chevy l.s. engine swap vs good old ford power

Scott_AZ · Post by **Scott_AZ** » Wed Mar 22, 2017 9:44 am

black954 wrote:Are the autofab engine mounts solid or poly? I'm in a similar situation dropping an LS3 into my bronco and Don't really know if I should solid mount the trans and motor or use poly mounts. Looks like all the trophy trucks use engine plates but that's not really a good comparison.

They're poly like spring bushings. At first, I was like "I can build these!" But after doing the driver side, there's no way it would be worth the time:$ ratio. You could do a midplate and get away with the complexity of the normal bottom mounts. I've never run a midplate engine mount personally, but I'd want the front braced too. I've had a TH400 bellhousing rip clean off so I have this phobia about cast and mounting. I don't know...

black954 · Post by **black954** » Wed Mar 22, 2017 11:47 am

Thank you, that makes sense. I'm building a similar combo as you are and you've had some good ideas. I'm running an LS3 with a TH400 and Atlas II. The TH400 has a LS Super Bell housing so hopefully that eliminated the weak bellhousing. I think i'm going to go with similar poly motor mounts, poly trans mount, and then build a separate crossmember for the Atlas II with poly mounts. I'm kind of scared running a motor plate or mid plate with an aluminum block. Plus my long term plans are to add a 4.0L Whipple and doubling the HP which will increase the stress on the motor.

philofab · Post by **philofab** » Wed Mar 22, 2017 12:40 pm

I see more broken bellhousings in motor plate trucks than I do on regular trucks with rubber/poly motor mounts and trans mounts.

Most broken transmissions are from a broken crank, bent driveline, or broken flexplate.

black954 · Post by **black954** » Wed Mar 22, 2017 2:29 pm

That's good information there. I swapped out the OEM flexplate for a HD SFI Circle D flexplate to hopefully eliminate that weak link.

XTate · Post by **XTate** » Wed Mar 22, 2017 8:29 pm

We need photos of these LS builds, maybe a separate thread or sections just for LS real fast Broncos, the Fox body guys have been doing them for years, we need to catch up, it would be great to have all the info in one spot. Tate

Scott_AZ · Post by **Scott_AZ** » Wed Mar 22, 2017 11:23 pm

Not really much to see yet in my opinion. You could imagine tearing out a 5.0 and trans - bare engine bay and some degreasing. Then I cut the old engine mounts out and bolted the new stuff in. Then I bench fired the engine to make sure it wasn't knocking or clacking. It'd been sitting (in good care) for around 6 or 7 years. I got the engine in the bay today. There's a bunch of personal BS in here, but it has some pics and stuff attached to the build. https://www.instagram.com/sonoranguy/

My TH400 broke from shortcourse abuse. I hucked it at about 80mph on the second jump on the front straight @ firebird. I don't know anything about midplates. They make sense when you're full tube chassis. How do the buggy dorks secure their engines? I remember sitting on the back of a schoolbus getting punted over speed bumps and train tracks as a kid, I'd guess an engine on the back of a class 1 gets punted pretty hard too!

black954 · Post by **black954** » Thu Mar 23, 2017 5:22 am

I'm kind of at the same point. Degreased engine bay, LS3 on a stand, still gathering last parts to put it in. Plus mines an 81' so I want to box my frame before I put the drivetrain in. I will start a build thread once I get back on it. I moved houses and am building a big garage currently. Once I get the electric run to the garage, I will be right back on the Bronco.

Tchajagos · Post by **Tchajagos** » Thu Mar 23, 2017 8:43 am

Sweet! I have its twin here except it's an 82. I like the letters in the hood and the 81 grill better though. Not a fan of the holes in the frame on the 81 haha.

black954 · Post by **black954** » Thu Mar 23, 2017 10:59 am

wow, thats crazy lol. I do like the front end best on the 80-86 years and the FORD letters. It's a shame I am forced to swap to the 92-96 front end to get glass wide enough for what i'm doing.

BajaBronco13 · Post by **BajaBronco13** » Thu Mar 23, 2017 11:57 am

black954,

Autofab sells a set of 1980-86 3.5" wider fiberglass fenders. No need to move to 92-96 if you don't want to.

Chris

Tchajagos · Post by **Tchajagos** » Thu Mar 23, 2017 12:22 pm

black954 wrote:wow, thats crazy lol. I do like the front end best on the 80-86 years and the FORD letters. It's a shame I am forced to swap to the 92-96 front end to get glass wide enough for what i'm doing.

Where are you located? Want to sell the hood/grill?

black954 · Post by **black954** » Thu Mar 23, 2017 12:26 pm

I'm in Chicago, IL I would totally sell the whole front end but I dont think anyone would want to pay shipping

black954 · Post by **black954** » Thu Mar 23, 2017 12:29 pm

BajaBronco13 wrote:black954,

Autofab sells a set of 1980-86 3.5" wider fiberglass fenders. No need to move to 92-96 if you don't want to.

Chris

I did see those as an option. I'm just not sold on the look of them yet. I will be running a full soft top too so i'm kind of concerned with how it will all look together when it's all done. When I get closer to body work, I will look into them much better. Good advise, thank you

XTate · Post by **XTate** » Thu Mar 23, 2017 11:42 pm

God that atlas looks sweet. Why did you go with the 400 vs 4L80? Tate

black954 · Post by **black954** » Fri Mar 24, 2017 5:16 am

Mostly cost reasons. I have only $2200 into a 1500HP rated TH400 and the 4L80 would have been more then double that. Plus the torque converters are cheaper. If my Bronco was going to do a lot of street driving I would have gone with the OD, but I'm building it for 80% dunes and 20% cruising and car shows. I think my build differs a lot from the normal trucks on this site. You guys build near trophy trucks to withstand 1000's of desert miles and some are even street trucks. For my purposes, I want a lot of power, lower weight, and stability in the sand. They are kind of similar but there will be differences in the small details. If I could get my Bronco under 5,000lbs, I would be very very happy.

Scott_AZ · Post by **Scott_AZ** » Fri Mar 24, 2017 1:52 pm

Looks awesome man. I highly recommend the autofab mounts. $400 and change is a lot for what they are, but after putting them in, I wouldn't try to do it any other way. The driver's side is a total pain. I trimmed the old mount with the plasma and grind and hammer off the rivets. I used to have a black 86 bronco but it had way over 200k miles on it and the rivets were coming loose. I traded it for my tow rig I have today and have no regrets. I really liked that body style. The one I'm doing the swap in now is an '88 and it's my least favorite body style. When I do fiberglass on the front, I'm considering either a 1 piece or change to the late 90's style front end.

V-band exhaust... 1500HP TH400... You planning to boost that LS3?

black954 · Post by **black954** » Fri Mar 24, 2017 2:23 pm

The Autofab mounts would need to be altered so I am going to make my own mounts using poly leaf spring bushings. Everything they make is top quality for sure. And I might wind up using Autofab glass if I keep the 81' front end. I'm not a huge fan of the brick nose either, but I do like the last gen bodystyle too. Yes, I plan on adding a 4.0L whipple to the LS3 after I get the suspension all done. Won't be for a few years. I just would rather pay to have the trans built to handle the power now then send it out later. I am building from scratch so it's hard to cut corners on something that will eventually need upgrading later. Plus i'm trying to over build as much as I can cause the stress on components from the weight of the Bronco combined with a lot of HP. I have to explain myself every time I order go fast parts cause most people only know drag racing. The V-bands are more for vibration. I will build long tube headers when I boost it. I can cut the V-bands off and save them so it's not really money out the window, or at least that's what I tell the wife lOl

mobil1syn · Post by **mobil1syn** » Thu Mar 30, 2017 11:22 am

http://www.gmperformancemotor.com/parts/19257230.html

for the CA guys. came a crossed this last night. CARB approved, good power for a reasonable cost.

Needles929 · Post by **Needles929** » Fri Feb 23, 2018 12:50 pm

Read through this thread today. Any updates??

VintageIronFab · Post by **VintageIronFab** » Sun Feb 25, 2018 1:09 pm

I still don’t understand why not just drive a Chevy and put beams under it- just seems like a whole lot better of an idea but maybe that’s just me dunno