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| LS4 / F40 swap - fieroguru (Page 136/216) |
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motoracer838
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MAY 27, 08:39 AM
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Guru, what is the dia of the bolt circle on the LS4 crank?
Joe
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fieroguru
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MAY 27, 09:17 AM
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| quote | Originally posted by fierogt4e:
As I read this AWD section for the second or third time I see a separate gear case to move the output farther towards the passenger side. Sort of a transfer case. It would keep it simple I think.
You could use 2, 3, or 4 gears depending on how far, and the direction of rotation you need to clear the AWD unit and the engine sump. Angle it up or down a little if needed. Bolt it on over the pinion support, using the 7 AWD pinion support bolts. And with a bracket on the output end.
This way you could adjust the ratios to work with whatever you find for a front diff.. 50:49 will give 2% over drive I think. This gives you more options. More easily replaced if damaged.
Best of all separate cases could be put in your store for hill chimers, rally, off road, kit-cars, and so on.
AWD Fiero! That's just cool.
P.S. Slam that 4X4! |
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Simple is a matter of perspective.
My plan is to use an off-the-shelf AWD unit, then make a new case where I can reuse the off-the-shelf gear set in the custom case.
That way I only have to make 1 part (albeit with a significant amount of machining required), but the bearings, gears, shafts, and output housing will all remain stock. In the event I frag a gear, then I just need to pick up another $250 awd unit to get a replacement part.
I doubt this would ever be a product I "could" sell... just not that many people running F40 transmissions in Fieros, even fewer who would want the weight or complexity of AWD, and few still would want to pay for the upgrade that would require an AWD differential, AWD unit, custom case, custom fuel tank to allow room for the driveshaft to the front, front differential, front axles, and custom fab to convert to driven front wheels... With me doing all the work, the first one will likely be in the 3-4K range for the conversion.
It will probably be similar to the 3.09 final drive upgrade. It has been available for 8-9 months with very little interest... But I absolutely love it, so all the effort to do it was well worth it!
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fieroguru
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MAY 27, 09:23 AM
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| quote | Originally posted by motoracer838:
Guru, what is the dia of the bolt circle on the LS4 crank?
Joe |
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3.127".
Same as all other LS based engines except the LS7/LS9. The center pilot bore is the same as the 1 piece rear main seal SBCs (2.071"), but the crank pattern isn't the same (but the holes only need some slight slotting - my first prototype used a mid 90's LT1 flywheel).
Spec offers a LS4/F40 flywheel now, so I stopped making them.
If you want to stick with the F23, get a billet steel LS1/LS2 flywheel (they are about 0.81" thick) and turn the OD down to accept the 142 tooth ring gear and drill the Fiero pressure plate pattern.
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motoracer838
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MAY 27, 10:31 AM
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| quote | Originally posted by fieroguru:
3.127".
Same as all other LS based engines except the LS7/LS9. The center pilot bore is the same as the 1 piece rear main seal SBCs (2.071"), but the crank pattern isn't the same (but the holes only need some slight slotting - my first prototype used a mid 90's LT1 flywheel).
Spec offers a LS4/F40 flywheel now, so I stopped making them.
If you want to stick with the F23, get a billet steel LS1/LS2 flywheel (they are about 0.81" thick) and turn the OD down to accept the 142 tooth ring gear and drill the Fiero pressure plate pattern. |
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Thanks, This thread is hands down the best source for LS4 info...  I am going to take a look at using the flywheel I got from CHRF for my Nstar. Are you aware of any LS4/F23 swaps, my search has only turned up 4t65 auto's and F40's?
I made the decision last night to pull the plug on the Nstar. (Been wrestling with this for a long time, the fact that I can pick up several LS4's locally for less than $500 each helped, that's less than I'll spend to fix the Nstar headbolt issue...) I honestly think I'll get the car up and running sooner and with less hassle going LS4. Am I correct in assuming the LS4 has a 58x reluctor?
Joe[This message has been edited by motoracer838 (edited 05-27-2018).]
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fieroguru
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MAY 27, 02:54 PM
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There are a couple of LS4/F23 in the works. There have also been a couple of LS4/200R4s done in longitudinal format.
The 05 and 06 are 24x and the 07+ are 58x.
It was a hard decision to move on from the SBC, but now that I have, I would not do anything else besides an LS swap going forward... they are AWESOME!
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motoracer838
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MAY 27, 08:26 PM
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" I'm too deep in parts to back up now"... Over the years, I've let this mindset to lead me down the rabbit hole only to wind up dissatisfied in the end or into a dead end that I had to back out of at even more expense, time to change that... And how many Nstar threads end happily??? Not trying to rag on the Nstars, just acknowledging some issues with them... My project started almost by accident, but I've never really got excited about it. (might have a had role in how long the car has sat, easier to let it set than deal with it...  )
How much room do you have between the top of intake and bottom of deck lid, I have a Trailblazer ss intake, I'd like to use, but just don't know until I can mock it up. (i know they're ugly but are the best of the oe cathedral port intakes...)
Joe
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fieroguru
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MAY 27, 11:00 PM
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Maybe an inch:
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motoracer838
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MAY 27, 11:21 PM
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So much for that idea, thanks...
Joe
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fieroguru
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MAY 28, 10:38 AM
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| quote | Originally posted by motoracer838:
So much for that idea, thanks...
Joe |
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Don't get overly hung up on ideal LS based parts, there are very, very few truly bad parts (stock LS4 intake would be one). The LS1, LS2, LS6 intakes have all been used on 500hp NA builds... so while a dyno will show the TBSS being about 30 lb-ft and 30 hp better than the LS1 on a 6.0L engine spinning to 7K, the difference will be less with the 5.3.
With fieros and available manual transmissions, having some slight reduction in low RPM torque isn't a bad thing.
Focus on what fits, looks good, and is less expensive (which is why I run the LS2 intake).
I could swap to a non-dod camshaft and port the LS2 intake and be over 400 whp...
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motoracer838
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MAY 28, 01:40 PM
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Just happened to have it on hand for my Silverado, if I ever get to it...
My plans are as follows, tell me if you see a problem with any of it. The engines I'm looking at tomorrow are all '06, that gives me the 24x reluctor
Dod delete
Mild cam, possibly a used LS3 or 6 cam
LS2 or 6 intake with a drive by cable tb
0411 pcm, probably start with a stick shift LS1 tune for a starting point, this "should" work for Colorado smog laws, I'll know more tomorrow!!!
and a decent exhaust, probably take a page from your book with the LS7 manifolds, I to have had issues with "shorty's" And I don't feel like building headers for this...
I'll spend the money where I have to and be cheap when I can...
With nearly 300 ft lbs of torque at just over 2000 rpm's yours must be an insane amount of fun to drive... 
Joe[This message has been edited by motoracer838 (edited 05-28-2018).]
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