LS4 / 4T65-E spy pics

[Sinister Fiero]

More pics are up of the engine disassembled and the heads awaiting a port job (which I am working on now). The port casting from the factory on these heads is some of the best I have seen from GM in quite a while (although I will admit I haven't seen the new L92 "super" heads yet). Despite this tho, they do need some help especially around the valve guides which is where I will concentrate my efforts. Then it's off to the machine shop for a multi-angle valve job.

I am going to see about getting this engine weighed so I can post up some numbers on that.

-ryan

[Sinister Fiero]

Got some more info for you tech-savvy people. The LS4 heads bolt to the block using 15 bolts each. Before you get too excited, only 10 of these bolts actually have anything to do with cylinder sealing. The other 5 (8mm x 1.25) just make sure the head is securely clampted to the block near the lifter valley. The 10 large bolts are metric 11mm x 2.0 thread pitch -- not all that common. Looks like I am going to have to special order a thread chaser just for this project.

The stock cast iron exhaust manifolds have a 1.75" ID for the primary tubes -- believe it or not. Although the outlet for the front manifold only measures about 2.0 inches. There is some room in the casting to open this up a little but I am not going to go too crazy on it because I don't want to weaken it. The rear cast iron manifold has the same size primary tube ID and has a 2.0" ID inlet for the crossover pipe. The outlet uses the same size flange as a 3800 Series 2 (3 inch).

[The Dark Side of Will]

Northstars are 11mm x 1.5.
Dam GM and their 11 mm bolts.
Lots of engines with 4 head bolts per cylinder hold a lot of cylinder pressure.
The valley is one of the major structural areas for a V engine, as far as block rigidity goes. Modern GM engines have been a LOT beefier in the valley area than older ones.

[p8ntman442]

The 11x1.5 has been gm standard for a long time. Its good from an engineering standpoint because you can have techs putting engines back together without worrying they lost a bolt and grabbing a grade 8 from a bin. It sucks if your doing a custom application and need them though. From my experiance you can timesert the holes to 7/16" bolts. Which should be amply sufficient if your not running mega boost.

11x2.0 is odd. Does anyone have a formula for calculating clamping force? Can you see how much you gain by going to 2.0 over 1.5 with say 5 mm of thread depth.

Ryan, how much thread engagement is there on the bolts? Less than on a N*?

[txf]

Shouldn't this be in advanced?

Great observation on the flexplate.

[Sinister Fiero]

Ryan, how much thread engagement is there on the bolts? Less than on a N*?

Thread depth on the bolts is about 0.040" as best as I could measure.

[txf]

still have that flexplate accessible? If so could you get me the measurements off of it?

Crank hole pattern center to center of oposing holes
Total diameter
distance from one TC hole to the next.

[Sinister Fiero]

still have that flexplate accessible? If so could you get me the measurements off of it?

Crank hole pattern center to center of oposing holes
Total diameter
distance from one TC hole to the next.

Crank hole pattern from center to center of opposing holes is approx 3 1/8" as best I could measure. Center hub diameter is about 2.085" or so.

Overall flexplate diameter measured at the starter ring gear is about 12". Torque converter bolt holes measure about 4 7/8" from the center of the hub out; and about 8 1/2" from center of one TC bolt hole to another TC bolt hole.

The torque converter bolt holes and overall flexplate diameter are THE SAME as a 3800 Series 2 SC flexplate. The torque coverter used on this transmission appears to be the exact same as those that are used on the 4T65-E HD's that come with the L67's -- 258mm dia.

[txf]

My measurements are 3" CTC crank holes and the rest match yours. You state that it's 3 1/8 to the best you can measure. Measuring from outer edge to inner edge is the same as CTC. But I think we found a $57 replacement to a $200 Street Dreams part. Just saved me some money. Not to see if I can make my own adapter plate to put the block and trans together!!! Thanks Sinister!!!

[Sinister Fiero]

Finally got around to weighing this pig. Total weight for the engine, all assy's minus p/s pump, minus wiring harness is 478 lbs.

Contrast that with just the longblock (no assy's, no intake, no water pump housing/front cover, no brackets or mounts, etc): 339 lbs.

So next time somebody gets all excited about how light an all-aluminum V8 is you can raise the BS flag because they are probably not taking into account all the assy's, other parts and hardware that go with it once installed in the car.

Just for reference I have seen weight figures on the 3800 SC around 450 lbs; but I don't know what all assy's that includes. I guess I could call up Ed Morad and ask him how much shipping weight is on just an engine minus transmission.

[The Dark Side of Will]

478#'s? That seems like a lot over the 339 longblock weight... I would have guessed 60# worth of accessories, but not 140. That's impressive.

The FWD waterpump housing, however, would appear to be a LOT heavier than the RWD w/p housing.

Don't forget that even at 478#, it's still 70# lighter than the similar number for an all iron Chevy: 550#.

[p8ntman442]

on a v8 block you should deffinatly be able to shave 100 lbs going from iron block/heads to aluminum block/heads.

[Sinister Fiero]

478#'s? That seems like a lot over the 339 longblock weight... I would have guessed 60# worth of accessories, but not 140. That's impressive.

The FWD waterpump housing, however, would appear to be a LOT heavier than the RWD w/p housing.

Don't forget that even at 478#, it's still 70# lighter than the similar number for an all iron Chevy: 550#.

The front cover / water pump housing only weighs 15 lbs. The problem is even though all of the bracketry used on this engine is aluminum (with exception of the alt bracket which I did NOT take into account in these figures); you need to remember the fasteners weigh something too. Hell, the starter, alternator, and related mounting hardware weighs 24lbs! The plastic intake w/ throttle body and hardware weighs 15lbs! This stuff adds up.

That's why I laugh when people try to tell me how light a SBC can be in a Fiero, quoting the weight of just the engine. Well what about the adapter plate? What about the mounts and the mount brackets? All of that stuff has to weigh something.

Then you have the people who can't seem to find car scales but rather they take their cars to semi truck scales made for 80,000 lb loads. You can't honestly expect me to believe those scales are going to be 100% accurate when you park a car on them that weighs less than 3,000 lbs. That's why I don't pay too much attention to people throwing out vehicle weight figures they got from a semi truck scale. If you want accurate numbers, take your car to a performance shop and have them weigh it on a 4-corner scale system or equiv; something designed for the weight of a car; not a 80,000 lb truck.

[Sinister Fiero]

My measurements are 3" CTC crank holes and the rest match yours. You state that it's 3 1/8 to the best you can measure. Measuring from outer edge to inner edge is the same as CTC.

Remeasured today using a dial caliper and sure enough the distance is 3.125". Also, this flexplate has NO counter-balance weight.

[The Dark Side of Will]

478#'s? That seems like a lot over the 339 longblock weight... I would have guessed 60# worth of accessories, but not 140. That's impressive.

The FWD waterpump housing, however, would appear to be a LOT heavier than the RWD w/p housing.

Don't forget that even at 478#, it's still 70# lighter than the similar number for an all iron Chevy: 550#.

The front cover / water pump housing only weighs 15 lbs. The problem is even though all of the bracketry used on this engine is aluminum (with exception of the alt bracket which I did NOT take into account in these figures); you need to remember the fasteners weigh something too. Hell, the starter, alternator, and related mounting hardware weighs 24lbs! The plastic intake w/ throttle body and hardware weighs 15lbs! This stuff adds up.

That's why I laugh when people try to tell me how light a SBC can be in a Fiero, quoting the weight of just the engine. Well what about the adapter plate? What about the mounts and the mount brackets? All of that stuff has to weigh something.

That seems REALLY heavy for the plastic intake. I haven't weighed it, but the Northstar's feels like it weighs 5-10, but certainly not 15. How heavy is the drive-by-wire TB?
24# is beastly for a starter. Again the Northstar unit weighs about half that.

I think that an aluminum block on a SBC is supposed to save 80-100# and aluminum heads 50#.

[Sinister Fiero]

That seems REALLY heavy for the plastic intake. I haven't weighed it, but the Northstar's feels like it weighs 5-10, but certainly not 15. How heavy is the drive-by-wire TB?
24# is beastly for a starter. Again the Northstar unit weighs about half that.

I think that an aluminum block on a SBC is supposed to save 80-100# and aluminum heads 50#.

The starter AND alternator with related mounting hardware both weigh 24lbs.

I will see about weighing that fly-by-wire TB later; but I don't think it is more than a couple of lbs.