Anyone figured out how to make it bullet-proof?

GT40racer · 11-26-2008, 09:39 PM

I was planning on doing a turbo install on my 97 dohc (87 rebodied Fiero) and am thinking about ways to beef up the engine before putting the squeeze on it.
I've already got the ARP rod end bolts and main cap bolts but would also like to replace the head bolts with ARP studs.
Other items on the wish list would be lower compression forged pistons, stronger rods, forged steel crank, four bolt end caps, girdle etc.
I've seen posts about trying different forged cranks and 3100 main caps but has anyone actually done it?
Is there a proven list of parts that interchange from other engines that results in a stronger bottom end?
I may have to pull my engine to repair a bad head gasket so it would be a perfect time for a highperf rebuild.

timg · 11-26-2008, 10:24 PM

I'm going with low compression forged pistons, forged rods, plus ARP studs. I'm not sure how much more can be easily done. Pauter made the rods and CP made the pistons. They should have these in their database now.

Tim

GT40racer · 11-26-2008, 10:56 PM

That's a great start! Hate to ask but what do would the set of pistons and rods go for? Since they're in the catolog now hopefully cheaper than a custom job.
What compression are you planning on getting? Are the pistons for an overbore? What is the part number for the head studs? I was thinking that the L67 forged crank would be a possibility too. That only thing left would be the caps. The dohc two bolt caps would be the weak link I imagine. They don't look too strong.
It would be great to get everything together in one package for the ultimate proven rebuild kit.

Joseph Upson · 11-27-2008, 01:05 PM

Quote:

Originally Posted by GT40racer

That's a great start! Hate to ask but what do would the set of pistons and rods go for? Since they're in the catolog now hopefully cheaper than a custom job.
What compression are you planning on getting? Are the pistons for an overbore? What is the part number for the head studs? I was thinking that the L67 forged crank would be a possibility too. That only thing left would be the caps. The dohc two bolt caps would be the weak link I imagine. They don't look too strong.
It would be great to get everything together in one package for the ultimate proven rebuild kit.

The L67 is the 3800 so that crank is not an option. I don't recall who, but there is a Fiero member on Pennocks with a 400 hp turbocharged 3.4L DOHC Fiero and I do believe the engine is stock but well tuned.

I don't believe adapting the 3xxx engines aluminum oil pan, windage tray and main caps would be very difficult aside from the align boring that would be needed afterwards as long as the bolt hole locations are the same. That should add quite a bit of integrity to the bottom end above stock. If you opt for high performance small block chevy rods which have been narrowed for use in the V6, and a piston change, try to make sure the end result is lighter than the items you are replacing, a balanced lighter assembly will buy you a lot more dependability at high revs over the long run as well as make more power.

The piston and rod combination I'm planning for my fully forged engine build so far has reduced reciprocating weight by nearly 100 grams per piston and rod assembly. It's not a 3.4L but the principle is still the same, less weight = less stress.

Driver_10 · 11-27-2008, 08:22 PM

Hey Joseph. Did you ever check back with that guy about the "press-on" crank trigger wheel?

GT40racer · 11-29-2008, 02:02 PM

Has anyone used the newer 3500 forged crank? I've read that aftermarket sbc forged rods maybe used as well.
I guess maybe a better question would be if anyone has made enough power to actually break the bottom end?

ForcedFirebird · 11-30-2008, 12:39 AM

3500 crank is a great and inexpensive option. I'm not greatly familiar with the 3.4DOHC DIS trigger (unless it's the same as the other 60*'s), but as Driver_10 mentioned, the DIS wheel needs to be replaced with a 7x reluctor. The 3500 crank shares the main bore diameter with the rest of us, but has a larger 2.249" rod pin. John (Driver_10) is the first that I know of that is going to try a 3500 crank in an earlier engine.

gpchris · 12-01-2008, 12:45 AM

I dont think a crank is worth it.. I dont see the thing breaking.. I say get the SP aftermarket pistons with SB chevy rods (maybe a little bit shorter to lower compression). and youve got a solid bottom end that doesnt break the bank.

timg · 12-01-2008, 06:50 AM

The pistons were $1050 and the rods were $1,176. They were one offs which included measuring some pistons and rods I sent in, so another run might be cheaper. The pistons were 20 thousandths over and had a compression ratio between 8.5:1 and 8.75:1.

Pauter forged rod part number: CHV-230-539-1448F

The CP pistons weighted 431 grams each. Sorry that I don't know the part number.

Tim

ForcedFirebird · 12-01-2008, 08:07 AM

Quote:

Originally Posted by gpchris

I dont think a crank is worth it.. I dont see the thing breaking.. I say get the SP aftermarket pistons with SB chevy rods (maybe a little bit shorter to lower compression). and youve got a solid bottom end that doesnt break the bank.

Shorter rods to lower compression is the wrong way to go about it. Increasing the quench will actually cause more detonation.