Aaron's 3.4 DOHC 88GT Build Thread

[Aaron]

It seems I have like 5 threads associated with my swap, so from now on this will be the one and only. The admin can delete the "I'm XXX poorer and one step closer thread." I have not yet physically started the swap yet, just collecting parts for now, which is all but completed. The car is my 1988GT, factory 5-speed.

I will be using a 94-95 ECM, which is OBD1.5, the SFI version of OBDI. It is more accurate and thus makes more power and better MPG.

I purchased a 94-95 3.4 DOHC crate motor off of Ebay for $1000. I pulled the heads, and they are in SOuthern California getting a full port/polish, and reshaping of the ports altogether. Basically redesigning the entire port shape. This job is valued at over $2000, and I should have them by Spring Break. Above them will be a set of 48g lifters (MUCH lighter than stock)

The oil pan will be pulled off and reshaped to add 1-2 quarts of oil capacity in order to not dry out the bottom end under frequent 7000+ rpm runs. I'd like to eventually run this motor reliably to 8000rpm.

The cams will be stock for now with a 13* exhaust retard. Eventually I will add lash caps for added lift and regrind the cams with a smaller base circle and wider duration.

The intake manifold will also be stock for now, just port matched. With the new cams will go a fully independent throttle body setup made by TWM Induction. This features 6 independent 48mm throttle blades, a GM TPS sensor port, relocated injector bungs with fuel rails, and 6 50mm air horns. I'll be building a custom lower intake to which these will mount and stand up vertically. The exhaust manifolds will also be stock for now, but with the cams and intake I'll be building a set of long tube, tuned equal length headers measuring 1.75" x 34" primaries with dual 2.5" collectors. I have built a set of equal length headers for a 3.4 DOHC before, and look forward to doing this.

I will be blocking off the factory water pump outlet and using a Davies-Kraig Electric Water Pump with controller. This will also act as a thermostat, and will regulate voltage according to coolant temperature. Thus I do not need the typical thermostat.

I will be deleting A/C and power steering as well. The only accessory on the motor will be the alternator, and it will have the stock 6-rib belt with a FFP UnderDrive pulley.

I have already purchased a brand new Spec Stage III clutch and Fidanza aluminum flywheel. I also have the engine mounts, I'll be using 4 Dodge truck mounts to mount the engine about 1.5" lower than it would be on factory 2.8l mounts. I will also be adding dual poly dogbone mounts, but I won't build those until the motor is on the cradle and in the car.

I still need to buy a starter, fuel lines/adapters, coolant lines, UD pulley, and a few other small things. I look forward to starting the actual swap as soon as I get home for summer break.

How about some pictures? (Ask if you want to see more, I literally have a few hundred)

The car (1988 GT 5-speed, factory gray leather, Kenwood Double Din MP3 Player, aluminum overlays, SpeedHut reverse glow red gauges w/ a 185mph speedo and 8000rpm tach, otherwise stock) and the operator:


1994-1995 Wiring Harness, complete with a Darth chip, ALDL connector, O2 sensor, IAT sensor, ECU, and a MAF sensor. Picked this up just today:





Davies-Kraig Electronic water pump with controller, picked this up on Ebay:


SPEC Stage III Clutch:



Fidanza aluminum 8lb flywheel:


Brand new alternator I picked up on Ebay for $46, and local pickup!

[product1620]

the car looks shweeeeet! :thumbleft: I'm looking forward to seeing how this swap turns out and how it performs ont the dyno. Get err done!
P.S. you have to dyno it, it's a V6 j/k

[The Dark Side of Will]

with the cams and intake I'll be building a set of long tube, tuned equal length headers measuring 1.75" x 34" primaries with dual 2.5" collectors. I have built a set of equal length headers for a 3.4 DOHC before, and look forward to doing this.

Don't forget that the increased duration of the exhaust cam regrind will require changes to your header design vs. stock cams.

I will be blocking off the factory water pump outlet and using a Davies-Kraig Electric Water Pump with controller.

The only accessory on the motor will be the alternator, and it will have the stock 6-rib belt with a FFP UnderDrive pulley.

Will an underdriven alternator be able to supply the juice to run an electric waterpump to keep your engine cool on the I-5 parking lot?

[Aaron]

the car looks shweeeeet! :thumbleft: I'm looking forward to seeing how this swap turns out and how it performs ont the dyno. Get err done!
P.S. you have to dyno it, it's a V6 j/k

Thanks! I'd like to see ver 200whp with the stock intake and exhaust manifolds, but last time I guessed a dyno number I was 20whp low, so I'm gonna shy away from that. However I love dynoes, and it will be on the dyno a week after it's running, and run at the 1/4mi by winter.

Don't forget that the increased duration of the exhaust cam regrind will require changes to your header design vs. stock cams.

The header specs are rough for right now, I'm pretty sure the diamater won't change, but the length may by an inch or two. But that isn't much to worry about yet.

Will an underdriven alternator be able to supply the juice to run an electric waterpump to keep your engine cool on the I-5 parking lot?

This is actually a concern of mine, and to be honest with you, the only reason for the FFP pulley would be the lowered rotating mass. For this reason I've elected to keep the battery out back as well. I'm still reconsidering this, it is a worry of mine, and the 6hp from the mass isn't worth the car overheating. You are right, it's just hard to have HP waiting there, but you can't touch it ya know?

[The Dark Side of Will]

6 HP?

6 * ~750 = 4500 Watts

4500 W/ 12 V = 375 Amps

That's not coming from your alternator... I didn't think the front pulley on my TDC engine was that heavy... can the UDP really be worth that much power in just rotating mass?

Have you seen dyno result for it other than the MFG's?
Dynoing in 1st or 2nd gear can make a HUGE difference in the HP gained from reducing MOI.

[Aaron]

Well FFP has a dyno showing like 10-12whp, and most people say half of the power gained is in the rotating mass. I'm not sure on this of course, it was just speculation. But as of right now, I think you're right. I forgot to consider the added stress on the water pump from the Fiero system (long), and CA driving. Not to mention the power increase.

[donk_316]

Yeah i have also seen the dynosheet for the 12whp gain with the FFP underdrive pulley.

Dyno is on a 3.1L pushrod.
http://www.fastfwdperformance.com/uddyno.html

I sent my MO away today for one.
I think with over 17 pounds of weight removed from the crank (fidanza flywheel and FFP UP) It will make a serious improvement in throttle response and "power to the wheels".... dare i say as much as 40hp. So with headers and no internal mods i bet you would see 210 at the wheels.

(threw that last little bit on for fuel for the fire)

[Aaron]

Well with just the stock manifolds, I'd like to see 200whp. Not sure if it will happen or not, but we will see soon enough I hope.

I am going to stick with the stock pulley. The 2lbs isn't worth overheating over. I'd rather have 200hp in the Kaliforna parking lot than 0. But the added power from the water pump will more than make up for the heavier pulley.

[Aaron]

So I was hoping my Dad would get us a welder before I started my swap, and he finally found one in town. I guess a local welder (profession), was upgrading and selling off his old unit.

It is a Miller 135 mig, retails for $600 new. We picked it up for $400 with some wire and a helmet (Not an auto-darkening though), and some tips, and other accessories. So not a bad deal. It has about 140 hours IIRC.

I'm pretty happy, this will make my life a lot easier, I can now do my own exhaust, motor mounts, etc. I'll have pics sometime later.

[Aaron]

UPDATE:

I decided to go ahead with the 96 intake swap and LS1 throttle body. With the heads, cam timing, and lighter lifters it'd be stupid to put the midrange intake and small throttle body on there. Plus now I can sell my current setup.

I have a 96 UIM on the way from xotikx or whatever. He is also sending me an ignition, coil packs, a bunch of random bolts, and maybe a set of 96 injectors.

I also just bought a LS1 75mm throttle body from ls1tech.com. Unlike my Z34, I am going to mount the TB right to the UIM, just make an adapter plate. This will solve the IAC passage that the LS1 throttle body doesn't incorporate, and will reduce cost (Only 1 flange needed, no piping, and no welding). Now all I need is a 96-97 lower intake, rear valve cover, and fuel rail.

[Shaun41178(2)]

so the tb will be mounted right to the plenum and not to the intake arm?

[Aaron]

so the tb will be mounted right to the plenum and not to the intake arm?

Exactly. On the W-body you need the arm because there isn't enough room, but on the Fiero you can mount it right there. I'm not sure what advantages in power and throttle repsonse this will have, but it will be easier and cheaper.

Let me dig up a pic...DreX has it done this way IIRC...

"This was the first test fit in the car. Found the the TB wasnt going to work where placed."


Hmmm. So maybe I need to rethink my plan. My adapeter would be about an inch shorter though...I'll try it with the test fit, and if it won't work, then I guess I have to build the arm.

[Aaron]

Small update, bought a brand new set of AC Delco wires off a guy at 60 Degree for $115 shipped.

I'm still looking for 96-97 intake parts and a tensioner..

[donk_316]

I also need the tensioner.

For the money, why not spend the extra 40 bucks and buy Magnecores? Ac Deldo plug wires? cmon!

[Aaron]

I also need the tensioner.

For the money, why not spend the extra 40 bucks and buy Magnecores? Ac Deldo plug wires? cmon!

I'll be making my own when I do the rest of the mods, and I'll be moving the coils towhere the PS pump used to be, or in between the Vee if I have the room. But I agree, and would've bought them, but there is no point when I'm going to move them in a year or so anyways.

[donk_316]

Do you still need coils? i have a set of "new" ones that came with my MSD interface blocks.

You should look into making a few of those adaptor plates for the TB also.

[Aaron]

Can you send me a pic of the MSD coils? They are just the GM replacements right?

As for the TB adapter. It would only be of use for those with 96-97 intakes, LS1 throttle bodies, no cruise control, etc. And I know from experience they will jack with your tune pretty badly. Plus I don't want to take any more crap, so I will build them for me, use them, and not have to worry about what others say. Like the headers..

[donk_316]

I dont have MSD coils, only the interface blocks to run the DIS-4.
I have Jegs Coils.
The only difference between stock and aftermarket DIS coils are better brass VS cruddy aluminum terminals and a supposive 5000-10000V higher discharge voltage

[willie]

I think I'd be unable to resist turboing that engine - the instant bounce to 300 + BHP would just be too hard to pass by!

[Aaron]

I think I'd be unable to resist turboing that engine - the instant bounce to 300 + BHP would just be too hard to pass by!

Oh trust me, it's hard. I think about it every day...