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LS4 question.. by GT86FASTBACK
Started on: 04-04-2014 02:50 PM
Replies: 9 (440 views)
Last post by: fieroguru on 04-06-2014 08:55 AM
GT86FASTBACK
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Report this Post04-04-2014 02:50 PM Click Here to See the Profile for GT86FASTBACKClick Here to Email GT86FASTBACKSend a Private Message to GT86FASTBACKEdit/Delete MessageReply w/QuoteDirect Link to This Post
Does the FWD LS4 engine have the same Bell bolt patter as lets say an rwd LS1???
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Fiero84Freak
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Report this Post04-04-2014 04:00 PM Click Here to See the Profile for Fiero84FreakClick Here to Email Fiero84FreakSend a Private Message to Fiero84FreakEdit/Delete MessageReply w/QuoteDirect Link to This Post
No.

The LS1 utilized in RWD applications (think C5 Corvette, 4th Gen F-body, etc) uses a 90 degree bolt pattern, same as the standard SBC that's beyond common. The LS4 used in FWD applications uses the common bolt pattern seen on most GM FWD applications.
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fieroguru
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Report this Post04-04-2014 04:39 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
No. The LS4 has the GM Metric pattern - same as the Fiero uses. The LS4 block is about 3/16" Longer than the RWD blocks as the bellhousing pattern was raised to clear the bolts holding on the rear cam cover. The LS4 crankshaft is shorter than the RWD versions by about 14mm about 4mm on the bellhousing side and 10mm on the accessory side.

The interesting part is the RWD dowel pin locations are drilled in the LS4 block, even though they are not needed or used.

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jscott1
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Report this Post04-04-2014 10:23 PM Click Here to See the Profile for jscott1Send a Private Message to jscott1Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Fiero84Freak:

The LS4 used in FWD applications uses the common bolt pattern seen on most GM FWD applications.


You would think that since the LS4 bolts up to Fiero transmissions that the swaps would be more common? But alas Fiero auto transmissions are garbage, and bolting an LS4 to a manual is apparently problematic. I'm speaking observationally, as don't see many running LS4 swaps and wondering why.
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dratts
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Report this Post04-05-2014 03:49 AM Click Here to See the Profile for drattsClick Here to Email drattsSend a Private Message to drattsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jscott1:


You would think that since the LS4 bolts up to Fiero transmissions that the swaps would be more common? But alas Fiero auto transmissions are garbage, and bolting an LS4 to a manual is apparently problematic. I'm speaking observationally, as don't see many running LS4 swaps and wondering why.


Makes sense to keep the ls4 with its transmission. You can't get a stronger transmission that I know of. Although I've broken three input shafts with mine I believe that a 300m shaft on a stock ls4 would work and 300 hp in a Fiero is far more than adequate.
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fieroguru
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Report this Post04-05-2014 07:42 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jscott1:
You would think that since the LS4 bolts up to Fiero transmissions that the swaps would be more common? But alas Fiero auto transmissions are garbage, and bolting an LS4 to a manual is apparently problematic. I'm speaking observationally, as don't see many running LS4 swaps and wondering why.


The number of LS4 swaps continues to increase, but most are coming out of shops vs. DIY. Fieroking is up to 4 (or 5) completed LS4 swaps, Darth Fiero has completed 2, Fiero Addiction completed 1 (or possibly 2), Archie has completed 1 as well, and I don't know how many WCF has completed, but I have seen pictures of at least 2. All of these Vendor swaps were LS4/4T65/hd.

There are probably another 7-10 DIY LS4 swaps currently in the works, but it isn't a simple swap and takes time.

The wiring aspect of the LS4 is pretty significant and many people are scared of the DBW or DoD. Of the completed DIY ones that I am aware of, 3 switched to aftermarket ECMs and run a cable throttle and 2 kept the stock ECM/DoD and DBW. There are probably a few more out there that I just haven't come across.

There are only 3 running LS4/Manual swaps (MWhite, fieroguru, Kemp3) that I am aware of, largely due to the need for a custom flywheel and starter mount. Later this year, both of these will be available from me for the LS4/F40, so that should start to increase the popularity of the swap. Most Fiero people tend to want bolt together options for their swaps and right now the LS4/manual isn't that easy.

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[This message has been edited by fieroguru (edited 04-06-2014).]

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GT86FASTBACK
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Report this Post04-05-2014 09:59 AM Click Here to See the Profile for GT86FASTBACKClick Here to Email GT86FASTBACKSend a Private Message to GT86FASTBACKEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ok, just figured I would ask. Was kinda curious.
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jscott1
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Report this Post04-05-2014 01:10 PM Click Here to See the Profile for jscott1Send a Private Message to jscott1Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:


The number of LS4 swaps continues to increase, but most are coming out of shops vs. DIY. Fieroking is up to 4 (or 5) completed LS4 swaps, Darth Fiero has completed 2, Fiero Addiction completed 1 (or possibly 2), and Archie has completed 1 as well. All of these Vendor swaps were LS4/4T65/hd.

There are probably another 7-10 DIY LS4 swaps currently in the works, but it isn't a simple swap and takes time.

The wiring aspect of the LS4 is pretty significant and many people are scared of the DBW or DoD. Of the completed DIY ones that I am aware of, 3 switched to aftermarket ECMs and run a cable throttle and 2 kept the stock ECM/DoD and DBW. There are probably a few more out there that I just haven't come across.

There are only 3 running LS4/Manual swaps (MWhite, fieroguru, Kemp3) that I am aware of, largely due to the need for a custom flywheel and starter mount. Later this year, both of these will be available from me for the LS4/F40, so that should start to increase the popularity of the swap. Most Fiero people tend to want bolt together options for their swaps and right now the LS4/manual isn't that easy.


Thanks for the technical explanation... an LS4/F40 sounds pretty nice to me, but I guess most folks would just rather use the adapter plate and LS3. But something about adapter plate swaps just don't look right to me. Yes, 300 hp is more than enough in a Fiero... I'm not trying to be the fastest, just a nice upgrade. Are you planning a kit, or a turn-key or both?

[This message has been edited by jscott1 (edited 04-05-2014).]

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iluvsd619
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Report this Post04-06-2014 01:28 AM Click Here to See the Profile for iluvsd619Click Here to Email iluvsd619Send a Private Message to iluvsd619Edit/Delete MessageReply w/QuoteDirect Link to This Post
I paid $1000 for my ls4. It has 15k on it! Its an inexpensive way to have LS power. Can't wait to finish mine! An LS3 is great, but it's about $5000.00 for a used motor.


Thanks for the technical explanation... an LS4/F40 sounds pretty nice to me, but I guess most folks would just rather use the adapter plate and LS3. But something about adapter plate swaps just don't look right to me. Yes, 300 hp is more than enough in a Fiero... I'm not trying to be the fastest, just a nice upgrade. Are you planning a kit, or a turn-key or both?

[/QUOTE]

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fieroguru
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Report this Post04-06-2014 08:55 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by iluvsd619:
I paid $1000 for my ls4. It has 15k on it! Its an inexpensive way to have LS power. Can't wait to finish mine! An LS3 is great, but it's about $5000.00 for a used motor.


I paid $1000 for my 18K mile LS4 w 4T65e-hd and sold the transmission and other unused parts to help offset the cost. In a Fiero the base LS3 dynos around 390 to the wheels and my LS4 with some bolt ons (Cam, LS7 MAF and exhaust manifolds, LS2 TB & Intake - roughly $1400 spent on the upgrades) dyno'd 382 whp @ 6800 rpm... these were on different dynos so an exact comparison can't be made, but if you are willing to spin the LS4 to offset the loss of displacement, you can make comparable power to the stock LS3 (and they can cam it to make even more).
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