Money is no object, 3.75L I6

I agree, would have been nice! Maybe run them in Baby Grand National NASCAR too. Baby Grand was 5.0L and under. Junior Johnson ran a 68/69 Javelin in Baby Grand with a 290. At least I think it was JJ... not sure if it was 68 and 69 or just one of those years. But a six cylinder class would have been nice. Well, there were six classes for the dirt tracks and amateur/hobby asphalt tracks.

amc67rogue wrote: Tomj ; Does that motor have a stock 199 crank or a billet ? If is't a stock 199 how many counter weights does it have ?

Eight!

http://www.wps.com/AMC/Navarro-turbo-motor/images/crank1.jpg
http://www.wps.com/AMC/Navarro-turbo-motor/images/crank2.jpg

I talked to Navarro's engineer in person, he said AMC gave them all the parts they wanted, and that all the cranks were factory parts. As far as he recalls, there was never a steel billet crank, only cast factory parts. I've written this before, but the rumors persist without any evidence and in the face of first-hand (OK, second, from me) information.

Slate wrote:  An engine with walls that thick is screaming to go turbo.

It *was* a turbo motor... Navarro made two versions (at least), a "550 hp" single turbo, and a "750 hp" twin turbo. Mine is, as far as I know, one of the test mules of the single turbo. This particular motor was run at Buttonwillow, a road race track, with the Indy dry sump and it went dry in a turn and scored the crank. The guy said he'd never seen Barney so mad for makign such a dumb mistake. The scoring is minimal, and my pile came with a set of .010" under bearings so it seems clear the intent was to rebuild it, but who knows of course, it was a long time ago.

Recall this was the late 60's, so turboing was not common I think. The twin turbo motor had Hilborn mechanical fuel injection (I have some of those parts) but at least an early single-turbo motor had a huge Delorto carb.

Mine's got stock main bearing setup; another ex-Navarro employee I talked to, still alive, Marino, said the twin-turbo block had been converted to four-bolt mains.

Neither motor had an intercooler. The 750 hp motor was run at 45psi boost! So air temp must have been insane. Hence the overkill cyl walls, I assume. Intercooling should have been there but no pictures I've seen shows it.

Car #50 never qualified, so all this stuff fell into obscurity.

But it does tell about the capabilities of the AMC six. With an intercooler and EFI 500 hp ought to be easy enough.

farna wrote: The head is the biggest issue, if you want a crossflow head. If you're redesigning the head, go with an OHC design -- no point not to. Before reinventing the wheel, check other six cylinder heads though. Find one with the came bore centers and there's a good possibility it can be modified to bolt to the AMC block. Me, I think the last couple 4.0L heads are really good, good enough that the effort and expense for a new head is questionable. Ron Waters said he turned a 258 to 6000-6500 rpm all the time, and that was without the benefit of even a 4.0L head (all of which are substantially better than the 258 and older heads). There is a roller cam available, but durability is questionable. The cam is ground from a standard cam blank and then surface hardened. No one knows how long it will take to wear through the hardening -- I think the company suggests somewhere around 25K miles? If you're spending money get a hard billet roller cam and work with the 96 or so head. SOME 4.0L blocks can be bored out to 4". Beware of core shift -- have it sonic checked first! Sometime around 92-93 Chrysler took a bit of metal out of the block, so get an early one. I'd go ahead and look for a 87-90 Renix EFI block just to be sure.

Here's your OHC motor (Pontiac, but it's still a retrofitted pushrod motor)

http://i86.photobucket.com/albums/k102/willthethrill256/t3.jpg

Edited by carnuck - Apr/12/2012 at 2:01pm

Tomj ; Does that motor have a stock 199 crank or a billet ? If is't a stock 199 how many counter weights does it have ?  

If money were no object, why stop at 3.75L?