Jeff20B

iTrader: (13)

If a modern Nikki can run on a reverse runner manifold with fully separate runners, it can work. I got a channeled old school Nikki to work on this half BP.

The ports are only 74 spec. That means later closing only. The openings are still stock, but with just a smoothing of the 90° edge, which I also did on the half BP. Think about it.

Jeff20B

iTrader: (13)

Yeah, I have two of these reverse runner manifolds. One for Percent's REPU and one for my MG. His is getting a boost prepped Nikki so we were thinking it'd need to be channeled, but not if it's getting a half BP (not sure if it's wise to channel a reverse runner). It was already ported to 74 spec, which is correct for a 74 REPU, and it's getting a turbo so the smallish Nikki, only having 20mm primary venturis, is not a problem. The turbo will force extra in there to make up for the small primaries. Otherwise I'd say go with a Sterling for its 22mm venturis, or an old school Hitachi which also have 22mm primary venturis. The 76 Hitachi that's going in the MG already has 22mm venturis.

So either way a broad power band is good and will suit both vehicles.

Jeff20B

iTrader: (13)

On second thought, explain why a boosted engine needs bridgeports. I may have asked this before, but it seems to me that you use stock ports with boost, and large ports if NA. You can delay closing timing slightly with boost, as the high pressure can fill the cylinder (chamber) longer than if it were stock ported and/or NA, but otherwise it's fine to leave the ports stock and just crank up the boost. I've heard of 400HP on stock ports from an FD engine. I'm sure others have heard of more. FD secondaries open and close at 74 spec. Primaries are a little smaller of course. So for the REPU engine, all four ports are 74 spec; that's more port area than an FD! Exhaust ports (after some porting) are now as large as FD. I guess we could go bigger (to match the larger intake port area) but it's a truck so leave them at FD/T2 spec.

Believe me you will not find it very nice to tow something with a bucking engine under decel. Ever break a Reese Trailer hitch? Niether have I. I bet it's not pretty.

j9fd3s

iTrader: (3)

same reason it needs it NA, more power. although as you point out the power level is enough higher that it almost doesn't make sense.

examples? sure erniet, made 500+ on a stock engine, 700+ on a bridgeport, and is over 800 on a semi PP engine. i don't know about you but 500+ is already too much in a street/roadrace car....

shoot maxt makes like 440rwhp with the boost controller off and something like 10psi...

PercentSevenC

j9fd3s is right. There's no fundamental difference between an NA engine and a boosted one as far as intake tuning goes (well, once the air gets to the plenum, anyway). The idea would be to make the same power at lower boost (and thus leaner AFRs, and more ignition timing for off-boost performance, etc.). Plus, it'd just be cool. I guess I'd have to see how bad the bucking is with a heavier flywheel.

Jeff20B

iTrader: (13)

I would agree 500+ is too much in a 1st gen or REPU, and Percent agrees with me. Untractable is the word that comes to mind. But I know he has a half bridge in him that needs to come out, and I'd like to help him with that lol. I just don't think the truck is where it should go. So that just leaves the 1st gen.

Hmm, I already said I was not interested in doing a half BP on a set of FD plates, but if it's true that there is no communication between primary runners and secondary runners, I may just change my mind. I'll have to take a good look at the FD TB and UIM (and I'll dig out the Y pipe too! Sorry, I've been so busy).

Another option is to go with an S4 NA in the REPU, as was the original intention before this 4 port came along. It wouldn't get half BPs because there is already a ton of port area in the end plates (I'm in agreement with rotarygod that you don't bridge 6 ports). And it can get broken in with a Nikki setup until he's ready to go EFI with a MegaSquirt. Also already have the header kit and two long glasspacks to make a 51" long primary exhaust similar to what's planned to go in my REPU. Simple, reliable, good amounts of low end torque at low RPM on the small ports, and then good flow (I guess?) at high RPM for good power. Compare this to a set of 74 spec ports on a 4 port engine, which have less low end torque than 12A size ports. Like j9fd3s said, the 4 port is a compromise port; sized in the middle between too large for low end and too small for high end. Kind of a happy medium, sorta. We've got two rotating assemblies here, an S3 and S4, also have a flywheel for each, so whichever. I say go with the S4 for the slightly lighter flywheel = more acceleration and higher compression ratio. I'll also swap in my S4 turbo oil pump and a set of S3 tension bolts so we don't have to use the dinky S4 bolts.

peejay

Bridge ports have more exhaust energy at the same power level so they do a really good job of spooling a turbo... and they make more low and mid range torque too.

zaridar

iTrader: (3)

looking good! im going to have to do the freeze plug mod myself!

Jeff20B

iTrader: (13)

Yeah, Percent mentioned that. It's starting to sound like a good idea. Maybe going with a light steel flywyeel would be a good idea instead of aluminum, eh? Then again, this half BP 12A seemed to do fine. I'll put it through another heat cycle before lunch and see if it's any easier to start.

Here's an idea for the trucks. I'll do the S4 NA in the white truck and the half BP in the red truck (MG's engine). Both with stock flywheels. If the half BP works out, we can do one in the white truck later. Sound good?

Jeff20B

iTrader: (13)

You have to fill the ACV port. Or you'll get a hot manifold. Pick one.

Jeff20B

iTrader: (13)

I forgot to ask what intake manifold you have. It looks like a wrap around DCOE. Those and other aftermarket manifolds don't really need the ACV port filled when you add freeze plugs, but it does prevent exhaust contact on the manifold directly. Does it really matter? Maybe only a little.

LizardFC

iTrader: (1)

Something to consider when plugging up those coolant passages - they're there for increased efficiency/performance as well. They create a hot spot on the manifold which helps vaporize fuel film that builds up on the runner surface. Whether or not the decrease in intake temps overcomes the decrease in vaporization, I don't know All I can rely on is the R&D that companies like Racing Beat have put into their products and hope that they've done their homework. I don't have an aftermarket manifold to look at... do they have coolant passages?

PercentSevenC

LizardFC: I've never seen an aftermarket manifold that has them.

Jeff, that sounds like a plan to me. And no big deal about the Y-pipe, it's not like I can do anything about it yet anyway. Whenever you have time is fine.

LizardFC

iTrader: (1)

Thanks. Then its probably safe to assume that the benefits of cooler air outweigh the reduced vaporization. To me, it's worth plugging the things just to keep them from springing leaks all the time.

Jeff20B

iTrader: (13)

All right I took some videos but I can't upload them. PercentSevenC will later.

It fires up really fast now. It takes about 3 or 4 seconds.

It drives pretty well. No more worries about an aluminum flywheel. I'd say it's ready but I'd like to give it two more heat cycles.

The idle has a very slight brap right around 1k. It comes and goes. I think this is normal behavior. It's got a pretty strong idle otherwise, with plenty of low end to pull daily driver duties. As I understand it, full bridgeports are super weak right off idle and p-ports are actually a little stronger down there, as in you can draw the idle down with the clutch as you start to launch, but full bridgeports hate that. Well this half BP doesn't complain. I played around with the idle screws and got it to drop down around the bottom of the tach and it didn't stall, but it didn't really like it. That's like nearly cranking speed. I was kinda impressed.

I'll post some pics of the engine bay this evening.

Jeff20B

iTrader: (13)

engine running


old school carb


compost bin thermometer showing oil temp in pan


close up


This is where it likes to idle

gauges on the left don't work most of the time. I'll swap in a mechanical guage tomorrow to see real oil pressure.

Jeff20B

iTrader: (13)

Ok I've got a happy update. The mechanical oil pressure gauge says the ROPR smash job I did resulted in 80psi. That matches the 8k redline perfectly. (remember we've got 3mm apex seals, and the bridges kick in at 4k so this engine doesn't need to scream to high RPM to throw you back in the seat). Then with fully warmed up oil (190F-200F) at below 1k we have 10psi. That's a little lower than I would have liked to see, but on the upside, I've had two other R5 engines that read the same ie 10psi at a really low idle, or 15psi above 1k. This half BP tends to idle best with a little brap at 1100, oil pressure is around 15psi. Then you rev it and the oil needle jumps up quick, basically matching RPM almost to a T.

So anyway this is the third R5 engine I've built and its idle oil pressure is the same as the other two, then it shoots up to where ever the ROPR was set to as soon as you rev it, just like the other two. I think it might be inherent to these R5s? The bearings were in great shape. The oil pump was a 17.5mm. The front pressure reg was left alone but it doesn't cause any low oil pressure issues. Just about the only possibility could be the front cover o-ring I suppose, like maybe it got pinched, but I checked it right before the front cover went on, and I've never pinched one before.

Anyway the engine is basically complete. So far I've given it three heat cycles. Every time it starts up a little easier. I also changed spark plugs to a set of BR8EQ-14s because I discovered the 2nd gen plugs don't run as well when you've got a stock FB ignition system. I tested 16 plugs today. BR8EQ-14s ran the best.

LizardFC

iTrader: (1)

When I scrolled down the page, I saw that temp gauge and thought it was a compression gauge. Was like, "Whaaaa?"

Good job, and keep up the updates. They're continued motivation for my own upcoming build.

j9fd3s

iTrader: (3)

with the rotary, the intake sits right above the exhaust, so i think it gets enough heat that the coolant doesn't make a huge difference

Jeff20B

iTrader: (13)

The coolant actually helps keep the manifold cool under certain conditions. That's why I like to block the ACV port, so the coolant has less heat to take away. But then I also block the coolant ports. As a rule, always block the ACV port first. Then it's option to block the coolant ports. Never the other way around.

Ok I've got a great update. It turns out my oil pressure is right in line with stock specs after all. Idle is right at 14 psi. When I rev it to 3k, it sits at 71psi. These are both in the stock range. Oil temp fully warmed up (measured in the pan with the temp gauge seen above) is 190°F.

It's now idling like a very healthy half bridgeport. It's like those videos you see on youtube of half BP T2s and FDs. A little brap that sometimes pushes/rocks the the car to one side. It's really cool. This was the forth and final heat cycle. It passed this test perfectly and is now ready to pull. Colten is going to really like this engine I think.

Sorry LizardFC, I'm basically done with this engine. The next half BP I'm doing will be on an FD/T2 hybrid but it will be a littlw while until I can get to it. But I'll still be here to answer questions as best I can. My next engine will be a 74 spec 4 port "automobiles" older style R5 13B for the white REPU. I'll pay close attention to the oil pressure since I've done three modern R5s with seemingly low oil pressure without a known cause, so good to get another opinion.

Hey Mike, this half BP changes its brap depending on whether the clutch is push in or out. It seems spinning the tranny adds just a slight load. Did you experience the same thing with peepers?

j9fd3s

iTrader: (3)

not that ive really noticed? it does sometimes stall when you put the clutch in coming to a stop though, so maybe it does....

it will kind of go in and out of normal to brap idle just sitting there though. so if you reach in the window and start it (you can do that!) it'll brap for a bit and then when its warm kind of go back and forth

hmm actually, so the P port just starts with the timing @18BTDC, but the haltechs actually kick back if you have the timing much over 5BTDC cranking, i wonder why?

Jeff20B

iTrader: (13)

Yeah this will sometimes stall like that too. I just figured it's a fresh rebuild and will do that for a while.

I haven't gotten warm starts figured out yet. I know the hot start assist opens the carb a little so I've been doing that. Still takes a couple seconds.

I have no idea about haltechs. I have timing set to 0 with the dizzy static timed. This pulley is correct for the hub. They're a matched set from the factory an dcame stock with a 15 degree split (it's an R5 thing). I marked it for a 10 degree split.

JoeNoble

iTrader: (6)

Ok I've got a bit of a newb question. When you say "R5" what is that referring to?

rxtasy3

iTrader: (2)

i believe it's stamped on the center housing. that's something i've been meaning to check on mine since reading bout it a while back but it's hard to see/make out with it sitting in the car. i do know that mine has the tall port center housing.

j9fd3s

iTrader: (3)

with the P port the intake flange is like 1/8" away from the header flange, so intake temp changes a LOT, i did wrap the intake right at the motor and this helped, but it still kind of does it. after a little drive, the intake will be cold to the touch by the carb, but hot to the touch by the engine.

and the weber doesn't have an air temp compensation map.

so for me its a tuning thing, it feels like the idle is a little lean too