I have searched the posts and I can not find a definitive configuration for this conversion. If converting a 2.8L to a 3.1L(turbo after engine break-in), exactly what components are required? I have two engines right now. One new crate motor (0 miles, 2.8) and one rebuilt 2.8L (shortblock)with a 3.1 crank and dished pistons and Compucam 2030(?) cam. I want go with the 3.1 with the new top end on the rebuilt bottom end. Will I need an adjustable fuel regulator, also? How do I know if this is necessary? How does one determine how much to adjust the fuel pressure? Is it simply trail and error?
Any other suggestions on the two engines? Should I stay with the stock 2.8 (maybe Compucam only) and use this for the turbo setup or go for the maximum and use the rebuilt 3.1. I am concerned about the compression ratio increase. PLEASE HELP!!!!
You have a couple of questions that require a bit more info before a good answer can be given. First off how much boost are you planning to run with your turbo setup. I run 12:1 compression with 9psi boost on a supercharger and stock engine components (2.8). Than you are talking about fuel pressure increase when you really should be talking about fuel volume increase. So a fuel pressure rise will do you no good because you have MAP sensor as opposed to a MAF sensor. You have to adjust the VE tables to get the engine running properly. Don't forget that your engine is runing like a stock engine when at Idle since there is no boost created and whatever small pressure is created it's probably thrown overboard via the pop off valve. You have to play with the VE tables at higher rpms. Design one has a turbo setup Chris West TerryK can help you with it they have done reprogrammings.
Later
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12:41 AM
onfire Member
Posts: 1560 From: Maple Valley, WA Registered: Oct 2000
Originally posted by Cplensdorf: I have searched the posts and I can not find a definitive configuration for this conversion.
You and me both, however it looks like you are a lot further in the planning stages than I have managed to get. So far all I have is a set of 3.1L Silvolite pistons (part# 1486).
I'll be anxious to see if anyone else has compiled a parts list (I'm just starting mine).
I'd make sure the CR in the rebuilt engine is under 9:1 or so for a performance turbo installation. If you are building a turbo system from scratch, I'd suggest buying a Stage II management system from Design One as a starting point. It's computer will at least understand what boost is, and fiddle with injector pulse width and ignition timing to accommodate boost. You could use an adjustable fuel regulator (I bought one) to make small adjustments to fuel delivery, and/or a rising rate unit added in to get even more fuel. You'll probably need a high volume pump with this stratedgy. You adjust fuel pressure with a guage attached to the guage port, on the right hand side of the fuel block. I don't think an adjustable regulator is sufficient by itself to keep a turbo engine alive. You'd probably scatter the engine before you knew anything was wrong. 1)--Read the books "Maximum Boost" and "How to Select and Install Turbochargers". 2)--Talk with the folks at Design One. Just my $.02 worth.
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05:56 PM
Cplensdorf Member
Posts: 663 From: Grass Lake , MI Registered: Nov 2000
Thank you all for the advice. I have decided for various reasons to build the 3.1. I was told by Kevin at Design I that the stock injectors and fuel system has been tested with their Stage I system. Exactly what I was looking for. Does anyone know what I should expect out of the nat. aspirated 3.1 and Compucam upgrade. Will their be a seat-of-the-pants difference?
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08:56 PM
rogergarrison Member
Posts: 49601 From: A Western Caribbean Island/ Columbus, Ohio Registered: Apr 99
I would suggest that you keep the comp. lower than 9.0:1 as well. I have have heard several horror stories about 3.1 V6's with 9.0:1 comp. crushing the second piston landing on the number 5 piston using the turbo set-up.
------------------ Dave Gunsul N.I.F.E. member 86 GT modified 85 SE daily driver
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05:07 PM
Apr 16th, 2001
Cplensdorf Member
Posts: 663 From: Grass Lake , MI Registered: Nov 2000
Unfortunately I can't get a hold of most of these people becuase I read a few in old issues of F.O.C.O.A.'s newsletter that my clubs membership director had lent me. But, the guy you should talk to has built a custom turbo 3.4 that he designed himself for his 86-87 GT!! I don't know if he's on this forum but I do know he reads the Fiero list, so you might want to post something their. sorry I can't remember his name. Anyone else know who I'm talking about that knows his name??
------------------ Dave Gunsul N.I.F.E. member 86 GT modified 85 SE daily driver
BTW i didn't mean this guy actually designed his own turbo, he used a Ford turbo. He has a web page too but I'll be damned if I can remember the address either. I must be losing my mind.
------------------ Dave Gunsul N.I.F.E. member 86 GT modified 85 SE daily driver
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10:09 PM
Apr 17th, 2001
Voytek Member
Posts: 1924 From: Calgary, Alberta, Canada Registered: Jan 2001
Cplensdorf - I just had my 2.8 rebuilt to a 3.1 and only have about 800 miles on it since rebuild (if I understand correctly, that's what you're trying to do). I have 3.1 crank, pistons and performance cam. The answer is NO: there is no seat-of-the-pants difference, BUT there IS a significant difference from the stock 2.8. I haven't revved it real high yet (only 3500 so far) and haven't floored it yet but it feels VERY strong. From 35 MPH to 60 MPH I actually kept up with a supercharged T-bird. Naturally that car was much heavier with 3 people in it but it still felt pretty good. To make a long story short, yes, there is a definite difference over the stock 2.8 but it's not neck-snapping. (oh yeah, I also put the Sprint manifolds on mine and I think that helped a bit too)
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03:22 PM
Cplensdorf Member
Posts: 663 From: Grass Lake , MI Registered: Nov 2000
Voytek - What cam did you use? I am using the CompUcam 2030(?). Does the stroke and cam change make a difference in the sound of the engine? Did you do any porting? Head work?
Originally posted by Dave Gunsul: "...But, the guy you should talk to has built a custom turbo 3.4 that he designed himself for his 86-87 GT!! I don't know if he's on this forum but I do know he reads the Fiero list, so you might want to post something their. sorry I can't remember his name. Anyone else know who I'm talking about that knows his name??"
Cplensdorf - the cam they put in my car is a Federal Mogul. I have no idea if this is a good name or not but the engine rebuilders who did my car seem to think it's a pretty good cam. To answer your other questions, no, it does not make a big difference in the sound. In fact, the car seems to run smoother and therefore quieter (I was hoping it would sound more aggressive). It definetely feels very smooth on the highway. Most of the power difference that I noticed is in the 2000-3000 rpm (I haven't had it past 3500 yet). The heads were completely remanufactured and shaved to get more compression but no porting work was done. If I had to do this over again, I'd probably put an aluminum head 3.1 from another GM in my car. I've seen a Fiero run one of those and the power increase seems to be a lot more than just boring out the stock 2.8. The only drawback is no more stock look (can't change over the intake plenum).
YES!! YES!! That's the guy!! Thanks Frogpuf. Take a look at Dennis's turbo page it should answer ALL your questions and if not you can email him, he's very knowledgeable about turbos and should be able to help you.
Thanks again Frog.
------------------ Dave Gunsul N.I.F.E. member 86 GT modified 85 SE daily driver
