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Re-building an older FI motor

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Old Dec 30, 2010 | 07:41 PM
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Default Re-building an older FI motor

Application: 97 corvette. 142K miles 97 LS1 w/ Vortech V2 S-trim 6 PSI (the vortech cog-belt kit not the A&A setup) Automatic w/ 3.15 gears

Other modifications:
- Vararam cold air intake
- ported LS1 throttle body
- LS6 intake manifold
- 1.8 yella terra rockers w/ comp 1218 springs
- LG Super Pro long tube headers w/ cats and x pipe
- Borla Stinger exhaust

Getting a considerable amount of blowby to where i'm only getting 4psi max according to my boost gauge. Aside from a lack of boost, everything is running smooth and quiet.

With the engine being the weakest link in my drivetrain, I'm considering re-building the motor to take full advantage of the boost as well as adding an ECS mild blower cam and up to about 7-8psi.

Questions:

1) Assuming I rebuild my existing motor, what components would I be looking to replace? Type, brands etc? Any extra components i should add for strength?

2) Assuming seperate costs for engine removal, parts, machine work, part installation, and re-installation of motor, what cost range would I be looking at?

Goals:
- This car is a street car/daily driver only, but it driven on freequent spirited cruises. I'm not looking to set track records, but i want to be able to back up my boasting.
- 500 rwhp range on conservative tune (currently sitting the 385 range according to dynojet)
- No less than 22 MPG fuel economy with cruise control at highway speed (70-80mph)


Thanks for the help.
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Old Dec 31, 2010 | 05:24 AM
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What is your budget? Being in TX, you have the choice of quite a few engine builders. I've dealt with LME and they have always done great work for me.
In your place, I would just get a forged shortblock and some fresh heads (or rebuild yours).
You are looking at around $3500 for a decent forget 347.
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Old Dec 31, 2010 | 08:51 AM
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Originally Posted by PREDATOR-Z
What is your budget? Being in TX, you have the choice of quite a few engine builders. I've dealt with LME and they have always done great work for me.
In your place, I would just get a forged shortblock and some fresh heads (or rebuild yours).
You are looking at around $3500 for a decent forget 347.
who is LME? I keep thinking LMR.
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Old Dec 31, 2010 | 09:38 AM
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http://www.latemodelengines.com/
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Old Dec 31, 2010 | 01:08 PM
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did you have 6psi and its has slipped to 4 psi now over time ? LME did my FI motor they do good work.
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Old Dec 31, 2010 | 04:54 PM
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Originally Posted by PREDATOR-Z
What is your budget? Being in TX, you have the choice of quite a few engine builders. I've dealt with LME and they have always done great work for me.
In your place, I would just get a forged shortblock and some fresh heads (or rebuild yours).
You are looking at around $3500 for a decent forget 347.
I second this. A well-built forged 347 with ARP hardware and dished pistons would go great with any FI application. EPS blower cam, lower compression ratio pistons/heads, and more PSI should get you to 500 without too much issue. I think the biggest issue you face is your MPG goal since you'll want to floor it all the time.

You will need larger injectors and a good fuel pump for 500 rear wheel HP. A rebuild on the Vortech wouldn't hurt either if the unit has high miles. I am in the middle of rebuilding my '01 LS1 shortblock with forged internals as a 347 and went with a 3.905 bore, Diamond -8.6cc pistons, forged connecting rods (SCAT is the cheapest I'd go, Callies/Lunati preferred), ARP head studs (more PSI = potential to lift heads from block), ARP main studs (to prevent cap walk), high flow/volume oil pump, stronger timing chain (I went with the SLP double roller/SLP oil pump combo), and medium-high grade Clevite bearings. I am shooting for 350-400 NA, 550-700 FI, reliably.

Last edited by ZexGX; Dec 31, 2010 at 05:05 PM.
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Old Jan 1, 2011 | 01:38 AM
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Originally Posted by ZexGX
I think the biggest issue you face is your MPG goal since you'll want to floor it all the time.
Yes, i'm running into that issue around town, but on longer highway cruises, looking at my digital insturment cluster and seeing the instant MPG upwards of 22 at cruise will make me smile. Right now I'm hovering around 21 with the cruise control. I think by freshinging the motor I should get some additional effeciency.

Another question: How do you guys feel about fuel pump boosters versus just replacing it with a high-flow unit? I'm pretty sure that bump boosters are just to keep from digging into the fuel tank and will eventually wear out the stock pump, but I want to make sure.
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Old Jan 1, 2011 | 04:50 AM
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Racetronic PnP fuel pump units with harness is what I used and they fed mine to over 600 Hp comfortably.
An in line fuel pressure regulator with return is something many fail to address. This will maintain cosistant pressure, especialy in higher rpms which will feed your injectors and allow them to reach their true potential.
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Old Jan 1, 2011 | 10:05 AM
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Originally Posted by PREDATOR-Z
Racetronic PnP fuel pump units with harness is what I used and they fed mine to over 600 Hp comfortably.
An in line fuel pressure regulator with return is something many fail to address. This will maintain cosistant pressure, especialy in higher rpms which will feed your injectors and allow them to reach their true potential.
My 97 is one of the early C5 vettes with a fuel return line that runs all the way to the motor and back. I think this should make things easier no?
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