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LTX and LSXPutting LT1s, LS1s, and their variants into Third Gens is becoming more popular. This board is for those who are doing and have done the swaps so they can discuss all of their technical aspects including repairs, swap info, and performance upgrades.
It is finally time to get my Firebird back together.
I had this swap planned for quite a while.
Here is the car as it was after the LS3/T56 swap.
You can read up on the build here if interested. LS3 T56 swap in 91 Formula
Hard to believe that project started 10 years ago...
For 5-6 years I had an LS9 engine sitting in my garage in pieces.
When I initially planned to build it, covid had disrupted the supply chain & most of what I needed was not available.
Then, just over 2 years ago, I got involved in an S10 build that needed an LSx swap.
The Firebird gave up its engine for the cause.
After a few years of being apart, I finally got the time & ambition to put the car back together.
It is not going to be a stock engine either... I'm shooting for around 900 at the wheels.
I collected all of the parts & have everything ready for assembly with the intent of it running by spring.
It all started when a guy was modifying his car & pulled the charger to install a larger one.
While apart, he then decided to install better heads, and once again before anything was put together, he also decided to go with 6 bolt block.
This is how I ended up with a low mile engine that was apart...
When I got it, the short block was together.
That quickly changed when I decided to convert it to a wet sump engine.
Unfortunately, the Wet sump conversion is different than the LS7... I thought it was a matter of changing the oil pump, oil pan, timing cover & drilling the engine for a dipstick.
It turns out that the front of the crank has a keyway to drive the blower pulley, which is at the end of the crank & it also drives the oil pump/timing gear.
When you swap to the shorter oil pump the lower keyway no longer reaches the oil pump drive.
This is compounded by the fact the crank is stepped & must be turned down so a standard balancer will fit.
Here you can see how the crank was turned to shorten the stepped area back to there the timing gear is.
A full-length keyway was also machined in to drive the timing gear while also positively locating the balancer for the stress of the supercharger.
It was also shortened about 1" to the same dimension as a wet sump LSx crank.
The crank is also a forging instead of the common cast crank as in most LS engines.
Note the heat treating & extra balancing/lightening from the factory.
They are quite different than the LSA... Aside from the rods being titanium & pistons are forged (unlike the LSA), the piston pins are also a larger diameter (.984") & the rods are .108" shorter.
The dip stick hole needed drilled at this time.
Do not spend $90 on a drill fixture... a flat boss is already there & it is very easy to do.
It took 3 drill bits & about 5 minutes to accomplish.
I installed main studs & had the block align honed to make sure all was good.
Many people do not do this step & it can be disastrous.
It turns out the mains bores moved very slightly, (a max of .0006" at 1 place), so the align hone was necessary.
A set of King coated bearings were also installed at this time.
Good call on the aling hone, although 6 tenths is within measurement error. I had no idea the LS9 didnt have the dip stick hole. I know it was dry sump, but GM had a habbit of using machining programs for numerous LS blocks.
Yes, the LS7 & LS9 do not have dipstick holes as it was located in the oil tank.
It is nice to have a dial bore gauge that reads to the tenth (.0001), but the more resolution you can measure, the more you worry about the tolerances.
I figure since this engine is capable of over 7000 rpm & 1000 hp, I did not want to cut any corners.
Looks great. I had to do the same thing with my crank scraper as they had yet to offer one for main studs. Took a lot of tweaking to ensure I had clearance around everything. Which one did you go with? Also, I like how the LS9 valley cover has an extension on the PCV port.
It was close but the LS9 is quite different. The big ends of the rods are larger than most & the center crank throws were also larger.
It only took me about an hour to get it fitting properly.
I was going to port the factory heads, but by the time I paid for porting, springs & retainers, I figured it was better to buy new & sell the old heads for a similar investment while having a better end product.
I can say the Frankenstein heads are nicely done.
The head bolt holes were reamed for the larger 12mm head studs & also shaved to get the compression up slightly.
I had the supercharger ported by Jokerz Performance.
The snout was extensively modified/welded to mate up to a 102mm throttle body.
It was extensively welded underneath to remove the factory water pump clearance lump as well as removing the lower bolt boss for more flow.
The runners were also fully CNC machined.
Also, the bricks were reinforced to support the higher boost levels expected.
Another interesting dilemma is the factory crank has a 9 bolt flywheel flange & all ZR1 Vettes were manuals.
Since I'm going with a 4l80E I had to find a flywheel.
TCI makes one but was backordered.
JW Performance also makes one but they were not in stock.
After a call to them, I found out they make to order & will drill a blank flexplate for me.
Awesome service from this company... it was on it's way to me in a few days.
The other unfortunate part is ARP does not make a set of 9 bolts to install so I had to buy 2 packages of 6.
It's the little things that add up.
I also added a timing pointer so I can verify timing with the Holley EFI.
It amazes me how people trust factory production tolerances.
I also did a trunnion upgrade on the factory rockers.
I chose to stay with stockers since the lift was limited to .630"
The pushrods ended up being .4" longer than stock largely due to the different cylinder head geometry.
-I do NOT like the Exhaust Rubber/ Viton O-Rings on your amazing Frankenstein Cylinder-Heads...
They hold-up okay in a Normally-Aspirated Build, but not so well with the added Exhaust Temps with the Supercharger...
Forget about using them with a Turbocharger Build.
-Switching to Cast Aluminum Transmission Oil-Pan will add some Support/ Rigidity to a Stock 4L80E Case, and also aid some in cooling...
Also it is easier to add a Temperature Sending-Unit.
Enjoy you Build!
Last edited by vorteciroc; 03-13-2023 at 09:40 PM.
I am also concerned with the exhaust o-rings... I will slip in a set of gaskets, if necessary, down the road.
Fingers crossed.
As for the pan, it was necessary with the trans brake for internal clearance.
Strength wise, I am trusting one of the most regarded trans builders in the industry.
I'm more concerned with the ground clearance to some extent as my car is very low.
As an FYI... I will get temperature readings from the internal factory temp sensor.
It will have a thermostatically controlled fan powered cooler on it also.
Prior to the engine install I knew i had a wiper motor clearance issue.
I started by cuting 1/2" from the mounting feet for more clearance.
I could not go further as the hole in firewall was the limiting issue.
I then remounted the rubber bushings by drilling into the sides of the bracket into the bushing groove to anchor them into place
Here is the final product.
I left 1/8" of rubber exposed to prevent contact between the firewall & motor.
unfortunately, it was not enough unless I moved the engine forward, which is limited by the headers... the 2" primaries use up a lot of space.
I am now cutting into the plastic cover to get the last few fractions of an inch.
Have you looked into the Detroit Speed wiper motor? Takes a little fab work but it very low profile. You can also go with a Nissan Maxima unit as detailed by board member LSXMatt.
I heard the Nissan motor works but is not really correct with respect to the wiper stroke & also the delay function is compromised.
Even though I do not drive it in it the rain, I could not do a half-assed modification.
It will look factory when it's done & work properly, without cutting up the car.
To date there is not a hole in the car that was not factory installed.
Just a personal goal, but I pride myself with making things fit without cutting up anything.
To be clear, I did notch the crossmember for the AC compressor, but I see AC as a necessity.
Although looking back, I could have went with a high mount unit as I did on my S10.
It will look factory when it's done & work properly, without cutting up the car.
To date there is not a hole in the car that was not factory installed.
I get it. I admire this build greatly. Keep going.
Have you looked into the Detroit Speed wiper motor? Takes a little fab work but it very low profile. You can also go with a Nissan Maxima unit as detailed by board member LSXMatt.
Look up a 2002 Chevrolet Impala Wiper Motor, and tell me if it looks familiar?
The one on my S10 also looked like the proper orientation, but the number of wires were different.
Without the delay wipers, it would be an easier swap.
I would use the two part plastic epoxy from JB Weld. It works amazing, dries black and dries hard. You could then sand it and paint it to look OEM. Plastic welding is hard unless you melt in the metal biscuits, which then look ugly when complete.
I got my trans & oil coolers.
I'm trying to get everything aligned before I start mounting things.
Fans will be thermostatically controlled.
The chromoly yoke was installed & I measured for the driveshaft.
My driveshaft came in yesterday & fit nicely.
The quality of these driveshafts is amazing.
I'm also in progress of getting the rear mounted battery installed.
Cables are run & I installed a rear disconnect that is removable & not seen from the outside, but can be easily operated at the track... pictures to follow.
I did some work on the battery mounting.
I wanted a disconnect for the rear mounted battery but did not want an ugly handle sticking out of or under the bumper.
I started with a BMR battery box in the spare tire well... it fit rather well.
Next was getting a disconnect.
I opted for the 2 pole Moroso version with remote shutoff lever that I can also use to shut down the car.
I ran the power feed for the EFI to it so it immediately kills the engine.
I found that there is a small gap at the corner of the taillight that will permit the lever to pass through.
If the rod is properly supported, it also allows the handle to be removed & reconnected with no trace of an external switch.
The next item I was concerned with is to properly vent the battery.
Optimas are not supposed to outgas unless overcharged, but my luck with Optimas has been less than stellar in recent years & the cost is way above a regular battery.
I chose to use a standard lead/acid battery but wanted to externally vent it.
I ended up using a battery for a CTS-V Cadillac since it is factory rear mounted & uses a separate tube to vent outside the car.
It barely fit in the BMR box.
I made a few tweaks to the bolt down bracket.
I'm routing the cable through the interior at the rocker pinch weld & it will come out inside the fender & run to a junction near the factory battery location.
Progress on the car has been slow as I got involved in getting my S10 ready for summer.
It turns out my engine was sitting crooked in the engine bay, so I needed to raise the right side approximately 1/2".
FYI, they never intended the frame mounts to be removed with the engine or suspension in the car.
Also, the AC compressor blocks access to the engine side of the mounts.
So, only 4 hrs. later the engine is level.
I did find out that my 4L80E crossmember was directly in front of the exhaust, so I cut it in 4 pieces & re-welded it.
Here was the unmodified part.
Since I was making more exhaust room, I also raised the mount location 1" to get the transmission where I wanted it.
Note gap in picture above.
Here is the modified part.
Once back in the car, I started mocking up the exhaust.
Here is what is left of the T56 y-pipe.
Now I just have to fill in the gaps... along with a set of cutouts.
Is the 3.5" hawks setup relitively quiet without the cutouts? I used to have a 3" borla that was very quiet until i opened the cutout, i loved having both options.
I did have the reverse flow muffler that has since been discontinued. It was very mild sounding, but I used this muffler on my S10.
I have not yet heard it with the straight through louvered core muffler yet, which is the only one now available.
I've heard it is still rather quiet, but I cannot confirm.
Is the 3.5" hawks setup relitively quiet without the cutouts?
LOL! No.
It has a full size muffler case but it is 3.5 inch straight through end to end. I don't want to clutter Lonnie's thread with my videos but let's just say I have permanent hearing loss from it. The volume goes down quite a bit if you can get the engine cruising below 1800 RPM. And of course results will vary depending on the nature of your engine (higher compression is louder).
There is no magic muffler that is quiet and flows a lot with a single exhaust system. You either do a straight through muffler and be really loud, or you plug it up and get quiet. There is so much exhaust flow going through that single pipe that any restriction in the muffler is detrimental (if you need it).
It has a full size muffler case but it is 3.5 inch straight through end to end. I don't want to clutter Lonnie's thread with my videos but let's just say I have permanent hearing loss from it. The volume goes down quite a bit if you can get the engine cruising below 1800 RPM. And of course results will vary depending on the nature of your engine (higher compression is louder).
There is no magic muffler that is quiet and flows a lot with a single exhaust system. You either do a straight through muffler and be really loud, or you plug it up and get quiet. There is so much exhaust flow going through that single pipe that any restriction in the muffler is detrimental (if you need it).
thanks for the info, I am debating what to go with when my LS1 goes into the formula - I really love the new two out the left option hawks is offering, but I am not looking to wake up the whole county. Maybe I can see what it sounds like in their showroom before I decide.
thanks for the info, I am debating what to go with when my LS1 goes into the formula - I really love the new two out the left option hawks is offering, but I am not looking to wake up the whole county. Maybe I can see what it sounds like in their showroom before I decide.
How much power do you expect to make? If the LS1 is stock, I'd run a normal 3" cat-back with a cat converter. Headers will add to the noise but not too much. A single 3" system with headers on these cars is not hard on your ears at all (with 350 to 400hp). When you add lots of power and increase the size of the exhaust, that's when the noise becomes a problem.
Although I never said the Hawks 3.5" wasn't awesome.... it's the best sounding single exhaust ever to grace a 3rd gen.
As you modify a car you keep crossing lines of civility, and eventually there is a line crossed where the car is no longer pleasant to just putz around in and it becomes more about performance to make the misery worthwhile. If you want to howl and scream with no drone then that exhaust will do it fantastic.
Awesome build. I plan on putting a Kong Supercharger in my 91 GTA in the future, so hearing it fits under the hood is excellent to hear. I know Speartech did it, but they flipped the bricks around to have the outlets come out the back of the housing
I would proceed with caution as mine barely clears & may be more related to mount type & engine angle.
5/16" is next to nothing & doesn't leave much room for error.
Are you using the Kong lid? It may be slightly different than the LS9.
Good luck & keep me updated as I have been looking at the same 2650 but had some concerns.
Mine will be going back on the lift after being ignored all summer to hopefully be ready by spring.
I am a long way away from doing anything like this to my car unfortunately. Does it come close to the skin or to one of the braces?
I don't like Logos, so I was thinking about getting the Kong stuff on top milled off, so I could probably shave the lid if needed to gain some more space.
01-28-2023, 08:08 PM
