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Major progress today. Reinstalled stock intake manifold and throttle for initial startup and break in. We are short of some fuel related parts (lines, fittings, FPR, damper) to install the ITBs now so we wanted to save some time and prepare the rest of the car. Engine sounds healthy and vacuum is satisfactory with Toda C cams at stock timing marks (about 50kpa) so braking will not be a problem at all. Car is now heading shortly for a complete paint job, new top and fender modification for the 255/40 at 9.5" square setup.
Last edited by gzob@GearTech; 06-05-2019 at 04:14 AM.
Wow those tires looks huge, ITB's not installed anymore?
Yes, we removed them because we are short of some parts needed for fueling (line, fittings, flare fitting, FPR, damper) and we ordered them. But anyway, breaking in the engine will be better with stock intake manifold at this point. So installation after break -in and just before dyno. We might also do a back to back testing which will be of more interest for the community I guess.
Hello Guys, we are just starting a new engine for a customer who does lots of mountain driving and some autocross events. The goal was not ultimate HP like some 300+whp engines we have built in the past but max possible durability and the ability to rev at or near 9000 to retain the engine's character and S2k's special characteristic.
George, does that mean the 2.4l setups are not as reliable? Let's say one does mostly driving on high altitudes on mountain passes and still wants to keep OEM reliability..is this also possible with a 2.4l setup? Wouldn't mind lowering the rev range to around 8000-8500.
Well, it is a long discussion. But I cannot consider an engine reliable enough operating at piston speeds > 27m/sec. So for a 2.4 stroker to last, I would not push it beyond 8200 (for track use 200-300 rpm lower than that). Still, with this rev limit, you have to combat the awful r/s stroke that increases sleeve wear but on the other hand, it is a very fun to drive engine for street use. You cannot have everything in engineering obviously.
I'm doing a very similar build, not increasing the stroke. 4Piston takes 99mm stroke motors past 9000, with premium parts like the OP has here, and 106mm stroke motors for drag past 10k, but thats for drag racing. That's the same stroke as a 427ci V8.
With titanium rods and wrist pins, and a good light piston with a raised pin height, you can get a little more rod length with the stock stroke, more strength, and less weight taxing that strength. 9000 is very doable with a 90.7 stroke. The stock pieces are probably good to 8700, but for how long, I don't know.
I'm tempted to get sleeved and bored to 90mm for 2304cc, but 89mm at 2257cc is safe and sane without O-rings. Either way it's an automatic 6% power increase at 89mm, versus an automatic 7% for 90mm.
Holding the torque curve out longer for higher revs is where the power comes from. 9k is 12.5% more than 8k. 10k I think is doable, and if the torque curve holds up, 10k is 25% more than 8k.
What about the way Spoon did it with the 2.2l Kit? Using the OEM 2.2LCrank and Rods with different pistons and thinner head gasket for higher compression. OEM Reliabilty would be maintained. They claim something around 235 whp / 275 hp.
06-05-2019, 03:46 AM
