LT1-LT4 Modifications 1993-97 Gen II Small Block V8

My first top-end build

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Old 02-25-2013, 02:43 PM
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Default My first top-end build

Over the years I have bought most of my bolt-on upgrades, including brand new wheels and tires, (see signature) on Craigslist for dirt cheap.

I started collecting pieces for my top end build on my 134K (not hard) miles LT1 Z28.

Goals:
• 300 + hp at the wheels
• Fix oil leaks in the front of the motor
• Pass CA smog – Very clean now with a brand new OEM single cat - original owner bought new in 2009 and never installed it.
• Keep daily driver / weekend cruiser quality
• Do it on the cheap (buy new where I need to)

Bought OEM AL heads, cam, and intake on CL for $180 and dropped them off at my machine shop for porting, valve job, matching ported intake, and custom ground cam. No hurry on shop work since originals are still on car. Will post flow numbers in a couple of weeks.

Upgrade plans for top end:
• Custom grind cam (224/224 .525/.525 lsa112)
• New Comp cam 1.6 NSA roller rockers
• New Spring set, seals, and hardened 7.2 pushrods from Alex Parts
• New GM guide plates
• New 7/16 posts
• 30lbs injectors ?? See below

Other new stuff:
• Harmonic balancer
• Water pump
• Timing chain set
• Front end oil seals
• Gaskets
• Tune

Questions:
• Do I need a 52mm TB or will stock be adequate?
• Can the OEM TB be bored out to 52mm
• Do I need the 30 lbs (or higher) injectors?
• Do I need a new opti? (Mine is a 2yr old GM part)
• Are stock head bolts OK?
• Do I need to buy new push rods? (I have read that the stock rods are hardened)
• What am I forgetting?

Thanks
Old 02-25-2013, 02:58 PM
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my comments below

Originally Posted by BMX Dad
Questions:
• Do I need a 52mm TB or will stock be adequate?

after H/C it can be of benefit. you need a tune to accomadate, especially for automatic cars

• Can the OEM TB be bored out to 52mm

yes and better to bore a stock vs go aftermarket.

• Do I need the 30 lbs (or higher) injectors?

most would say yes, especially under WOT sustained (1/4 mi) conditions, FORD SVO 30's red tops. also requires PCM adjustment

• Do I need a new opti? (Mine is a 2yr old GM part)

if it works, no. certainly inspect cap/rotor and put blue lock tite on rotor screws. if cap & rotor are worn just replace with MSD cap/rotor kit

• Are stock head bolts OK?

I would replace with 12pt ARP

• Do I need to buy new push rods? (I have read that the stock rods are hardened)


with guide plates you do need hardened. Not sure what years LT1 had hardened. more important is a thicker wall PR as the stock ones can flex under high RPM which your new motor will see more of. Trick Flow is what I use .080 wall thick hardened. Given heads/cam I would use a PR check tool to see what length you need.

• What am I forgetting?

may now need a 255 gph Walbro fuel pump

Thanks
Old 02-25-2013, 03:16 PM
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******:

Excellent. Thank you.
Old 02-25-2013, 03:33 PM
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300+ at the wheels eh?

Bolts ons can net you 300rwhp.
Old 02-25-2013, 03:39 PM
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Who's cutting you that 224/224, sounds like a tpi cam. These motors have shitty exhaust flow so normally you see bigger exhaust numbers, like 224/230.

93 and 94 had hardened pushrods, and THINK early 95. To check there will be a little dot on one end where they did the hardness test.

What are AL heads? (Nevermind, I'm guessing aluminum)

Back to that cam inquire, by those specs I'm guessing he hasn't done much with lt1s before, are you sure you want to let him play with your heads?

Last edited by bufmatmuslepants; 02-25-2013 at 03:46 PM.
Old 02-25-2013, 03:40 PM
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Originally Posted by F0x Slaughter
300+ at the wheels eh?

Bolts ons can net you 300rwhp.
I was thinking the same thing? I had close to that with bolt ons only
Old 02-25-2013, 03:49 PM
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AL = Aluminum

I did not think that I would be pushing 300 with my bolt-ons
Old 02-25-2013, 04:11 PM
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Since you are in Cali I bet you have shorties instead of long tubes, so I'd bet you are around 275-280 if a 6 speed. You say single cat so you are 93 or 94, OBD1?
Old 02-25-2013, 04:20 PM
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My 95 had a single cat.

OBD1 and "OBD1.5" have single cats.
OBD2 have dual cats.
Old 02-25-2013, 04:24 PM
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CA-emission 95s came with dual cats but remained OBDI.
Old 02-25-2013, 04:59 PM
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ported heads and roller rockers would be recipe for some new pushrods, get a pushrod length checker to figure out what size you need... all and all thought head and cam will net you above your hp goals if done right...
Old 02-25-2013, 05:33 PM
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Originally Posted by RamAir95TA
CA-emission 95s came with dual cats but remained OBDI.
Another reason I don't like California
Old 02-25-2013, 05:39 PM
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low lift "custom" single pattern cam?

Are you committed to do this wrong or do you still have time to back out entirely and wait till you have some idea of what is good before you try and do it wrong again?
If the shop suggested that cam I would think twice before letting them touch the heads.
Old 02-25-2013, 06:10 PM
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I would diff look into another cam. Like already said most lt1 cams have higher exhaust numbers. I would also leave the stock tb and injectors. They will be more than enough for your combo. I would diff buy new arp head bolts. Youll will have to measure for the right pushrod lenght. Also if your not have blocked decked. Then i would run victor reinz .026 head gaskets. That will add some compression. Good luck
Old 02-25-2013, 06:23 PM
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Mr Gasket also makes compressed .026 gaskets.

.026 gaskets and head/blow will net you around 11.4:1 compression.

A lovely bump up from the 10.4:1 stock compression.


This along with bolt ons will hit 300rwhp.
Adding a cam will just be additional hp.
Old 02-25-2013, 07:22 PM
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Ive never had luck with mr gasket. They are packaged bad and stick to the plastic.
Old 02-25-2013, 07:30 PM
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I've heard the name Victor Reinz but other than that know nothing about them.
Old 02-25-2013, 08:13 PM
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My 95 is a federal vehicle, not CA, so that is how I get by with the single cat.

Yes it is an OBD1 car with the OBD2 plug - Loads of problems the last time I went through smog. Finding the OEM cat was a life saver.

No I am not locked into the cam so I can change.
Old 02-25-2013, 08:13 PM
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My 95 is a federal vehicle, not CA, so that is how I get by with the single cat.

Yes it is an OBD1 car with the OBD2 plug - Loads of problems the last time I went through smog. Finding the OEM cat was a life saver.

No I am not locked into the cam so I can change.
Old 02-25-2013, 08:22 PM
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Talk to AI or LE and tell them you're goals and plans with the car. They will grind you up a special cam for ~300 - 400 depending on which one you go through.


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