Since I committed to the DOB R-Spec, I've been looking for ways to improve on my current motor. A lot of specifics are up in the air as this project is a ways off, but I'm trying to do some research and ask questions now so I can start to form an idea of the final goal and cost.
Concern #1 is going to be strength. Without filling the block, this is gonna be tough. My goal is to max out the 3.4L Whipple on e85 with a higher compression ratio. Best guess is 1200-1400hp. Why? Top speed and mile drag race. For road race I'm going to be running a much lower boost setting. I want to stick with an aluminum block for weight savings on the road race track, and I also don't like how the iron Boss setups have fewer main bolts. I feel like with enough tricks and $$$ it should be doable. I'm also looking into putting larger head studs in and O-ringing the block to keep the heads on.
Concern #2 is performance. Coatings, displacement, etc. Basically maximizing the amount of power I can get through changes in the motor.
I'm for sure doing a dry sump system with a billet oil pan, a DSS mains brace, a full front thust bearing with a billet plate where the oil pump used to go, and a rear main seal billet plate. Also thinking about cryo treatment and WPC treatment for everything. I'm also modding the cooling system so both banks run at the same temp.
I'm looking into wet sleeving the block with Darton MID sleeves, which opens up some unique possibilities. The MID sleeves apparently increase the overall strength of the block, while also increasing bore and cooling capacity. Their bore specs are 92-95mm. Of course, these are Dartons claims and I'm still looking into them. For the time being, I'm assuming they're correct and looking at my further options.
So with that I can easily run a larger bore and unshroud the valves. Not sure on the exact bore needed to accomplish that, but I would like to run at least that large. If Darton comes back and tells me I can max out the 95mm bore, then I may go that route.
The other question I have is stroke. I would love to do a 3.800" stroker, but I have some concerns about the integrity of that. I've been reading some engine books lately, and some people have concerns about the strokers. Chief among them is the stability of the piston in the bore at higher RPMs since with a stroker it comes further out of the bore at the bottom. Again, I would love to have more displacement, but not at the expense of integrity. Any experience here?
Minimum displacement with stock stroke length and the MID sleeves at 92 mm comes out to 292 cubic inches, a fair improvement. 95mm with stock stroke is 311 cubes. To me anything 5.0 or bigger is a big step up, especially if the sleeves improve cooling and strength while they're at it.
Maximum displacement with the 95mm bore and a 3.8 stroke is 334 cubes. Idk if that's been done on an aluminum block. Could be sketchy.
What're everyone's thoughts? Obviously there are big performance gains from unshrouding the valves, but once you're there is there really anything to be had from further boring and stroking?
