When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
91 firebird
0.040" over 350
10:1 comp --> hence E85
215 cc intake Dart Iron Eagle Heads, 64 cc chambers
Victor Jr intake (being changed from Performer RPM)
650 holley dp that's going to be modified for blowthrough and E85 by me
Clevite flat solid cam ~0.530" lift ~240* duration @ 0.050" 110 lsa --> not optimal but it is much milder than the specs show and besides swapping the cam is more $
T56
centerforce DF
Goofy GT4094/GT4294 turbo from a CAT C12 68/94 comp 82/75 turbine with a 1.28 a/r T4 turbine housing swapped onto it --> certainly the compressor is too small but for free who cares
JGS 50 mm wastegate
RPS 50 mm BOV
stock manifolds
Mallory 4309 reg
Walbro 417 lph E85 pump
the manifolds to turbo is almost complete just need to finish the merge. Shown is last Saturdays progress, project progress should continue this weekend. Oh yeah don't bust my ***** about the turbo support, it is temporary and will be completed after the wastegate is fabbed in. In it's present state it is probably the worlds worst support..haha
Last edited by zacharyhorn; 03-10-2014 at 08:21 AM.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
This is a budget build and we are working with what I have. Here are some more pics of this weekend's progress. We only have about 3 days of work into it as of now.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
I plan on eliminating the a/c and tensioner brkt. I will make a slotted bracket that will bolt to the alternator bracket (toward center of engine) that will allow the alternator to rotate and become the mechanism of adjustment. It is not complete but I have made something similar in the past. However this will mean that the grooved side of the belt will be riding on the smooth water pump pulley. Since only the pump is being driven off that pulley (not a mech fan) I believe it will work fine with out slip and the shoulders on the pulley will keep the belt from walking off. Hope my crappy explanation clears things up. I will post up pics when I make the bracket.
edit: I will have to change to a standard rotation water pump as well.
Im of the opinion that the compressor is too small, but we will see. Need to further research compressor upgrades, damn GT series screw on comp wheels.
Since this will be running on E85, I plan on running 10-15 PSI as it sits. What do you guys think this combo will do once everything is ironed out? And everything will clear the factory hood and you cant even see the exhaust. Going for a sleeper look.
Last edited by zacharyhorn; 03-10-2014 at 08:39 AM.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
You might be alright with that comp wheel, run it and find out. If it's a dog, turn the boost up! Upgrade to a 7675 precision or a PT88 when the funds allow
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
That 650 carb may b a touch too small for 600hp on e85.
Spraying water/meth will help to get to that HP level. I'm a big fan of pre compressor injection.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Originally Posted by zacharyhorn
I'm hoping to push it to 600-650 HP at higher boost levels. I'm hoping that's possible. It's been a learning experience thus far, that's for sure.
the ebay gt45 will do 600 on a 350 , so even though the turbo u have is slightly smaller then the ebay gt45 it should get u to about the same point as id expect it to be a lil more efficiant then the ebay unit
also if this is ur first turbo build , ur more then likley going to nuke the engine before u hit the limit of that turbo
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Nothing much to update. We've got the car running pretty well and I've been beating / driving it quite a bit. Running 10-12 LBS of boost with my combo on 22 degrees timing locked out. Still runs pretty fat up top at 10.8 - 10.9 AFR at WOT. I have some tricks I'm going to try soon to get that a fuzz leaner. It misses up top due to my weak ignition and being rich. Here are a few recent pics.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Originally Posted by Jay_rich
Awesome, very similar placement to mine. I mounted mine staight which is causing filer issues. But was easier to fit with the LS motor.
Jay
Cool! This was the N/A motor I built and went turbo with. The compressor is a little small but it pulls like a train. I need to lean out the top end a bit. I'm at 10.8-10.9 right now. Finally got the curve flat. Now I'm just going to trim the pitot tube in the hat. See what happens.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Thanks guys. I learned a lot along the way. I still have a few things to do as far as bracing and exhaust hangers, but I've been driving it all over the place in the meantime.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Thanks i just noticed our engines are pretty similiar. I also have dart 215 and a victor jr and a big solid na cam and a lil less than 10.1 just cubic inch difference. I almost ditched the darts because of the adj guideplates i was so sick of deeling with them i finally put a tac on each guideplate and now they wont move. That turbo must spool like crazy with that healthy of a motor pushin it!
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Originally Posted by 86trbota
bitchin job on the carb hat! should be a burnout machine!
Thanks man! 1st and 2nd gear are worthless. Third spins to about 60-70 mph and moves out!!! I'm hoping to hit 140 mph at the track with it at 12-13 psi next spring.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
140 on 12-13 psi would be doing extremely well. I think it will take more boost but depends how aggressive you get on the tune with e85. It makes alot more power than pump gas
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Well, I have a small update. The build is going to go in a different direction. My buddy talked me into purchasing a Garrett GTx4508R. This is a much better suited turbo for my current engine combo than my previous GT4094/4294 turbo. I'll be getting started bolting it on and getting all the lines plumbed in and ready to tune. My buddy will be doing the blow through carb mods for the E85 conversion. I'm really excited to see how this turns out.
Re: 1991 Firebird Turbo Build Thread - Garrett GT4294 Single Blow Through
Almost time to bolt this bad boy on. It's a Garrett GTX4598R. Should be a SIGNIFICANT increase from the 4094/4294. Just needs to warm up a bit up here.
03-10-2014, 08:15 AM
