I originally listed a thread advertising a crossfire to LT1 conversion.

What I am really looking for is any upgrades I should make to the LT1 before I put it into the car. I am not concerned on how much money I could save by rebuilding the crossfire or going with a different motor combination. I have the parts and will make them work.

It originally was an iron head LT1 from a 1996 Impala. It came from the previous owner as a complete system, motor, trans, wiring harness, ecm. he also supplied aluminum heads, extra intake, complete Corvette air intake system, as well as a Mezierre water pump conversion for the cam driven LT1 water pump, and fuel pump for the MPI system.

I'd like to know what experienced LT1/LT4 owners have used, have had luck with, maybe some good combinations of parts.

While I am new to owning a Corvette or working on LT1/LT4 motors, I am not inexperienced to working and rebuilding cars.

 

depends out how far you want to go.

I picked up a use set of LT1 heads that I was going to have ported.

For the $$ it would have taken to get them rebuilt, I bought a brand new set of AFR 195 Eliminators, then had the stock intake ported to match.

If the bottom end is fine, leave it.

If not, a 383 is about the same about of $$ as a 350

If you want to go hogwild take a look at my sight and see my supercharged 383

 

Right now I am looking at basic upgrades. I don't intend to doing any machining. If I have to do machining, then I will be building a 383 with a carb setup and later changing to EFI.

As long as the bottom end is good, it will be left alone. I have been told the LT1 cam with 1.6 RR will perform better than the LT4 "Hot Cam" kit. I am wondering if it would be worth the upgrade to an LT4 setup.

Something else I am looking to do is port matching the intake and upgrading the TBI unit and MAF.

I will be installing full tube headers and at some point a Corsa exhaust. In the meantime it will get a home built custom unit.

Something else I may do before installing the motor is upgrading the Opti-spark to a multi coil LSx setup.

Thanks for any help.

 

Here's a thought for you. Might make your life easier.
For about 400 bucks you can get a ecm that will allow you to utilize your existing harness in the 84 and turn it into a speed denisty m/p setup. You'll have complete tuning ability right from the get go.
I know you said your gonna carb it first, but this may save you some money by not doing it twice.

Since that ecm your gonna put in is for a TBI/Maf its gonna be useless anyways when you upgrade. All the time spent with putting in that harness is gonna be a waste of your time.

 

I've been studing the LT1 to LT4 upgrade for several years. I've been collecting parts a little at a time and now I'm close to beginning the project. Here is what I've learned. The top end (heads & intake) of the LT4 is a simple bolt on to the LT1. The GM Hot Cam Kit will vastly improve the performance and is proven to be very streetable. I've gone deeper into the absolute upgrade to the LT4 and would be happy to explain what I'm doing. You can follow my threads in this section.

PS. There are several differences between Camaro & Impala LT1s and Corvette LT1s.

 

You've been told wrong. The stock LT1 cam with 1.6 rockers will have specs similar to the stock LT4 cam with its stock 1.6 rockers. The LT4 Hot Cam kit will make a big difference over either.

 

The LT4 Hotcam is much superior. Just look up and compare the total lift numbers. If you can do the work yourself the "kit" is a good upgrade for you. BTW a Corsa exhaust is big bucks with very little bang. Go LT headers and duals for power.

 

Ok, so that's what I'm looking for. Right now I have the aluminum LT1 heads so I plan to stick with them and do some porting to help the flow. I'll definately look at the LT4 hot cam kit. I'm really looking at the EFI Connection LSx ignition upgrade.

What is a good set of long tube headers? What size tubes?

Since the LT1 only uses one O2 sensor per bank, will deleting the catalytic converters upset the computer? I initially planned to install my own exhaust with Dynomax race bullets or muffler delete. I'm a little confused, everyone on this forum has sung the praises of the Corsa exhaust.

 

Is it worth time to port the intake to fit a 58mm throttle body?

 

Some say yes and some say no. I don't think it's a worthwhile mod for your power levels. The 502 HP 502 cubic inch GM crate motor uses a 48 mm throttle body.....just like your stock one.

 

Just an update on the rebuild. I've opened the motor and started to look. So far the top end looks real good. I'm keeping my fingers crossed the bottom end looks just as good. Small hang up roght now, the harmonic balancer needs a puller I don't have right now.

I took the aluminum heads and the intake to Performance Clinic to be port matched. I'm waiting on a gasket from BBK to get the inlet ported to 58mm.

Going to order the "hot cam" kit and the poly bushing kit soon so the suspension can be upgraded while the motor is apart.

 

You're going to have a nice mild upgrade with a great big difference in power from the crossfire. Get either a single or double timing chain set. The double roller will require so machining to the front cover for clearance. I use a lot of the Cloyes 3157 single roller set. It has real beefy rollers and does away with the water pump drive.

A lot of people have been very happy with the OBX headers. Just do a search in the Tech forum. They're 1 5/8 and that will be plenty for your build and then some. You really don't need a 58mm TB right now. The 48 flows well enough to make around 500 HP. GM uses a 48 on the 502 engine making over 500 Horses. That's just some money you could save.

There may be a few horsepower there but certainly not the best bang for the buck. The F.A.S.T. system is a well proven design and works well but an option might be the Bailey LTCC. I've used it with 8 coils and have had great service from it. I believe it's around $400 including the controller and the harness.

I made some brackets/fuel rail covers to mount the coils on mine and all the wiring is underneath. Kinda like this:





Just an idea for you on one way to do it.

It won't hurt a thing at all to delete the rear Oxygen sensors with the OBD1 system. It doesn't even look for them. Don't forget that you're going to need a tune also. If you have performance mods coming in the future you may want to get a cable for your ALDL port and have the tunes and the tune upgrades e-mailed to you and install them yourself.

So simple a caveman could do it. There is free Datalogging software available so you can scan your parameters and show the tuner how it's running in the real world. Makes his job easier and your downtime less.

Good luck with your build and have fun with it.

 

Ty for the info on the timing chain, since I'm converting to electric, I wanted to get rif of the drive. Is there a need to install a plate in place of the drive, or is it ok being left open?

I was also looking at the EFIconnection ignition conversion and possibly go with one of their timing covers. Then start searching the junkyards for coils and make my own mounts. I also thought about mounting off to the side or on the firewall.

If I upgrade the throttle body, I will only be going up to 52mm for now. Since it is being port matched, it's no extra cost to open it up to 58mm for the future, if there is a need.

 

Is the lt4 hot cam kit, the actual cam that comes in the lt4, which would upgrade an lt1, or is it an upgrade above the stock lt4 cam. I recently picked up an lt4 and I am just trying to get all the info on it. Thanks

 

The Hot cam is not the stock cam in a LT4. It's an upgrade. The stock LT4 had somewhere around .475 lift and the Hotcam has .525 or so.

 

Where the water pump drive is pressed into the block can be left unplugged, the timing cover will need to be plugged.

 

I planned to have the hole welded up for now. EFIconnection.com sells aftermarket timing chain covers with a hole, without a hole and enough room to fit a double row timing chain.

 

WOW, $345 for a timing cover!!




LT1 Billet Aluminum Timing Cover without Water Pump Drive
Views:

Part #: 120-00015
Price: $345.00
Minimum Qty: 0
Price Break Qty: 2
Price Break: $330.00
Qty in Cart:


Additional Details:
This billet aluminum timing cover fits all 1992-1997 LT1 and LT4 engines. This timing cover is required when using a double row timing set with crank reluctor and sensor. This timing cover does not have provision for the water pump drive and should be used with engines fitted with an electric water pump.

 

I have the efi connection 24x setup running the LS1 computer on my LT1 (Camaro). If you have it all apart, now is the time to get all this stuff installed. I bought the plain kit and rewired the harness myself (not hard, just time consuming)

If you go for the hotcam, I would expect you would put down around 320-340 with no other mods. Keep in mind the springs on the hotcam setup won't support any other type of cam that has higher lift. I think the springs are only good to .525.

As for the rest of my setup, I use the lt4 timing set with a 96+ cover and have a Mez wp. It's a 355, I run ported intake/ported heads/58mm/LPP stepped longtubes and 30lb SVO injectors. I made 360rwhp with a baby crane (powermax 2030) through a 12bolt which would put crank HP around 425-430. I recently dropped in a more aggressive custom cam to see if I can get to 400rwhp

 

merim123, I'm glad to hear that. I really want to install the EFIconnection kit now so I won't have any trouble with the optispark. I have the heads at the shop right now getting ported and prepped for the LT4 hot cam.

They cleaned and prepped the heads. All surfaces were square and true (bonus). The only real machining needed to be done was cutting the valve guides down to clear the higher lift and a valve job. One helicoil was bad so it was replaced and there was an exhaust bolt broken, so it was removed and all the bolt holes were cleaned. They are also removing all the tangs on the helicoils so the ARP studs fit properly.

The heads will be ready on Thursday, can't wait. Just need to get a hub puller so I can finish tearing the motor down.