jimlab

Nope, don't have a web site... unless you count my thread in the 3rd gen. section.

Here's a good shot of the intake on the engine...

89S13

SWEEEET!!

rotarygod

iTrader: (1)

Damn those are short intake runners. How high do you rev that engine? It should flow very well! Is that throttlebody just one big oval plate. It doesn't look like the dual rounds. Very nice.

jimlab

Very short runners (see picture below), but it's a stroker engine (396 CID) so it still makes a lot of low end power too. In fact, it makes 400+ lb-ft. of torque from 2k-8k rpm and about 350 lb-ft. at idle.

Arbitrary redline is 8k rpm, but I'll probably be shifting at 7,500-7,600 where horsepower starts to drop off. The throttle body is an Arizona Speed & Marine 1,300 cfm monoblade.

banzaitoyota

Is that a weld inclusion on that first runner???

KiyoKix

WOW, those runners are stoopid short! I wonder what it's like to pilot a beast like that. Very nice setup man, what's your compression ratio on that motor? How long did it take you to build, and how much *now bracing myself* did you put into it?

Once again...hell it ain't a rotary, but DAMN if it isn't a nice piece of work! My hats off...

jimlab

Sort of looks that way, doesn't it. Not sure, I didn't take those pictures. However, I do know that the insides of the runners are totally smooth, and Hogan's would not have delivered it with any leaks, since the intake was fully flow tested before it left their shop.

jimlab

I've been wondering the same thing for quite awhile now. 11.8:1, about a year and a half, give or take, and about $34,000. Let me explain...

Many of the components of the engine had to be custom made. For example, the billet crankshaft alone was just over $3,000, but it weighs 18-19 lbs. less than a stock crankshaft, and about 23-24 lbs. less than a typical forged crankshaft of the same size. My billet steel connecting rods were $2,150, but they only weigh 505 grams. Titanium rods weigh 490-495 grams and aren't practical for street use, and typical forged 4340 H-beam 6.0" rods weigh around 675 grams, so you can see the advantage there, too. That's a savings of about 48 oz. (for the set of 8), or just about 3 lbs. Not only do those two components shave about 26 lbs. from the curb weight of the car, but they also shave 26 lbs. from the weight of the rotating assembly. This engine revs like no 396 cubic inch V8 has a right to, in other words.

The heads had to be custom cast. The raw castings were $1,995. Then came $1,500 in porting and flow testing. $400 in valve springs, $1,500 in Titanium valves (also made to order), another $300 for a custom valve job, and $1,100 for my Crower shaft rockers. The heads were then sent to Hogan's, who built the intake to match for $2,875... You get the idea.

It costs a lot to make this much power naturally aspirated in a relatively small package, on pump gas, and retain streetability, but I took a page from Toyota's 2JZ-GTE book and overbuilt the engine in many ways. I'd be the first to admit that I went more than a little overboard, but I wanted the best, lightest, and strongest parts possible, so that's what I got. I built the engine to take the abuse of 1,000+ horsepower on forced induction or nitrous and I'm only asking it to make ~650-660 horsepower naturally aspirated. The result is the most reliable 650-660 horsepower money can buy in a package significantly lighter (and more compact) than a 20B.

89S13

Jimlab
My props to you for doing it right, it's an awesome engine.
One question though, $1995 sounds a bit cheap for a custom raw casting. Did you just tweak an existing casting?

RX-Heven

iTrader: (1)

That also comes in at more than 2.5 times the cost a full tilt 20b that also can reliably put down the same power (with the same untapped potential). Hard for me to imagine all those parts moving around being more reliable than any (properly tuned ) rotary. I won't argue the weight because I'm sure it is lighter, but I would like to know what it weighs. Also, are you sure that engine is smaller than a 20b? I never found out for sure, but I thought small blocks were shorter but had more 'girth' to them than 20b's.
BTW, that is an awsome engine...

jimlab

Yes. All Air Flow Research had to do was revise the cooling passages to adapt the head to use on an LT1. The intake and exhaust passages remained the same as the SBC original.

jimlab

I actually went so far as buying a 20B core before deciding to go with a V8. It weighed 561 lbs. on its crate, with intake and stock turbo/exhaust manifolds. My LT1 crate engine I used for test fitting was just over 475 lbs. with a few extra parts thrown in, no exhaust manifolds. My 396 will be about 40 lbs. lighter than a standard LT1, and about 20-25 lbs. heavier than an LS1. I asked to have the engine weighed before it's shipped, but I'm considering buying a 4-corner scale setup which could easily be used to weigh it once it arrives.

I think your estimate on the cost of a completed 20B conversion is a bit low, but it's not important. I didn't build my engine to compete with a 20B conversion as far as cost is concerned. It should be pretty obvious that I don't care that much about cost.

RX-Heven

iTrader: (1)

No it's not important really, at least to some of us. But I like to nit-pick I spent 14k on my 20b build and held back on nothing except going with a custom e-shaft which is not necassary for my application. Oops, make that two things, I didn't go pp with it either. That is minus the turbo and intake/exhaust manifolds. I even have a dry sump system for it. Just not as many internal parts to spend bucks on.

Hmmm, that v8 is still na though....

Do you still have that 20b? If so,is it for sale?

jimlab

Sorry, sold it quite awhile ago.

Evil Aviator

Your engine is nice, but it is not a "full tilt" 20B. Had you built your 20B to full GT race specs with the competition water pump, PP, aluminum housings, lightweight locked rotors, hardened gears, competition throttle body intake, full balancing and blueprinting, etc., it would have cost you over $30K and would still be 100-150 peak hp short of Jimlab's V-8.