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LS4- F40 performance question by cam-a-lot
Started on: 07-24-2018 07:34 AM
Replies: 3 (222 views)
Last post by: cam-a-lot on 07-24-2018 05:24 PM
cam-a-lot
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Report this Post07-24-2018 07:34 AM Click Here to See the Profile for cam-a-lotSend a Private Message to cam-a-lotEdit/Delete MessageReply w/QuoteDirect Link to This Post
I was chatting with a corvette owner recently about some of the V8 swaps that have gone into Fieros.

He was wondering about actual performance numbers of LS4/F40 trans in a Fiero. I don't know anyone with this combo here locally, but does anyone have actual 1/4 mile and dyno numbers for some of these swaps? This guy has deep pockets and is thinking of finding a Fiero with this combo and wants some more info on it.

I would assume the F40 can take the beating a lot better than the Getrag tranny bolted to the more old school V8 Archie style swaps if driven hard?

Hope to see some of these cars at the 35th.
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J Gunsett
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Report this Post07-24-2018 08:32 AM Click Here to See the Profile for J GunsettClick Here to visit J Gunsett's HomePageClick Here to Email J GunsettSend a Private Message to J GunsettEdit/Delete MessageReply w/QuoteDirect Link to This Post
The one to talk to is Fieroguru, he has had his down the track many times. Hope to see you at the 35th and if you want a ride in a LS3 car you got it.

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fieroguru
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Report this Post07-24-2018 12:38 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
The LS4/F40 combo is quite rare. With mine and the 2 others I have helped that have running swaps, we are at 3. I assume WCF has done a few, but we are still likely less than 10 running LS4/F40 swaps world-wide at this point. There are at least twice that currently in progress, so the numbers will continue to climb, but the rate has been slow. It has been 5 years since the first one was completed.

The LS3/F40 swap is far more common. So if you friend was looking to buy a swap used, that is likely what he could find.

My LS4 has been warmed over and has about 420-430 flywheel hp and 382 rwhp (or about 120-130 more hp than the stock 303 fwhp)


Within the first 6-7 months of the swap, I ran 12 1/4 runs in 2 days at LSFest. It was there I found an issue with the chift cable buckling going into 3rd, so my best was 12.8 @ 114 on a 90ish degree day. I have been down the 1/4 mile 1 time since on the HRPT, but it was about 100 degrees and sprinkling... so it wasn't a contender.

With the right wheels/tires, more ideal conditions (70 degree temps), and a few other tweaks to shift the focus to 1/4 mile times. I could likely get the car into the low 12's and maybe tap on 11.99... but that really isn't the purpose of the car. It is more a pro-touring setup with a more balanced approach vs. biasing for 1/4 mile. I like to autocross the car a lot more than drag race it.

If you really want to optimize 1/4 mile times, run an auto.

The swap has been done for 5+ years, logged 46K miles, with the only two issues being the shift cable buckling (resolved in year 1), and the belt tensioner broke twice - about 3 years apart, so I made a billet aluminum one in 2016. It normally gets between 17-20 mpg on fill ups with mostly in town driving. With a mix it normally sees 24, with dedicated interstate is can see 27-29 mph @ 80 mph @ 2100 rpm (thanks to the 3.09 final drive swap).

To quote Ferris Bueller...
"It is so choice. If you have the means, I highly recommend picking one up."
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cam-a-lot
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Report this Post07-24-2018 05:24 PM Click Here to See the Profile for cam-a-lotSend a Private Message to cam-a-lotEdit/Delete MessageReply w/QuoteDirect Link to This Post
Great info- thanks!
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