Crankshaft for 3.0 to 3.4l conversion
01-22-2018, 07:36 PM
#1
Crankshaft for 3.0 to 3.4l conversion
When upgrading a 3.0sc engine to a 3.4 is it necessary to upgrade the crank and rods. I’d like to save cost by not splitting the case but am wondering if longevity will be impacted with street driving and some d/e.
01-22-2018, 08:09 PM
#2
2994 95x70.4
3186 98x70.4
3164 95x74.4
3299 97x74.4
3318 100x70.4
3367 98x74.4
3506 100x74.4
3600 100x76.4
3789 100x80.4
3746 102x76.4
3942 102x80.4
3797 102.7x76.4
3996 102.7x80.4
3820 103x76.4
4019 103x80.4
01-22-2018, 08:10 PM
#3
RL Technical Advisor
Bill offered a FAR more detailed list, however this is what I usually do:
1) 98mm x 74.4mm using the larger P/C's and a Carrera/Turbo crank. I use aftermarket rods for their lighter weight and improved reliability.
2) 100mm x 70.4mm using larger P/C's and the stock SC crank. There are different piston & cylinder options here, some of which require the case spigots to be machined. I use aftermarket rods in these applications for the same reasons.
Hope this helps,
1) 98mm x 74.4mm using the larger P/C's and a Carrera/Turbo crank. I use aftermarket rods for their lighter weight and improved reliability.
2) 100mm x 70.4mm using larger P/C's and the stock SC crank. There are different piston & cylinder options here, some of which require the case spigots to be machined. I use aftermarket rods in these applications for the same reasons.
Hope this helps,
01-22-2018, 08:41 PM
#4
Steve, thx, that helps a ton. Under option 2, if I go with stock SC crank and stock rods but upgrade to 100mm piston, 46mm itbs, cams, twin plugs, headers, is around 340hp at the crank realistic?...and engine life is not materially impacted (ie crank is not the weakness)?
01-22-2018, 10:52 PM
#5
RL Technical Advisor
I would certainly use aftermarket rods and perform ALL of the oiling mods to the crank, case and center main bearing.
02-04-2018, 04:11 PM
#7
RL Technical Advisor
A 340BHP 3.0-3.4 is a race engine in personality and something that needs a close-ratio gearbox to perform properly. Further, such things are not inexpensive to build.
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02-04-2018, 06:19 PM
#8
Nordschleife Master
02-05-2018, 07:42 PM
#9
Addict
No kidding. I'd be all over that engine.
I was at Bisimoto on Friday to just hang out and watch a dyno pull. It was a 4 cylinder Honda Civic that pulled 409 HP at the wheels........Software changes found some 5 or 6 extra ponies and the owner was ecstatic. Could you imagine?
I was at Bisimoto on Friday to just hang out and watch a dyno pull. It was a 4 cylinder Honda Civic that pulled 409 HP at the wheels........Software changes found some 5 or 6 extra ponies and the owner was ecstatic. Could you imagine?
02-06-2018, 12:37 AM
#10
Rennlist Member
Bill offered a FAR more detailed list, however this is what I usually do:
1) 98mm x 74.4mm using the larger P/C's and a Carrera/Turbo crank. I use aftermarket rods for their lighter weight and improved reliability.
2) 100mm x 70.4mm using larger P/C's and the stock SC crank. There are different piston & cylinder options here, some of which require the case spigots to be machined. I use aftermarket rods in these applications for the same reasons.
Hope this helps,
1) 98mm x 74.4mm using the larger P/C's and a Carrera/Turbo crank. I use aftermarket rods for their lighter weight and improved reliability.
2) 100mm x 70.4mm using larger P/C's and the stock SC crank. There are different piston & cylinder options here, some of which require the case spigots to be machined. I use aftermarket rods in these applications for the same reasons.
Hope this helps,
Steve- With the displacement of these engine configurations being quite close I’m wondering what the character of each engine might be. I’d imagine the 70.4 crank would spin up faster but that’s just my guess. Would HP and torque be similar, and how would each behave? Thanks.
Nick
02-06-2018, 03:59 AM
#11
RL Technical Advisor
Hi Nick,
There are too many variables to offer wide generalizations, however I can tell you that all things being equal, a short stoke engine will rev quicker than a long-stroke one.
That said, long-stroke engines make more average torque than SS ones do and thats what makes street cars fun to drive.
Naturally, CR, rod ratio, reciprocating component weights, intake systems and exhaust systems all play very big roles here.
There are too many variables to offer wide generalizations, however I can tell you that all things being equal, a short stoke engine will rev quicker than a long-stroke one.
That said, long-stroke engines make more average torque than SS ones do and thats what makes street cars fun to drive.
Naturally, CR, rod ratio, reciprocating component weights, intake systems and exhaust systems all play very big roles here.
02-06-2018, 10:39 PM
#12
Rennlist Member
Thanks Steve. To me, the “character” of the engine is just as important as its power and I think it should suit the car properly. When I built my ST tribute I wanted the engine (and car) to be as close to what the factory supplied as possible. I went with a 2.5 L twin plug MFI set up and DC40 cams. The result is a very nice motor for the street with a nice flat torque curve that’s useable. Overall, I’m pleased and the engine feels correct for the brakes, suspension and 2200 lb weight of the car. Of course I also do wish I went with a larger displacement motor because more is better (or as the late Tom Petty would say because “too much just ain’t enough”), right? I’m sort of thinking a +/- 3.5L based on a 3L case might be a good idea some day.....!!
Nick
Nick
02-11-2018, 02:15 PM
#13
Burning Brakes
What cams would you recommend for a build such as this... using 9.8 - 10.1 cr w/stand alone EFI, and either Carrera intake, or 40 or 46 ITBs? Understand there are lot variables but looking for some direction..
02-11-2018, 04:39 PM
#14
RL Technical Advisor
With the OEM single-throttle intakes, the biggest cam you can use are the 964 grind ones. Beyond that, you need sufficient piston-to-valve clearance and close-ratio gears if you get aggressive.
