peejay

Jeff your problems with EFI were probably very very basic. The fuel pump has nothing to do with how much pressure there is. I have had Walbro 255s at 43psi, at 15psi in a TBI installation, whichever. If i ever go to an intank pump, I'll probably use a pair of 255s.

If there are simple yet fundamental problems, you will never get anything figured out. This goes for carbs too...

Jeff20B

iTrader: (13)

All I can say to that is when I had a walbro 255 in the brown car with a mallory 4309 fpr, the lowest the pressure would go was about 5.5 psi. Then I swapped to an MSD 2225 pump. The resulting fuel pressure went down to 2.4 to 3.0 psi which was just low enough for a Nikki. Then I redid my fuel lines to what mallory recommends in their instructions: 5/16" send and 3/8" return, and the resulting fuel pressure was further reduced to 1.5 psi which allowed me to adjust it up a little to 2.5 psi with the set screw and virtually eliminated some flooding problems I was having.

I have another example. Karack constantly recommends against walbro 255 pumps in FCs due to their base pressure which, he says, is at 60 psi and they lead to flooding stock NA FCs. I don't know all the detail and I assume the problems arise from using stock FPRs on the stock rails, but he has a lot more EFI experience than I do, so I defer to him on this.

And lastly, the 20B had the walbro 255 and a stock rail with a stock FPR. And it would flood every time I'd go to start it. Something tells me it shouldn't have been that difficult. Was the walbro 255's base pressure of supposedly 60 psi to blame? Was my priming pulse to blame? I later turned it off and it still flooded almost every time, so maybe partially. Would a different fuel pump have been a better choice? Maybe a different fpr? I honestly don't know. You have more EFI experience than I do. What are your thoughts? JC Cosmo parts are very similar to S5 FC parts so think of it like an S5.

j9fd3s

iTrader: (3)

ive done all kinds of ecu's, but the megasquirt is intimidating, because it doesn't have a cogent instruction manual. and the hardware varies.

also standalones are tough just because rewiring half the car is really invasive, and there are just a lot of things that can and do go wrong.

Jeff20B

iTrader: (13)

Speaking of invasive, I honestly couldn't tell because I was so new to EFI and the first two MS installs were in cars that had sat a long time which let me take my time on them. I also happen to like wiring so the harnesses weren't intimidating. I just couldn't wrap my head around the latter stages of setting up the software and tuning. I know for most people, their experience is like a perfect 180 degrees from mine, where the tuning is the part they look forward to the most and dread the initial wiring/setup etc. So I guess I'm backwards. lol

I also can't help but notice in the video I posted of my half BP 12A, the engine just has a nice mild brap at idle while peejay's sounds angry. Or angrier than mine at least. Mine just had a pretty much stock old school Nikki on a stock sep runner manifold. The bridge ported secondaries were completely closed off with zero communication between each other or the primaries. And it worked great!

Fast forward to now. I was hoping the knife edged channel the PO did to my recently acquired RX-2 manifold would be an improvement, but both j9fd3s and peejay recommend against it. Thus I decided to go with the completely sep runner RX-3 manifold instead. The size and shape of the 3 mani might let an S5 turbo fit next to it, once I trim the ACV section of the casting down. Obviously the ACV port in the intermediate plate will get blocked by quicksteel.

So yes maybe I'm just not mentally cut out for EFI? Things that most would find child's play just didn't make sense to me, so I might have gone the wrong direction and the end result was less than ideal. We all struggle at first but I know if you stick to it and try different things, it'll work out eventually. However since I really had little to no desire to bother with EFI in the first place, it didn't take much for me to say eff it! At the same time I felt compelled to figure out a hogged out + boost prepped Nikki, which after a year and eight months I've spent on them thus far, have worked out great.

Now I don't know if peejay genuinely likes his EFI experience better than any of his former carb experiences, whether Nikki or Holley, but I can venture to say that if a properly hogged out Nikki was available over ten years ago without all the Yaw and Sterling carb problems, I can't help but think he might have enjoyed it more than his mostly stock ones he experimented with on variously modded manifolds. It was peejay who brought to our attention that channels are actually necessary to get past the limited flow of the primary runners in all 81-85 manifolds, and I think he also mentioned how port matching to the tall intermediate Y plate runners is wrong. It might have been someone else. So in case I haven't said it before, Thank you peejay for figuring this stuff out so long ago.

It took me a long time to get into Nikkis because I was quagmired with the belief that Hitachi carbs were good and even superior to Nikkis in a lot of ways as they were calibrated to run properly on the old school 13Bs, which peejay likes to point out are just stretched 12As. And because all I had around here were REPUs and other old schools, I had zero reason to try any Nikki stuff. Even after I got an FB, it still took me years to even bother messing with Nikki. It took me until 2012 when I was testing setups on the freshly built Icy engine in the blue car to try the Racing Nikki for the first time. I already mentioned how Mr *******'s tune was extremely wrong and how swapping in stock SA air bleeds fixed the problem. I still have zero explanation for how they were able to drive that carb on the big streetported 12A it came off of because last time I checked a 13B is a bigger engine that requires more air at the same RPM, with some exceptions for porting size, I'm sure. The point is throwing away someone elses tune and going with my own, made the carb work. Its just like what j9fd3s had to do with the MFR tune sheet for peepers. That's where "give it what it wants" came from, and I thank him for that,. It helped me discover that no matter what the wideband says, give it what it wants. Turns out it wants 12.2 as the perfect idle tune so I aim for that on every carb I do.

Getting back to the half BP, all I want is a similar nice brap like the first engine had. However I wouldn't mind if it got a little angrier. I also have four intake manifolds to test on it. And who knows. Maybe the knife edged manifold will work better.

peejay

I had a much larger Bosch pump running on an FC engine and fuel pressure was stock.

Fuel pump NEVER alters pressure unless your regulator is so small that it is a restriction even at max opening. Fuel pumps do not create pressure, they create flow, the regulator's restriction creates pressure.

Honda D-series guys have to relieve their regulators. I have never seen it on an RX-7.\

There was also a supposed carb turbo expert here, who may have indeed made good turbo setups, but who also insisted that you reference the regulator to the manifold on a blowthrough setup instead of the carb hat. Which is incredibly wrong.

Jeff20B

iTrader: (13)

Well I can't argue further about fuel pumps because I already said all I know about them. What I can say is that I recommend the MSD 2225 pump along with a Mallory 4309 fpr if doing a boosted Nikki, because it worked perfectly for me. Oh and follow the directions they give you about fuel line diameter because it made a difference on my setup.

I know someone who fits that description and I can find the thread where he mentions it. His first name begins with the letter R. See post #22 https://www.rx7club.com/1st-generati...4/#post7809917

When I tried what he said on my Nikki setup; hooking the fpr to the manifold, it ran so lean I'm glad my boost was still so low in those days that it didn't blow up. I promptly returned it to the carb hat and was a little wiser for the wear.

Also in my opinion, webers make terrible boosted carbs on rotaries. I know of three people right off the top of my head who tried it and found out how terrible it was and had to switch back to NA or to EFI. If they'd gone to a proper boost prepped Nikki, not necessarily one of Mr R's, but a correctly set up one, I'm sure it would have worked out for them. But that's another thread for another day.

peejay

In the back of my mind (way, way back) I want to try blowthrough Webers on something. Or Dell'Ortos. Because Lotus Esprit Turbos were blowthrough Dell'Ortos.

And remember: Just because someone did something doesn't mean it's a good idea to do it too!

j9fd3s

iTrader: (3)

i've seen some weird stuff happen, the most dangerous one was Higgi showing me a log of his 20B fuel pressure with the stock regulator. it tops out @10psi. so fuel pressure goes up with boost until 10psi, and then it doesn't!

i've heard of people's fuel pressure coming up with the walbro, but the stock T2 runs a two speed fuel pump, so it shouldn't be a problem?

j9fd3s

iTrader: (3)

lol, i dunno about a turbo weber setup, it seems like you'd want a carb with secondaries, like a nikki, just so you have an off boost circuit, and an on boost circuit. although i've never done a turbo carb setup

Jeff20B

iTrader: (13)

Of course my primaries do make boost. A lot of it. I was pleasantly surprised earlier this year when I started breaking them loose in 2nd gear on primaries only. I think I was trying to burn off some 87 octane so I knew I shouldn't floor it to get into boost, but it lit them up anyway lol.

You just lay into the pedal until you feel the hard spot at about 60% where the secondary linkage is, but you don't press any further and just hold the pedal there. The turbo spools up and it spins the tires. Not as dramatically or quickly as when the secondaries are open, but it still makes boost on primaries.

These Nikkis, I tell yah!

It's super easy to control, though. Don't misunderstand. You can drive like Old Grandpa or some punk teenager with this setup. It's certainly not an on/off switch like some setups. It's actually quite pleasant and predictable, which is probably why I keep recommending it to others.

peejay

That reminds me of the time I bricked my pants... last night when I finally got around to installing a boost gauge in my Volvo. Convention seems to be to plumb it in to the fuel pressure regulator hose, so after mounting the gauge, shoving the line through the firewall, and wiring in the gauge light (Volvo made this EASY, they use big fat wiring bridges for a lot of things), I went under the hood and removed the plastic cover over the throttle body and fuel pressure regulator.

The hose was blown off of the regulator, and fuel was everywhere. Cycle the key, and yep the regulator heaved fuel all over the place.

So after turning the boost up 9psi over stock, I had been driving around with way low fuel pressure. Not to mention spraying fuel everywhere, although fortunately it's nowhere near the exhaust. I'm a little worried to pull the plugs for a look, how well do 9.5:1 engines with Subaru-like short piston heights like to deal with 13 pounds of boost while running lean?

37 clicks (in a row) counterclockwise on the Turbosmart controller later, it was down to stock boost and I'm limping along until the new regulator shows up.

Insult to injury: New regulator is $300 from Volvo. Reg looks identical to the ones used on countless VWs and even many GM products, but GM are 4-bar, VW are 3.5-bar, and Volvo apparently are the only people in the world to use a clip in reg with 3-bar pressure. Dang.

j9fd3s

iTrader: (3)

lol, just run the 3.5, you'd never notice the difference

peejay

I already have the Volvo reg on order. I had been idly wondering my my fuel economy dropped to 20mpg and I just figured it was due to the douchebag who drives the car.

I blame him for a lot of things...

j9fd3s

iTrader: (3)

yeah that guy! which volvo is it?

peejay

I wish I could find the thread but can't. There was an annoying snob who posited that the only reason people bought small cars was because they couldn't afford big ones. (The username JoeR1 springs to mind) The example he used was that nobody bought an S40 because they wanted an S40, they bought it because they couldn't get an S80. I told him he was full of ****.

So, 10-13 years later, I have an S40 and my main gripe with it is that it is too large. And I have the small one, not the Ford-based one. And I'm looking at buying a Focus RS but only if the rumors of a Fiesta RS turn out to be false. New Focuses are GIANT cars.

j9fd3s

iTrader: (3)

lol, i agree. the Rx8 is ok out the front, but looking in the rearview is like there is just so much car back there (doing nothing, i might add).

that being said, i was in the truck behind FM's 1st gen all the way to sevenstock (the volvo goes to svenstock!), and the 1st gen looks really teeny..

but yeah, S40 > S80. the S80 is a turd.

i've been tempted to get an 850 wagon, but again, its too big.