The Pontiacolypse
 

So, it started as an attempt to find a "really bad horror movie sequel" title for the next motor, and the name sorta stuck, so I'm running with it. Basically, this is going to my take on the Pontiac 428 - what it could have been and wasn't, because of it's architecture. The basic idea is to match the bore and stroke of the 428 with an LS block by honing a LS7 out to 428, make the rotating assembly light, run higher compression (12.x:1) and do a few more things to make some very serious power, but still be reliable. And the added bonus of learning from my mistakes on the 346.

Mistake #1 - I started the build with a 140K engine. Had I left well enough alone, that engine would have easily run to 200K. I don't think that the engine was made "undependable" in the sense that it required a lot of work to keep it running (it honestly did not), I just think the new top end put so much more strain on the rings in particular that the blowby and oil consumption was inevitable

Mistake #2 - Ready Fire Aim. I build the first time up very poorly with poor parts selection, etc. I'm pretty sure this was when I cracked the block and just didn't notice it. And then ran it for three more years.

So, this time, I wanted to build a bottom end both light and strong and ready for nitrous and/or boost. not that I plan to run either (I don't) but to know that the bottom end is stout and can take what I can throw at it NA. So, enter user "Z28RPM" with a bottom end already built the way I wanted it....

https://cimg0.ibsrv.net/gimg/ls1tech...3940de950d.jpg

So, as the rest of the built, I'll be doing as follows, over the course of time:

1. Heads - The heads are going to be replaced with Mamo LS7 heads. I know, I know. But I was looking for heads that flow 400+cfm, and the others that do have massive port volumes. Mamo LS7's flow 410 with only 265cc runner, so this should give the broadest torque curve and the best throttle response.

2. ITB - I will be doing a ITB from Pantera EFI. The trick is going to be getting that to fit under the F body cowl, but I think it can be done. I can't remember what size we had agreed to on the phone, but Lance will likely remember. I want to say it was 52mm throttles. It will be cable driven.

3. Controller - I'll be doing a custom controller from Pantera also. Part of the reasoning is that the tuning on an ITB is going to be very tricky on the factory ECU anyway. Secondly, since I have the 58x reluctor, I'll need the new ECU, all the harness work, etc, so i'm into the computer already.

4. Cam - LLSR (of Course). 247/255-114+3. Hydraulic equivalent will be 242/250-114+3. This puts the IVC at 52 degrees, for a DCR of 8.5:1 at SCR 12.1:1 and the EVO at 62 degrees. The cam will only have 18 degrees overlap warm, so it actually should drive a bit better than the 346 coming out.

5. Rotating Assembly - I know the details were up in the previous post, but I thought I would note that the entire rotating assembly of the 428 is actually 0.7 lbs LIGHTER than the 346 it's replacing, including the valvetrain. I could swap springs and drop another 0.8 lbs, but I have not yet decided if I want to.

6. Exhaust - I'm keeping the current exhaust. 1-7/8 headers and dual 3". Nothing else bigger will fit.

7. Other details. I am transfering over the meziere EWP, the vacuum pump, the ATI balancer, and alternator from the 346.

When I'm done, the baseline numbers will be the 428 with the heads that came with the engine, a stock LS7 intake, the dual exhaust, and the LLSR. After that, the performance gains will simply be the heads and then the ITB's. Maybe not in that order. I still need to decide that too. But I'm not building it several times over this time, and I feel I have very clear direction at the start. "Begin with the end in mind" right?

Now, in a way, I'm putting my money where my mouth is on this. I've long thought that there is really no need to "build for torque" on a 4" stroke - and especially a larger displacement engine. It will make torque even by accident. Hell the original Pontiac 428 made 472 lbs of torque. So, the cam specs are all about high RPM power, but I'm betting it'll make great torque on stroke and displacement.

Over the weekend, I tore down the motor and did the cam and lifters. So much easier degreeing the cam OUTSIDE the vehicle! I mean NO comparison to doing it IN the vehicle.

Here is the block with the lifters out and the front cover about to come off:
https://cimg9.ibsrv.net/gimg/ls1tech...196c1cb85b.jpg

Cam Dr. Report:
https://cimg8.ibsrv.net/gimg/ls1tech...e0888fd39a.jpg

Cam:
https://cimg0.ibsrv.net/gimg/ls1tech...d697729cb5.jpg

Link-Bar Solid Roller Lifters:
https://cimg1.ibsrv.net/gimg/ls1tech...13d9c618c7.jpg

Cam and Lifters in:
https://cimg0.ibsrv.net/gimg/ls1tech...67b5aa160a.jpg

Timing set installed, and degreed. And by the way, so nice working with a cam motion cam. Installed straight up and all I had to do was verify. Did not even have to remove the oil pump:
https://cimg2.ibsrv.net/gimg/ls1tech...97a5af5fd9.jpg

Clutch transfered over without a hitch:
https://cimg3.ibsrv.net/gimg/ls1tech...1e1de213fe.jpg

EWP and Balancer installed and ready:
https://cimg7.ibsrv.net/gimg/ls1tech...898506dd1f.jpg

Anyway, that was pretty much my weekend

I'll be watching Darth! As, I'm sure, MANY others. Gonna be interesting, for sure!

Looking forward to your build and results as always.
Any concerns with the factory LS7 liners @ +.005"?

I'd be more concerned if I was boosting, but not for NA and not for a 4" stroke.

This afternoon I'm hoping to get my final pushrod numbers and get them ordered. I'd like to be able to do the valvetrain while it's easy to access.

Jaik the snaik!

Those heads on there might just be good enough... The MMS would pick up probably 20-30HP over them and the ITBs another 30-40?

But you may be at 600rwhp with a mild cam and an LS7 intake... at that point, I'd stop throwing money at it. Not for the extra $7k it will cost to get another 50-60HP.

But that's just me.

The 1-7/8 headers will probably cost you 15-20HP anyway at 7000 on a 428.

Damnit Darth... Just when I think I'm starting to catch up.... LOL.

Seriously man, that's going to be a badass motor. I can't wait to see what kind of power it makes with the ITB. If you can fit it under the cowling.. i might be suckered into getting one as well.. >>

Subbed! Can't wait to watch this one come together.

Thanks, guys!

@JF, yeah, I figure 2" headers would be worth something, but they'd still dump into a 3" dual , and I'd have to neck down from a 3.5 collector to a 3" pipe, and I am guessing / calculating that the losses are less with the slightly smaller primaries vs a choke point at the collector exit.

I'm definitely going ITB. The LS7 intake is a stop gap, and the reason I didn't spend money on more expensive intakes. What I'm really after on the ITB is it should idle and have much better partial throttle performance vs a standard plenum, as the runners won't actually see each other. it should have FAR better midrange, since I'll never outscavange the earth's atmosphere.

Over in the advanced engineering section, I seen a CAI a member custom built that looks insanely good. In the aerodynamics thread. I was gonna see about working with him to do something like that to get fresh air to the horns / funnels / velocity stacks on the intake.

SWEET......GEEZUS......:swing:

I knew you were up to something. I love the Itb setup. If you don’t mind me asking, what does that cost, with the computer? Lance is a genius at that stuff.
This is going to be fun. Hope you’ve got your heads ordered from Tony already. He’s a very busy boy these days!

Sweet build man. That's going to make some good power. I went a similar route, 427 LS3 stroker, 20K + into that thing (I think?) and counting. Honestly, I don't want to even know anymore. But when a good valve train runs up around 3K alone, it's really no surprise. Really looking forward to seeing this come along.

Was a bit disappointed with my initial numbers on the dyno though, so it's undergoing some upgrades to push it well over 500 whp. Probably a lot more than that considering it had 480 whp and 475 tq, through a 4L80e with a 3200 stall, and 12 bolt Moser. Not bad, but not my goal. Put in a cam that is almost identical to the one you have there, a .634/.634 244/252 @ .050 114+4 LSA. Should make good numbers up high. Also went up another point on compression to 12:1, and threw on an underdrive. It had the TSP stage IV before this cam so one of these days I'll take it back to the dyno to see how it does.

I'm very interested in this build as I practically just went through the same thing. If you are putting this in a f-body, you might have to modify your steering rack for pan clearance. I put in a BMR K-member, cut two groves through the mounts on the rack, and slid it over the bottom mount. Then I added spacers (tungsten steel bifilar weights from a UH-60 helicopter lol) and some 12.9 metric bolts, and a bumpsteer kit. It clears by about 1/4". In doing so I also had to fabricate a 2" steering shaft extension. I have pictures of all of it if you're interested. Otherwise, I'll just hang back and watch the build.

Awesome!!! We can compare notes for sure!!one thing, I'll always have a leg up on the dyno because T56. I already have a tubular K on it from PARacing. Ive been saying if I ever build another F car, that tubular K will be the first mod. So much room!

The motor I got is already converted to wet sump, so I just gotta swap over the F car oil pan and pick up tube. That reminds me I need to order crank scraper. The cams are pretty similar, but that's not the whole story. The LLSR is worth quite a bit of power - especially over the ls7 lifters. I am kind of a valve train Nazi. I will measure the whole thing six times over to get it perfect, because that is the stability of the engine and ability to sustain rpm repeatedly.

One thing I have been thinking a lot about is lowering the K about an inch to make room up top. So I might need to extend the steering shaft. I hadnt thought of that. I also have a bumpsteer kit and tubular spindles from burkhartchassis so I could run strange brakes up front and ditch those hubs. I kept chewing up front hubs before.

To be honest I will be pretty pissed if I end up in low 500s rwhp territory, since I was there already in the 346. If I clear 600 by a good margin, I will be happy (for now until I get used to the power again)

As to build progress I spent the afternoon measuring pushrods. Pic wont post on phone app, so Ill just say intake valves were 8.4655 to 8.4715. Pretty consistent. Exhausts were 8.4455 to 8.4500. Again, pretty consistent. So I will order 8 at 8.4670 and 8 at 8.4470 and count on variability to mix and match all the cylinders. I might end up using .001-.004 inch shims, but overall it should be really good.

If all goes well I can have the new engine mounted in the K before I leave town Thursday morning. Then my major concern will be wiring and reattaching the exhaust and transmission

Yes I was pissed. The "tuner" at the shop told me not to expect more from a setup like mine. He said it would run better on the track than the dyno, but he was also the one that changed out my injectors to 78# @ 58 psi, and left all the data stock except the flow rate. I also had a ton of KR in the scanner. Not too impressed with that shop. Some dyno tune that was.

Since then I've fixed all their mistakes, got the tune right, and now doing the other upgrades, decking the heads and swapping the cam. It should also be mentioned that it was about 110 degrees the day it put that down, on a shit tune. I still can't believe I paid for that. And I can't believe I let them change my injectors. I was being lazy I guess. I knew it needed them. Should have done it myself.

I too am a valvetrain nazi lol. I put in ferrea valves, hollow stem undercuts, 7.4" pushrods on top of comp short travel racing lifters. I can adjust my lash with the jesel shaft rockers, so it's pretty easy to set up.

One note on your stroke though... Have you checked to see if that f-body pan is going to fit with your crank? That's why I ended up changing mine out, to accommodate the 4.125" stroke.

Here's a few pics from the build, and the rack shown on the k-member.


https://cimg3.ibsrv.net/gimg/ls1tech...2ea43fb872.jpg

Checking the fit. It's still a bit on the low side, so I do have some bumpsteer problems, even with all the spacers on the end. Still drives pretty well. I don't notice it at ride height.

https://cimg4.ibsrv.net/gimg/ls1tech...97f3b3bea2.jpg

Slot to slide the rack over the bottom mount.

https://cimg5.ibsrv.net/gimg/ls1tech...8adf43ccba.jpg

Spacers and new bolts

https://cimg6.ibsrv.net/gimg/ls1tech...79dcde3b90.jpg

The steering shaft extension before I welded it all together

https://cimg7.ibsrv.net/gimg/ls1tech...8b6ef05edf.jpg

A solid piece running through the middle for piece of mind

https://cimg8.ibsrv.net/gimg/ls1tech...cd25953cf8.jpg

Almost done

https://cimg9.ibsrv.net/gimg/ls1tech...4ac1bfaa95.jpg

Jesel shaft mounts

And you should definitely get more through that T56. I want to say the typical loss on an auto is from 15-20%. I'd need an engine dyno to know for sure. But that puts this thing into the 600 range for bhp, so not terrible I suppose. I'm really hoping the change of weather and new upgrades get me to 550 whp like I wanted in the first place. I think the compression bump, tune, and cam should be worth close to that. I guess we'll see.

Here's a few in the car pics of it...
https://cimg0.ibsrv.net/gimg/ls1tech...6f4f79b49d.jpg

Meet Golddigger. She steals all my money.

https://cimg1.ibsrv.net/gimg/ls1tech...b5e331f6dd.jpg

https://cimg2.ibsrv.net/gimg/ls1tech...5b6ef61b48.jpg

I just did some more wiring cleanup... so it actually looks better now around the edges.

Hopefully I can get it all back together by the end of the week. Heads are done, and all parts should be in by Friday.

I definitely want to see how yours turns out. Keep us updated. And if you need help on how to cram that thing in there, I can be of help.

I also dropped my k-member recently as well, about 1/2" to lessen my pinion angle. Trans was pointed down almost 5*. Now it's down just 2.

Oh I see you finally let the cat out of the bag. Meow! LOL! Better said a lion out of it's cage. Roar! TQ is not needed you can't control it. Know a guy who spins the tires in 4th gear asked so how does 1st thru 3rd do he just looked at me crazy. I said from what I've seen it's useless in all gears but 5th or 6th. Told me F you in a joking way. I said I'm just saying. We got a kick out of it.

@Chopper - Your engine bay is a lot cleaner than mine. I like how you did your vacuum lines. I got mine pulling off the rear of the driver cover and that -10 line snaked all the way around. Well, I did before. Since mine is only 4" stroke, I'm pretty sure itll fit the pan. Guys put 408's in F cars all the time. Nice job on lowering the steering rack. I might rethink it and keep the 7-Qt pan.

FWIW, I have a friend who made 540 in his Z06 with bolt ons (intake, headers, EWP, ATI damper, etc) and running E85, so if I don't at least beat that with a LLSR cam, I'll be disappointed. Even though I'll be baselining with a stock lS7 intake - which are surprisingly cheap.

I don't like to throw stones at tuners in general, but to only do the flow data and not the rest is not good. On my 346, the card-style MAF was actually an obstruction. I gained MAP at WOT after removing it, so I went SD and never looked back. But yeah, I think the cam and compression will help a lot. Our cams are virtually identical, and I doubt there'd be a perceptible difference between them.. FWIW, on my 346, I went from Johnson short travel hydraulics to LLSR and still gained. I went from 496 through a stock geared ten bolt to 510 through a 4.11 geared nine inch. Then I made other changes and got more, but y'all know that story.

@Chevelle -- Lance never gave me the all-in price on it, because I am not ready to order. Gotta recover a bit. I know that the Ebay OBX are in the 1800 range, and I've seen Harrop in the 4200 range.

@Patron -- Yeay, partner! I appreciate the way you challenged me to think a bit differently for sure! I'm sorta figuring I'll be able to pick a gear to spin on the street.

Got this far last night. Bellhousing looks like ass next to the clean transmission and engine. Time to start on wiring while waiting on my pushrods...

https://cimg7.ibsrv.net/gimg/ls1tech...b1f99f54d0.jpg