LS4 Fiero Turbo Build
LS4 Fiero Turbo Build My buddy and I are in the planning phase of putting a turbo on our LS4 Fiero. Just looking for general input from turbo gurus if there is something messed up with our plan. Already we have put quite a lot of thought into this. Our limitation is the transmission. We have put as many parts into it that are available, but it is still limited to 450-500TQ because of the chain. So our plan is to control the boost to optimize 500TQ for the entire RPM band reaching 600HP at 6300rpm. So this is a mild build because of this limitation and we will be dumping a lot of boost.
Normally aspirated current setup: Car ran 1.7 60' 11.7@116mph on street tires we estimate 420HP right now, weighs 2500#
LS4 / built 4T65E-HD / cam 224/227 117 / ls6 hand ported heads / TBSS intake, rails, TB / Walbro 255
Turbo parts list:
2 bar MAP for SD tune with HPT
42# truck injectors (already purchased)
Racetronix regulator with boost reference returnless (currently using vette regulator)
XS Power 60mm BOV
Precision PW46 wastegate
Air to water IC generic (engine is in the back!)
Cortex boost controller with gage (this seems ideal can control boost by RPM and gear)
Innovate LC-2 WB and gage
Turbowerx scavenge pump (turbo will be mounted low, off the stock manifold, so it can't really drain)
Generic ebay/amazon GT45 turbo
Normally aspirated current setup: Car ran 1.7 60' 11.7@116mph on street tires we estimate 420HP right now, weighs 2500#
LS4 / built 4T65E-HD / cam 224/227 117 / ls6 hand ported heads / TBSS intake, rails, TB / Walbro 255
Turbo parts list:
2 bar MAP for SD tune with HPT
42# truck injectors (already purchased)
Racetronix regulator with boost reference returnless (currently using vette regulator)
XS Power 60mm BOV
Precision PW46 wastegate
Air to water IC generic (engine is in the back!)
Cortex boost controller with gage (this seems ideal can control boost by RPM and gear)
Innovate LC-2 WB and gage
Turbowerx scavenge pump (turbo will be mounted low, off the stock manifold, so it can't really drain)
Generic ebay/amazon GT45 turbo
TECH Enthusiast
Joined: Dec 2017
Posts: 676
Likes: 72
I did this on a buddies lambo kit car. We mounted the turbo over the trans bellhousing. Any way id go 7875 turbo if i was you. The gt45 is a good turbo but they are pretty damn big. The 7875 is better and is a much smaller external demension.
On The Tree
Joined: Jul 2013
Posts: 196
Likes: 55
[QUOTE=00PewterSS;20192837]My buddy and I are in the planning phase of putting a turbo on our LS4 Fiero. Just looking for general input from turbo gurus if there is something messed up with our plan. Already we have put quite a lot of thought into this. Our limitation is the transmission. We have put as many parts into it that are available, but it is still limited to 450-500TQ because of the chain. So our plan is to control the boost to optimize 500TQ for the entire RPM band reaching 600HP at 6300rpm. So this is a mild build because of this limitation and we will be dumping a lot of boost.
I think this guy beat you to it:
https://ls1tech.com/forums/forced-in...l#post20186697
I think this guy beat you to it:
https://ls1tech.com/forums/forced-in...l#post20186697
Ha!
I believe we may have had the engine in our car first
No idea who's was running first. And from this https://ls1tech.com/forums/conversio...d-swap-16.html it looks like he has a bit of a delay rebuilding the motor. We also have a 4T65E-HD where he is using a manual trans that I do not know for certain the limitations. Our car is lighter and has patina... also has a roll bar we put in last year.
As for the GT45 vs 7875... I didn't know they were that different in size. We will need to check that out. The GT45 is very cheap and it seems pretty suitable for this. Did this fake lambo have a 4T65E-HD... what other details you have... power? Has it blown up yet?
I believe we may have had the engine in our car first
No idea who's was running first. And from this https://ls1tech.com/forums/conversio...d-swap-16.html it looks like he has a bit of a delay rebuilding the motor. We also have a 4T65E-HD where he is using a manual trans that I do not know for certain the limitations. Our car is lighter and has patina... also has a roll bar we put in last year.As for the GT45 vs 7875... I didn't know they were that different in size. We will need to check that out. The GT45 is very cheap and it seems pretty suitable for this. Did this fake lambo have a 4T65E-HD... what other details you have... power? Has it blown up yet?
Glad to see another Fiero going the turbo route!
I should have mine done by the 2020 HRPT, but it really depends on other scope creep.
My LS4/F40 first start was Feb 10, 2013. There were probably 5 or so other running LS4 swaps at that time, I definitely wasn't the first.
I should have mine done by the 2020 HRPT, but it really depends on other scope creep.
My LS4/F40 first start was Feb 10, 2013. There were probably 5 or so other running LS4 swaps at that time, I definitely wasn't the first.
TECH Enthusiast
Joined: Dec 2017
Posts: 676
Likes: 72
It had an sbc not an ls. We actually used an ebay 76mm turbo for it. It had the sbc adapted to the fiero 5 speed. It was cool but when we turned it up the little clutch would **** pretty quick. I figured it would be close to the same set up as yours. We may have had more room due to the engine cover or "hood" being modified.
The gt45 is the same size physically as a borg s475 or close to it. There should be some pics on her comparing an s475 to a 7875. Youll be super suprised i think.
The gt45 is the same size physically as a borg s475 or close to it. There should be some pics on her comparing an s475 to a 7875. Youll be super suprised i think.
Your car was definitely running first. Our car has been completely rebuilt, except the body. We haven't touched the body and it isn't exactly pretty.... so your car wins the beauty contest! Our car is 2684# actually with the roll bar in it.
If you don't mind can you send me your parts list plan? Do you know how much that F40 can take? Details about the brake conversion as well? You can send via IM... appreciate any info that we can learn from your experience.
Any other feedback from 5.3 mild turbo builds?
If you don't mind can you send me your parts list plan? Do you know how much that F40 can take? Details about the brake conversion as well? You can send via IM... appreciate any info that we can learn from your experience.
Any other feedback from 5.3 mild turbo builds?
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It had an sbc not an ls. We actually used an ebay 76mm turbo for it. It had the sbc adapted to the fiero 5 speed. It was cool but when we turned it up the little clutch would **** pretty quick. I figured it would be close to the same set up as yours. We may have had more room due to the engine cover or "hood" being modified.
The gt45 is the same size physically as a borg s475 or close to it. There should be some pics on her comparing an s475 to a 7875. Youll be super suprised i think.
The gt45 is the same size physically as a borg s475 or close to it. There should be some pics on her comparing an s475 to a 7875. Youll be super suprised i think.
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