI is not all that efficient (no where near as much as the LT1 setup). However, it should also make almost 600 ft-lbs of torque. With any build you have to decide what is important to you. If its fuel economy, then go with the LS platform. If its torque and absolute reliability, i.e. the ability to fix it with wire, crimp connectors, tubing and electrical tape, then go with the TPI platform. I love low end torque because it is more useful than HP in 9/10 situations. I keep up with LS motors up to 60-70 all day with a LB9 (Smog delete/headers/not cats) with a T5. Keep in mind that no amount HP is out of reach when money is not a factor (you can build an LSX or LS1 to well over 1000 horse). You may want to consider the fact that just a LS1/T56 will cost you 4500, which is worth more than most IROCs.

okfoz

I would agree that point that an LS motor is probably more expensive than most third gens.

TPI is not that bad on Fuel economy... I got 26mpg average from Asheville, NC to Flint MI on the highway in my Formula 350 Convertible...

Mayt13

Formulas have the lowest drag coefficient, but running a 383 probably means running at least 275s in the rear. I assume your running 225-245. Rolling friction can also nerf mileage. That plus the variance of who's driving. But yes, put in a firebird, in top gear at 75, it should get around 21 (assuming there are no ridiculous grades). However, down here in vegas, in a Camaro, driving in heavy traffic all moving at 90, where no one lets you in and foot down merging is mandatory, locally on the freeway, with a ton of gradients, in 110 degree heat, with your AC blasting and your stereo on, you would be lucky to get 15.

LiquidBlue

great opening post and thread!

1MeanZ

iTrader: (9)

My 383 makes about 420-440hp and I get 28mpg hwy. It can be done. An LS is not the only way to get power and fuel economy.

Fast355

iTrader: (2)

^^^Agreed^^^^

Just got into an argument with a couple of guys over on gearhead-efi.com that thought a LQ4 was the only way to make power relatively cheaply. I have a heads/cam/marine intake/headers/exhaust on my L31 350 vortec and run in the 400-425 HP range and more than equaled the power of a stock cam LQ4 from idle-redline and kept up with his cammed setup from idle-5,000 rpm with a smaller, older 350. Still get 19 mpg highway in a brick of an Express van with a power robbing 4L80E with only a 0.75:1 overdrive and 9.5" 14-bolt with 3.73 gears.

83 Crossfire TA

iTrader: (2)

Well, since this thread has been revived, I guess I'll update:

And my own counter to all the arguments why you can't run a decent time with an LB9:

snip long list of why a lot of the "gosple" as per TPIS and others is wrong, you can go back and read what I wrote.

So since then I found a stock high mile 87 TA, LB9 + T5 3.08 rear gear car (By high mile I mean this thing burns a quart of oil in less than 1000mi), and by stock I mean really stock, when I bought it the only thing that wasn't stock on it was a lightweight flywheel/clutch which the PO put in it which makes it impossible to launch well, I wish it was stock, the car would be faster.

With tuning, an ignition (Crain Hi-6 + matching LS92 coil) an old school SLP cold air intake (I would argue about as good as the factory camaro TPI intake) and an exhaust (bits and pieces I had laying round, I think an over the axle pipe from and SLP TTL exhaust, dynomax ultraflow welded muffler and single 3" tailpipe I ran 13.9's at the track.

At the end of last year, I added headers, sticky 26" slicks, 3.50 gears (I had a 9" ford sitting around, better gearing but also close to 100# heavier than the 10 bolt) more tuning (the MAF died and I had a megasquirt sitting around so that was the cheapest way to get it running again) and some rear suspension parts (I would argue totally unnecessary to make this setup hook with the slicks, but while I was swapping the rear I might as well put them in).

I was having issues with the coil wire popping off that day which was hurting the top end some (in this video you can hear it in the burnout box, it was popping like it was hitting rev limiter at about 3400rpm but it was just acting a little weird going down the track), and ran a 13.622@99.89:


For any neighsayers, that someone did something to it before me..., I've taken the engine apart this spring and posted pics with casting numbers... on ****** Militia, it is what I say/thought it was, even down to the cam number and dished pistons.

A much fresher LB9 + 5 speed car, like a lighter weight formula that came with a factory 3.42/3.45 gear (I could have sworn that there is a way to get 3.73's, that would be faster, or swap some 3.73/4.10's), stock clutch, with headers, exhaust, cold air intake, an ignition box (or very careful ignition tuning) tuning and sticky tires would be able to beat this easily.

Next I intend to go _much_ faster keeping the stock worn bottom end.

83 Crossfire TA

iTrader: (2)

And just in an effort to keep info in this thread accurate:

Lightly equipped Formulas tended to be the lightest of the TPI cars (a lightly equipped iroc/Z28 isn't far behind, and the TA's were the heaviest), but they were not the most aerodynamic, the 82-84 non aero package TA's were (they still had some extra body work over the formulas, like spats in front of the wheels..., but they didn't have the full skirts...)

Oh, and carefully setup these cars can pull a lot more MPG than most of you car claiming with a 305