Project MIDTRBO

[ALLTRBO]

It occurred to me recently that some of you may enjoy seeing my build, and I might get some good information from posting this here too.

The build thread is on Pennock's Fiero Forum, but I'll give a (semi) brief description here as well.
http://www.fiero.nl/forum/Forum3/HTML/000120.html

It's an '88 Fiero GT 5-speed with a TGP shortblock and a late Gen III top end being pushed by a Borg/Warner S258 with a .82 A/R T3 exhaust housing machined to fit, all controlled by a '730 ECU. I'm guessing it'll make somewhere around 350whp on ~12 psi, maybe a bit more.

Later on, after I get the tune and setup dialed in pretty well, I'm going to build up a stout "3200" destroker shortblock using a 3500 block and a 2.8 crank with Diamond pistons (.100 over 3400 pistons) and 5.85" forged SBC rods, and I'll probably have the top end ported and a decent matching cam installed. Along with the huge W/A IC setup that I'm building for it and serious fuel delivery and (Clutchnet) clutch upgrades, the setup should support about 600whp on high boost and race gas, with a smooth enough torque delivery that the Getrag 282 might handle it (if not, I'll upgrade to the F23 I believe it is?).

The suspension is also being worked over. It's already all rebuilt, and I'm working out the proper way to lower it without screwing up the geometry, which is an easy thing to do with the '88s (screw up the geometry, that is). There are ways... The wheel bearings will also be seriously upgraded, as will the wheel/tire combo.

I'm doing some body mods also, and will have a custom high-quality paint job.

I recently had to sell my twin-turbo IROC-Z to get a reliable daily driver, my 2010 Camaro V6 (3.6 DOHC VVT DI, 312hp) and I'm selling my 11-second AWD Talon and my stock AWD Talon, so the Fiero is going to be my only real sportscar to play with.
Because of that, I'm aiming for near ZR1 performance levels... Well, other than top-speed, reliability, ride quality and refinement. I'll save about $80,000 so that's okay with me.

Let me know what you think. If there's any questions I'll try to answer them, but most of it is covered in the build thread.

[Google Adsense]

[SappySE107]

I am not sure why you want to destroke the motor, but I cannot think of any advantage other than less power...if that's an advantage.

[Superdave]

x2, that's a quick way to lose power. Cool project though.

[ALLTRBO]

*Less torque: With equivalent components (top end/cam/etc) a smaller displacement will usually make almost as much power but at a higher rpm. The torque, however, has a higher percentage difference. Look at the stock (late) 3100 vs. 3400 hp and torque for examples. The 3400 has 10 more hp (185 vs 175) but 15-20 more lb/ft. Though the 3400 has 6.9% more displacement (3350cc/3135cc), it has only 5.7% more hp, but 7.7% more torque.
They are, of course, identical other than the bore and slightly bigger TB on the 3400. So to make an even comparison put the 3400 TB on the 3100 and it might gain ~5 hp, bringing the hp advantage of the 3400 to only ~2.8%, but not really changing the peak torque. I've seen several examples of this, stock and modified, some to a more extreme degree...
I want less off boost torque to go easier on the tranny between shifts. It isn't much of a difference, but every bit adds up. Shock loading is what kills trannies, not really horsepower. However, I still want the reasonable off-boost torque of a V6 over a blatty l4 so I wouldn't go that route (been there done that with my Talon... no thanks).

*Rod/Stroke ratio: The 3100/3400 is 1.72:1, the 3500 is 1.79:1, and the "3200" will be 1.96:1
A higher rod/stroke ratio allows more resistance to detonation, which will allow me to run a bit more boost on the same octane (possibly making up for that slight hp drop without retaining that off-boost torque). In addition, the maximum piston speeds are slower.

*Less rotating mass: There will be less shock loading on the tranny between shifts, again. It isn't a lot of a difference, but every bit adds up. It will also use up less hp to turn the crankshaft, mainly at high rpm. Not only because the crankshaft is lighter, but also because the rod journals and the lighter counterweights take away weight from the outside diameter of the rotation, where it counts most.

*Rod availability: Using the 76mm crank and the 3400 pistons (.100 over) will allow me to use 5.85" SBC rods (slightly machined of course) for the perfect piston height vs. quench clearance vs. head gasket thickness, and very stout 5.85" SBC rods are somewhat easy to find, hence easier and cheaper than custom options that will handle ~650 hp.

*Crank strength: This one probably doesn't differ as compared to the forged 3500 crank, but comparing to the 3400 steel crank, there is more overlap between rod journals with the 2.8 crank. Many say that it doesn't matter because no one has ever broken a 3400 crank, but I don't think anyone has ever pushed ~650hp through one either (correct me if I'm wrong).

*RPM capability: All of the above adds up to a rotating assembly that'll probably beg for 7500 rpm with a few valvetrain mods and mild turbo cam upgrade, and intake and head porting (I'm talking about you, Ben. ). Maybe even 8000rpm. My heart skips a few beats at the thought of a jet-like spooling and screaming 7500-8000 rpm 60V6. The 282 doesn't care to shift above 7k from what I hear, but I think that's covered by an aluminum flywheel and lighter rotating assembly, along with my friend Will (aka: "The Dark Side of Will" on RFT and "Will" on PFF) with his awesomz 282 rebuild skillz, heh.

I could also add some panzy-arse reason like the extra gas mileage it could theoretically get, but this car isn't being built for economy, though it'll still be good enough.

I think that about covers it.

[86FieroSEv6]

Awesome build, man.


Now where's that damned Jealous button . . . ?

[ALLTRBO]

Thanks. Don't be jealous, it's still ugly and it doesn't even run yet! (Getting close though)

Here are a couple pics that some may appreciate. They're in the PFF thread, but if you don't want to read it you can at least try to figure out what happened here... (look harder. )





And here are couple pics of the goodies...





(The turbo is just resting on the flange)

[timg]

That's a great looking project and a nice choice of turbo. I'm looking forward to seeing how it performs. Thanks for the post! Please keep us updated.

Tim

[RedZMonte]

looked threw the PFF site, Loads more cool pics of the build. Looks good, excited to see the final results. there are a few guys with modified TGP setups making some great power. Cool project.

S

[ALLTRBO]

Thanks guys. I'll definitely keep up with the PFF thread, and I'll chime in here from time to time to summarize the progress.

[Dave96z34]

You de stroke an engine so you can run more boost safe.