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LS4 swap begins


carkhz316
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Sorry I haven't been back for awhile. I'm still making progress, slowly but surely. I was waiting on all my engine parts, and still waiting on the clutch kit, though I was informed as of 7-19, it was "shipped". We'll see. Anyway, The engine is mostly assembled. I completely tore down the engine harness to rebuild from scratch. I can't go much further as I'll be integrating it with the existing Z34 chassis/ engine bay harness. I wanted to get as far along as I could before filling my garage with another car.

 

Edited by carkhz316
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On 6/27/2021 at 7:37 PM, Bake82 said:

Hey!  
 

Thought I’d pass along this info

 

 

TJ Hurrell on LS4 Nation Facebook group is in process of installing ls4/4t65e-HD in a 95 Grand Prix.  He has been posting some pics and small details.  
 

 

he has used the gxp subframe with spacers to make the subframe the right height.   
 

He had to bang the strut tower a little to fit the alternator.  
 

GM moved the ls4 to the drivers side 1-2 inches.   
 

I am thinking you will run into some major clearance issues if you try to keep the trans in the stock location.   
 

wonder if it would be easier to use aluminum subframe and have a mount welded on for the trans and then have custom length axles made?    Not ideal but might be the only option ?  
 

Just wanted to pass this along and point out TJ build on the Facebook group!  

 

 

 

Thanks for the heads up. I lurk the LS4 page and have seen his progress on that GP. It looks like a pretty cool rig. I have been hoping to be able to use the stock steel subframe as everything is in place besides the holes for the front motor mount. I haven't seen much success with custom axles either; though I suppose I've not really pursued that route before. I will be fabbing up a rear engine mount out of steel to replace the factory LS4 aluminum engine/ trans mount. I am a little concerned about the clearance front/ belt drive of the motor. I knew it would be tight, but I was hoping that massaging the strut tower would be the extent of the fitment issues. I guess I'll find out how bad it will be.

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On 7/20/2021 at 10:10 AM, carkhz316 said:

Thanks for the heads up. I lurk the LS4 page and have seen his progress on that GP. It looks like a pretty cool rig. I have been hoping to be able to use the stock steel subframe as everything is in place besides the holes for the front motor mount. I haven't seen much success with custom axles either; though I suppose I've not really pursued that route before. I will be fabbing up a rear engine mount out of steel to replace the factory LS4 aluminum engine/ trans mount. I am a little concerned about the clearance front/ belt drive of the motor. I knew it would be tight, but I was hoping that massaging the strut tower would be the extent of the fitment issues. I guess I'll find out how bad it will be.

For sure!   test fit first and then see how big of a hammer you need! 

 

If you need help with custom axles, I have a local shop who built me mine for my 3.8/282 swap (reatta OFA didn't work).  I paid $100cdn for it.  I supplied the 2 ends, they did the center shaft.   It has worked perfect for 3 years, 5-10,000miles.  

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  • 2 weeks later...

The short answer is quite a lot longer then the OE 4t65e that they came with.

the 284 is a very stout gear box. Keep the oil full and make sure the intermediate shaft is properly supported.

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13 hours ago, mechanic58 said:

So…are we going to have a “How long will the 284 last behind the LS4?” pool? $5 a spot?

It'll have no issues.   the 284 has been proven behind a 700whp 3800 turbo car and has been beat on and enough miles.  they're super stout transmissions.  

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  • 3 months later...

A little late, but better than never I suppose. I brought the car home from storage at my brothers so I could continue working on it. But, before I retire the current engine, I wanted to make a couple long overdue video clips to show that it actually runs and drives. After emptying the old gas and adding a splash of fresh 91, I took the back roads from my brothers house back home. I had my son with me to help with the cell phone recording, so excuse the shakey cam (he's only 9), And the dash cam clip is merely an old dash cam stuck to my sunroof glass. 

 

 

Edited by carkhz316
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  • 2 weeks later...

Just bought an '08 GXP LS4 and have been getting familiar with it.  It's a glorious engine, and it happened because I was thinking randomly what it would take to put an LS4 in my '92.

My suggestions:

  1. Don't go crazy with the cam, you'll regret it with a 284.  Cammed engines on manual transmissions are not merely challenging, they are next to impossible to tune for smooth drivability, and you'll feel every little quirk in the tune that'll make you forever try to fix it and hate the swap in the end.  Nobody else will tell you this, but trust me I've learned the hard way on multiple cars.  Stay as close to the factory tune and specification as you possibly can on a manual-trans swap.  The engine already makes over 300HP stock, and you're putting it through the same wheels you use to steer.  And now you're doing it through a trans that's short-geared for a high-revving V6.  It's already more than enough.
  2. Get the output-shaft support bearings that replace the oil seals for the 284.  It's Fitzall/TeckPak 75125LRB.
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On 11/15/2021 at 8:02 PM, crazyd said:

Just bought an '08 GXP LS4 and have been getting familiar with it.  It's a glorious engine, and it happened because I was thinking randomly what it would take to put an LS4 in my '92.

My suggestions:

  1. Don't go crazy with the cam, you'll regret it with a 284.  Cammed engines on manual transmissions are not merely challenging, they are next to impossible to tune for smooth drivability, and you'll feel every little quirk in the tune that'll make you forever try to fix it and hate the swap in the end.  Nobody else will tell you this, but trust me I've learned the hard way on multiple cars.  Stay as close to the factory tune and specification as you possibly can on a manual-trans swap.  The engine already makes over 300HP stock, and you're putting it through the same wheels you use to steer.  And now you're doing it through a trans that's short-geared for a high-revving V6.  It's already more than enough.
  2. Get the output-shaft support bearings that replace the oil seals for the 284.  It's Fitzall/TeckPak 75125LRB.

This is interesting because so far everything has made it seem like cam selection is a free for all if you're not bound to the confines of an auto transmission and it's inherent stall speed. Fortunately, my cam isn't very agressive, as it was implied to me that it was equivelant to a typical "Stage 1-2" cam offered by many vendors. I guess we'll see how much I hate it, lol. 

In an effort to mitigate the short gearing of the transmission, I plan on running a larger overall diameter wheel/ tire combo. I've been told this is a reasonable approach to the lack of traction and short gearing.

I wasn't aware of the those output shaft seal/ bearing combos. I'll definitely be springing for those. Thanks for the heads up.

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  • 2 months later...

So I've been dragging feet on this, but I made some more headway. I pulled the 3800. It's likely the last time this car will every be powered by a V6......probably. I installed my new clutch and pressure plate, bolted the trans to the LS4 and wheeled it back under the car. The final pic is with the engine sitting nearly in it's final position. A couple things I observed for the fitment: It IS tight. I knew I would need to clearance the alternator pulley, but it looks like I'll probably be cutting a recess out of the strut tower to accomodate it. The rest of the belt drive and pulleys will be millimeters away from the frame and strut tower. I was going to keep the PCM in the stock location, as the fancy blow-molded case is the same for LS PCMs, but theres not enough room between it and the belt drive, so I'm going to tuck it farther into the fender hopefully. Also, the oil filter hits the cradle, so instead of notching the cradle, I'll just remote mount the oil filter. Lastly, I need to make a front engine mount in addition to the rear engine mount, as both are too far away from their respective positions to be useful. Anyway, it's closer than I though for lining up. With the engine sitting in the engine bay, the front passenger cradle bolt was able to be inserted, but the rest are off by about 1/2 inch, which means the assembly is twisted clockwise a small amount due to the alternator interfernce. All in all, I'm pleased with how well it's fitting anyway.

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The intake is just resting on the engine for now, as I have a few modifcations to perform before bolting it down proper. That's why theres a blue shop towel under it.

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wasnt it relativly simple to put the 2nd gen alum subframe and suspension into the 1.5's?

 

alumn subframe  has the ls4 engine/diff mounts on the pass side and the std 65e on the drivers

Edited by Turbocharged400sbc
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1 hour ago, Turbocharged400sbc said:

wasnt it relativly simple to put the 2nd gen alum subframe and suspension into the 1.5's?

 

alumn subframe  has the ls4 engine/diff mounts on the pass side and the std 65e on the drivers

No, nothing lines up. The cradle mounting points are off by an inch or two, and the front is much lower, so you need spacers and need to cut the holes larger and do some janky nut and bolt setup to fasten it to the car, at least from what I've seen. Also, the cradle has no provision for the 5 speed transmission mount without some welding (I only have a simple MIG welder). I would ignore all that if it weren't for the issue with the axles. In the current setup, the axles are equal length. If I were to use the LS4 cradle, then everything shifts over to the drivers side, necessitating custom and different axle lenths side to side, which is a headache in and of itself. Unless anyone has suggestions for axle mix and match, or a way to fabricate or procure custom length axles, I feel like a little bit of cutting and welding of sheet metal will be much easier for me at this time.

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I've heard that about the 2nd gen subframe, that it's too way off to fit.  I'm a little surprised that the LS4 is so long, since I've heard of the Caddy 4.9L and Northstars fitting.  This was always a "dream swap" that I fantasized about, but from your experience, it sounds like it would be way over my head.

 

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  • 2 weeks later...

I dropped the engine and cradle back out last weekend after taking some more measurements. I was able to make a small horizontal cut to the top of the strut tower, and push the side in (with the help of a porta-power)about an inch, and now there is plenty of room around the alternator and the belt drive. I will weld the cut I made so that it's just a lap weld, similar to how the sheetmetal originally was. The next tightest point is near the rear (right side of engine) of the harmonic balaner and tensioner pulley, which were initially almost touching the lower frame rail. But, since the cradle mounting points aren't stationary, I was able to shift the cradle slightly, side to side, and get the room without any ridiculous sledgehammering. I still have to get my motor mount brackets welded up, and I also need to install a remote oil filter mount as there just isn't enough room for the oil filter in the stock location. The exhaust also fits the firewall/ downpipe area nearly perfectly, if not being just a bit closer to the firewall, so just the downpipe will have to have the lower bend altered slightly. Anyway, sorry no pics right now, as nothing really looks different. The LS4 radiator, fans, and condensor fit perfectly and the radiator mounts are the same/ same location as the Z34 radiator. All pieces are able to be installed with the engine in place too, so that's nice to know in the event of component repair/ replacement. I do need to modify the condensor fittings as the LS4 and Monte use different type of condensor fittings, but I have some options there and it's "just" the A/C system, which isn't the highest priority right now.Just wanted to update that everything is fitting just fine now, and it's coming down to the detail work to get it ready to be turn-key.

Edited by carkhz316
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  • 3 weeks later...

Great work so far!  very excited to see pics of how this all fits with the changes you've made!  very cool to see it fit in with the trans in the same spot!!  

 

Good luck with the rest of the work to do!!

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  • 1 month later...

I had seriously considered this swap on my 97 back in like '15/'16. I had scienced out a lot of the swap. 4.8/5 speed truck harness and pcm with tuning and spliced into a stock c100 plug, f40 trans, starter plate off a vendor on pennocks fiero forum, and a few other bits(I Know FAR from all of it). In the end what changed my mind was realizing just how much wiring work there'd be, lack of availability of affordable f40 CV axles, and the lack of off idle torque of the ls4(had a "work wife" at the time with a low mile 06 Monte SS I drove a few times). Still a super cool swap and glad to see it's going your way

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On 4/18/2022 at 11:09 PM, l67ss said:

I had seriously considered this swap on my 97 back in like '15/'16. I had scienced out a lot of the swap. 4.8/5 speed truck harness and pcm with tuning and spliced into a stock c100 plug, f40 trans, starter plate off a vendor on pennocks fiero forum, and a few other bits(I Know FAR from all of it). In the end what changed my mind was realizing just how much wiring work there'd be, lack of availability of affordable f40 CV axles, and the lack of off idle torque of the ls4(had a "work wife" at the time with a low mile 06 Monte SS I drove a few times). Still a super cool swap and glad to see it's going your way

The wiring has been one of the easiest parts so far, but that's always been my jam I suppose. I just grabbed a 99-02 truck harness (I believe it was a 2000 6.0) for the Gen 3-specific bits, but most of the LS4 harness is being reused. Once it's all broken down, there aren't a whole lot of items that are engine specific. Most of the wiring bits are integrated in to the chassis harness stuff, which I'm reusing most of the Monte harness for. Anyway, I was always under the impression that the LS v8's were pretty much torque all the time down low. I think its the steep gearing of the 4T65 makes them feel sluggish down low (I've driven a few as well). The 284 has relatively short gearing so it will make up for any lack of torque. But frankly, I don't really mind either way. This is just a project car/ hot rod for lolz. 

 

My metal/ welding guy is dragging feet on getting me some metal stock, so I'm going to try and source some elsewhere so I can get started on the engine mount brackets. That's all I'm waiting on at the moment so I can get the ball rolling some more.

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  • 2 weeks later...

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