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Friday, February 26, 2010

Exhausting gasses

Finished the big tube race header and Laguna exhaust prototypes over a month ago. The Laguna is the right shape and sound but still a bit too heavy at 22lbs with two resonators. We're going to go to a thinner wall tube and lighter resonators. Should end up at around 17lbs for a header back 2.5". That's really light. The super light Fujitsubo street exhaust was our weight target at 17 lbs but its a smaller 2.375" and a shorter cat-back. The cat back 2.25" version of our exhaust might be closer to 15lbs so that's good.

Header should make lots of midrange torque, that's what it's designed for. Problem is to get the optimum runner lengths and steps in the right place, we had to wrap the primaries up like spaghetti next to the frame rail. That means it's a two piece and no fun to install. Like not even a little bit of fun. In fact, it's kind of a PITA. Sad because it's going to make lots of power but we can't expect to sell to many because of it's no compromise construction. That's what you get when you go to one of the top header builders in the country and ask for a no compromise race header. oops.

So we end up needing to design a second header that's more of a compromise. Something closer to the Racing Beat but still with the longer primaries and venturi collector the RB doesn't have. A one piece that is easier to install, and hopefully, easier to manufacture. The RB is good but I know I can do something better that will cost less. So I'm obsessive!

Been too busy to do any more than one short, inconclusive dyno test (not back to back comparison). Will try to get some dynos done in the next 4 weeks if possible.

The exhaust will be easy. We already have a customer asking for a system for an S/C car that will make 350whp. That means 2.75" and our jigs are all set up for 2.5". It occurred to me that a 2.75" race exhaust would accommodate the street turbo guys very well since they don't need quite as much baffling. So there you go, another product.

Meanwhile it's 1:21 and my second beer just ended. Good night.

Thursday, February 18, 2010

OGK Motor rebuild begins

Mike Keegan of Keegan Engineering picked up the long block today. Decided to go with the 11:0.1 Supertechs. At an actual 11:0.1, they're a tad too high compression for race gas and the unrestricted 16psi of the C30-74. So I decided to splurge on this plain motor and have the chambers polished and valves deshrouded. While Mike's at it he'll do a little bowl work and probably trim the valve guides a bit. Nothing exotic but the deshrouding will reduce the chamber volume enough to drop the C/R closer to the 10.5 or so that we're aiming for. I'd love to stick with 11.0:1 and run E85 but the fuel economy on that fuel is something like 20% worse than with normal race gas. As it's going to be and enduro motor that may end up running the Thunderhill 25, I need to maximum fuel economy. Scratch the E85 specific build. It'll still make masses of midrange torque though so its not exactly a sacrifice.

Trying to resist sticking cams in it and asking Mike to go wild with the ports. I need it finished quick so we're keeping it simple. This will also become the shop spare motor once we get the Whammy 2.0 prototype running.

The Whammy will be a no holds barred race motor. Oversquare, safe at 8500 rpm, big head flow numbers, expensive and pre-made sitting on the shelf. In 2011 that is. Gotta win some races with the prototype first :)

Other bits on the way are custom spindles and billet aluminum hubs from V8 Roadsters. These will be standard geometry. I asked the Leonards about a year and a half ago for drop spindles but they have just been too busy cranking out their LXs conversions to get them done for me. The drops are just about done now though. Excited at what the beneficial change in roll center will do for the car. A few other benifits like being in a better place in the camber curve and making room for longer shocks. Besides that, the hub and spindle assemblies will shave another 16lbs off the car. Between V8 Roadsters and 949 Racing, we have replaced the entire corner of the car except the outer tie rod end. And that is something we're also fiddling with to allow adjustments for bumpsteer.

V8R four wheel Wilwood 11.75" BBK going on too. We're going to make a one off version with "merely" 11" solid rear rotors and possibly a two piston Outlaw caliper to save weight. His current kit is engineered for a much heavier and more powerful car. The OGK is barely 2000lbs and will be just shy of 300whp in enduro tune.

While I don't think I can get everything together in time, I'm pretending that I'll have it running for the March 20 Miata Challenge event at El Toro. That will be our primary shakedown for Miatas at Mazda Raceway Laguna Seca a few weeks later. Either way, I'm so excited at the prospect of having my favorite toy awake and howling again.

Saturday, February 6, 2010

New motor for the OGK

Since late Summer '09 I had been planning and piecing together version 2 of the OGK. Real gauges, better engine management, bigger brakes, less weight and a whammy one of a kind engine with the Kraftwerks supercharger. Some of the parts are here in the shop but the stumbling point has been planning the engine. I have this theory that the block can accept a much larger bore (85.5mm) than is common practice on high boost engine. So we're going to sonic test two and cut another open to take some measurements. Then comes custom made rods, cams and pistons, all of which need to be designed from scratch. This should have all been done at the end of '09 of course. It wasn't though, so I have to "throw" something together to start aero development.

This interim motor will be basic, 100% OEM rebuild with these exceptions:

84mm 9.5:1 - off the shelf Supertech's
Forged rods - M-Tuned
Billet oil pump gears in blueprinted housing - Boundary Engineering
Valve Springs - Eibach
Crank - lightened and balanced with stock damper and 949 Racing 7.25" organic twin plate clutch
CAM- BP5A intake

That's it, no custom machining other than the crank. It won't flow more than about 205CFM or so but the C30-74 Rotrex will take care of the rest. After driving William's lap record setting 230whp 99 Miata with a stone stock 100K mile engine and the same supercharger, I realize I can get by just fine with a plain engine for now. The interim motor while it won't flow much, will have no problem spinning to 7800rpm sustained and cope with 15psi/300whp.

The impetus for the Whammy engine is twofold:
1. Increasing displacement while increasing the rod ratio from the not so favorable 1.56:1 to something more like 1.66:1. That means longer rods, stock stroke and still getting 1952cc.

2. Developing what will become 949 Racing crate motors for 2011.

With the stroker conversions already available, you get higher piston velocities and end up with nearly the stock rod ratio. There are a host of benefits from keeping the stroke shorter and increasing bore. The question remains, just how far can we go with the bore and boost before it goes pop.

With enough valve lift, our new header design and prototype manifold, we can hopefully reach something like 255-270CFM from the head. Pretty weak in the Honda world but the upper end of what people get from the BP series Mazda heads. That flow should allow it to make good power between 7000-8300 rpm which is where the rod ratio comes in. An integral part of achieving that flow will be aggressively deshrouding the valves, made easier by the bigger bore.

Such a build could be run as a genuine 8000rpm 175whp N/A (non VVT) street motor with the right intake/exhaust/ECU and also be strong enough for sustained 400whpF/I track use. The long term goal is to build an endurance racer and finish the 2010 Thunderhill 25 hour with the prototype crate motor.

Hoping to get the Whammy engine built in time to do one or two 3 hour enduros between Summer and T25. Meanwhile, we can definitely get the interim motor put together in time to run the March 20 Miata Challenge event at El Toro. Can't wait to get out there. Another goal for 2010: sub 1:50 at BW13 CW on DOT slicks.